Measure twice and cut once: Comparing endoscopy and 3D cloacagram for the common channel and urethral measurements in patients with cloacal malformations

Introduction: Precise and accurate measurement of the common channel and urethra is a critical determinant prior to the repair of cloacal malformations. Endoscopy and 3D reconstruction cloacagram are two common modalities utilized to help plan the surgical approach, however the consistency between these methods is unknown.

Methods: Common channel and urethral lengths obtained by endoscopy and 3D cloacagram of cloaca patients at six pediatric colorectal centers were compared. Data are given as mean (range).

Results: 72 patients were included in the study. Common channel measurements determined by 3D cloacagram and endoscopy were equal in 7 cases (10%). Endoscopic measurements of the common channel were longer than 3D cloacagram in 20 (28%) cases and shorter in the remaining 44 (62%) cases. The absolute difference between measurements of the common channel was 7.2 mm (0-2.4 cm). Urethral measurements by both modalities were equal in 8 cases (12%). Endoscopic measurement of the urethra was longer than that by 3D cloacagram in 20 (31%) patients and shorter in 37 (57%) of cases. The absolute difference between measurements of the urethra was 5.1 mm (0-2.0 cm). The reconstruction (e.g. TUM or urogenital separation) that would be performed according to measurements determined by 3D cloacagram and endoscopic measurements differed in 13/62 (21%) patients with each structure identified and common channel measurements of >1 cm.

Conclusion: Significant variation exists in the measurements of the common channel and urethra in patients with cloacal malformations as determined by endoscopy and 3D cloacagram. This variation should be considered as these measurements influence the decision to perform either a TUM or urogenital separation. Based on these findings, 3D cloacagram should be performed in all patients prior to cloaca repair to prevent mischaracterization of the malformation.

Level of evidence: Level IV.