岡庭 信司¹, 石井 重登¹, 岩下 和広²

Shinji OKANIWA¹, Shigeto ISHII¹, Kazuhiro IWASHITA²

¹飯田市立病院消化器内科, ²飯田市立病院超音波室

¹Department of Gastroenterology, Iida Municipal Hospital, ²Division of Ultrasound, Iida Municipal Hospital

キーワード : ultrasound, acute cholecystitis, acute cholangitis, diagnosis, severity assessment

胆道感染症は腹痛，黄疸，発熱といったCharcotの3徴を特徴とする比較的頻度の高い腹部感染症であり，早期に適切な対処を行わないと敗血症のような重症感染症を併発し死に至ることもある．一方，超音波検査は簡易で低侵襲な検査であるため救急患者の診断にも広く用いられており，急性胆管炎・胆嚢炎ガイドライン2013でも胆道感染症が疑われる全ての症例に対して初診時にまず超音波検査を行うべきとしている．急性胆嚢炎の診断には，胆嚢腫大，胆嚢壁肥厚，結石，デブリエコー，sonographic Murphy’s signが有用である．一方，急性胆管炎には特異的な画像所見はないが，Charcotの3徴と胆道系酵素や炎症反応の上昇に加え，超音波検査にて胆管拡張あるいは結石や腫瘍といった閉塞機転が指摘されれば急性胆管炎の診断が可能である．今回は，急性胆嚢炎と胆管炎の超音波所見と胆嚢炎の重症度判定に加え，急性胆嚢炎の患者が短時間に増悪する病態である胆嚢捻転，気腫性胆嚢炎，壊疽性胆嚢炎，胆嚢穿孔について解説する．

Acute cholangitis and cholecystitis are frequently encountered in daily practice presenting with abdominal pain, icterus, and fever. Those conditions may develop severe and potentially lethal infection such as sepsis without prompt medical care. As ultrasound (US) is a simple and less invasive modality, it is widely used for emergency patients. According to the Tokyo Guidelines (2013) for the management of acute cholangitis and cholecystitis, US should be performed at the initial consultation for all cases in which acute cholecystitis and/or cholangitis are suspected. Enlarged gallbladder, thickening of the gallbladder wall, gallbladder stones, debris echo, and ultrasonographic Murphy’s sign are the most characteristic US findings of acute cholecystitis. But, there are no direct imaging findings that show evidence of bile duct infection. However, biliary dilatation or its etiology detected by US in the presence of Charcot’s triad and general inflammatory response or cholestasis demonstrated by blood tests can support the diagnosis of acute cholangitis. We explain US findings of acute cholecystitis and cholangitis, and severity assessment for acute cholecystitis. We also highlight the mortal conditions of acute cholecystitis such as torsion of the gallbladder, emphysematous cholecystitis, gangrenous cholecystitis, and perforation of the gallbladder.