Department of Obstetrics and Gynecology, Sant'Orsola Malpighi University Hospital, University of Bologna, Bologna, Italy.
Ultrasound Obstet Gynecol. 2013 Apr;41(4):430-5. doi: 10.1002/uog.12379.
To compare longitudinal changes in angle of progression (AoP) and midline angle (MLA) during the active second stage of labor according to the mode of delivery.
A three-dimensional transperineal ultrasound volume was acquired in a series of nulliparous women at the beginning of the active second stage (T1) and every 20 min thereafter (T2, T3, T4, T5 and T6). Following delivery, all ultrasound volumes were analyzed and AoP and MLA were measured.
Among 71 women included in the study, 58 underwent spontaneous vaginal delivery (group A) and 13 underwent operative delivery (group B) (eight by vacuum extraction and five by Cesarean section). When compared with Group B, Group A had a wider AoP only at T1 (140.0 ± 20.2° vs. 122.9 ± 16.7°; P = 0.010) and T2 (149.7 ± 20.7° vs. 126.9 ± 17.5°; P = 0.006). MLA was narrower in group A only at T3 (21.2 ± 11.7° vs. 40.8 ± 27.9°; P = 0.043), T4 (18.2 ± 15.0° vs. 47.4 ± 29.6°; P = 0.020) and T5 (18.3 ± 6.0° vs. 34.7 ± 4.2°; P = 0.034). On stepwise forward multiple logistic regression analysis, both AoP and MLA were independently associated with operative delivery (OR = 0.955 and OR = 1.018, respectively).
Ultrasonographic assessment of fetal head descent in the second stage of labor may play a role in the prediction of the mode of delivery.
根据分娩方式比较活跃第二产程中进展角（AoP）和中线角（MLA）的纵向变化。
对一系列初产妇在活跃第二产程开始时（T1）和此后每 20 分钟（T2、T3、T4、T5 和 T6）进行三维经会阴超声容积采集。分娩后，对所有超声容积进行分析，并测量 AoP 和 MLA。
在纳入研究的 71 名女性中，58 名接受了自发性阴道分娩（A 组），13 名接受了手术分娩（B 组）（8 名采用真空吸引，5 名采用剖宫产）。与 B 组相比，A 组仅在 T1（140.0±20.2° vs. 122.9±16.7°；P=0.010）和 T2（149.7±20.7° vs. 126.9±17.5°；P=0.006）时 AoP 更宽。A 组仅在 T3（21.2±11.7° vs. 40.8±27.9°；P=0.043）、T4（18.2±15.0° vs. 47.4±29.6°；P=0.020）和 T5（18.3±6.0° vs. 34.7±4.2°；P=0.034）时 MLA 更窄。逐步向前多变量逻辑回归分析显示，AoP 和 MLA 均与手术分娩独立相关（OR=0.955 和 OR=1.018）。
活跃第二产程中胎儿头部下降的超声评估可能对预测分娩方式起作用。
