松本 泰弘, 梁 栄治, 鎌田 英男, 綾部 琢哉

Yasuhiro MATSUMOTO, Eiji RYO, Hideo KAMATA, Takuya AYABE

帝京大学医学部付属病院産婦人科

Department of Obstetrics and Gynecology, Teikyo University School of Medicine

キーワード : elastography, tissue elasticity, uterine contraction, threatened preterm delivery, labor

目的：エラストグラフィを用いて，切迫早産および分娩時の子宮筋収縮を，客観的に判断できるか検討した．対象と方法：切迫早産2例と，分娩経過中の妊婦15例の計17例を対象とした．腹壁の脂肪層と子宮筋層を，エラストグラフィの画像として記録し，子宮筋収縮によって筋層の色彩に変化があるか観察した．また，脂肪層と子宮筋層の歪みやすさを，それぞれB，Aとして数値化，B/A比を算出し，子宮筋収縮時と弛緩時のB/A比に差があるかを比較した．さらに，収縮時のB/A比が弛緩時のB/A比の何倍になっているかを算出した．結果と考察：全ての観察例において，子宮筋収縮に伴って，筋層の色彩が変化した．また，切迫早産例におけるB/A比は，子宮筋収縮時に28.2，弛緩時では1.3となり，有意な差を認めた．同様に，分娩第1期潜伏期では，それぞれ31.2と2.5，分娩第1期活動期では49.9と2.64，分娩第2期では47.9と6.13となり，全ての時期においてB/A比に差を認めた．切迫早産における収縮時のB/A比は弛緩時の21.7倍と最高値で，分娩第2期での同じ値は7.8倍と最低値であった．エラストグラフィを用いることで，子宮筋の収縮を客観的かつ定性的に判定できたが，収縮力など定量的評価をするためには，多くの課題があった．結論：エラストグラフィを用いることで子宮筋の収縮を客観的，定性的に評価することが可能である．

Purpose: We investigated whether ultrasound elastography was useful for evaluating uterine muscle contractions in women with threatened premature and terminal labor. Subjects and Methods: A total of 17 pregnant women (two women with threatened premature labor and 15 women with terminal labor) were recruited to the study. Elastographic images of abdominal fat and the uterine muscular layer were recorded during uterine contractions and relaxations, and color changes in the muscle were observed. We measured the elasticity of uterine muscle (A) and fatty tissue (B), and calculated B/A ratios. The ratio during contractions was compared with that during relaxations by Wilcoxon's test. Results and Discussion: The muscle color changed with its contraction in all women. The B/A ratios during contractions and relaxation were as follows, respectively: 28.2 and 1.3 for threatened premature labor, 31.2 and 2.5 for the latent phase of the first stage of labor, 49.9 and 2.64 for the active phase of the first stage of labor, and 47.9 and 6.13 for the second stage of labor. There were differences between the two in all stages. Conclusions: Ultrasound elastography made it possible to evaluate whether uterine muscle contracts or not in women with premature preterm and term labor.