Objective. To review the indications and accuracy of diagnostic thorac
oscopy for pleural effusions of unknown origin. Design. Retrospective
review of consecutive patients referred for diagnostic thoracoscopy ov
er a B-year period from 1 January 1989 to 31 December 1993, Setting, T
ertiary referral cardiothoracic unit. Patients, Thirty-four patients r
eferred from either medical or oncology services within a university-a
ffiliated academic complex. Interventions. All patients had diagnostic
thoracoscopy performed under general anaesthesia. Retrospective data
were collected in respect of presenting symptoms, gross findings, fina
l pathological findings, amount of drainage, length of hospital stay a
nd complications of the procedure. In 7 patients (21%), iodised talc w
as insufflated at the same time to create pleurodesis. Main results. F
inal diagnoses were: 17 (50%) malignant disease, 6 (18%) tuberculosis
and 9 (26%) 'negative' pathology. In 2 (6%), further intervention was
required to make a conclusive diagnosis. The diagnostic sensitivity fo
r malignant disease was 89% and the specificity 100%, For pleural tube
rculosis both the sensitivity and specificity were 100%, For 'negative
' diagnoses the negative predictive value was 82%. A history of fever
and sweats had a marked association (P = 0.002) with the final diagnos
is of tuberculosis. No association could be identified between the gro
ss observations at the time of thoracoscopy and the final diagnosis. T
he average length of hospital stay was 6.7 (range 1 - 25) days. There
was 1 in-hospital death (3%), and 9 patients (26%) had major complicat
ions related to the procedure. Conclusions. Diagnostic thoracoscopy is
a useful modality for obtaining a diagnosis in effusions of unknown o
rigin where other methods have failed. The presence of symptoms such a
s fever and sweats is highly associated with a final diagnosis of tube
rculosis.