Purpose: Small intestinal bacterial overgrowth (SIBO) is a condition associated with irritable bowel syndrome (IBS) and a variety of autonomic symptoms. The SIBO breath test has been found to be positive in 84% of patients with IBS vs 20% of controls. We hypothesized that SIBO would be more prevalent in patients with IBS-like symptoms who have undergone previous abdominal surgery due to adhesions and potential for stasis.
Methods: A retrospective review of patients from a tertiary colorectal surgery clinic was performed to identify patients with SIBO considered in the differential diagnosis. Demographics, past medical and surgical history, presenting symptoms, and diagnostic evaluations were recorded. SIBO-positive patients were compared SIBO-negative patients in case-control fashion. Multiple regression analysis was performed to identify etiologic factors for SIBO.
Results: Seventy subjects were identified during a 36-month period (2004-2007). 18 patients were excluded due to noncompliance with testing, and 2 were excluded due to a decision to treat for SIBO without formal testing. Common presenting symptoms included chronic abdominal pain (52%), bloating (46%), constipation (66%), and diarrhea (12%). Mean symptom duration was 45 months (range 2-216). Mean age was 52 years (range 17-91), weight 152 lb (range 93-264), and 86% were female. The majority of patients were Caucasian (81%) and Hispanic (17%). 80% of patients had previous abdominal surgery, mean 2 procedures (range 0-6), 18% of which involved foregut, 12% midgut, 27% hindgut, and 43% female reproductive organs. Prior surgery was performed laparoscopically in 20% of patients vs open in 80%. 8% of patients had a history of small intestinal obstruction. 76% of patients tested positive for SIBO, 78% with previous surgery vs 70% without previous surgery. SIBO-positive patients were older than SIBO-negative patients: mean age 56 vs 44 yrs, (p< 0.01). Logistic regression analysis did not reveal any clinically significant independent factors associated with SIBO. Symptoms resolved in 50% of patients treated with GI tract antibiotics.
Conclusions: SIBO is very common in a colorectal surgery population presenting with lower GI complaints. Although a past history of abdominal and pelvic surgery was not associated with a statistically higher incidence of SIBO, the high prevalence of SIBO-positive breath tests was greater than historical control rates. While further study is needed to assess the risk of SIBO after abdominal surgery, SIBO should be considered in the differential diagnosis of patients with normal anatomic findings and chronic lower gastrointestinal complaints.