Is Chlorhexidine Vaginal Preparation Prior to Hysterectomy Superior to Iodine in Reducing Bacterial Count; a Randomized Controlled Trial
Phase: PHASE4
Conditions: Hysterectomy
Sponsor: TriHealth Inc.

Chlorhexidine vs Iodine 1 
RESEARCH PROTOCOL 
 
Date 
7/20/20 
Title 
Is chlorhexidine vaginal preparation prior to hysterectomy superior 
to iodine in reducing bacterial count; a randomized controlled trial 
Principal Investigator 
Catrina  Crisp, MD MSc 
Sub-Investigators 
Rachel N. Pauls MD, Jennifer Yeung DO, Jack Basil MD, Tiffanie Tam, 
MD, Robert Neff, MD, Emily Aldrich, MD 
Research Specialist 
Eunsun Yook MS,  
Department 
Department of OB/Gyn, Division of Urogynecology and 
Reconstructive Pelvic Surgery, Division of Gynecology Oncology 
Hatton # 
17-102 
 
Purpose of Study   
• To determine the influence of chlorhexidine gluconate surgical/topical antiseptic 
solutions on the bacterial environment of the vagina during hysterectomy and 
compare that to the effect of standard iodine-based preparations on the same. 
o Primary Aim: To determine if chlorhexidine gluconate surgical preparation 
maintains a lower rate of contamination to the surgical field, as determined by 
bacterial count at 90 minutes from initial preparation, when compared to iodine 
based preparation. 
o Secondary Aims: To investigate the difference between chlorhexidine gluconate 
and iodine-based preparations influence on: 
 Rate of contamination at both 30 and 60 minutes from initial 
preparation.  
 Reducing specific pathogens commonly causing post-operative infection 
throughout the 90-minute window from preparation. 
 Reducing those pathogens that commonly cause bacterial vaginosis. 
 
Hypothesis or Research Question  
• We hypothesize that the percent of samples considered contaminated by bacterial 
count at 90 minutes from preparation will be 20% lower in the group that receives 
chlorhexidine preparation vs povidone-iodine.  

Chlorhexidine vs Iodine 2 
• We further hypothesize that this trend will be demonstrated throughout the 30-90 
minute time window following vaginal preparation.  
• Additionally, we hypothesize chlorhexidine will reduce bacterial counts of pathogens 
more commonly associated with post operative gynecologic infections better than 
povidone-iodine. 
• Finally, we hypothesize chlorhexidine will clear the pathogens associated with 
bacterial vaginosis more effectively than povidone-iodine.  
 
Background 
Although the rate of hysterectomy is declining nationally, it remains the most commonly 
performed procedure in gynecology1,2.  As such, postoperative infection remains the most 
common complication of surgical procedures in gynecology3.  Historically, 30-40% of patients 
undergoing a hysterectomy develop a post-operative infection4.  The initiation of antibiotic 
prophylaxis for appropriate surgical procedures was a significant advancement in the 
prevention of surgical site infection.  More than 30 prospective randomized clinical trials 
demonstrated reduced risk of infection and morbidity following hysterectomy when receiving 
antibiotic prophylaxis3. 
 
Overall incidence of post operative infection remains relatively low, with a recent cross 
sectional analysis of NSQIP (National Surgical Quality Improvement Program) data reporting 
2.7% occurrence for superficial, deep and organ space infections after hysterectomy5.  
Nonetheless, surgical site infections result in significant morbidity, loss of quality of life, higher 
risk of re-intervention, and increased costs to the patients affected by them9.  Within 
gynecology oncology, the risk of post operative infection remains as high as 36%10-13. Therefore, 
initiatives sponsored by the Centers for Disease Control, National Health Service Network, 
Centers for Medicare and Medicaid Services and the Joint Commission have targeted 
preventing and ultimately eliminating postoperative surgical site infections as a priority in 
patient safety efforts14.   
 

Chlorhexidine vs Iodine 3 
Antibiotic prophylaxis has been standardized3 and universally implemented.  A remaining 
variable is the method of aseptic preparation of the vagina with substantial variation of 
technique being reported even within institutions15.  This is concerning in light of the fact that 
most post-hysterectomy wound infections result from ascending spread of vaginal flora24,25. 
Removing variability and implementation of standardized protocols have shown infection rate 
reduction at large surgical centers9,12.  Establishing which aseptic solution should be 
implemented within these protocols remains challenging.  The most recent Committee Opinion 
by the American College of Obstetricians and Gynecologists concludes there is insufficient 
evidence to render a strong recommendation for either povidone-iodine or chlorhexidine as the 
ideal agent for surgical preparation of the vagina and that further evidence is necessary16.   
 
Povidone-iodine solution has been considered the standard for aseptic surgical preparation of 
the vagina for decades6-8 and is the only solution approved by the FDA for vaginal use16.  There 
are however specific qualities of the solution that suggest it may be less than ideal for use in 
the vagina. First, the vagina is not protected by keratinized epithelium and therefore iodine can 
be absorbed systemically during vaginal preparation17.  Second, iodine is less effective in low pH 
environments18. Considering the normal vaginal pH is 3.8-4.5, the aseptic properties of iodine 
are called into question as a vaginal solution. Finally, it has been shown that iodophores are 
inactived in the presence of blood18.  Therefore, by performing surgery and contaminating the 
prepared field with some quantity of blood, some degree of the desired asepsis is lost.  In light 
of these inadequacies, an alternative agent must be considered.  
 
More contemporary efforts have begun to focus on chlorhexidine as a more ideal agent for 
aseptic efforts in surgical preparation of the vagina.  In 2010, a large, multicentered, 
randomized trial of patients undergoing clean contaminated surgeries compared post surgical 
infection rates between those cleansed with chlorhexidine and those with povidine-iodine.  
They found that chlorhexidine decreased post-operative superficial wound infections by 50%19.  
Only 10% of the study population underwent non-abdominal gynecologic surgery, and the 
method of their vaginal preparation was not specified.  Though this article cannot be sited as 

Chlorhexidine vs Iodine 4 
setting the standard for vaginal preparation, it did change the general approach to skin 
preparation in the United States and helped support the superiority of chlorhexidine as an 
aseptic solution.   
 
A recent prospective quality improvement study, performed at an academic tertiary care center 
on patients of the gynecology oncology service undergoing cytoreductive surgery, reported 
their results after implementing a surgical site infection prevention bundle that involved 5 steps 
throughout the surgical process from pre-op to wound care.  One of these was vaginal 
preparation with 4% chlorhexidine.  Their baseline infection rate was reported as being 20%.  
Through their efforts, they decreased the post-operative infection rate to 3%9.  Due to the high 
baseline infection rate of their population as well as the multiple interventions employed within 
their bundle, the study provides further evidence of the likely superiority of chlorhexidine.  
 
The only randomized controlled trial performed to date comparing 4% chlorhexidine to 
povidone-iodine as a vaginal preparation was reported in 2005.  Discussing the true incidence 
of post-operative infection following hysterectomy and the exceedingly high number of 
participants that would be required to look at actual infection rates, the authors selected a 
surrogate marker of infection as their primary outcome.  They showed that chlorhexidine 
decreased bacterial colony counts in the vagina 40% more effectively than povidone-iodine 
thirty minutes from initial aseptic preparation.  The study was however underpowered at time 
points beyond 30 minutes and lacked specific information on pathogens within the reported 
cultures19.   
 
 Therefore, the purpose of our study is to use a randomized controlled trial to determine 
whether chlorhexidine is superior to povidone-iodine as an aseptic solution in the vagina by 
comparing its affects on bacterial count, change in common pathogens responsible for 
postoperative infection and colony counts throughout the time course of a hysterectomy.  
 
Research Plan  

Chlorhexidine vs Iodine 5 
• Study Design  
o Randomized Controlled Trial  
 
• Setting for the study 
o Patients of Cincinnati Urogynecology Associates and/or Tri-State Gynecology 
Oncology, TriHealth, Inc. undergoing total vaginal, laparoscopic assisted, total 
laparoscopic, or robotic hysterectomy at Good Samaritan Hospital or Bethesda 
North Hospital will be eligible for enrollment. 
o The study will be offered to those patients found to meet all inclusion criteria 
and none of the exclusion criteria via phone (see attached script), in office or 
prior to surgery in the preoperative holding area   
o Patient will sign Informed Consent and Authorization prior to surgery, but not to 
exceed 6 moths before surgery.    
o Following enrollment, a SNOSE (Sequentially-Numbered, Opaque, Sealed 
Envelopes) will reveal group allocation. 
 Intervention group:  
• Patients randomized to the chlorhexidine group will undergo 
presurgical vaginal aseptic preparation using 4% chlorhexidine 
solution. 
• Vaginal culture swabs will be collected following induction of 
general anesthetic, prior to their vaginal preparation. 
• Swabs will be collected subsequently at times marked 30 minutes, 
60 minutes and 90 minutes following preparation allowing for +/- 
5 minutes. 
• EPIC will be interrogated, looking at the time period from day of 
surgery to 30 days post operatively, for evidence of surgical site 
infections, including superficial incisional, deep incisional and 
organ space infections.  Incidents of surgical site infection will be 
determined by CDC guidelines44.  (see Appendix A) 
 

Chlorhexidine vs Iodine 6 
 Control group: 
• Those patients randomized to the povidone-iodine group will 
have their presurgical vaginal aseptic preparation performed 
using 10% povidone-iodine solution. 
• They will have culture swabs collected following induction of 
general anesthetic, prior to their vaginal preparation. 
• Swabs will be collected subsequently at times marked 30 minutes, 
60 minutes and 90 minutes from preparation allowing for +/- 5 
minutes. 
• EPIC will be interrogated, looking at the time period from day of 
surgery to 30 days post operatively for evidence of surgical site 
infections, including superficial incisional, deep incisional and 
organ space infections.  Incidents of true surgical site infection will 
be determined by CDC guidelines44. (Appendix A)    
• Participants 
o Study population: All women 18 years of age or older, who plan to undergo total 
vaginal, laparoscopically assisted vaginal, total laparoscopic, or robotic-assisted 
laparoscopic hysterectomy, with or without additional concomitant procedures 
by a physician at Cincinnati Urogynecology Associates or Tri-State Gynecology 
Oncology, TriHealth Inc. and will be approached for recruitment in their office or 
in the pre-operative holding area.   
o Inclusion/Exclusion criteria: 
 Inclusion 
• Adults 18 years of age and older 
• English speaking 
• Undergoing total vaginal, laparoscopic assisted vaginal, total 
laparoscopic, or robotic-assisted laparoscopic hysterectomy by a 
physician at Cincinnati Urogynecology Associates or Tri-State 
Gynecology Oncology TriHealth Inc.  

Chlorhexidine vs Iodine 7 
• Concomitant procedures such as vaginal vault suspension, 
suburethral sling, cystoscopy, enterocele repair, anterior or 
posterior colporrhaphy, bilateral salpingectomy or 
salpingooophorectomy, staging procedures, lymph node sampling 
and other indicated procedures will be included 
• Ability to provide consent 
 Exclusion 
• Unwillingness to participate in the study 
• Non English speaking 
• Patients that do not undergo a hysterectomy 
• Reported allergy to iodine or chlorhexidine preparation solutions 
• Patients undergoing planned debulking surgery for ovarian, 
fallopian tube or primary peritoneal cancers 
• Current infection necessitating hysterectomy 
• Active sepsis, pelvic abscess or pelvic inflammatory disease  
• Patient receiving Flagyl for treatment of vaginitis or for surgical 
prophylaxis during the perioperative period, including day of 
surgery. 
 
o Sample Size 
 Given the incidence of infection following hysterectomy, a surrogate 
outcome was felt to be necessary in order to complete the study in a 
timely fashion.  Therefore, using the only published randomized 
controlled trial, we selected contamination of the field as our outcome 
measure. 
 Contamination is defined as having >5000 bacteria within a culture19. 
 The previous study suggested a 22% difference in bacteria contamination, 
therefore our sample size was calculated to be 71 patients per arm to 

Chlorhexidine vs Iodine 8 
detect a 22% difference in cultures defined as contaminated at 90 
minutes from surgical preparation.  
 Power Analysis 
• Our calculation demonstrated need to enroll 60 patients in each 
arm based on the following: 
o A difference of 22% in number of cultures found to have >5,000 bacteria growing 
90 minutes from preparation 
o Significance at 0.05  
o Power at 80% 
o Odds ratio was 0.289 
o Assuming an estimated loss rate of 15%, the number of patient enrollment per 
arm was set to 71, for a total of 142 patients. [Attrition calculation: (60/0.85)] 
 Subjects will be randomized by using a random numbers table and sealed 
sequential envelopes prepared by an independent statistician.  Patients 
of Cincinnati Urogynecology Associates and Tri-State Gynecology 
Oncology will have independent randomization schedules.  
 
• Data Collection 
o Primary outcome: 
 The percent of samples considered contaminated at 90 minutes from 
preparation between groups. 
o Secondary Outcomes: 
 The percent of samples considered contaminated at 30 and 60 minutes 
from preparation between groups. 
 Number of samples reaching a bacterial load of 100,000 following vaginal 
preparation at any of the specified time points. 
 The change in bacterial count over time.  Specific attention will be given 
to investigate the following bacteria, most commonly identified in 
assocation with postoperative infections22,23:  

Chlorhexidine vs Iodine 9 
• Streptococcus Agalactiae 
• Staphylococcus aureus  
• Escherichia Coli 
• Gardnerella Vaginalis 
• Enterococcus Faecalis 
• Bacteroides Fragilis 
• Also included, specific bacteria associated with the condition of 
bacterial vaginosis22: 
 Gardnerella 
 Mobiluncus species 
 Prevotella 
 Bacteroides 
 Peptostreptococcus  
 The number of postoperative infections in each group 
o General Demographic Data 
 Age, BMI, race, past medical history, home medications, allergies , 
smoking history, prolapse stage, cancer stage, procedures performed, 
length of stay, surgical and postoperative complications, and estimated 
blood loss 
o Data Collection tool 
 A data collection tool will be utilized 
o Please see Appendix B for evidence regarding outcome measures 
 
• Intervention or experimental aspect of the study 
o Vaginal preparation 
 The vaginal scrub will be performed by the OR team according to 
standard procedures for asepsis within the TriHealth System  
 Solutions: 
• 4% chlorhexidine 

Chlorhexidine vs Iodine 10 
• 10% povidone-iodine 
o Sample Collection 
 Samples will be collected in a standard fashion in the operating room 
after the patient has been anesthetized 
• The ESwab liquid amies collection and transport system will be 
utilized. 
• The swab will be thoroughly rubbed along the vaginal surface in a 
circumferential pattern, careful to sample the entire surface of 
the vagina, beginning at the fornix and traveling towards the 
introitus for 10 seconds.  The sample will avoid the cervical os or 
peritoneum.   
• A sample will be collected prior to any vaginal preparation, at 30 
minutes, 60 minutes and 90 minutes from preparation (This last 
sample may be collected at end of surgery if prior to 90 minutes) 
• The samples will be labeled with the participant’s study ID, name, 
and time of collection, annotated as time 0, 30, 60, or 90. 
• The samples may be collected +/- 5 minutes around the 
determined time to allow for surgical flow and circumstantial 
adjustment.  
• Swabs will then be sent to the laboratory for analysis 
• An in-service will be provided to teach all participating physicians 
the standard method of collecting swabs as described above. 
 Laboratory Procedure Outline 
• Samples will be handled by a single technician within the 
laboratory.  This technician will be paid through study funds while 
they perform these duties.  
• The laboratory personnel will be blinded to the participants group 
assignment 

Chlorhexidine vs Iodine 11 
• Sterile calibrated loops will be used to inoculate the specimen 
onto specific agar for cultures: 
 Blood Agar 
 MacKonkey Agar 
 CAN Agar 
 Anaerobic Agars 
• Brucella 
• BBE/KUL 
• PEA 
• The inoculate will be streaked according to techniques commonly 
utilized in urine culture to facilitate analysis 
o TriHealth Laboratory\MIC\OAK\Procedures\Active\Cultures\Bacteriology\Urine 
Cultures.doc 
• The cultures will be read approximately 48-72hrs from inoculation 
• A colony count will be performed on each sample 
• Individual strains will be isolated and identified 
• The individual pathogens will be identified using the MALDI 
(Matrix Assisted Laser Desorption/Ionization-Time of Flight) test, 
by Bruker Daltonics.  
 An affordable & reliable bacterial identification 
method.  Based on mass spectrometry, using 
qualitative in vitro diagnostics, ribosomal proteins 
are analyzed and compared to two proprietary 
libraries for a match and identity verification. 
  Capable of identifying more than 200 organisms 
 http://www.midilabs.com/maldi-tof 
• Bacterial Vaginosis will be identified through a modified Nugent36 
method. 

Chlorhexidine vs Iodine 12 
 Utilizing colony counts obtained from culture plate 
reading and correlating this with specific identities 
found in the MALDI test, a Nugent score will be 
reported. 
• Nugent Score 
 Points will be awarded based on three 
morphotypes: 
• Medium to large gram positive rods 
• Small gram negative or variable rods 
• Curved gram negative or variable rods 
 Each of these morphotypes will be assigned a score 
based on their initial count: 
• 0 = No morphotypes 
• 1 = Less than 1,000 
• 2 = 1,000 – 4,000 
• 3 = 5,000 – 30,000 
• 4 = >30,000 
 The score for the three morphotypes is then 
added, and any score >7 is consistent bacterial 
vaginsosis, and a score <3 is normal flora.   
 Scores will be generated for each specific time 
point to allow trending following vaginal 
preparation. 
 Safety Considerations 
• Povidone-iodine is FDA approved for use as a vaginal scrub 
solution and is considered to be safe16. 
• Though this application would represent an off-label use, 4% 
chlorhexidine is considered a safe alternative to povidone-iodine 
for use as a surgical scrub of the vagina by the American College 

Chlorhexidine vs Iodine 13 
of Obstetricians and Gynecologists16.  TriHealth also includes 
chlorhexidine as a part of the standard surgical bundle.  
(Appendix C) 
• Statistical Analysis 
The primary outcome is the proportion of contamination (defined as having >5000 
bacteria within a culture) at 90 minutes from initial preparation. Logistic regression will 
be implemented to compare the odds ratio between two groups. Furthermore, multiple 
logistic regression will be utilized to test for confounding variables. For continuous 
variable, descriptive statistics will be reported with mean and standard deviation (or 
median and interquartile range). Difference between two groups will be evaluated in 
each time point by independent Student’s t-test or nonparametric equivalent (Mann 
Whitney-U test). Alpha < 0.05 will be considered statistically significant. 
 
Ethical Considerations 
• Informed consent  
o Patients who agree to participate in the study will sign a written informed 
consent. They will be consented by one of the stated investigators or trained 
study staff and they will receive a copy of the signed informed consent 
statements (ICS). A copy will be put in their medical file. 
• Privacy information 
o Extensive efforts will be made to ensure participant confidentiality and 
prevent unauthorized release of personal information. Electronic study 
documents will be stored on a secure drive and hard copy documents stored 
in a locked area.  Thereby, all identifying and protected health information 
will be maintained in a secure area at all times, accessible by authorized 
personnel only.  

Chlorhexidine vs Iodine 14 
o Study documentation, both electronic and hard copy will be stored securely 
per TriHealth’s Medical Records Retention Policy.  
 
• When and how will results be disseminated? 
 
 We plan for the results to be disseminated at a national meeting in the form 
of a poster or oral presentation. We also plan for the results to be published. 
 
 
 
 
 
 
 
 
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Chlorhexidine vs Iodine 17 
 
 
Appendix A 
CDC Guidelines on Diagnosis of Postoperative Infections44 
Superficial incisional SSI 
o Date of event for infection occurs within 30 days  
(where day 1 = the procedure date) 
 
o Involves only skin and subcutaneous tissue of the incision 
 
o patient has at least one of the following: 
o purulent drainage from the superficial incision 
o organism identified from wound sampling 
o superficial incision that is deliberately opened 
 AND 
• patient has at least one of the following signs or symptoms:  
o pain or tenderness;  
o localized swelling;  
o erythema; or heat. 
 
o Diagnosis of a superficial incisional SSI by the surgeon, attending* physician or 
other designee. 
 
*The term attending physician for the purposes of application of the NHSN SSI criteria may be 
interpreted to mean the surgeon(s), infectious disease, other physician on the case, emergency 
physician or physician’s designee.  
 
Deep Incisional SSI 
 
o Date of event for infection occurs within 30 days  
(where day 1 = the procedure date) 
 
o Involves the deep tissues of the incision (muscle/fascia) 
 
o The patient has one of the following: 
o Purulent drainage from a deep incision 
o A deep incision that spontaneously dehisces, or is deliberately opened or 
aspirated by a surgeon or attending physician* AND an organism is identified by 
sampling AND the patient has at least one: 
 Fever (>38C) 
 Localized pain 
 Localized tenderness 

Chlorhexidine vs Iodine 18 
o An abscess or other evidence of infection involving the deep incision that is 
detected on gross anatomical or histopathologic exam, or imaging test. 
 
 
*The term attending physician for the purposes of application of the NHSN SSI criteria may be 
interpreted to mean the surgeon(s), infectious disease, other physician on the case, emergency 
physician or physician’s designee.  
 
Organ Space SSI 
 
o Date of event for infection occurs within 30 days  
(where day 1 = the procedure date) 
 
o Infection involves any part of the body deeper than the fascial/muscle layers, that is 
opened or manipulated during the operative procedure 
 
o The patient has at least one of the following: 
o Purulent drainage from a drain that is placed into the organ/space 
(e.g., closed suction drainage system, open drain, T-tube drain, CT 
guided drainage). 
o Organisms identified from fluid or tissue in organ space 
o Abscess or other evidence of infection within the organ space detected grossly, 
from pathology or by imaging 
o Meets at least one criteria for the specific organ/space: 
 
o Intrabominal infections: 
 
Intraabdominal infections must meet at least one of the following 
criteria:  
 
1. Patient has organism(s) identified from an abscess or from purulent 
material from intraabdominal space by a culture or non-culture based 
microbiologic testing method which is performed for purposes of clinical 
diagnosis or treatment (e.g., not Active Surveillance Culture/Testing 
(ASC/AST).  
 
2. Patient has at least one of the following:  
 
a. abscess or other evidence of intraabdominal infection on gross 
anatomic or histopathologic exam  
 
b. abscess or other evidence of intraabdominal infection on gross 
anatomic or histopathologic exam  
 

Chlorhexidine vs Iodine 19 
AND  
 
organism(s) identified from blood by a culture or non-culture 
based microbiologic testing method, which is performed for 
purposes of clinical diagnosis or treatment (e.g., not Active 
Surveillance Culture/Testing (ASC/AST). The organism(s) identified 
in the blood must contain at least one MBI organism. See 
Appendix A of the BSI protocol:  
 
3. Patient has at least two of the following: fever (>38.0°C), nausea*, 
vomiting*, abdominal pain*, or jaundice*  
 
And at least one of the following:  
a. organism(s) seen on Gram stain or identified from fluid 
or tissue obtained during invasive procedure or from an 
aseptically-placed drain (e.g., closed suction drainage 
system, open drain, T-tube drain, CT guided drainage)by a 
culture or non-culture based microbiologic testing method 
which is performed for purposes of clinical diagnosis or 
treatment (e.g., not Active Surveillance Culture/Testing 
(ASC/AST).  
 
b. organism(s) identified from blood by a culture or non-
culture based microbiologic testing method which is 
performed for purposes of clinical diagnosis or treatment 
(e.g., not Active Surveillance Culture/Testing (ASC/AST). 
The organism(s) identified in the blood must contain at 
least one MBI organism(See Appendix A of the BSI 
protocol)  
 
AND  
 
imaging test evidence suggestive of infection (e.g., 
ultrasound, CT scan, MRI, ERCP, radiolabel scans [gallium, 
technetium, etc.] or on abdominal x-ray), which if 
equivocal is supported by clinical correlation (i.e., 
physician documentation of antimicrobial treatment for 
intraabdominal infection). 
  
o Vaginal Cuff Infections 
 
o Vaginal cuff infections must meet at least one of the following criteria:  
 

Chlorhexidine vs Iodine 20 
1. Post hysterectomy patient has purulent drainage from the 
vaginal cuff on gross anatomic exam.  
 
2. Post hysterectomy patient has an abscess or other evidence of 
infection at the vaginal cuff on gross anatomic exam.  
 
3. Post hysterectomy patient has organism(s) identified from fluid 
or tissue obtained from the vaginal cuff by a culture or non-
culture based microbiologic testing method which is performed 
for purposes of clinical diagnosis or treatment (e.g., not Active 
Surveillance Culture/Testing (ASC/AST). 
 
For further organ sites, or further details, the CDC site can be accessed for 
clarification. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Chlorhexidine vs Iodine 21 
 
Appendix B 
 
Rationale for Outcome Measures 
 
o Selecting Bacterial Count >5000 as cutoff 
  A pilot study26 completed by Culligan et al prior to their randomized 
trial19 describes their selection of >5000 bacteria or colony forming units 
(CFU) because it correlated with common cutoffs in other laboratory 
tests for bacterial contamination, specifically urinalysis26. 
 Earliest reports of the selection of 5000 colony forming units being used 
as a contaminate marker are found in literature from WWI, where 
soldiers being delivered to the field hospital who had a culture showing 
fewer than 5000 bacteria would have their wounds primarly closed27.  
 Some studies in both military and civilian literature reveal that a bacterial 
contaminant load of 10^5 is required within the wound site in order to 
lead to an infection following antibiotics and closure29,30 
 However, it has been shown that the presence of a foreign body within 
the wound can dramatically decrease the inoculate required to lead to 
infection, these studies are outlined below: 
• One of these was performed by Elek and Conen in the late 1950’s 
in an effort to determine the minimum dose of staphylococcus 
needed to cause wound infection.  They showed that the 
inoculate required dropped from 10^6 to 10^2 with the addition 
of suture27.   
• James built on their initial study with a robust animal model in 
1961.  They collected a total of 39 strains of staphylococci, then 
soaked suture material in broth with specific, different 
concentrations of staph.  They placed the suture through the skin 
of mice and watched for pus formation.  The tissues were 
harvested, slides prepared and actual inoculating dose of bacteria 

Chlorhexidine vs Iodine 22 
determined. They reported that a minimum bacterial count of 
1000-1500 was required to induce a wound infection in the 
setting of a foreign body, such as suture.  They further reported 
that their average true bacterial load introduced that lead to 
wound infection was between 3,200 and 4,800 bacteria28.    
 Further evidence of lower inoculate required for infection, specifically 
within the vagina is found in the symbiotic relationship rendered by 
mixed pathogens.  Facultative organisms, when combined with 
anaerobes, can create favorable conditions for overgrowth and lead to 
abscesses more readily than either alone31. 
 Therefore, the level of 5,000 is considered a reasonable threshold to 
utilize as one of contamination. 
 
o Selection of time window for culture collection 
 In the original pilot study reported by Culligan26, samples were collected 
prior to preparation, then at 30, 90, 150 and 210 minutes. Growth of 
bacteria dramatically dropped off following the 90 minute cultures.  Peak 
colony counts were identified between 30 and 90 minutes following 
preparation, suggesting a “weakest link” in standard infection 
prophylaxis.  
 In the randomized trial reported by Culligan19 the same trend was 
reported.  Highest contamination levels were seen at within the 30-90 
minute window.   
 Literature reporting on the average length of time required to complete a 
hysterectomy for benign indications varies in reported results32-35: 
Study 
TVH 
TAH 
LAVH 
TLH 
RTLH 
Chang 
80 
XX 
118 
XX 
XX 
Johns 
63 
XX 
102 
XX 
XX 

Chlorhexidine vs Iodine 23 
Shashoua 
XX 
XX 
XX 
122 
142 
Ribeiro 
78 
109 
XX 
118 
XX 
 
 Based on these average times, the window of highest contamination 
remains within the average length of most benign hysterectomies and 
therefore provides relevant clinical implication.  
 
o Rationale for Inclusion of BV analysis 
 A prospective case series detailing vaginal cultures from women 
undergoing benign gynecologic, urogynecologic and gynecology oncology 
surgeries.  The cultures were collected pre-operatively and were anylized 
using Nugent criteria. 27% of the women in this study were found to have 
bacterial vaginosis (BV) at presentation and 36% of these women 
developed a post-operative infection37. 
 Soper, one of the most quoted authors when discussing the relationship 
of BV and cuff cellulitis reported that patients with BV have a 3x higher 
risk of developing cuff cellulitis or abscess after abdominal hysterectomy 
compared to those with healthy vaginal flora38.  
 Another large series from the late eighties reported on patients with and 
without BV undergoing abdominal hysterectomy, and within this 
population, 35% of women with BV developed a postoperative cuff 
infection compared with 8% of women without BV39. 
 Finally, The American College of Obstetricians and Gynecologists 
recommends screening for BV prior to performing a hysterectomy to 
prevent postoperative cuff infections3. 
 
 
 
 

Chlorhexidine vs Iodine 24 
Appendix C 
Safety Considerations 
• In a large prospective trial performed in Kenya, women in labor had vaginal lavage 
with chlorhexidine on average 2 times during labor in an effort to decrease HIV 
transmission.  A total of 898 women underwent lavage with no adverse events40.  
• A large Swedish study compared chlorhexidine to placebo for vaginal lavage during 
labor.  2,238 women underwent vaginal lavage with chlorhexidine without adverse 
event contributed to the lavage41.  
• Another large, placebo-controlled randomized trial from Alabama, reported on 
vaginal lavage with chlorhexidine with over 500 women undergoing lavage without 
any maternal reactions to the solution42.  
• A review of the Swedish National Register for Gynecologic Surgery revealed that of 
the 43 hospitals included, none of them preferred povidone-iodine as a vaginal 
surgical scrub solution and the preferred solution was chlorhexidine43. 
• The only randomized trial comparing chlorhexidine to povidone-iodine for vaginal 
scrub reported zero adverse events19.