Congenital urachal anomalies

Congenital urachal anomalies are a spectrum of potential anomalies that can occur due to incomplete involution of the urachus.

Epidemiology

A urachal remnant occurs in approximately 1 in 5000 patients.

Pathology

The urachus connects the dome of the bladder to the umbilical cord during fetal life and is located behind the lower anterior abdominal wall and anterior to the peritoneum in the space of Retzius.

By birth, the urachus is obliterated and becomes a vestigial structure known as the median umbilical ligament (not to be confused with the medial umbilical ligament, which is a separate structure that lies laterally to the median umbilical ligament).

In the absence of complete obliteration, the urachus persists in a number of configurations depending on the location and degree of obliteration.

Classification

There are four types of congenital urachal remnant anomalies. They are:

• patent urachus
  • communication between the bladder and umbilicus through a urachus that has not involuted
  • commonest (~50%)
• urachal cyst
  • a fluid-filled dilatation of the mid urachus
  • next commonest (~30%)
• umbilical-urachal sinus
  • blind focal dilatation of the umbilical end of the urachus
  • ~15%
• vesicourachal diverticulum
  • blind focal dilatation of the bladder end of the urachus
  • ~5%

Treatment and prognosis

Congenital urachal remnants predispose to infection from urinary stasis and over a long period the remnant may develop malignancy (e.g. adenocarcinoma).

Treatment is not standardized. Some recommend surgical excision of the urachus if a remnant anomaly is present.