Differential Diagnosis for the 4-hour-old Boy
- Single most likely diagnosis
- Umbilical hernia: This is the most likely diagnosis given the presence of a soft mass inferior to the umbilical stump that increases in size with crying (which increases intra-abdominal pressure) and reduces with gentle pressure. The fact that it is covered by skin and not tender to palpation also supports this diagnosis.
- Other Likely diagnoses
- Omphalocele (small): Although less likely than an umbilical hernia due to the description of the mass being covered by skin, a small omphalocele could present similarly. However, omphaloceles typically involve a larger defect and may contain more than just intestinal contents.
- Gastroschisis (small): Similar to omphalocele, a small gastroschisis could potentially present with a mass near the umbilical stump, but it usually involves a defect to the right of the umbilicus and the bowel is not covered by a sac.
- Do Not Miss diagnoses
- Intestinal obstruction (e.g., due to a volvulus or intussusception): Although the infant is currently asymptomatic, any abdominal mass in a newborn warrants consideration of intestinal obstruction, which can rapidly become a life-threatening condition.
- Necrotizing enterocolitis: This condition, although more common in premature infants, can occur in term infants and presents with abdominal distension, tenderness, and sometimes a mass. It is a medical emergency.
- Rare diagnoses
- Urachal cyst or sinus: These are remnants of the allantois and can present as a midline abdominal mass. They are less common and might not reduce with pressure as easily as an umbilical hernia.
- Mesenchymal hamartoma: A rare benign tumor that could present as an abdominal mass, but this would be unusual in the newborn period and not typically associated with the umbilical stump.