Radionuclear transit to assess sites of delay in large bowel transit in children with chronic idiopathic constipation.

Purpose: Chronic idiopathic constipation (CIC) with soiling in children may result from slow colonic transit (SCT) or anorectal dysfunction and/or psychological problems known as functional fecal retention (FFR). Evidence is accumulating that SCT and FFR need different treatments, but they are poorly distinguished by solid marker studies. The authors used radionuclear transit scintigraphy to categorize children with CIC as having either FFR or SCT.

Methods: Children (N = 101) with CIC (and soiling) who were referred for further investigation after failure of standard treatments (diet, laxatives) received radiolabeled colloid orally, and scintillation images were collected at 0 to 2, 6, 24, 30 and 48 hours (total radiation dosage = 2 standard x-rays). Radioactivity in 6 regions (precolonic, ascending, transverse, descending, rectosigmoid, and evacuated feces) was measured, and the median position (geometric center) of radioactivity at each time was determined.

Results: In children, meals normally reach the cecum at 6 hours and are evacuated in 30 to 58 hours. Fifty patients had retention of radioactivity in the proximal colon at 48 hours, indicating SCT. Analysis of the images and the geometric center showed that passage through the ascending colon and transverse colon was delayed in SCT. In 24 patients, radioactivity was passed by 30 hours, indicating normal transit or possible FFR. Twenty-two patients had retention in the rectum, indicating definite FFR. Five studies were borderline.

Conclusions: Radionuclear transit scintigraphy is useful for categorizing patients with CIC as having either FFR or SCT, allowing for different treatments. Radionuclear transit scintigraphy provides more detail and greater sensitivity than solid marker studies in diagnosing CIC. Radionuclear transit scintigraphy showed that half of our patients had SCT.