Tritha Man Shrestha

1 Introduction Pleural effusion is defined as a collection of fluid in the pleural space due to increased production or impaired lymphatic absorption [1, 2]. The estimated prevalence of pleural effusion is 320 cases per 100 000 people in industrialized countries, with a distribution of etiologies related to most underlying diseases [3]. Approximately 1.5 million patients experience pleural effusion annually in the United States [4]. However, this prevalence is much higher in the developing world.