Purpose: To evaluate bowel management for children with colorectal pathology by measuring transverse rectal diameter (TRD) and assessing fecal load with transabdominal rectal ultrasound (TRU). Methods: Prospective case–control study of children receiving bowel management (BM) between 04/2023 and 04/2024 was done. There was inclusion of patients with Hirschsprung disease (HD), anorectal malformation (ARM) and functional constipation (FC). Patients with other congenital or neurological conditions were excluded. Control group consisted of inpatients and outpatients without abdominal complaints. FC was diagnosed according to ROM-IV-criteria. For HD and ARM, we followed a list of symptoms. To assess fecal load, we visualized the TRD using the Klijn (Klijn et al. in J Urol 172:1986–1988, 2004) method. The bladder was moderately full. The fecal load was assessed retrograde from the rectum. Follow-up was at 1/3/6 months. Secondary data were collected from medical records. Sample size calculated a priori and follow-up group with new gathered data. Results: p value for TRD in all groups significant with p < 0.05 and in grouped follow-up. Conclusion: Ultrasound is a useful tool for assessing fecal load and helps diagnose constipation and monitor BM. Irrespective of colorectal pathology, a cut-off of 3 cm seems to discriminate between children without constipation/overload symptoms and asymptomatic patients. We present a radiation-free method for monitoring bowel management.

Background: Constipation and outlet obstruction may persist after successful pull-through in Hirschsprung Disease (HD). The radiographic assessment of the faecal load is widely used but exposes the child to radiation. This study aims to evaluate whether the transrectal diameter (TRD) assessed with ultrasound correlates with symptoms of faecal load and whether the TRD normalises when symptoms disappear. Method: Children with HD after pullthrough and functional constipation presenting to our colorectal clinic between 4/23 and 4/24 were assessed for symptoms of constipation, smearing and outlet obstruction, as well as healthy controls. Ultrasound measurement of the TRD was conducted. Bowel management was initiated according to our institutional pathway using Peristeen© irrigation after an orthograde disimpaction regime. Results: A total of 193 children underwent TRD assessment. Of 60 children with HD, 26 (43.3%) presented with obstructive symptoms, and 34 (56.7%) were asymptomatic. In asymptomatic patients with HD, the mean TRD of 2.26 cm (SD 0.61) was significantly (p < 0.001) lower than in HD with symptoms, with a mean TRD of 3.35 cm (SD 1.03). Individuals without colorectal pathology had a mean TRD of 2.04 cm (SD 0.37), and children with functional constipation and symptoms showed a mean TRD of 4.36 cm (SD 1.32). The mean TRD after symptom resolution was 2.37 cm. Conclusions: Children with HD without obstructive symptoms have a TRD < 3 cm, as do controls. The transrectal diameter allows the clinician to sonographically assess the faecal load in children with HD at the bedside without radiation. The TRD is useful for monitoring a bowel management program in children with HD.

Introduction: Children with anorectal malformations (ARM) frequently experience impaired bowel function and require long-term bowel management. Assessment of fecal load commonly includes abdominal radiographs, which provide information on overall stool distribution but may require repeated imaging and are subject to interobserver variability. Ultrasound measurement of the transrectal diameter (TRD) has been proposed as a radiation-free adjunct in functional constipation, but evidence in children with ARM remains limited. This study aimed to evaluate point-of-care ultrasound (POCUS) measurement of TRD as an adjunct to clinical assessment for evaluating fecal load and monitoring bowel management in children with ARM. Methods: In this prospective observational cohort study, children with ARM attending a tertiary colorectal clinic between April 2023 and January 2025 underwent standardized ultrasound assessment of TRD as part of a structured bowel management program. Findings were compared with children with functional constipation (FC) and healthy controls. TRD measurements were correlated with clinical symptoms of constipation and soiling. Receiver operating characteristic (ROC) analysis was performed. Results: Fifty-seven children with ARM (mean age 5.7 years) were included, alongside 53 children with FC and 72 controls. Asymptomatic ARM patients demonstrated TRD values comparable to controls (2.20 vs. 2.05 cm, p = 0.246), whereas symptomatic ARM patients showed significantly increased TRD (3.64 cm, p < 0.001). ROC analysis identified a TRD cut-off of 3.1 cm with a sensitivity of 63.3% and specificity of 96.3%. During structured bowel management, TRD decreased below this threshold in parallel with clinical improvement. Conclusion: POCUS measurement of TRD is a feasible, radiation-free adjunct to clinical assessment in children with ARM. While it does not replace radiographic evaluation of global colonic stool burden, it may support monitoring within structured bowel management programs.