Performance of ultrasound in detecting fetal hypospadias during pregnancy: a pooled analysis.

Background: Opinions regarding the role and value of ultrasound in the diagnosis of prenatal hypospadias are diverse. Although hypospadias is not a fatal malformation, a higher degree of severity exerts a significant impact on children's physiology and psychology. On the other hand, hypospadias may be accompanied by accompanying anomalies, syndromic conditions, and fetal growth restriction (FGR). This study aimed to systematically assess the value of ultrasound in the prenatal diagnosis of hypospadias.

Methods: In the systematic review and meta-analysis, we searched PubMed, Web of Science, Scopus, Embase, and China National Knowledge Infrastructure (CNKI) databases until June 30, 2024. The key terms included: hypospadias, ultrasound, and prenatal diagnosis. Studies were assessed following the eligibility criteria, and the data from the included studies were extracted through a standardized protocol. The primary outcomes focused on the positive predictive value (PPV), accuracy, sensitivity, and specificity of ultrasound for detecting fetal hypospadias. The Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) scale was used to assess the risk of bias. The PPV was calculated using the bootstrap method. When five or fewer studies were pooled, a random-effect model based on the Hartung-Knapp-Sidik-Jonkman (HKSJ) method was used as a meta-analysis strategy to evaluate the overall effect. Sensitivity and specificity were pooled using a Summary Receiver Operating Characteristic (SROC) curve. The protocol was registered with PROSPERO (CRD42024586840).

Findings: A total of nine studies with 600 cases were included in the systematic review. The pooled median gestational age of the included studies was 27.64 ± 3.15 weeks. The overall PPVs of two-dimensional ultrasound (2DUS) in diagnosing fetal hypospadias and external genital malformations were 81% (95% confidence interval (CI): 77%-85%) and 88% (95% CI: 86%-91%), respectively. Upon in-depth analysis of the five studies, the accuracy of 2DUS combined with three-dimensional ultrasound (3DUS) was 84% (95% CI: 78%-89%), and that of 2DUS alone was 74% (95% CI: 69%-78%). The difference between the two methods was 10%. The pooled sensitivity of 2DUS combined with 3DUS in diagnosing fetal hypospadias was 86% (95% CI: 79%-93%), the specificity was 77% (95% CI: 69%-86%), and the area under the curve (AUC) was 0.86 (95% CI: 0.83-0.89).

Interpretation: This is the first diagnostic meta-analysis to comprehensively evaluate the detection of fetal hypospadias using ultrasound during pregnancy, indicating that ultrasound is indeed of significant value in the prenatal diagnosis of hypospadias. More research is needed to validate and enhance current research findings and offer more comprehensive guidance for future clinical practice.

Funding: This work was supported by the Natural Science Foundation Project of Chongqing, Chongqing Science and Technology Commission (CSTB2022NSCQ-MSX1001) and the Program for Youth Innovation in Future Medicine, Chongqing Medical University (W0109).