Colorectal Quiz: Episode 46 - Hirschsprung's Disease

Trisomy 21 is associated with approximately 50 times higher incidence of Hirschsprung disease than in non-trisomy 21 patients, with about 5-10% of trisomy 21 patients having Hirschsprung disease.

Rectal irrigations for Hirschsprung enterocolitis should use 20 mL per kg, 3 times a day.

In Hirschsprung disease with free air, perforation typically occurs in the cecum when the transition zone is around the hepatic flexure, because the right colon becomes very dilated with nowhere to empty and the cecum perforates according to Laplace's law.

In anorectal malformation patients with delayed diagnosis, perforation typically occurs in the sigmoid colon as a linear longitudinal tear along the taenia.

When a baby is taken to OR with free air and a perforation is found in the cecum, this should prompt rectal biopsy for Hirschsprung disease, and most such patients would get an ileostomy with the transition zone likely at the hepatic flexure.

The physiologic obstruction in Hirschsprung disease occurs both at the sphincter level and in the aganglionic segment; breaking this cycle requires getting a tube across it to allow egress of stool, as stasis leads to bacterial overgrowth and translocation causing sepsis.

Irrigation technique involves instilling small aliquots of warm saline (20-40 mL at a time) and withdrawing it with the catheter to evacuate the saline, not just infusing it into the colon lumen, continuing until output is clear.

Hirschsprung disease is almost never an emergency operation; irrigation usually wins the day.

Contrast enema findings in Hirschsprung disease include rectosigmoid ratio less than 1, saw-toothing in the rectum indicating hyperperistalsis, and signs of enterocolitis visible in the left colon.

Definitive diagnosis of Hirschsprung disease requires absence of ganglion cells on 100 levels and presence of hypertrophic nerves greater than 40 microns.

Frozen section can only definitively rule out Hirschsprung disease (by showing ganglion cells) but cannot definitively confirm it, because confirmation requires 100 levels showing no ganglion cells anywhere, which frozen section cannot provide.

Calretinin staining is used as an additional confirmatory test: if calretinin is present, it means ganglion cells are nearby; if calretinin is absent, it further confirms Hirschsprung disease.

For patients recovering from Hirschsprung enterocolitis who can be fed and have successful irrigations, experts recommend waiting minimum 4 weeks (possibly up to 3 months) before definitive surgery, with literature from PCPLC showing similar outcomes with delayed treatment.

If a patient with Hirschsprung disease is clinically improved with irrigations but cannot be fed, diversion is a reasonable next step rather than continuing to wait.

For mapping biopsies, the recommended approach is to go directly to the sigmoid (the 'money' location) rather than doing unnecessary biopsies; if frozen section shows ganglion cells in the sigmoid, no other biopsies are needed.

If mapping the colon without frozen section available, biopsies should be taken from left colon, transverse colon, and hepatic flexure/right colon, because once past the hepatic flexure into distal ascending colon, pull-through becomes technically difficult.

The appendix should not be biopsied for Hirschsprung mapping because many patients' appendixes are aganglionic, and the appendix should be saved for possible future use.

When going to OR electively for pull-through and finding no ganglion cells in sigmoid or left colon, the surgeon should not proceed with pull-through that day; instead, biopsy transverse colon and hepatic flexure, do an ileostomy with frozen section confirmation, and return another day once permanent sections confirm the transition zone.

Frozen section interpretation should be done cautiously in the setting of active enterocolitis because inflammation can obscure ganglion cells and make the frozen section unreliable for decision-making.

In resource-limited settings without frozen section availability or quick access to medical care for dehydration management, bringing up a colostomy in the dilated portion is preferred over ileostomy because ileostomy patients can become dehydrated and may not have quick enough access to care.

Modern technology allows pathology support for resource-limited settings: surgeons can perform segmental biopsies, do H&E stains, and send microscope images via Zoom to expert pathologists who can evaluate for ganglion cells, potentially saving 80% of colons in rectosigmoid Hirschsprung disease.

In settings with frozen section availability and ability to manage hydration, ileostomy is preferred over leveling colostomy because colostomy mesentery becomes shortened and inflamed after division, making subsequent pull-through technically difficult with the colon sometimes not reaching.

When performing ileostomy for Hirschsprung disease, frozen section should be done on the ileostomy site to make absolutely certain it will function.

Even with elegant surgical technique that preserves the anal canal and avoids sphincter overstretch, Hirschsprung patients will still get some enterocolitis because the surgery preserves the continence mechanism, which by definition means they cannot relax their internal sphincter and therefore remain susceptible to enterocolitis.

Patients who had Hirschsprung surgery with overstretched sphincters never got enterocolitis but developed fecal incontinence requiring bowel management programs.

A published negative study showed that Botox injection at one month post-pull-through did not help prevent enterocolitis.

Cincinnati Children's Hospital is conducting a prospective study of Botox injection at the anal sphincter at the time of restoring intestinal continuity for enterocolitis prevention, with mid-thirties patient enrollment, though some patients in the protocol have still developed enterocolitis and increased diaper rash has been observed.

Families should be sent home with equipment to irrigate and taught how to irrigate before the pull-through so they can practice, avoiding the need for catheter passage through the anastomosis on post-op day 5 when ready for discharge.