The urachus is the fibrous vestigial remnant of the fetal allantois.

The lumen of the urachus usually obliterates after birth and it becomes the median umbilical ligament, a midline linear fibrous fold of parietal peritoneum, extending from the apex of the bladder to the umbilicus. It is located in the retropubic space.

If the lumen does not completely involute, a spectrum of urachal remnants may persist, including:

A urachal remnant may develop adenocarcinoma.


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Article information

rID: 24418
System: Urogenital
Section: Anatomy
Synonyms or Alternate Spellings:
  • Median umbilical ligament

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Cases and figures

  • Figure 1: urachus - indicated by arrows
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  • Case 1: prominent urachus
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