Rectal Examination in Children: Digital Versus Transabdominal Ultrasound

Purpose: We investigate 2 diagnostic tests to assess the rectal filling state. Materials and Methods: The rectal filling state was assessed with transabdominal ultrasound or with digital rectal examination by 2 independent investigators in children with urological problems before a scheduled diagnostic or surgical urological procedure. A dilated rectum filled with stool or large amounts of (usually) hard stool were both considered as a rectal fecal mass. All investigations were performed with the patient under general anesthesia. The kappa test was used to evaluate agreement between transabdominal ultrasound and digital rectal examination. Results: A total of 84 children (54 boys) with a median (p25-p75) age of 9.0 years (6.4-11) were eligible candidates. A rectal mass was found on transabdominal ultrasound and digital rectal examination in 32% and 41% of all children, respectively, with agreement between the 2 tests in 82.5%. Cohen's kappa showed good agreement of 0.62 (95% CI 0.45-0.79) between transabdominal ultrasound and digital rectal examination. The median (IQR) diameter of the rectum was 3.3 cm (2.8-3.9) in children with a full rectum, and 2.5 cm (1.8-2.8) and 2.0 cm (1.5-2.2) in patients with a half filled and empty rectum, respectively. Conclusions: Transabdominal ultrasound is a noninvasive and reliable alternative to assess the rectal filling state, and might replace digital rectal examination in the evaluation of children with constipation.