Background: Dengue fever is a disease spread by the Aedes aegypti mosquito and is caused by one of four dengue viruses. This mosquito is a tropical and subtropical species widely distributed around the world. Dengue is characterized by leucopenia followed by thrombocytopenia. In general, dengue is a self-limiting acute febrile illness followed by a phase of critical defervescence, in which patients may improve or progress to a severe form. The main aim of this article is to diagnose dengue fever by combining sonography findings & thrombocytopenia. Materials and Methods: This is a retrospective study of 56 patients who were serologically diagnosed as having dengue fever.  Patients of both sexes with age 35±10 years admitted with fever and found to have thrombocytopenia are included in the study. Data were collected after obtaining consent in due format. Data are collected by using interview, physical examination, sputum examination, and laboratory finding including platelet counts, Dengue NS1 antigen test,  Dengue antibody IgG, IgM and Liver function test and patients were also referred for ultrasound scanning of the abdomen and thorax and the imaging findings were analyzed. Result: Out of 56 seropositive dengue cases, 31 (55%) patients showed edematous gallbladder wall thickening, 33 (59%) patients showed ascites, 25 (45%) patients had pleural effusion, 9 (17%) patients had hepatomegaly, 8 (14%) patients had splenomegaly and in 11 (19%) patients ultrasound findings were normal. Gall bladder wall edema was more commonly seen in patients with lower platelet counts. 22(40%) had platelet counts between 51,000 and 1 lakh. Majority of the cases with severe thrombocytopenia presented with DF with or without warning signs. Conclusion: Sonography findings & thrombocytopenia are reliable, rapid, cost-effective, easily available criteria for diagnosis of dengue fever with very high probability thus help in identifying patients for immediate admission,  monitoring & aggressive management to prevent development of hypovolemic shock& its complications. 
Keywords: Dengue Fever (DF), Platelet count, Thrombocytopenia, Ascites, hepatomegaly, splenomegaly, ultrasound.