大腸小・微小病変に対する治療と偶発症─cold snare polypectomyの課題と可能性

Cold Snare Polypectomy for Subcentimeter Colorectal Polyps:Therapies and Adverse Events

要旨●通電を伴わないCSPは，10mm未満の小さなポリープに対する偶発症の少ない治療法として知られているが，ポリープ遺残の可能性，後出血の実際の頻度について前向きに検討した報告は少ない．今回，筆者らはCSPのポリープ遺残の可能性および後出血率を前向きに検討した．CSPの67.1%では組織学的にポリープの切除断端の判定が不明瞭（HMX）であったが，CSPで摘除後，粘膜欠損をEMRにて追加切除したところ3.9%のみに遺残を認めた．切除標本での切除断端の評価は，実際の遺残を全く反映していないと言える．また，遅発出血はポリープ単位で0.3%，症例単位で1.1%であり，後出血は皆無ではないものの非常に少ない結果であった．病変遺残の可能性，遅発出血の可能性を十分に認識し，適応を十分理解すれば，CSPは安全に実施しうる．

　CSP（cold snare polypectomy）is a promising technique that does not use electrocautery. CSP is generally accepted as a less invasive procedure that presents a lower risk of adverse events. We investigated the incomplete resection rate and bleeding rate after CSP in single-center prospective studies. The incomplete resection rate was 3.9%［95%CI（confidence interval）1.7%-6.1%］; however, the polyp lateral margins could not be assessed adequately for 67% of the retrieved polyps. Therefore, we suggest that the assessment of lateral margins in the resected specimens is not appropriate for the evaluation of residual in situ polyps. Additionally, delayed bleeding that required endoscopic intervention occurred in four patients（1.1% ; 95%CI, 0.03%-2.2%）with four polyps（0.3% ; 95%CI, 0.007%-0.6%）, all of which were oozing and easily managed with endoscopic clipping. Although it was not eliminated completely, the incidence of delayed bleeding after CSP was remarkably low. Based on our results, we conclude that CSP can be used as a standard endoscopic therapy for subcentimeter polyps.