Anterior (Transperitoneal) Approach to the Lumbar Spine

Gray’s Anatomy illustration of the abdominal aorta
The abdominal aorta and its branches. The aortic bifurcation usually sits at L4, which shapes access to the L4 to S1 discs through the anterior approach. Image by Henry Vandyke Carter, Gray’s Anatomy (1918), Wikimedia Commons, public domain.

Indications

  • Fusing L5 to S1
  • Not for occasional user

Position

  • supine
  • prep & drape for 2 incisions
  • GA
  • urinary catheter
  • nasogastric tube
    • ileus is common

Landmarks

  • umbilicus
    • opposite L3-4 disc space
  • pubic symphysis

Incision

  • longitudinal midline incision
  • Start: xiphisternum
  • Curved to the LEFT around umbilicus
  • End: pubic symphysis

Internervous Plane

  • Abdominal muscles on each side
    • Segmentally supplied by branches from 7th to 12th intercostal nerves

Superficial Dissection

  • Deepen wound in line with incision
    • Fat
  • Rectus sheath
    • Incise longitudinally
    • Reveals 2 rectus muscles
    • Separate with fingers
  • Peritoneum
    • Pick up with pair of forceps & incise with knife
    • Extend incision watching for viscera, bladder

Deep Dissection

  • Balfour self retaining retractor
    • Retract viscera laterally
  • Put table in Trendelenburg’s position of 30°
    • Carefully pack bowel cephalad
  • Infiltrate tissue over anterior surface of sacral promontory with a few millilitres of saline
    • Makes dissection easier
    • Helps identify presacral parasympathetic nerves
  • Ligate sacral artery
    • Runs down midline
  • Identify L5-S1 disc space
    • Palpate sharp angle
    • I.I
    • Lies below aorta bifurcation

Dangers

  • Presacral plexus of parasympathetic nerves
    • Retroejaculation & impotence
  • Vessels
    • Middle sacral artery
    • Aorta
    • IVC
  • Ureter

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.