Wet Heparinized Suction: A Novel Technique to Enhance Tissue Acquisition for Endoscopic Ultrasound Guided Fine Needle Biopsy (EUS-FNB) of Solid Abdominal Masses: A Randomized Prospective Trial

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.