Endoscopic ultrasound guided fine needle aspiration (EUS-FNA) and fine needle biopsy (EUS-FNB) are well established techniques for the acquisition of tissue to classify a number of lesions of the gastrointestinal tract and surrounding organs. These include pancreatic, lymphoid, subepithelial and other abdominal lesions. Historically, FNA was the sole available modality used to obtain cytological samples for analysis. The major shortcoming of this technique is the lack of a histological tissue core.

In recent years attention has turned to optimizing needle design to improve sample quality. New needles have been developed which aim to obtain a core of tissue with preserved architecture.

These needles include the first generation Reverse-bevel Echo Tip® HD ProCore™ (Wilson-Cook Medical Inc., Winston-Salem, NC, United States), and the second generation Fork-tip SharkCore™ (Medtronic Inc., Sunnyvale, CA, United States) and Franseen Acquire™ (Boston Scientific, Marlborough, MA, United States).

Currently there are a paucity of studies comparing the performance of these needles, and only two of these are prospective randomized controlled trials. Real world performance of these needles has seldom been reported, with only one RCT including non-pancreatic masses in their analysis.

The investigators hypothesize that second generation needles have equivalent or better diagnostic performance than the prior first-generation needle.

To test this, the investigators aim to conduct a prospective randomized controlled study comparing the performance of Fork-tip and Franseen needles for the sampling of pancreatic, subepithelial, lymphoid and other abdominal or mediastinal lesions. They also aim to include a retrospective control arm of consecutive cases using the first-generation Reverse-bevel needle.

The investigatora aim to assess the diagnostic yield of each needle, as well as number of needle passes used, and specimen quality.

Inclusion Criteria:

• Any solid tissue biopsy performed at the time of endoscopic ultrasound

Exclusion Criteria:

• Fluid samples were excluded.
• Cases where biopsy was not deemed necessary by the proceduralist based on endosonographic findings
• Cases where biopsy was deemed unsafe