Hirschsprung
Maternal magnesium sulfate or other tocolytic medications can cause significant ileus in the newborn that mimics Hirschsprung's disease.
Hypothyroidism and opiate exposure (maternal addiction or overdose transmitted to baby) can present with abdominal distension and delayed meconium passage mimicking Hirschsprung's disease.
Milk protein allergy in a fed baby can mimic Hirschsprung's disease on x-ray, and irrigations help even when it is not Hirschsprung's.
Ten percent of patients with meconium plug have Hirschsprung's disease, so suction rectal biopsy should be performed even after successful plug passage.
After meconium plug passage, the contrast study should be repeated because the initial study with plug present will show dilated rectosigmoid, but the repeat study will reveal the transition zone more clearly.
In total colonic Hirschsprung's disease, there is often no obvious transition zone on contrast study.
Suction rectal biopsy is the gold standard for diagnosing Hirschsprung's disease, and some centers proceed directly to biopsy without contrast study.
Contrast study serves as a surgical GPS map of the colon anatomy and is preferred before operating, even though biopsy alone can rule out Hirschsprung's.
Expert opinionMarc Levitt4:00
The physiologic obstruction in Hirschsprung's disease leads to stasis, bacterial overgrowth, and bacterial translocation because mucosal integrity is abnormal.
A constipated baby without Hirschsprung's disease will not develop enterocolitis because their mucosal integrity and IgA levels are normal.
Down syndrome patients with Hirschsprung's disease have worse enterocolitis because they have a weaker immune barrier.
Irrigation protocol: use a 20 French soft silicone Foley catheter with warm saline in 10-20cc aliquots, washing the inside of the colon by injecting, allowing drip-back, advancing the catheter a few centimeters, and repeating for up to 30 minutes.
Irrigations should be performed two to three times per day and require a written protocol so nurses know exactly what is expected.
If irrigations are performed correctly but do not reach the transition zone, the baby will remain distended and irrigations will not be effective.
When irrigations fail despite correct technique, the surgeon must decide between a leveling colostomy (bringing dilated bowel to surface, ideally with frozen section confirmation) or an ileostomy with colonic biopsies.
Ileostomy does not require intraoperative pathology at 3 AM, the baby will thrive, and full colonic pathology data can be obtained later, but it requires three operations instead of two.
In regions where ileostomy management is difficult and babies can dehydrate quickly, ileostomy may not be appropriate.
A leveling colostomy is usually accurate when placed in dilated bowel to the surgeon's eye, but the risk is opening a colostomy still in the transition zone.
A loop ileostomy where both limbs are equal is inappropriate because stool will jump across and fill the aganglionic segment, causing continued distension and potential enterocolitis despite diversion.
A Turnbull ileostomy (cutting the bowel completely on one side of the loop, intussuscepting it over a finger to create an end-stoma appearance with flat distal opening) or a divided ileostomy with proximal end brought up and distal limb tacked to it are both appropriate diversion techniques.
Post-pull-through patients present with two distinct problems: obstruction (chronic distension, enterocolitis episodes, failure to thrive) or soiling (no distension, no enterocolitis, uncontrolled stooling).
Anatomic causes of post-pull-through obstruction include inadequate Soave cuff (not cut enough, rolled up, or refused), twisted pull-through (180 or 360 degrees), Duhamel spur (two lumens not successfully joined), large Duhamel pouch reaching into pelvis, stricture, and transition zone pull-through.
A Soave cuff feels like a rubbery circumferential ring outside the pull-through on digital exam.
A twisted pull-through prevents the examining finger from entering the pelvis; on abdominal palpation you feel like you are hitting a wall.
Contrast study may show a cuff by revealing extra presacral space on lateral view; the pull-through should hug the sacrum, and a cuff pushes it forward.
In Duhamel patients, biopsy must be taken from the posterior wall because the anterior wall is the original aganglionic rectum.
If anatomic causes and pathology are normal in an obstructed post-pull-through patient, the problem is non-relaxing sphincters, and empiric Botox is appropriate.
Every child born with Hirschsprung's disease has 100% potential for bowel control because the continence mechanism is normal and the sphincters are strong, not weak.
This is very different from anorectal malformation, where associated spinal problems, poor sacrum, or poor muscles can prevent continence despite a perfect operation.
Overstretching of sphincters or starting transanal dissection too low (removing the dentate line) will cause iatrogenic fecal incontinence.