Negative predictive value of endoscopic ultrasound in patients referred for fine-needle aspiration

Endoscopic ultrasound (EUS) is a valuable diagnostic tool in pancreatic diseases and its high negative predictive value (NPV) in excluding malignancies is universally recognized. Moreover, EUS with fine-needle aspiration (EUS-FNA) can significantly impact on diagnosis and management of many clinical conditions. However, there are circumstances in which EUS-FNA cannot or should not be performed. We evaluated the factors that prevented us from performing or induced us not to perform FNA.

The study was conducted in a tertiary university hospital. A total of 211 patients suspected of having solid pancreatic malignancy on the basis of clinical presentation and computed tomography and/or magnetic resonance imaging was included. When FNA was withheld because not deemed necessary by the operator, the NPV of EUS was calculated.

In 9 patients (4.3% of the procedures), FNA was withheld because of contraindications that should have been foreseen by the referring physician. In 30 subjects, FNA was not accomplished as no lesions requiring biopsy were actually found at EUS exploration. In this group, EUS reached a NPV of 96.7% in excluding malignancy, but it reached 100% in patients without chronic pancreatitis.

In a cohort of patients with high pre-test probability of malignancy, the high NPV of EUS was confirmed. False negative results should be expected in patients with chronic pancreatitis and they need a strict follow-up.