RESULTS: Compared with controls, patients with minimal to mild and moderate to severe endometriosis had a higher prevalence of symptoms consistent with IBS (0% vs 65% and 50%, respectively, p<0.001) with significantly lower mean pain thresholds (39.5 mm Hg (95% CI 36.0 to 43.0) vs 28.1 mm Hg (95% CI 24.5 to 31.6), p=0.001 and 28.8 mm Hg (95% CI 24.9 to 32.6), p=0.002) not explained by differences in rectal compliance.