The purpose of this research is to compare the amount and quality of tissue obtained by EUS-FNB when the device is flushed with an anticoagulant or "blood thinner" vs. saline a salt water solution as well as the use of a microsieve in order for the doctor to look at the tissue to check the acceptability of the specimens before sending for analysis.

You will be randomly assigned (like a flip of a coin) to have either the blood thinner or the salt water solution placed within the needle being used to sample your abdominal tumor and to have either a sieve used or not.

You will be one of 42 participants enrolled in this data collection study which includes 1 sites in the United States.

Since its inception in the early 1990's, endoscopic ultrasound with fine needle aspiration (EUS-FNA) has developed into an important method for obtaining diagnostically accuracy for gastrointestinal, and extra-luminal pathology [1,2]. Present society guidelines by both the European Society of Gastrointestinal Endoscopy (ESGE) and American Society of Gastrointestinal Endoscopy (ASGE) have estimated an overall 60-90% diagnostic accuracy of EUS-FNA [2,3]. However, this accuracy is dependent upon determination of adequacy by expert gastrointestinal pathologists, which may not be available at all centers [4-6].

New developments in needle technology has led to development of "core needles", which can allow for acquisition of a tissue specimen with intact tissue architecture and therefore more ability for immunohistochemical staining (IHC). When evaluating pancreatic lesions, FNB needles have demonstrated 81-100% technical success and up to 94.7% diagnostic accuracy [18-21]. Overall, EUS-FNB appears to be a promising addition to EUS guided tissue acquisition, which has the potential of leading to improved diagnostic accuracy.

As an additional means for optimizing EUS-FNB, heparin has been described and studied in the past. The study investigators have been using heparin to prime the wet suction needle to prevent formation of clot in the needle which produces "blood noodles" in the specimen that can interfere with tissue processing and interpretation. There are previous data demonstrating that heparin priming of the needle may also increase yield [22]. The study investigators have demonstrated that use of a heparin primed needle does not interfere with cytology, histology or immunohistochemical analysis, and may ease stylet handling [23]. Also, the study investigators have directly validated the use of heparin for EUS-guided liver biopsies (EUS-LB) demonstrating improvement in the size and number of histologic fragments obtained from EUS-guided biopsy [24-25]. Given this information, heparin flush is actively used and readily available, in EUS-guided biopsies here at UH.

Rapid onsite cytological evaluation (ROSE) has been used to make an immediate assessment of tissue adequacy during the EUS-FNA procedure, as well as to deliver a rapid pathological diagnosis during the EUS session. ROSE has been shown to increase the yield while having the potential of decreasing the number of needle passes required. However, ROSE is not available at many EUS centers. It would be advantageous to predict adequacy of a needle biopsy specimen without having to rely on ROSE.

In standard EUS-FNA practice, part of the biopsy specimens is used to prepare a smear that can be examined microscopically. The remainder of the specimen processed by the laboratory for "cell block" analysis. Microscopic examination of the smears and the cell-block are done by the pathologist to arrive at a final diagnosis.

The study investigators have developed a new technique of specimen enrichment using a "microsieve device". In this technique, a small microsieve collects the larger tissue fragments, while single cells and small cell clusters wash through the microsieve. Visible tissue fragments or cores likely represent a macroscopic representation of adequacy of tissue, and could theoretically supplant ROSE in providing an on-site determination of adequacy.

In the course of this study, the study investigators will collect the larger fragments as well as the wash-through and examine each separately.

Inclusion Criteria:

• Age ≥ 18 year
• Non-pregnant Patients
• Patients with the presence of a solid abdominal mass as seen on diagnostic imaging [ie. ultrasound (US), computer tomography (CT) or magnetic resonance imaging (MRI)] scheduled to undergo EUS examination OR Patients who underwent a prior EUS-FNA/FNB for solid pancreatic mass and did not receive a conclusive diagnosis
• Patients with platelet count > 50,000
• Patients with International Normalized Ratio (INR) < 1.5

Exclusion Criteria:

• Age < 18 years
• Pregnant Patients
• Patients who cannot consent for themselves
• Patients with anticoagulants or anti-platelet agents (excluding aspirin) within the last 7-10 days
• Patients with cystic abdominal masses
• Patients with a platelet count < 50,000
• Patients with an INR > 1.5
• Patients with a heparin or porcine allergy
• Patients with prior heparin induced thrombocytopenia (HIT)
• Patient's with religious aversion to porcine-containing products

These needle preparations will be wrapped in non-transparent 2-inch tape to hide the appearance of the injectate agent. The needle is prepared by removing the stylet and flushing with the selected substance. The PI/Co-I will then flush the needle with the selected substance until drops of the liquid are seen exiting the needle tip. Those randomized to have the needle flushed with heparin will be termed "dry heparin" and will be flushed with 500 U heparin USP per 10 mL. Those who randomize not to receive heparin, the needle will be flushed with saline. The device shall then be placed into the linear echoendoscope and the FNB will be performed. The PI is blinded to heparin vs. no heparin only. Randomization to the microsieve vs. not is apparent to the PI.