History

During a clinical placement on a medical ward, the specialist registrar challenges you to make "an end of the bed diagnosis." The patient is a 49 year old man, a former smoker, who presented with severe dyspnoea and pitting oedema in the lower limbs. He has a history of recurrent deep venous thrombosis and pulmonary embolism. From the end of the bed you can see the patient is wearing a face mask providing high flow oxygen, his jugular venous pressure is markedly raised, and the appearance of his abdomen is grossly abnormal (figure below).

Questions

1. Describe the gross abnormality seen on the patient's abdomen.
2. What diagnosis can be made from the end of the bed?
3. What is the most likely cause of this condition?
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Answers

1. The patient's abdomen is abnormal because of several grossly dilated tortuous veins. One especially prominent vessel runs through the centre of the epigastrium.
2. Given the extent of the abnormality and the pattern of distribution of the vessels, the patient has a serious obstruction of the inferior vena cava.
3. The most likely cause of obstruction of the inferior vena cava is a malignant tumour spreading from one of the abdominal viscera.



Discussion

Obstruction of the inferior vena cava was first described by William Osler in 1879, however, at that time it was a diagnosis generally made after death. Nowadays the diagnosis can be made during life, with the help of modern imaging modalities. The clinical diagnosis may be confirmed using plain radiographs, computed tomography scanning,¹ or ultrasound.²

Severity of the condition and the pattern of symptoms can differ depending on the level of occlusion within the vessel. If the obstruction is above the renal veins then these vessels may also clot, causing nephrotic syndrome.¹³ Thrombosis in the inferior vena cava may predispose the patient to recurrent pulmonary emboli.³

In cases of chronic venous obstruction, collateral vessels become engorged with blood trying to bypass the blockage. If these collateral veins are superficial then they become visible through the skin, as can be seen in this patient. The other well known example of this phenomenon is "caput medusea," seen in portal hypertension and it may also occur when the inferior vena cava is obstructed if the hepatic vein is involved.³

The patient will be breathless because the decrease in venous return to the heart will eventually cause congestive cardiac failure. The problems of fluid overload and oedema are further compounded because the kidneys will then be underperfused, leading to renal ischaemia. This causes the juxtaglomerular apparatus to produce more renin, leading to an increase in aldosterone, via the renin-angiotensin-aldosterone system. Aldosterone acts on the renal tubules to retain sodium and therefore water. Also if the liver is involved because of hepatic vein occlusion, the patient may develop ascities.³

Obstruction of the inferior vena cava is relatively rare compared to obstruction of the superior vena cava. As stated above, the most likely cause is malignant in origin--either primary malignancy or metastases in the abdomen. The tumour grows and starts to press directly on to the vessel from the outside. In more advanced or aggressive tumours, they may invade the vessel wall. Siqueria-Filho et al, found that in 64 cases of obstruction of the inferior vena cava, carcinoma of the kidney was responsible for 31% of cases.⁴ However, they also described nine of the cases as idiopathic or primary obstructions because they could find no discernable cause.

In this man's case, however, the disease had been long standing--about 20 years in duration, making the diagnosis of neoplasia far less likely.

The second most likely cause of venous obstruction is thrombosis within the lumen of the vessel. Thrombosis is essential in maintaining homoeostasis in the event of haemorrhage; however, in this case it is obviously not a beneficial response. Rudolph Virchow listed three factors which would promote thrombus formation:

• Changes in the endothelial layer of the vessel-- perhaps due to trauma, either mechanical or chemical.
• Changes in the dynamics of blood flow-- for example due to external pressure from a large tumour or aortic aneurysm.
• Changes in the constituents of the blood-- for example thrombocytosis

Acquired factors such as smoking, use of the oral contraceptive pill, and the nephrotic syndrome are thought to increase the risk of venous thrombosis.

The man on whom this report is based has had the possible cause of his obstruction investigated exhaustively. So far no definite causative factors have been identified.

What causes obstruction of the inferior vena cava?



The possible causes leading to an obstruction of this great vessel include:

Neoplasia--This is by far the most common predisposing condition. It results in obstruction either by direct invasion, external pressure, thrombosis--or even tumour of inferior vena cava wall itself. However this is very rare

Thrombosis--For example, in individuals with polycythaemia or congenital clotting disorders, such as factor V Leiden and deficiencies in protein C, protein S, or antithrombin III.

Liver or pancreatic disease

Lymphadenopoathy of paravertebral peritoneal lymph nodes

Fibrous adhesions--These are common in individuals who have had previous abdominal surgery

Aortic aneurysm--Which is thought in some cases to press directly on the vessel

Congenital

Embolism

Iatrogenic--For example, accidental surgical clamping

Unexpectedly, however, even seemingly innocuous activities such as competing in a long hurdles race or doing tumbling exercises have also been reported as leading to obstruction of the inferior vena cava.³

Stephen Goldie fifth year medical student, University of Glasgow

Email: Stephen_Goldie@Hotmail.com

Stephen Bicknell consultant physician, Gartnavel General Hospital, Glasgow

June 2004



1. Voegeli DR, Lieberman RP, Yandow DR. Inferior vena cava obstruction presenting as an abdominal mass. Radiology 1983;149:73-4.
2. Walter DF, Ramaiya LI. Intermittent inferior vena caval obstruction: an unusual cause demonstrated by ultrasound. Br J Radiol 1991;64:173-4.
3. Missal ME, Robinson JA, Tatum RW. Inferior vena cava obstruction. Ann Intern Med 1965;62:133-61.
4. Siqueira-Filho AG, Kottke BA, Miller WE. Primary inferior vena cava thrombosis: report of nine cases. Arch Intern Med 1976;136:799-802.

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