Urachus

Urachus
Vertical section of bladder, penis, and urethra. Urachus is seen at top
Urachus is #1
Identifiers
MeSH	D014497
Anatomical terminology [edit on Wikidata]

The urachus is a fibrous remnant of the

The remainder of this part of the urogenital sinus forms the body of the bladder and part of the prostatic urethra. The apex of the bladder stretches and is connected to the umbilicus as a narrow canal. This canal is initially open, but later closes as the urachus goes on to definitively form the median umbilical ligament.

Clinical significance

Failure of the inside of the urachus to be filled in leaves the urachus open. The telltale sign is leakage of urine through the umbilicus. This is often managed surgically. There are four anatomical causes:

• uroepithelium
  lining persists between these two structures.
• Urachal fistula: there is free communication between the bladder and umbilicus
• Urachal diverticulum (vesicourachal diverticulum): the bladder exhibits outpouching^[2]
• Urachal sinus: the pouch opens toward the umbilicus^[3]

The urachus is also subject to neoplasia. Urachal adenocarcinoma is histologically similar to adenocarcinoma of the bowel. Rarely, urachus carcinomas can metastasise to other regions of the body, including pelvic bones and the lung.^[4]

One urachal mass has been reported that was found to be a manifestation of IgG4-related disease.^[5]

Additional images

• 
  Inguinal fossae

References

This article incorporates text in the public domain from page 1213 of the 20th edition of Gray's Anatomy (1918)