Colorectal Quiz: Episode 41 - Perineal Hypospadias

Prenatal diagnosis of hypospadias has become part of routine prenatal care, whereas 5-7 years ago pediatric surgeons were never called for such counseling.

The combination of urologic defects (bladder atrophy, penoscrotal transposition, severe hypospadias) and anatomic changes in the pelvic region is commonly associated with perineal fistula.

In a newborn with severe hypospadias, penoscrotal transposition, and unclear connection between rectum and urinary tract, diverting colostomy is safer than primary repair.

Colostomy makes the subsequent rectal dissection easier.

Laparoscopic colostomy with three trocars allows precise selection of the sigmoid point, external meconium evacuation, and creation of two separate stomas with no skin opening between them, which facilitates ostomy bag attachment.

Irrigating the distal colostomy segment by passing a large Foley catheter under laparoscopic view allows confirmation of meconium removal and visualization of distal segment decompression.

In this case, the distance from the perineal fistula opening to the rectal lumen was 2.5 cm, and the urethral length was almost 3 cm.

A healthy, normally developed sacrum is not surprising in a patient with a perineal fistula, given that the rectum is so low.

Five months of age is quite early for urologists to perform hypospadias repair, but waiting one year to repair the rectum is too long from the colorectal surgeon's perspective.

In most male perineal fistulas, the fistula is within the anteriormost portion of the sphincteric ellipse, allowing posterior rectal wall mobilization only with no anterior dissection and no possibility of urethral injury.

The perineal fistula opening can be located anywhere along the anterior midline raphe from within the sphincter up to the base of the scrotum, center of the scrotum, or even at the exit of the hypospadias.

In this case with a long anterior fistula, the surgical approach is to leave the 3 cm long, 1 mm diameter fistula undissected close to the urethra, work on the bulging rectal lumen posteriorly, and avoid dissecting the fistula from the perineal opening because there is essentially no wall between the urethra, the spongiosis, and the fistula.

The surgical goal is to achieve enough rectal mobilization that the anastomosis is not under tension, but less dissection is better because significant damage can occur with anterior dissection.

This repair is essentially a glorified cutback with no need to dissect the anterior rectal wall; only the posterior rectal wall needs mobilization to fill the space.

Dr. Levitt's approach is to mobilize just the lip of anterior rectal wall, leave the fistula floating as it attaches adjacent to the urethra, and let the urologist address it during future urethral dissection.

The fistula tissue is mucosally lined and might potentially be used by the urologist for hypospadias repair.

The pediatric surgeon managing the rectum does not need to chase the fistula, but the anterior rectal wall must be adequately dissected so it is completely separated, creating a healthy anterior edge of the anoplasty with no tension to prevent retraction.

In a typical newborn perineal fistula, if the rectum is right below the surface, the surgeon can complete the anoplasty with no incision anterior or posterior to it, avoiding a posterior sagittal incision entirely.

This rare perineal fistula case will need a posterior sagittal incision probably fairly close to the level of the coccyx to achieve full rectal mobilization.

Dr. Levitt would use the same approach (leaving a long fistula undissected) in perineal fistulas without hypospadias when the meconium opening is at the base of the scrotum or in the middle of the scrotum; the long narrow fistula will disappear on its own.

If transitional tissue from a perineal fistula is sent to pathology, pathologists may report no ganglia, causing panic and confusion, especially in bulbar perineal fistula patients who are likely constipated, leading to a wrong decision pathway.

Dr. Midrio's plan is to have the urologist perform at least the first-stage hypospadias repair with the colostomy still in place, between 6 to 9 months of age (a compromise between the urologist's preference for 1 year and the colorectal surgeon's preference for 6 months), then close the colostomy, and complete the hypospadias repair 6 months later.