Median Umbilical Ligament

1. Overview

The median umbilical ligament is a fibrous, cord-like remnant of the embryonic urachus, which originally connected the fetal bladder to the umbilicus. After birth, the urachus obliterates and becomes the median umbilical ligament. Although functionless in adults, it is an important surgical and anatomical landmark on the internal surface of the anterior abdominal wall, running from the apex of the urinary bladder to the umbilicus.

2. Location

The median umbilical ligament is located in the midline of the anterior abdominal wall, within the extraperitoneal connective tissue of the retropubic space (space of Retzius). Key anatomical relationships include:

• Extends from the bladder apex to the umbilicus.

• Positioned posterior to the anterior abdominal wall and anterior to the peritoneum.

• Flanked by the medial umbilical ligaments (remnants of the umbilical arteries).

• Forms the central elevation of the median umbilical fold, visible during laparoscopic or open abdominal surgery.

3. Structure

The median umbilical ligament is a fibrous band composed of dense connective tissue. It is the obliterated form of the urachus—a canal lined by transitional epithelium during fetal development. Structural features include:

• Length: Approximately 5–10 cm in adults.

• Composition: Collagen and fibroblasts with no vascular or epithelial content in its adult form.

• Embryologic origin: Derived from the allantois, a part of the primitive hindgut involved in early fluid exchange.

4. Function

In the adult, the median umbilical ligament has no physiological function. However, in fetal life, its precursor—the urachus—serves important developmental roles:

• Urine drainage in fetus: Allows passage of fetal urine from the bladder to the allantoic sac and umbilical cord.

• Involution post-birth: Normally becomes obliterated and fibrosed by the first few months of life.

5. Physiological Role(s)

Though physiologically inert in adulthood, the median umbilical ligament is significant in terms of spatial orientation within the abdomen:

• Surgical landmark: Guides laparoscopic surgeons during procedures like hernia repairs, bladder access, and peritoneal entry.

• Fetal physiology (as urachus): Aids in waste elimination and fluid exchange before full urinary tract development.

6. Clinical Significance

Urachal Anomalies

Failure of the urachus to fully obliterate can result in urachal remnants, which may present as:

• Patent urachus: Persistent communication between bladder and umbilicus → urine leakage from the navel.

• Urachal cyst: Fluid-filled sac along the urachus → may become infected or cause pain.

• Urachal sinus or diverticulum: Partial obliterations leading to infection or urinary symptoms.

Diagnosis is made via ultrasound, CT scan, or fistulography. Surgical excision is often curative.

Urachal Carcinoma

A rare but aggressive cancer that can arise from urachal remnants, typically adenocarcinoma. Presents with:

• Hematuria

• Suprapubic mass

• Umbilical discharge (in advanced cases)

Requires wide surgical excision with partial cystectomy and sometimes en bloc resection of the ligament and umbilicus.

Surgical Relevance

During laparoscopic procedures, the median umbilical fold (raised by the underlying ligament) helps differentiate midline structures. It is critical to avoid inadvertent injury to bladder or vascular structures during dissection near this area.

Hernias

The supravesical fossa, located between the median and medial umbilical folds, is a site of potential supravesical hernias, which are rare but clinically relevant in cases of bowel obstruction.

Imaging Findings

Urachal remnants or anomalies may be detected on:

• Ultrasound: Shows midline cystic or tubular structures anterior to the bladder.

• CT/MRI: Useful for preoperative planning and identification of malignancy or abscess formation.