Distal urethral plate adhesions: New anatomical perspective in hypospadias

Abstract

Introduction: We found midline epithelial adhesions in the glandar urethral plate in patients with hypospadias. After dissolution, a blind epithelized channel becomes visualized inside of the plate pointing to immature embryonic luminization. In addition it reveals that the epithelized surface of the distal urethral plate is larger than previously considered.

Objective: To determine the incidence and extent of these new anatomical details of urethral plate in hypospadias patients.

Methods: We prospectively assessed the detailed anatomy of the urethral plate in 72 consecutive patients with hypospadias. We recorded the presence of adhesions in the middle of the glandar urethral groove that can be easily dissoluted (dissolution line - D-line). We recorded the plate width before and after D-line dissolution, the presence of the hidden blind channel at continuation of D-line (channel type-A) and of the visible blind channel between D-line and urethral hypospadiac meatus (type-B) (Figure). In 62 patients, where the urethral plate tubularization was considered (Duplay, TIP), septs between channels were opened in the midline and a final width of the plate was measured by rolling the plate around a tube.

Results: Midline adhesions (D-line) were found in all 72 patients. Mean length of D-line was 5.13 ± O.17 mm. Mean plate width before dissolution was 5.9 ± 0.15 mm, and after dissolution 7.8 ± 0.16 mm. A blind channel of type A was detected in 22 patients (31%), type B in 24 (33%), type A and B in 16 (22%), and none in 10 patients (14%). Mean final plate width after D-line dissolution and opening of septs between channels in 62 patients with urethral plate tubularization was 8.7 ± 0.15 mm.

Discussion: The main contribution of our study is a new perspective of distal urethral plate anatomy that enables enlargement of the epithelized surface of the distal urethral plate by dissolution of the preexisting epithelized groove and opening of epithelized channels within the plate. To the best of our knowledge, this anatomical anomaly has not been described previously.

Conclusions: The distal urethral plate of all hypospadias patients is partially "folded" in the midline by epithelial adhesions of different depth and extent that may be easily dissoluted. In half of the patients (53%) the "folded" part of the plate continues proximally as a blind channel inside the urethral plate (type A channel). Opening of these structures together with the well-known urethral plate pits (type B channel) helps augment the width and the overall epithelized surface of the distal urethral plate.

Keywords: Adhesions; Anatomy; Hypospadias; Urethral plate.