Ascites

115 Ascites



Instruction


Examine this patient’s abdomen.



Salient features



History




• History of abdominal distension, dyspnoea


• History of pain abdomen: spontaneous bacterial peritionitis, malignancy


• History of heart failure, renal failure or liver disease


• History of TB (peritoneal TB)


• History of malignancy: mesothelioma, metastatic spread from primary tumours.



Examination




• Full flanks and umbilicus (Fig. 115.1)


• Presence of shifting dullness (always percuss with your finger parallel to the level of fluid)


• If the ascites is gross, use the ‘dipping’ method of palpation to feel the liver and spleen


• Look for stigmata of underlying disease (e.g. signs of cirrhosis, cardiac failure, renal failure or malignancy).


image

Fig. 115.1 Ascites, showing distended abdomen, dilated superficial collateral veins, haemorrhagic scratch marks and umbilical varices.


(With permission from Forbes A et al. 2005.)


Proceed as follows:



• Check for sacral oedema and swollen ankles.



Diagnosis


This patient has marked ascites and leg oedema with splenomegaly (lesions) caused by portal hypertension, the underlying cause needs to be investigated (aetiology).



Questions




What are the causes of a distended abdomen?


Fat, fluid, faeces, flatus and fetus.



What do you understand by the term ascites?


It is the pathological accumulation of fluid in the peritoneal cavity.



What are the common causes of ascitic fluid?




• Portal hypertension with cirrhosis


• Abdominal malignancy


• Congestive cardiac failure.



What investigations would you do to determine the underlying cause?


Diagnostic paracentesis for proteins and malignant cells, ultrasonography of the abdomen, peritoneal biopsy or laproscopy if the cause remains unclear.



What is the difference between an exudate and a transudate?


An exudate has a protein content of >25 g/l (see Case 97).



Advanced-level questions




What are the mechanisms of ascites formation in cirrhosis?




• It is caused by a combination of liver failure and portal hypertension. Liver failure decreases renal blood flow, resulting in retention of salt and water


• Secondary hyperaldosteronism caused by increased renin release and decreased metabolism of aldosterone by the liver


• Decreased metabolism of aldosterone by the liver


• Decreased metabolism of antidiuretic hormone


• Hypoalbuminaemia, which decreases colloid oncotic pressure


• Lymphatic obstruction, resulting in a ‘weeping’ liver


• Overproduction of nitric oxide has been proposed to be important in the pathogenesis of ascites sodium and water retention and hemodynamic abnormalities in cirrhosis (N Engl J Med 1998;339:533–41). Inhibition of nitric oxide synthesis improves sodium and water excretion in cirrhotic rats with ascities.

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Dec 4, 2016 | Posted by in GENERAL & FAMILY MEDICINE | Comments Off on Ascites

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