Among the most common respiratory illnesses encountered in day-to-day clinical practice are undiagnosed exudative pleural effusions. Thoracentesis is usually the first diagnostic procedure performed to identify the etiology of these effusions. Although etiologies vary from country to country, malignant diseases, tuberculosis and empyema remain the most commonly encountered causes for exudative pleural effusions. Unfortunately, 40% of patients with malignant pleural effusions remain undiagnosed after a routine cytological examination of the pleural fluid and TB culture is positive in only 20% of TPE [
6,
7]. Blind pleural biopsy using Abrams needle is easy to perform, safe, and inexpensive. Although the value of closed needle biopsy in malignant pleural effusions is still a matter of controversy, it has a high yield (up to 80%) in TPE particularly when combined with pleural fluid TB culture. This has been attributed to the diffuse pattern in which TB affects the pleura. Hence, closed needle biopsy remains an important diagnostic tool in countries where the pre-test probability of TB is high and has been recommended as the initial diagnostic modality in these areas [
8‐
12]. Despite being more expensive than blind pleural biopsy, MT is becoming the standard diagnostic modality for undiagnosed exudative pleural effusions in developed and some developing countries as it enables direct visualization of the pleural space. Different studies from many countries have confirmed the high yield of MT in diagnosing exudative pleural effusions that exceeds 70% and can reach as high as 95% in malignant effusions and 99% in TPE [
9,
13‐
16]. Taking into consideration the high prevalence of TPE in the study subjects, the diagnostic yield of MT in the current study is lower than what was anticipated. One explanation for the relatively lower yield in Qatar is the low threshold of performing MT for cases with extensive pleural adhesions (due to non-visualization) which has resulted in the finding of non-specific fibrinous pleuritis in as high as 17% of cases (Table
4). Furthermore, the number of thoracoscopic biopsies (2-4 biopsies) performed at Hamad General Hospital per case is lower than the international recommendation and may be a contributor to the low diagnostic yield [
12,
17]. Two striking findings have been observed in the current study. The first was the very high percentage of TPE (as compared to malignant effusions) diagnosed by MT in Qatar (84.5% vs. 5.4%). This finding has not been observed in previous studies from other countries including those with high TB prevalence [
16,
18]. The other striking finding was the young age of patients with undiagnosed exudative pleural effusions who underwent MT. There are 3 plausible reasons for these findings; firstly, people below the age of 45 years constituted 85% of the total population in Qatar. Labor force from countries with high TB prevalence constitutes a significant proportion of such young population as well as 97% of TB cases encountered in this country [
19]. In contrast to pleural TB in developed countries, Ibrahim, et al. in a previous study of pleural TB in Qatar found that younger age groups were the most commonly affected by the disease (84% are below the age of 45 years, with mean age of 31.5). Furthermore, the pleural involvement in most of the cases resulted from primary infection rather than reactivation of an old pulmonary TB [
7]. Secondly, in contrast to other developing countries where closed needle biopsy is the initial diagnostic consideration in suspected pleural TB, this procedure is very rarely performed nowadays in Qatar and has largely been replaced by MT. Moreover, owing to the highly effective and strict National TB Control Program in Qatar, there is usually emphasis on tissue or microbiologic diagnosis of TB in the country. The median length of stay (LOS) and duration of chest tube in the current study were 3 days and 1 day respectively. These findings are in agreement with international figures [
12]. Nevertheless, we believe that other factors (unrelated to the procedure) such as waiting for confirmatory histologic reports and the process of incorporating patient’s data in TB registry prior to discharge are important contributors to the LOS following MT in Qatar. Recently, it has become feasible in a number of countries to perform the procedure as a day-case [
10]. The current study was the first to document the experience with MT in this country with a young population. The results of this study can be generalized to the whole country as Hamad General Hospital is the only tertiary referral center performing MT in Qatar and receives referrals from other health care facilities in the country. Nevertheless, in addition to the limitations inherent in a retrospective study, an important limitation of this study is the lack of comparison between MT and closed needle biopsy with regard to diagnostic yield, safety and cost effectiveness particularly in cases with suspected TPE from this region. Furthermore the finding of a high percentage of nonspecific fibrinous pleuritis due to extensive adhesions has limited the yield of MT in the current study.