Case02

Parents bring their 2-day old infant for evaluation. The parents indicate that the infant started projectile vomiting the past two days, starting about 20 hours after birth and has had clean diapers since birth. The infant has been breast feeding since birth. On examination the infants' belly is distended and the vomit has a strong green/yellow coloration indicating bilious vomit (i.e. vomit containing bile). Respiration and heart rate are normal.

Question 2/2 - What tests would you perform to confirm or rule out conditions on your differential diagnosis?

Incorrect. CT wwould provide full diagnostic information on which condition the infant has. However, CT introduces more radiation than other possible studies without significant additional diagnostic utility in this case.

Children, especially infants, have higher radiation susceptibility as their brains and other organs are still developing, thus non-essential CT scans should be avoided.

Incorrect. MRI provide full diagnostic information on which condition the infant has. While the method is fully safe to use in infants as there is no radiation, the study is more time consuming and costly compared to other studies. It would only be used if the other studies were inconclusive.

The concern with a time consuming study such as MRI is the delay of surgical care if the condition turns out to be an apple peel atresia, which requires emergency surgery.

Correct! An x-ray is fast, cheap, and exposes the infant to minimal doses of radiation compared to other methods. Generally a non-contrast x-ray is taken then a second one with oral contrast.

A proximal obstruction (duodenal atresia) causes a classic “double bubble sign” on x-ray due to dilation of an air bubble in the stomach and proximal duodenum, with absent distal gas. A more distal obstruction (as in jejunal or ileal atresia) usually causes dilated loops of small bowel with air-fluid levels. Malrotation is also readily visualized and it is a priority to rapidly rule out malrotation as that is a surgical emergency.

If the plain shows signs of intestinal obstruction, most infants should be further evaluated with an upper gastrointestinal contrast study to localize the point of obstruction.

Correct! Ultrasound is reasonable at resolving an obstruction and a common first step when presenting with symptoms of obstruction (or could be suspected from prenatal ultrasound). Ultrasound is usually followed by additional more detailed imaging.

Incorrect. An exploratory laparotomy is an open surgical procedure involving a large abdominal incision to examine organs. As such it is invasive and high risk in an infant, this would never be used as a first diagnostic tool over various imaging techniques.