After patients have been screened and have signed informed consent, they will be taken to the endoscopy suite. Once the decision has been made to proceed with Fine Needle Aspiration (FNA), the subject will be randomized to 1 of 4 groups:

• 22 gauge (G) needle with suction
• 25 G needle with suction
• 22 G needle without suction
• 25 G needle without suction

Follow-up Phone Call Phase:

Unit staff will call patients 1 week after the procedure to check if patients had any adverse events from the procedure and this will be recorded onto the dataset.

All adult patients referred to Florida Hospital for evaluation of a pancreatic mass lesion will be eligible for entry into the study. Patients will be approached at the time of procedural consent for the study.

1. After written informed consent is taken, Endoscopic Ultrasound (EUS) will be performed under conscious sedation.
2. At the time of EUS, patients who require FNA will be randomized to the two needles (22 G or 25 G needles) and to the two techniques (using suction or not using suction).
3. Computer-generated randomization assignments using the block randomization method will be obtained from the statistician prior to study enrollment. These will be placed in sequentially numbered sealed opaque envelopes and opened by the endoscopy nurse immediately after the decision to perform FNA is made. The randomization sequence will specify the needle size to be used and whether or not suction will be applied for FNA.
4. FNA will be performed in the standard fashion using one of the designated needle sizes (using the fanning technique to pass the needle 12-16 times into the lesion) by one of the experienced endosonographers in the unit. The needle stylet will be left in place for the first pass and then removed for subsequent passes. Suction will be applied during aspiration of the mass as dictated by the randomization sequence.
5. First two passes will be performed to obtain tissue sample for cell block analysis. Therefore, the tissue obtained with the first and second passes will be expressed onto a slide and into test tubes for cell block analysis.
6. From the third pass onwards, the aspirate obtained will be examined onsite by the cytopathologist, who will be available to interpret the slides immediately to determine diagnostic adequacy of the sample per standard practice. Once the diagnosis is made and the adequacy of the sample is affirmed by the cytopathologist, the procedure will be stopped and the echoendoscope will be withdrawn from the patient.
7. Total number of passes to obtain a diagnostic cytological aspirate made will be recorded at the time of procedure, as well as the occurrence of needle dysfunction, technical failure, and any immediate complications.
8. The samples taken will be transported to the pathology lab (per standard practice) where the cellular aspirate and cell block samples will be evaluated by the pathologist. 10% of samples from each subgroup (i.e. 22G with suction, 22G without suction, 25G with suction, 25G without suction) will be further analyzed for the presence of molecular markers for malignancy.
9. After the appropriate observations are deemed satisfactory, patients will be discharged as per unit policy.
10. Unit staff will call patients 1 week after the procedure to check if patients had any adverse events from the procedure and this will be recorded onto the dataset.

Inclusion Criteria:

1. All patients referred to Florida Hospital Endoscopy Unit for assessment of pancreatic mass lesions that require FNA
2. Age ≥ 19 years

Exclusion Criteria:

1. Age <19 years
2. Unable to safely undergo EUS for any reason
3. Coagulopathy (INR >1.6, Thrombocytopenia with platelet count <80,000/ml)
4. Unable to provide consent for any reason
5. Pregnancy (confirmed with Standard of Care urine pregnancy test for all women with child-bearing potential)

There is no plan to share Individual Participant Data.