Hypospadias is a congenital condition in male infants where the urethra, the tube that carries urine from the bladder, does not open at the tip of the penis. Instead, the opening is located somewhere on the underside of the penis, which can range from just below the tip to the scrotum or even further back. It is one of the more common birth defects found in boys.
Prenatal Ultrasound Detection of Hypospadias
It is sometimes possible but not guaranteed to see hypospadias before birth. Detection can occur during routine second-trimester anomaly scans, performed between 18 and 22 weeks of gestation. During this period, the fetal anatomy is large enough to be evaluated in detail, including the external genitalia.
Sonographers look for specific markers that may suggest hypospadias. One indicator is a penis that appears short or has a “blunt tip” appearance. Another sign is a ventral curvature, known as a chordee, where the penis is bent downward. In more severe cases, a “tulip sign” may be observed, where the penis is curved and positioned between the scrotal folds, creating an image resembling the flower.
Detecting hypospadias with ultrasound has several limitations. The position of the fetus can make it difficult to get a clear view of the genital area. Milder forms are much harder to identify than severe cases. While studies show that the positive predictive value of ultrasound for genital anomalies is high, the specific diagnosis of hypospadias is slightly lower, as some ultrasound findings can overlap with other conditions. A definitive diagnosis and assessment of severity are therefore confirmed by a physical examination after the baby is born.
Ultrasound for Associated Urogenital Anomalies
When hypospadias is suspected prenatally or confirmed after birth, medical evaluation often extends beyond the penis itself. Hypospadias can sometimes occur with other anomalies of the urogenital system, which includes the urinary tract and reproductive organs. Ultrasound serves as a non-invasive imaging tool to screen for these associated conditions.
Ultrasound is often directed at the kidneys and bladder. It can identify structural kidney abnormalities, such as one or both kidneys being absent (renal agenesis), being in an unusual location (ectopic kidney), or being swollen due to a buildup of urine (hydronephrosis). The presence of such findings can influence the infant’s overall management plan and prompt further specialized care.
In addition to the urinary tract, ultrasound can be used to locate the testes. In some infants with hypospadias, one or both testes may not have descended into the scrotum, a condition called cryptorchidism. In cases of severe hypospadias combined with undescended testes, there may be a need to evaluate for disorders of sex development. An ultrasound might be used to look for internal pelvic structures, such as Müllerian remnants, which are vestiges of female reproductive organs.
Understanding Ultrasound Findings and Next Steps
It is important to understand the limitations of the scan; it can suggest the presence of the condition but cannot precisely determine its severity or the exact location of the urethral opening.
If hypospadias is suspected before birth, the typical follow-up involves prenatal counseling. This may include conversations with a maternal-fetal medicine specialist or a pediatric urologist, who can explain the findings, discuss potential outcomes, and help plan for a thorough postnatal evaluation.
After birth, an infant with suspected or confirmed hypospadias is referred to a pediatric urologist for a comprehensive assessment. The findings from any postnatal ultrasounds, particularly those related to the kidneys or testes, are integrated into this evaluation. This allows the medical team to formulate a management plan, which often involves surgical correction to reposition the urethral opening and repair any associated chordee.