The aim of this study is to compare the diagnostic yield of intermittent versus continuous suction in the diagnosis of pancreatic solid lesions.

Solid lesions of the pancreas can be neoplastic or non neoplastic and it is important to accurately differentiate between them because of the poor prognosis related to pancreatic neoplasm. There are many types of solid pancreatic lesions: pancreatic adenocarcinoma, neuroendocrine tumor, lymphoma, solid pseudopapillary neoplasm and pancreatic metastasis.

There are several diagnostic methods for the study of pancreatic solid lesions. The different imaging test allow detection and characterization of those lesions, but most times an anatomopathological diagnosis is needed before stablishing the most appropriate treatment.

Endoscopic Ultrasound guided fine needle aspiration (EUS-FNA) is the diagnostic method of choice for the diagnosis of these lesions as it detects small lesions that sometimes cannot be found in radiological imaging test, evaluates vascular invasion and the presence of liver metastasis, and allows pancreatic puncture for a cytological diagnosis. EUS-FNA is the safest technique for pancreatic puncture and the least related to needle track seeding.

In order to gather as much material as possible different techniques have been proposed:

• Fanning technique and multiple pass technique: to guide the needle into different regions of the target lesions with or without removing the needle out of the lesion depending on wether the lesion is hard or soft.
• Use of stylet: there are no data clearly demonstrating that the use of suction increases the yield of EUS-FNA. Some authors do slow withdrawal of the stylet.
• Size of the needle: 19 gauge, 22 gauge, 25 gauge, depending on the localization, size and vascularization. There is increasing evidence that smaller needles offer at least similar results in diagnostic yield compared to larger needles and are also easier to manipulate.
• Use of suction: there is conflicting evidence in this point. Several studies have evaluated the use of high volume aspiration vs low volume aspiration, continous aspiration vs no aspiration and suction with empty syringe vs water-filled syringe but none is clearly better than other.

The investigators aim is to evaluate if the use of intermittent suction improves the diagnostic yield of pancreatic lesions compared to standard (continuous) suction. Up to our knowledge this method has not been yet evaluated.

Inclusion Criteria:

• Pancreatic solid lesion
• Patients over 18 years old
• Suitable for endoscopy

Exclusion Criteria:

• Contraindication for endoscopy
• Active anticoagulant therapy
• Thrombocytopenia or coagulopathy in the absence of its correction prior to the procedure
• Absence of informed consent
• Pregnancy
• Not accessible lesion for endoscopic ultrasound puncture