U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

Ambulatory Surgery Data From Hospitals and 

Ambulatory Surgery Centers: United States, 2010

by Margaret J. Hall, Ph.D., Alexander Schwartzman, Jin Zhang, and Xiang Liu, Division of Health Care Statistics

Abstract

Objectives—This report presents national estimates of surgical and nonsurgical 

ambulatory procedures performed in hospitals and ambulatory surgery centers (ASCs) 

in the United States during 2010. Patient characteristics, including age, sex, expected 

payment source, duration of surgery, and discharge disposition are presented, as well 

as the number and types of procedures performed in these settings. 

Methods—Estimates in this report are based on ambulatory surgery data collected 

in the 2010 National Hospital Ambulatory Medical Care Survey (NHAMCS). 

NHAMCS has collected outpatient department and emergency department data since 

1992 and began gathering ambulatory surgery data from both hospitals and ASCs in 

2010. Sample data were weighted to produce annual national estimates.

Results—In 2010, 48.3 million surgical and nonsurgical procedures were 

performed during 28.6 million ambulatory surgery visits to hospitals and ASCs 

combined. For both males and females, 39% of procedures were performed on those 

aged 45–64. For females, about 24% of procedures were performed on those aged 

15–44 compared with 18% for males, whereas the percentage of procedures performed 

on those under 15 was lower for females than for males (4% compared with 9%). 

About 19% of procedures were performed on those aged 65–74, while about 14% 

were performed on those aged 75 and over. Private insurance was listed as the 

principal expected source of payment for 51% of ambulatory surgery visits, Medicare 

for 31% of visits, and Medicaid for 8% of visits. The most frequently performed 

procedures included endoscopy of large intestine (4.0 million), endoscopy of small 

intestine (2.2 million), extraction of lens (2.9 million), insertion of prosthetic lens 

(2.6 million), and injection of agent into spinal canal (2.9 million). Only 2% of visits 

with a discharge status were admitted to the hospital as an inpatient.

Keywords: outpatient surgery • procedures • ICD–9–CM • National Hospital 

Ambulatory Medical Care Survey (NHAMCS)

Introduction

This report presents nationally 

representative estimates of ambulatory 

surgery performed in hospitals and 

ambulatory surgery centers (ASCs) 

gathered by the 2010 National Hospital 

Ambulatory Medical Care Survey 

(NHAMCS). Ambulatory surgery, 

also called outpatient surgery, refers 

to surgical and nonsurgical procedures 

that are nonemergency, scheduled in 

advance, and generally do not result in an 

overnight hospital stay. 

Ambulatory surgery has increased in 

the United States since the early 1980s 

(1,2). Two factors that contributed to this 

increase were medical and technological 

advancements, including improvements 

in anesthesia and in analgesics for the 

relief of pain, and the development and 

expansion of minimally invasive and 

noninvasive procedures (such as laser 

surgery, laparoscopy, and endoscopy) 

(3–6). Before these advances, almost 

all surgery was performed in inpatient 

settings. Any outpatient surgery was 

likely to have been minor, performed 

in physicians’ offices, and paid for by 

Medicare and insurers as part of the 

physician’s office visit reimbursement. 

National Health Statistics Reports

Number 102  February 28, 2017
Page 2 National Health Statistics Reports  Number 102  February 28, 2017

The above advances and concerns 

about rising health care costs led to 

changes in the Medicare program in 

the early 1980s that encouraged growth 

in ambulatory surgery. Medicare 

expanded coverage to include surgery 

performed in ASCs (both hospitalbased and freestanding). In addition, a 

prospective payment system for hospitals 

based on diagnosis-related groups 

was adopted, and that created strong 

financial incentives for hospitals to shift 

some surgery out of the hospital (1–5). 

Ambulatory surgery proved to be popular 

among both physicians and patients 

(3,4,7,8), and the number of Medicarecertified ASCs increased steadily, from 

239 in 1983 to 5,316 in 2010 (9,10).

 This report covers ambulatory 

surgery performed in hospitals and 

ASCs that are independent of hospitals. 

Ambulatory surgery procedures 

performed in physicians’ offices and 

independent screening or diagnostic 

centers were not included in this report.

Methods

Data source and sampling 

design

Data for this analysis are from 

the ambulatory surgery component 

of the 2010 NHAMCS, a nationally 

representative survey of hospitals and 

ASCs conducted by the National Center 

for Health Statistics (NCHS). This 

survey has provided data on ambulatory 

medical care services provided in hospital 

emergency and outpatient departments 

since 1992. From 2010 through 2012, 

NHAMCS gathered data on ambulatory 

surgery procedures in both hospitals and 

ASCs. In 2013, data collection in ASCs 

was suspended so a new sampling frame 

could be developed. Previously, during 

1994–1996 and in 2006, the National 

Survey of Ambulatory Surgery (NSAS) 

gathered data from hospital-based ASCs 

(HBASCs) and from facilities independent 

of hospitals [then called freestanding 

ASCs (FSASCs)] (2). The terms HBASC 

and FSASC are no longer in use because 

Medicare, and other insurers following 

Medicare’s lead, changed the name and 

nature of the reimbursement categories 

for these services. Ambulatory surgery 

performed in hospitals is now called 

hospital outpatient department surgery. 

Facilities independent of hospitals that 

specialize in ambulatory surgery are now 

known as ASCs. 

Independent samples of hospitals 

and ASCs were drawn for the NHAMCS 

ambulatory surgery component. The 

NHAMCS hospital sample (11) was 

selected using a multistage probability 

design, first sampling geographic units 

and then hospitals. Locations within the 

hospital where the services of interest 

were provided, in this case ambulatory 

surgery, were sampled next. Lastly, 

patient visits within these locations were 

sampled. 

The hospitals that qualify for 

inclusion in this survey (the universe) 

include noninstitutional hospitals 

(excluding federal, military, and 

Department of Veterans Affairs hospitals) 

located in the 50 states and the District 

of Columbia. Only short-stay hospitals 

(hospitals with an average length of stay 

for all patients of fewer than 30 days), 

those with a general specialty (medical 

or surgical), and children’s general were 

included in the survey. These hospitals 

must also have six or more beds staffed 

for patient use. The 2010 NHAMCS 

hospital sample frame was constructed 

from the products of SDI Health’s 

“Healthcare Market Index,” which was 

updated July 15, 2006, and its “Hospital 

Market Profiling Solution, Second 

Quarter, 2006” (12). These products were 

formerly known as the SMG Hospital 

Market Database. 

In 2010, the sample consisted of 

488 hospitals, of which 74 were 

out-of-scope (ineligible) because they 

went out of business or otherwise failed 

to meet the criteria for the NHAMCS 

universe. Of the 414 in-scope (eligible) 

hospitals, 275 had eligible ambulatory 

surgery locations. Of these, 227 

participated, yielding an unweighted 

hospital ambulatory surgery response 

rate of 82.6% and a weighted response 

rate of 90.9%. All of the 321 ambulatory 

surgery locations within the 227 

participating hospitals were selected 

for sampling, and 281 of these fully or 

adequately responded [at least one-half 

of the number of expected patient record 

forms (PRFs) were completed]. The 

resulting hospital ambulatory surgery 

location sample response rate was 87.5% 

unweighted, and 86.9% weighted. The 

overall hospital response rate was 72.2% 

unweighted and 79.0% weighted. In all, 

18,469 PRFs for ambulatory surgery 

visits were submitted by hospitals.

 The ASCs that qualified for 

inclusion in the 2010 NHAMCS (the 

universe) only included facilities in the 

2006 NSAS sample. This sample was 

drawn in 2005 from a universe consisting 

of facilities listed in the 2005 Verispan 

(later called SDI Health and then IMS 

Health) Freestanding Outpatient Surgery 

Center Database (13) or the Centers for 

Medicare & Medicaid Services’ (CMS)

Medicare Provider of Services file (14). 

Using both of these sources resulted in 

a list of facilities that were regulated or 

licensed by the states and those certified 

by CMS for Medicare participation. 

More details about the 2006 NSAS 

sample have been published elsewhere 

(2). Selection of the 2010 ASC sample 

began with the NSAS 2006 stratified list 

sample of 472 FSASCs, which had strata 

defined by four geographic regions and 

17 facility specialty groups. Seventy-four 

facilities were out-of-scope, leaving 398 

facilities from which to select the 2010 

NHAMCS ASC sample. To the extent 

possible, the ASC sample was selected 

from the NHAMCS geographic sampling 

units. The 17 specialty group strata used 

in the 2006 NSAS sample were collapsed 

into 5 strata (ophthalmic, gastrointestinal, 

multispecialty, general, and other). 

All of the in-scope 2006 NSAS 

sample facilities located within the 

NHAMCS geographic sampling units 

were selected, yielding 216 facilities. 

To achieve the desired 246 facilities, a 

stratified list sample of 30 facilities was 

drawn from the remaining in-scope 2006 

NSAS sample facilities that were located 

outside of the NHAMCS geographic 

sampling units. Strata were defined by 

the four regions and the five collapsed 

surgery specialty groups. 

There were 149 in-scope (eligible) 

ASCs and, of this number, 109 responded 

to the survey for an unweighted response 

rate of 73.2% and a weighted response 

rate of 70.2%. In all, 8,492 PRFs were 

submitted for ASCs. 

The overall response rate for 

hospitals combined with ASCs was 

72.2% unweighted and 79.0% weighted. 
National Health Statistics Reports  Number 102  February 28, 2017 Page 3

The combined number of PRFs from both 

of these settings was 26,961.

Facilities were selected using a 

multistage probability design, with 

facilities having varying selection 

probabilities. Patient visits to ASCs 

and to locations in the hospital where 

ambulatory surgery was provided were 

selected using systematic random 

sampling procedures. 

Within each sampled hospital, a 

sample of ambulatory surgery visits 

was selected from all of the ambulatory 

surgery locations identified by hospital 

staff. These locations included main 

or general operating rooms; dedicated 

ambulatory surgery units; cardiac 

catheterization laboratories; and rooms 

for endoscopy, laparoscopy, laser 

procedures, and pain block. 

Locations within hospitals dedicated 

exclusively to abortion, dentistry, 

podiatry, family planning, birthing, 

or small procedures were excluded, 

but these procedures were included 

if performed at in-scope locations. In 

ASCs with in-scope specialties, all visits 

were sampled. Facilities specializing 

in abortion, dentistry, podiatry, family 

planning, birthing, or small procedures 

were excluded, but these procedures were 

included if performed at in-scope ASCs. 

To minimize response burden for 

hospitals and ASCs, the samples were 

divided into 16 nationally representative 

panels, and those panels were randomly 

ordered for rotation over reporting 

periods of 4 weeks each. Within the 

reporting periods, patient visits were 

systematically selected. The visit lists 

could be sign-in sheets or appointment 

lists. The total targeted number of 

ambulatory surgery visit forms to be 

completed in each hospital and in each 

ASC was 100. In facilities or hospitals 

with volumes higher than these desired 

figures, visits were sampled by a 

systematic procedure that selects every 

nth visit after a random start. Visit 

sampling rates were determined from 

the expected number of patients to be 

seen during the reporting period and the 

desired number of completed PRFs.

Data collection

Medical record abstraction was 

performed by facility staff or U.S. Census 

Bureau personnel acting on behalf of 

NCHS. A PRF for each sampled visit was 

completed. A visit is defined as a direct 

personal exchange between a physician 

or a staff member operating under a 

physician’s direction, for the purpose of 

seeking ambulatory surgery. Visits solely 

for administrative purposes and visits in 

which no medical care was provided are 

out-of-scope.

The PRF contains items relating 

to the personal characteristics of the 

patients, such as age, sex, race and 

ethnicity, and administrative items, 

such as the date of the procedure, 

expected source(s) of payment, 

and discharge disposition. Medical 

information collected includes provider 

of anesthesia and type of anesthesia, 

length of time in both the operating 

room and in surgery, symptoms present 

during or after the procedure, and up to 

five diagnoses and seven procedures, 

which were coded according to the 

International Classification of Diseases, 

Ninth Revision, Clinical Modification 

(ICD–9–CM) (15). Information on up to 

12 new or continuing prescription and 

over-the-counter drugs ordered, supplied, 

or administered during the visit or at 

discharge was also collected, and these 

drugs were coded using Multum Lexicon 

(16), a proprietary drug classification 

system used by NCHS. 

Limitations of NHAMCS 

Ambulatory Surgery 

Data

Limited resources did not permit 

updating the ASC frame for the 2010 

NHAMCS, so the NSAS 2006 sample, 

based on ASCs in existence in 2005, 

was used. Based on annual data on the 

number of Medicare-certified ASCs from 

CMS, the increase in the number of these 

facilities was taken into account in the 

calculation of NHAMCS ASC survey 

weights. The visit total related to the 

increase in the number of ASCs was also 

accounted for in the weights, but any 

possible change in the number of visits 

per ASC was not accounted for because 

no data were available on the number of 

visits to ASCs over time. Final weighting 

is described in more detail elsewhere (11).

Based on the assumption that the 

characteristics of ambulatory surgery 

visits probably do not vary with facility 

age, the sample should enable the 

measurement of 2010 characteristics (if 

not numbers) of ambulatory visits. To the 

extent that the ASCs that existed in 2005 

were different from those in existence 

in 2010, these differences would not 

have been fully captured by the 2010 

NHAMCS (17). 

Due to limited resources, the 

sample sizes for hospitals and for ASCs 

for the NHAMCS ambulatory surgery 

component were only about one-half of 

what they were for the 2006 NSAS, so 

the most recent estimates have larger 

standard errors. This makes it more 

difficult for differences to achieve 

statistical significance. 

Until 2008, hospital ambulatory 

surgery was included under Medicare’s 

HBASC payment category. Beginning in 

2008, Medicare discontinued its use of 

this category and instead began paying 

for hospital ambulatory surgery as part of 

hospital outpatient department services. 

Hospitals also dropped the HBASC 

designation and, in some hospitals, 

this change led to a greater dispersion 

of ambulatory surgery procedures 

throughout the hospitals, including 

to various parts of the outpatient 

departments and locations within medical 

clinics.

Some hospitals had difficulty 

identifying all of the locations in the 

hospital where in-scope procedures were 

performed, especially in the first year 

of NHAMCS ambulatory surgery data 

collection (2009). This same year, after 

the problems became apparent, U.S. 

Census Bureau and NCHS staff provided 

additional information to field staff about 

how to identify locations in the hospital 

that were in-scope and out-of-scope 

for the ambulatory surgery component 

of NHAMCS. More formal training 

material on this point was provided in 

a 2010 training CD that was sent to all 

field staff. These efforts are believed to 

have corrected this problem. However, 

due to these issues, it is likely that some 

in-scope procedures were undercounted 

in 2009 and 2010. 

A number of changes occurred in 

the health care system during 2008–2010 

that could have affected the amount 
Page 4 National Health Statistics Reports  Number 102  February 28, 2017

of ambulatory surgery care that was 

provided in settings covered by this 

report and the amount provided in 

out-of-scope settings (e.g., physicians’ 

offices). More information about the 

difficulties of gathering and comparing 

data on ambulatory surgery from these 

two time periods and surveys is 

available (18). 

Results

Ambulatory surgery 

procedure and visit overview

● In 2010, 28.6 million ambulatory 

surgery visits to hospitals and ASCs 

occurred (Table 1). During these 

visits, an estimated 48.3 million 

surgical and nonsurgical procedures 

were performed (Table 2).

● An estimated 25.7 million (53%) 

ambulatory surgery procedures were 

performed in hospitals and 22.5 

million (47%) were performed in 

ASCs (Table A).

● Private insurance was the expected 

payment source for 51% of the visits 

for ambulatory surgery, Medicare 

payment was expected for 31%, and 

Medicaid for 8%. Only 4% were 

self-pay (Figure 1).

● Ninety-five percent of the visits with 

a specified discharge disposition 

had a routine discharge, generally 

to the patient’s home. Patients were 

admitted to the hospital as inpatients 

during only 2% of these visits 

(Table B). 

Ambulatory surgery 

procedures, by sex and age

● For both males and females, 39% of 

procedures were performed on those 

aged 45–64 (Figure 2). 

● For females, about 24% of 

procedures were performed on those 

aged 15–44 compared with 18% for 

males, whereas the percentage of 

procedures performed on those under 

15 was lower for females than for 

males (4% compared with 9%).

● About 19% of procedures were 

performed on those aged 65–74, with 

about 14% performed on those aged 

75 and over.

Table A. Ambulatory surgery procedures and visits to hospitals and ambulatory surgery 

centers: United States, 2010

Ambulatory surgery utilization Estimate Standard error

Procedures (millions) . . . . . . . . . . . . . . . . . . . . . . . . . . 48.3 4.3

 in hospitals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.7 2.6

 in ASCs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.5 3.3

Visits (millions) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28.6 2.4

 in hospitals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.7 1.6

 in ASCs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.9 1.8

NOTE: ASC is ambulatory surgery center.

SOURCE: NCHS, National Hospital Ambulatory Medical Care Survey, 2010.

Figure 1. Percent distribution of ambulatory surgery visits in hospitals and ambulatory 

surgery centers, by principal expected source of payment: United States, 2010

Table B. Percent distribution of ambulatory surgery visits in hospitals and ambulatory 

surgery centers, by discharge disposition: United States, 2010 

Discharge disposition Percent of visits

Routine discharge1

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Observation status2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Admission to hospital as inpatient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Other3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Total4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

1

Discharge to customary residence, generally home.

2

Discharge for further observation without being admitted to a hospital.

3

Includes discharge to postsurgical or recovery care facility, referral to emergency department, surgery terminated, and other 

options.

4

Excludes 1.2 million of the 28.6 million total visits with an unknown discharge disposition.

SOURCE: NCHS, National Hospital Ambulatory Medical Care Survey, 2010. NOTE: CHIP is Children’s Health Insurance Program and SCHIP is State Children’s Health Insurance Program.

SOURCE: NCHS, National Hospital Ambulatory Medical Care Survey, 2010.

 
National Health Statistics Reports  Number 102  February 28, 2017 Page 5

Types of procedures

Seventy percent of the 48.3 million 

ambulatory surgery procedures were 

included in the following clinical 

categories: operations on the digestive 

system (10 million or 21%), operations on 

the eye (7.9 million or 16%), operations 

on the musculoskeletal system 

(7.1 million or 15%), operations on 

the integumentary system (4.3 million 

or 9%), and operations on the nervous 

system (4.2 million or 9%) (Table 3). 

These procedure categories made up 72% 

of procedures performed on females and 

67% of those performed on males. Within 

the above-mentioned categories, data 

on procedures performed more than 1 

million times are presented below.

Under operations on the digestive 

system, endoscopy of large intestine—

which included colonoscopies—was 

performed 4.0 million times, and 

endoscopy of small intestine was 

performed 2.2 million times. Endoscopic 

polypectomy of large intestine was 

performed an estimated 1.1 million times.

Eye operations included extraction 

of lens, performed 2.9 million times; 

insertion of lens, performed 2.6 million 

times for cataracts; and operations on 

eyelids, performed 1.0 million times. 

Musculoskeletal procedures included 

operations on muscle, tendon, fascia, and 

bursa (1.3 million). 

Operations on the integumentary 

system included excision or destruction 

of lesion or tissue of skin and 

subcutaneous tissue (1.2 million).

Operations on the nervous system 

included injection of agent into spinal 

canal (2.9 million), including injections 

for pain relief. 

Duration of surgery

The average time in the operating 

room for ambulatory surgery was almost 

1 hour (57 minutes). On average, about 

one-half of this time (33 minutes) was 

spent in surgery. Postoperative care 

averaged 70 minutes. Time spent in the 

operating room, surgery, and receiving 

postoperative care were all significantly 

longer for ambulatory surgery performed 

in hospitals compared with ASCs 

(Table C).

The average surgical times for 

selected ambulatory surgery procedures 

are shown in Table D. Endoscopies 

averaged 14 minutes, while endoscopic 

polypectomy of the large intestine 

averaged 21 minutes. For cataract 

surgery, extraction or insertion of lens 

(often done together) averaged 10 

minutes, and operations on the eyelids 

averaged 23 minutes. Arthroscopy of the 

knee averaged 32 minutes.

Discussion

Keeping in mind the limitations 

that should be taken into account when 

comparing 2006 NSAS data and 2010 

NHAMCS ambulatory surgery data, 

the 53.3 million ambulatory surgery 

procedures estimated using 2006 NSAS 

data were compared with the 48.3 

million ambulatory surgery procedures 

estimated using 2010 NHAMCS data. 

The difference between these two 

figures was not statistically significant. 

A significant decrease of 18% (from 

34.7 to 28.6 million) was seen in the 

number of ambulatory surgery visits 

during this same time period. It had been 

expected based upon the limited data 

that were available and on projections 

from past trends, that there would have 

been an increase in the numbers of both 

ambulatory surgery visits and procedures 

(9,10,19). 

One reason for these findings could 

be an undercount in NHAMCS in 2010. 

Another reason that ambulatory surgery 

visit estimates could have decreased and 

ambulatory surgery procedures remained 

steady, could be the deep economic 

recession that began in 2007. By 2010, 

when NHAMCS began gathering 

ambulatory surgery data in both hospitals 

and ASCs, the economy had not fully 

recovered. The rate of unemployment 

and the number of people who did not 

have health insurance were higher in 

2010 compared with 2006, and both of 

these factors could have affected patients’ 

use of ambulatory surgery (20,21). Even 

for those who continued to have health 

insurance, increased out-of-pocket costs 

(higher deductibles and coinsurance 

payments) may have contributed to 

a decrease in the number of visits for 

ambulatory surgery (22).

An examination of various data 

sources, including Medicare, the American 

Hospital Association, and NHAMCS, was 

undertaken to evaluate if other national 

 1

Differences between females and males in these age groups are statistically significant. 

NOTES: Numbers may not add to totals because of rounding. See Table 2 in this report (NHSR 102, “Ambulatory Surgery 

Data From Hospitals and Ambulatory Surgery Centers: United States, 2010”) for standard errors.

SOURCE: NCHS, National Hospital Ambulatory Medical Care Survey, 2010.

 

Figure 2. Percent distribution of ambulatory surgery procedures in hospitals and 

ambulatory surgery centers, by age and sex: United States, 2010
Page 6 National Health Statistics Reports  Number 102  February 28, 2017

data sources reached similar conclusions 

about trends in ambulatory surgery during 

2006–2010 (19). This analysis revealed 

that the only nationally representative 

data during this time period were from 

the 2006 NSAS and the 2010 NHAMCS 

ambulatory surgery component. Medicare 

data on the number of certified ASCs 

over time existed, but only limited 

Medicare ambulatory surgery utilization 

and expenditure data were available, and 

almost all of it was from ASCs only and 

did not include data on ambulatory surgery 

in hospitals. Even so, Medicare utilization 

and expenditure data could not have been 

used to generalize to the entire population 

because Medicare only covers those aged 

65 and over and people with disabilities. 

Close to 70% of ambulatory surgery 

procedures were paid for by sources other 

than Medicare. 

Ambulatory Surgery 

Data

The 2010 NHAMCS ambulatory 

surgery data used for this report have 

been released in a public-use file 

available from: ftp://ftp.cdc.gov/pub/

Health_Statistics/NCHS/Datasets/

NHAMCS. The data base documentation 

for this file is available from: ftp://ftp.

cdc.gov/pub/Health_Statistics/NCHS/

Dataset_Documentation/NHAMCS.

Among the options being explored 

for future data collection are the use of 

both claims data and electronic health 

record data. 

References

1. Leader S, Moon M. Medicare trends 

in ambulatory surgery. Health Aff 

(Millwood) 8(1):158–70. 1989.

2. Cullen KA, Hall MJ, Golosinskiy A. 

Ambulatory surgery in the United 

States, 2006. National health statistics 

reports; no 11. Hyattsville, MD: 

National Center for Health Statistics. 

2009.

3. Davis JE. Ambulatory surgery...how 

far can we go? Med Clin North Am 

77(2): 365–75. 1993.

4. Lumsdon K, Anderson HJ, Burke M. 

New surgical technologies reshape 

hospital strategies. Hospitals 66(9):30–

6. 1992.

5. Duffy SQ, Farley DE. Patterns of 

decline among inpatient procedures. 

Public Health Rep 110(6):674–81. 

1995. 

6. MEDPAC. Report to the Congress: 

Medicare payment policy. Section 

F: Assessing payment adequacy and 

updating payments for ambulatory 

surgical center services. Washington, 

DC. 2003.

7. Durant GD. ASCs: Surviving, thriving 

into the 1990s. Med Group Manage J 

36(2):14. 1989.

8. KNG Health Consulting, LLC. 

An analysis of recent growth of

ambulatory surgical centers: Final

report. Prepared for the ASC Coalition. 

2009.

9. MEDPAC. Report to the Congress: 

Medicare payment policy. Chapter 5: 

Ambulatory surgical center services. 

Washington, DC. 2013.

10. MEDPAC. Report to the Congress: 

Medicare payment policy. Washington, 

DC. 2012.

11. National Center for Health Statistics. 

2010 NHAMCS public-use micro-data

file documentation. Available from: 

ftp://ftp.cdc.gov/pub/Health_Statistics/

NCHS/Dataset_Documentation/

NHAMCS.

12. Verispan LLC. Healthcare market 

index, updated July 15, 2006. 

Hospital market profiling solution, 

second quarter. Chicago: Healthcare 

Information Specialists. 2006.

13. Verispan LLC. Freestanding outpatient 

surgery centers database. Chicago: 

Healthcare Information Specialists. 

2005. 

14. Centers for Medicare & Medicaid 

Services. Provider of services file. 

Baltimore, MD. 2005.

Table D. Average surgical duration for selected procedures: United States, 2010

Selected procedure1 ICD–9–CM codes

Average 

surgical time 

(minutes)2

Standard 

error 

Endoscopy (including colonoscopy) . . . . . . . . . . 45.11–45.14, 45.16, 45.21–45.25 14 0.87

Endoscopic polypectomy of large intestine . . . . . 45.42 21 0.97

Extraction or insertion of lens (cataracts) . . . . . . 13.1–13.7 10 1.20

Operations on eyelids . . . . . . . . . . . . . . . . . . . . . 08 23 3.56

Arthroscopy of knee . . . . . . . . . . . . . . . . . . . . . . . 80.26 32 2.69

1

Times were counted only for patients who had each of these selected procedures and no others during their ambulatory surgery 

visit.

2

Calculated by subtracting the time surgery began from the time surgery ended. Surgical time typically extends from when the 

first incision is made until the wound is closed.

NOTE: Procedure categories and code numbers are based on the International Classification of Diseases, Ninth Revision, Clinical 

Modification (ICD–9–CM).

SOURCE: NCHS, National Hospital Ambulatory Medical Care Survey, 2010.

Table C. Distribution of times for surgical visits, by ambulatory surgery facility type: United States, 2010

Hospital Ambulatory surgery center All facilities

Calculated time of ambulatory surgical visit

Average time 

(minutes)

Standard

error

Average time 

(minutes)

Standard

error

Average time 

(minutes)

Standard

error

Operating room1

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 1.9 50 3.7 57 2.2

Surgical2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 1.5 29 3.2 33 1.7

Postoperative care3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 2.9 51 3.8 70 2.6

1

Calculated by subtracting the time when the patient entered the operating room from the time the patient left the operating room.

2

Calculated by subtracting the time the surgery began from the time the surgery ended. Surgical time typically extends from when the first incision is made until the wound is closed.

3

Calculated by subtracting the time when the patient entered postoperative care from the time the patient left postoperative care.

SOURCE: NCHS, National Hospital Ambulatory Medical Care Survey, 2010.
National Health Statistics Reports

 Number 102 February 28, 2017 Page 7

15. Centers for Disease Control and 

Prevention, Centers for Medicare 

& Medicaid Services. International 

classification of diseases, ninth 

revision, clinical modification. 6th ed. 

DHHS Pub No. (PHS) 11–1260. 2011. 

Available from: https://www.cdc.gov/

nchs/icd/icd9cm.htm.

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Lexicon. Available from: http://www.

multum.com/lexicon.html.

17. Shimizu I. Sampling design for 

the 2010–2012 National Hospital 

Ambulatory Medical Care Survey. 

In: Proceedings from the 2011 JSM 

Annual Meeting. Alexandria, VA: 

American Statistical Association. 2012. 

18. Hall MJ. The challenges of gathering 

and interpreting national data on 

ambulatory surgery over time. 

Proceedings from the 2013 JSM 

Annual Meeting. Alexandria, VA: 

American Statistical Association. 2014.

19. Hall MJ. Comparison of national 

data on ambulatory surgery from 

CDC’s National Hospital Ambulatory 

Medical Care Survey, Medicare, the 

American Hospital Association and 

SDI. Proceedings from the 2014 JSM 

Annual Meeting. Alexandria, VA: 

American Statistical Association. 2015.

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Briefing: Trends in health insurance 

coverage in the U.S.: The impact 

of the economy. 2010. Available 

from: http://www.allhealth.org/

briefingmaterials/TrendsinHealth 

InsuranceTranscript12-6-2010-1923.

pdf.

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Commission on Medicaid and the 

Uninsured. The uninsured: A primer—

Key facts about health insurance on the 

eve of health reform. 2013. Available 

from: https://kaiserfamilyfoundation.

files.wordpress.com/2013/10/7451-

09-the-uninsured-a-primer-key-factsabout-health-insurance.pdf. 

22. Manchikanti L, Parr AT, Singh V, 

Fellows B. Ambulatory surgery centers 

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at long-term survival. Pain Physician 

14(2):E177–215. 2011.

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9.0.1) [computer software]. 2005.
Page 8 National Health Statistics Reports  Number 102  February 28, 2017

Table 1. Number and percent distribution of ambulatory surgery visits, by age and sex: United States, 2010

Both sexes Female Male

Age group (years) Estimate Standard error Estimate Standard error Estimate Standard error

 Number (thousands)

Total. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28,588 2424 16,481 1,365 12,108 1,084

Under 15 . . . . . . . . . . . . . . . . . . . . . . . . . . 1,812 302 712 122 1,100 184

15–44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6,426 619 4,201 411 2,225 223

45–64. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10,911 1,010 6,256 555 4,659 474

65–74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,301 446 2,951 242 2,350 213

75 and over . . . . . . . . . . . . . . . . . . . . . . . . 4,139 360 2,365 205 1,774 167

Percent distribution

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 ... 100 ... 100 ... 

Under 15 . . . . . . . . . . . . . . . . . . . . . . . . . . 6 0.86 4 0.62 9 1.21

15–44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 0.94 26 1.06 18 0.91

45–64. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 0.89 38 0.84 39 1.16

65–74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 0.67 18 0.69 19 0.84

75 and over . . . . . . . . . . . . . . . . . . . . . . . . 14 0.69 14 0.72 15 0.83

... Category not applicable.

NOTE: Numbers may not add to totals because of rounding.

SOURCE: NCHS, National Hospital Ambulatory Medical Care Survey, 2010.
National Health Statistics Reports  Number 102  February 28, 2017 Page 9

Table 2. Number and percent distribution of ambulatory surgery procedures, by age and sex: United States, 2010

Both sexes Female Male

Age group (years) Estimate Standard error Estimate Standard error Estimate Standard error

Number (thousands)

Total. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48,263 4,253 27,595 2,373 20,669 1,932 

Under 15 . . . . . . . . . . . . . . . . . . . . . . . . . . 2,916 500 1,118 199 1,798 310 

15–44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10,478 1,014 6,708 631 3,770 418 

45–64. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18,783 1,876 10,789 1,060 7,994 857 

65–74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9,153 802 5,053 423 4,100 403 

75 and over . . . . . . . . . . . . . . . . . . . . . . . . 6,933 619 3,926 356 3,007 285 

Percent distribution

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 ... 100 ... 100 ... 

Under 15 . . . . . . . . . . . . . . . . . . . . . . . . . . 6 0.82 4 0.57 9 1.20

15–44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 0.89 24 0.92 18 1.10

45–64. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 1.02 39 1.05 39 1.23

65–74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 0.79 18 0.78 20 1.00

75 and over . . . . . . . . . . . . . . . . . . . . . . . . 14 0.80 14 0.84 15 0.89

... Category not applicable. 

NOTE: Numbers may not add to totals because of rounding.

SOURCE: NCHS, National Hospital Ambulatory Medical Care Survey, 2010.
Table 3. Number of ambulatory surgery procedures in hospitals and ambulatory surgery centers, by procedure category, sex, and age: United States, 201

Sex Ag

Procedure category and ICD–9–CM code Total Female Male Under 15 15–44 

Number (thousands) All procedures � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 48,263 27,595 20,669 2,916 10,478 

Operations on the nervous system � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(01–05,17.61) 4,226 2,385 1,841 * 1,002 

Injection of agent into spinal canal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .(03.91–03.92) 2,918 1,588 1,330 * 712 

Release of carpal tunnel � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (04.43) 444 266 178 – 66 

Operations on the eye � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (08–16) 7,880 4,622 3,258 93 321 

Operations on eyelids � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (08) 1,021 651 371 * * 

Extraction of lens � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(13.1–13.6) 2,861 1,705 1,156 * * 

Insertion of prosthetic lens (pseudophakos) � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(13.7) 2,553 1,526 1,027 * * 

Operations on the ear � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (18–20) 1,054 442 612 847 72 

Myringotomy with insertion of tube � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(20.01) 754 323 431 699 * 

Operations on the nose, mouth, and pharynx � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(21–29) 2,407 1,117 1,290 903 689 

Incision, excision and destruction of nose and lesion of nose � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (21.1,21.3–21.4,21.6) 302 152 * * 126 

Turbinectomy � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(21.6) 190 78 112 * 106 

Repair and plastic operations on the nose � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(21.8) 393 179 214 * 175 

Operations on nasal sinuses � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (22) 433 192 241 * 164 Tonsillectomy with or without adenoidectomy� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (28.2–28.3) 399 205 193 289 102 Adenoidectomy without tonsillectomy� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(28.6) 72 *32 *40 69 * 

Operations on the respiratory system � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(30–34) 282 141 141 * *40 

Bronchoscopy with or without biopsy � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (33.21–33.24,33.27,33.71–33.73,33.78–33.79) 106 *55 51 * * 

Operations on the cardiovascular system � � � � � � � � �(35–39,00.40–00.49,00.50–00.55,00.57,00.61–00.66,17.51–17.52,17.71) 1,072 519 553 * 88 

Cardiac catheterization � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(37.21–37.23) 339 136 203 * * 

Operations on the digestive system � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(42–54,17.1–17.3,17.63) 10,045 5,418 4,627 * 1,826 

Dilation of esophagus � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (42.92) 172 106 66 * * 

Endoscopy of small intestine with or without biopsy � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(45.11–45.14,45.16) 2,172 1,312 861 * 468 

Endoscopy of large intestine with or without biopsy � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (45.21–45.25) 3,987 2,202 1,785 * 474 

Endoscopic polypectomy of large intestine � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (45.42) 1,060 485 575 * * 

Laparoscopic cholecystectomy � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(51.23) 436 325 111 * 196 

Hernia repair � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(53.0–53.9,17.1–17.2) 777 196 581 * 178 

Repair of inguinal hernia � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(53.0–53.1,17.1–17.2) 449 *52 * * 82 

Operations on the urinary system � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(55–59) 1,349 590 759 *67 311 

Cystoscopy with or without biopsy � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(57.31–57.33) 479 219 260 * 128 

Operations on the male genital organs � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(60–64) 525 – 525 * 98 

Operations on the female genital organs � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(65–71) 1,766 1,766 – * 1,093 

Hysteroscopy � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(68.12) 198 198 – * 83 

Dilation and curettage of uterus � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(69.0) 328 328 – – 172 

See footnotes at end of table.
Table 3. Number of ambulatory surgery procedures in hospitals and ambulatory surgery centers, by procedure category, sex, and age: United States, 201

Sex Ag

Procedure category and ICD–9–CM code Total Female Male Under 15 15–44 

Number (thousands) Operations on the musculoskeletal system � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (76–84,00.70–00.77,00.80–00.87) 7,076 3,802 3,275 173 2,114 

Partial excision of bone � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(76.2–76.3,77.6–77.8) 241 132 109 * 49 

Reduction of fracture � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (76.7,79.0–79.3) 380 153 227 *52 160 

Injection of therapeutic substance into joint or ligament � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (76.96,81.92) 267 183 84 * * Removal of implanted devices from bone � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (76.97,78.6) 195 111 83 * 64 

Excision and repair of bunion and other toe deformities � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (77.5) 379 327 *52 * 120 Arthroscopy of knee � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (80.26) 692 332 359 * 254 

Excision of semilunar cartilage of knee � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(80.6) 759 374 385 * 196 

Replacement or other repair of knee � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (81.42–81.47,81.54–81.55,00.80–00.84) 571 285 286 * 201 

Operations on muscle, tendon, fascia and bursa � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(82–83) 1,274 636 637 * 319 

Operations on the integumentary system � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(85–86) 4,340 3,405 935 131 1,497 

Biopsy of breast � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (85.11–85.12) * * * – * 

Local excision of lesion of breast (lumpectomy) � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (85.21) 268 * * * 64 

Excision or destruction of lesion or tissue of skin and subcutaneous tissue � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (86.2–86.4) 1,219 734 485 * 323 

Miscellaneous diagnostic and therapeutic procedures and new technologies � � � � � � � � � � � � � � (87–99,00.01–00.03,00.09–00.19,00.21–00.25,00.28–00.29,00.31–00.35,00.39, 00.56, 00.58–00.59, 00.67–00.69,17.62,17.69,17.70,38.24,38.25,00.91–00.94,17.4) 5,892 3,102 2,790 228 1,225 

Operations on the endocrine system, on the hemic and lymphatic system, and obstetrical procedures � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(06–07,40–41,72–75) 348 285 63 * 104 

* Figure does not meet standards of reliability or precision. An asterisk with a number indicates that the estimate is based on a relatively small number of cases, and while reliable, should be used with caution. – Quantity zero. NOTE: Procedure categories and code numbers are based on the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD–9–CM). SOURCE: NCHS, National Hospital Ambulatory Medical Care Survey, 2010. 
Table 4. Standard errors of ambulatory surgery procedures in hospitals and ambulatory surgery centers, by procedure category, sex, and age: United Sta

Sex Ag

Procedure category and ICD–9–CM code Total Female Male Under 15 15–44 

Standard error All procedures � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 4,040 2,250 1,844 492 972 

Operations on the nervous system � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (01–05,17.61) 703 398 316 * 240 

Injection of agent into spinal canal � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (03.91–03.92) 557 305 265 * 208 

Release of carpal tunnel � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(04.43) 102 61 45 – 14 

Operations on the eye � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (08–16) 1,005 569 454 21 80 

Operations on eyelids � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(08) 203 130 100 * * 

Extraction of lens � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(13.1–13.6) 370 217 159 * * 

Insertion of prosthetic lens (pseudophakos) � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (13.7) 356 213 147 * * 

Operations on the ear � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (18–20) 188 107 94 184 12 

Myringotomy with insertion of tube � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (20.01) 161 91 83 152 * 

Operations on the nose, mouth, and pharynx � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (21–29) 312 155 173 194 88 

Incision, excision and destruction of nose and lesion of nose � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(21.1,21.3–21.4,21.6) 68 * 25 * 22 

Turbinectomy � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (21.6) 31 18 20 * 19 

Repair and plastic operations on the nose � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (21.8) 78 * 32 * 35 Operations on nasal sinuses � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(22) 92 48 59 * 35 

Tonsillectomy with or without adenoidectomy� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(28.2–28.3) 65 36 38 53 16 

Adenoidectomy without tonsillectomy� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (28.6) 15 *8 *10 14 * 

Operations on the respiratory system � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (30–34) 38 22 24 * *11 

Bronchoscopy with or without biopsy � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(33.21–33.24,33.27,33.71–33.73,33.78–33.79) 18 *12 11 * * 

Operations on the cardiovascular system � � � � � � � � �(35–39,00.40–00.49,00.50–00.55,00.57,00.61–00.66,17.51–17.52,17.71) 197 98 109 * 18 

Cardiac catheterization � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (37.21–37.23) 88 37 54 * * 

Operations on the digestive system � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (42–54,17.1–17.3,17.63) 1,148 608 555 * 196 

Dilation of esophagus � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(42.92) 32 23 14 * * 

Endoscopy of small intestine with or without biopsy � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (45.11–45.14,45.16) 290 171 128 * 69 

Endoscopy of large intestine with or without biopsy � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (45.21–45.25) 560 292 280 * 82 

Endoscopic polypectomy of large intestine � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(45.42) 195 93 108 * * 

Laparoscopic cholecystectomy � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (51.23) 64 48 20 * 27 Hernia repair � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(53.0–53.9,17.1–17.2) 113 31 89 * 30 

Repair of inguinal hernia � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(53.0–53.1,17.1–17.2) 72 * 61 * 19 

Operations on the urinary system � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (55–59) 184 79 114 *20 61 

Cystoscopy with or without biopsy � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (57.31–57.33) 75 38 44 * 31 

Operations on the male genital organs � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (60–64) 106 – 106 * 16 

Operations on the female genital organs � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (65–71) 223 223 – * 145 

Hysteroscopy � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(68.12) 33 33 – * 17 

Dilation and curettage of uterus � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (69.0) 42 42 – – 23 

See footnotes at end of table.
Table 4. Standard errors of ambulatory surgery procedures in hospitals and ambulatory surgery centers, by procedure category, sex, and age: United Sta

Sex Ag

Procedure category and ICD–9–CM code Total Female Male Under 15 15–44 

Standard error Operations on the musculoskeletal system � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (76–84,00.70–00.77,00.80–00.87) 1,156 667 501 36 305 

Partial excision of bone � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(76.2–76.3,77.6–77.8) 35 27 18 * 9 

Reduction of fracture � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(76.7,79.0–79.3) 50 19 36 *10 24 

Injection of therapeutic substance into joint or ligament � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (76.96,81.92) 58 43 20 * * 

Removal of implanted devices from bone � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(76.97,78.6) 37 27 15 * 16 

Excision and repair of bunion and other toe deformities � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (77.5) 72 69 *13 * 28 

Arthroscopy of knee � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(80.26) 168 80 91 * 47 

Excision of semilunar cartilage of knee � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (80.6) 177 79 103 * 39 

Replacement or other repair of knee � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(81.42–81.47,81.54–81.55,00.80–00.84) 141 80 66 * 36 

Operations on muscle, tendon, fascia and bursa � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (82–83) 201 113 96 * 62 

Operations on the integumentary system � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � (85–86) 496 423 111 32 217 

Biopsy of breast � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(85.11–85.12) * * * – * 

Local excision of lesion of breast (lumpectomy) � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(85.21) 39 39 * * 15 

Excision or destruction of lesion or tissue of skin and subcutaneous tissue � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(86.2–86.4) 129 103 56 * 58 

Miscellaneous diagnostic and therapeutic procedures and new technologies � � � � � � � � � � � � � � �(87–99,00.01–00.03,00.09–00.19,00.21–00.25, 00.28–00.29,00.31–00.35,00.39,00.56, 00.58–00.59, 00.67–00.69,17.62,17.69,17.70,38.24,38.25,00.91–00.94,17.4) 750 376 385 50 186 

Operations on the endocrine system, on the hemic and lymphatic system, and obstetrical procedures � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �(06–07,40–41,72–75) 50 45 14 * 21 

* Figure does not meet standards of reliability or precision. An asterisk with a number indicates that the estimate is based on a relatively small number of cases, and while reliable, should be used with caution. – Quantity zero. NOTE: Procedure categories and code numbers are based on the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD–9–CM). SOURCE: NCHS, National Hospital Ambulatory Medical Care Survey, 2010.
Page 14 National Health Statistics Reports  Number 102  February 28, 2017

Technical Notes

Data processing and medical coding 

were performed by SRA International, 

Inc., Durham, N.C. Editing and 

estimation were completed by the 

National Center for Health Statistics.

Estimation

Because of the complex multistage 

design of the National Hospital 

Ambulatory Medical Care Survey 

(NHAMCS), the survey data must 

be inflated or weighted to produce 

national estimates. The estimation 

procedure produces essentially unbiased 

national estimates and has three basic 

components: (a) inflation by reciprocals 

of the probabilities of sample selection, 

(b) adjustment for nonresponse, and (c) 

population weighting ratio adjustments. 

These three components of the final 

weight are described in more detail 

elsewhere (11).

Because NHAMCS ambulatory 

surgery data are collected from a sample 

of visits, persons with multiple visits 

during the year may be sampled more 

than once. Therefore, estimates are of 

the number of visits to, or procedures 

performed in, hospital ambulatory 

surgery locations and ASCs, and not 

the number of persons served by these 

facilities.

Standard errors

The standard error is primarily 

a measure of sampling variability 

that occurs by chance because only a 

sample, rather than the entire universe, 

is surveyed. Estimates of the sampling 

variability for this report were calculated 

using Taylor approximations in 

SUDAAN, which take into account the 

complex sample design of NHAMCS. 

A description of the software and the 

approach it uses has been published 

elsewhere (23). The standard errors of 

estimates presented in the tables of this 

report are included, either as part of 

the table or, in the case of Table 3, in a 

separate table (Table 4).

Data analyses were performed using 

the statistical packages SAS, version 9.3 

(SAS Institute, Cary, N.C.) and SAScallable SUDAAN, version 10.0 

(RTI International, Research Triangle 

Park, N.C.). 

Testing of significance and 

rounding

Differences in the estimates were 

evaluated using a two-tailed t test 

(p < 0.05). Terms such as “higher than” 

and “less than” indicate that differences 

are statistically significant. Terms such 

as “similar” or “no difference” indicate 

that no statistically significant difference 

exists between the estimates being 

compared. A lack of comment on the 

difference between any two estimates 

does not mean that the difference was 

tested and found not to be significant. 

Estimates of counts in the tables 

have been rounded to the nearest 

thousand. Therefore, estimates within 

tables do not always add to the totals. 

Rates and percentages were calculated 

from unrounded figures and may not 

precisely agree with rates and percentages 

calculated from rounded data.

Nonsampling errors

As in any survey, results are subject 

to both sampling and nonsampling errors. 

Nonsampling errors include reporting and 

processing errors as well as biases due to 

nonresponse and incomplete response. 

The magnitude of the nonsampling errors 

cannot be computed. However, efforts 

were made to keep these errors to a 

minimum by building procedures into 

the operation of the survey. To eliminate 

ambiguities and encourage uniform 

reporting, attention was given to the 

phrasing of items, terms, and definitions. 

Quality control procedures and 

consistency and edit checks reduced 

errors in data coding and processing. 

A 5% quality control sample of survey 

records was independently keyed and 

coded. Item nonresponse rates were 

generally low, but levels of nonresponse 

did vary among different variables. The 

data shown in this report are based upon 

items with low nonresponse.

Use of tables

The estimates presented in this report 

are based on a sample, and therefore 

may differ from the number that would 

be obtained if a complete census had 

been taken. The estimates shown in this 

report include surgical procedures, such 

as tonsillectomy; diagnostic procedures, 

such as ultrasound; and other therapeutic 

procedures, such as injection or infusion 

of cancer chemotherapeutic substance. 

In 2010, up to seven procedures 

were coded for each visit. All listed 

procedures include all occurrences of the 

procedure coded regardless of the order 

on the medical record. 

The procedure data in this report are 

presented by chapter of the International 

Classification of Diseases, Ninth 

Revision, Clinical Modification

(ICD–9–CM). In the Results section, 

selected chapters with large numbers 

of procedures are discussed along 

with specific categories of procedures 

performed 1 million or more times. The 

latter categories are included to give 

some examples of what was included 

under the chapters.

Table 3 presents data using 

ICD–9–CM codes for chapters 

of procedures as well as selected 

procedures within these chapters. The 

procedures selected for inclusion in 

Table 3 were those with relatively large 

frequencies, or because there was a 

clinical, epidemiological, or health 

services interest in them. 

Data from the 2010 NHAMCS 

showed that an estimated 479,000 

ambulatory surgery visits ended with an 

admission to the hospital as an inpatient. 

The visits made by these patients were 

included in this report [as they were in 

the 2006 National Survey of Ambulatory 

Surgery (NSAS) Report] (2), and the 

ambulatory surgery procedures they 

received were included in the estimates 

for all listed procedures. 

Estimates were not presented in 

this report if they were based on fewer 

than 30 cases in the sample data or if the 

relative standard error (RSE) was greater 

than 30%. In these cases, only an asterisk 

(*) appears in the tables. The RSE of 

an estimate is obtained by dividing the 

standard error by the estimate itself. The 

result is then expressed as a percentage 

of the estimate. Estimates based on 30 

to 59 cases include an asterisk because, 

while their RSE is less than 30%, these 

estimates are based on a relatively small 

number of cases and should be used with 

caution.
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Suggested citation

Hall MJ, Schwartzman A, Zhang J, Liu X. 

Ambulatory surgery data from hospitals and 

ambulatory surgery centers: United States, 

2010. National health statistics reports; no 102. 

Hyattsville, MD: National Center for Health 

Statistics. 2017.

Copyright information

All material appearing in this report is in 

the public domain and may be reproduced 

or copied without permission; citation as to 

source, however, is appreciated.

National Center for Health Statistics 

Charles J. Rothwell, M.S., M.B.A., Director

Jennifer H. Madans, Ph.D., Associate Director 

for Science 

Division of Health Care Statistics 

Denys T. Lau, Ph.D., Acting Director

Alexander Strashny, Ph.D., Associate Director 

for Science