Endoscopic ultrasound-guided fine needle aspiration: predictive factors of accurate diagnosis and cost-minimization analysis of on-site pathologist.

AIMS To evaluate a) new diagnoses by endoscopic ultrasound guided real-time fine-needle aspiration (EUS-FNA) compared with EUS alone; b) the predictive factors for an accurate EUS-FNA diagnosis, and c) the cost-effectiveness of the presence of an on-site cytopathologist. PATIENTS AND METHODS Demographic data, ultrasonographic characteristics, technical information on EUS-FNA and cytological results were prospectively collected in 213 patients. The gold standard used was pathological examination or clinical follow-up. Operating characteristics of EUS-FNA, multivariate analysis, and a cost-minimization study of on-site evaluation were performed with these variables. RESULTS Samples were obtained from a total of 262 lesions: extramural masses (n = 115), lymph nodes (n = 96), cysts (n = 40) and intramural lesions (n = 11). The overall accuracy of EUS-FNA was 89% (234/262 lesions). The accuracy of EUS in discriminating between malignant and benign disease was 92% but 105 lesions (40% of the total) were classified as indeterminate. The addition of FNA to EUS allowed almost all lesions (89%) to be diagnosed with an accuracy of 90%. The only variable independently associated with an incorrect diagnosis was intramural location of the target lesion. The effectiveness of EUS-FNA in the complete series progressively increased, reaching a plateau in the fourth pass. The presence of an attendant cytopathologist was cost-effective. CONCLUSIONS EUS-FNA allows diagnosis of most lesions classified as indeterminate by EUS alone. The only factor independently associated with low accuracy is intramural location of the lesion. The availability of an on-site cytopathologist is cost-effective.