図２〜図１３の病変↑は一見膿瘍に見えるが，周囲の炎症所見がないこと，小腸図６の３〜図８の５以外に腸管との癒着が少ないことと，図１０〜図１３の内容物が糞便様であるのに大腸（D：下行結腸，S：Ｓ状結腸，R：直腸）との接点がないなど，膿瘍としては異様である．憩室であれば図４の１〜図６の７は拡張しており，図６の３〜図８の５あたりから派生するのであろう．周囲の炎症所見を認めず憩室炎の診断は出来ない．手術で回盲部から約50cmの部位でMeckel憩室が確認された（図A：△，B：粘膜面，C：内容物の一部）．憩室内には1〜2cm大の小結石（腸石：図C）が充満していた．病理：Meckel’s diverticulitis of ileum．憩室壁は正常の腸管と同様の壁構造を呈する．粘膜は壊死に陥り，出血，ビラン，細菌感染を伴う．急性炎症細胞浸潤は軽度ながら固有筋層に至る．
“rule of ２”：昔憶えたことだが，頻度は2％，男女比が2:1，回盲部から2フィート以内に存在する，長さは2インチ，二つの主な合併症：腸閉塞と出血．

文献考察：Meckel憩室,1476例
Ann Surg. 2005 Mar;241(3):529-33.
Meckel diverticulum: the Mayo Clinic experience with 1476 patients (1950-2002).
Park JJ, Wolff BG, Tollefson MK, Walsh EE, Larson DR.

OBJECTIVE: Through a comprehensive review of the Mayo Clinic experience with patients who had Meckel diverticulum, we sought to determine which diverticula should be removed when discovered incidentally during abdominal surgery. SUMMARY BACKGROUND DATA: Meckel diverticula occur so infrequently that most articles have reported either small series or isolated cases. From these limited series, various conclusions have been reported without clearly indicating which incidental diverticula should be removed. METHODS: Medical records were reviewed of 1476 patients found to have a Meckel diverticulum during surgery from 1950 to 2002. Preoperative diagnosis; age; sex; date of surgery; and intraoperative, macroscopic, and microscopic findings from operative and pathology reports were recorded. Logistic regression analysis was used to determine which clinical or histologic features were associated with symptomatic Meckel diverticulum. The features analyzed were age; sex; length, base width, and ratio of length to base width of the diverticulum; and the presence of ectopic tissue or abnormal tissue (inflammation or enteroliths). RESULTS: Among the 1476 patients, 16% of the Meckel diverticula were symptomatic. The most common clinical presentation in adults was bleeding; in children, obstruction. Among patients with a symptomatic Meckel diverticulum, the male-female ratio was approximately 3:1. Clinical or histologic features most commonly associated with symptomatic Meckel diverticula were patient age younger than 50 years (odds ratio [OR], 3.5; 95% confidence interval [CI], 2.6-4.8; P 要旨：合併症は11歳以下では腸閉塞が多く，11歳以上では出血が多い．3-to-1 rule：有症状の75％は10歳以上，有症状の75％は男性，出血例の75％に異所性胃粘膜を認めた．手術中に偶然に発見されたMeckel憩室を切除すべきかどうかは異論の多い問題だが，肯定も否定もできなかった．有症状の大部分が，１）50歳以上，２）男性，３）憩室の長さが2cm以上，４）異所性胃粘膜を認めるもの（ただし外から肉眼的には判断不可能），である．1因子があれば有症状の頻度は17％，2因子で25％．3因子で42％，4因子を満たせば70％で，1因子でもあれば切除すべきである．