AssessmentsHypospadias and epispadias
Hypospadias and epispadias
USMLE® Step 1 style questions USMLE
A 1-day-old boy is seen for his newborn examination. During genital evaluation, his foreskin does not completely encircle the glans. There appear to be two urethral openings, one at the distal tip of the glans, and one located on the ventral surface. The penis appears normal in length. Which of the following is the most appropriate diagnosis?
Content Reviewers:Rishi Desai, MD, MPH
So instead of having an opening at the tip of the urethra, hypospadias refers to an abnormal opening on the bottom of the urethra and epispadias refers to an abnormal opening on the top of the urethra, and both of these can happen in boys and girls, but are way, way more common in boys.
During genital development in the fetus, there's a point in the 8th week of gestation, when both boys and girls have a similar bit of tissue called the genital tubercle which normally grows in the cranial direction, meaning that it grows towards the head.
After that point, in boys, the genital tubercle responds to the hormone dihydrotestosterone and stretches out a bit into a primitive phallus.
As it grows in length, an area of tissue on the underside called the urethral plate invaginates to form a urethral groove which is lined with epithelial cells.
In the 14th week of gestation, the two urethral folds on the sides pinch off the groove to make it close, and form the penile urethra.
In the 17th week of gestation, the ectodermal cells of the glans penis or head of the penis also undergo a process of canalization, and the urethral canal connects with the penile canal, and that means that the urethra eventually meets the outside world at the tip of the penis.
In a boy, hypospadias happens when the urethral folds along the penile urethra don’t meet up and close properly.
And that leaves an opening somewhere along the bottom of the penile shaft and urine can leak out at that spot, instead of going out the tip of the penis like it should.
Anatomically, hypospadias can happen in three areas: glanular, which is near the head of the penis, midshaft, which is the middle of the penis, and penoscrotal—where the penis and scrotum come together.
Generally, the least severe hypospadias are glanular and most severe are penoscrotal.
Now, with regard to epispadias, the problem starts during the 6th week of gestation when the genital tubercle grows in a posterior direction, towards the rectal area instead of the cranial direction.
In a boy, this results in an opening along the upper surface of the penis.
And anatomically, epispadias can happen in three areas: penopubic, where the base of the penis and the abdominal wall come together, penile, which is just somewhere along the penis, and again glanular—near the head of the penis.
Generally, the least severe are glanular, and the most severe are penopubic.
In this case, the genital tubercle elongates only gets a little bit longer and then forms the clitoris.