Failed embryologic closure of the omphalomesenteric duct results in a range of anomaliesincluding completely patent duct, umbilical polyp, Meckel's diverticulum, omphalomesentericduct cyst, or intraabdominal fibrous band. (See 'Embryology' above and 'Omphalomesentericduct anomalies' above.)●Failed embryologic closure of the urachus results in a range of anomalies including patenturachus, umbilical polyp, bladder diverticulum, or urachal cyst. (See 'Embryology' above and'Urachal anomalies' above and 'Umbilical polyp' above.)●Omphalitis, a polymicrobial infection of the umbilicus and surrounding tissue, occurspredominantly in the neonate. Complications include sepsis and necrotizing fasciitis, whichhas a high mortality rate. (See 'Omphalitis' above and 'Necrotizing fasciitis' above.)●Antibiotic treatment of omphalitis is required and is directed against Gram-positive andGram-negative organisms. We suggest initial parenteral administration of antistaphylococcaland aminoglycoside agents rather than topical or oral antibiotic therapy, in infants withomphalitis to reduce the risk of severe complications (Grade 2C). In communities with a highprevalence of methicillin-resistant Staphylococcus aureus, we suggest vancomycin beadministered rather than an antistaphylococcal penicillin (Grade 2C). (See 'Omphalitis'above.)Use of UpToDate is subject to the Subscription and License Agreement.