ISUOG Practice Guidelines: intrapartum ultrasound

The purpose of these Guidelines is to review the published techniques of ultrasound in labor and their practical applications, to summarize the level of evidence regarding the use of ultrasound in labor and to provide guidance to practitioners on when ultrasound in labor is clinically indicated and how the sonographic findings may affect labor management. We do not imply or suggest that ultrasound in labor is a necessary standard of care.

Prediction of labor and delivery by transperineal ultrasound in pregnancies with prelabor rupture of membranes at term

OBJECTIVE

To evaluate whether engagement of the fetal head or cervical length in women with premature rupture of membranes (PROM) at term, are associated with time from PROM to delivery or need for operative delivery.

METHODS

A transperineal ultrasound examination was performed in 152 women with a single live fetus in cephalic presentation after PROM (at > 37 gestational weeks). The shortest distance from the outer bony limit of the fetal skull to the skin surface of the perineum was measured in a transverse view, and the cervical length was measured in a sagittal view. The time from PROM to delivery was tested in a Cox regression analysis with ultrasound measurements, parity, maternal age, body mass index and birth weight as possible predictive factors.

RESULTS

The head-perineal distance was associated with the time from PROM to delivery (log rank test, P < 0.001). Thirty-six hours after PROM, 32% (95% CI, 15-49) of women with a short head-perineal distance (< 45 mm) and 43% (95% CI, 24-62) of women with a long distance (> or = 45 mm) were still in labor. Women with a short head-perineal distance had fewer Cesarean sections, less use of epidural analgesia and a shorter time in active labor, and their babies had a higher pH in the umbilical artery. The measured cervical length was not associated independently with time to delivery.

CONCLUSION

Transperineal ultrasound measurements of fetal head engagement may help clinicians to predict the course of labor in women with PROM.

Is there an increase of postpartum hemorrhage, and is severe hemorrhage associated with more frequent use of obstetric interventions?

OBJECTIVE

To analyze changes in postpartum hemorrhage over a 10-year period from 1998 to 2007, and to explore factors associated with severe hemorrhage.

DESIGN

Retrospective cohort study, prospectively collected information.

SETTING

Stavanger University Hospital, a secondary referral center, Norway.

POPULATION

An unselected population of 41,365 women giving birth at the hospital.

METHODS

We analyzed changes over time in mean postpartum hemorrhage, severe postpartum hemorrhage and associated factors. Estimated blood loss >1,000 ml was defined as severe hemorrhage. Data were collected from the hospital's database.

MAIN OUTCOME MEASURES

Severe postpartum hemorrhage and obstetric interventions.

RESULTS

We observed an increase in severe hemorrhage during the study period. After cesarean sections, the risk of severe hemorrhage was twice the risk of severe hemorrhage after vaginal deliveries (5.9%; 95% CI 5.3-6.6 vs. 2.8%; 95% CI 2.6-2.9). The most important factors associated with severe hemorrhage following vaginal deliveries were twin deliveries (OR 6.8), retained placenta (OR 3.9) and inductions of labor (OR 2.2). For cesarean sections, twin deliveries had the strongest association with severe hemorrhage (OR 3.7) followed by general anesthesia (OR 3.0). Obstetric interventions became more frequent; elective cesarean sections increased from 2.4 to 4.9%, acute cesarean sections from 5.5 to 8.9%, operative vaginal deliveries from 9.3 to 12.5%, inductions of labor from 14.3 to 15.8% and augmentations of labor from 5.8 to 29.3%.

CONCLUSIONS

The incidence of severe postpartum hemorrhage increased, and this may be related to more frequent use of obstetric interventions.

Comparison between ultrasound parameters and clinical examination to assess fetal head station in labor

OBJECTIVE

Several ultrasound parameters, including intrapartum transperineal ultrasound (ITU) head station, angle of progression (AOP), head-perineum distance (HPD) and head-symphysis distance (HSD), have been suggested to assess fetal head station during labor. The aim of this study was to analyze the relationship between these ultrasound parameters and to compare them with digital palpation.

METHODS

We analyzed 106 stored volume dataset pairs that had been acquired at Stavanger University Hospital, Norway, from nulliparous women at term with prolonged first stage of labor. The volumes were acquired using a three-dimensional transducer applied between the labia majora in a mid-sagittal plane and perineally in a transverse plane. Digitally palpated head station and cervical dilatation were also noted. The results were compared using regression and correlation coefficients.

RESULTS

There were good correlations between ITU head station and HPD (r = 0.71), between ITU head station and HSD (r = 0.74) and between HSD and HPD (r = 0.75). Palpated head station showed only moderate correlation with ITU head station (r = 0.52). Cervical dilatation showed a weak correlation with ITU head station (r = 0.30).

CONCLUSION

The ultrasound parameters showed a high degree of correlation with each other, but only moderate correlation to vaginally palpated fetal head station.

Prediction of delivery mode with transperineal ultrasound in women with prolonged first stage of labor

OBJECTIVE

To investigate if fetal head-perineum distance and angle of progression measured with two-dimensional (2D) and three-dimensional (3D) transperineal ultrasound could predict outcome of labor in primiparous women with prolonged first stage of labor.

METHODS

This was a prospective observational study of 110 primiparous women with singleton cephalic presentation at term diagnosed with prolonged first stage of labor. Digital assessment of fetal station was related to the ischial spine. Fetal head descent was measured with transperineal ultrasound as the shortest distance from the fetal head to the perineum, and the angle between the pubic symphysis and the fetal head. Receiver-operating characteristics (ROC) curves were constructed and 2D and 3D data acquisitions were compared. The stored 3D volumes were assessed by an examiner blinded to all other data. Vaginal delivery vs. Cesarean section was the primary outcome.

RESULTS

Cesarean section was performed in 25% of the women. Areas under the ROC curves for prediction of vaginal delivery were 81% (95% confidence interval (CI), 71-91%) (P < 0.01) and 76% (95% CI, 66-87%) (P < 0.01) for fetal head-perineum distance and angle of progression, respectively, as measured by 2D ultrasound and 66% (95% CI, 54-79%) for digital assessment of fetal station (P = 0.01). In 50% of women fetal head-perineum distance was ≤ 40 mm and 93% (95% CI, 83-97%) of them delivered vaginally vs. 18% (95% CI, 5-48%) with distance > 50 mm. In 48% of women the angle of progression was ≥ 110° and 87% (95% CI, 75-93%) of them delivered vaginally vs. 38% (95% CI, 21-57%) with angle < 100°. Results from 2D and 3D acquisitions were similar.

CONCLUSION

Fetal head-perineum distance and angle of progression measured with 2D or 3D ultrasound can predict labor outcome, with similar predictive values for the two techniques.

Ultrasound assessment of fetal head-perineum distance before induction of labor

OBJECTIVES

To evaluate fetal head-perineum distance measured by ultrasound imaging as a predictive factor for induction of labor, and to compare this distance with maternal factors, the Bishop score and ultrasound measurements of cervical length, cervical angle and occiput position.

METHODS

The study included 275 women admitted for induction of labor. The fetal head-perineum distance was measured by transperineal ultrasound imaging as the shortest distance from the outer bony limit of the fetal skull to the skin surface of the perineum. Cervical length and angle was measured by transvaginal ultrasound examination, and fetal head position was assessed by transabdominal ultrasound imaging. The Bishop score was assessed without knowledge of ultrasound measurements. Receiver-operating characteristics (ROC) curves were used for evaluation of the probability of a successful vaginal delivery. The time from induction to delivery was tested using Cox regression analysis with ultrasound measurements, parity and body mass index (BMI) as possible predictive factors.

RESULTS

Areas under the ROC curve for prediction of vaginal delivery were 62% (95% CI, 52-71%) for fetal head-perineum distance (P = 0.03), 61% (95% CI, 51-71%) for cervical length (P = 0.03), 63% (95% CI, 52-74%) for cervical angle (P = 0.02), 61% (95% CI, 52-70%) for Bishop score (P = 0.03) and 60% (95% CI, 51-69%) for BMI (P = 0.05). The Cesarean delivery rate was 22% among nulliparous and 5% among parous women (P < 0.01). Parity, fetal head-perineum distance, cervical length and cervical angle were contributing factors predicting vaginal delivery within 24 h in a Cox regression model. Occiput posterior position had no significant predictive value.

CONCLUSIONS

Fetal head-perineum distance measured by transperineal ultrasound examination can predict vaginal delivery after induction of labor, with a predictive value similar to that of ultrasonographically measured cervical length and the Bishop score. However, we judge none of these methods used alone to be good enough in a clinical setting.

Sonographic prediction of outcome of vacuum deliveries: a multicenter, prospective cohort study

BACKGROUND

Safe management of the second stage of labor is of great importance. Unnecessary interventions should be avoided and correct timing of interventions should be focused. Ultrasound assessment of fetal position and station has a potential to improve the precision in diagnosing and managing prolonged or arrested labors. The decision to perform vacuum delivery is traditionally based on subjective assessment by digital vaginal examination and clinical expertise and there is currently no method of objectively quantifying the likelihood of successful delivery. Prolonged attempts at vacuum delivery are associated with neonatal morbidity and maternal trauma, especially so if the procedure is unsuccessful and a cesarean is performed.

OBJECTIVE

The aim of the study was to assess if ultrasound measurements of fetal position and station can predict duration of vacuum extractions, mode of delivery, and fetal outcome in nulliparous women with prolonged second stage of labor.

STUDY DESIGN

We performed a prospective cohort study in nulliparous women at term with prolonged second stage of labor in 7 European maternity units from 2013 through 2016. Fetal head position and station were determined using transabdominal and transperineal ultrasound, respectively. Our preliminary clinical experience assessing head-perineum distance prior to vacuum delivery suggested that we should set 25 mm for the power calculation, a level corresponding roughly to +2 below the ischial spines. The main outcome was duration of vacuum extraction in relation to ultrasound measured head-perineum distance with a predefined cut-off of 25 mm, and 220 women were needed to discriminate between groups using a hazard ratio of 1.5 with 80% power and alpha 5%. Secondary outcomes were delivery mode and umbilical artery cord blood samples after birth. The time interval was evaluated using survival analyses, and the outcomes of delivery were evaluated using receiver operating characteristic curves and descriptive statistics. Results were analyzed according to intention to treat.

RESULTS

The study population comprised 222 women. The duration of vacuum extraction was shorter in women with head-perineum distance ≤25 mm (log rank test <0.01). The estimated median duration in women with head-perineum distance ≤25 mm was 6.0 (95% confidence interval, 5.2-6.8) minutes vs 8.0 (95% confidence interval, 7.1-8.9) minutes in women with head-perineum distance >25 mm. The head-perineum distance was associated with spontaneous delivery with area under the curve 83% (95% confidence interval, 77-89%) and associated with cesarean with area under the curve 83% (95% confidence interval, 74-92%). In women with head-perineum distance ≤35 mm, 7/181 (3.9%) were delivered by cesarean vs 9/41 (22.0%) in women with head-perineum distance >35 mm (P <.01). Ultrasound-assessed position was occiput anterior in 73%. Only 3/138 (2.2%) fetuses in occiput anterior position and head-perineum distance ≤35 mm vs 6/17 (35.3%) with nonocciput anterior position and head-perineum distance >35 mm were delivered by cesarean. Umbilical cord arterial pH <7.10 occurred in 2/144 (1.4%) women with head-perineum distance ≤35 mm compared to 8/40 (20.0%) with head-perineum distance >35 mm (P < .01).

CONCLUSION

Ultrasound has the potential to predict labor outcome in women with prolonged second stage of labor. The information obtained could guide whether vacuum delivery should be attempted or if cesarean is preferable, whether senior staff should be in attendance, and if the vacuum attempt should be performed in the operating theater.

The frequency of intrapartum caesarean section use with the WHO partograph versus Zhang's guideline in the Labour Progression Study (LaPS): a multicentre, cluster-randomised controlled trial

BACKGROUND

There is an ongoing debate concerning which guidelines and monitoring tools are most beneficial for assessing labour progression, to help prevent use of intrapartum caesarean section (ICS). The WHO partograph has been used for decades with the assumption of a linear labour progression; however, in 2010, Zhang introduced a new guideline suggesting a more dynamic labour progression. We aimed to investigate whether the frequency of ICS use differed when adhering to the WHO partograph versus Zhang's guideline for labour progression.

METHODS

We did a multicentre, cluster-randomised controlled trial at obstetric units in Norway, and each site was required to deliver more than 500 fetuses per year to be eligible for inclusion. The participants were nulliparous women who had a singleton, full-term fetus with cephalic presentation, and who entered spontaneous active labour. The obstetric units were treated as clusters, and women treated within these clusters were all given the same treatment. We stratified these clusters by size and number of previous caesarean sections. The clusters containing the obstetric units were then randomly assigned (1:1) to the control group, which adhered to the WHO partograph, or to the intervention group, which adhered to Zhang's guideline. The randomisation was computer-generated and was done in the Unit of Biostatistics and Epidemiology, Oslo University Hospital, Oslo, Norway, and investigators in this unit had no further involvement in the trial. Our study design did not enable masking of participants or health-care providers, but the investigators who were analysing the data were masked to group allocation. The primary outcome was use of ICS during active labour (cervical dilatation of 4-10 cm) in all participating women. The Labour Progression Study (LaPS) is registered with ClinicalTrials.gov, number NCT02221427.

FINDINGS

Between Aug 1, 2014, and Sept 1, 2014, 14 clusters were enrolled in the LaPS trial, and on Sept 11, 2014, seven obstetric units were randomly assigned to the control group (adhering to the WHO partograph) and seven obstetric units were randomly assigned to the intervention group (adhering to Zhang's guideline). Between Dec 1, 2014, and Jan 31, 2017, 11 615 women were judged to be eligible for recruitment in the trial, which comprised 5421 (46·7%) women in the control group units and 6194 (53·3%) women in the intervention group units. In the control group, 2100 (38·7%) of 5421 women did not give signed consent to participate and 16 (0·3%) women abstained from participation. In the intervention group, 2181 (35·2%) of 6194 women did not give signed consent to participate and 41 (0·7%) women abstained from participation. 7277 (62·7%) of 11 615 eligible women were therefore included in the analysis of the primary endpoint. Of these women, 3305 (45·4%) participants were in an obstetric unit that was randomly assigned to the control group (adhering to the WHO partograph) and 3972 (54·6%) participants were in an obstetric unit that was randomly assigned to the intervention group (adhering to Zhang's guideline). No women dropped out during the trial. Before the start of the trial, ICS was used in 9·5% of deliveries in the control group obstetric units and in 9·3% of intervention group obstetric units. During our trial, there were 196 (5·9%) ICS deliveries in women in the control group (WHO partograph) and 271 (6·8%) ICS deliveries in women in the intervention group (Zhang's guideline), and the frequency of ICS use did not differ between the groups (adjusted relative risk 1·17, 95% CI 0·98-1·40; p=0·08; adjusted risk difference 1·00%, 95% CI -0·1 to 2·1). We identified no maternal or neonatal deaths during our study.

INTERPRETATION

We did not find any significant difference in the frequency of ICS use between the obstetric units assigned to adhere to the WHO partograph and those assigned to adhere to Zhang's guideline. The overall decrease in ICS use that we observed relative to the previous frequency of ICS use noted in these obstetric units might be explained by the close focus on assessing labour progression more than use of the guidelines. Our results represent an important contribution to the discussion on implementation of the new guideline.

FUNDING

Østfold Hospital Trust.

Sonographic prediction of vaginal delivery in prolonged labor: a two-center study

OBJECTIVE

To investigate whether head-perineum distance (HPD) measured by transperineal ultrasound is predictive of vaginal delivery and time remaining in labor in nulliparous women with prolonged first stage of labor and to compare the predictive value with that of angle of progression (AoP).

METHODS

This was a prospective observational study at Stavanger University Hospital, Norway and Addenbrooke's Hospital, Cambridge, UK from January 2012 to April 2013, of nulliparous women with singleton pregnancies with cephalic presentation at term with prolonged first stage of labor. We used transperineal ultrasound to measure HPD (shortest distance between the outer bony limit of the fetal skull and the perineum) and AoP (angle between a line through the long axis of the symphysis and the tangent to the fetal head) and transabdominal ultrasound to classify fetal head position. The main outcomes were vaginal delivery and time remaining in labor.

RESULTS

Of 150 women enrolled, 39 underwent delivery by Cesarean section. The area under the receiver-operating characteristics curve for the prediction of vaginal delivery was 81% (95% CI, 73-89%) using HPD as the test variable and 72% (95% CI, 63-82%) using AoP. HPD was ≤ 40 mm in 84 (56%) women, of whom 77 (92%; 95% CI, 84-96%) delivered vaginally. HPD was > 40 mm in the other 66 (44%) women, of whom 34 (52%; 95% CI, 40-63%) delivered vaginally. AoP was ≥ 110° in 84 of the 145 (58%) in whom this was available and, of these, 74 (88%; 95% CI, 79-93%) delivered vaginally. AoP was < 110° in the other 61 (42%) women, of whom 35 (57%; 95% CI, 45-69%) delivered vaginally. Multivariable logistic regression analysis showed that HPD ≤ 40 mm (odds ratio (OR), 4.92; 95% CI, 1.54-15.80), AoP ≥ 110° (OR, 3.11; 95% CI, 1.01-9.56), non-occiput posterior position (OR, 3.36; 95% CI, 1.24-9.12) and spontaneous onset of labor (OR, 4.44; 95% CI, 1.42-13.89) were independent predictors for vaginal delivery. Both ultrasound methods were predictive for the time remaining in labor.

CONCLUSION

Transperineal ultrasound measurement of HPD and AoP provide important information about the likelihood of vaginal delivery and the time remaining in labor in nulliparous women with prolonged labor.

The sonopartogram: a novel method for recording progress of labor by ultrasound

OBJECTIVES

Progress of labor has hitherto been assessed by digital vaginal examination (VE). We introduce the concept of a non-intrusive ultrasound (US)-based assessment of labor progress (the 'sonopartogram') and investigate its feasibility for assessing cervical dilatation and fetal head descent and rotation.

METHODS

This was a prospective study performed in 20 women in the first stage of labor in two European maternity units. Almost simultaneous assessment of cervical dilatation and fetal head descent and rotation were made by US and digital VE.

RESULTS

The total number of paired US and digital VE assessments was 52, with a median of three per woman. Overall, 5% of sonopartogram parameters were not obtained compared with 18% of conventional digital VE parameters (P < 0.001). Assessment of cervical dilatation was possible in 86.5% of US examinations and 100% of digital VEs (P = 0.02), and dilatation was assessed as being greater by digital VE than by US (mean difference, 1.16 (95% limits of agreement, -0.76, 3.08) cm, r(2) = 0.68, P = 0.01). Fetal head descent was measured in all 52 cases by both methods (r(2) = 0.33, P < 0.001), but correlation between the two was only moderate. Head rotation was obtainable in 98% of US examinations and 46% of digital VEs (P < 0.001), with a mean difference of -3.9° (95% limits of agreement, -144.1°, 136.3°).

CONCLUSION

In this proof-of-concept study, the acquisition of data regarding progress of labor was more successful for the sonopartogram than the conventional partogram. The agreement between digital VE and US was good for cervical dilatation and head rotation but less so for head descent. US assessment of the progress of labor is feasible in most cases.

Simple two-dimensional ultrasound technique to assess intrapartum cervical dilatation: a pilot study

OBJECTIVES

To describe a two-dimensional (2D) ultrasound technique to measure cervical dilatation in labor, and to compare ultrasound with digital measurements.

METHODS

2D transperineal ultrasound was performed in 21 nulliparous women in labor with a singleton fetus in cephalic presentation and cervical dilatation measured before or after a digital vaginal examination. The absolute difference was calculated and Bland-Altman analysis was used to assess the mean difference between digital vaginal examination and ultrasound examination of cervical dilatation. Pearson analysis was used to determine the correlation between digital and ultrasound measurements. Intraclass correlation coefficients (ICCs) with 95% CI were used to evaluate the reliability of the two methods.

RESULTS

Satisfactory quality images of the cervix were obtained in 19 of 21 cases. There was positive correlation between 2D ultrasound measurement of cervical dilatation and digital vaginal examination (Pearson coefficient r = 0.821, n = 19, P < 0.001). Bland-Altman analysis showed a mean difference between digital and ultrasound measurements of 0.08 cm (95% limits of agreement: -1.83 to 2.00) and the mean absolute difference was 1.24 cm. The ICC between the two methods was 0.81 (95% CI, 0.58-0.92).

CONCLUSIONS

Assessment and measurement of cervical dilatation by 2D transperineal ultrasound is feasible, with close agreement shown between the technique and digital vaginal examination. The technique that we describe could represent an important component of a 'sonopartogram' for ultrasound assessment of labor progress.

Prediction of delivery mode by ultrasound-assessed fetal position in nulliparous women with prolonged first stage of labor

OBJECTIVES

To ascertain if fetal head position on transabdominal ultrasound is associated with delivery by Cesarean section in nulliparous women with a prolonged first stage of labor.

METHODS

This was a prospective observational study performed at Stavanger University Hospital, Norway, and Addenbrooke's Hospital, Cambridge, UK, between January 2012 and April 2013. Nulliparous pregnant women with a singleton cephalic presentation at term and prolonged labor had fetal head position assessed by ultrasound. The main outcome was Cesarean section vs vaginal delivery, and secondary outcomes were association of fetal head position with operative vaginal delivery and duration of remaining time in labor.

RESULTS

Fetal head position was assessed successfully by ultrasound examination in 142/150 (95%) women. In total, 19/50 (38%) women with a fetus in the occiput posterior (OP) position were delivered by Cesarean section compared with 16/92 (17%) women with a fetus in a non-OP position (P = 0.01). On multivariable logistic regression analysis, the OP position predicted delivery by Cesarean section with an odds ratio (OR) of 2.9 (95% CI, 1.3-6.7; P = 0.01) and induction of labor with an OR of 2.4 (95% CI, 1.0-5.6; P = 0.05). Fetal head position was not associated with operative vaginal delivery or with remaining time in labor. The agreement between a digital and an ultrasound assessment of OP position was poor (Cohen's kappa = 0.19; P = 0.18).

CONCLUSION

OP fetal head position assessed by transabdominal ultrasound was significantly associated with delivery by Cesarean section.

Outbreak of Campylobacter infection in a subartic community

A presumably waterborne outbreak of Campylobacter jejuni/coli infection in a subarctic community is described. Drinking water supplied to residents was delivered unchlorinated during a 4-week period. No Campylobacter sp. was recovered from the water supply. Three hundred thirty individuals (15% of the 2,200 exposed) became ill. Diarrhoea, abdominal pain, fever, nausea and joint pain occurred in 81%, 30%, 29%, 43% and 21%, respectively. Nine percent reported swelling of joints, and two cases of reactive arthritis occurred. A Campylobacter sp. was isolated from 9 of 33 individuals who became ill and from 1 of 33 healthy controls. All culture-positive individuals, 46% of culture-negative ill persons and 27% of healthy controls were seropositive. All strains recovered had an identical DNA profile.

Fetal Growth and Birth Anthropometrics in Metformin-Exposed Offspring Born to Mothers With PCOS

CONTEXT

Metformin is used in an attempt to reduce pregnancy complications associated with polycystic ovary syndrome (PCOS). Little is known about the effect of metformin on fetal development and growth.

OBJECTIVES

To compare the effect of metformin versus placebo on fetal growth and birth anthropometrics in PCOS offspring compared with a reference population in relation to maternal body mass index (BMI).

DESIGN

Post hoc analysis of a randomized controlled trial.

SETTING

Double-blind, placebo-controlled, multicenter study.

PATIENTS

258 offspring born to mothers with PCOS.

INTERVENTION

2000 mg metformin (n = 131) or placebo (n = 121) from first trimester to delivery.

MAIN OUTCOME MEASURES

Mean abdominal diameter and biparietal diameter (BPD) at gestational weeks 19 and 32. Head circumference (HC), birth length, and weight related to a reference population of healthy offspring, expressed as gestational age- and sex-adjusted z-scores.

RESULTS

Metformin- versus placebo-exposed offspring had larger heads at gestational week 32 (BPD, 86.1 mm versus 85.2 mm; P = 0.03) and at birth (HC, 35.6 cm versus 35.1 cm; P < 0.01). Analyses stratified by maternal prepregnancy BMI, larger heads were observed only among offspring of overweight/obese mothers. Among normal-weight mothers, the effect of metformin compared with placebo was reduced length (z-score = -0.96 versus -0.42, P = 0.04) and weight (z-score = -0.44 versus 0.02; P = 0.03). Compared with the reference population, offspring born to PCOS mothers (placebo group) had reduced length (z-score = -0.40; 95% confidence interval, -0.60 to -0.40), but similar birth weight and HC.

CONCLUSIONS

Metformin exposure resulted in larger head size in offspring of overweight mothers, traceable already in utero. Maternal prepregnancy BMI modified the effect of metformin on offspring anthropometrics. Anthropometrics of offspring born to PCOS mothers differed from those of the reference population.

Assessing the association of oxytocin augmentation with obstetric anal sphincter injury in nulliparous women: a population-based, case-control study

OBJECTIVE

To assess the association of oxytocin augmentation with obstetric anal sphincter injury among nulliparous women.

DESIGN

Population-based, case-control study.

SETTING

Primary and secondary teaching hospital serving a Norwegian region.

POPULATION

15 476 nulliparous women with spontaneous start of labour, single cephalic presentation and gestation ≥37 weeks delivering vaginally between 1999 and 2012.

METHODS

Based on the presence or absence of oxytocin augmentation, episiotomy, operative vaginal delivery and birth weight (<4000 vs ≥4000 g), we modelled in logistic regression the best fit for prediction of anal sphincter injury. Within the modified model of main exposures, we tested for possible confounding, and interactions between maternal age, ethnicity, occiput posterior position and epidural analgaesia.

MAIN OUTCOME MEASURE

Obstetric anal sphincter injury.

RESULTS

Oxytocin augmentation was associated with a higher OR of obstetric anal sphincter injuries in women giving spontaneous birth to infants weighing <4000 g (OR 1.8; 95% CI 1.5 to 2.2). Episiotomy was not associated with sphincter injuries in spontaneous births, but with a lower OR in operative vaginal deliveries. Spontaneous delivery of infants weighing ≥4000 g was associated with a threefold higher OR, and epidural analgaesia was associated with a 30% lower OR in comparison to no epidural analgaesia.

CONCLUSIONS

Oxytocin augmentation was associated with a higher OR of obstetric anal sphincter injuries during spontaneous deliveries of normal-size infants. We observed a considerable effect modification between the most important factors predicting anal sphincter injuries in the active second stage of labour.

Prediction of labour and delivery by ascertaining the fetal head position with transabdominal ultrasound in pregnancies with prelabour rupture of membranes after 37 weeks

PURPOSE

To evaluate the proportion of fetal head rotation from occiput posterior (OP) to occiput anterior (OA) during labour after term prelabour rupture of membranes (PROM), and to study if OP before labour are associated with a higher risk of operative deliveries and a longer duration of labour.

MATERIALS AND METHODS

A transabdominal ultrasound examination was performed in 152 women with PROM after 37 weeks with a single live fetus in cephalic position. The course of labour was compared in women with the fetal head in occiput posterior position or other positions before the start of labour.

RESULTS

Before the start of labour, 40 (26%) fetuses were in occiput posterior position (OP), but 34 (85%) of them rotated to occiput anterior (OA) during labour. Ten (6.6%) fetuses were delivered in OP, and six of them were in OP before the start of labour. There were no statistically significant associations between the head position before the start of labour and the duration from PROM to delivery, induction of labour, use of epidural analgesia, augmentation with oxytocin, operative deliveries, perineal tears, Apgar scores, pH or base excess in the umbilical artery.

CONCLUSIONS

Transabdominal ultrasound examination can determine the fetal head position before the start of labour, but the position of the head did not predict the course of labour, probably because the fetal head may rotate during labour even after PROM.

Agreement between transperineal ultrasound measurements and digital examinations of cervical dilatation during labor

Background

To compare 2D transperineal ultrasound assessment of cervical dilatation with vaginal examination and to investigate intra-observer variability of the ultrasound method.

Methods

A prospective observational study was performed at Skane University Hospital, Lund, Sweden between October 2013 and June 2014. Women with one fetus in cephalic presentation at term had the cervical dilatation assessed with ultrasound and digital vaginal examinations during labor. Inter-method agreement between ultrasound and digital examinations and intra-observer repeatability of ultrasound examinations were tested.

Results

Cervical dilatation was successfully assessed with ultrasound in 61/86 (71 %) women. The mean difference between cervical dilatation and ultrasound measurement was 0.9 cm (95 % CI 0.47–1.34). Interclass correlation coefficient (ICC) was 0.83 (95 % CI 0.72–0.90). Intra-observer repeatability was analysed in 26 women. The intra-observer ICC was 0.99 (95 % CI 0.97–0.99). The repeatability coefficient was ± 0.68 (95 % CI 0.45–0.91).

Conclusion

The mean ultrasound measurement of cervical dilatation was approximately 1 cm less than clinical assessment. The intra-observer repeatability of ultrasound measurements was high.

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.

Descent of fetal head during active pushing: secondary analysis of prospective cohort study investigating ultrasound examination before operative vaginal delivery

OBJECTIVES

To investigate if descent of the fetal head during active pushing is associated with duration of operative vaginal delivery, mode of delivery and neonatal outcome in nulliparous women with prolonged second stage of labor.

METHODS

This was a prospective cohort study of nulliparous women with prolonged second stage of labor, conducted between November 2013 and July 2016 in five European countries. Fetal head descent was measured using transperineal ultrasound. Head-perineum distance (HPD) was measured between contractions and on maximum contraction during active pushing, and the difference between these values (ΔHPD) was calculated. The main outcome was duration of operative vaginal delivery, estimated using survival analysis to calculate hazard ratios (HRs) for vaginal delivery, with values > 1 indicating a shorter duration. HR was adjusted for prepregnancy body mass index, maternal age, induction of labor, augmentation with oxytocin and use of epidural analgesia. Pregnancies were grouped according to ΔHPD quartile, and delivery mode and neonatal outcome were compared between groups.

RESULTS

The study population comprised 204 women. Duration of vacuum extraction was shorter with increasing ΔHPD. Estimated mean duration was 10.0, 9.0, 8.8 and 7.5 min in pregnancies with ΔHPD in the first to fourth quartiles, respectively, and the adjusted HR for vaginal delivery, using increasing ΔHPD as a continuous variable, was 1.04 (95% CI, 1.01-1.08). Mean ΔHPD was 7 mm (range, -10 to 37 mm). ΔHPD was either negative or ≤ 2 mm in the lowest quartile. In this group, 7/50 (14%) pregnancies were delivered by Cesarean section, compared with 8/154 (5%) of those with ΔHPD > 2 mm (P < 0.05). There was no significant association between umbilical artery pH < 7.10 or 5-min Apgar score < 7 and ΔHPD quartile.

CONCLUSION

Minimal or no fetal head descent during active pushing was associated with longer duration of operative vaginal delivery and higher frequency of Cesarean section in nulliparous women with prolonged second stage of labor. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Agreement between two- and three-dimensional transperineal ultrasound methods in assessing fetal head descent in the first stage of labor

OBJECTIVE

To study intraobserver repeatability and intermethod agreement between two- (2D) and three-dimensional (3D) transperineal ultrasound methods in assessing fetal head descent during the first stage of labor.

METHODS

Fetal head descent was measured with transperineal ultrasound as the fetal head-perineum distance and the angle of progression in 106 primiparous women with prolonged first stage of labor. A single obstetrician performed all the scans, and another obstetrician analyzed the acquired 2D images and 3D volumes, blinded to clinical assessments and labor outcome. Intraobserver repeatability and intermethod agreement between 2D and 3D methods were analyzed.

RESULTS

The repeatability coefficient was ± 4.1 mm in 2D acquisitions and ± 1.7 mm in 3D acquisitions of fetal head-perineum distance. The intraclass correlation coefficients (ICC) were 0.94 for 2D and 0.99 for 3D measurements. The angle of progression repeatability coefficients were ± 6.7° using 2D and ± 5.7° using 3D ultrasound and ICCs were 0.91 and 0.94, respectively. The intermethod ICC for fetal head-perineum distance in 2D vs 3D acquisitions was 0.95 and for angle of progression it was 0.93; the intermethod 95% limits of agreement were - 5.8 mm to + 7.2 mm and - 8.9° to + 13.7°, respectively. Cohen's kappa for 2D vs 3D acquisitions was 0.85 using 40 mm as a cut-off level for fetal head-perineum distance and 0.79 using 110° as cut-off level for angle of progression.

CONCLUSIONS

For one ultrasound operator the intraobserver repeatability and agreement between 2D and 3D ultrasound methods in prolonged first stage of labor were good. Given that 2D methods are simpler to learn and can be analyzed quickly online, 2D equipment might therefore be preferred in the labor room.

Maternal body mass index and risk of obstetric, maternal and neonatal outcomes: A cohort study of nulliparous women with spontaneous onset of labor

INTRODUCTION

This study investigates associations between maternal body mass index (BMI) early in pregnancy and obstetric interventions, maternal and neonatal outcomes.

MATERIAL AND METHODS

This is a cohort study of nulliparous women originally included in a cluster randomized controlled trial carried out at 14 Norwegian obstetric units between 2014 and 2017. The sample included 7189 nulliparous women with a singleton fetus, cephalic presentation and spontaneous onset of labor at term, denoted as group 1 in the Ten-Group Classification System. The women were grouped according to the World Health Organization BMI classifications: underweight (BMI <18.5), normal weight (BMI 18.5-24.9), pre-obesity (BMI 25.0-29.9), obesity class I (BMI 30.0-34.9), and obesity classes II and III (BMI ≥35.0). We used binary logistic regression to estimate crude and adjusted odds ratios (ORs) of the interventions and outcomes, with associated 95% confidence intervals (CIs), comparing women in different BMI groups with women of normal weight.

RESULTS

We found an increased risk of intrapartum cesarean section in women of obesity class I and obesity classes II and III, with adjusted OR of 1.70 (95% CI 1.21-2.38) and 2.31 (95% CI 1.41-3.77), respectively. Women in obesity groups had a gradient of risk of epidural analgesia and use of continuous CTG (including STAN), with adjusted OR of 2.39 (95% CI 1.69-3.38) and 3.28 (95% CI 1.97-5.48), respectively. Women in obesity classes II and III had higher risk of amniotomy (adjusted OR = 1.42, 95% CI 1.02-1.96), oxytocin augmentation (adjusted OR = 1.54, 95% CI 1.11-2.15), obstetric anal sphincter injuries (adjusted OR = 2.21, 95% CI 1.01-4.85) and postpartum hemorrhage ≥1000 mL (adjusted OR = 2.20, 95% CI 1.29-3.78). We found a reduced likelihood of spontaneous vaginal delivery for pre-obese women (adjusted OR = 0.85, 95% CI 0.74-0.97) and no associations between maternal BMI and neonatal outcomes.

CONCLUSIONS

Obese women in Ten-Group Classification System group 1 had increased risks of obstetric interventions and maternal complications. There was a gradient of risk for intrapartum cesarean section, with the highest risk for women in obesity classes II and III. No associations between maternal BMI and neonatal outcomes were observed.