Diagnosis of Congenital Malformations of the Gastrointestinal Tract

Sometimes babies are born with congenital malformations somewhere along the gastrointestinal (GI) tract. These malformations are rare and are not caused by prematurity. They range from minor to serious and can occur anywhere from the esophagus to the anus. Many of these conditions can be surgically treated, with an excellent chance at normal development and function later on as the baby grows into childhood and beyond. Other malformations have outcomes that are not as good.

Diagnosis of congenital abnormalities depends on the location of the abnormality along the GI tract. In general, abnormalities in the upper GI tract, for example, the esophagus, the stomach, and the duodenum, which connects the stomach to the small intestines, will be problematic more immediately. Abnormalities in the lower GI tract, such as the intestines, the rectum, and the anus, usually will take a little longer to become apparent.

Additionally, specific symptoms will depend on the specific location of the abnormality within the GI tract.

Diagnosing congenital malformations of the GI tract

Abnormalities, also called lesions, of the upper GI tract will have symptoms such as feeding intolerance and vomiting, possibly of both food and bile from the stomach. A distension or abnormal enlargement of the abdomen may also be apparent. At times, the stomach may continue to fill up but may not pass its contents further down the GI tract, enlarging the stomach to a surprisingly large extent. Meconium, a baby’s black and tarry first stool, may have passed or may continue to pass.

Intermediate lesions, found in the duodenum, will have similar symptoms as upper GI tract malformations. If there is distension of the abdomen, it may be even larger than the distension normally seen as a result of lesions of the upper GI tract.

In general, lesions of the lower GI tract have some or all the following symptoms: a delayed passage of meconium, poor passage of stool, and abdominal distension. If vomiting occurs, it usually does not occur immediately and it may contain feces.

Abdominal X-rays may reveal the malformation. It is also common to use both upper and lower GI tract tests called “series” when trying to diagnose a malformation. In these tests, a substance such as barium is given. The baby’s GI system is monitored with an X-ray machine called a fluoroscope as the barium makes its way through. This can reveal important details that will not be seen with X-ray. Even with fluoroscopy, diagnosis can remain unclear.

The usual blood tests will also be conducted to look for evidence of infection, electrolyte imbalances, hypoglycemia, or metabolic acidosis, among others.

Esophageal Atresia X-ray
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Normally, a very thin tube called a nasogastric tube can be passed down the esophagus and into the stomach. With an esophageal atresia, there is not a proper connection from the esophagus to the stomach. The nasogastric tube can only be passed as far down as the upper esophagus. There is usually a fistula, or small passageway, between the esophagus and trachea.
Bowel Obstruction X-ray
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The bowel pattern on the right is abnormal and is highly suggestive of an obstruction somewhere in the GI tract. The cause of the obstruction could be intestinal atresia, malrotation with volvulus, or Hirschprung's disease.

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Chris Tomlinson, MBChB, BSc