Edenfield, Autumn L. MD; Amundsen, Cindy L. MD; Weidner, Alison C. MD; Wu, Jennifer M. MD, MPH; George, Amy MD; Siddiqui, Nazema Y. MD, MHSc
Nearly 25% of women in the United States have pelvic floor disorders, and the lifetime risk of undergoing a surgical procedure for pelvic organ prolapse (POP) or urinary incontinence (UI) is 11% by 80 years of age.1,2 Approximately 200,000 women undergo surgery annually for POP and thus the estimated direct costs of POP surgery are over $1 billion per year.3–5 Recent projections estimate that the number of women undergoing surgery for POP will increase to approximately 250,000 by 2050.6
Uterosacral ligament suspension is a common vaginal procedure for apical prolapse. It uses sutures placed in the intermediate uterosacral ligament, at or above the ischial spine, which are affixed to the vaginal apex.7,8 Reported failure after uterosacral ligament suspension has ranged from 10% to 19% in any vaginal compartment whether anterior, apical, or posterior.8–11 A recent systematic review found success for the anterior, apical, and posterior compartments after uterosacral ligament suspension is 81.2%, 98.3%, and 87.4%, respectively.11
Obesity is a known risk factor for the development and progression of POP.1,12,13 However, there are limited and conflicting data regarding whether higher body mass index (BMI, calculated as weight (kg)/[height (m)]2) is a risk factor for recurrence after POP surgery.14–18 Furthermore, it is unclear whether BMI may be a risk factor for recurrent vaginal prolapse after vaginal apical suspension procedures. This is a particularly timely issue to evaluate given that obesity represents a major public health issue with 64.1% of adult women in the United States being overweight or obese.19
Given these limitations in the existing literature, our primary objective was to estimate the risk of recurrent prolapse in any vaginal compartment after uterosacral ligament suspension among normal-weight women compared with overweight or obese women. We also sought to estimate other risk factors for recurrent vaginal prolapse and assess the anatomic characteristics of recurrent prolapse after uterosacral ligament suspension.
MATERIALS AND METHODS
We performed a retrospective cohort study of women who underwent uterosacral ligament suspension at Duke University Medical Center from December 1, 1996, through June 30, 2011, after Duke University School of Medicine institutional review board approval was obtained. We included all women who underwent uterosacral ligament suspension for symptomatic prolapse and who were followed for at least 6 months after surgery. We included only those who underwent uterosacral ligament suspension by a vaginal approach and excluded those with a history of previous vault suspension. We compared two cohorts: 1) normal weight (BMI 18.5–24.9) compared with 2) overweight (BMI 25.0–29.9) and obese (BMI 30.0 or greater). We also performed a subanalysis comparing outcomes across all three groups by BMI classification: normal weight, overweight, and obese. Those without complete BMI data were unable to be classified into cohorts and therefore were excluded.
We reviewed medical records and collected data regarding demographics, medical and surgical history, concurrent procedures, estimated blood loss, perioperative complications, POP quantification examinations, and length of follow-up. Surgical history and the presence of diabetes, constipation, pulmonary disease, and tobacco use were elicited from the comprehensive evaluations performed during the initial office consultation.
Our primary outcome was a composite measure including recurrent prolapse in any vaginal compartment defined as anterior, posterior, or apical prolapse extending beyond the hymen with straining (POP quantification points Ba, C, Bp greater than 0) or repeat treatment for prolapse with surgery or pessary. Given that obesity increases the risk of the development and progression of prolapse, we hypothesized that the cohort of overweight or obese women would have a higher risk of recurrent vaginal prolapse after uterosacral ligament suspension than the cohort of normal-weight women.1,12,13 For our secondary outcomes, we were interested in assessing additional risk factors for recurrent prolapse as well as the most common anatomic site of recurrence after uterosacral ligament suspension. Uterosacral ligament suspension procedures were performed based on the attending surgeon's preferred technique regarding number of sutures per side and suture material used. During this 15-year period, nine different attending surgeons performed uterosacral ligament suspension procedures. The types of suture material and number of sutures used did not change significantly throughout the study period. Although techniques were not standardized across surgeons, they were all performed with a vaginal approach according to techniques described in the literature using sutures placed in the intermediate uterosacral ligament, at or above the ischial spine, which are affixed to the vaginal apex, typically considered a “high” uterosacral suspension.7,8 Data regarding uterosacral ligament suspension technique, including suture material and number, as well as concomitant procedures were collected.
Data analysis was performed with IBM SPSS Statistics 20.0. Continuous variables were analyzed using the Student’s t test or Mann-Whitney U test, and categorical variables were analyzed using χ2 or Fisher's exact tests. Multivariable logistic regression analysis was also performed to adjust for potential confounders. Known a priori risk factors for recurrent prolapse and significantly different baseline characteristics between our two cohorts were included in our model as potential confounders. For our sample size calculation, we estimated that recurrence in a nonobese population was 15%8–10 and a clinically significant difference between our two cohorts would be a difference of threefold in recurrent prolapse from an estimated 15% to 45%. Thus, using a 2:1 ratio of overweight or obese to normal weight, we needed at least 186 women (124 overweight or obese women and 62 normal-weight women) to detect a difference between 15% and 45% recurrence with a significance level of .05 and power of 80%.
We identified 236 women who underwent uterosacral ligament suspension during the study period with at least 6 months of follow-up after surgery. Seventeen women were excluded as a result of incomplete height or weight information, or both, leaving 219 women who were included for analysis. Of the 219 women, 81 (37%) were normal weight with a mean BMI of 23.0±1.4 and 138 (63%) women were overweight or obese with a mean BMI of 30.5±4.7 (Table 1). Compared with the normal-weight cohort, the overweight or obese cohort was more likely to be younger (mean age 61.5±10.1 years compared with 64.8±10.2 years, P=.02), currently use tobacco (8% compared with 0%, P=.01), and have a higher median estimated blood loss (100 mL with interquartile range 100–200 mL compared with 150 mL with interquartile range 100–250 mL, P=.02). In contrast, the overweight or obese cohort was less likely to undergo concomitant posterior repair (34.1% compared with 53.1%, P=.01). There were no significant differences with respect to other preoperative variables (Table 1), and the follow-up interval was similar in normal-weight and overweight or obese cohorts (14 months [interquartile range 8.5–26.5 months] compared with 13 months [interquartile range 9.0–29.0 months], P=.98).
There were no differences among intraoperative or postoperative complications between groups; among the total cohort, there were seven urinary tract injuries (3.2%) with two ureteral injuries (0.9%) and five cystotomies (2.3%). One case was complicated by a hemorrhage requiring transfusion. Eight women (3.7%) were followed postoperatively for neuropathic pain related to the uterosacral ligament sutures, and four (1.8%) patients had the uterosacral ligament suspension sutures ultimately released as a result of the pain. Regarding intraoperative variables specifically, there were no differences in number of uterosacral ligament suspension sutures placed, type of suture material used, concomitant anterior or posterior repair, or concomitant stress UI procedure (Table 1).
Using our composite outcome measure, overall recurrent prolapse after uterosacral ligament suspension occurred in 24.7% (54/219 women). The risk of recurrence among the 81 normal-weight women was 22.2% (95% confidence interval [CI] 14.5–32.5%, n=18), and the risk among the 138 overweight or obese women was 26.1% (95% CI 19.4–34.0%, n=36) and was not a statistically significant difference (relative risk 1.17 with 95% CI .72–1.93, P=.52). Variables including race, diabetes, constipation, tobacco use, prior or concomitant hysterectomy, prior prolapse surgery, number of uterosacral ligament suspension sutures placed, type of suture material used, concurrent anterior repair, concurrent posterior repair, and concurrent stress UI procedure were not associated with increased risk of recurrence (P>.05 for all). To assess for potential confounders, we also performed a multivariable logistic regression analysis. After adjusting for age, race, constipation, prior POP surgery, prior hysterectomy, and concurrent anterior or posterior repair, there remained no significant differences in risk of recurrent prolapse after uterosacral ligament suspension between our two cohorts (odds ratio 1.28, 95% CI 0.63–2.58).
We also wanted to investigate any differences in the risk of recurrent prolapse after uterosacral ligament suspension among all three groups of BMI classification: normal weight, overweight, and obese. Therefore, we performed a subanalysis across all three BMI groups to further assess for risks of recurrent prolapse. In this analysis, there were no differences in the risk of recurrent prolapse among normal-weight (n=18/81 [22.2%]), overweight (n=23/73 [31.5%]), and obese (n=13/65 [20.0%]) women (P=.24).
The overall risk of undergoing subsequent surgery for recurrent prolapse was 15.1% (n=33). The risk among normal-weight women was 16.0% (95% CI 9.5–25.7%, n=13 women), whereas the risk among overweight or obese women was 14.5% (95% CI 9.5–21.4%, n=20 women), which was not statistically significant (relative risk 0.90 with 95% CI .48–1.72, P=.76). One patient was briefly treated with a pessary for recurrent apical and posterior prolapse 14 months after uterosacral ligament suspension, but she underwent repeat surgery within 3 months of using the pessary.
The most common site of anatomic recurrence was the anterior compartment (Table 2). Anatomic anterior prolapse recurred in 13.6% (95% CI 7.6–22.9%, n=11 women) of the normal-weight women and in 19.6% (95% CI 13.8–27.0%, n=27) of the overweight or obese women (relative risk 1.44 with 95% CI 0.76–2.75, P=.26). Of the 38 women with anterior prolapse after uterosacral ligament suspension, 63.2% (n=24) of those had undergone a concurrent anterior repair with the initial uterosacral ligament suspension. Of the normal-weight women, 9.9% (n=8) had recurrent apical prolapse, whereas 8.0% (n=11) of the overweight or obese women had apical recurrences (P=.63). Anatomic posterior prolapse recurred in 7.4% (n=6) of the normal-weight women and in 6.5% (n=9) of the overweight or obese women (P=.80). Of the normal-weight women, 6.2% (n=5) had prolapse recurrence in both the apical and anterior compartments, whereas this occurred with 5.1% (n=7) of the overweight or obese women (P=.73).
Given the variable follow-up times among our patients, we performed a Kaplan-Meier survival analysis (Fig. 1). Based on the log rank test, there were no significant differences in prolapse recurrence between the normal-weight and overweight or obese women (P=.53).
Kaplan-Meier surviva...Image Tools
We found that with at least 6 months of follow-up after uterosacral ligament suspension, the risk of recurrent POP was 24.7% based on a composite outcome definition of any anatomic prolapse beyond the hymen or pessary or repeat surgery for POP. In our population, the risk of reoperation for recurrent POP after uterosacral ligament suspension was 15.1% with at least 6 months of follow-up. Between normal-weight and overweight or obese women, there were no statistically significant differences in risks of anatomic recurrence or reoperation for recurrent POP. We also found the most common site of anatomic recurrence was the anterior compartment with 17.4% of women having an anterior prolapse recurrence.
The strengths of our study include the large study population over a 15-year study period with relatively long follow-up. Our cohort study also benefits from detailed preoperative and serial postoperative objective anatomic data along with surgical history, medical comorbidity, and perioperative information. Given that a variety of surgeons was performing the uterosacral ligament suspension procedures over the 15 years with an array of tailored approaches to the procedure, we believe our findings are generalizable to a range of current uterosacral ligament suspension techniques.
Our data are limited by our retrospective, single-institution approach. In particular, our data could be skewed by follow-up bias toward higher recurrence given that patients who are doing well are not as likely to return for follow-up over the long term. Another limitation to our data is the lack of rigorous subjective measures from which a true composite outcome could be assessed.
Across both cohorts, we found low apical recurrence of 8.7%; however, we were not powered to primarily investigate this compartment-specific recurrence. Published literature has largely reported overall vaginal prolapse recurrence.8–10 Our overall recurrence risk of 24.7% is higher than the generally quoted recurrence risk after uterosacral ligament suspension in the literature of 10–19%.8–11 This may likely be the result of difference in follow-up intervals or the follow-up bias skewing toward a higher recurrence. In addition, the majority of our patients underwent uterosacral ligament suspension procedures with delayed absorbable sutures. In our study, there was no increase in prolapse recurrence with type of suture material used, although we were not powered to investigate this. Chung et al20 recently showed that with short-term follow-up after a uterosacral ligament suspension procedure, the failure with permanent suture is 1% compared with 6% with delayed absorbable suture. The majority of recurrent prolapse in our study occurred in the anterior vaginal wall, and it is unclear to what extent suture material choice may affect this particular compartment, but the 8.7% apical recurrence in our cohort closely reflects the 6% risk seen by Chung et al.20
Importantly our primary outcome did not include an assessment of prolapse symptoms. Barber et al21 found that treatment success after POP surgery varies dramatically based on outcome definition used and that unlike anatomic success alone, the absence of vaginal bulge symptoms is significantly associated with overall improvement. Barber et al21 also discussed that the hymen is a pivotal “cutoff point” and that symptoms are less likely with prolapse at or within the hymen, which is the rationale behind our anatomic outcome definition.
The most common site of recurrence after uterosacral ligament suspension in our cohort is the anterior compartment with 17.4%. Similar to our study, in a systematic review of success after uterosacral ligament suspension, Margulies et al11 found the compartment with the lowest success is the anterior compartment with success of 81.2%. Rooney et al22 showed that apical prolapse is most strongly correlated to anterior vaginal wall prolapse. The anterior wall is a susceptible anatomic location for recurrent POP23 and given the close association of apical and anterior prolapse,22 it is not surprising that the most common site of recurrence after uterosacral ligament suspension is the anterior wall.
Our study did not find a statistical difference between normal-weight and overweight or obese women in terms of recurrent POP, reoperation for recurrence, or anatomic site of recurrence. Bradley et al showed no difference in the risk of recurrent prolapse 2 years after sacral colpopexy in normal-weight compared with obese women.14 Clark et al and Denman et al showed that BMI was not associated with reoperation after surgery for POP, UI, or both after 5 and 10 years of follow-up, respectively.15,17 Salvatore et al18 found that BMI greater than 30 was not associated with increased recurrence after POP surgery, although they did exclude those with apical vaginal prolapse greater than stage I after a previous hysterectomy. However, Diez-Itza et al16 showed an increased risk of prolapse recurrence after vaginal surgery for POP with increased body weight. Our results are similar to these prior findings but significantly add to the literature because prior studies did not specifically investigate vaginal apical suspension or uterosacral ligament suspension. An important area for future study of the relationship of BMI to recurrent prolapse after vaginal surgery includes prospective long-term follow-up with both high-quality anatomic data and rigorous validated subjective outcome measures for a true composite assessment.
Overall we found there is no difference in prolapse recurrence between normal-weight and overweight or obese patients after uterosacral ligament suspension with an overall recurrence of 24.7% and with 15.1% of patients undergoing reoperations for recurrent prolapse. The most common site for anatomic prolapse recurrence is the anterior vaginal compartment followed by the apical compartment with the least likely site for recurrence being the posterior compartment. The uterosacral ligament suspension procedure should be considered an apical suspension with reasonably low anatomic recurrence in both normal-weight and overweight or obese women.
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