Prenatal imaging for hypospadias: a bayesian analysis-based systematic review of diagnostic accuracy and key imaging...

The antenatal diagnosis of hypospadias has implications for parental counselling, decision-making and organizing postnatal management. Recent imaging advancements have enabled antenatal detection of hypospadias with significant implications for parental psychology and clinical management. However, there is considerable variability in the application of the diagnostic techniques and their reliability or diagnostic accuracy.

To assess the diagnostic accuracy of prenatal imaging modalities in the antenatal detection of hypospadias using a Bayesian statistical framework and to identify key imaging features that enhance prenatal diagnosis.

Comprehensive searches across PubMed, Scopus and Google Scholar identified primary research on antenatal hypospadias diagnosis, which was subject to systematic review as per PRISMA guidelines. A Bayesian model employing non-informative priors (Beta (1,1)) was used to calculate pooled sensitivity and specificity, along with corresponding 95% credible intervals, enabling the probabilistic quantification of diagnostic uncertainty.

The review included 34 studies published between 1989 and 2023, representing 280 pregnant females with 282 foetuses. Bayesian analysis revealed high sensitivity (0.87; 95% CrI: 0.80-0.92) and moderate specificity (0.46; 95% CrI: 0.34-0.58), translating into reliable detection of cases, though with a higher risk of false positives. While 2D sonography served as the universal screening tool (100%), supplementary techniques included 3D sonography (32.3%), color Doppler (32.3%) and magnetic resonance imaging (8.8%). Diagnosis occurred at a mean gestational age of 26.3 ± 5.5 weeks (range 20-39 weeks). Key imaging features identified were ventral curvature (n = 62), a shortened penile shaft (n = 52), a blunt penile tip (n = 60), Meizner's tulip sign (n = 51) and a bifid scrotum (n = 20). The tulip sign, bifid scrotum and cranially-directed phallus were exclusively associated with proximal variants.

While 2D-ultrasonography remains the primary investigative modality, antenatal detection of hypospadias may be improved through the integration of 3D ultrasound, Doppler and MRI, particularly in complex cases. Confirmatory postnatal evaluation is crucial to address the moderate specificity and risk of false-positive results. However, there is a need to address the disparities in access to advanced imaging and technical expertise in prenatal diagnosis.