Background Patients with anorectal malformations (ARMs) are at risk of renal anomalies, which may result in renal deterioration that can be asymptomatic. As a result, we have a protocol at our high-volume pediatric colorectal center to obtain annual renal ultrasounds (RUS) in all patients with ARM, regardless of symptoms or ARM complexity. Given that there is a direct correlation between the complexity of ARM and increased risk of renal abnormality, it is unknown if such aggressive screening is necessary for patients with mild ARM. Thus, we hypothesize that patients with mild ARM may not require a strict protocol. Methods We performed a single-institution review of patients managed at a large pediatric colorectal center from 2008 - 2023 with mild ARM (rectoperineal fistula, rectovaginal fistula, rectovestibular fistula, rectal/anal stenosis, and rectal atresia). We evaluated all ultrasounds completed in this cohort before and after surgical repair. Only patients with a renal ultrasound performed within 2 years of their primary surgical repair were included. A team of experienced urologists and urological advanced practice providers reviewed all RUS images and reports. Demographics and clinical variables were collected, and descriptive statistics were computed. Results There were 333 patients with mild ARMs, of whom 197 had a postoperative RUS within the first two years (Figure 1). The majority had a rectoperineal fistula (71.1%). Median age at anoplasty was 4.6 months [interquartile range (IQR): 2.2 - 9.0], and postoperative RUS was obtained at a median of 3.9 months after anoplasty [IQR: 2.4 - 11.0]. Most patients (70.1%) had a normal first postoperative RUS, and only four (2.0%) became abnormal on a subsequent screening RUS. Of these, only one patient (0.5%) was asymptomatic at the time of routine screening RUS and had a finding necessitating further intervention (Table 1). Patients with an initially normal postoperative RUS underwent a median of 3 further RUS [IQR: 2-4], with 33 patients (24.6%) undergoing five or more normal RUS. Overall, the number of patients with a normal postoperative RUS needed to be screened yearly to find one asymptomatic renal anomaly was 197. Conclusion In a large cohort of patients with mild ARM, only one patient (0.5%) benefited from screening RUS and had a renal anomaly requiring intervention. This data shows that if a RUS after the primary repair of a mild ARM is normal, additional screening of the asymptomatic patient is not necessary.
