直腸肛門機能検査―defecographyを含めて

Physiologic Tests of the Anorectum

要旨　直腸肛門機能検査は直腸肛門の貯留能・括約能・排泄能を定量的・客観的に評価するための検査法で，transit study，肛門内圧測定，肛門括約筋筋電図，陰部神経終末伝導速度測定，直腸肛門感覚検査，直腸肛門反射の記録，排便造影(defecography)などがある．内視鏡検査などとは異なり，機能検査は疾患を直接的に診断する方法ではないため，その結果を診療に活用する際には，患者の自覚症状や器質的異常との整合性を十分吟味しなければならない．

　Temporary stool retention in the rectum, prevention of stool leakage by the sphincter mechanism, and timely and sufficient evacuation are important functions of the anorectum. Anorectal physiologic tests aim to evaluate these functions objectively and quantitatively. Anal manometry, anal endosonography, rectal sensory tests, recording of rectoanal inhibitory reflex and defecography are performed commonly in clinical settings. Sphincter electromyography and the measurement of pudendal nerve terminal motor latency are tools for the differential diagnosis of the weakness of the external anal sphincter. Transit study is important in the evaluation of chronic constipation. Although anorectal physiologic tests are clinically useful in a number of anorectal diseases and conditions, the results should be carefully interpreted, with patients' subjective symptoms and organic abnormalities being considered.