Final answer:
A 1-week old infant with symptoms of bilious vomiting, leg drawing, and abdominal distension is suggestive of a diagnosis of intestinal obstruction, such as intestinal atresia, malrotation with volvulus, or Hirschsprung's disease. These conditions involve either a physical or functional obstruction, leading to accumulation of gas and fluids in the bowels, and require urgent medical attention.
Step-by-step explanation:
A 1-week old baby presenting with bilious vomiting, leg drawing, and abdominal distension may have a number of possible diagnoses, but the symptoms are highly suggestive of an intestinal obstruction such as intestinal atresia, malrotation with volvulus, or Hirschsprung's disease. The pathophysiology behind these conditions usually involves a physical obstruction (atresia or volvulus) or a functional obstruction due to lack of nerve cells in the bowel wall (as in Hirschsprung's disease).
Bilious vomiting indicates the obstruction is likely to be distal to where the bile duct enters the intestine, since bile is entering the vomitus. Leg drawing and abdominal distension are further clinical signs that suggest severe discomfort and the accumulation of gas and fluids in the obstructed bowel segment. These conditions require urgent medical assessment, typically including imaging studies and laboratory tests, followed by appropriate surgical intervention to relieve the obstruction.
During the neonatal period, it is critical for meconium to be cleared from the intestines to prevent obstruction, and to monitor bilirubin levels to avoid hyperbilirubinemia which can be toxic to the developing brain.