Meatal mismatch and GMS scoring: change in meatal location after degloving is associated with short-term urethrocutaneous fistula development in hypospadias repairs.
Anthony D'Oro, BA, Yvonne Y. Chan, MD, Ilina Rosoklija, MPH, Emilie K. Johnson, MD, MPH, Dennis B. Liu, MD, Edward M. Gong, MD, Max Maizels, MD, Derek J. Matoka, MD, Elizabeth B. Yerkes, MD, Bruce W. Lindgren, MD, Earl Y. Cheng, MD, David I. Chu, MD, MSCE.
Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA.
BACKGROUND: Complication rates following hypospadias repair have been shown to correlate with Glans-Meatus-Shaft (GMS) score. The "M" component of the GMS score is assessed preoperatively, but if meatal location changes after penile degloving, there can be pre- and post-degloving "meatal mismatch." We examined the association between meatal mismatch and postoperative fistula development, hypothesizing that meatal upstaging (meatus moving more proximal after degloving) would be associated with higher risk of fistula development.
METHODS: We performed a single-institution, retrospective cohort study of boys who underwent primary hypospadias repair from 2011-2018. Intraoperative details were collected prospectively. Patients with incomplete data or who avoided penile degloving were excluded. We collected preoperative, intraoperative, and postoperative data, including pre- and post-degloving meatal location (glanular, coronal, distal/midshaft, proximal). Meatal mismatch was classified as meatal upstaging (meatus moving more proximal after degloving) or meatal downstaging (meatus moving more distal). The primary outcome was urethrocutaneous fistula development. Using time from latest stage surgery, a survival analysis with multivariable Cox regression models was performed to assess the impact of meatal mismatch on fistula development.
RESULTS: Of 535 primary hypospadias patients, 485 (91%) were eligible. Median age at first surgery was 9.7 months old (interquartile range [IQR] 8.1-13.0). Median follow-up from latest stage surgery was 7.3 months (IQR 2.0-20.9). GMS meatal locations were glanular, coronal, distal/midshaft, and proximal in 8%, 23%, 50%, and 18% of patients, respectively. After degloving, 75/485 (15%) patients had meatal upstaging, while 24/485 (5%) had meatal downstaging (Figure). 70/485 (14%) of patients underwent planned multi-stage repair. After the latest stage surgery, fistulae developed in 56/485 (12%) patients at median of 6.8 months (IQR 1.8-14.6). In Cox regression analyses, base models incorporating GMS pre-degloving meatal location, chordee severity, and staged repair did not show a significant association between GMS meatal location and fistula development (Table). After adding meatal mismatch to the base model, meatal upstaging was associated with a higher risk of fistula development compared to no meatal mismatch (Hazards Ratio [HR]: 3.82, 95% Confidence Interval [CI]: 1.87-7.83; p<0.001). Additionally, proximal meatal locations were associated with fistula development, compared to glanular meatal locations (HR: 8.08, 95% CI: 1.42-46.00; p=0.02). Meatal downstaging was not associated with fistula development. Planned multi-stage, compared to single-stage, repair was associated with a lower risk of fistula development (HR: 0.25, 95% CI: 0.09-0.68; p=0.01). The likelihood ratio test comparing models was statistically significant, signifying better fit with meatal mismatch than without.
CONCLUSIONS: After short-term follow-up of hypospadias repair, meatal upstaging was associated with higher risk of fistula development, despite adjustment for other known risk factors for fistula development. Though longer-term results are needed, these results suggest that the "M" in GMS scoring system should account for meatal mismatch after penile degloving. 
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