Upper urinary tract anomalies in patients with persistent cloaca: Prevalence, phenotype, and associations with...

Upper urinary tract anomalies (UTAs) in patients with persistent cloaca are incompletely characterized. We aimed to define the prevalence and spectrum of UTAs and identify associated clinical and anatomic features.

We performed a single-institution cohort study using a prospective database of patients with persistent cloaca (2020-2025). Patients undergoing primary cloacal repair were included. The outcome was any UTA identified on preoperative imaging, including the cloacagram. Component-level analyses evaluated high-grade vesicoureteral reflux (HG-VUR; grades III-V), high-grade urinary tract dilation (HG-UTD; SFU grades 3-4), and solitary kidney. Covariates include demographics, anatomic characteristics, and comorbidities.

Of 101 patients with persistent cloaca seen at our institution, 50 underwent primary repair. UTAs were identified in 44 patients (88%). The most common anomalies were HG-VUR in 29 (58%), HG- UTD in 20 (40%), and solitary kidney in 15 (30%). Complex cloaca (where CC ≥ 3 cm) was present in 21 patients (42%) and was associated with UTAs (100% vs. 79%, p = 0.03). The median CC length was longer in those with UTAs (2.8 vs. 1.4 cm, p < 0.001). Patients with HG-VUR had longer CC length compared to those without HG-VUR (4.6 vs. 2.2 cm, p = 0.04) and poor sacral ratio (9/12, 75% vs. 12/38, 32%; p = 0.01). HG-UTD was associated with CC length (4.6 vs. 1.9 cm, p = 0.001), shorter urethral length (1.1 vs. 2.1 cm, p = 0.003), and urethral atresia (5/6, 83% vs. 5/22, 23%; p = 0.05). Solitary kidney was linked to urethral atresia (5/6, 83% vs. 5/22, 23%; p = 0.01), vaginal atresia (7/9, 78% vs. 8/41, 20%; p < 0.001), and Müllerian agenesis (6/7, 86% vs. 9/43, 21%; p = 0.002). Notably, most solitary kidney cases (13/15, 87%) had an ipsilateral UTA.

UTAs cluster with increasing cloacal complexity, supporting a shared developmental basis rather than isolated pathology. Associations with common channel (CC) length, sacral development, and urethral anatomy suggest that more severe cloacal phenotypes confer greater upper tract disease burden. The strong relationship between solitary kidney and ipsilateral anomalies identifies a subgroup with limited renal reserve and structural risk, with implications for early risk stratification and surveillance. While known neonatal factors such as hydrocolpos may contribute to early urinary tract changes, these findings emphasize an underlying anatomic driver of risk.

UTAs are highly prevalent in patients with persistent cloaca and are associated with anatomic complexity. Patients with solitary kidney frequently have additional ipsilateral anomalies, identifying a subgroup at risk for adverse renal outcomes.