The Effects of Bariatric Procedures on Bowel Habit

Bariatric procedures are increasingly being used to combat the rising obesity epidemic. The aim of this study was to assess the effect of these interventions on bowel habit.

We recruited obese adults listed for a bariatric procedure. Demographic data, medical history, medications and anthropometric measurements were recorded. Bowel habit was characterized using a 7-day Bristol Stool Form Scale (BSFS) diary. A validated food frequency questionnaire (FFQ) was used to assess diet.

Twenty-six patients were assessed pre-operatively and at a median of 6.4 months post-operatively. Nineteen had a Roux-en-Y gastric bypass (RYGB), five had a sleeve gastrectomy (SG) and two had an intra-gastric balloon (IGB) with median percentage excess weight loss (% EWL) of 67.9, 52.4 and 31.3 %, respectively. Dietary fibre intake decreased from 24.4 (±12.1) g/day pre-operatively to 17.5 (±7.3) g/day post-operatively (P = 0.008). Frequency of bowel motions decreased from 8.6 (±3.5) to 5.7 (±3.5) motions/week (P = 0.001). Mean usual BSFS score decreased (towards firmer stool) from 4.1 (±1.3) pre-operatively to 3.1 (±1.9) post-operatively (P = 0.016). Constipation increased from 8 to 27 %, but this did not reach statistical significance (P = 0.125).

Constipation is a common problem after bariatric surgery. The decrease in bowel motion frequency and change towards firmer stools suggest prolonged intestinal transit time after bariatric procedures. Reduction in dietary fibre intake is likely to be a contributory factor.