Measuring the common canal of a persistent cloaca: can MRI replace conventional imaging?

To evaluate the role of MRI in preoperative assessments of patients with a persistent cloaca and compare magnetic resonance imaging (MRI) versus fluoroscopy contrast study in the accuracy of common canal measurement and classification prediction.

Thirty-one patients with a persistent cloaca were diagnosed and treated at Guangzhou Women and Children's Medical Center between March 2011 and December 2017. The length of the common canal was measured using MRI and fluoroscopy contrast study. Classification results based on measurements were compared with cystoscopy and intraoperative findings. The accuracy in predicting the classification by measuring the common canal length was compared.

Among 31 patients, 24 had MRI, 24 underwent fluoroscopy contrast study, and 25 underwent cystoscopy. In 20 patients, MRI-based categorisations were in accordance with cystoscopy or surgery findings, whereas in four patients there was discordance. In 17 patients, categorisations based on fluoroscopy contrast study were in accordance with cystoscopy or surgery findings, and in seven patients there was discordance; the difference was not statistically significant (p>0.05).

MRI may accurately demonstrate genitourinary anomalies and the length of the common canal in patients with persistent cloaca. Categorisation based on MRI measurements of the common canal was accordant with the results from cystoscopy and findings from surgery. The use of this method may help surgeons to develop appropriate reconstruction plans before sending their patients to the operating room.