Differential Diagnosis for a 7-day-old Girl with Truncus Arteriosus and Abdominal Distension
- Single most likely diagnosis:
- Necrotizing Enterocolitis (NEC): This condition is a leading cause of morbidity and mortality in premature infants, but it can also occur in term infants, especially those with congenital heart disease. The presence of bright red blood in stool, abdominal distension, absent bowel sounds, and bilious fluid recovered from the nasogastric tube, along with the radiographic findings of dilated loops of bowel and air-fluid levels, are highly suggestive of NEC.
- Other Likely diagnoses:
- Intestinal Obstruction: The radiographic findings of multiple air-fluid levels and a paucity of gas in the distal colon/rectum suggest a distal obstruction. This could be due to various causes such as intestinal atresia, stenosis, or volvulus.
- Gastrointestinal Perforation: Although the abdominal x-ray does not show free air under the diaphragm, perforation cannot be entirely ruled out, especially if the patient's condition worsens or if a decubitus film is not obtained.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Septic Shock: The patient's low blood pressure, high pulse rate, and low temperature suggest sepsis, which can be deadly if not promptly treated. Sepsis can also lead to or exacerbate NEC.
- Cardiac Decompensation: The patient's underlying truncus arteriosus and signs of poor perfusion (low blood pressure, high pulse rate) raise the concern for cardiac decompensation, which would require immediate attention.
- Rare diagnoses:
- Hirschsprung's Disease: This congenital condition characterized by the absence of ganglion cells in the distal bowel can cause intestinal obstruction. However, it is less likely given the acute presentation and the presence of blood in stool.
- Meconium Ileus: This condition, associated with cystic fibrosis, involves obstruction of the small intestine due to inspissated meconium. It is a rare cause of intestinal obstruction in newborns but should be considered in the differential diagnosis.