Hirschsprung's disease (HD) is a congenital condition of the bowel. It affects approximately one in 5,000 newborns and affects males four times as often as females. While most cases are sporadic, genetic factors can play a role. The commonest associated genetic condition is Down's syndrome (5-15 per cent).
HD usually presents in the first few days of life with delayed passage of meconium, abdominal distension and bilious vomiting. These features do not always present together hence a neonate presenting with any one should be referred urgently to a paediatric surgical centre.
At this point other surgical pathologies will also be considered, including: malrotation with volvulus, meconium ileus, intestinal atresia and imperforate anus. Delayed passage of meconium in the neonate can also be due to non-surgical causes, such as opiates, electrolyte disturbance, hypothyroidism and sepsis.
The baby may show clinical signs of shock and sepsis, and will most likely have a distended abdomen which might be tender. Full resuscitation measures should then be taken before further investigation.
A rectal examination is not recommended at initial presentation as it can distort the coning effect that you may see on the contrast study, indicating the transition zone between normal and abnormal bowel.
HD can uncommonly present outside the neonatal period with chronic constipation. However, HD is very rarely picked up in rectal biopsies of children with chronic constipation.
An abdominal X-ray will reveal distended bowel loops with no gas in the rectum. A lower gastrointestinal contrast enema may help to identify the coning transition zone between normal and abnormal bowel. The gold standard investigation is then a rectal suction biopsy.
This can be performed on babies up to six months old without the need for analgesia. The bowel is insensate at the site of the biopsies (usually 2-4cm above the dentate line) and so the baby generally tolerates the procedure well.
Parents are informed that there is likely to be some bleeding from the biopsy and there is a risk of bowel perforation.
A positive biopsy for HD will have no ganglion cells in the myenteric and submucosal plexus and will have an increase in acetylcholinesterase staining in association with hypertrophied nerve trunks.
The diagnosis can be devastating for parents. They have to quickly learn rectal irrigation in order to keep their baby's bowel decompressed.
When the baby has been fully resuscitated, rectal washouts are commenced. The stoma nurse specialist plays a vital role in this process. Parents' understanding should be bolstered with detailed written guidelines.
It is important to educate parents about the signs of enterocolitis. This will present with foul smelling diarrhoea, abdominal distension, vomiting and fever. It is the commonest cause of death in this patient group and urgent hospital admission is required for rehydration, antibiotics and more frequent rectal washouts. This information is equally important for GPs as this group of babies can be misdiagnosed with gastroenteritis.
Management at home
It is important that parents have easy access to the equipment. An initial one-week supply is provided by the hospital, thereafter community prescriptions are necessary for rectal tubes (size 10-14).
At home, parents need to establish a routine to allow for effective washouts once or twice a day. It may also be necessary to perform additional washouts or even to insert a rectal tube to release gas if there is abdominal distension. Some babies do pass stools spontaneously but this is not an indication to stop washouts.
|STEPS FOR RECTAL WASHOUT|
|1. Apply lubricating jelly to the rectal tube.
2. Add 30ml saline to the attached syringe.
3. Insert the rectal tube into the rectum (a few centimetres initially).
4. Allow the saline to run in.
5. Lower the rectal tube and allow it to empty.
6. Repeat the steps above, advancing the rectal tube each time until the effluent is clear and the abdomen is decompressed.
Regular contact with the stoma nurse specialist must be maintained. The parents must feel supported and encouraged. It is vital that the community nurse and health visitor are also involved, and that the baby is thriving in preparation for surgery. Detailed information regarding surgery can be given at the paediatric surgical clinic.
Most surgeons perform the surgery when the baby is three to six months old. Prior to surgery the child is given a washout with an added antibiotic. In our unit, the operation is carried out with laparoscopic assistance to first confirm the level of ganglionic bowel, and then mobilise the aganglionic segment down to the peritoneal reflection.
The distal aganglionic segment is mobilised from below moving inwards to meet the peritoneal reflection. The agangionic segment is pulled through the pelvis and the ganglionic level anastomosed close to the dentate line. The child should normally feed and stool within 24 hours, with the postoperative stay being three to five days.
The early stooling pattern can be frequent and cause significant skin breakdown around the perineum. This is managed with barrier creams.
All children are seen two weeks after discharge so that the anastomosis can be assessed and gently calibrated. Frequent review then takes place in the clinic to ensure stooling is adequate and weight gain appropriate.
It is important to emphasise to the parents that despite the removal of the affected bowel, there still remains a risk of enterocolitis, so they must remain vigilant.
In the longer term, this patient group does have a tendency to chronic constipation. It may take several years for children with HD to establish a normal a bowel habit. Up to 85 per cent achieve good bowel function with no soiling.
- Miss Duthie is a specialist registrar in paediatric surgery at Birmingham Children's Hospital, Miss Smith is a paediatric surgery nurse specialist, and Miss McCabe is a consultant paediatric surgeon, both Royal Hospital for Sick Children, Edinburgh
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