Yano Eriko, Iriyama Takayuki, Sayama Seisuke, Ariyosi Yu, Akiba Naoya, Ichinose Mari, Toshimitsu Masatake, Seyama Takahiro, Sone Kenbun, Kumasawa Keiichi, Nagamatsu Takeshi, Nakayama Toshio, Kobayashi Koichi, Osuga Yutaka
Department of Obstetrics and Gynecology, Faculty of Medicine, The University of Tokyo, Tokyo, Japan (Drs Yano, Iriyama, Sayama, Ariyosi, Akiba, Ichinose, Toshimitsu, Seyama, Sone, Kumasawa, Nagamatsu, and Osuga).
Department of Obstetrics and Gynecology, Faculty of Medicine, The University of Tokyo, Tokyo, Japan (Drs Yano, Iriyama, Sayama, Ariyosi, Akiba, Ichinose, Toshimitsu, Seyama, Sone, Kumasawa, Nagamatsu, and Osuga).
Am J Obstet Gynecol MFM. 2023 Jan;5(1):100755. doi: 10.1016/j.ajogmf.2022.100755. Epub 2022 Sep 23.
No previous study has evaluated the transitions of intrapartum transperineal ultrasound parameters during labor progression in cephalic malposition.
We aimed to quantitate the characteristic trends of fetal head position and descent in cephalic malposition by analyzing the transitions of intrapartum transperineal ultrasound parameters and explore an indicator associated with the degree of cephalic malposition.
We retrospectively analyzed pregnant women who delivered at term from January 2018 to December 2020 at the University of Tokyo Hospital. The fetal occipital position was classified as occiput anterior and nonocciput anterior according to the fetal occipital angle of 0° to 75° and 75° to 180°, respectively. Fetal occipital angle was defined by the midline angle and position of the ocular orbit. The differences in the trends of head direction, head-symphysis distance, and progression distance relative to the angle of progression between occiput anterior and nonocciput anterior cases were evaluated. In addition, the parameters that showed differences were analyzed to evaluate their relationship to the degree of cephalic malposition.
A total of 502 images (occiput anterior, 319; nonocciput anterior, 183) met the inclusion criteria. The distribution of head direction values relative to the angle of progression was smaller in the nonocciput anterior group than in the occiput anterior group, whereas the head-symphysis distance and progression distance values relative to the angle of progression showed no difference in their distribution between the occiput anterior and nonocciput anterior groups. The ratio of head direction to the angle of progression was significantly smaller in the nonocciput anterior group than in the occiput anterior group (median [interquartile range], 0.03 [-0.02 to 0.10] vs 0.21 [0.12-0.28]; P<.0001). Furthermore, this ratio was negatively correlated with fetal occipital angle (Spearman correlation coefficient, -0.66).
Our results indicated that the head direction to angle of progression ratio reflects the deviation in the fetal head direction toward the maternal dorsal side, and decreases in proportion to the degree of cephalic malposition. This concept of deviation in the head direction as an indicator for evaluating cephalic malposition with intrapartum transperineal ultrasound may contribute to improving labor management in the case of cephalic malposition.
既往尚无研究评估头先露胎位异常分娩过程中经会阴超声参数的变化。
通过分析分娩期经会阴超声参数的变化，定量头先露胎位异常时胎头位置和下降的特征趋势，并探索与头先露胎位异常程度相关的指标。
我们回顾性分析了2018年1月至2020年12月在东京大学医院足月分娩的孕妇。根据胎儿枕骨角分别为0°至75°和75°至180°，将胎儿枕骨位置分为枕前位和非枕前位。胎儿枕骨角由眼眶的中线角度和位置定义。评估枕前位和非枕前位病例在头方向、头-耻骨联合距离以及相对于进展角度的进展距离趋势上的差异。此外，对显示出差异的参数进行分析，以评估它们与头先露胎位异常程度的关系。
共有502幅图像（枕前位319幅；非枕前位183幅）符合纳入标准。相对于进展角度，非枕前位组头方向值的分布小于枕前位组，而相对于进展角度，头-耻骨联合距离和进展距离值在枕前位组和非枕前位组之间的分布没有差异。非枕前位组头方向与进展角度的比值显著小于枕前位组（中位数[四分位间距]，0.03[-0.02至0.10]对0.21[0.12 - 0.28]；P<0.0001）。此外，该比值与胎儿枕骨角呈负相关（Spearman相关系数，-0.66）。
我们的结果表明，头方向与进展角度的比值反映了胎头方向向母体背侧的偏移，且与头先露胎位异常程度成比例降低。将头方向偏移这一概念作为分娩期经会阴超声评估头先露胎位异常的指标，可能有助于改善头先露胎位异常情况下的分娩管理。
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