肝臓の右葉と左葉を分断する大きな，低吸収値を呈する肝損傷がある．日本外傷学会肝損傷分類の，広範囲の組織挫滅を伴う複雑型深在性肝損傷IIIｂである．肝右葉周囲の※は，位置的には被膜下であるが，脾臓上極周囲（図３と図４：※）と下腹部と骨盤腔内（図１８と図１９： ※）にも相当量の腹水があり単純な被膜下血腫（I 型）ではない．図２と図３の▲は辺縁が鮮明で，delayed phaseの図６と図７で大きさと形に変化がなく仮性動脈瘤であり，extravasation（造影剤の血管外漏出）ではない．図２と図３の△は辺縁が不鮮明でdelayed phaseの図６〜図８で大きくなって拡散しているのでextravasationである．図９と図１０の↑は図１１の正常血管↑に連続するし，delayed phaseで大きさと形に変化がないのでextravasationではなく正常血管である．このようにextravasationの診断と，extravasationと仮性動脈瘤との鑑別にdouble phase造影CTは極めて重要である．脾臓の読影でピッツフォールがある．図１６と図１７の脾臓の白矢印は周囲に血腫や腹水を認めず，不整（ぎざぎざ）のない平滑な直線だから裂創ではなく，生理的な分葉線である．脾臓損傷と誤診しないよう気をつけたい．出血量は （計算方法はExpertコース症例TE１の回答欄から下段に再掲 ），図４のような肝内血腫（白矢印）は短軸と長軸とスライス数を掛けて大まかな体積計算をし，7x10x6スライスとして420，半分は造影効果を失った肝組織と解釈し210ml，図4の脾臓周囲は200ml，図１２の肝周囲は500ml，図１８で200＋350＝550ml，図１９の骨盤腔は250mlで，合計1710mlとなる．大量出血とextravasationおよび仮性動脈瘤を認めたので血管造影可能な病院へ輸血しながら転送され，塞栓術（TAE：transcatheter arterial embolization）にて止血に成功した．

出血量の計算方法．腹腔内を，１：肝周囲（右横隔膜下），２：脾臓周囲（左横隔膜下），３：Morison窩，４：右傍結腸溝，５：左結腸溝，６：小腸間，７：骨盤腔の７つの部位に分ける．腹水の厚さを各部位の平均的な場所でおおまかに計測し，1cm未満を50ml，1cm＝100ml，1．5cm＝150ml，2cm＝200ml，2．5cm＝250ml，3cm＝300ml．．．5cm＝500mlとし合計する．骨盤腔は比較的横径が狭いので半分値で計算する（例：前後に4cmあれば200ml）．

参考症例（肝損傷 Ib）：21歳女性．交通事故で腹部を打撲して来院．血圧：128/70mmHg，脈拍：78/分．右上腹部に圧痛がある．Double phase造影CT（早期相：Early，晩期相：Delayed）である．

肝右葉に中心性破裂（Ib）を認めるが，肝周囲に腹水や血腫はない．図４と図９の△は，晩期相で大きくなり広がっている（▲）のでextravasationである．図６と図７の↑は肝実質． Double phase造影CTだからextravasationの診断は容易である．被膜損傷のない（腹腔内出血を伴わない）中心性破裂だからTAEを行わず順調に経過した．Hb：14.2→12.1g/dl．

文献考察：TAEは極めて有効な治療法だが，AAST Grade IVとVで，血圧を維持するのに2000ml以上の輸液を必要な症例は手術の適応
１）J Trauma. 2002 Jun;52(6):1091-6.
The efficacy and limitations of transarterial embolization for severe hepatic injury.
Hagiwara A, Murata A, Matsuda T, Matsuda H, Shimazaki S.

Department of Traumatology and Critical Care Medicine, Kyorin University, School of Medicine, Tokyo, Japan.

BACKGROUND: The efficacy of transarterial embolization (TAE) for severe blunt hepatic injury has been reported. We performed a prospective study evaluating the efficacy and the limitation of TAE from January 1996 to December 2000. METHODS: All patients with blunt abdominal injury who could be stabilized by fluid resuscitation underwent computed tomographic (CT) scan examinations. Patients with CT scan evidence of hepatic injury were classified into five grades according to CT scan findings on the basis of the injury scale of the American Association for the Surgery of Trauma (Mirvis classification). All patients with CT scan grade 3 to 5 injury underwent angiography. When angiography showed extravasation of contrast medium extending from hepatic arterial branches, TAE was performed. RESULTS: Of 612 patients with blunt abdominal trauma, 51 had CT scan grade 3 to 5 injury. Thirty-seven of these patients had a CT scan grade 3 injury and 18 underwent TAE. One of 19 patients who did not undergo TAE developed a delayed hemorrhage on day 6 and required a laparotomy. All 13 patients with a CT scan grade 4 injury had angiographic findings of the extravasation. TAE was successful in 11 patients and unsuccessful in 2. Five patients with a CT scan grade 4 injury required laparotomy. One developed a delayed hemorrhage on day 4. The remaining four patients had a major venous injury (a right lobectomy was performed in two with inferior vena cava injury, and a gauze packing in two with hepatic venous injury). One patient with a CT scan grade 5 injury underwent immediate laparotomy after TAE. Laparotomy revealed inferior vena cava injury and a right lobectomy was performed. Only two patients who underwent a lobectomy died of an uncontrollable hemorrhage. All CT scans of patients with hepatic venous or inferior vena cava injury showed a large low-density area (> or = 10 cm) with involvement of these vessels. The volumes of fluid resuscitation needed from admission until TAE ranged from 2,109 to 2,638 mL/h. CONCLUSION: It was considered that the combination of the presence of a CT scan grade 4 or 5 lesion and the fluid requirements of more than 2,000 mL/h to maintain normotension indicated the absolute necessity of surgery. We felt that these patients were not candidates for TAE, and should undergo immediate laparotomy.　PMID: 12045635

２）J Trauma. 2004 Aug;57(2):271-6; discussion 276-7.
The usefulness of transcatheter arterial embolization for patients with blunt polytrauma showing transient response to fluid resuscitation.
Hagiwara A, Murata A, Matsuda T, Matsuda H, Shimazaki S.

Department of Traumatology and Critical Care Medicine, School of Medicine, Kyorin University, Tokyo, Japan. hagiwarapupu@jcom.home.ne.jp

BACKGROUND: This study aimed to determine whether nonsurgical management using transcatheter arterial embolization (TAE) is safe for patients with blunt multiple trauma who transiently respond to the initial fluid resuscitation. METHODS: Contrast computed tomography was performed for patients with blunt abdominal injuries, excluding those who did not respond to initial fluid resuscitation. Angiography was performed for patients with injuries showing contrast extravasation or solid organ injury classified, according to the American Association for the Surgery of Trauma, as grade 3 or higher on computed tomography. Transcatheter arterial embolization was performed when angiography showed arterial extravasation. The protocol was abandoned for any patients who became profoundly hypotensive (with systolic blood pressure 60 mm Hg or lower) during computed tomography or angiography. RESULTS: Between January 2000 and December 2002, 269 patients with blunt abdominal injuries underwent TAE immediately after admission. Of these patients, 41 had injuries in at least two regions and underwent TAE for these regions. Among them, 22 patients were hemodynamically stable or showed rapid response to fluid resuscitation. The nonsurgical treatment was successful in all these cases. The remaining 19 patients (Injury Severity Score, 37.3 +/- 8.2), who showed a transient response, were the subjects of this study. Of these patients, 15 underwent TAE for injuries in two regions (13 pelvic fractures, 7 splenic injuries, 6 hepatic injuries, 3 facial bleeding, and 1 renal injury), and 4 patients underwent TAE for injuries in three regions (4 had splenic injuries, 3 hepatic injuries, 2 renal injuries, 2 pelvic fractures, and 1 facial bleeding). For all these patients, TAE was successfully performed. Before TAE, the systolic blood pressure was 79.9 +/- 8.4 mm Hg, and the shock index was 1.45 +/- 0.25 mm Hg. After TAE, the corresponding values were 120.6 +/- 19.3 mm Hg and 0.87 +/- 0.16 mm Hg, respectively (p 追記：低血圧を呈する症例は，一般的には血管造影よりも手術の適応であるが，初期輸液2000mlで血圧の改善が認められるならTAEを施行して保存的治療が可能である