University Hospital Southampton NHS Foundation Trust

Small bowel atresia

The small bowel is the section of bowel between the stomach and the large bowel (colon). It is about 300cm long in a newborn baby at full term and its function is to absorb food.

An atresia is a gap in the bowel causing a complete blockage (obstruction) of the bowel. It occurs in about 1 in 5000 babies.

Small bowel atresiaWhy does it occur?

Atresia is believed to be caused by damage to the blood vessels of the bowel. It is not known why the blood vessels are damaged but this damage can happen at any time during pregnancy.

Most commonly, the bowel is blocked but none is missing. In some babies there is a section missing and although usually this is an insignificant amount, in some babies it may be enough to interfere with the baby's ability to absorb milk.

Babies can have over half the bowel missing without there being much effect on milk (or later, food) absorption. However in some babies there is so much bowel missing that special feeding is needed. This is known as short bowel syndrome. It could mean long term hospitalisation and drip feeding. Sadly many of these babies do not survive.

Initial management

Babies with small bowel atresia vomit soon after birth and the vomit is bile-stained (green), after which:

  • Milk feeds will be stopped.
  • A tube will be passed through the nose into the stomach to drain away any fluid and air collecting in it.
  • Fluids will be given through a vein (drip).

How is the diagnosis made?

In a few babies the diagnosis may be suspected on antenatal ultrasound scan. There are a number of causes of blockage other than atresia. An x-ray of the baby's abdomen may suggest a blockage but the final diagnosis of atresia may only be made at operation.

How is the atresia treated?

An operation will be necessary in the first few days of life. The ends of the atresia are cut away and the bowel joined back together. This is usually a simple procedure.

After the operation

Small amounts of milk are usually started after 2 or 3 days and gradually increased. Most babies are able to go home about 2 weeks after the operation. If the section of bowel above the blockage has become very dilated before birth it may take longer to start working and so some babies need to stay longer.

During this time your baby will need drip feeds (Parenteral Nutrition) through a long line. This line is usually placed in a small vein in an arm or leg and fed through into a large vein. Sometimes an operation under anaesthetic is necessary to insert the line directly into a large vein.

It should be possible for the baby to grow quite normally on this form of feeding while the bowel is recovering. Milk feeds will be slowly introduced and increased, as the baby is able to tolerate them. Once recovery has begun the baby should be able to feed normally, either by bottle or breast.

What are the long term effects?

Provided there is plenty of bowel length there are no long term consequences of small bowel atresia. If a moderate amount of bowel is missing the baby may have rather loose and frequent bowel motions but this tends to improve over a few months.

Following an operation there is always a small risk of future obstruction occurring. If your baby has a bilious vomit or a distended abdomen medical advice should be sought.

What is the after care for small bowel atresia?

Following discharge your baby will be seen in the outpatients department by members of the surgical team, where help and advice will be available to you. It is usually possible for this follow up to take place in your local hospital.

Parent to parent link

Many parents who have experienced this same condition with their baby have indicated that they would be willing to speak to other  parents. If you would like make use of this service please talk to our staff or contact us.


University Hospital Southampton NHS Foundation Trust produce guidelines as an aid to good clinical practice. They represent recognised methods and techniques of clinical practice, based on published evidence. The ultimate judgement regarding a particular clinical procedure or treatment must be made by the clinician in the light of the clinical data presented by the patient and the diagnostic or treatment options available. The guidelines issued are not intended to be prescriptive directions defining a single course of management and departure from the local guidelines should be fully documented in the patient's case notes at the time the relevant decision is taken.