Colorectal Quiz: Episode 40

About 60% of anorectal malformation patients in Chris Westgarth-Taylor's region were discharged home without the malformation being identified.

Anorectal malformation occurs more commonly in females and has a prevalence of about one in 5,000 births.

When laparoscopy reveals a blind-ending colon with no distal segment visible, an end colostomy is preferable to a divided colostomy to avoid interfering with blood supply to the distal rectum.

The only potential benefit of a divided colostomy when a blind-ending colon is seen is protecting the ultimate rectal repair, but this risks the blood supply to the distal rectum.

Meyer-Rokitansky-Küster-Hauser syndrome can occur with an anorectal malformation, though it is extremely rare.

The more common scenario is a recto-vestibular fistula with a completely normal urethra but no vagina in between (distal vaginal atresia), where the rectum ends as a fistula in the vestibule.

In this case, the rectum ends blind and quite high in the pelvis, unreachable through a posterior sagittal incision.

The sacrum appears foreshortened on imaging, suggesting caudal regression where everything below a certain level forgot to develop.

CT angiogram revealed the aorta bifurcating quite distal to the usual location, coming down to the base of the bladder and wrapping around it.

The team determined there were no large vessels going into the pelvis, so dissection could safely proceed anterior to the aorta.

The second operation was performed open with meticulous dissection anterior to the aorta and posterior to the bladder, with a limited PSARP in the supine position and anal pediasty without diversion.

Not diverting was considered safe because there was a colocolonic anastomosis at the colostomy closure site and only an analplasty with a couple of posterior sutures, unlike Hirschsprung's disease where distal obstruction from non-relaxing sphincters could blow out the anastomosis.

The limited posterior sagittal incision deliberately did not develop an incision within the perineal body to avoid destroying or scarring it for future incorporation of gynecological structures.

In the past, vaginal replacement would have been done at the same time as rectal repair, but time and research have shown that colonic neovaginas are not great for patients 20 years down the road and should be avoided.

In most cloacas, the native vagina should be able to reach and vaginal replacement should be avoided.

The introitus in this case is potentially dilatable in the future to create a functional vagina.

A buccal graft could be laid into the opened introitus area as an alternative to dilation.

Tissue engineering options for vaginal reconstruction are expected to be available within 20 years or perhaps even shorter, with researchers currently growing vaginal cells.

One can completely avoid vaginal replacement in these cases in the current era.

Gynecologist Alison May proposed providing a neovagina as a temporary bridge so the patient can menstruate, with potential removal 20 years later when tissue engineering becomes available.

If a neovagina functions well and causes no problems, there is no reason to remove it later even if it is bowel or another graft material.

Using the remaining colon in this patient for vaginal replacement would be very risky due to compromised blood supply from the prior divided stoma.

Vascular anomalies associated with anorectal malformations have not been much written about in the literature.

Mark Levitt recalls a case with an aberrant external iliac artery that looped up within the abdominal wall, resembling the obliterated umbilical artery but actually supplying blood to an extremity.

If a surgeon is uncertain about vascular anatomy during an operation, they should stop, gather more information, and reconfront the situation rather than proceeding blindly.

Fred Reichman used to say that surgeons are judged by what they are willing to stop for.

The odds of continence for this child are concerning given the anatomy.

The sphincter complex responded very well to stimulation, which is a positive finding.

The patient is not leaking urine all the time, which is a positive finding for future continence.