Hypospadias (hi-poe-SPAY-dee-us) is a condition in which the opening of the urethra is on the underside of the penis, instead of at the tip. The urethra is the tube through which urine drains from your bladder and exits your body.
You may feel distressed if your son is born with hypospadias. However, hypospadias is common and doesn’t cause difficulty in caring for your infant. In fact, surgery usually restores the normal appearance of your child’s penis. With successful treatment of hypospadias, most males can eventually have normal adult sexual function.
Embryology of the Male Urethra:
The urethra emerges from the urethral folds, which fuse ventrally under the influence of androgens. The fusion begins proximally in the 11th week of gestation and proceeds distally. The fusion involves endodermal and ectodermal tissue. The androgen effect is mediated by the 5α-reductase.
In hypospadias, malformations concern the endodermal and ectodermal tissue. An example of an ectodermal abnormality is the deficient ventral foreskin with a dorsal “hood”. Endodermal abnormalities include the position of the meatus, a deficient urethra distal to the meatus and chordee formation (urethral plate).
An absolute (low concentration) or relative (decreased sensitivity of the target tissue) androgen deficiency is a major cause for the development of hypospadias. Many enzyme deficiencies which cause hypospadias are known, such as 5α-reductase deficiency or defects of the androgen receptor. In 10–70% of severe proximal hypospadias, an enzyme deficiency or hormonal disease affecting the androgens can be found.
Hypospadias have a multifactorial etiology involving several known genes (polygenic disease). This can be concluded from the family history and twin studies. In addition to the known enzyme defects (see above), most genes involved in the etiology of hypospadias are still unknown.
A variety of substances with estrogenic activity contaminates the environment and is enriched through the food chain. Substances with estrogenic activity are insecticides, natural estrogens from plants and chemicals from the plastics industry. The impact on wildlife is well documented: thin egg shells in birds or penis malformations in alligators. The worldwide increase in hypospadias in humans is also attributed to these environmental factors.
Penis Curvature in Hypospadias:
The chordee (urethral plate) has previously been considered the cause for ventral penile curvature in hypospadias. This is now questioned by many studies. Penile curvature is now considered a part of normal penile development. In addition, the conservation and utilization of the urethral plate is essential for hypospadia operations popularized by Snodgrass. In the majority of cases, the curvature of the penis can be corrected using the technique of Nesbit.
Hypospadias is a congenital defect that is thought to occur embryologically during urethral development, between 8 and 20 weeks’ gestation. The external genital structures are identical in males and females until 8 weeks’ gestation; the genitals develop a masculine phenotype in males primarily under the influence of testosterone. As the phallus grows, the open urethral groove extends from its base to the level of the corona.
The classic theory is that the urethral folds coalesce in the midline from base to tip, forming a tubularized penile urethra and median scrotal raphe. This accounts for the posterior and middle urethra. The anterior or glanular urethra is thought to develop in a proximal direction, with an ectodermal core forming at the tip of the glans penis, which canalizes to join with the more proximal urethra at the level of the corona. The higher incidence of subcoronal hypospadias supports the vulnerable final step in this theory of development.
In 2000, Baskin proposed a modification of this theory in which the urethral folds fuse to form a seam of epithelium, which is then transformed into mesenchyme and subsequently canalizes by apoptosis or programmed cell resorption.Similarly, this seam theoretically also develops at the glanular level, and the endoderm differentiates to ectoderm with subsequent canalization by apoptosis.
The prepuce normally forms as a ridge of skin from the corona that grows circumferentially, fusing with the glans. Failure of fusion of the urethral folds in hypospadias impedes this process, and a dorsal hooded prepuce results. On rare occasions, a glanular cleft with intact prepuce may occur, which is termed the megameatus intact prepuce (MIP) variant.
Chordee (ventral curvature of the penis) is often associated with hypospadias, especially more severe forms. This is thought to result from a growth disparity between the normal dorsal tissue of the corporal bodies and the attenuated ventral urethra and associated tissues. Rarely, the abortive spongiosal tissue and fascia distal to the urethral meatus forms a tethering fibrous band that contributes to the chordee.
In hypospadias, the opening of the urethra is located on the underside of the penis instead of at the tip. The severity of the condition varies. In most cases, the opening of the urethra is near the head of the penis. Less often, the opening is at midshaft or at the base of the penis. Rarely, the opening is in or beneath the scrotum.
Signs and symptoms of hypospadias may include:
- Opening of the urethra at a location other than the tip of the penis
- Downward curve of the penis (chordee)
- Hooded appearance of the penis because only the top half of the penis is covered by foreskin
- Abnormal spraying during urination
This problem is almost always diagnosed soon after birth during a physical exam. Imaging tests may be done to look for other congenital defects.
Treatment involves surgery to reposition the urethral opening and, if necessary, straighten the shaft of the penis.
What happens during surgery
During surgery, a pediatric urology surgeon uses tissue grafts from the foreskin or from the inside of the mouth to reconstruct the urinary channel in the proper position, correcting the hypospadias. The surgery usually takes from one to three hours and is done while the child is unconscious (general anesthesia). Rarely, the repair may require two or more surgeries.
When surgery is performed
Surgery is best done at an early age — usually between ages 3 months and 18 months. Generally, the earlier the surgery is done, the less traumatic it is for the child. But the procedure can be completed at any age and even into adulthood. Infants should not be circumcised before the procedure because the foreskin tissue may be needed for the surgery.
Complications of surgery
In most cases, surgical repair results in a penis with normal or near-normal function and appearance and no future problems. However, in a small number of cases, a hole (fistula) or scarring may develop along the underside of the penis where the new urinary channel was created. This can result in urine leakage and require an additional surgery for repair.