急性腹症の超音波診断―小腸疾患を中心に

Acute Abdomen―Ultrasonographic Findings of the Small Intestinal Lesions

要旨　一般に消化管の超音波検査は，腸管内のガスが障害となるので不適当と考えられてきたが，実際はそうでなく，腸疾患が発生すると炎症や閉塞による浮腫や腸管内液体貯溜が起こり，ガスも排除されるため病巣は超音波検査にとって好条件となる．急性腹症は，この点から最も適当な状況で，病巣の存在診断は容易にでき，条件が良ければその組織診断まで推測することができる．以上の理由から，最近は超音波検査は腸疾患の第一選択の検査の1つに位置するようになった．腸疾患は，腸管壁の肥厚と腸管の拡張の要素で構成され，壁の肥厚があれば必ずその部位に病巣があると考えられる．また，腸管壊死の診断は腸管の壁構造の破壊かあるいは腸管壁に付着するhigh echo点の壊死物質の存在によってなされる．

　It has been stated that ultrasonography is not useful in detecting gastrointestinal (GI) tract lesions, because air in the GI tract interferes the ultrasonographic images. Edematous or obstructive changes in the GI tract can make ultrasonography a more useful tool for diagnosis.

　Inflammatory edema or obstructed fluid eliminates air components from the GI tract so that ultrasonography can work better to detect abnormalities and identify even histological layers of the intestinal wall. Therefore it can be said that acute abdomen may be a "favorable" condition for ultrasonographic examination.

　We often detect low echogenic lesions in acute abdomen cares. For instance, thickening of the bowel wall and dilated loops reflect such ultrasonographic findings. Ischemic bowel necrosis can be detected as disappearance of histological layers of the bowel wall. The high echogenic spots on the surface of the lumen are specific to bowel necrosis.

　It can be said that ultrasonographic examination is one of the primary diagnostic methods for acute gastrointestinal diseases. A localized abnormal echogenic area may indicate that there occurs something abnormal.