Why you do or do not need thoracoscopy

European Respiratory Review, Sep 2010

Thoracoscopy is an old but still very valuable technique for the evaluation of pleural pathology and, especially for the further investigation of the aetiology of pleural fluid. It remains of great importance, since it is able to not only provide an exact diagnosis, but also can have therapeutic potential. In this review, the differential diagnostic aspects of transudate versus exudate are further elaborated, and the role of thoracoscopy is compared to closed pleural biopsy and image guided biopsy.

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Why you do or do not need thoracoscopy

J.P. Janssen Thoracoscopy is an old but still very valuable technique for the evaluation of pleural pathology and, especially for the further investigation of the aetiology of pleural fluid. It remains of great importance, since it is able to not only provide an exact diagnosis, but also can have therapeutic potential. In this review, the differential diagnostic aspects of transudate versus exudate are further elaborated, and the role of thoracoscopy is compared to closed pleural biopsy and image guided biopsy. - If the protein level is .35 g?L-1, the effusion is most likely an exudate [2]. In borderline exudates (protein level .25 but ,35 g?L-1) Lights criteria may misclassify transudates in up to 20% of cases, especially in patients with congestive heart failure who have been on diuretics. To discriminate true transudates from pseudo-exudates, measurement of the pleural protein gradient or the pleural fluid albumin gradient can be applied: if serum protein level minus pleural protein level is .3.1 g?dL-1, or serum albumin level minus pleural albumin level is .1.2 g?dL-1, it is a transudate [1]. In recent studies, measurement of pro-B-type natriuretic peptide (pro-BNP) in pleural fluid and serum appeared to be promising in the diagnosis of transudates in patients with chronic heart failure. In case of possible misclassification by the use of Lights criteria, measurement of pro-BNP level may appear to be a better tool to differentiate a transudate from a pseudo-exudate [36]. In the case of an exudate, and benign or nonconclusive cytology, infection, pulmonary embolism and abdominal disease should be considered. If these diseases have been ruled out or are very unlikely, the exudate is caused by malignant disease, tuberculosis or the exudate is idiopathic. In the past, it has been stated that a malignant pleural effusion can also occur as a transudate [7]. This is most likely due to imperfect application of the diagnostic rules, or comorbid conditions like hypoalbuminaemia, cirrhosis with ascites or chronic heart failure. ANALYSIS OF AN EXUDATE In the case of a proven exudate with nonconclusive cytology after (repeated) thoracocenthesis, an additional procedure to obtain pleural histology tissue is the next step. This can be done with a minimal invasive procedure in four ways: closed pleural biopsy (CPB; Abrams biopsy), thoracoscopy, ultrasound (US)-guided biopsy, and computed tomography (CT)-guided biopsy. A comparison of these techniques is summarised in table 1. CPB (ABRAMS BIOPSY) CPB is an old technique. In patients with pleural effusion, a blind biopsy of the parietal pleura can Ultrasoundguided biopsy be obtained. In malignant pleural disease, the additional diagnostic yield of CPB after thoracocenthesis is limited to 7% [8]. The diagnostic yield of CPB is better in areas with high incidence of tuberculosis (TB), as has been demonstrated by DIACON et al. [9]. In their study, the diagnostic yield of the combination of TB culture and histology reached 79%, with a sensitivity of 93%, if combined with serum adenosine deaminase level and lymphocytosis of the pleural fluid (lymphocytes/neutrophils .0.75). In a prospective study in the UK, MASKELL et al. [10] compared CPB with CT-guided pleural biopsy. The results for the CT group were: sensitivity 87%, specificity 100% and negative predictive value 80%. In the CPB group the results were: sensitivity 47%, specificity 100% and negative predictive value 44%. Comparison of techniques to obtain pleural biopsy Closed pleural biopsy Blind procedure Low diagnostic yield# #: diagnostic yield is higher in areas with endemic tuberculosis. Ultrasound-guided biopsy First author [ref.] First author [ref.] The diagnostic yield of thoracoscopy Diagnostic yield % False negative cases of NSP during follow-up Data are presented as n (%), unless otherwise stated. NSP: nonspecific pleuritis; NS: not stated. In conclusion, CPB should no longer be used in a setting where image-guided pleural biopsies can be obtained. Use of CPB is only indicated in areas with high incidence of TB and limited medical resources [9]. CT- VERSUS US-GUIDED PLEURAL BIOPSY There are no comparative studies of the diagnostic yield of CTand US-guided biopsy; the diagnostic sensitivity of both techniques is high (.83%) [11]. The characteristics of each procedure are summarised in table 1. THORACOSCOPY VERSUS IMAGE-GUIDED PROCEDURES The diagnostic yield of thoracoscopy is high; it is reported to be .90% in the majority of studies (table 2). Although it is a more invasive procedure compared with image-guided pleural biopsy, the big advantage of thoracoscopy is the possibility to perform a therapeutic intervention in the same session as the diagnostic biopsy of the pleura. The possible therapeutic procedures during thoracoscopy are: 1) removal of (septated) pleural effusions; 2) talc poudrage (under visual control if preferred); and 3) drain positioning under visual control. Thoracoscopy (...truncated)


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J.P. Janssen. Why you do or do not need thoracoscopy, European Respiratory Review, 2010, pp. 213-216, 19/117, DOI: 10.1183/09059180.00005410