虚血性大腸炎の臨床

Ischemic Colitis

　従来，消化管の虚血性病変は腸間膜動脈閉塞のように主幹動脈の閉塞による腸管壊死，壊死性病変，ないしは腸間膜血行不全のように広汎な腸管の出血性壊死を示す病変が注目されていた．しかし，1950年代から1960年代にかけて，直腸癌手術時の下腸間膜動脈の高位結紮や腹部大動脈瘤切除の合併症として，主に下腸間膜動脈領域の虚血性病変が注日されるようになり，Boleyら¹⁾による可逆性あるいは一過性の腸管虚血，Marstonら²⁾による虚血性大腸炎の報告以来，主幹血管の閉塞を伴わない大腸の虚血性疾患の病像が次第に明らかにされてきた．診断や検査の面からも小腸に比して大腸では内視鏡や生検による検索が容易なこともあって報告例も増加し，最近になって直腸の虚血性病変も記載されるようになってきた．

　During last 15 years, we have encountered 107 cases of intestinal lesions due to ischemia, including 18 cases of ischemic colitis.

　Ischemic colitis is now a well recognized and established clinical entity, which may occur spontaneously or following interference to the colonic circulation. There are two quite distinct forms of illness and it is rare for one to progress to the other. The severe form is due to fullthickness necrosis of the colonic wall, which presents as an abdominal catastrophe, and requires emergency operation with high mortality. The milder form presents as a left-sided acute abdomen, usually associated with diarrhea and rectal bleeding. The barium enema study is the most reliable diagnostic measure. Thumbprinting is the earliest change observed as early as three days after the onset of the symptoms. Colonoscopy also reveals the submusosal hemorrhage, mucosal slough and ulceration, in which case a biopsy may be sometimes diagnostic. These changes may occur at any site in the colon, but they are most common in the sigmoid. If these findings are borne in mind the diagnosis is in general not difficult. In these cases, the treatment should be conservative under the observation with barium enema study and colonoscopy. In a majority of the cases the complete healing will take place in a couple of weeks. A fibrous stricture will form in some cases treated in this way, but only a minority of these develops symptoms which are thought to be an indication for surgery.