There are 2 venous solution that drain abdominal structures – the portal venous system and the systemic venous system. The portal system transports venous blood come the liver for processing, whilst the systemic venous system returns blood come the ideal atrium of the heart.

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In this article, us shall take into consideration the anatomy that these two venous solution – the major vessels involved, your anatomical course, and also their tributaries.

Systemic Venous System

The systemic venous device transports deoxygenated blood to the best atrium of the heart. The significant vessel in this device is the inferior vena cava.

Inferior Vena Cava

The inferior vena cava is the common convergence the venous drainage from every structures below the diaphragm. It is situated on the posterior abdominal muscle wall; anteriorly come the vertebral column and also to the right of the abdominal aorta.

The courage is formed by the union of the common iliac veins in ~ the L5 vertebral level. That ascends superiorly, and leaves the abdomen by piercing the main tendon the the diaphragm at the T8 level (the caval hiatus). In ~ the thorax, the worse vena cava drains right into the right atrium the the heart.

During its long course, the inferior vena cava shares an anatomical partnership with numerous ab structures – including the right typical iliac artery, the root of the mesentery, the head that the pancreas, the bile duct, the portal vein and also the liver.


The inferior vena cava is responsible for the venous drainage of every structures below the diaphragm. That receives tributaries from:

Common iliac veins – created by the external and internal iliac veins. They drain the reduced limbs and gluteal region.Lumbar veins – drainpipe the posterior ab wall.Right testicular/ovarian vein – drainpipe the appropriate testes or ovary dong in men and also women (the left testicular/ovarian vein drains into the left renal vein).Right suprarenal vein – drains the ideal adrenal gland (the left adrenal vein drains right into the left renal vein).

There room no tributaries native the spleen, pancreas, gallbladder or the abdominal part of the GI tract – as these structures are very first drained into the portal venous system. However, venous return native these frameworks ultimately enters the worse vena cava via the hepatic veins (after gift processed by the liver).

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Fig 1.0 – The inferior vena cava and significant tributaries. Note how the left adrenal vein and also left testicular vein empty right into the left renal vein.

Portal Venous System

The portal system carries venous blood (rich in nutrients that have been extract from food) come the liver because that processing.

The major vessel of the portal device is the portal vein. It is the allude of convergence because that the venous drainage of the spleen, pancreas, gallbladder and the abdominal part of the cradle tract. The portal vein is formed by the union of the splenic vein and also the superior mesenteric vein, posterior to the neck that the pancreas, in ~ the level of L2.

As it ascends towards the liver, the portal vein overcome posteriorly to the superior component of the duodenum and also the bile duct. Instantly before entering the liver, the portal vein divides into right and also left branches i beg your pardon then get in the parenchyma that the liver separately.


The portal vein is formed by the union of the splenic vein and also superior mesenteric vein. That receives added tributaries from:

Para-umbilical veins – drain the skin the the umbilical region.

Splenic Vein

The splenic vein is developed from a selection of smaller sized vessels as they leave the hilum of the spleen.

Unlike the splenic artery, the splenic vein is straight and also it maintains call with the body that the pancreas as it the cross the posterior abdominal wall. Together it reaches the neck that the pancreas, the splenic vein join the premium mesenteric vein to type the portal vein.


Tributaries come the splenic vein include:

Short gastric veins – drainpipe the fundus the the stomach.Left gastro-omental vein – drains the greater curvature the the stomach.

The inferior mesenteric vein drains blood indigenous the rectum, sigmoid colon, to decrease colon and also splenic flexure. It starts as the superior rectal vein and ascends, receiving tributaries from the sigmoid veins and also the left colic veins. Together it ascends additional it overcome posteriorly to the body of the pancreas and typically joins the splenic vein.

through TeachMeSeries Ltd (2021)

Fig 2 – The hepatic portal venous system.

Superior Mesenteric Vein

The exceptional mesenteric vein drains blood from the small intestine, cecum, ascending colon and also transverse colon. It begins in the right iliac fossa, together a convergence the the veins draining the terminal ileum, cecum and appendix. It ascends within the mesentery that the tiny intestine, and also then travel posteriorly to the neck of the pancreas to join the splenic vein.


Tributaries to the exceptional mesenteric vein include:

Right gastro-omental vein – drains the better curvature of the stomach.Ileocolic vein – drains the ileum, colon and also cecum.Right colic vein – drains the ascending colon.Middle colic vein – drains the transverse colon.

Many of this tributaries are created as an accompanying vein for each branch of the premium mesenteric artery.

Clinical relationship – Porto-Systemic Anastomoses

A porto-systemic anastomosis is a connection in between the veins the the portal venous system, and the veins that the systemic venous system. The significant sites of these anastomoses include:

Oesophageal – in between the oesophageal branch the the left gastric vein and also the oesophageal tributaries come the azygous system.Rectal – between the premium rectal vein and the inferior rectal veins.Retroperitoneal – between the portal tributaries that the mesenteric veins and also the retroperitoneal veins.Paraumbilical – in between the portal veins the the liver and also the veins that the anterior abdominal wall.
by TeachMeSeries Ltd (2021)

Fig 3 – Endoscopic figure of oesophageal varices. They can undergo rupture, top to large volumes of blood loss.

When blood flow through the portal mechanism is obstructed (e.g because of cirrhosis, portal vein thrombosis, or outside pressure from a tumour), the pressure within portal system increases. A portal venous press in excess of 20mmHg is defined as portal hypertension.

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In portal hypertension, blood might be re-directed with the porto-systemic anastomoses (as these are currently under a reduced pressure). If a big volume the blood passes through these anastomoses over a long duration of time, the veins roughly the anastomosis can become abnormally dilated – known as varices. Rupture of oesophageal or rectal varices can an outcome in fatal blood loss.