Endoscopic ultrasonography-guided fine-needle aspiration biopsy: A safe method for accurate diagnosis

Endoscopic ultrasonography-guided fine-needle aspiration biopsy (EUS FNAB) is a relatively new technique for obtaining specimens with excellent imaging power. The convex type of echoendoscope used with EUS FNAB provides images perpendicular to the endoscope, which differ from those of popular radial echoendoscopes and, hence, require different usage techniques. Color flow imaging is used to avoid the vessels in and around the mass during puncturing. EUS FNAB for submucosal tumors is sometimes difficult because the needle slips easily, and the gastrointestinal wall tends to be stretched when pushing the needle, which can be solved by making a dimple on the wall before puncturing. Lesions of the pancreas head, especially those at the uncus, and lymph nodes near the superior mesenteric artery are also difficult because of their distance from the endoscope and the resultant bending of the needle. Tissue sampling is more successful when the angle between the endoscope and the needle is kept at just less than 45 degrees, as this helps to transmit the hand force to the needle effectively. The complication rate of EUS FNAB is reportedly 1-2%, and so the technique is considered a safe modality, except for cystic lesions of the pancreas. Recent histological evidence is needed before applying medical therapies, such as chemoradiation and surgery, especially when imaging modalities alone cannot supply the evidence of malignancy; hence increasing importance of EUS FNAB is expected.