Inferior vena cava anatomy

Course

Begins opposite L5 Vertebra by the confluence of the two Common Iliac Veins behind the Right Common Iliac Artery
Runs upwards on the right of the Aorta
Grooves the bare area of the Liver
Pierces the Central Tendon of the Diaphragm at the level of T8 Vertebra
Lies on the bodies of the Lumbar Vertebra and the Right Crus of the Diaphragm
- Overlaps the Right Sympathetic Trunk
Crosses the following structures:
- Right Renal Artery
- Right Suprarenal Artery
- Right Inferior Phrenic Artery
Partly overlaps the Right Suprarenal Gland and Coeliac Ganglion

In the Infracolic Compartment:
- Lies behind the peritoneum of the posterior abdominal wall
- Crossed by:
  - Root of the Mesentery
  - Right Gonadal Artery
  - 3rd Part of the Duodenum
In the Supracolic Compartment:
- Lies at first behind the Portal Vein, Head of the Pancreas and the Bile Duct
- Then lies behind the peritoneum that forms the posterior wall of the Epiploic Foramen
Above this, lies behind the bare area of the Liver into which it excavates a deep groove
Inferior Vena Cava (and its tributaries) do not have valves (EXCEPT the Gonadal, esp. Testicular Veins)
Surface Marking: A vertical line 2.5cm to the right of the midline from the Inter-tubercular plane to the 6th costal cartilage

Tributaries Overview

Common Iliac Veins

Formed in front of the Sacroiliac joint by the union of the Internal Iliac and External Iliac Veins
- External Iliac Veins enter the abdomen on the medial side of its corresponding artery and runs along the pelvic brim
Left Common Iliac Vein
- Slightly longer than the Right due to the Inferior Vena Cava being located to the right of the midline
- Posteromedial to the Left Common Iliac Artery
- Joins the Right Common Iliac Vein almost at a right angle after bulging forwards across the body of L5 vertebra
Right Common Iliac Vein
- Almost vertical
- Lies posterior and then lateral to the Right Common Iliac Artery
Each Common Iliac Vein receives Iliolumbar and sometimes Lateral Sacral veins
- The left usually receives the Median Sacral Vein
  - Median Sacral Vein lies on the right side of the Median Sacral Artery

Lumbar Veins

Accompany the lumbar arteries
Drain the lateral and posterior abdominal walls
Anastomotic connections anteriorly with the Epigastric Veins and posteriorly with the Vertebral Venous Plexuses
The 4th and 3rd Lumbar Veins empty into the Inferior Vena Cava
- The veins from the left pass behind the Aorta
- All expected to lie behind the Sympathetic Trunks
  - Occasionally, one or more may lie in front
The 2nd and 1st Lumbar Veins do not usually reach the Inferior Vena Cava
- They join the Ascending Lumbar Vein which connects the Common Iliac, Iliolumbar, and Lumbar Veins
- Passes vertically upwards behind Psoas and in front of the Lumbar transverse processes
- Each Ascending Lumbar Vein joins the Subcostal Vein to form the Azygos Vein on the right and the Hemiazygos Vein on the left

Gonadal Veins

Accompany the Gonadal Arteries
Each is usually paired
Run up on Psoas with the two venae commitantes uniting
Right Gonadal Vein:
- Enters the Inferior Vena Cava just below the Renal Vein at an acute angle
- Right Testicular Vein may occasionally join the Renal Vein
Left Gonadal Vein:
- Invariably joins the Left Renal Vein at a right angle
Testicular Veins usually have valves at their terminations
- Valves may be present in the Ovarian Veins

Renal Veins

Lie anterior to the Renal Arteries
Lie behind the Pancreas
Joins the Inferior Vena Cava at right angles at the level of L2 Vertebra
Each emerges from the hilum as 5 or 6 tributaries which soon unite
Left Renal Vein:
- 3 x as long as the Right Renal Vein (7.5cm vs. 2.5cm)
- Usually crosses anterior to the Aorta
- Receives the Left Suprarenal Vein and Left Gonadal Vein and possibly a Left Inferior Phrenic Vein
- May have to be ligated and divided during surgery for Aortic Aneurysms
  - Provided this is done to the right of the point of entry of the Gonadal and Suprarenal Veins, the kidney is not harmed
- Variations:
  - Double Left Renal Vein – one vein passing anterior and one posterior to the Aorta
  - Only a posterior vein is present
- NB: Left Renal Vein connects the Azygos and Vertebral Venous Systems
Right Renal Vein:
- Usually only drains its own kidney
- Occasionally is joined by the Right Gonadal Vein

Suprarenal Veins

Left Suprarenal Vein:
- Runs downwards and medially to the Left Renal Vein
Right Suprarenal Vein:
- Very short vessel
- Passes horizontally to the posterior aspect of the Inferior Vena Cava behind the Bare Area of the Liver

Inferior Phrenic Veins

Accompany the arteries on the lower surface of the Diaphragm
Normally join the Inferior Vena Cava just below the liver
Left Inferior Phrenic Vein may join the Left Renal or Suprarenal Vein or be double and have different destinations

Hepatic Veins

Three main Hepatic Veins and several Accessory Hepatic Veins enter the Inferior Vena Cava as it lies in its groove on the back of the Liver

Embryology of the Inferior Vena Cava

At 4th week gestation – 3 different venous systems form:
- Vitelline system drains the gut
- Umbilical system drains Placenta
- Cardinal system drains the rest of the Embryo

Infrahepatic IVC develops from a set of 3 paired parallel veins appearing consecutively between 4-8 weeks of life
- Posterior Cardinal Vein
- Subcardinal Vein
- Supracardinal Vein
Suprahepatic IVC derived from cranial segment of Right Vitelline Vein
Retrohepatic segment derived from an anastomosis between the cranial segment of the Right Subcardinal Vein and Right Vitelline Vein
Infra-hepatic/Suprarenal IVC derived from Right Subcardinal Vein
Renal Collar is formed from anastomoses between the Supracardinal veins posteriorly and the Subcardinal veins anteriorly, with the posterior limb regressing during development
On the right, the anterior limb is incorporated into the lateral wall of the renal segment of the IVC
On the left, the anterior limb forms the normal adult Left Renal Vein
The suprarenal portions of the right and left Supracardinal Veins connect with the Posterior Cardinal veins forming the Azygos and Hemiazygos systems, respectively
The infrarenal portions disappear on the left but form the infrarenal portion of the IVC on the right
The Posterior Cardinal Veins mostly regress except for the distal portion, which later become the iliac confluence and future iliac veins, and the proximal portion, which joins the Azygos and the Hemiazygos veins

GenSurg.nz