Distal extension of the midline urethral-plate incision in the Snodgrass hypospadias repair: An objective assessment of the functional and cosmetic outcomes

Abstract

Objectives: To objectively assess the functional and cosmetic outcomes of a modified tubularised incised-plate (TIP) urethroplasty (Snodgrass) technique, with particular attention to the uroflowmetry study and Hypospadias Objective Scoring Evaluation (HOSE) score.

Patients and methods: In a prospective case-series study, 43 consecutive patients with primary distal hypospadias were evaluated. The modified Snodgrass technique included an extension of the midline relaxing incision of the urethral plate from within the hypospadiac meatus to the very tip of the glans. The neourethra was tubularised starting at the neomeatus and proceeding proximally. The neourethra was covered with either a single or double dartos flap. In toilet-trained boys, at least 3 months after surgery, the flow pattern, maximum (Q max), and mean urinary flow rate (Q ave) were recorded, and the results plotted against a recently published flow-rate nomogram from normal children. The postvoid residual urine volume was measured using ultrasonography. The cosmetic outcome was assessed using the HOSE system.

Results: The native meatus was coronal in 11 (26%), subcoronal in 23 (53%) and distal penile in nine (21%) of the patients. The median (range) age was 4.2 (0.5-14) years. The neourethra was covered by a single dorsal dartos flap in 25 and a double dartos flap in 18 patients. At a median (range) follow-up of 6 (3-24) months, the uroflowmetry findings in 26 uncomplicated toilet-trained boys with a median (range) age of 5.2 (3.3-14) years showed an abnormal Q max below the fifth percentile in four (15%), with the Q ave above the fifth percentile in all. The flow pattern was bell-shaped in nine boys (35%), interrupted/intermittent in five (19%), slightly flattened in 10 (39%) and a plateau in two (8%). A vertical slit-like meatus located at the distal glans was created in 39 (91%) boys, and at the proximal glans in four (9%). The urinary stream was single and straight in 39 and angled in four patients. A straight erection was observed in 42 (98%) boys. Four patients had preoperative mild penile torsion of <45°, that was corrected by surgery. The mean (SD, range) HOSE score was 15.8 (0.6, 13-16). Two patients had a small, single subcoronal fistula.

Conclusion: Extending the midline urethral plate-incision in the modified Snodgrass repair to the apical part of the glans can be done safely with a high rate of locating the neomeatus at the glans tip, with no resultant meatal stenosis. The functional and cosmetic results of the procedure are good, but long-term data and comparative studies are required to confirm these results.

Keywords: HOSE, Hypospadias Objective Scoring Evaluation; Hypospadias; Outcome; Qave, mean urinary flow rate; Qmax, maximum urinary flow rate; TIP, tubularised incised-plate; Tubularised incised plate; UCF, urethrocutaneous fistula.

Figure 1

Coronal hypospadias with a urethral plate 8 mm wide (A and B). The deep midline urethral-plate incision (C). The construction of the neomeatus preceded tubularisation (D). The neourethral tubularisation is completed (E).

Figure 2

Harvesting of the dorsal dartos flap, which can be button-holed for single-layer coverage (B) or divided vertically for two-layer coverage (C–E).

Figure 3

The construction of a wide neomeatus at the tip of the glans; ventral view (A), top view (B). The intra-operative cosmetic outcome (C). The cosmetic outcome at 3 months after surgery, with a vertical slit-like meatus at the tip of a normal conical symmetrical glans.

Figure 4

(A) The Q_max plotted against the voided volume in 26 boys; four were below the fifth percentile, according to the nomogram . (B) The Q_ave plotted against the voided volume, with no patients having values below the fifth percentile.

Figure 5

The postoperative uroflow patterns. (A) A bell-shaped curve with a normal Q_max. (B) A flat curve with a normal Q_max. (C) An almost bell-shaped curve with an obstructed Q_max but normal Q_ave. (D) A plateau curve with an obstructed Q_max and normal Q_ave, and a prolonged voiding time. (E) An intermittent curve with a Q_max at the fifth and Q_ave at the 10th percentile.