Imperforate anus (anorectal malformation) in babies: signs, surgery and outlook

Bladder & Bowel UK explains that anorectal refers to the last part of the bowel: the anus, the opening through which poos are pushed out, and the rectum, the part of bowel before the anus. An anorectal malformation (ARM) is a group of conditions some babies are born with that affect the anus and rectum, according to Royal Manchester Children's Hospital.

The abnormality varies. Bladder & Bowel UK says the most common problem is imperforate anus, which is the absence of a normal anal opening. It describes forms in which the rectum ends in a blind pouch that does not connect with the anus, the rectum connects to the urinary or reproductive system so that poo leaks out at the wrong place, or the anus is narrowed (stenosis) or absent.

Royal Manchester Children's Hospital lists the common types. Anal stenosis is when the anal opening is too small so that poo cannot easily be pushed through, and babies may strain or pass a very thin poo. Imperforate anus without a fistula is when the baby is born without an opening on the skin and the rectum is closed off. ARM with a fistula is when the rectum abnormally connects through a small tunnel of tissue to the skin between where the hole should be and the vagina or scrotum, or in boys sometimes to the urethra or bladder, so that poo may be passed from the penis.

Bladder & Bowel UK's diagrams show both 'high' and 'low' defects, in boys and in girls, and its guide notes that the type of surgery will depend on the malformation.

Royal Manchester Children's Hospital lists the signs, which depend on the type: the baby has not had a poo by 2 days old, there is no hole for poo to come out, the opening is in a different place from where it should be (closer to the vagina or scrotum), poo leaks from the penis or around the vagina, poo is mixed with urine, vomiting, and swelling of the tummy.

Because a doctor can diagnose an ARM by looking at the baby after birth, it is usually recognised soon after delivery. The NHS newborn physical examination, done within 72 hours of birth and again at 6 to 8 weeks, is intended to find general problems so they can be treated early, and your midwife, health visitor or GP should be told promptly if a baby is not passing poo or has a swollen tummy or vomiting.

Both sources describe the VACTERL group of conditions that an ARM is often associated with: vertebral (spine) abnormalities, anal malformation, cardiac (heart) defects, tracheal (windpipe) problems, oesophageal (food pipe) problems, renal (kidney and urinary tract) malformations and limb defects. Royal Manchester Children's Hospital says a baby is likely to have tests to check for problems with these body parts. Bladder & Bowel UK says Down syndrome, Hirschsprung's disease and narrowing of the intestine (duodenal atresia) may also be seen, and that the incidence of ARMs is increased in children with Down syndrome.

Investigations before surgery may include abdominal X-rays, abdominal and spinal ultrasound, an MRI scan, and an ECG to check for heart problems, according to Bladder & Bowel UK. Because some children have associated bladder problems, checks should be done to ensure the bladder is working normally.

Royal Manchester Children's Hospital explains that without an anal opening in the correct place a baby has difficulty passing poo, which can lead to a blockage in the bowel and, if untreated, weakening and tearing of the bowel wall. While waiting for operation babies are likely to need a nasogastric tube to empty the stomach and prevent vomiting and a drip for fluids and antibiotics.

Royal Manchester Children's Hospital lists potential risks after surgery as bleeding, infection, breakdown of the wound, damage to surrounding structures, narrowing of the anal opening and mucosal prolapse. It says caring for the skin around the bottom is important because it can be very sensitive and that the team will show parents how to do this.

Bladder & Bowel UK notes that a colostomy can be a scary thing to contemplate initially, but that support is available from stoma nurses or paediatric community nurses who show parents how to care for it and how to obtain supplies.

Royal Manchester Children's Hospital says each baby is different: some will grow up to have normal bowel function, but most will need long-term medication for constipation (laxatives) or help with continence, and a small number will need a permanent colostomy. It reviews babies with ARM in clinic until around 16 years old.

Bladder & Bowel UK says the majority of children achieve full continence, although they may need extra help, and that if the abnormality was extensive the child may need further surgery or regular bowel washouts. It recommends that all children start a bowel management programme as soon as possible after surgical correction is complete and before potty training. Constipation can be a problem and should be treated promptly with laxatives, good fluid intake and diet. Paediatric continence advisors and specialist nurses can support families with soiling, toilet training and constipation, and products to contain faeces may be supplied through the NHS.

Anorectal malformations are treated on the NHS in specialist children's surgical services, such as the Manchester Centre for Neonatal Surgery whose parent information is used here, with continence advisors and stoma nurses supporting families. Private paediatric surgery exists, and the staged operations are the same. Ask which team will be responsible for your child in the long term and how to contact them if there is a problem with the stoma or bowel.