Reproducibility of colonic transit study in patients with chronic constipation

PURPOSE: Major therapeutic decisions are rendered based on a single colonic transit study. Therefore, the aim of this study was to assess the reproduc ibility of colonic transit time in patients with chronic constipation. MATE RIALS AND METHODS: Fifty-one patients with chronic idiopathic constipation were randomly selected to undergo two separate colonic transit tests. AU cl inical conditions, methodology, and patients' instructions were identical o n both occasions. The gamma rate (linear correlation analysis) was undertak en between the first and second colonic transit times. Groups were divided according to the diagnoses of colonic inertia (slow-transit constipation), paradoxical puborectalis contraction, and chronic idiopathic constipation ( normal-transit constipation). RESULTS: In 35 of 51 patients (69 percent), t he results were identical between the two studies; however, in 16 patients (31 percent), the results were disparate (gamma correlation coefficient = 0 .53; P < 0.01). The specific correlation coefficients for patients with col onic inertia, paradoxical puborectalis contraction, and chronic idiopathic constipation were 0.12, 0.21, and 0.60 (P < 0.01), respectively Moreover, t he success rate of colectomy for colonic inertia was significantly higher i n patients who underwent a repeat transit study confirming inertia than in patients who underwent colectomy based on a single study. CONCLUSIONS: Over all, colonic transit time is reproducible in patients with chronic constipa tion. The correlation coefficient is best for patients with idiopathic cons tipation and worst for patients with colonic inertia. This new finding sugg ests that suboptimal surgical outcome may be attributable to inaccurate dia gnosis. Because of this poor correlation coefficient, in patients with colo nic inertia, consideration should be given to repeating the colonic transit study before colectomy to help secure the diagnosis and improve outcome.