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Portrait of Inferior vena cava

Anatomy · Heart & blood vessels

Inferior vena cava

Largest vein in the body

Abdomen and thorax · systemic veins

The largest vein in the body, returning deoxygenated blood from everything below the diaphragm to the right atrium. It begins at about L5 where the two common iliac veins unite, ascends on the right of the aorta behind the peritoneum, passes through the diaphragm at T8 and enters the right atrium almost at once.

How to spot them

  • ▸Formed at L5 by the union of the two common iliac veins, to the right of the midline
  • ▸Ascends on the right side of the aorta; the right crus of the diaphragm lies behind it
  • ▸Runs in a groove on the back of the liver just before piercing the diaphragm
  • ▸Receives the renal, hepatic and right gonadal veins; the left gonadal vein drains into the left renal vein instead

What to know

Formed at the fifth lumbar vertebra by the meeting of the two common iliac veins

Inferior vena cava.

Passes through the diaphragm at the level of the eighth thoracic vertebra, in the tendinous part

Inferior vena cava — the caval opening (T8).

It receives the hepatic veins at the back of the liver just below the diaphragm

Inferior vena cava — three hepatic veins join it here.

Receives the right gonadal vein directly, while the left one drains into the left renal vein

Inferior vena cava — an asymmetry that matters in left-sided varicocele.

A retroperitoneal vein lying to the right of the aorta and in front of the right psoas and the vertebral column

Inferior vena cava.

Compressed by the gravid uterus when a pregnant woman lies flat on her back, dropping blood pressure

Inferior vena cava — supine hypotensive syndrome.

A mesh basket placed inside it can trap clots travelling from the leg veins toward the lungs

Inferior vena cava filter.

Key ideas

  • Almost all its tributaries mirror the abdominal aorta's paired branches, except that the gut veins go via the portal vein to the liver first.
  • Because the liver sits in front of it and it is thin-walled with low pressure, its diameter changes with breathing and with volume status, a useful bedside ultrasound sign.

Quick-fire facts

  • •Formed at L5 by the union of the right and left common iliac veins.
  • •Passes through the caval opening of the diaphragm at T8; the oesophagus at T10; the aorta at T12.
  • •Drains the lower limbs, pelvis, abdominal wall, kidneys, suprarenals (right) and liver via the hepatic veins.
  • •The left renal vein is longer than the right because it must cross in front of the aorta; the left gonadal and left suprarenal veins drain into it.
  • •The right renal vein is short (about 2–3 cm), which is why the left kidney is preferred for donor nephrectomy.
  • •Valveless apart from a small rudimentary Eustachian valve at its entry into the right atrium.
  • •Left-sided and duplicated IVCs are uncommon congenital variants, found in well under 5% of people.
  • •It is roughly 20–25 cm long, most of it in the abdomen; only a very short stretch lies in the thorax.

Drill it — 7 cards

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Sources