図４〜図７で右側結腸内にニボーを形成する，やや高濃度の液状内容物（↑）は下血例では血液である可能性が高い．図８と図９で小腸にも液貯留（▲）を認め，回腸（臍を中心とした右上から左下への斜線を境に空腸は左側に，回腸は右側に位置する傾向がある）での出血を示唆する．単純CTはないが，Dが下行結腸だから，△は回腸内のextravasationである．入院後は下血なく，上部内視鏡検査と上腸間膜動脈造影で異常を認めなかった．最終ヘモグロビン値は10.2g/dlで，再度出血があれば手術を考慮することで退院した．

文献考察：下部消化管出血の７９％はCTで出血部位，病変を診断できる
Eur Radiol. 2003 Jan;13(1):114-7.
Helical CT in acute lower gastrointestinal bleeding.
Ernst O, Bulois P, Saint-Drenant S, Leroy C, Paris JC, Sergent G.

The purpose of this study was to assess the usefulness of helical CT in depicting the location of acute lower gastrointestinal bleeding. A three-phase helical CT of the abdomen was performed in 24 patients referred for acute lower gastrointestinal bleeding. The diagnosis of the bleeding site was established by CT when there was at least one of the following criteria: spontaneous hyperdensity of the peribowel fat; contrast enhancement of the bowel wall; vascular extravasation of the contrast medium; thickening of the bowel wall; polyp or tumor; or vascular dilation. Diverticula alone were not enough to locate the bleeding site. The results of CT were compared with the diagnosis obtained by colonoscopy, enteroscopy, or surgery. A definite diagnosis was made in 19 patients. The bleeding site was located in the small bowel in 5 patients and the colon in 14 patients. The CT correctly located 4 small bowel hemorrhages and 11 colonic hemorrhages（１５／19例：７９％）. Diagnosis of the primary lesion responsible for the bleeding was made in 10 patients. Our results suggest that helical CT could be a good diagnostic tool in acute lower gastrointestinal bleeding to help the physician to diagnose the bleeding site.　PMID: 12541118
追記：CTは単純,造影剤を入れ始めてから30秒後のearly phaseと2分後のdelayed phaseを撮る.造影剤は160mlを4ml/second で経静脈的に注入する.