Semirigid instrument which we compare was autoclavable Olympus LTF-160 (Olympus Tokyo, Japan). Handle and its controls were similar to flexible fiberoptic bronchoscope, with the insertion portion composed of 22 cm long rigid part and distal 5 cm flexible tip with angulation range 1600 up / 1300 down. The external diameter of insertion portion was 7 mm with 2,8 mm inner channel diameter. The instrument was compatible with Olympus EVIS Exera 160 and 145 and EVIS 100 and 140 video processors and light sources, otherwise employed in video-bronchoscopy. Forceps, which we used was flexible FB-55CD-1 Olympus forceps with 5 mm long cusps and diameter, which fitted the diameter of inner channel of semirigid thoracoscope.

The rigid instrument was autoclavable OP EndoEYE WA50120A (Olympus Tokyo, Japan) video thoracoscope. The length of the instrument was 29 cm with 00 direction of view and 700 field of view. The external diameter of the instrument was 10 mm with 5,2 mm inner channel diameter. The instrument was compatible with Olympus Visera OTV-S7V and EVIS Exera II CV-180 video processors. Cusps of rigid forceps had outer diameter 5 mm and length 10 mm.

thoracoscopy with semirigid instrument

• comparison of diagnostic adequacy of both instruments (number of definitive diagnosis in each group)
• size of the biopsy specimens in mm2
• interpretability of biopsy specimens in histopathology terms: 1. easily interpretable (enough tissue with all elements required for diagnosis) 2. interpretable with some difficulty (less tissue or diagnostic elements - diagnosis less reliable) 3. interpretable with great difficulty (little tissue or scarce diagnostic elements - low reliability of diagnosis) 4. non-interpretable (diagnosis not possible)

Major adverse events:

• bleeding
• infection
• reexpansion pulmonary edema

Minor adverse events:

• transient self-limited fever

• pain

• prolongued air leak

• subcutaneous emphysema

  30-day mortality