図１〜図６で上行結腸（A）が普通便を含んでいるので，小腸または右側結腸が出血源である可能性は否定的である．図１２の直腸1から逆行性に追跡すると，図６の7からＳ状結腸となり，図５の27あたりから下行結腸となる．図６〜図１０の△はextravasationで，Ｓ状結腸での出血である．図８〜図１０の▲の壁肥厚は，造影効果は強くないが，狭窄をきたしているので腫瘍性病変の可能性があり，憩室を認めず，S状結腸癌からの出血が考えられる．図Aと図Bは下腸間膜動脈の血管造影であるが，extravasationを認めず，出血源の病変も診断できない．血管造影では陽性所見を得るためには検査時に少なくとも0.5ml/min.の活動性出血が必要であるとされ，造影CTの方がextravasationの発見により敏感で，有用なことを示唆する．図Cが切除標本でＳ状結腸癌と診断された．

参考文献：下部消化管出血の診断に造影CTは有用．
Dig Surg. 2004 Aug 11;21(4):293-296.
Role of Contrast CT in Acute Lower Gastrointestinal Bleeding.
Rajan R, Dhar P, Praseedom RK, Sudhindran S, Moorthy S.

Objective: To evaluate the role of CT abdomen in the localization of acute lower gastrointestinal bleeding. Summary Background Data: The source of bleed in acute lower gastrointestinal bleeding is often difficult to localize. The role of CT in the evaluation of this group of patients has not been clearly addressed. Methods: A retrospective review of all patients with acute lower gastrointestinal bleeding over a 3-year period was carried out. When endoscopy failed to localize the source and bleeding continued, angiography and/or scintigraphy were carried out. In contrast, those who had normal endoscopies and had clinically stopped bleeding, underwent CT abdomen. Results: CT done in 7 patients with no evidence of active bleed identified a lesion in 6 (86%). Conclusions: CT may be useful in acute lower gastrointestinal bleeding where endoscopy fails to localize a lesion and bleeding has stopped temporarily. 　PMID: 15308870