内窥镜下黏膜下剥离术(ESD)治疗早期胃癌(EGC)能保存整个胃，但遗漏的胃癌(MGCs)经常在剩余的胃和黏膜中被发现。然而，造成MGCs的内镜原因仍不清楚。因此，我们旨在阐明ESD后MGCs的内镜原因和特征。从2009年1月至2018年12月，我们收集了所有接受ESD治疗的初诊EGC患者。根据ESD术前食管胃十二指肠镜检查(EGD)图像的回顾，我们确定了每种内镜原因(perceptual、exposure、sampling errors和inadequate preparation)和MGC的特征。总共分析了2208名接受ESD治疗的EGC患者。其中，82名(3.7%)患者有100个MGCs。MGCs的内镜原因分别为：69例(69%)感知误差，23例(23%)曝光误差，7例(7%)采样误差和1例(1%)缺乏准备。逻辑回归分析表明，感知误差的风险因素包括男性(Odds比[OR]为2.45；95%置信区间[CI]为1.16-5.18)、等色性染色(OR为3.17；95% CI为1.47-6.84)、大弯度(OR为2.31；95% CI为1.121-4.40)和病变大小≤12 mm(OR为1.74；95% CI为1.07-2.84)。曝光误差的位置分别为陈旧性角、胃体后壁和幽门区。我们确定了四种MGC，并阐明了其特征。改善ESD前的EGD观察质量，关注感知误差和曝光误差的风险，可能有助于防止漏诊EGCs。

As endoscopic submucosal dissection (ESD) for early gastric cancer (EGC) preserves the entire stomach, missed gastric cancers (MGCs) are often found in the remaining gastric mucosa. However, the endoscopic causes of MGCs remains unclear. Therefore, we aimed to elucidate the endoscopic causes and characteristics of MGCs after ESD.From January 2009 to December 2018, all patients with ESD for initially detected EGC were enrolled. According to a review of esophagogastroduodenoscopy (EGD) images before ESD, we identified the endoscopic causes (perceptual, exposure, sampling errors, and inadequate preparation) and characteristics of MGC in each endoscopic cause.In total, 2208 patients who underwent ESD for initial EGC were analyzed. Of these, 82 (3.7%) patients had 100 MGCs. The breakdown of the endoscopic causes of MGCs was as follows: 69 (69%) perceptual errors, 23 (23%) exposure errors, 7 (7%) sampling errors, and 1 (1%) inadequate preparation. Logistic regression analysis showed that the risk factors for perceptual error were male sex (Odds ratio [OR], 2.45; 95% Confidence interval [CI], 1.16-5.18), isochromatic coloration (OR, 3.17; 95% CI, 1.47-6.84), greater curvature (OR, 2.31; 95% CI, 1.121-4.40), and lesion size ≤12 mm (OR, 1.74; 95% CI, 1.07-2.84). The sites of exposure errors were around incisura angularis, 11 (48%); posterior wall of the gastric body, 6 (26%); and antrum, 5 (21%).We identified MGCs in four categories and clarified their characteristics. Quality improvements in EGD observation, with attention to the risks of perceptual and site of exposure errors, can potentially prevent missing EGCs.Copyright © 2023 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.