大腸癌見逃し例の検討とその対策―遡及的検討例の原因追究

Evaluation of Missed Colorectal Cancer and Measures against Oversight; Retrospective Analysis

要旨　1年以上の間隔をもって過去に注腸X線検査を受け，しかも10mm以上の病変の特定が可能であった進行大腸癌32例（男性22例，女性10例）34病変について，過去の写真で見逃された原因や問題点を解析し，以下の結果が得られた．①部位は右側結腸，特に上行結腸と盲腸の病変が多かった．②形状は，ほとんどが無茎性の隆起性病変で，特に扁平な病変（扁平型および扁平陥凹型）が22病変もあり，全体の64.7％を占めていた．③7病変（20.6％）は半月ひだの上に存在しており，この場合，半月ひだの限局的腫大として描出されていた．④1つの病変のみに注意が払われ，そのために見逃されていたもの（いわゆる“やぶにらみ”）は11病変（32.4％）であった．⑤前処置との関係では，小糞塊や糞汁のため，診断が不十分であったと思われるものは6病変（17.6％）であった．⑥回盲弁の上，または上行結腸でも回盲弁の近傍に病変があったため，腫大した回盲弁とみなされていた病変は6病変（17.6％）であった．⑦X線検査で病変を指摘（含む疑い）していたが，その後の医療側の指示や経過観察に，問題かあったと思われる病変は5病変（14.8％）であった．この検討の結果を踏まえて，病変を見逃さないための診断上の留意点と，今後の対応について述べた．

　We evaluated 33 lesions from 32 patients with advanced colorectal cancer (22 male and 10 female patients), who underwent barium enema revealing lesions more than 10 mm in size, more than one year prior to the final examinations. The cause and problems associated with overlooking by the previous examinations were summarized as follows: 1) The lesions were common in the right colon, especially in the ascending colon and cecum. 2) As for the shape of lesions most of the missed lesions were sessile elevated lesions, particularly flat lesions (flat, and flat with depression type) which accounted for 64.7% of the missed lesions. 3) Seven lesions (20.6%) were located on the semilunar folds and were misdiagnosed as localized swelling of semilunar folds. 4) Eleven lesions (32.4%) were overlooked when another lesions were detected. 5) Six lesions (17.6%) were missed because of the intraluminal contents due to unsatisfactory preparations. 6) Six lesions (17.6%) were located on or near the Bauhin's valve in the ascending colon and were misdiagnosed as swelling of Bauhin's valve. 7) Five lesions were already pointed out by the previous x-ray examinations, but failure of follow-up study or improper direction to the patients caused delay of the final diagnosis. In conclusion, we proposed the way to prevent overlooking and countermeasures for the future.