Effect of preoperative fiber on postoperative bowel function: a randomized controlled trial

OBJECTIVE: To evaluate if pre‐operative fiber intake reduces time to first bowel movement after surgery for pelvic organ prolapse. METHODS: We performed an unblinded, randomized, controlled trial of women undergoing pelvic organ prolapse surgery between July 2019 and April 2021. Women > age of 18 were eligible if they were undergoing prolapse repair with or without hysterectomy. Women undergoing concomitant bowel surgery or sphincteroplasty were excluded, as were women with conditions affecting bowel function including inflammatory bowel disease, colorectal cancer, sigmoid resection or rectal surgery. Participants were recruited at their pre‐operative visit and randomized to receive either 3.4 g psyllium fiber supplementation twice a day for one week before surgery or no fiber supplementation prior to surgery. Randomization was blinded and performed using a 1:1 ratio and a block randomization scheme. Subject demographics and medications that could potentially cause constipation were recorded. Participants were asked to complete the Patient Assessment of Constipation Symptoms (PAC‐SYM) questionnaire as well as information about their bowel movement frequency and quality as per the Bristol Stool Scale. On the day of surgery, information was collected about the subject's last bowel movement, adherence to bowel regimen if randomized to intervention group, and procedure performed. Post‐operative bowel regimen was standardized for both groups with a standard escalation of treatment for constipation. Subjects completed a bowel diary for their first postoperative bowel movement after surgery characterized by the Bristol Stool Scale and any associated pain or urgency. They also recorded their daily postoperative pain using a Visual Analogue Scale (VAS). Total use of pain and bowel medications was captured. The primary outcome was time to first bowel movement. Secondary outcomes included pain associated with first bowel movement. Fisher's exact test and Student's t‐test were used to compare patient demographics. Adjusted linear regression was used for the primary outcome. RESULTS: 66 patients were enrolled in the study. 1 patient was readmitted with ileus, 3 patients withdrew from the study and 4 patients did not complete their bowel diaries, leaving 58 subjects for the final analysis. Demographic and perioperative characteristics were similar between the groups. There was no difference found between the groups with respect to time to first bowel movement (control: 91.7 hours versus intervention: 92.2 hours, P = 0.944). There was no difference found with pain associated with first bowel movement [VAS(range) control: 2.0 (0.0‐4.0) versus intervention: 2.5 (1.0‐5.0)]. With respect to urgency associated with first bowel movement after surgery and overall pain after surgery, there were no differences found. CONCLUSIONS: Pre‐operative fiber prior to prolapse surgery does not appear to improve time to first bowel movement after surgery.