Hirschsprung Disease Part II with Dr. Marc Levitt

The vast majority of Hirschsprung patients do extremely well post-pull-through with normal emptying and bowel control.

Post-pull-through problem patients divide into two types: obstruction (failure to empty) and soiling.

Enterocolitis after a well-done pull-through is common in babies because they have very tight sphincters and can keep them tight for many hours.

After about age one, patients should learn to empty and relax their sphincters; enterocolitis after age one needs evaluation.

Evaluation of recurrent enterocolitis involves a contrast study of the colon and an examination under anesthesia.

Anatomic causes of post-pull-through obstruction include distal stricture, obstructing Soave cuff, atonic Duhamel pouch, twisted pull-through (up to 360°), and dilated distal segment.

An obstructing Soave cuff is aganglionic outer rectal wall that can cause obstruction if not properly split or if it has fused or scarred.

Pathologic cause of obstruction is pull-through to transition-zone bowel without healthy ganglion cells or with nerve roots larger than 40 microns.

Acute enterocolitis treatment: IV hydration, IV metronidazole (most effective antibiotic), and aggressive rectal irrigations 2–3 times daily with 10–20 cc/kg saline via size 20–22 Foley catheter.

If irrigations fail to relieve distention and improve the baby, the tube may not be reaching high enough or the patient may need an ileostomy.

Metronidazole (Flagyl) has the same efficacy IV or PO because in both cases it is excreted in the bile.

In a diverted colon with ileostomy, oral or IV Flagyl will not work for colitis because the drug exits via the ileostomy; vancomycin enemas are needed.

Literature reports 15–20% of patients have an episode of enterocolitis within the first year after pull-through.

On contrast study, look for cuff indentation in the presacral space; the pull-through should hug the sacrum, and anterior deviation suggests a space-occupying cuff.

An obstructing Soave cuff can be felt on digital rectal exam under anesthesia as a rubbery thick rubber-band structure in the sacral hollow, outside the pull-through.

Gastroenterologists used to intraluminal scope visualization may miss an obstructing cuff because it is outside the pull-through lumen.

Full-thickness biopsy should be taken 1 cm above the dentate line and sent for permanent section to assess ganglion cell quality and nerve size; frozen section is not reliable for this critical redo diagnosis.

Transition-zone bowel (ganglion cells present but hypertrophic nerves >40 microns) that is not functioning well requires redo pull-through.

Redo pull-through for transition zone: transanal dissection preserving anal canal and dentate line, plus laparotomy or laparoscopy to mobilize to healthy ganglionated bowel, often requiring removal of retained sigmoid curve.

For redo transanal dissection, hug the bowel to find the Swenson plane outside the original pull-through and outside the retained aganglionic cuff, which is an areolar space that has never been operated on.

To remove an obstructing Soave cuff: dissect pull-through from cuff, then dissect cuff from Swenson plane, and excise the cuff posteriorly and laterally to break the ring—complete circumferential removal is unnecessary.

Avoid aggressive anterior cuff dissection near the urethra and vagina; breaking the ring posterolaterally solves the obstruction.

Myectomies that have been traditionally successful may have inadvertently cut the Soave cuff rather than the internal sphincter.

Myectomy technique varies widely among surgeons; it is not standardized and can injure skeletal muscle, causing incontinence.

Post-pull-through sphincter problems are relatively rare compared to anatomic causes like cuff, stricture, or transition-zone bowel.

If all anatomic and pathologic causes are ruled out and the child still behaves obstructed, the sphincter must be the cause; this can be confirmed with anorectal manometry showing failure to relax.

Sphincter achalasia (tight sphincter with failure to relax) is relatively rare after age one; most children learn sphincter coordination over time.

Botox injection acts as a temporary myectomy and is preferred over permanent myectomy because it wears off as the child learns sphincter relaxation; a series of Botox injections is safer than permanent myectomy, which can cause incontinence.

Coordinate Botox with laxatives: inject Botox, then at 4–8 weeks (as Botox wears off) start aggressive laxatives so the child learns appropriate bowel movement pattern with reduced sphincter tone.

Botox may temporarily improve cuff obstruction if it migrates to the cuff level, but the patient will recur because the cuff must be surgically removed for long-term fix.

Anorectal manometry can measure the length of high-tone zone: 1 cm of high tone is sphincter achalasia; 3–4 cm is sphincter plus obstructing cuff.

Twisted pull-through: dissect in Swenson plane around pull-through to peritoneal reflection, then laparotomy (preferred over laparoscopy due to adhesions) to mobilize left colon, preserve sigmoid arcade, deliver bowel into abdomen, untwist, and re-pull-through.

Redo of failed Duhamel pouch is the hardest Hirschsprung redo due to pelvic fibrosis from the stapled anastomosis.

Duhamel redo technique: transanal dissection to separate pull-through from original rectum, then open abdominal approach with St. Mark's retractor for deep pelvic dissection, remove entire pouch, and convert to Swenson pull-through.

All Hirschsprung patients should be able to empty spontaneously and be clean; the concept that they will eventually get better as teenagers is wrong.

Hirschsprung patients are born with a normal anal canal and normal sphincters; if anything, their sphincters are too good (too tight).

No Hirschsprung patient is born with a missing anal canal or weak sphincter; soiling due to these defects is iatrogenic from surgery.

Iatrogenic incontinence occurs when the surgeon starts transanal dissection too low and invades the dentate line, or overstretches the sphincter during dissection.

Laparoscopy-assisted pull-through avoids deep transanal work and reduces risk of sphincter overstretching compared to aggressive transanal dissection.

Soiling patient evaluation: determine original operation type (Soave, Duhamel, Swenson), assess sphincter patency (visual, digital, manometry), and assess dentate-line integrity during EUA.

Perform digital rectal exam as the patient goes to sleep (before full muscle relaxation) to assess sphincter squeeze; many soiling patients cannot squeeze.

Contrast study in soiling patients: narrow non-dilated pull-through suggests hypermotility; dilated pull-through suggests hypomotility.

Four soiling scenarios: (1) Good sphincter/anal canal + narrow colon = hypermotile, treat with loperamide, constipating diet, fiber; (2) Good sphincter/anal canal + dilated colon = hypomotile, treat with laxatives (bridge enemas until medical regimen works); (3) Lost sphincter/anal canal + narrow colon = hypermotile without continence capacity, treat with small-volume enema plus hypermotility agents; (4) Lost sphincter/anal canal + dilated colon = no continence capacity, treat with larger-volume enema.

Hirschsprung soiling differs from anorectal malformation incontinence: Hirschsprung patients were born with good anatomy, so incontinence must be iatrogenic from surgery.

Patients with intact sphincter and anal canal have capacity for bowel control and should achieve normal continence with appropriate medical management (laxatives or constipating agents).

Capacity for bowel control is determined by intact sphincters and anal canal; if these are destroyed, the patient may not have the ability for voluntary bowel control.

Patients without capacity for bowel control (destroyed sphincter/anal canal) may need Malone appendicostomy or cecostomy for antegrade enema administration.

With methodical evaluation (contrast enema and examination under anesthesia), there is no problematic Hirschsprung patient that cannot be figured out and improved.