Identifying factors that tend to influence diagnostic yield and complication rates of computed tomography guided fine needle aspiration cytology for diagnosing mediastinal and pulmonary lesions

Computed Tomography (CT) guided Fine Needle Aspiration Cytology (FNAC) for diagnosing mediastinal and pulmonary lesions is a procedure in which CT images are employed to precisely locate the lesion, measure its size, assess its distance from the skin surface and finally to decide the positioning of the patient and type of the needle to be used for the procedure. It is an advanced investigation modality employed for obtaining aspirates pulmonary lesions, either as a first-line diagnostic procedure, or following non-diagnostic bronchoscopy or sputum cytology. CT guidance allows performance of fine needle aspiration cytology in all such situations where ultrasound or conventional X-rays cannot correctly visualise the lesion or the needle tract. Obtaining a detailed cytopathological analysis report of the aspirate obtained upon FNAC is thus considered to be a dependable approach. Literature is replete with studies that have established the diagnostic accuracy of this procedure. the sensitivity reported to be as high as 76% to 97% while complication rates range from 5% to 61%. While it has been reported that sensitivity and specificity falls significantly if the lesion size is <2 cm and distance of the lesion from skin surface >5 cm. Other reports show that lesions 1.0 cm or smaller can yield good diagnostic accuracy rates as well. Pneumothorax and hemoptysis or pulmonary hemorrhage are reported to be the most common post-procedural complications encountered. Biopsy of central lesions, especially those in the mediastinum, have been found to be more often associated with pneumothorax, while lesions near the hilar region with hemorrhagic complications. The present study was carried out with an aim to identify the factors that tend to influence the diagnostic yield and complication rates of this procedure as performed at our hospital, to compare the diagnostic accuracy and complication rates of this procedure with previously documented studies and to assess the feasibility of carrying out this procedure in our hospital setting. This single-centre study on 200 patients incorporated a combined retrospective analysis of hospital records of 150 patients subjected to CT-guided FNAC for mediastinal or pulmonary lesions; and a prospective analysis on 50 patients over the period of 2 years. The overall accuracy of the procedure was found to be 92.5%. The overall sensitivity was found to be 94.03% while specificity was found to be 100% as there were no false positives. Out of the 200 patients who were evaluated in this study, 22 developed post-procedural complications. Thus, the complication rate as found in our study was 11%. From the results of the study we can conclude that advancing age, female sex, left sidedness of the lesion, prone positioning of the patient during procedure, do not lead to any increase in complication rates of CT guided FNAC All complications developed as a result of the procedure are not life threatening and can be easily managed on an in-patient basis. CT FNAC is a very safe and accurate procedure, thus it is totally feasible to carry it out on a regular basis in tertiary care hospital setting.