Incidence and risk factors of early postoperative small bowel obstruction in patients undergoing hysterectomy for benign indications

Abstract

Small bowel obstruction (SBO) is a major cause of postoperative mortality and morbidity following abdominal and pelvic surgery, with 225,000-345,000 annual admissions. SBO may be classified based on onset from day of surgery. Early SBO occurs within the first 30 days following surgery, whereas late SBO occurs after the initial 30-day postoperative window. The majority of either type of bowel obstruction is believed to be secondary to intra-abdominal adhesions. Early SBO warrants special attention because of the difficulty in distinguishing between mechanical and nonmechanical obstruction during this period. Whereas conservative management often leads to resolution of nonmechanical obstruction and some partial SBO, surgical management is associated with a higher rate of complications compared to surgery for late SBO because of the presence of hypervascular adhesions in the early postoperative period. The current literature regarding SBO, and early SBO in particular, following hysterectomy is limited. Given that approximately 400,000 hysterectomies are performed annually, understanding the risk factors associated with SBO following these types of surgeries is imperative for improving patient outcomes. The objective of this study was to evaluate the incidence of and risk factors for early small bowel obstruction (SBO) after hysterectomy for benign indications. This was a retrospective cohort study using data from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database from 2014 to 2016. Current Procedural Terminology codes were used to identify patients undergoing hysterectomy for benign indications with or without concomitant colpopexy, lysis of adhesions (LOA), adnexectomy, or appendectomy. Data on patient demographics and clinical and surgical factors were obtained. Patients were then stratified into those with and those without SBO. Pairwise comparison was performed using the Wilcoxon rank-sum test and Fisher exact tests. Multivariable logistic regression was used to identify significant independent predictors of SBO. Of 47,937 hysterectomies, SBO occurred in 286 patients, at a rate of 5.9 per 1000 hysterectomies. Comparing patients with and without SBO, those with an obstruction were older (49 vs 46 years, P<.001) and were more likely to smoke (21.0% vs 15.8%, P= .02), to have a history of prior abdominal surgery (73.4% vs 65.4%, P= .005), and to have medical comorbidities such as hypertension and dyspnea. Patients experiencing SBO were also more likely to undergo abdominal hysterectomy (72.0% vs 21.2%, P < .001), adhesiolysis (5.2% vs 2.1%, P < .001), appendectomy (1.7% vs 0.5%, P= .02), and cystotomy repair (1.0% vs 0.3%, P= .002). After logistic regression, route of hysterectomy was not a significant risk factor for SBO, whereas wound class ≥3 (adjusted odds ratio [aOR], 5.96; 95% confidence interval [CI], 2.71-12.99) and perioperative transfusion (aOR, 5.01; 95% CI, 3.54-7.13) were the most significant risk factors. Additional risk factors for early SBO included nonwhite race (aOR, 1.84; 95% CI, 1.33-2.48), increasing age (aOR, 1.04; 95% CI, 1.02-1.05), prior abdominal or pelvic surgery (aOR, 1.49; 95% CI, 1.17-2.03), operating times >170 minutes (aOR, 1.90; 95% CI, 1.37-2.58), uterine weight >250 g (aOR, 1.54; 95% CI, 1.11-2.14), lysis of adhesions (aOR, 2.10; 95% CI, 1.23-3.66), and concurrent appendectomy (aOR, 2.64; 95% CI, 1.06-6.65). Early SBO is a rare complication of benign hysterectomy. Although route of hysterectomy was not found to be a significant risk factor for early SBO, variables typically associated with abdominal hysterectomy compared to minimally invasive hysterectomy, including higher wound class, larger uteri, and perioperative transfusion (a marker of intraoperative blood loss), were strongly correlated with subsequent development of early obstruction.