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Median umbilical ligament

The median umbilical ligament is a fibrous midline structure extending from the apex of the urinary bladder to the umbilicus. It represents the fibrotic remnant of the embryonic urachus, a canal that connects the fetal bladder to the allantois during development. In adults, it has no functional role but serves as an important anatomical and radiological landmark in the anterior abdominal wall and pelvic cavity.

It runs in the preperitoneal space of Retzius and is covered by the parietal peritoneum, which raises a midline fold on the inner surface of the anterior abdominal wall — the median umbilical fold. Its recognition is crucial in surgical procedures such as laparoscopic port placement and pelvic dissections, as well as in the assessment of urachal anomalies.

Synonyms

  • Urachal remnant

  • Fibrous urachus

  • Midline umbilical ligament

Origin, Course, and Insertion

  • Origin: Apex (anterosuperior surface) of the urinary bladder

  • Course: Runs upward in the midline through the extraperitoneal tissue of the anterior abdominal wall, within the space of Retzius, forming the median umbilical fold of peritoneum

  • Insertion: Umbilicus

Relations

  • Anteriorly: Parietal peritoneum and anterior abdominal wall

  • Posteriorly: Extraperitoneal fat and fascia of Retzius

  • Inferiorly: Apex of the urinary bladder

  • Superiorly: Umbilicus

  • Laterally: Medial umbilical ligaments (remnants of umbilical arteries)

Function

  • No active function in adults

  • Represents the obliterated urachus (fetal connection between bladder and allantois)

  • Serves as a surgical and radiological landmark in pelvic anatomy

Clinical Significance

  • Remnants of the urachus may persist and cause urachal anomalies such as cysts, sinus, diverticulum, or fistula

  • Can be a site of infection (urachal abscess) or rare urachal carcinoma

  • Important surgical landmark in pelvic and laparoscopic surgery

  • Midline reference structure in abdominal imaging and dissection

MRI Appearance

T1-weighted images:

  • Median umbilical ligament appears as a thin, low-signal intensity band from bladder apex to umbilicus

  • Urachal cyst or carcinoma may appear as focal or mass-like structures with variable signal intensities

T2-weighted images:

  • Normal ligament shows low signal intensity

  • Fluid-containing urachal remnants (e.g., cysts) appear bright

STIR (Short Tau Inversion Recovery):

  • Normal ligament remains dark

  • Fluid or inflamed urachal remnants appear bright

Proton Density Fat-Sat (PD FS):

  • Ligament shows low baseline signal

  • Urachal pathology shows localized bright signal intensity

T1 Fat-Sat Post-Contrast:

  • Normal ligament shows no significant enhancement

  • Infected urachal remnants or carcinoma show heterogeneous or rim enhancement

CT Appearance

Non-Contrast CT:

  • Appears as a thin, soft-tissue density band extending from bladder apex to umbilicus

  • Urachal cysts appear as fluid-density lesions; calcifications may indicate carcinoma

Post-Contrast CT:

  • Normal ligament shows minimal or no enhancement

  • Urachal carcinoma or abscess shows irregular or rim enhancement with central low attenuation

MRI image

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MRI image

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MRI image

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CT image

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