Diagnosis of - Pearls And Pitfalls

M Maiya

Ascites is the accumulation of the fluid in the peritoneal Table I. Causes of Ascites cavity seen in variety of disease states. It is usually a clinical finding confirmed by diagnostic paracentesis, but sub-clinical Normal Peritoneum: amount of fluid as little as 100ml may be detected by a. Portal hypertension (SAAG > 1.1g/dl) abdominal sonography1. The various causes of ascites and  Hepatic congestion: CHF, constrictive peri-carditis, its pathogenesis are mentioned in Table I. The common Tricuspid insufficiency, Budd - Chiari. Syndrome. causes of ascites in India are chronic disease with  Liver disease: Cirrhosis, alcoholic hepatitis, Fulminant portal hypertension, congestive cardiac failure, abdominal hepatic failure, massive hepatic metastasis. tuberculosis, malignancy and hypoproteinaemia due to b. Hypo-albuminaemia: (SAAG <1.1g/dl) malnutrition.  Nephrotic syndrome  Protein losing enteropathy DIAGNOSIS  Severe malnutrition with anasarca Ascites may be one of the manifestations of the primary c. Miscellaneous condition (SAAG <1.1g/dl) disease or a part of the complication of the disease due to  Chylous Ascites tuberculosis or malignancy. It may also present as a sole  Pancreatic Ascites manifestation. Diagnosis is established by history, clinical  Bile Ascites examination, imaging and study of ascetic fluid.  Ovarian disease Diseased Peritoneum: (SAAG <1.1g/dl) HISTORY AND PHYSICAL EXAMINATION a. Infections: Mild and ascites of gradual onset may not have any symptoms.  Bacterial Peritonitis However, the patients with moderate and large ascites  Tubercular Peritonitis complain of increasing distension of appearance  Fungal Peritonitis of and exertional dyspnoea especially when it is  HIV associated Peritonitis large. Further, history pertaining to the primary disease has b. Malignant Conditions: to be obtained. History of alcohol consumption, drug abuse  Peritoneal Carcinomatosis and hepatitis suggest cirrhosis of liver. Symptoms of heart  Primary mesothelioma failure, presence of malignancy elsewhere, prolonged fever  Pseudomyxoma Peritonei may indicate cardiac, malignant and tubercular etiology  Hepato-Cellular Carcinoma respectively.  Lymphomas and leukemia's c. Other rare conditions: reveals, distended abdomen, flank  Vasculitis dullness, shifting dullness and fluid thrill. While the diagnosis  Esinophic peritonitis 386 Medicine Update-2011

Table II. Physical Examination

is obvious in patients with large ascites, the accuracy of per dl. physical assessment in mild and moderate ascites is only SAAG 50%, even in the hands of experienced gastro-enterologists2. The serum ascites albumin gradient (SAAG) has been found Flank dullness is sensitive but shifting dullness is more to be more accurate in the differential diagnosis of ascites3. specific. Fluid thrill may be present in conditions other The gradient is calculated by substracting the ascetic fluid than ascites like, large ovarian or hydatid cyst, pregnancy albumin level from the serum level obtained on the same with hydromnias and focal ascites. Physical examination day. The SAAG is the best single test for classifying ascites may provide a clue for the etiology as mentioned in Table into portal hypertensive (SAAG > 1.1g/dl) and non portal II. Evaluation must include assessment of hepatic, renal and hypertensive (SAAG <1.1g/dl) types. The classification of cardiac functions. ascites based SAAG is shown in Table IV.4 Table IV. Classification of types of Ascites according to INVESTIGATIONS the level of SAAG In patients with new onset ascites of unknown origin, peritoneal fluid should be examined for tests shown in Table III. The gross appearance of fluid is helpful. The fluid is clear or straw colored in portal hypertension and hypo- albuminaemia and turbid when there is infection. In chylous ascites, the fluid in milky due to lymphatic obstruction. Haemorrhagic effusion is seen in malignancy, tuberculosis, pancreatitis and recent abdominal tapping.

Table III. Tests of ascetic fluid

Cell Count and Cytology Normal ascetic fluid contains fewer than 500 leukocytes / cmm and fewer than 250 polymorpho-nuclear leukocytes / cmm. The WBC count is elevated in all inflammatory condition and malignant ascites. Bacterial Infection is suspected when there is predominance of neutrophils with Serum Protein absolute neutrophil count > 250 per cmm. In tubercular Traditionally, the ascetic fluid is classified as transudate and malignant ascites lymphocytes usually predominate. or exudate. If the total protein content of the fluid is Malignant cells may be seen in ascites due to malignancy. more than 2.5gm per dl it is called as exudate as seen in cases of tuberculosis, malignancy and pancreatitis. In Culture and Gram Stain portal hypertension and hypo-albuminaemia the fluid is The tests are useful in isolating the bacteria in secondary a transudate with the protein content of less than 2.5gm peritonitis due to gut perforation but only 10% sensitive in Medicine Update-2011 387 detecting bacteria in spontaneous bacterial peritonitis (SBP) may detect as little as 100ml of intra-peritoneal fluid¹. by Gram stain5. In tubercular peritonitis AFB is rarely seen It also detects , pancreatic psuedocyst, and yield of culture of mycobacteria is low. intra-abdominal tumors, thickening of the mesentery and bowel wall, matting of the bowel loops and mesenteric Other Tests lympadenopathy. CT and MRI may provide information which Ascetic fluid glucose is lower in tubercular and malignant is not detected by Ultra-sonography. Doppler sonography can ascites. Ascetic fluid amylase is increased in pancreatic detect thrombosis of portal and hepatic veins. ascites. Sudan stained fat globules are seen in chylous ascites along with increased triglyceride content. Laparoscopy Direct visualisations of peritoneum and other organs by Imaging laparoscopy may be needed if the diagnosis is unclear. Even Chest X-Ray, Ultra-Sonography, CT & MRI Abdomen, are used the biopsies may be taken for a definite diagnosis. in the diagnosis of ascites. Abdominal ultra-sonography

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