Comparison of capillary versus aspiration technique in endoscopic ultrasound-guided fine-needle aspiration: A preliminary report.

Introduction: Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is widely used to diagnose pancreatic malignancies. Different EUS-FNA techniques have been described to improve sample quality. Recently, a new technique, using capillarity, has been proposed.

Aim: To assess the quality of cytological samples, comparing two different FNA techniques, in order to optimize tissue acquisition.

Methods: All consecutive patients with solid pancreatic lesions, requiring an EUS-FNA, were included in the study between July and September 2013. All procedures were done under deep sedation. FNA was performed using a 25 gauge needle, using both capillary and aspiration technique. Patients were randomized to undergo firstly one or the other technique. Samples were evaluated "on site" by expert cytotechnologist. An expert cytopathologist, blinded for the technique used, reviewed the slides, for final diagnosis and assessed sampling quality. Quality of samples was evaluated through the assessment of the amount of blood, cellularity, tumoral versus normal cells ratio and adequacy for final diagnosis. Data were analyzed with Student's t-test and Chi-square test, assuming a significant P value of 0.05.

Results: A total of 30 consecutive patients (19 M, mean age 67.8 years) with an EUS finding of pancreatic solid lesion were included in the study. Cytological final diagnosis was adenocarcinoma in 25/30 (83.3%) cases, neuroendocrine tumor 1/30 (3.3%), intraductal papillary mucosal neoplasms with high-grade dysplasia 2/30 (6.7%), gastrointestinal stromal tumor in 1/30 (3.3%) and negative for malignant cells 1/30 (3.3%). The difference between the overall blood amount score per technique was not statistically significant (P = 0.61) as well as the cellularity score (P = 0.08). In 13/30 patients (43%) the two techniques reported concordant T/N ratio. In 6/30 patients (20%) final diagnosis was achieved only by capillary obtained smears. In 1/30 patients (3.3%) the diagnosis was done with aspiration. In the remnant, the ratio between the two techniques was similar. Adequacy was reached in 24/30 (80%) with aspiration and 29/30 (97%) with capillary technique (P = 0.04).

Conclusions: Aspiration and capillary sampling techniques provided similar results in cellularity and blood amount. However, adequacy rate was significantly superior in capillary technique. Furthermore, in 20% of cases, final diagnosis was achieved only with capillary samples.