The intestines form early in pregnancy as a long straight tube. Before the tenth week of pregnancy, they develop into the separate organs making up the digestive system. Occasionally, the intestines are not completely connected or blocked (atresia). Sometimes there is a partial blockage (web) inside the intestine.
Any part of the intestines can be affected by atresia or stenosis. Duodenal Atresia is one type. This occurs in around one in 6,000 births where the duodenum is closed off rather than being a tube. If the jejunum or ileum are affected, this is called ‘small bowel atresia’.
Small bowel atresia is more common than duodenal atresia. We do not know how exactly how many babies are born with small bowel atresia each year but we do know that it affects boys and girls equally. It is more common in twins or multiple births and babies born prematurely or with low birthweight.
Colonic atresia, affecting the large bowel, is very rare.
Small bowel atresia affects two areas of the small bowel – the jejunum and the ileum. The jejunum is the section of small bowel after the duodenum and is where the majority of nutrients are absorbed. The ileum is the main part of the small bowel, making up over half of its entire length, and connects to the large bowel. The blockage can affect any part of the ileum or jejunum.
What causes small bowel atresia?
More research is needed into the causes of small bowel atresia but currently doctors think that it is caused by reduced blood supply to sections of the bowel as the baby is developing in the womb. It is unlikely that it is caused by anything you did or did not do during pregnancy.
What are the signs and symptoms of small bowel atresia?
Many babies born with small bowel atresia appear well at birth but when they start to feed, they start to have nausea and vomiting and their vomit may be green. Their abdomen may appear swollen but soft and their skin may develop a yellow tinge (jaundice).
All newborn babies have meconium in their bowel. This is the dark green stool passed in the first day of life. Babies born with small bowel atresia may not pass any meconium at all or only a small amount. Not passing meconium does not prove that a baby has small bowel atresia but it may suggest it. Some babies with small bowel atresia pass meconium as expected.
How is small bowel atresia diagnosed?
When a baby with small bowel atresia is developing in the womb, they are may be surrounded by much more amniotic fluid than usual (polyhydramnios). Small bowel atresia can sometimes be suggested during pregnancy using an ultrasound scan.
After the baby is born, small bowel atresia is usually diagnosed when there are signs of an obstruction, such as vomiting, green bile and a swollen abdomen. An x-ray scan may show a blockage. Occasionally, doctors may suggest using a contrast scan and/or enema instead or as well as an x-ray.
Contrast scans and enemas use a thick, white liquid called barium or a clear liquid (contrast), both of which show up well on x-rays. The contrast cannot pass through the atresia suggests that atresia can be a cause.
How can small bowel atresia be treated?
Small bowel atresia is repaired in an operation under general anaesthetic. The operation to repair the atresia can is usually carried out using open surgery. Sometimes a laparoscopic surgery (key hole procedure) may help diagnose the problem so that it can be repaired using open surgery.
Are there any alternatives?
No. Small bowel atresia always requires surgical treatment to allow your baby to feed.
What happens before the operation?
Your baby will be transferred to the hospital soon after birth.
If your child is dehydrated, they will need a ‘drip’ of fluids for a while before the operation. Your child will also need a nasogastric tube, which is passed up the nose, down the foodpipe and into the stomach. This will drain off the stomach and bowel contents and ‘vent’ any air that has built up, which will make your child more comfortable.
When your child is stable, the surgeon will explain about the operation in more detail. Sometimes the atresia is suspected but may not be the only possible cause of the blockage. The surgeon will explain this to you.
What does the operation involve?
The surgeon will look at the bowel to determine the level of the blockage. If it is an atresia, this section is removed and the cut ends are joined together (anastomosis). This provides a clear passage for food and fluid to travel through your child’s intestine. The remainder of the small intestine will be checked for further atresias and treated if identified.
If it is not possible or safe to join the two ends together during the same procedure, the surgeon may bring the end of the intestine to an artificial opening (stoma) in the abdomen to form an ileostomy.
Are there any risks?
All surgery carries a small risk of bleeding during or after the operation. There is a chance that the area where the two ends of bowel were joined could start to leak, allowing bowel contents to escape into the abdomen. This is usually treated with antibiotics, but a second operation may be needed to check the leaking portion.
All abdominal surgery carries the risk of strictures forming. These are areas of scar tissue that can narrow the intestines, leading to obstruction. If your child vomits green bile and has a swollen abdomen, they should be reviewed urgently by a doctor.
It can take a while after the operation for the bowel to start working properly so your child may need to be fed intravenously using total parenteral nutrition (TPN) for a while. This affects many children.
What happens after the operation?
While your child’s intestines recover and start to work, they may be fed through a tube into their veins (total parenteral nutrition or TPN). This will gradually be replaced by breast or bottled milk, given through the naso-gastric tube when your child is able to tolerate this. As your baby recovers, you will be able to feed them from the breast or bottle. Over time, the drips and monitors will be removed one by one.Most children stay in hospital for one to two weeks, but occasionally a longer stay is needed.
What happens next?
The outlook depends on the amount of damage to the bowel. Adhesions can form after any abdominal surgery and can cause further problems such as blockage or pain. This however is quite rare and may sometimes require another operation to separate the adhesions.
