Forward-view Endoscopic Ultrasound: A Systematic Review of Diagnostic and Therapeutic Applications

Abstract

Endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) and therapeutic procedures have been performed by a curved linear array (CLA) echoendoscope since the early 1990's. This particular echoendoscope, allowing real time visualization of aspiration needles and of other devices, has substantially remained unchanged since its introduction to the market. In a context of rapidly expanding indications for EUS-guided procedures, a dedicated forward view (FV) echoendoscope has been developed and tested under different clinical conditions. The FV echoendoscope is equipped with front endoscopic and EUS view, allowing deployment of needles and other devices through the working channel in straight direction. Several new diagnostic and therapeutic applications may thereby potentially be feasible with the FV echoendoscope and the established ones may prove easier to accomplish. The published literature with the FV echoendoscope has been systematically reviewed and the results are presented analytically and discussed in detail. EUS-FNA and therapeutic procedures, including pancreatic pseudocyst drainage, treatment of gastric fundal varices, celiac plexus neurolysis, and duct drainage were reported. The FV echoendoscope showed some unique advantages, opening new possibilities such as EUS-FNA in difficult gastrointestinal tracts and combined endoscopic/EUS treatment with frontal approach. However, no statistically significant evidence of superiority of the FV echoendoscope vs. the CLA echoendoscope was found in pancreatic pseudocyst drainage. No complications specifically attributable to the use of the FV echoendoscope were reported.

Keywords: endoscopic ultrasonography; fine needle aspiration; forward view echoendoscope; forward viewing; linear echoendoscope.

Figure 1

Search results.

Figure 2

A: The linear echoendoscope in full retroflexion with maximal angulation of the elevator. Notice the maximal deflection of a 22-G needle. It is usually not smooth to advance a needle in this position. B: The FV echoendoscope in full retroflexion (no elevator in this scope). Notice the greater deflection of a 22-G needle compared to 3a. In this position the needle can be advanced quite smoothly.