Hirschsprung’s disease

What is Hirschsprung’s disease?

Hirschsprung’s disease is characterised by an absence of ganglion cells in the distal bowel, beginning at the internal sphincter and extending proximally. The resulting aganglionic segment of the colon fails to relax, causing a functional obstruction. Presentation is commonly in the first 28 days of life (neonatal period), with delayed passage of meconium and abdominal distension (see “Red flags” box). However, about 12% of patients present again in childhood with intractable constipation (not responsive to laxatives) and failure to thrive, with about a third of these presenting with enterocolitis.1 2

Why is Hirschsprung’s disease missed?

Hirschsprung’s disease mainly presents to primary care as delayed passage of meconium or as constipation.2 9 Missed or delayed diagnoses are decreasing owing to vigilance in primary care and early biopsy, with the mean age at diagnosis falling from 18 months in the 1960s to 2.6 months in the past 10 years.2 11 However, substantial numbers of children with Hirschsprung’s disease still present late (after age 3 years). Many late presentations result from missed diagnoses in primary care, but delayed presentation to primary care is sometimes a contributing factor, particularly in developing countries.9

Guidelines from the National Institute for Health and Clinical Excellence (NICE) recommend that normal passage of meconium within 24 hours of birth should be confirmed at the newborn examination (within 72 hours of birth) and that the stooling pattern should be reviewed at the six week postnatal check by the general practitioner.3 A retrospective review over five years of 429 Italian children who had had a rectal biopsy found that 47 had Hirschsprung’s disease, of whom 10 (21%) had been referred from primary care after the age of 2 years, despite persistent symptoms since the neonatal period.12 Another literature review found that 475 (97%) of 490 children with Hirschsprung’s disease who presented after the age of 10 years (a rarer subgroup) had presented with symptoms that had persisted since the neonatal period—abdominal pain, distension, and constipation refractory to laxatives.13

However, some late presentations to primary care occur. For example, a retrospective Kuwaiti review found that 14 (14%) of 102 patients with confirmed Hirschsprung’s disease were aged over 1 year at diagnosis.10 The researchers attributed some of the delayed diagnoses to home laxative treatment and neglect of initial symptoms. And the Italian review cited above noted that 5% of children in their series had symptoms that started after the age of 1 year.12

Why does it matter?

Patients who have been referred late with Hirschsprung’s disease may need more complicated corrective surgery, and older children with the disease have an increased risk of needing multiple operations and potentially a stoma, rather than the single stage pull-through operation for neonates.2

Delayed diagnosis of Hirschsprung’s disease also increases the likelihood of associated enterocolitis, which is thought to arise from innately impaired colonic mucosal barrier against pathogens, an impairment that remains after surgery.14 Patients present with shock, fever, and abdominal distension and may present as late as the age of 10 years and, less commonly, after surgical correction. Surgical correction for patients with enterocolitis associated with Hirschsprung’s disease is more likely to necessitate a stoma. The Australian Paediatric Surveillance Unit found in 2003 that, among 127 children with Hirschsprung’s disease, the incidence of associated enterocolitis was 33% (4/12 patients) in those with a late diagnosis, compared with only 12% (15/126) in those with a diagnosis in the neonatal period. The postoperative incidence of associated enterocolitis was 21% but with no deaths.2 A rate of death from enterocolitis associated with Hirschsprung’s disease of 5-25% in older series has now decreased to about 1% in more recent series.2 15 This fall has been attributed to raised awareness in primary care, and earlier diagnosis.2

Unnecessary rectal biopsies in children with functional constipation can also be avoided with an appropriate history (see below). A 1998 UK retrospective review assessed the notes of 141 patients who had had a rectal biopsy, including 17 patients with Hirschsprung’s disease. The researchers concluded that normal passage of meconium, and being symptom-free beyond the age of 1 month, obviates the need for biopsy and that 60% of rectal biopsies performed to exclude Hirschsprung’s disease would not have been indicated4; other studies, however, disagree with such a categorical statement.3 12

How is Hirschsprung’s disease diagnosed?

Investigations

Hirschsprung’s disease is diagnosed by identifying the absence of ganglion cells on rectal suction biopsy, which is generally taken about 2 cm above the dentate line of the rectum. Other investigations aim to reduce the number of referrals for rectal suction biopsies. These include anorectal manometry, barium enema, and plain abdominal radiography (figure⇓), the last of which is useful in looking for any anomalies needing surgery in neonates with delayed passage of meconium and abdominal distension, and is readily available. A prospective study of 111 consecutive patients compared the relative sensitivities and specificities of these diagnostic tests for Hirschsprung’s disease and found that anorectal manometry (83% sensitive, 93% specific) was similar to barium enema (76% sensitive, 93% specific), but rectal suction biopsy was superior (93% sensitive, 100% specific).22

Abdominal x ray image showing gaseous distension of the large bowel with air absent from the rectum (typical of Hirschsprung’s disease)

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How is Hirschsprung’s disease managed?

The length of affected bowel can be variable, occasionally involving the whole colon, but generally restricted to the rectum and sigmoid.8 Further management includes stabilisation (through resuscitation, antibiotics if indicated, and decompression, with a nasogastric tube and rectal washouts). This is followed by surgery, which allows identification and resection of the aganglionic section and, where possible, allows the normal ganglionic bowel to be brought down to be anastomosed to the anus in a single stage procedure while preserving sphincter function.8

Post-surgical morbidity has lessened with time. A case series in 2008 following 192 patients postoperatively showed no perioperative deaths but anastomotic leakage in four patients. At follow-up (at 6-40 months), of 145 patients, 7 had faecal incontinence, 8 had constipation, and 38 (26%) had had enterocolitis.23 Enterocolitis is mainly managed conservatively, with intravenous fluids, bowel rest, and antibiotics.

In the long term, most patients who have had Hirschsprung’s disease enjoy an excellent quality of life, with near normal anorectal function after surgery, although some abnormalities of bowel function can persist.14 One long term follow-up study found that 75-95% of patients achieve a stool frequency of <5 stools a day.6 Parents should be advised of the increased risk of Hirschsprung’s disease for any future children they have.24