Intragastric Pressure Required to Achieve Strong Extension of the Gastric Wall for Invasion Depth Assessment in Early Gastric Cancer: A Single-Center Prospective Observational Study.

Background and Aims: Previously, we developed a simple and accurate method to measure intragastric pressure (IP) using upper gastrointestinal endoscopy. This study prospectively characterized the IP at the first point of visually defined strong extension of the gastric wall and evaluated the diagnostic performance of the non-extension sign (NES) for assessing invasion depth in early gastric cancer (EGC). Methods: This was a single-center prospective study. Consecutive patients with EGC scheduled for upper gastrointestinal endoscopy were enrolled. The patients underwent continued air insufflation until strong extension of the gastric wall occurred, at which point the IP was measured. Endoscopic assessment of invasion depth was then performed using the NES. Results: Forty-six patients were enrolled; however, three were excluded, resulting in 43 patients included in the analysis. IP at the first point of strong extension of the gastric wall ranged from 5 to 20 mmHg; therefore, strong extension was achieved at an IP of 20 mmHg or less in all 43 patients. For the endoscopic diagnosis of the depth of invasion in EGC using the NES, this yielded a sensitivity of 80% (95% confidence interval (CI), 37.6%-96.4%), a specificity of 100% (95% CI, 90.8%-100%), and a diagnostic accuracy of 98% (95% CI, 87.9-99.6). No procedure-related adverse events were observed. Conclusions: IP at the first point of visually defined strong extension of the gastric wall ranged from 5 to 20 mmHg among technically evaluable patients. NES assessment showed high specificity and diagnostic accuracy, with no adverse events observed.