The diagnostic yield of colonoscopy in patients with isolated abdominal pain

Colonoscopy is an overstretched resource and there is no consensus on whether isolated abdominal pain is an appropriate indication for colonoscopy. We evaluated the proportion of patients referred for colonoscopy with isolated abdominal pain and determined the diagnostic yield for this indication.

All patients registered as having a colonoscopy at Waitemata District Health Board on Endoscribe reporting database between March 2005 and February 2010 were included. Patients were recruited based on the indication for colonoscopy of: abdominal pain, iron deficiency anaemia or overt rectal bleeding. All investigations and electronic clinical documents for patients with abdominal pain were retrieved and patients with concurrent anaemia, rectal bleeding, weight loss, altered bowel habit, abdominal mass, previous abnormal investigations and history of inflammatory bowel disease or bowel malignancy were excluded. The diagnostic yield between the 3 study groups were compared using Chi-squared test, Wilcoxon rank sum test and multiple logistic regression models.

Total of 10,052 colonoscopies were performed of which only 2,633 fulfilled our inclusion criteria. The abdominal pain group accounted for 1.2% of colonoscopies performed and had the lowest diagnostic yield of 48.8% (P<0.001). Among those with abdominal pain, significant neoplasia was found in 3.3% and was significantly lower than those with iron deficiency anaemia or overt rectal bleeding groups (P<0.001). When segregated by age, the abdominal pain group continued to have significant less neoplasia (3.8%, P=0.001) among those 50 and older but no difference was found among younger patients.

A small proportion of colonoscopy resources are being used to investigate isolated abdominal pain, which is appropriate given the low diagnostic yield of significant pathology, particularly amongst those less than 50 years old.