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.
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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)