Predictors for failure of vacuum-assisted vaginal delivery: a case-control study

Precision of vacuum cup placement and its association with subgaleal hemorrhage and associated morbidity in term neonates

PURPOSE

To evaluate whether the precision of vacuum cup placement is associated with failed vacuum extraction(VE), neonatal subgaleal hemorrhage(SGH) and other VE-related birth trauma.

METHODS

All women with singleton term cephalic fetuses with attempted VE were recruited over a period of 30 months. Neonates were examined immediately after birth and the position of the chignon documented to decide whether the cup position was flexing median or suboptimal. Vigilant neonatal surveillance was performed to look for VE-related trauma, including subgaleal/subdural hemorrhages, skull fractures, scalp lacerations. CT scans of the brain were ordered liberally as clinically indicated.

RESULTS

The VE rate was 5.89% in the study period. There were 17(4.9%) failures among 345 attempted VEs. Thirty babies suffered from subgaleal/subdural hemorrhages, skull fractures, scalp lacerations or a combination of these, giving an incidence of VE-related birth trauma of 8.7%. Suboptimal cup positions occurred in 31.6%. Logistic regression analysis showed that failed VE was associated with a non-occipital anterior fetal head position (OR 3.5, 95% CI 1.22-10.2), suboptimal vacuum cup placement (OR 4.13, 95% CI 1.38-12.2) and a longer duration of traction (OR 8.79, 95% CI 2.13-36.2); while, VE-related birth trauma was associated with failed VE (OR 3.93, 95% CI 1.08-14.3) and more pulls (OR 4.07, 95% CI 1.98-8.36).

CONCLUSION

Suboptimal vacuum cup positions were related to failed VE but not to SGH and other vacuum-related birth trauma. While optimal flexed median cup positions should be most desirable mechanically to effect delivery, such a position does not guarantee prevention of SGH.

Assisted vaginal birth in 21st century: current practice and new innovations

Assisted vaginal birth rates are falling globally with rising cesarean delivery rates. Cesarean delivery is not without consequence, particularly when carried out in the second stage of labor. Cesarean delivery in the second stage is not entirely protective against pelvic floor morbidity and can lead to serious complications in a subsequent pregnancy. It should be acknowledged that the likelihood of morbidity for mother and baby associated with cesarean delivery increases with advancing labor and is greater than spontaneous vaginal birth, irrespective of the method of operative birth in the second stage of labor. In this article, we argue that assisted vaginal birth is a skilled and safe option that should always be considered and be available as an option for women who need assistance in the second stage of labor. Selecting the most appropriate mode of birth at full dilatation requires accurate clinical assessment, supported decision-making, and personalized care with consideration for the woman's preferences. Achieving vaginal birth with the primary instrument is more likely with forceps than with vacuum extraction (risk ratio, 0.58; 95% confidence interval, 0.39-0.88). Midcavity forceps are associated with a greater incidence of obstetric anal sphincter injury (odds ratio, 1.83; 95% confidence interval, 1.32-2.55) but no difference in neonatal Apgar score or umbilical artery pH. The risk for adverse outcomes is minimized when the procedure is conducted by a skilled accoucheur who selects the most appropriate instrument likely to achieve vaginal birth with the primary instrument. Anticipation of potential complications and dynamic decision-making are just as important as the technique for safe instrument use. Good communication with the woman and the birthing partner is vital and there are various recommendations on how to achieve this. There have been recent developments (such as OdonAssist) in device innovation, training, and strategies for implementation at a scale that can provide opportunities for both improved outcomes and reinvigoration of an essential skill that can save mothers' and babies' lives across the world.

Head-to-perineum distance measured transperineally as a predictor of failed midcavity vacuum-assisted delivery

BACKGROUND

During the second stage of labor, in case of a need for a fetal extraction at midcavity, the choice of attempting the procedure between operative vaginal delivery and cesarean delivery is difficult. Moreover, guidelines on this subject are not clear.

OBJECTIVE

This study aimed to identify antenatal and intrapartum parameters associated with a failed midcavity vacuum-assisted delivery and its association with maternal and neonatal adverse outcomes.

STUDY DESIGN

This was a single-center, retrospective, cohort study conducted at a tertiary maternity hospital in France from January 2010 to December 2020. Women with singleton pregnancies under epidural analgesia with nonanomalous cephalic presenting fetuses and gestational ages at ≥37 weeks of gestation, who were submitted to midcavity vacuum-assisted delivery, were included. Following the American College of Obstetricians and Gynecologists definition, midcavity was defined as the presenting part of the fetus (ie, the fetal head) found at stations 0 and +1. For research purposes, all patients were submitted to transperineal ultrasound to evaluate the head-to-perineum distance, however, this measurement did not affect the decision to perform a midcavity vacuum-assisted delivery. The primary outcome of the study was failed midcavity vacuum-assisted delivery leading to cesarean delivery or the use of a different instrument to achieve vaginal delivery.

RESULTS

Overall, 951 cases of midcavity vacuum-assisted delivery were included in this study. Failed midcavity vacuum-assisted delivery occurred in 242 patients (25.4%). Factors independently associated with failed midcavity vacuum-assisted delivery included maternal height (adjusted odds ratio, 0.96; 95% confidence interval, 0.94-0.99; P=.002), duration of the active phase of the first stage of labor (adjusted odds ratio, 1.11; 95% confidence interval, 1.05-1.17; P<.001), nonocciput anterior fetal head position (adjusted odds ratio, 1.47; 95% confidence interval, 1.06-2.04; P=.02), z score of the head-to-perineum distance (adjusted odds ratio, 1.23; 95% confidence interval, 1.05-1.43; P=.01), and birthweight of >4000 g (adjusted odds ratio, 2.04; 95% confidence interval, 1.28-3.26; P=.003). Women submitted to a failed midcavity vacuum-assisted delivery were more likely to have a major postpartum hemorrhage (7.1% vs 2.0%; P<.001), whereas neonates were more likely to have an umbilical artery pH of <7.1 (30.5% vs 19.8%; P=.001), be admitted to the neonatal intensive care unit (9.6% vs 4.7%; P=.005), and have a severe caput succedaneum (14.9% vs 0.7%; P<.001). Subgroup analysis on all patients with a fetal head station of 0 found that the head-to-perineum distance was the only independent variable associated with failed midcavity vacuum-assisted delivery (adjusted odds ratio, 1.66; 95% confidence interval, 1.29-2.12; P<.001). The area under the receiving operating characteristic curve of the head-to-perineum distance in this subgroup population was 0.67 (95% confidence interval, 0.60-0.73; P<.001), and the optimal cutoff point of the head-to-perineum distance measurement discriminating between failed and successful midcavity vacuum-assisted deliveries was 55 mm. It was associated with a 0.90 (95% confidence interval, 0.83-0.95) sensitivity, 0.19 (95% confidence interval, 0.14-0.25) specificity, 0.36 (95% confidence interval, 0.30-0.42) positive predictive value, and 0.80 (95% confidence interval, 0.66-0.90) negative predictive value.

CONCLUSION

Study data showed that a high fetal head station, measured using the head-to-perineum distance, and a nonocciput anterior position of the fetal head are independently associated with failed midcavity vacuum-assisted delivery. The result supported the systematic assessment of the sonographic head station and position before performing a midcavity vacuum-assisted delivery.

Secundiparas following a failed vacuum delivery-factors associated with a successful vaginal delivery: a historical prospective cohort

Background

Few studies have focused on the delivery subsequent to a failed vacuum delivery (failed-VD) in secundiparas. The objective of the current study was to examine the factors associated with a vaginal delivery following a failed-VD.

Methods

An historical prospective cohort. Obstetric characteristics of secundiparas who underwent a planned caesarean delivery (CD) were compared to those who elected a trial of labour (TOLAC) at single medical-centre, throughout 2006–2019. The latter were further analysed to study for factures associated with successful vaginal birth (VBAC).

Results

Among the 115 secundiparas included, 89 (77%) underwent TOLAC. Compared to women who underwent an elective CD, those who underwent TOLAC were younger by a mean of 4 years, were more likely to have conceived spontaneously, and had a more advanced gestation by a mean of 10 days. VBAC was achieved in 62 women (70%). New-borns of women with VBAC had in average a lower birth weight compared to those with failed TOLAC, (-)195 g ± 396 g versus ( +)197 g ± 454 g respectively, P < 0.01. Having a higher neonatal birthweight at P2 by increments of 500 g, 400 g or 300 g was associated with a failed TOLAC; OR of 9.7 (95%CI; 2.3, 40.0), 11.5 (95%CI; 2.8, 46.7) and 4.5 (95%CI; 1.4, 13.9), respectively.

Conclusions

Among secundiparas with a previous CD due to a failed-VD, the absolute difference of neonatal BW was found to be significantly associated with achieving VBAC.

Prospective assessment of vacuum deliveries from midpelvic station in a tertiary care university hospital: Frequency, failure rates, labor characteristics and maternal and neonatal complications

BACKGROUND

Midpelvic vacuum extractions are controversial due to reports of increased risk of maternal and perinatal morbidity and high failure rates. Prospective studies of attempted midpelvic vacuum outcomes are scarce. Our main aims were to assess frequency, failure rates, labor characteristics, maternal and neonatal complications of attempted midpelvic vacuum deliveries, and to compare labor characteristics and complications between successful and failed midpelvic vacuum deliveries.

STUDY DESIGN

Clinical data were obtained prospectively from all attempted vacuum deliveries (n = 891) over a one-year period with a total of 6903 births (overall cesarean section rate 18.2% (n = 1258). Student's t-test, Mann-Whitney U-test or Chi-square test for group differences were used as appropriate. Odds ratios and 95% confidence intervals are given as indicated. The uni- and multivariable analysis were conducted both as a complete case analysis and with a multiple imputation approach. A p-value of <0.05 was considered statistically significant.

RESULTS

Attempted vacuum extractions from midpelvic station constituted 36.7% (n = 319) of all attempted vacuum extractions (12.9% (n = 891) of all births). Of these 319 midpelvic vacuum extractions, 11.3% (n = 36) failed and final delivery mode was cesarean section in 86.1% (n = 31) and forceps in the remaining 13.9% (n = 5). Successful completion of midpelvic vacuum by 3 pulls or fewer was achieved in 67.1%. There were 3.9% third-degree and no fourth-degree perineal tears. Cup detachments were associated with a significantly increased failure rate (adjusted OR 6.13, 95% CI 2.41-15.56, p< 0.001).

CONCLUSION

In our study, attempted midpelvic vacuum deliveries had relatively low failure rate, the majority was successfully completed within three pulls and they proved safe to perform as reflected by a low rate of third-degree perineal tears. We provide data for nuanced counseling of women on vacuum extraction as a second stage delivery option in comparable obstetric management settings with relatively high vacuum delivery rates and low cesarean section rates.

Antepartum ultrasound prediction of failed vacuum-assisted operative delivery: a prospective cohort study

BACKGROUND

Failed vacuum-assisted delivery (VD) is associated with increased risk of maternal perineal trauma and neonatal morbidity. Knowledge of the risk factors related to failed VD is essential in the clinical decision-making.

OBJECTIVE

To elucidate the strength of association and the predictive accuracy of different ante-partum ultrasound parameters in predicting the risk of failed VD prior to the onset of Labor and to test the diagnostic performance of a multiparametric model including pregnancy and Labor characteristics, ante and intra-partum ultrasound in anticipating failed VD.

STUDY DESIGN

Prospective study of consecutive singleton pregnancies complicated by VD undergoing a dedicated ultrasound assessment at 36-38 weeks of gestation. Head circumference (HC), estimated fetal weight (EFW) and subpubic angle and (SPA) were recorded before the onset of Labor. At the time of the VD, occiput position, head perineum distance (HPD) and angle of progression (AOP) were also recorded. Multivariate logistic regression and area under the curve (AUC) analyses were used to explore the strength of association and test the diagnostic accuracy of different maternal, Labor and ultrasound characteristics in predicting g failed VD.

RESULTS

Four hundred eight pregnancies with successful and 26 with failed VD were included in the analysis. Fetuses experiencing failed VD had a larger HC (1.21 versus 1.07 MoM; p = .0001), a higher EFW z-value (0.56 versus 0.33 z values; p = .002) and a narrower SPA (114 versus 122 p = .0001) compared to those having a successful VD. At multivariable logistic regression analysis, maternal height (aOR 0.89 95% CI 0.76-0.98), nulliparity (aOR: 1.14 95% CI 1.06-1.36), HC MoM (aOR: 1.24 95% CI 1.13-1.55) and SPA angle (aOR: 0.82 95% CI 0.67-0.95), but not EFW (p = .08) were independently associated with failed VD. When intrapartum ultrasound variables were added to the multivariate model, fetal occipital position (aOR: 1.45 95th CI 1.11-1.99) and HPD (aOR: 0.77 95th CI 0.44-0.96) were independently associated with failed VD. A multiparametric model integrating pregnancy and Labor characteristics and ante-partum ultrasound variables had an AUC of 0.837 (95% CI 0.797-0.876) for the prediction of failed VE. The addition of intra-partum ultrasound variables to the prediction model, improved the accuracy for failed VD provided by maternal and antepartum ultrasound characteristics with an AUC of 0.913 (0.888-0.937).

CONCLUSION

Antepartum prediction of failed VD is feasible. HC, SPA but not EFW are independently associated and predictive of failed VD. Adding these variables to a multiparametric model including maternal and intrapartum ultrasound parameters improves the diagnostic accuracy for failed VD.

Perinatal factors related to pregnancy and childbirth satisfaction: a prospective cohort study

BACKGROUND

Satisfaction of pregnancy and childbirth is an important quality measure of maternity care. Satisfaction questionnaires generally result in high scores. However, it has been argued that dissatisfaction relies on a different construct. In response to a worldwide call for obstetric care that is more woman-centered, we identified and described the contributors to suboptimal satisfaction with pregnancy and childbirth.

METHODS

A prospective subcohort of 739 women from a larger cohort (Expect Study I, n = 2614) received a pregnancy and childbirth satisfaction questionnaire. Scores were transformed to a binary outcome whereby a score <100 points corresponded with less satisfied women. We performed a multiple logistic regression analysis to define independent perinatal factors related to suboptimal satisfaction.

RESULTS

Decreased perceived personal well-being, antenatal anxiety, and obstetrician-led care during labor were all independently associated with suboptimal pregnancy and childbirth satisfaction. No difference in satisfaction was found between antenatal care led by a midwife or an obstetrician, but midwife-led antenatal care reduced the odds of suboptimal satisfaction compared to women who were transferred to an obstetrician in the antenatal period. Antenatal anxiety was experienced by 25% of all women and is associated with decreased satisfaction scores.

DISCUSSION

Screening and treatment of women suffering from anxiety might improve pregnancy and childbirth satisfaction, but further research is necessary. Women's birthing experience may improve by reducing unnecessary secondary obstetric care.

Comparison of a practice-based versus theory-based training program for conducting vacuum-assisted deliveries: a randomized-controlled trial

PURPOSE

Vacuum-assisted deliveries (VAD) are complex procedures that require training and experience to be performed proficiently. We aimed to evaluate if a more resource intensive practice-based training program for conducting VAD is more efficient compared to a purely theory-based training program, with respect to immediate training effects and persistence of skills 4-8 weeks after the initial training.

METHODS

In this randomized-controlled study conducted in maternity staff, participants performed a simulated low-cavity non-rotational vacuum delivery before (baseline test) and immediately after the training (first post-training test) as well as 4-8 weeks thereafter (second post-training test). The study's primary endpoint was to compare training effectiveness between the two study groups using a validated objective structured assessment of technical skills (OSATS) rating scale.

RESULTS

Sixty-two participants were randomized to either the theory-based group (n = 31) or the practice-based group (n = 31). Total global and specific OSATS scores, as well as distance of cup application to the flexion point improved significantly from baseline test to the first post-training test in both groups (p_all < 0.007). Skill deterioration after 4-8 weeks was only found in the theory-based group, whereas skills remained stable in the practice-based group.

CONCLUSION

A practice-based training program for conducting VAD results in comparable immediate improvement of skills compared to a theory-based training program, but the retention of skills 4-8 weeks after training is superior in a practice-based program. Future studies need to evaluate, whether VAD simulation training improves maternal and neonatal outcome after VAD.

Epidural analgesia and vacuum-assisted delivery in primiparous women: maternal and neonatal outcomes

OBJECTIVE

We aimed to evaluate the effect of epidural analgesia (EA) on maternal and neonatal outcomes.

METHODS

We conducted a retrospective cohort database study on primiparous women who underwent a vacuum-assisted delivery (VAD) trial between 2005 and 2019 at a university-affiliated tertiary medical center. We compared women with and without the standard "one protocol" patient-controlled EA. The primary outcome was VAD failure. Secondary outcomes were maternal and neonatal morbidities. We performed univariate analysis, followed by multivariable logistic regression analysis to control for potential confounders. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated.

RESULTS

Overall, 7042 primiparous women attempted VAD during the study period; 6238 (88.3%) and 804 (11.7%) women used and did not use EA, respectively. The VAD failure rate was significantly lower among women with than without EA use (2.5% vs. 4.2%, respectively, p < .01). On multivariable analysis, EA use was found to reduce the VAD failure rate (aOR, 0.05; 95% CI [0.01-0.49], p = .01). Notably, EA use was not associated with an increased rate of any maternal or neonatal adverse outcome (aOR, 1.01; 95% CI [0.8-1.27], p = .95 or aOR, 1.14 95% CI [0.89-1.45], p = .3, respectively).

CONCLUSIONS

EA use in primiparous women is associated with lower rates of VAD failure without an increase in adverse maternal or neonatal outcomes.

Comparison of Multivariable Logistic Regression and Other Machine Learning Algorithms for Prognostic Prediction Studies in Pregnancy Care: Systematic Review and Meta-Analysis

Background

Predictions in pregnancy care are complex because of interactions among multiple factors. Hence, pregnancy outcomes are not easily predicted by a single predictor using only one algorithm or modeling method.

Objective

This study aims to review and compare the predictive performances between logistic regression (LR) and other machine learning algorithms for developing or validating a multivariable prognostic prediction model for pregnancy care to inform clinicians’ decision making.

Methods

Research articles from MEDLINE, Scopus, Web of Science, and Google Scholar were reviewed following several guidelines for a prognostic prediction study, including a risk of bias (ROB) assessment. We report the results based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Studies were primarily framed as PICOTS (population, index, comparator, outcomes, timing, and setting): Population: men or women in procreative management, pregnant women, and fetuses or newborns; Index: multivariable prognostic prediction models using non-LR algorithms for risk classification to inform clinicians’ decision making; Comparator: the models applying an LR; Outcomes: pregnancy-related outcomes of procreation or pregnancy outcomes for pregnant women and fetuses or newborns; Timing: pre-, inter-, and peripregnancy periods (predictors), at the pregnancy, delivery, and either puerperal or neonatal period (outcome), and either short- or long-term prognoses (time interval); and Setting: primary care or hospital. The results were synthesized by reporting study characteristics and ROBs and by random effects modeling of the difference of the logit area under the receiver operating characteristic curve of each non-LR model compared with the LR model for the same pregnancy outcomes. We also reported between-study heterogeneity by using τ² and I².

Results

Of the 2093 records, we included 142 studies for the systematic review and 62 studies for a meta-analysis. Most prediction models used LR (92/142, 64.8%) and artificial neural networks (20/142, 14.1%) among non-LR algorithms. Only 16.9% (24/142) of studies had a low ROB. A total of 2 non-LR algorithms from low ROB studies significantly outperformed LR. The first algorithm was a random forest for preterm delivery (logit AUROC 2.51, 95% CI 1.49-3.53; I²=86%; τ²=0.77) and pre-eclampsia (logit AUROC 1.2, 95% CI 0.72-1.67; I²=75%; τ²=0.09). The second algorithm was gradient boosting for cesarean section (logit AUROC 2.26, 95% CI 1.39-3.13; I²=75%; τ²=0.43) and gestational diabetes (logit AUROC 1.03, 95% CI 0.69-1.37; I²=83%; τ²=0.07).

Conclusions

Prediction models with the best performances across studies were not necessarily those that used LR but also used random forest and gradient boosting that also performed well. We recommend a reanalysis of existing LR models for several pregnancy outcomes by comparing them with those algorithms that apply standard guidelines.

Trial Registration

PROSPERO (International Prospective Register of Systematic Reviews) CRD42019136106; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=136106

Pregnancy outcome after cesarean section following a failed vacuum attempt

OBJECTIVE

To compare the pregnancy outcome of women who underwent cesarean section in the second stage of labor, with or without a vacuum extraction attempt.

METHODS

A retrospective cohort study of women who underwent a cesarean section during the second stage of labor in a single tertiary university-affiliated medical center (2012-2019). Pregnancy outcome was compared for women who underwent cesarean section following a failed vacuum extraction to women who had cesarean section during the second stage of labor with no vacuum extraction attempt. Neonatal outcomes included umbilical artery pH less than 7.1, Apgar at 5 min < 7, hypoxemic ischemic encephalopathy and NICU admission. Maternal outcomes included duration of hospitalization, need for blood transfusion and need for re-surgery in 45 days.

RESULTS

Overall, 88,375 women delivered during the study period. Of them, 120 women had a cesarean section following a failed vacuum (study group). Another 551 women underwent a cesarean section in the second stage of labor without a VE attempt (control group). The groups were similar with regard to obstetrical and demographic characteristics. The rates of umbilical artery pH < 7.1 (17.50% vs 6.53%, p < .001), NICU admission (13.33% vs 2.90%, p < .001), hypoxemic ischemic encephalopathy (5.83% vs 0.18%, p < .001) and epicranial sub-aponeurotic hemorrhage (16.67% vs 2.18%, p < .001) were significantly higher in the study group. No significant differences were found in maternal outcomes. In a sub-analysis including only labor with reassuring fetal heart tracing, failed vacuum attempt was associated with higher rate of NICU admission and epicranial hemorrhage (16.67% vs 3.13%, p = .009, 27.78% vs. 3.41, p = .001, respectively).

CONCLUSION

Failed vacuum attempt is associated with a significant increased neonatal morbidity, but not increased maternal morbidity.

Vacuum extraction for non-rotational and rotational assisted vaginal birth

Vacuum-assisted birth is a safe mode of birth in the presence of a skilled provider. Vacuum extraction can avoid prolonged second stage of labour, birth asphyxia in the presence of foetal distress or maternal pushing where contraindicated. Vacuum-assisted births - particularly those in midpelvic rotational births - have been increasingly traded for caesarean births, although the latter are generally associated with potentially a greater risk to women and (future) children. In this article, (contra)indications and the basics of vacuum technique are elaborated. A specific section is dedicated to vacuum extraction for rotational birth. If these techniques are known, trained and practiced by obstetric care givers, then vacuum extraction has tremendous potential to make childbirth safer.

Randomised Italian Sonography for occiput POSition Trial Ante vacuum (R.I.S.POS.T.A.)

OBJECTIVE

To assess whether sonographic diagnosis of fetal head position before instrumental vaginal delivery can reduce the risk of failed vacuum extraction and improve delivery outcome.

METHODS

Randomised Italian Sonography for occiput POSition Trial Ante vacuum (R.I.S.POS.T.A.) is a randomized controlled trial of term (37 + 0 to 41 + 6 weeks' gestation) singleton pregnancies with cephalic presentation requiring instrumental delivery by vacuum extraction, which was conducted between April 2014 and June 2017 and involved 13 Italian maternity hospitals. Patients were randomized to assessment of fetal head position before attempted instrumental delivery by either vaginal examination (VE) alone or VE plus transabdominal sonography (TAS). Primary outcome was incidence of emergency Cesarean section due to failed vacuum extraction. A sample size of 653 women per group was planned to compare the primary outcome between the two groups. The sample size estimation was based on the hypothesis that the risk of failed vacuum delivery in the VE group would be 5% and that ultrasound assessment of fetal position prior to vacuum extraction would decrease this risk to 2%.

RESULTS

On interim analysis, the trial was stopped for futility. During this period, 222 women were randomized and 221 were included in the final data analysis, of whom 132 (59.7%) were randomized to evaluation of fetal head position by VE only and 89 (40.3%) to assessment by VE plus TAS prior to vacuum extraction. No significant differences were observed between the two groups with respect to incidence of emergency Cesarean section due to failed instrumental delivery and other maternal and fetal outcomes. Women randomized to assessment by VE plus TAS showed higher incidence of non-occiput anterior position of the fetal head at randomization and lower incidence of incorrect diagnosis of occiput position compared with women undergoing assessment by VE alone. A higher rate of episiotomy was noted in the women undergoing both VE and TAS compared with those in the VE-only group.

CONCLUSIONS

Our prematurely discontinued randomized controlled trial did not demonstrate any benefit in terms of reduced risk of failed instrumental delivery or maternal and fetal morbidity in women undergoing sonographic assessment of fetal head position prior to vacuum extraction. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Strategies to reduce and maintain low perinatal mortality in resource-poor settings - Findings from a four-decade observational study of birth records from a large public maternity hospital in Papua New Guinea

BACKGROUND

In many low- to middle-income countries (LMIC) assisted vaginal birth rates have fallen, while caesarean section (CS) rates have increased, with potentially deleterious consequences for maternal and perinatal mortality.

AIMS

To review birth mode and perinatal mortality in a large LMIC hospital with strict labour management protocols and expertise in vacuum extraction.

MATERIALS AND METHODS

We conducted a retrospective observational study at Port Moresby General Hospital in Papua New Guinea. Birth registers from 1977 to 2015 (39 years) were reviewed. Overall and modified (fresh stillbirths and early neonatal deaths ≥500 g) perinatal mortality rates (PMRs) were calculated by birthweight/birth mode.

RESULTS

There were 365 056 births (5215 in 1977; 14 927 in 2015), of which 14 179 (3.9%) were vacuum extractions, 609 (0.2%) forceps births and 14 747 (4.4%) CS (increase from 2% to 5%). The failure rate of vacuum extraction was 2.5% (range 0.5-5.4%). Symphysiotomy was employed for 184 births. From 1989 to 2015, the modified mean PMR for babies ≥2500 g was 8.1/1000 births (range 5.6-12.1; 6.9 in 2015), 9.1/1000 for babies ≥1500 g (7.3-14.8; 9.1 in 2015) and 7.5/1000 (0-21.7; 9.0 in 2015) for vacuum extractions (98% were ≥2500 g). The overall PMR for these years was 29.7/1000 births.

CONCLUSIONS

In an LMIC with rapidly increasing birth numbers a comparatively low PMR can be achieved while maintaining low CS rates. This may be in part accomplished through strict use of second-stage protocols, perinatal audit, and supportive training that promotes judicious and proficient use of vacuum extraction and CS.

Fetal rotation during vacuum extractions for prolonged labor: a prospective cohort study

INTRODUCTION

The aim of the study was to investigate fetal head rotation during vacuum extraction.

MATERIAL AND METHODS

We conducted a prospective cohort study from November 2013 to July 2016 in seven European hospitals. Fetal head position was determined with transabdominal or transperineal ultrasound and categorized as occiput anterior (OA), occiput transverse (OT) or occiput posterior (OP) position. Main outcome was the proportion of fetuses rotating during vacuum extraction. Secondary outcomes were conversion of delivery method, duration of vacuum extraction, umbilical artery pH <7.10 and agreement between clinical and ultrasound assessments.

RESULTS

The study population comprised 165 women. During vacuum extraction 117/119 (98%) remained in OA and two fetuses rotated to OP position. Rotation from OT to OA position occurred in 14/19 (74%) and to OP position in 5/19 (26%). Rotation from OP to OA position occurred in 15/25 (60%), and 10/25 (40%) fetuses remained in OP position. Delivery information was missing in two cases. The conversion rate from vacuum extraction to cesarean section or forceps was 10% in the OA group vs. 23% in the non-OA group; p < 0.05. The estimated duration of vacuum extraction was significantly shorter in OA fetuses, 7 min vs. 10 min (log rank test p < 0.01). There was no significant difference in umbilical artery pH < 7.10 between OA and non-OA position. Cohens Kappa of agreement between clinical and ultrasound assessments was 0.42 (95% CI 0.26-0.57).

CONCLUSION

Most fetuses in OP or OT positions rotated to OA position during vacuum extraction, but the proportion of failed vacuum extractions remained high.

Vacuum extraction failure is associated with a large head circumference

Objective: To determine whether large head circumference increases the risk of vacuum extraction failure. Study design: This EMR-based study included all attempted vacuum extractions performed in a tertiary center between January 2010 and June 2015. All term singleton live births were eligible. Cases were divided into four groups: head circumference ≥90th percentile both with birth weight ≥90th percentile and <90th percentile and fetal head circumference <90th percentile with birth weight ≥90th and <90th percentile. Risk of failed vacuum extraction was compared among these groups. Other neonatal and maternal parameters were also evaluated as potential risk factors. Multinomial multivariable regression provided adjusted odds ratio for vacuum extraction failure while controlling for potential confounders. Results: During the study period, 48,007 deliveries met inclusion criteria, of which 3835 had an attempt at vacuum extraction. We identified 215 (5.6%) cases of vacuum extraction failure. The adjusted odds ratios (aOR) for vacuum extraction failure in cases of large fetal head circumference was 2.31 (95%CI, 1.7-3.15, p < .001). Primiparity, prolonged second stage and occipito-posterior presentation were also found to be significant risk factors for failed vacuum extraction. Comments: In this study, we found that large head circumference was associated with vacuum extraction failure rather than high birth weight.