Assisted bladder emptying following cloacal repair: The importance of common channel length

Patients with persistent cloaca frequently require assisted bladder emptying (ABE) after repair, but the pathophysiology leading to this requirement is incompletely understood.

To identify factors associated with ABE and describe urodynamic studies (UDS) after primary reconstruction.

We reviewed a single institution prospective database of patients referred for persistent cloaca (both primary or post-reconstruction evaluations) and included those undergoing primary repair at our institution from 2020 to 2025. The primary outcome was ABE at most recent follow-up with post-operative UDS collected when available. Descriptive statistics and logistic regression were performed.

Of 105 patients evaluated, 53 underwent primary repair at our institution. The median age at repair was 8 months (IQR 7-18) with median 34-month follow-up (IQR 14-52). Median common channel (CC) length was 2.4 cm (IQR 1.6-4.4) and urethral length was 1.8 cm (IQR 1.0-2.2). Twenty-one (40%) had complex anatomy (CC ≥ 3 cm). Twenty-four (45%) had a spinal cord abnormality. Based on the anorectal malformation index [1], 7 (13%) had poor-risk spine anatomy and 8 (15%) had poor-risk sacral anatomy. Urogenital separation (UGS) was performed in 29 (55%). At most recent follow-up, 47% (25/53) required ABE. Those requiring ABE had longer CCs (4.4 v. 1.7 cm, p < 0.01), shorter urethras (1.3 v. 2.2 cm, p < 0.01) and more commonly underwent UGS (80% [20/25] v. 32% for those voiding spontaneously [9/28], p = 0.001), while rates of spinal cord abnormalities were similar (48% v. 43%, p = 0.71). On multiple logistic regression adjusting for UGS and poor-risk spinal cord or sacral anatomy, CC length was independently associated with ABE, and each 1-cm increase doubled the odds of ABE (OR 2.0, 95%CI 1.3-3.6, p = 0.008). UDS were performed in 28 patients. For the overall sample, median functional capacity was 72% of estimated bladder capacity, median detrusor leak or end fill pressure was 6 cm H₂O (IQR 3-12) and 20 (71%) had incomplete emptying.

CC length was independently associated with ABE requirement. UDS found that bladders commonly had low-risk storage pressures but poor emptying and required ABE due to retention and urinary tract anomalies. This data suggests that abnormal bladder development among the most severe malformations may influence ABE requirement, even in the absence of significant spinal cord/sacral abnormalities.

Nearly half of patients required ABE after cloaca repair. This was independently associated with CC length. While most had low-risk storage parameters on UDS, poor contractility and emptying commonly required ABE especially with the frequency of urinary tract anomalies.