図１〜図３で胃液よりやや高濃度の腹水（※）がある．図６と図７で脾損傷（↑）を認め，図６〜図１４の△はextravasationを示している．図６の虚脱したIVCは重度のhypovolemiaを意味し出血を裏付ける．

図Aと図Bの血管造影で仮性動脈瘤（▲）とextravasation（△）を認め，コイル（図C：白矢印）で塞栓し止血に成功した．Hb：14.1→9.7g/dl．CTでextravasation，extravasationを伴う仮性動脈瘤，extravasationを伴わない仮性動脈瘤を鑑別するにはdouble phase 造影CTが必須である．

参考症例（脾臓損傷 IIIa）：17歳女性．原付バイクで転倒し腹部を打撲した．右大腿骨骨折もある．血圧：118/75mmHg，脈拍：110/分．腹部全体に圧痛を認める．Double phase 造影CT．図１３〜図１６は翌日の造影CT．

上段の来院時のCTで相当量の腹水があり，図４と図８で脾損傷（↑）を認める．早期相（Early）図１と図２の△は，晩期相（Delayed）図５と図６で大きさと形態にほとんど変化を示さない（▲）ので仮性動脈瘤と解釈する．Extravasationを認めない．下段の血管造影でextravasationを伴わない仮性動脈瘤（白矢印）が確認され，スポンゼル細片で塞栓し，消失したことを確認した（図１１と図１２）．しかし翌日には腹部膨満が出現し，Hbが低下した．図１３〜図１６で腹水の増量とextravasation（△）を認めた．肝臓が縮小しているのは腹圧上昇によるものか？ 脾臓が造影されていないので脾門部での出血を疑う．手術で脾門部に裂創を認め活動性に出血していたので脾臓を摘出した．このようにCT撮影時や血管造影時には一時的に止血していて，後で再出血を起こす症例もあることを忘れてはならない．

文献考察：USによるIVC前後径計測とhypovolemia．IVC前後径はtransient responder groupで有意に低下していた（transient responder：responder group (6.5 +/- 0.5 mm; mean +/- SE vs. 10.7 +/- 0.7 mm, p J Trauma. 2007 Dec;63(6):1245-8; discussion 1248.
Hypovolemic shock evaluated by sonographic measurement of the inferior vena cava during resuscitation in trauma patients.
Yanagawa Y, Sakamoto T, Okada Y.

BACKGROUND: Inferior vena cava (IVC) diameter immediately after fluid resuscitation has not yet been investigated in trauma patients with shock on arrival. METHODS: Between June 2004 and May 2005, 30 trauma patients with hemorrhagic shock were prospectively investigated. Using ultrasound, we measured maximum anterior-posterior diameter of the IVC just below the diaphragm in the hepatic segment, in the expiratory phase. This was performed on arrival and when systolic blood pressure had been raised to over 90 mm Hg by fluid resuscitation in the emergency room. Subjects were divided into two groups: a transient responder group (n = 17) in which shock recurred after leaving the emergency room and a responder group (n = 13) in which blood pressure remained stable. RESULTS: There were no significant differences between the two groups regarding age or gender, or regarding vital signs or IVC diameter on arrival. Average injury severity score in the transient responder group was significantly greater than that in the responder group. After fluid resuscitation, no significant intergroup differences were observed regarding vital signs. However, IVC diameter was significantly smaller in the transient responder group than in the responder group (6.5 +/- 0.5 mm; mean +/- SE vs. 10.7 +/- 0.7 mm, p