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5 Reproducibility of Colonic Transit Study in Patients with Chronic Constipation [2001년 1월 DCR] 2011-11-12 3110
 
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Young-Soo Nam, M.D., Alon J. Pikarsky, M.D., Steven D. Wexner, M.D.,
Jay J. Singh, M.D., Eric G. Weiss, M.D., Juan J. Nogueras, M.D.,
Jeong Seok Choi, M.D., Yong-Hee Hwang, M.D.
 
From the Department of Colorectal Surgery, Cleveland Clinic Florida, Fort Lauderdale, Florida
 
PURPOSE: Major therapeutic decisions are rendered based on a single colonic transit study. Therefore, the aim of this study was to assess the reproducibility of colonic transit time in patients with chronic constipation.
MATERIALS AND METHODS: Fifty-one patients with chronic idiopathic constipation were randomly selected to undergo two separate colonic transit tests. All clinical conditions, methodology, and patients' instructions were identical on both occasions.The gamma rate (linear correlation analysis) was
undertaken 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), the 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 colonic inertia, paradoxical puborectalis contraction, and chronic idiopathic constipation were 0.12, 0.21, and 0.60 (P < 0.01), respectively. Moreover, the success rate of colectomy for colonic inertia was significantly higher in patients who underwent a repeat transit study confirming inertia than in patients who underwent colectomy based on a single study.
CONCLUSIONS: Overall, colonic transit time is reproducible in patients with chronic constipation. The
correlation coefficient is best for patients with idiopathic constipation and worst for patients with colonic inertia. This new finding suggests that suboptimal surgical outcome may be attributable to inaccurate diagnosis. Because of this poor correlation coefficient, in patients with colonic inertia, consideration should be given to repeating the colonic transit study before colectomy to help secure the diagnosis
and improve outcome.
 
DISCUSSION
 
Severe constipation can be defined as a frequency of bowel movements of less than three per week for
more than six months and/or straining of stool more than 25 percent of the time and a failure to respond to medical treatment. 1' s There are many causes of constipation that can be assessed by anal manometry, etectromyography, cinedefecography, and colonic transit study9 Initially, Hertz et al. 25 reported a method of colonic transit study using bismuth as the tracer substance. Subsequently, Alvarez and Freedlander 26 used colored gIass beads, Burnett a7 used millet seeds, Mulinos 28 used carmine, Hansky and Connel129 used radioactive chromium, Hinton et al. 3° used radiopaque polyethylene pellets, Connell and Rowlands 3~ used a radiotelemetering capsule, and Rosswick et al. 32 used a radioisotope capsule. We currently use a commercially available radiopaque marker as 24 rings within a gelatin capsule. There are few reports about the reproducibility of colonic transit time. Ohe and Camilleri 33 reported that, although colonic transit studies were fairly reproducible in carefully selected patients, considerable discrepancy on two occasions approximately one year apart was described. Similarly, Bouchoucha et al. 34 reported that transit times were similar at first and second examinations one month apart. Authors have reported that the transit time of a single radiopaque marker was reproducible from day to day. In our study with a mean interval of 14 months between the two studies, overall the transit time was reproducible. However, the best reproducibility was found among patients with chronic idiopathic constipation, contributing to the significant correlation found; in patients diagnosed with colonic inertia, the correlation was poor. This finding emphasizes the importance of securing the diagnosis of colonic inertia before surgical treatment.
Indeed, the results of surgery for constipation vary dramatically even in the most recent literature. One major reason for this variability is that mechanisms of constipation are not clearly delineated before
surgery. There is little doubt that the key to selecting patients who will benefit from surgery is
objective physiologic testing. Therefore, the accuracy and reproducibility of these tests are of paramount
importance.
Prior publications have considered "success" based exclusively on resolution of laxative dependence and improved bowel frequency. By these parameters, the success rates in the current study were 100 percent in the group in whom the transit study was repeated two or more times and 90 percent in the group who had a single transit study (P = 0.34). Therefore, even a single transit study is as valuable as are repeated studies in predicting success of treatment of bowel frequency. However, for reasons that remain unclear, the group in whom two or more transit studies were performed still maintained 100 percent of "success"using our more stringent definitions (described in MATERIALS AND METHODS) whereas, in the patients who had only a single study performed, the success rate significantly decreased to 62 percent (P =0.03). Therefore, by "traditional" definitions, the overall success rate in the patients was 93 percent by resolution of bowel frequency and decreased cessation of the use of laxatives but only 73 percent if one also analyzes resolution of associated symptoms such as abdominal, pelvic, or anorectal pain or difficult evacuation. Thus, while performance of a single study
may allow surgery that corrects bowel frequency, repetition of the study and confirmation of colonic
inertia will help select patients in whom the associated symptoms will be less likely to persist after colectomy. One noted difference among the three groups studied is the male:female ratio. Both the coionic-inertia group and the paradoxical-puborectaliscontraction group had an equal gender distribution, whereas in the idiopathic-constipation group there was a strong female predominance. In this latter group, the correlation found between the two transit studies was the strongest, and perhaps a future evaluation of the differences in results and reproducibility of colonic transit studies in males and females is warranted.