Usefulness of Ascitic Fluid Cholesterol and Protein in the Differential Diagnosis of Ascites in Nigeria: Comparison with Conventional Cytology

Aim: This study was done to assess and evaluate the diagnostic accuracy of cholesterol and protein in differentiating ascites into malignant and non-malignant group in comparison with cytology.
Study Design: A cross sectional study to determine the correlation between ascitic fluid cholesterol and protein and malignant and non-malignant ascites.
Place and Duration of Study: This study was carried out at the clinics of gastroenterology, surgery, and obstetrics/gynecology at the Lagos University Teaching Hospital (LUTH), between August 2011 and July 2013.
Methodology: A total of 75 consecutive patients of Nigerian origin with ascites (37 malignant and 38 non-malignant) were studied for total cholesterol and total protein concentration in ascites. Also, cytology was done for all the 75 samples of ascitic fluid. Statistical analyses were carried out using SPSS software (version 15.0), and the level of significance set at p<0.05 and p<0.001.
Results: The ascitic fluid cholesterol and protein levels in malignant ascites were higher (values of 103.10±30.00 mg/dL for cholesterol and 38.72±18.00 g/L for protein respectively) than in non-malignant ascites (values of 33.20±22.00 mg/dL for cholesterol and 30.21±15.00 g/L for protein). The p value for cholesterol was less than 0.001. Cytology had sensitivity, specificity, positive predictive value, negative predictive value and overall diagnostic accuracy of 56.8%, 100%, 100%, 70.4%, and 78.6% respectively. Using a cut-off limit of 72.7 mg/dL, cholesterol had sensitivity, specificity, positive predictive value, negative predictive value and overall diagnostic accuracy of 94.6%, 94.7%, 94.6%, 94.7% and 94.7% respectively. Ascitic fluid total protein had sensitivity, specificity, positive predictive value, negative predictive value and overall diagnostic accuracy of 37.8%, 86.8%, 73.7%, 58.9%, and 62.7% respectively. Cholesterol was more sensitive than protein and cytology in the differentiating malignant from non-malignant ascites.
Conclusion: It was concluded that measurement of cholesterol in ascitic fluid can differentiate between malignant and non-malignant ascites, and can supplement cytology in the differential diagnosis of ascites.