Ghoshal Uday C, Gupta Dinesh, Kumar Ashok, Misra Asha
Department of Gastroenterology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, Uttar Pradesh, India.
Natl Med J India. 2007 Sep-Oct;20(5):225-9.
Constipation is a common problem, which may be due to slow transit or faecal evacuation disorders. Though the screening test of colonic transit study using radio-opaque markers given at 0, 24 and 48 hours followed by abdominal X-ray at 72 hours is a good protocol in the West, it is not suitable for Indians who have a rapid gut transit.
Nine patients with adult Hirschsprung disease, 11 with chronic intestinal pseudo-obstruction diagnosed using standard investigations and 11 healthy subjects were evaluated by colonic transit study using radio-opaque markers (SGmark), 20 each at O, 12 and 24 hours followed by an abdominal X-ray at 36 and 60 hours. The cut-off was determined by using receiver operating characteristic (ROC) curves, and sensitivity, specificity, positive and negative predictive values and diagnostic accuracy were determined.
The total number of markers retained in the abdomen and those in the right segment at 36 hours in patients with Hirschsprung disease and chronic intestinal pseudo-obstruction was higher than that in healthy subjects though the number in the left and rectosigmoid segments were comparable. The abdominal X-ray at 60 hours, total number of markers and number in all segments were higher in patients with Hirschsprung disease and chronic intestinal pseudoobstruction than in healthy subjects. The best cut-off by ROC curves at 36 and 60 hours was 30 and 14 markers, respectively. The sensitivity, specificity, positive and negative predictive values, diagnostic accuracy and area under the ROC curve at 36 hours were 90%, 82%, 90%, 82%, 87% and 0.9, respectively; the corresponding values at 60 hours were 95%, 100%, 100%, 92%, 97% and 0.99, respectively.
Using the proposed protocol, the colonic transit study is able to distinguish patients with specific motility disorders causing constipation such as Hirschsprung disease and chronic intestinal pseudo-obstruction from healthy subjects with reasonable sensitivity and specificity, and shows that an abdominal X-ray at 60 hours is better than one at 36 hours.
便秘是一个常见问题，可能是由于肠道传输缓慢或粪便排出障碍所致。虽然在西方，通过在0、24和48小时给予不透X线标志物，随后在72小时进行腹部X线检查来进行结肠传输研究的筛查试验是一个很好的方案，但它并不适用于肠道传输较快的印度人。
对9例成人先天性巨结肠患者、11例经标准检查诊断为慢性假性肠梗阻的患者以及11名健康受试者进行结肠传输研究，使用不透X线标志物（SGmark），分别在0、12和24小时各给予20个，随后在36和60小时进行腹部X线检查。通过绘制受试者工作特征（ROC）曲线确定截断值，并计算敏感性、特异性、阳性和阴性预测值以及诊断准确性。
先天性巨结肠和慢性假性肠梗阻患者在36小时时腹部留存的标志物总数以及右半结肠的标志物数量高于健康受试者，尽管左半结肠和直肠乙状结肠段的标志物数量相当。在60小时时，先天性巨结肠和慢性假性肠梗阻患者的腹部X线检查、标志物总数以及所有肠段的标志物数量均高于健康受试者。ROC曲线在36和60小时时的最佳截断值分别为30个和14个标志物。36小时时的敏感性、特异性、阳性和阴性预测值、诊断准确性以及ROC曲线下面积分别为90%、82%、90%、82%、87%和0.9；60小时时的相应值分别为95%、100%、100%、92%、97%和0.99。
采用所提出的方案，结肠传输研究能够以合理的敏感性和特异性将患有导致便秘的特定动力障碍的患者（如先天性巨结肠和慢性假性肠梗阻患者）与健康受试者区分开来，并且表明60小时时的腹部X线检查比36小时时的更好。
