Expansion
Meckel's diverticulum, vitelline fistula, sinus, cyst and fibrous band
Expansion
The vitelline (omphalomesenteric) duct connects the midgut to the yolk sac and normally obliterates by week 9. Persistence gives:
- Meckel’s diverticulum - the intestinal end persists; by far the commonest, about 2 per cent
- Vitelline fistula - the whole duct persists, giving faeculent discharge from the umbilicus
- Vitelline sinus - the umbilical end persists, giving a discharging umbilical sinus
- Vitelline cyst (enterocystoma) - the middle persists as a cyst between two fibrous cords
- Fibrous band - a cord from ileum to umbilicus, around which small bowel can volvulate or become obstructed
The parallel set is the urachal anomalies, from the allantois: a patent urachus (urine from the umbilicus), urachal sinus, urachal cyst and a urachal diverticulum of the bladder.
An umbilical discharge in a neonate should therefore raise both possibilities, faeculent suggests vitelline, urinary suggests urachal.