Predictive value of intrapartum ultrasound indicators for difficulty assessment in vacuum-assisted delivery
10.3760/cma.j.cn113903-20240428-00317
- VernacularTitle:产时超声指标预测胎头吸引产术的难易程度
- Author:
Pei ZHANG
1
;
Yuan ZHANG
1
;
Qingqing WANG
1
;
Hongying HOU
1
;
Zhenyan HAN
1
Author Information
1. 中山大学附属第三医院妇产科，广州 510630
- Publication Type:Journal Article
- Keywords:
Intrapartum ultrasound;
Angle of progression;
Head-perineum distance;
Vacuum-assisted delivery
- From:
Chinese Journal of Perinatal Medicine
2025;28(3):194-202
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the predictive role of intrapartum ultrasound indicators on the difficulty of vacuum-assisted delivery.Methods:A prospective cohort study was conducted. The study subjects were singleton pregnant women hospitalized for delivery at the Third Affiliated Hospital of Sun Yat-sen University from February 2021 to December 2022, who had indications for vacuum-assisted delivery, and completed intrapartum ultrasound examination within 10 minutes before the procedure. Intrapartum ultrasound indicators included fetal position, angle of progression (AOP), and head-perineum distance (HPD). Based on the difficulty of vacuum-assisted delivery, the subjects were divided into easy and difficult groups. The fetal position, AOP, and HPD before vacuum-assisted delivery and delivery outcomes were compared between the two groups to explore the correlation and predictive value of intrapartum ultrasound indicators on the difficulty of vacuum-assisted delivery. Statistical and predictive value analyses were performed using independent-sample t-test, U-test, Chi-square (or Fisher's exact) test, logistic regression analysis, and receiver operating characteristic (ROC) curve. Results:A total of 162 cases were included in the study, with 120 in the easy and 42 in the difficult groups. The age of the 162 pregnant women ranged from 20 to 44 years, with an average of (30.6±3.9) years; 107 cases (66.0%) were first pregnancies, and 139 cases (85.8%) were primipara. (1) The fetal head stations in the difficult and easy groups were 2.3 (2.0-2.5) cm and 2.0 (2.0-2.5) cm, respectively, with no statistically significant difference ( P>0.05). The AOP during the interval and contraction periods and the ΔAOP in the difficult group were smaller than those in the easy group [ (138.1±8.8) vs. (143.8±7.9), t=3.89; (148.7±9.3) vs. (157.9±8.9), t=5.67; and (10.6±6.4) vs. (14.1±6.3), t=3.08; all P<0.01], while the HPD during the interval and contraction periods and ΔHPD in the difficult group were greater than those in the easy group [(3.4±0.5) cm vs. (3.2±0.4) cm, t=－2.69; (2.8±0.5) cm vs. (2.4±0.5) cm, t=－4.70; (－0.5±0.4) cm vs. (－0.8±0.5) cm, t=－2.83; all P<0.01]. (2) In the difficult group, seven cases required forceps delivery after 2-3 vacuum cup detachments; in the easy group, all cases were successfully delivered after 1-2 vacuum tractions. The duration of vacuum extraction was longer in the difficult group [7.0 (6.0-10.0) min vs. 3.0 (2.0-3.0) min, Z=9.65] (all P<0.001). (3) In the difficult group, four cases had severe maternal and neonatal delivery complications, including two cases of shoulder dystocia, one case of vesicovaginal fistula after failed vacuum extraction converted to forceps delivery, and one case of third-degree perineal tear after failed vacuum extraction converted to forceps delivery. In the easy group, one case had shoulder dystocia with mild neonatal asphyxia. The rate of vaginal tears in the difficult group was higher than in the easy group [47.6% (20/42) vs. 29.2% (35/120)] ( χ2=4.72, P=0.030). The incidence of postpartum hemorrhage in the difficult and easy groups was 11.9% (5/42) and 8.3% (10/120), respectively, with no statistically significant difference (Fisher's exact test, P=0.539). No cases required cesarean section after failed vacuum extraction. The incidence of scalp hematoma was higher in the difficult group than in the easy group [28.6% (12/42) vs. 11.7% (14/120), χ2=6.60, P=0.010]. The two groups had no statistically significant differences in the incidence of other neonatal complications. (4) Multivariate logistic regression analysis identified three independent variables associated with difficult vacuum extraction: maternal age, AOP and HPD during contraction. The ROC curve was used to test the predictive value of the multivariate model for difficult vacuum extraction, with an area under the curve of 0.808 (95% CI: 0.734-0.882) ( P<0.001). When the maximum Youden index (0.487) was taken, the sensitivity and specificity of the model in predicting difficult vacuum extraction were 0.762 (95% CI: 0.696-0.828) and 0.725 (95% CI: 0.656-0.794), respectively. Conclusions:AOP and HPD are related to the difficulty of vacuum extraction. The risk of difficult vacuum extraction increases with advanced maternal age, smaller AOP and larger HPD during the contraction phase.
