Hypospadias Embryology, Etiology, and Classification

Abstract

Under the influence of testosterone produced by the Leydig cells, male external genitalia develops from the indifferent genital tubercle, urogenital folds, and labioscrotal folds that flank the urogenital membrane. Any arrest in development may lead to varying degrees of hypospadias in which the meatus falls short of its usual location at the tip of glans, while the hypoplastic growth on the ventral surface is overwhelmed by the growth of the tissues dorsally leading to ventral curvature or chordee. Though exact etiology of hypospadias remains uncertain, it is thought to be multifactorial, with placental insufficiency, endocrine factors, genetic factors, and exposure to environmental agents such as phytoestrogens and pesticides playing a possible role. Various attempts have been made to classify hypospadias, mostly based on the location of the urethral meatus but they remain mainly anatomical and do not predict the complications. Recently, GMS (glans, meatus, shaft) scoring system has been introduced, which also predicts the complication rate but it needs further validation in larger cohorts. Etiological classification of hypospadias may be useful for severe variety as an initial tool to standardize the diagnostic approach but majority of patients with hypospadias have no identifiable etiology.