Keywords
Hirschsprung disease - chronic distension - colonic dysmotility - chronic constipation
- pull-through
Case Report
A 14-year-old boy with chronic abdominal distension, poor growth (less than 1 percentile
for weight), and chronic constipation presents to your clinic. He reports a history
of passing hard stools every 2 to 3 days without the need for laxatives or an enema.
At least once a week, he experiences fecal soiling. He has never had any episodes
of enterocolitis. On abdominal exam, he has palpable stool burden. You are suspicious
of Hirschsprung disease and obtain an awake anorectal manometry which shows an absent
rectoanal inhibitory reflex. A rectal biopsy shows no ganglion cells and hypertrophic
nerves, confirming the diagnosis of Hirschsprung disease (HD). His contrast enema
study is demonstrated in [Fig. 1].
Fig. 1 Contrast enema study.
Discussion
Late diagnosed HD (in children over the age of 2 years) presents differently than
in the newborn period and warrants a different approach for surgical planning and
management. Constipation is the number one presenting symptom in this group of patients[1] and they are more likely to have shorter segment disease with a transition zone
in the rectosigmoid, and often in the rectum itself. These patients are less likely
to present with enterocolitis, perhaps due to adaptive changes by the colon reacting
to chronic distension, including hypertrophy and dilation.[1] Or such patients might have a different mucosal immunity, making bacterial translocation
less likely.
In deciding on a surgical approach for patients with HD, the age of the patient should
be factored into the decision-making, in addition to location of transition zone,
extent of colonic dilation, as well the patient's nutritional status.[2]
[3] In the case presented, the contrast enema demonstrates a low transition zone at
the rectosigmoid junction with dilation of the sigmoid colon extending to the descending
colon. His history also suggests malnutrition and failure to thrive, not uncommon
in HD, but much rarer in functional constipation and colonic motility disorders. We
will discuss how each of these factors influence the decision to proceed in this case
with a diverting ileostomy with colonic biopsies and future pull-through.
The location of the transition zone guides whether the patient can undergo a transanal
only approach or whether laparoscopic assistance will be needed. A low transition
zone, in the midsigmoid colon or lower, is a unique opportunity for a transanal only
approach, as colonic mobilization is usually not required to create a tension-free
anastomosis.[2] However, a laparoscopic mobilization of the distal rectum and sigmoid prevents stretching
of the anal canal during the rectal dissection. Such overstretching of the sphincters
is one of the main causes of postoperative morbidity and must be avoided.[4] If the transition zone is in the proximal sigmoid or above, mobilization of lateral
and retroperitoneal attachments may be needed to ensure adequate length.[2] The contrast enema is very helpful in identifying the likely transition zone as
the surgeon plans for surgery ([Fig. 2]); however, the level must be confirmed by colonic biopsy. In this patient, a primary
pull-through would not be appropriate despite a low transition zone, given the presence
of significant colonic dilation and malnutrition.
Fig. 2 Contrast enema study with demonstration of transition zone at rectosigmoid junction.
(A) Sigmoid colon. (B) Rectosigmoid junction and transition zone.
Dilated bowel presents a significant technical challenges with visualization during
laparoscopy, which may lead to nearby structural injuries.[2] A transanal dissection has been noted to lead to excessive stretching of the anal
sphincter, which can lead to incontinence,[5] and a dilated colon anastomosed to the canal with a significant size discrepancy
is a risk factor for an anastomotic dehiscence. Malnutrition is a known risk factor
for anastomotic leak.
Intestinal diversion and decompression are recommended to address these issues. A
leveling colostomy in most clinical settings is preferred, as an ileostomy does put
the patient at risk for dehydration.[5] During enterostomy creation, colonic biopsies assessed on permanent section can
more reliably confirm the location of the transition zone compared with frozen section
analysis. While regular colonic irrigations are another option for decompressing dilated
colon, they commonly do not provide adequate decompression in older children, who
also may be less likely to tolerate regular irrigations.[5]
Conclusion
In summary, while one-stage pull-through procedures are convenient and desirable due
to reduced morbidities of stoma formation, these may be limited to children with low
transition zones and minimal to no proximal colonic dilation. In the rare circumstance
of a late-diagnosed child with HD with proximal colonic dilation and/or malnutrition,
a decompressive ostomy as a first step, and a plan for a future pull-through is a
safer option to help prevent complications such as anastomotic leak, incontinence,
obstruction, and need for a repeat pull-through. In an older child, the presentation
of HD is often more subtle, with constipation, failure to thrive, and chronic distension
being the dominant symptoms. It is rare that such patients have experienced enterocolitis.
Why this case is unclear, and points to the broad spectrum of phenotypic expression
of the disease.
