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Inferior epigastric artery

The inferior epigastric artery is a major branch of the external iliac artery that supplies the anterior abdominal wall. It runs upward within the rectus sheath and forms an important anastomosis with the superior epigastric artery, creating a continuous arterial supply to the abdominal wall. Clinically, it is a critical landmark in hernia surgery, flap reconstruction, and radiologic evaluation of the anterior abdominal wall.

Synonyms

  • Epigastric artery (inferior)

  • External iliac branch (inferior epigastric)

Origin, Course, and Termination

  • Origin:

    • Arises from the external iliac artery, just superior to the inguinal ligament and lateral to the origin of the deep circumflex iliac artery

  • Course:

    • Runs upward and medially, passing behind the inguinal ligament and the spermatic cord (or round ligament of uterus)

    • Enters the rectus sheath by piercing the transversalis fascia at the arcuate line

    • Travels superiorly between the rectus abdominis muscle and posterior rectus sheath

  • Termination:

    • Ascends toward the umbilicus and anastomoses with the superior epigastric artery (branch of the internal thoracic artery)

Relations

  • Anteriorly: Rectus abdominis muscle and anterior abdominal wall

  • Posteriorly: Transversalis fascia, peritoneum, and loops of small intestine in abdominal cavity

  • Medially: Median umbilical ligament

  • Laterally: Deep inguinal ring and spermatic cord (or round ligament)

Function

  • Supplies blood to the lower anterior abdominal wall, rectus abdominis muscle, and overlying skin

  • Provides collateral circulation with superior epigastric and intercostal arteries

  • Critical blood supply for surgical abdominal wall flaps (TRAM, DIEP flaps in plastic/reconstructive surgery)

Clinical Significance

  • Hernias: Landmark for distinguishing direct from indirect inguinal hernias (direct hernias occur medial, indirect lateral to the artery)

  • Flap surgery: Provides key pedicle for abdominal wall reconstruction (TRAM/DIEP flaps)

  • Iatrogenic injury: At risk in laparoscopic port placement and lower abdominal incisions

  • Aneurysm or pseudoaneurysm: Rare but may occur post-trauma or intervention

  • On imaging: Identifiable as a landmark in differentiating groin pathologies

MRI Appearance

T1-weighted images:

  • Appears as a flow void (dark tubular structure) along its course

  • Surrounding fat appears bright, outlining the artery

T2-weighted images:

  • Vessel lumen shows flow void (dark signal)

  • Adjacent fat and rectus sheath tissues visible

STIR (Short Tau Inversion Recovery):

  • Artery remains dark due to flow void

  • Fat signal suppressed, reducing contrast with surrounding tissues

T1 Fat-Sat Post-Contrast:

  • Enhances brightly and uniformly after gadolinium contrast

  • Vessel wall or pseudoaneurysm may show focal enhancement

CT Appearance

Non-Contrast CT:

  • Artery appears as a soft tissue density tubular structure, best seen with adjacent fat planes

  • Calcifications may be present in elderly or atherosclerotic patients

Post-Contrast CT (CTA):

  • Artery enhances brightly and homogeneously with intravenous contrast

  • Anastomosis with superior epigastric artery clearly demonstrated

  • Pseudoaneurysm or vascular malformation appears as focal enhancing outpouching

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