Diagnostic Value and Effective Factors on Transbronchial Lung Biopsy Using Cup and Alligator Forceps

Lung biopsy through the airways by using a flexible bronchoscope (transbronchial lung biopsy: TBLB) is a suitable method for obtaining tissue specimens. This study aimed at evaluating the factors influencing TBLB results in order to increase the diagnostic power of this method.
This was a prospective double blind observational study. We had a total of 44 patients with pulmonary lesions who underwent biopsy and 4 specimens were obtained from each patient. A total of 176 specimens were obtained from all patients. Biopsy specimens were taken using cup and alligator forceps alternatively. Characteristics of the obtained specimens including size, floatation, alveolarity, and bleeding were thoroughly studied. After sending to the pathologist, specimens were divided into 2 groups of diagnostic and non-diagnostic specimens.
Of a total of 176 specimens, 37 (21%) were diagnostic and 139 (79%) were non-diagnostic. From 88 specimens obtained by the alligator forceps, 16 were diagnostic while from the same number of specimens taken by the cup forceps 21 had diagnostic value. However, this difference was not statistically significant (P>0.05). Of the small specimens (57 cases), 12 (21.1%) were diagnostic while among the 66 medium specimens, 12 (18.2%) and from the 53 large specimens, 13 (24.5%) were diagnostic. No statistically significant difference was detected in this respect (P>0.05). Among specimens floating on the surface of the liquid (48 cases), 6 (12.5%) had diagnostic value. Of the 12 specimens suspended in the liquid, 2 (16.7%) and among the 116 specimens precipitated at the bottom, 29 (25%) were diagnostic. These differences were not significant either (P>0.05). Of the 84 specimens with more than 20 alveoli, 31 (36.9%) were diagnostic. Among 26 specimens with less than 20 alveoli 5 (19.2%) were diagnostic. This correlation was statistically significant indicating that the higher the number of alveoli in the biopsy specimen, the greater the chance of being diagnostic.
This study failed to find a significant correlation between the diagnostic power of TBLB and type of forceps, sample size or floatation of the specimen in the liquid. However, number of alveoli present in the tissue specimens was significantly correlated with its diagnostic value. Increasing the number of specimens to four can increase the chance of diagnosis.