Transabdominal ultrasound of rectum as a diagnostic tool in childhood constipation

PURPOSE: We tested whether transverse rectal diameter measured by ultrasound could identify rectal impaction, investigated whether transverse diameter is enlarged in constipated children compared to healthy children and evaluated transverse diameter during treatment of constipation.

MATERIALS AND METHODS: A total of 51 children 4 to 12 years old were included in the study. Of the children 27 (mean age 7.0 +/- 1.8 years) had been diagnosed with chronic constipation by Rome III criteria and 24 (9.1 +/- 2.7 years) were healthy controls. All patients underwent a thorough medical history and physical examination, including digital rectal examination and measurement of rectal diameter by transabdominal ultrasound. Constipated children underwent repeat investigations after 4 weeks of laxative treatment.

RESULTS: Average rectal diameter of children with negative digital rectal examination was 21 +/- 4.2 mm (mean +/- SD), leading to the approximation that a value greater than 29.4 mm (mean +/- 2 SD) indicates rectal impaction. All children with rectal impaction identified by digital examination had a rectal diameter larger than 29.4 mm. Moreover, constipated children had a significantly larger rectal diameter (42.1 +/- 15.4 mm) than healthy children (21.4 +/- 6.0 mm, p <0.001). After 4 weeks of laxative treatment constipated children had a significant reduction in rectal diameter (mean 26.9 +/- 5.6 mm, p <0.001).

CONCLUSIONS: Transverse rectal diameter seems to be a valuable tool to identify rectal impaction and may replace digital rectal examination. Constipated children have a significantly larger rectal diameter compared to healthy children, and when constipation is treated the diameter is reduced significantly.