Department of Obstetrics and Gynecology, Landspitali - The National University Hospital of Iceland, Reykjavík, Iceland; Faculty of Medicine, University of Iceland, Reykjavík, Iceland.
deCODE genetics, Reykjavík, Iceland.
Am J Obstet Gynecol. 2021 May;224(5):514.e1-514.e9. doi: 10.1016/j.ajog.2020.10.054. Epub 2020 Nov 15.
Improved information about the evolution of fetal head rotation during labor is required. Ultrasound methods have the potential to provide reliable new knowledge about fetal head position.
The aim of the study was to describe fetal head rotation in women in spontaneous labor at term using ultrasound longitudinally throughout the active phase.
This was a single center, prospective cohort study at Landspitali - The National University Hospital of Iceland, Reykjavík, Iceland, from January 2016 to April 2018. Nulliparous women with a single fetus in cephalic presentation and spontaneous labor onset at ≥37 weeks' gestation were eligible. Inclusion occurred when the active phase could be clinically established by labor ward staff. Cervical dilatation was clinically examined. Fetal head position and subsequent rotation were determined using both transabdominal and transperineal ultrasound. Occiput positions were marked on a clockface graph with 24 half-hour divisions and categorized into occiput anterior (≥10- and ≤2-o'clock positions), left occiput transverse (>2- and <4-o'clock positions), occiput posterior (≥4- and ≤8 o'clock positions), and right occiput transverse positions (>8- and <10-o'clock positions). Head descent was measured with ultrasound as head-perineum distance and angle of progression. Clinical vaginal and ultrasound examinations were performed by separate examiners not revealing the results to each other.
We followed the fetal head rotation relative to the initial position in the pelvis in 99 women, of whom 75 delivered spontaneously, 16 with instrumental assistance, and 8 needed cesarean delivery. At inclusion, the cervix was dilated 4 cm in 26 women, 5 cm in 30 women, and ≥6 cm in 43 women. Furthermore, 4 women were examined once, 93 women twice, 60 women 3 times, 47 women 4 times, 20 women 5 times, 15 women 6 times, and 3 women 8 times. Occiput posterior was the most frequent position at the first examination (52 of 99), but of those classified as posterior, most were at 4- or 8-o'clock position. Occiput posterior positions persisted in >50% of cases throughout the first stage of labor but were anterior in 53 of 80 women (66%) examined by and after full dilatation. The occiput position was anterior in 75% of cases at a head-perineum distance of ≤30 mm and in 73% of cases at an angle of progression of ≥125° (corresponding to a clinical station of +1). All initial occiput anterior (19), 77% of occiput posterior (40 of 52), and 93% of occiput transverse positions (26 of 28) were thereafter delivered in an occiput anterior position. In 6 cases, the fetal head had rotated over the 6-o'clock position from an occiput posterior or transverse position, resulting in a rotation of >180°. In addition, 6 of the 8 women ending with cesarean delivery had the fetus in occiput posterior position throughout the active phase of labor.
We investigated the rotation of the fetal head in the active phase of labor in nulliparous women in spontaneous labor at term, using ultrasound to provide accurate and objective results. The occiput posterior position was the most common fetal position throughout the active phase of the first stage of labor. Occiput anterior only became the most frequent position at full dilatation and after the head had descended below the midpelvic plane.
需要提高关于分娩过程中胎儿头部旋转演变的信息。超声方法有可能为胎儿头部位置提供可靠的新知识。
本研究旨在使用超声在活跃期内纵向描述足月自然分娩的妇女的胎儿头部旋转。
这是冰岛雷克雅未克 Landspitali - 国立大学医院的一项单中心前瞻性队列研究，时间为 2016 年 1 月至 2018 年 4 月。纳入标准为单胎头位、有自发临产且妊娠 37 周以上的初产妇。当产程活跃期可由产房工作人员临床确定时纳入。宫颈扩张进行临床检查。使用经腹和经会阴超声确定胎儿头部位置和随后的旋转。枕骨位置在时钟图上用 24 个半小时的划分标记，并分为枕骨前位（≥10 点和≤2 点位置）、左枕骨横位（>2 点和<4 点位置）、枕骨后位（≥4 点和≤8 点位置）和右枕骨横位位置（>8 点和<10 点位置）。用超声测量胎头下降的头盆距和进展角。临床阴道检查和超声检查由单独的检查者进行，彼此不透露结果。
我们在 99 名妇女中观察了相对于骨盆初始位置的胎儿头部旋转，其中 75 名妇女自然分娩，16 名妇女使用器械辅助分娩，8 名妇女需要剖宫产。纳入时，26 名妇女的宫颈扩张 4 cm，30 名妇女的宫颈扩张 5 cm，43 名妇女的宫颈扩张≥6 cm。此外，4 名妇女检查 1 次，93 名妇女检查 2 次，60 名妇女检查 3 次，47 名妇女检查 4 次，20 名妇女检查 5 次，15 名妇女检查 6 次，3 名妇女检查 8 次。首次检查时最常见的枕骨后位（99 例中有 52 例），但其中 4 或 8 点位置的枕骨后位居多。在整个第一产程中，枕骨后位在>50%的病例中持续存在，但在完全扩张后的 80 例妇女中有 53 例（66%）为前位。在头盆距≤30mm 和进展角≥125°（对应临床站+1）的情况下，枕骨位置在前 75%的病例中，在 73%的病例中。所有初始的枕骨前位（19 例）、77%的枕骨后位（52 例中的 40 例）和 93%的枕骨横位（28 例中的 26 例）随后均在枕骨前位分娩。在 6 例中，胎儿头部从枕骨后位或横位旋转过 6 点位置，导致旋转>180°。此外，8 例剖宫产分娩的妇女中有 6 例在活跃期内胎儿始终处于枕骨后位。
我们使用超声对自然分娩的初产妇在活跃期的胎儿头部旋转进行了研究，提供了准确和客观的结果。在第一产程活跃期，枕骨后位是最常见的胎儿位置。只有在完全扩张且胎头下降至中骨盆平面以下时，枕骨前位才成为最常见的位置。
