MRI of acquired posterior urethral diverticulum following surgery for anorectal malformations

Abstract

Background: Posterior urethral diverticulum (PUD) is one of the most common postoperative complications associated with anorectal malformation (ARM) correction. Objective: To describe our MRI protocol for evaluating acquired PUD following ARM surgery, and associated imaging findings. Materials and methods: Two radiologists retrospectively reviewed 61 pelvic MRI examinations performed for postoperative ARM for PUD identification and characteristics. Associated clinical, operative and cystoscopy reports were also reviewed and compared to MRI. Results: An abnormal retrourethral focus suspicious for PUD was identified at MRI in 13 patients. Ten of these patients underwent subsequent surgery or cystoscopy, and PUD was confirmed in five. All of the confirmed PUD cases appeared as cystic lesions that were at least 1 cm in diameter in two imaging planes. Four of the false-positive cases were punctate retrourethral foci that were visible only on a single MRI plane. One patient had a seminal vesical cyst mimicking a PUD. Conclusion: Pelvic MRI can be a useful tool in the postoperative assessment of suspected PUD associated with ARM. Radiologists should have a high clinical suspicion for a postoperative PUD when a cystic lesion posterior to the bladder/posterior urethra is encountered on two imaging planes in these patients. © 2011 Springer-Verlag.