Background
/Aims: We performed a prospective study to compare the feasibility, safety and tolerance among ultrathin transnasal (UT-N), thin transnasal (T-N) and ultrathin oral (UT-O) esophagogastroduodenoscopy. Methods: Two narrow diameter endoscopes (Ø=5.2 mm for UT-N and UT-O, Ø=6.5 mm for T-N) were used. The operator factors and patient factors were quantified by a visual analogue scale. Results: The procedure was successfully completed in 100 of 100 patients in the UT-O group. The T-N group, when compared with the UT-N group, accounted for a significantly higher portion of failure (14% vs 3%, respectively, p=0.000), more cases of epistaxis (11% vs 3%, respecttively, p=0.013) and more complaints of nasal pain (17% vs 6%, p=0.016). The overall quality of the exam was significantly higher in the UT-N group (UT-N, 8.7; T-N, 8.1; UT-O, 8.2, p=0.04). The frequency of a incurring a gag reflex was significantly lower in the UT-N group (UT-N, 1.26; T-N, 1.48; UT-O, 2.94, p= 0.000). The patients' score for overall general satisfaction was higher in the UT-N group (UT-N, 8.5; T-N, 7.8; UT-O, 7.7, p=0.006). Nausea was significantly reduced the in UT-N group (UT-N, 8.2; T-N, 7.8; UT-O, 7.3, p= 0.003). Patients in the UT-N group were more willing to repeat the same procedure (UT-N, 82%; T-N, 65%; UT-O, 71%, p=0.046). Conclusions: Ultrathin transnasal endoscopy is more feasible, safe and comfortable compared with the thin transnasal endoscopy or when compared with either instrument that was passed orally. (Korean J Gastrointest Endosc 2008;36:329-335)