Colorectal Quiz: Episode 46

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

In Hirschsprung disease with perforation, the cecum perforates due to Laplace's law, and this indicates the transition zone is probably around the hepatic flexure because the right colon becomes very dilated with nowhere to empty.

In anorectal malformation patients with perforation, the sigmoid colon typically perforates with a linear, longitudinal tear along the taenia.

The pathophysiology of Hirschsprung enterocolitis involves physiologic obstruction at both the sphincter level and in the aganglionic segment, leading to stasis, bacterial overgrowth, translocation, and sepsis.

Proper irrigation technique involves instilling small aliquots of warm saline (20-40 mL at a time) and actively withdrawing with a catheter to evacuate the saline, not just infusing it into the colon lumen.

Cold saline used for irrigations in small children can significantly change the child's body temperature, so warm saline should be used.

Hirschsprung disease is almost never an emergency operation, and irrigations usually win the day.

The rectosigmoid ratio less than one on contrast enema is indicative of Hirschsprung disease.

Sawtoothing in the rectum on contrast enema represents hyperperistalsis and is very classic for Hirschsprung disease, particularly when associated with enterocolitis.

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

Frozen section can only definitively tell you it is NOT Hirschsprung disease (if ganglion cells are present), but cannot definitively confirm it IS Hirschsprung disease because that requires 100 levels with no ganglion cells anywhere.

Calretinin staining is used as an adjunct: if calretinin is present, ganglion cells are nearby; if calretinin stain is absent, this further confirms Hirschsprung disease.

If a patient has recovered from enterocolitis and irrigations are going well with reliable family, it is reasonable to send them home for 1-2 months before definitive operation rather than operating at 2 weeks.

Literature from the PCPLC and Michael Rollins shows that delayed definitive surgery for Hirschsprung disease (around 3 months out) has similar outcomes, so it is okay to wait as long as patient receives good irrigations and is growing and healthy.

If a baby with Hirschsprung disease is improving with irrigations but cannot be fed, diversion is a reasonable next step to allow enteral nutrition and growth.

For leveling biopsies, the optimal strategy is to go directly to the sigmoid ('go for the money') and if frozen section shows ganglion cells, no other biopsies are necessary.

If mapping the colon without frozen section available, the entire colon should be mapped (left colon, transverse colon, and hepatic flexure/right colon) to avoid missing ganglionic segments.

The appendix should not be biopsied for Hirschsprung mapping because it is not helpful and should be saved for potential future use; many patients' appendixes are aganglionic.

Frozen section interpretation can be difficult in the setting of active enterocolitis due to excessive inflammation obscuring ganglion cells.

In resource-limited settings without frozen section availability, the strategy is to bring up the dilated portion of colon as ostomy because it is more likely to be functional.

In resource-limited settings, ileostomy is not a good option because patients cannot access medical care quickly enough if they become dehydrated, so colostomy is preferred.

Modern telemedicine technology allows pathology slides (H&E stains) to be photographed through microscope and sent via internet for remote ganglion cell evaluation, helping save colons in resource-limited settings.

By pure numbers, 80% of Hirschsprung disease cases are rectosigmoid, so remote pathology evaluation saves many colons.

In settings where patients can be kept well hydrated with easy healthcare access, ileostomy is preferred over colostomy for diversion because colostomy mesentery becomes shortened and inflamed after division, making subsequent pull-through technically difficult with inadequate reach.

When performing ileostomy for Hirschsprung diversion, frozen section should be done on the ileostomy to ensure it will function.

If a surgeon does a good job with pull-through using elegant technique, preserving the anal canal, and not overstretching sphincters, the patient will still get some enterocolitis because the continence mechanism is preserved and patients cannot relax their internal sphincter.

Patients whose sphincters were overstretched during Hirschsprung surgery developed fecal incontinence but never got enterocolitis, demonstrating the relationship between sphincter function and enterocolitis risk.

A study of Botox injection at one month post-operatively for Hirschsprung disease showed it did not help prevent enterocolitis (negative study published).

Cincinnati group is conducting a non-randomized study of Botox injection at the anal sphincter at time of ileostomy closure, with retrospective baseline comparison and prospective data collection currently in mid-30s patients; some patients in the protocol have still developed enterocolitis, so it is not 100% effective.

Families should be sent home with equipment to irrigate and taught how to irrigate before the pull-through so they can practice, ensuring they know the technique before discharge and avoiding catheter passage through fresh anastomosis post-op day 5.