There are many factors that can affect the diagnostic yield of EUS-FNA, including lesion factors, the endoscoist experience, the needle size, the number of needle passes, and the suction technique. since diagnostic efficacy of different suction techniques for EUS-FNB is still uncertain, thus we decided to compare the diagnostic efficacy of three common methods: the 10 ml standard negative pressure, slow pull and wet suction.

the standard suction: after the needle is inserted in the mass, removing the stylet before performing EUS-FNA. Then attach a 10mL syringe to the end of needle. 20 times of for-backward Suction was applied after the lesion was punctured.

slow-pull : after the needle is inserted in the mass, slowly pull the stylet out while performing EUS-FNA with 20 times for-backward.

wet suction: after removing the stylet, the needle was flushed with 5mL of saline solution to replace the column of air with saline. A 10mL syringe was attached to the end of the needle. 20 times of for-backward Suction was applied after the lesion was punctured.

Inclusion Criteria:

1. age 18-75 years,male or female
2. diagnosis or suspection of solid pancreatic mass based on previous imaging examination (ultrasonography, CT or MRI)
3. lesion diameter larger than 1 cm
4. signed informed consent letter

Exclusion Criteria:

1. pregnant female
2. Pancreatic cystic lesions
3. Anticoagulant/antiplatelet therapy cannot be suspended
4. unable or refuse to provide informed consent
5. Coagulopathy (platelet count < 50× 103/μL,international normalized ratio > 1.5)
6. Severe cardiopulmonary dysfunction that cannot tolerate intravenous anesthesia
7. with history of mental disease
8. other medical conditions that are not suitable for EUS-FNB