Obesity and bariatric surgery: a systematic review of associations with defecatory dysfunction

Obesity rates are rapidly growing in the developed world. While upper gastrointestinal disturbances and urinary incontinence are independently associated with obesity, the relationship between obesity and defecatory dysfunction is less well defined.

To summarize the literature on faecal incontinence, diarrhoea and constipation in obese patients and its effects of bariatric surgery.

A Medline search was carried out on articles published from January 1966 to March 2010.

Original articles on adult obese or morbidly obese patients were identified, including results following bariatric surgery that reported faecal incontinence, diarrhoea or constipation. Other forms of pelvic floor dysfunction were excluded. Main outcome measures included faecal incontinence, diarrhoea and constipation rates and their severity in obese patients and following bariatric surgery.

Twenty studies reported defecatory outcomes in obese patients (n = 14) and after bariatric surgery (n = 6). While constipation rates were similar, the rates of faecal incontinence and diarrhoea were higher in obese patients compared with non-obese patients. The exact rates of these conditions, and the correlations between body mass index (BMI) and faecal incontinence, diarrhoea and constipation, were not clear. Faecal incontinence improved after Roux-en-Y gastric bypass in studies with preoperative data. The effects of bariatric surgery on diarrhoea were unclear.

Few studies have assessed the correlations between obesity and defecatory function and the effect of bariatric surgery. Studies were often not well controlled and used non-uniform instruments to assess bowel function. Obesity appears to be correlated with higher rates of faecal incontinence and diarrhoea. The effects of bariatric surgery on these conditions are not well defined. Well-controlled studies correlating outcome with physiological pelvic floor function are needed.