Decreasing Postoperative Pain Following Endometrial Ablation: A Randomized Controlled Trial
Phase: NA
Conditions: Postoperative Pain
Sponsor: Christiana Care Health Services

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Title: Decreasing Postoperative Pain Following Endometrial Ablation:  A Randomized 
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Controlled Trial 
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Principal Investigator: Jordan Klebanoff, MD 
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Sub-Investigator: Nima Patel, MD 
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Epidemiologist/Analyst: Nancy Sloan, DrPH 
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Purpose: To determine whether paracervical injection of long acting local anesthesia 
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decreases postoperative pain following endometrial ablation under general anesthesia. 
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Background:   
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Destruction of the endometrial lining to control bothersome uterine bleeding 
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has been implemented since 1937 (ACOG Committee on Practice Bulletins, 2007).  
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Currently there are various different ‘second generation’ energy sources to avert such 
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bleeding, five of which are now approved in the United States (ACOG Committee on 
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Practice Bulletins, 2007).  These 5 second generation devices include:  
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Thermachoice/Cavaterm, which use high temperature fluid within a balloon; Microsulis, 
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which applies microwaves; Novasure, which uses bipolar energy; Hydrothermablator, 
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which uses free fluid at high temperatures; ELITT, which uses laser thermotherapy; and 
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HerOption, which uses cryoablation.   Patient selection for endometrial ablation is 
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crucial, as it is intended for premenopausal women with normal uterine cavities and no 
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desire for future fertility that are affected by heavy menstrual bleeding.  Since the 
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introduction of the initial ‘second generation’ device in 1997 these modalities have 
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overtaken the industry mostly due to their ease of use and shorter operative times.  
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Regardless, a Cochrane review finds insufficient evidence to prove superiority of these 
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newer modalities over the traditional ‘gold standard’ resectoscopic technique (Anne 
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Lethaby, 2013). 
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Endometrial ablation has been demonstrated in a variety of settings including 
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outpatient surgical centers as well as physician’s offices.  Evidence suggests that 
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microwave endometrial ablation under local anesthesia is a safe and acceptable practice 
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(Wallage S, 2003).  Very often, when endometrial ablation is performed as an outpatient 
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procedure, patients are pre-medicated and then receive a paracervical injection of local 
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anesthesia to control pain intraoperatively (Mark H. Glasser, 2009).  When endometrial 
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ablations are performed as an outpatient procedure through a surgical center, a variety 
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of anesthesia techniques are employed depending on the infrastructure and human and 
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institutional resources available.  These techniques may vary from conscious sedation to 
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general anesthesia, all of which have been proven to be acceptable methods. 
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In this center endometrial ablations are performed as an outpatient procedure 
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under general anesthesia with a variety of induction techniques and intraoperative pain 
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management practices.  According to physician preference, patients may receive an 
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additional paracervical injection of local anesthetic before the procedure, immediately 
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after, or not at all.  To date, there are no studies evaluating the efficacy of local 
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anesthetic in addition to general anesthesia for patients receiving endometrial ablation 
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to guide physician practice. The purpose of this study is to evaluate the efficacy of local 
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anesthetic, in addition to general anesthesia, in our large, community-based patient 
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population, in meaningfully decreasing postoperative pain. 
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Methods:  
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This study will be a single center prospective single blind randomized controlled 
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trial of premenopausal women undergoing endometrial ablation.   This study will take 
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place in the Christiana Hospital outpatient surgical center.  Patients will include English 
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speaking premenopausal women aged 30 – 55 scheduled to undergo outpatient 
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endometrial ablation in the surgical center.  These patients will be recruited either in 
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physician’s offices, by telephone based on surgical scheduling, or on the day of their 
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procedure.  All consents will be signed in person.   
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   Study Design: 
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Frequently, providers will give their patients additional analgesia in the form of a 
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local anesthetic injected as a paracervical block, either before or after the completion of 
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the procedure with the hope of reducing postoperative pain.  This practice is not 
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standardized, as its efficacy has never been evaluated in the setting of endometrial 
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ablation under general anesthesia.   
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The purpose of this study is to assess the efficacy of this additional local 
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anesthesia upon completion of endometrial ablation under general anesthesia.  
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Patients, once consented, will be randomized in blocks of 6 to either the treatment 
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group or control groups.  Those randomized to the treatment group will receive a 
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paracervical injection of 20 mL 0.25% Bupivacaine at the completion of the procedure 
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(Howard W. Jones III, 2008).  Patients randomized to the control group will receive an 
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equal volume injection of normal saline with the same paracervical technique.  
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Paracervical injection will be standardized to include a total dose of 20 mL divided into 
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four 5 mL injections at the 2, 4, 8, and 10 o’clock positions on the cervix (Howard W. 
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Jones III, 2008).  Paracervical block will be given at the completion of the endometrial 
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ablation. 
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Only the patients and PACU staff will be blinded to the injected solution.  Once 
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general anesthesia has been induced the circulating nurse will open the study patient’s 
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unique randomization sequence and the appropriate study solution will be drawn in the 
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operating room.  The endometrial ablation procedure will be performed by the surgeon 
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in accordance with that surgeon’s specific preference for technique and device.  Upon 
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completion of the procedure, and before general anesthesia is reversed, the 
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paracervical injection of the patient’s unique study solution will be administered as 
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described above.  The operating room team including the surgeon, anesthesiologist, and 
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ancillary staff will be aware of the injected solution’s contents.  The post anesthesia care 
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unit (PACU) staff responsible for assessing immediate and delayed postoperative pain 
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will not be aware of the contents of the injected solution, except when necessary for 
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any unexpected complication, in which case the pharmacist maintaining the 
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randomization coding will break the code for that particular patient.  All patients will 
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receive IV Toradol with completion of the procedure and have a standardized rescue 
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analgesia protocol in place in the postoperative care unit setting in accordance with the 
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current practice described above.  Per the nursing protocols postoperative pain will be 
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assessed using 10 point Visual Analog Scale (VAS) and if patient’s pain is above or equal 
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to a 5, on the 10 point scale, they may receive additional analgesia in the form of 
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intravenous (IV) medication or by mouth tablets (PO).  Pain scores, as well as rescue 
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analgesic administered, is routinely recorded by the nursing staff and converted to a 
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patient’s electronic health record.   
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Due to the infrastructure set up, at CCHS outpatient endometrial ablations are 
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performed under general anesthesia with the patients asleep for the entire procedure.  
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Per the standard surgical center protocol postoperative patients will be assessed 
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regularly for postoperative pain.  If the patients express pain equal to or beyond a 
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predetermined threshold of 5, on a visual analog pain scale from 0 through 10, they may 
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receive rescue analgesia.  Patients are taken directly from the operating room to the 
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PACU where their pain is assessed on arrival by trained nursing staff.  Patients are kept 
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in Phase 1 of recovery for a minimum of 30 minutes, and a minimum of 30 minutes in 
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Phase 2 before discharge following general anesthesia.  At a minimum a postoperative 
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patient’s pain is assessed every 10 minutes in Phase 1, and every 15 minutes in Phase 2.  
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Patients are candidates for rescue analgesic medications, generally in the form of 
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Dilaudid or Fentanyl, if their pain score is greater than 5 out of 10.  In Phase 1 pain 
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medication is generally given in IV form whereas in Phase 2 pain medication is usually 
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given PO. 
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Figure 1: Visual Analog Scale 
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Upon discharge all patients will be given two additional 10 point VAS forms and 
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will be instructed to complete these two pain assessments at 4 hours and 8 hours after 
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their surgery.  These pain scales will be labeled before discharge with the patient's study 
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identification code, date, the times they are to be completed, and instructions to retain 
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the forms until they have spoken with the study staff on the following day.  Each patient 
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will be discharged with an additional prescription for twelve tablets of Tylenol #3.  Each 
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patient will then be contacted on the day following their surgery by a study investigator 
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to record the patient’s home pain scores as recalled by the patient by use of the two 
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pain scales completed at 4 hours and 8 hours postop.  Each patient will also be asked to 
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disclose how many of the twelve Tylenol #3 tablets they have remaining.   
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Primary Outcome:  
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We propose to test a 40% decrease in the mean 10 point VAS postoperative pain score 
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at 1 hour after the operation.  This percent decrease is based on a separate IRB 
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approved retrospective chart review of the most recent patients who underwent an 
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endometrial ablation at the Christiana Hospital surgical center. This retrospective chart 
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review found that of the last twenty patients who underwent an endometrial ablation, 
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without any additional local anesthesia in the form of a paracervical block, the mean 
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postoperative pain score at 1 hour was 2.85± 2.21.  The 40% hypothesized reduction in 
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pain is equivalent to approximately 1 full point on the VAS scale and felt to be a clinically 
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meaningful decrease at the lower end of the VAS scale that could influence policy and 
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practice. The average standard deviation between the mean 1 hour postoperative pain 
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scores between the reviewed charts of the 20 patients receiving a paracervical block 
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and the 20 that do not was 1.78, approximately equal to 75% of the average mean pain 
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scores for the 40 patients who did and did not receive a paracervical block.  Using a two 
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tailed test, a Type I error of 5% and statistical power of 80%, and an average standard 
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deviation equal to 75% of the average VAS scores in both groups, the study requires a 
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sample of 36 patients per study group.  Assuming a 15% attrition rate this study requires 
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42 patients per study arm (84 total participants).  Enrollment in this study will occur for 
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10 months, or until the number of participants needed per study group is met, 
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whichever occurs first.    This allows at least 2 months for data analysis and report 
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composition.  Enrollment will be monitored by the Principal Investigator (Klebanoff) 
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monthly, to gauge when enrollment should stop.  To ensure ongoing enrollment of 
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similar numbers of participants in each study group, randomization in blocks of 2 will be 
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used, so that for each 2 patients enrolled, 1 will be assigned to each study group. 
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Secondary outcomes: The study will also conduct descriptive analyses of the study 
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group differences in postoperative pain scores at 4 and 8 hours following surgery, 
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amount of rescue analgesia required postoperatively, but before discharge, time to 
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discharge, postoperative nausea/vomiting requiring medication, blood loss, and amount 
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of narcotic remaining at postoperative day one.  
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Data Points: 
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Covariates 
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- age 
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- race/ethnicity 
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- Insurance type 
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Mediating variables 
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- BMI (height/weight) 
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- Indication for surgery 
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- surgeon (anonymous code) 
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- type of ablation 
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- cervical dilation 
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- type and number of previous surgeries 
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- intra-operative complication incidence 
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Outcomes 
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- 1 hour postop VAS pain score (primary outcome) 
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- 4 and 8 hours postop VAS pain score (secondary outcomes) 
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- blood loss 
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- time to discharge 
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- type and amount of postop opioid given 
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-postop anti-emetics given 
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- postop complication incidence 
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Inclusion criteria: English speaking premenopasual women, aged 30 – 55, undergoing 
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outpatient endometrial ablation at the CCHS SurgiCenter for menorrhagia, abnormal 
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uterine bleeding, or thickened endometrium. 
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Exclusion criteria:  
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Known malignancy   
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Weight < 50 Kg 
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Amide allergy     
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History chronic pain 
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Cardiac arrhythmia   
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Dilaudid/codeine allergy 
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History of opioid use    
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Inability to take PO Opioids 
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Uterine anomaly    
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Previous ablation   
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Concomitant laparoscopic surgery 
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Primary language other than English 
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Data analysis: Continuous variables will be assessed using Student's t-tests and 
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categorical variables will be assessed using the chi-square tests with Fisher's exact 
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significance levels should there be fewer than 5 observations in any cell.  Non-
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parametric tests may be used to compare median values of continuous variables. Linear 
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and logistic regressions will be conducted on continuous and categorical outcomes, to 
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adjust for any unexpected differences in covariates and to describe mediation of effect. 
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All data will be maintained on a CCHS server accessible only to those members of the 
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research team.  All information will be coded based on the patients unique study 
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number. 
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Works Cited 
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ACOG Committee on Practice Bulletins. (2007, May). www.acog.org. Retrieved 09 21, 
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2015, from http://www.acog.org/Resources-And-Publications/Practice-
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Bulletins/Committee-on-Practice-Bulletins-Gynecology/Endometrial-Ablation 
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Anne Lethaby, J. P. (2013). Endometrial resection and ablation techniques for heavy 
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menstrual bleeding . Retrieved September 2015, from The Cochrane Library: 
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http://www.thecochranelibrary.com 
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Cohen, J. (1977). Statistical power analysis for the behavioral sciences. New York: 
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Academic press. 
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Howard W. Jones III, J. A. (2008). Te Linde's Opertive Gynecology Eleventh Edition (Vol. 
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11). Philadelphia, PA: Wolters Kluwer. 
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Mark H. Glasser, M. P.-Y. (2009, June). Office Endometrial Ablation with Local 
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Anesthesia Using the HydroThermAblator System: Comparison of Outcomes in 
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Patients with Submucous Myomas with Those with Normal Cavities in 246 Cases 
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Performed Over 51⁄2 Years . The Journal of Minimally Invasive Gynecology, 700-
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707. 
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Wallage S, C. K. (2003, September). A Randomised Trial Comparing Local Versus General 
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Anaesthesia for Microwave Endometrial Ablation. The British Journal of 
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Obstetrics and Gynaecology, 799-807. 
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Sample Postoperative Home Pain Scores 
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Patient Sticker 
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Study identification code # 
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Your surgery was completed at: Time and Date 
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Please rate your pain at:  Time and Date 
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Please rate your pain at:  Time and Date 
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Please retain this form until you have spoken with a member for the study team on the 
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day following your surgery. 
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