The usefulness of ultrasound examination of the bowel as a method of assessment of functional chronic constipation in children

Abstract

Ultrasonographic assessment of stool retention in children with chronic constipation requires the diagnosis of megarectum. The aim of the study was to evaluate an atypical method of US assessment of megarectum, fecal impaction and enlarged colon in order to decide whether it can be used as an assessment method for children with functional chronic constipation. A total of 120 children with a positive diagnosis of chronic constipation were included in the study. All patients fulfilled the ROME II diagnostic criteria for defecation disorders. The control group comprised 105 patients with a normal defecation pattern. Children with a US diagnosis of megarectum, fecal impaction and enlarged colon were referred for proctoscopy and measurement of colonic transit time. The transverse diameter of the rectal ampulla increases with age and thus influenced the US measurements in both the patient and control groups. The numerical values of this parameter differed significantly between patients and controls in all age groups. The rectopelvic ratio is the ratio of the width of the rectal ampulla (as seen by US) to the distance between the anterior superior iliac spines (measured externally using a measuring tape). This allows the definition of megarectum. In the diagnosis of fecal impaction, US showed a sensitivity of 88.3% relative to proctoscopy. In children with fecal impaction the colonic transit time, average segmental transit time for the rectum and sigmoid colon, and average segmental transit time for the left colon were significantly longer. There was no statistically significant difference for the right side of the colon. US assessment of stool retention and overfilling of the colon in children with functional chronic constipation has a high correlation with proctoscopy findings and colonic transit time. The rectopelvic ratio can be used to diagnose megarectum in children with functional chronic constipation with a cut-off value of 0.189.