Hypospadias: Pathogenesis, diagnosis, and evaluation
- Laurence S Baskin, MD, FAAP
Laurence S Baskin, MD, FAAP
- Section Editor — Pediatric Urology
- Frank Hinman, Jr., MD, Distinguished Professorship in Pediatric Urology
- Chief Pediatric Urology
- Professor of Urology and Pediatrics
- UCSF Benioff Children's Hospital
Hypospadias is a congenital anomaly of the male urethra that results in abnormal ventral placement of the urethral opening. The location of the displaced urethral meatus may range anywhere within the glans, the shaft of penis, the scrotum, or perineum (picture 1).
The pathogenesis, diagnosis, and evaluation of hypospadias will be reviewed here. The management and outcome of hypospadias are discussed separately. (See "Hypospadias: Management and outcome".)
The external genitalia in the two sexes develop from common anlagen (genital tubercle, swellings, and fold) and are indistinguishable until seven to eight weeks gestation (figure 1).
At the seventh or eighth week of gestation, the external genitalia begin to differentiate between the two sexes due to androgenic stimulation in male fetuses:
●In the male fetus, androgenic stimulation induces the urethral groove to fuse in a proximal to distal fashion forming the tubular urethra (picture 2 and figure 2). The penile urethra forms as a result of remolding and fusion of the medial edges of the endodermal urethral folds . This involves a distal canalization of the urethral plate (opening zipper) and simultaneous fusion of the proximal urethral folds (closing zipper) (figure 2). By 12 weeks gestation, the coronal sulcus separates the glans from the shaft of the penis. By 16 to 18 weeks, urethral formation is complete, and the foreskin completely covers the glans.
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- Proposed mechanism
- - Genetic defects
- - Environmental exposures
- Risk factors
- INITIAL EVALUATION
- General physical examination
- Genital examination
- - Hypospadias classification
- Forme fruste (incomplete or partial presence) of hypospadias
- Standard hypospadias
- Severe hypospadias
- Other uncommon variants
- DIFFERENTIAL DIAGNOSIS
- FURTHER EVALUATION
- Disorders of sexual development
- - Evaluation
- Presence of other organ anomalies
- Isolated hypospadias and renal imaging
- INFORMATION FOR PATIENTS
- SUMMARY AND RECOMMENDATIONS