Randomised controlled trial of magnetic-resonance pelvimetry in breech presentation at term

Mechanics of vaginal breech birth: Factors influencing obstetric maneuver rate, duration of active second stage of labor, and neonatal outcome

BACKGROUND

We investigated possible parameters that could predict the need for obstetric maneuvers, the duration of the active second stage of labor (i.e., the duration of active pushing), and short-term neonatal outcome in vaginal breech births.

MATERIALS AND METHODS

We performed a retrospective analysis of 268 successful singleton vaginal breech births in women without previous vaginal births from January 2015 to August 2022. Multivariable regression was used to investigate associations between maternal and fetal characteristics (including antepartum magnetic resonance (MR) pelvimetry) with obstetric maneuvers, the duration of active second stage of labor, pH values, and admission to the neonatal unit. Models for the prediction of obstetric maneuvers were built and internally validated.

RESULTS

Obstetric maneuvers were performed in a total of 130 women (48.5%). A total of 32 neonates (11.9%) had to be admitted to the neonatal unit. The intertuberous distance (ITD) (p < 0.001), epidural analgesia (p < 0.001), and birthweight (p = 0.026) were associated with the duration of active second stage of labor. ITD (p = 0.028) and birthweight (p = 0.011) were also independently associated with admission to the neonatal unit, while pH values below 7.10 dropped significantly (p = 0.0034) if ITD was ≥13 cm. Furthermore, ITD (p < 0.001) and biparietal diameter (p = 0.002) were independent predictors for obstetric maneuvers.

CONCLUSIONS

ITD is independently associated with the duration of active second stage of labor. Thus, it can predict suboptimal birth mechanics in the last stage of birth, which may lead to the need for obstetric maneuvers, lower arterial pH values, and admission to the neonatal unit. Consequently, MR pelvimetry gives additional information for practitioners and birthing people preferring a vaginal breech birth.

Novel Three-Dimensional Body Scan Anthropometry versus MR-Pelvimetry for Vaginal Breech Delivery Assessment

In this prospective, monocentric study, we investigated the potency of a novel three-dimensional (3D) body scanner for external pelvic assessment in birth planning for intended vaginal breech delivery. Between April 2021 and June 2022, 73 singleton pregnancies with intended vaginal birth from breech presentation (>36.0 weeks of gestation) were measured using a pelvimeter by Martin, a three-dimensional body scanner, and MR-pelvimetry. Measures were related to vaginal birth and intrapartum cesarean section. A total of 26 outer pelvic dimensions and 7 inner pelvic measurements were determined. The rate of successful vaginal breech delivery was 56.9%. The AUC (area under the curve) of the obstetric conjugate (OC) measured by MRI for predicting the primary outcome was 0.62 (OR 0.63; p = 0.22), adjusted for neonatal birth weight 0.66 (OR 0.60; p = 0.19). Of the 22 measured 3D body scanner values, the ratio of waist girth to maternal height showed the best prediction (AUC = 0.71; OR 1.27; p = 0.015). The best predictive pelvimeter value was the distantia spinarum with an AUC of 0.65 (OR = 0.80). The 3D body scanner technique is at least equal to predict successful vaginal breech delivery compared to MRI diagnostics. Further large-scale, prospective studies are needed to verify these results.

Predictive Value of MRI Pelvimetry in Vaginal Delivery and Its Practicability in Prolonged Labour-A Prospective Cohort Study

BACKGROUND

Pelvic dimensions are crucial variables in the labour process. We used magnetic resonance imaging (MRI) pelvimetry to predict the probability of vaginal delivery and distinguish the cephalopelvic disproportion risk in women with prolonged active labour.

METHODS

This prospective cohort study enrolled term nulliparous women willing to undergo MRI pelvimetry and a trial of labour. A nomogram, with vaginal birth as the outcome, was developed and evaluated by calibration curve and decision curve analyses. The pairwise association between maternal and fetal parameters and a prolonged first stage of labour was quantified.

RESULTS

Head circumference (HC), abdominal circumference (AC), intertuberous distance (ITD), interspinous diameter (ISD), and body mass index (BMI) were introduced to develop a nomogram with good diagnostic performance (area under the curve = 0.799, sensitivity = 83%, and specificity = 73%). The cephalopelvic index of diameter (CID) in 54 women with a prolonged first stage of labour was much smaller in those who delivered via cesarean section compared with those who delivered vaginally (18.09 ± 1.14 vs. 21.29 ± 1.06; p = 0.046).

CONCLUSIONS

An MRI pelvimetry-based nomogram may predict the probability of vaginal delivery. Practitioners should reassess the pelvimetry parameters to decide whether the trial of labour should be continued if it is prolonged.

Magnetic resonance imaging in late pregnancy to improve labour and delivery outcomes - a systematic literature review

BACKGROUND

Magnetic resonance imaging (MRI) provides excellent soft tissue visualisation which may be useful in late pregnancy to predict labour outcome and maternal/neonatal birth trauma.

OBJECTIVE

To study if MRI in late pregnancy can predict maternal and neonatal outcomes of labour and birth.

METHODS

Systematic review of studies that performed MRI in late pregnancy or immediately postpartum. Studies were included if they imaged maternal pelvic or neonatal structures and assessed birth outcome. Meta-analysis was not performed due to the heterogeneity of studies.

RESULTS

Eighteen studies were selected. Twelve studies explored the value of MRI pelvimetry measurement and its utility to predict cephalopelvic disproportion (CPD) and vaginal breech birth. Four explored cervical imaging in predicting time interval to birth. Two imaged women in active labour and assessed mouldability of the fetal skull. No marker of CPD had both high sensitivity and specificity for predicting labour outcome. The fetal pelvic index yielded sensitivities between 59 and 60%, and specificities between 34 to 64%. Similarly, although the sensitivity of the cephalopelvic disproportion index in predicting labour outcome was high (85%), specificity was only 56%. In women with breech presentation, MRI was demonstrated to reduce the rates of emergency caesarean section from 35 to 19%, and allowed better selection of vaginal breech birth. Live birth studies showed that the fetal head undergoes a substantial degree of moulding and deformation during cephalic vaginal birth, which is not considered during pelvimetry. There are conflicting studies on the role of MRI in cervical imaging and predicting time interval to birth.

CONCLUSION

MRI is a promising imaging modality to assess aspects of CPD, yet no current marker of CPD accurately predicts labour outcome. With advances in MRI, it is hoped that novel methods can be developed to better identify individuals at risk of obstructed or pathological labour. Its role in exploring fetal head moulding as a marker of CPD should be further explored.

Magnetic Resonance Imaging-Based Nomogram to Antenatal Predict Cesarean Delivery for Cephalopelvic Disproportion in Primiparous Women

BACKGROUND

Cephalopelvic disproportion (CPD)-related obstructed labor is associated with maternal and neonatal morbidity and mortality. Accurate prediction of whether a primiparous woman is at high risk of an unplanned cesarean delivery would be a major advance in obstetrics.

PURPOSE

To develop and validate a predictive model assessing the risk of cesarean delivery in primiparous women based on MRI findings.

STUDY TYPE

Prospective.

POPULATION

A total of 150 primiparous women with clinical findings suggestive of CPD.

FIELD STRENGTH/SEQUENCE

T1-weighted fast spin-echo sequences, single-shot fast spin-echo (SSFSE) T2-weighted sequences at 1.5 T.

ASSESSMENT

Pelvimetry and fetal biometry were assessed independently by two radiologists. A nomogram model combined that the clinical and MRI characteristics was constructed.

STATISTICAL TESTS

Univariable and multivariable logistic regression analyses were applied to select independent variables. Receiver operating characteristic (ROC) analysis was performed, and the discrimination of the model was assessed by the area under the curve (AUC). Calibration was assessed by calibration plots. Decision curve analysis was applied to evaluate the net clinical benefit. A P value below 0.05 was considered to be statistically significant.

RESULTS

In multivariable modeling, the maternal body mass index (BMI) before delivery, bilateral femoral head distance, obstetric conjugate, fetal head circumference, and fetal abdominal circumference was significantly associated with the likelihood of cesarean delivery. The discrimination calculated as the AUC was 0.838 (95% confidence interval [CI]: 0.774-0.902). The sensitivity and specificity of the nomogram model were 0.787 and 0.764, and the positive predictive and negative predictive values were 0.696 and 0.840, respectively. The model demonstrated satisfactory calibration (calibration slope = 0.945). Moreover, the decision curve analysis proved the superior net benefit of the model compared with each factor included.

DATA CONCLUSION

Our study might provide a nomogram model that could identify primiparous women at risk of cesarean delivery caused by CPD based on MRI measurements.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 2.

[Impact of a service protocol on the practice of vaginal delivery of breech presentations at term]

OBJECTIVES

The delivery of breech presentations remains controversial. Our study analysed the impact of a service protocol on the proportion of planned vaginal delivery and its success. Immediate neonatal morbidity and factors that may influence the success of vaginal delivery were studied.

METHODS

Retrospective study, between 2009 and 2020 at the CHRU of Limoges, type 3 maternity hospital, on patients with a breech foetus at term. The proportion of planned vaginal delivery and the rate of effective vaginal delivery were compared before/after 2015. Neonatal morbidity was compared for planned vaginal delivery and planned cesarean delivery groups.

RESULTS

We included 923 patients. The rate of planned vaginal delivery was significantly higher after 2015 from 5.2% to 19% (P<0.001), with a success rate increasing from 60% to 82.1% (P=0.06). The rate of vaginal breech deliveries significantly increased from 3.8% to 17% (P<0.001). We found significantly more newborns with moderate acidosis when a vaginal delivery was attempted (P<0.001). The success of vaginal delivery was correlated to the Magnin index (P=0.044), to gestational age (P=0.037), and to multiparity (OR 3.78 95% CI [1.42-10.03] P=0.006).

CONCLUSION

Our study demonstrates the benefits of setting up a service protocol for the practice of breech vaginal delivery.

Asymmetric pelvis and term breech presentation: is planned vaginal delivery still a safe option?

PURPOSE

To evaluate the obstetrical prognosis of term breech delivery in case of asymmetric pelvis.

METHODS

An observational, comparative, retrospective, bi-centric study of 559 patients who had a computer tomography pelvimetry prior to delivery of a term breech presentation was conducted between August 2013 and August 2019. Patients with an attempted vaginal delivery were divided into two groups: a group of asymmetric pelvis (AP) when the difference between the lengths of both oblique diameters was ≥ 1 cm and a group of symmetric pelvis (SP) when the two oblique diameters differed by < 1 cm. The primary outcome was the rate of vaginal delivery. Secondary outcomes were a composite variable of neonatal and maternal morbidity and mortality.

RESULTS

Of the 370 patients who attempted a vaginal breech delivery, 8% (n = 29) had an AP and 92% (n = 341) had a SP. In the AP group, the vaginal delivery rate was higher (93% versus 78%, p = 0.05). There was no statistically significant difference in neonatal (3% versus 1% in the AP and SP groups, respectively, p = 0.4) and maternal (17% versus 23% in the AP and SP groups, respectively, p = 0.5) morbidity and mortality.

CONCLUSION

When a pelvimetry is performed before an attempt of vaginal breech delivery, a difference of less than two centimetres between both oblique diameters does not seem to reduce the rate of vaginal birth and is not an indication for an elective caesarean section.

Management of Breech Presentation: A Comparison of Four National Evidence-Based Guidelines

OBJECTIVE

The management of breech presentation may improve perinatal outcomes. The aim of this study was to synthesize and compare published evidence of four national guidelines on breech presentation.

STUDY DESIGN

A descriptive review of four recently published national guidelines on breech presentation and external cephalic version (ECV) was conducted: Royal College of Obstetricians and Gynaecologists guideline on "External Cephalic Version and Reducing the Incidence of Term Breech Presentation" and "Management of Breech Presentation", American College of Obstetricians and Gynecologists guideline on "External Cephalic Version" and "Mode of Term Singleton Breech Delivery," Society of Obstetricians and Gynaecologists of Canada guideline on "Vaginal Delivery of Breech Presentation" and the Royal Australian and New Zealand College of Obstetricians and Gynaecologists guideline on "Management of breech presentation at term."

RESULTS

Regarding ECV, there is no recommendation by the SOGC, whereas all other national guidelines recommend this technique. Regarding breech vaginal delivery, there are limited recommendations by the ACOG, whereas all other guidelines provide similar recommendations. The RANZCOG makes no special recommendations on the intrapartum period.

CONCLUSION

The differences among national guidelines point out the need for the adoption of an international consensus on the management of breech presentation.

Revisiting the management of term breech presentation: a proposal for overcoming some of the controversies

Background

The debate surrounding the management of term breech presentation has excessively focused on the mode of delivery. Indeed, a steady decline in the rate of vaginal breech delivery has been observed over the last three decades, and the soundness of the vaginal route was seriously challenged at the beginning of the 2000s. However, associations between adverse perinatal outcomes and antenatal risk factors have been observed in foetuses that remain in the breech presentation in late gestation, confirming older data and raising the question of the role of these antenatal risk factors in adverse perinatal outcomes. Thus, aspects beyond the mode of delivery must be considered regarding the awareness and adequate management of such situations in term breech pregnancies.

Main body

In the context of the most recent meta-analysis and with the publication of large-scale epidemiologic studies from medical birth registries in countries that have not abruptly altered their criteria for individual decision-making regarding the breech delivery mode, the currently available data provide essential clues to understanding the underlying maternal-foetal conditions beyond the delivery mode that play a role in perinatal outcomes, such as foetal growth restriction and gestational diabetes mellitus. In view of such data, an accurate evaluation of these underlying conditions is necessary in cases of persistent term breech presentation. Timely breech detection, estimated foetal weight/growth curves and foetal/maternal well-being should be considered along with these possible antenatal risk factors; a thorough analysis of foetal presentation and an evaluation of the possible benefit of external cephalic version and pelvic adequacy in each specific situation of persistent breech presentation should be performed.

Conclusion

The adequate management of term breech pregnancies requires screening and the efficient identification of breech presentation at 36 weeks of gestation, followed by thorough evaluations of foetal weight, growth and mobility, while obstetric history, antenatal gestational disorders and pelvis size/conformation are considered. The management plan, including external cephalic version and follow-up based on the maternal/foetal condition and potentially associated disorders, should be organized on a case-by-case basis by a skilled team after the woman is informed and helped to make a reasoned decision regarding delivery route.

[Breech Presentation: CNGOF Guidelines for Clinical Practice - Case Selection for Trial of Labour]

OBJECTIVE

The objective of this chapter is to examine on the basis of the knowledge currently available the criteria available before labour for selecting women who would be eligible for trial of vaginal delivery.

METHODOLOGY

Bibliographical research in French and English using the Medline and Cochrane databases between 1980 and 2019 and the recommendations of international societies.

RESULTS

It is recommended to offer women who wish to attempt a vaginal delivery at term a pelvimetry to decide with them on their mode of delivery (Grade C). The pelvimetric standards used at the time of the PREMODA study were anteroposterior diameter of inlet≥105mm, a transverse diameter of inlet≥120mm, a transverse interspinous diameter≥100mm. However, since there is no evidence about which pelvic measures to use, nor any evidence to set decision-making thresholds other than those set in published studies, the selected decision-making thresholds can be adjusted according to gestational age at delivery or fetal biometrics (Professional consensus). There is no argument for recommending the practice of pelvimetry in the case of delivery before 37 weeks gestational age (Professional consensus) and in the case of breech presentation discovered at the time of beginning of labour, the absence of pelvimetry alone does not contraindicate the attempt of vaginal delivery (Professional consensus). There is insufficient data to recommend the systematic use of fetal weight estimation and/or biparietal diameter measurement as acceptance criteria for a vaginal delivery attempt. In the event of a known fetal weight estimation before birth greater than 3800g, a cesarean section is to be preferred (Professional consensus). The breech presentation is not in itself a contraindication to an attempt of vaginal delivery for a small fetus for gestational age (Professional consensus). The presentation of the non-frank breech is not in itself a contraindication to an attempt of vaginal delivery (Professional consensus). In the case of premature breech delivery, current data do not allow to recommend one delivery route over another (Professional consensus). It is recommended to check the absence of hyperextension of the fetal head by ultrasound before an attempt of vaginal delivery (Professional consensus) and to prefer a cesarean section if such a position is found (Professional consensus). It is not recommended to propose a caesarean section with the sole reason of nulliparity (Grade C). The history of cesarean section is not in itself a contraindication to an attempt of vaginal delivery in the case of fetal breech presentation (Professional consensus). Premature rupture of the membranes is not in itself a contraindication to an attempt of vaginal delivery (Professional consensus).

CONCLUSION

A number of the factors analyzed in this chapter are to be incorporated into the decision-making process in order to choose with the woman whose fetus is in breech presentation the delivery route.

Adherence to guidelines and suboptimal practice in term breech delivery with perinatal death- a population-based case-control study in Norway

BACKGROUND

In a recent population-based study we reported excess risk of neonatal mortality associated with vaginal breech delivery. In this case-control study we examine whether deviations from Norwegian guidelines are more common in breech deliveries resulting in intrapartum or neonatal deaths than in breech deliveries where the offspring survives, and if these deaths are potentially avoidable.

MATERIAL AND METHODS

Case-control study completed as a perinatal audit including term breech deliveries of singleton without congenital anomalies in Norway from 1999 to 2015. Deliveries where the child died intrapartum or in the neonatal period were case deliveries. For each case, two control deliveries who survived were identified. All the included deliveries were reviewed by four obstetricians independently assessing if the deaths in the case group might have been avoided and if the management of the deviations from Norwegian guidelines were more common in case than in control deliveries.

RESULTS

Thirty-one case and 62 control deliveries were identified by the Medical Birth Registry of Norway. After exclusion of non-eligible deliveries, 22 case and 31 control deliveries were studied. Three case and two control deliveries were unplanned home deliveries, while all in-hospital deliveries were in line with national guidelines. Antenatal care and/or management of in-hospital deliveries was assessed as suboptimal in seven (37%) case and two (7%) control deliveries (p = 0.020). Three case deliveries were completed as planned caesarean delivery and 12 (75%) of the remaining 16 deaths were considered potentially avoidable had planned caesarean delivery been done. In seven of these 16 deliveries, death was associated with cord prolapse or difficult delivery of the head.

CONCLUSION

All in-hospital breech deliveries were in line with Norwegian guidelines. Seven of twelve potentially avoidable deaths were associated with birth complications related to breech presentation. However, suboptimal care was more common in case than control deliveries. Further improvement of intrapartum care may be obtained through continuous rigorous training and feedback from repeated perinatal audits.

MRI-based pelvimetric measurements as predictors for a successful vaginal breech delivery in the Frankfurt Breech at term cohort (FRABAT)

OBJECTIVES

The purpose of this study was to investigate the role of the maternal pelvis, assessed by MRI pelvimetry in nulliparous women expecting a term fetus in breech presentation, to predict a successful and safe vaginal birth.

STUDY DESIGN

In this monocentric and anonymized cohort study, we enrolled 367 nulliparous women with breech presentation at 39⁺⁰ to 41⁺⁰ weeks of gestation during a period of 8 years at the University Women's Hospital in Frankfurt/Main. Pelvic measurements were obtained by standard MRI imaging. We correlated the obstetric conjugate, the pubic angle and the distance between the ischial tuberosities (intertuberous distance) with the maternal and fetal outcomes of vaginally intended breech births. The data was evaluated using logistic regression analysis.

RESULTS

241 of 367 participants (65.7%) experienced a successful vaginal delivery whereas 126 patients (34.3%) were subjected to secondary cesarean section. An increasing obstetric conjugate was significantly associated with an increasing rate of successful vaginal deliveries. No significant correlation of the intertuberous distance and the pubic angle with the mode of delivery could be shown. Although statistically not significant, we were able to define cut-off values of 10.9 cm in the intertuberous distance and 70° in the pubic angle; below these values, no successful vaginal delivery was recorded. No significant differences in the short-term outcomes were seen between the neonates of the vaginal delivery and the cesarean section groups. Inter- and intraobserver variability showed excellent reproducibility for all MRI parameters.

CONCLUSION

The obstetric conjugate correlates with the rate of vaginal deliveries in nulliparous women at term and can be used as a useful criterion for pre-selection and counseling of women with breech presentation and the desire for a vaginal delivery.

New MRI Criteria for Successful Vaginal Breech Delivery in Primiparae

Background

Even if lower vaginal delivery success rates and impaired neonatal short-term outcomes have been reported for primiparous women with breech presentation, vaginal breech delivery remains an option for carefully selected patients. Because Magnetic resonance imaging (MRI) pelvimetry can provide additional information on maternal pelvic morphology, we sought to identify new MRI parameters that predict successful vaginal breech delivery.

Methods

In this retrospective unicentre study, 240 primiparous women with breech presentation at term underwent MRI pelvimetry. For all patients vaginal delivery was planned, according to German guidelines and if the conjugata vera (CV) was ≥12 cm. The patients with uneventful vaginal deliveries and the patients who underwent a secondary caesarean section were compared according to pelvimetric parameters and outcomes. Regression analyses were performed.

Results

In the vaginal delivery group (n = 162, (67.5%)), the distance between the spinae ischiadicae (interspinous diameter, ISD) was significantly enlarged. The ISD significantly influenced the mode of delivery in the regression analyses. The CV did not significantly differ between the groups. The patients with successful vaginal deliveries were significantly younger than the patients who underwent caesarean section. In the receiver operating characteristic (ROC) analysis, the area under the curve (AUC) for ISD was 67.7% (p<0.001, 95% CI [0.303–0.642]) and was higher considering the mother’s age (AUC = 73.1%, p<0.001, 95% CI [0.662–0.800]). The neonatal short-term outcomes were comparable in both groups.

Conclusion

The additional use of ISD may predict successful vaginal breech delivery and may be superior to the CV, which is more commonly used.

Trial Registration

DRKS00009957

Does pregnancy and/or shifting positions create more room in a woman's pelvis?

OBJECTIVE

The purpose of this study was to assess the impact of different positions on pelvic diameters by comparing pregnant and nonpregnant women who assumed a dorsal supine and kneeling squat position.

STUDY DESIGN

In this cohort study from a tertiary referral center in Germany, we enrolled 50 pregnant women and 50 nonpregnant women. Pelvic measurements were obtained with obstetric magnetic resonance imaging pelvimetry with the use of a 1.5-T scanner. We compared measurements of the depth (anteroposterior (AP) and width (transverse diameters) of the pelvis between the 2 positions.

RESULTS

The most striking finding was a significant 0.9-1.9 cm increase (7-15%) in the average transverse diameters in the kneeling squat position in both pregnant and nonpregnant groups. The average bispinous diameter in the pregnant group increased from 12.6 cm ± 0.65 cm in the supine dorsal to 14.5 cm ± 0.64 cm (P < .0001) in the kneeling squat; in the nonpregnant group the increase was from 12 cm ± 0.76 cm to 13.9 cm ± 1.04 cm (P < .0001). The average bituberous diameter in the pregnant group increased from 13.6 cm ± 0.93 cm in the supine dorsal to 14.5 cm ± 0.83 cm (P < .0001) in the kneeling squat position; in the nonpregnant women the increase was from 12.6 cm ± 0.92 cm to 13.5 cm ± 0.88 cm (P < .0001).

CONCLUSION

A kneeling squat position significantly increases the bony transverse and anteroposterior dimension in the mid pelvic plane and the pelvic outlet. Because this indicates that pelvic diameters change when women change positions, the potential for facilitation of delivery of the fetal head suggests further research that will compare maternal delivery positions is warranted.

Term breech deliveries in the Netherlands: did the increased cesarean rate affect neonatal outcome? A population-based cohort study

OBJECTIVE

The aim of this study was to evaluate the effect of the increased cesarean rate for term breech presentation on neonatal outcome. We also investigated whether the clinical case selection for vaginal delivery applied by Dutch obstetricians led to an optimization of neonatal outcome, or whether there is still room for improvement in terms of perinatal outcome.

DESIGN

Retrospective cohort.

SETTING

The Netherlands.

POPULATION

Singleton term breech deliveries from 37+0 to 41+6 weeks, excluding fetuses with congenital malformations or antenatal death.

METHOD

We used data from the Dutch national perinatal registry from 1999 up to 2007.

MAIN OUTCOME MEASURES

Perinatal mortality and morbidity.

RESULTS

We studied 58,320 women with a term breech delivery. There was an increase in the elective cesarean rate (from 24 to 60%). As a consequence, overall perinatal mortality decreased [1.3 0/00 vs. 0.7 0/00;odds ratio 0.51 (95% confidence interval 0.28–0.93)], whereas it remained stable in the planned vaginal birth group [1.7 0/00 vs. 1.6 0/00; odds ratio 0.96(95% confidence interval 0.52–1.76)]. The number of cesareans done to prevent one perinatal death was 338.

CONCLUSIONS

Adjustment of the national guidelines after publication of the Term Breech Trial resulted in a shift towards elective cesarean and a decrease of perinatal mortality and morbidity among women delivering a child in breech at term. Still, 40% of these women attempt vaginal birth. The relative safety of an elective cesarean should be weighed against the consequences of a scarred uterus in future pregnancies.

CONSORT 2010 explanation and elaboration: updated guidelines for reporting parallel group randomised trials

Overwhelming evidence shows the quality of reporting of randomised controlled trials (RCTs) is not optimal. Without transparent reporting, readers cannot judge the reliability and validity of trial findings nor extract information for systematic reviews. Recent methodological analyses indicate that inadequate reporting and design are associated with biased estimates of treatment effects. Such systematic error is seriously damaging to RCTs, which are considered the gold standard for evaluating interventions because of their ability to minimise or avoid bias. A group of scientists and editors developed the CONSORT (Consolidated Standards of Reporting Trials) statement to improve the quality of reporting of RCTs. It was first published in 1996 and updated in 2001. The statement consists of a checklist and flow diagram that authors can use for reporting an RCT. Many leading medical journals and major international editorial groups have endorsed the CONSORT statement. The statement facilitates critical appraisal and interpretation of RCTs. During the 2001 CONSORT revision, it became clear that explanation and elaboration of the principles underlying the CONSORT statement would help investigators and others to write or appraise trial reports. A CONSORT explanation and elaboration article was published in 2001 alongside the 2001 version of the CONSORT statement. After an expert meeting in January 2007, the CONSORT statement has been further revised and is published as the CONSORT 2010 Statement. This update improves the wording and clarity of the previous checklist and incorporates recommendations related to topics that have only recently received recognition, such as selective outcome reporting bias. This explanatory and elaboration document-intended to enhance the use, understanding, and dissemination of the CONSORT statement-has also been extensively revised. It presents the meaning and rationale for each new and updated checklist item providing examples of good reporting and, where possible, references to relevant empirical studies. Several examples of flow diagrams are included. The CONSORT 2010 Statement, this revised explanatory and elaboration document, and the associated website (www.consort-statement.org) should be helpful resources to improve reporting of randomised trials.

Has pelvimetry a role in current obstetric practice?

Radiological pelvimetry is still requested in some centres before planned vaginal delivery for breech presentation or following a previous caesarean section. In a retrospective review of the utilisation of pelvimetry in 167 cases in our department, 103 (62%) and 64 (38%) had pelvimetry in the postnatal and antenatal periods respectively. Antero-posterior inlet and outlet diameters were inadequate in 19.2% and 16.2% respectively. Of those who had postnatal pelvimetry, only 36 (35%) returned to our unit for further confinement and the caesarean section rate in this group was 75%. The main indications for antenatal pelvimetry were breech presentation (28), previous caesarean section (23) and anticipated cephalopelvic disproportion (13). The caesarean section rates in these groups were 82%, 70% and 45% respectively. However, the emergency caesarean section rate in the breech presentation group was 28%. Nine patients (32%) of those who had breech presentation and delivered by elective caesarean section had normal pelvic measurements. Pelvimetry should only be performed if its results will influence the mode of delivery. Pelvimetry may be useful in selecting fetuses with breech presentation for vaginal delivery or elective caesarean section. However it would increase the likelihood of caesarean section in cephalic presentation.

Racial differences in pelvic anatomy by magnetic resonance imaging

OBJECTIVES

To use static and dynamic magnetic resonance imaging (MRI) to compare dimensions of the bony pelvis and soft tissue structures in a sample of African-American and white women.

METHODS

This study used data from 234 participants in the Childbirth and Pelvic Symptoms Imaging Study, a cohort study of 104 primiparous women with an obstetric anal sphincter tear, 94 who delivered vaginally without a recognized anal sphincter tear and 36 who underwent by cesarean delivery without labor. Race was self-reported. At 6-12 months postpartum, rapid acquisition T2-weighted pelvic MRIs were obtained. Bony and soft tissue dimensions were measured and compared between white and African-American participants using analysis of variance, while controlling for delivery type and age.

RESULTS

The pelvic inlet was wider among 178 white women than 56 African-American women (10.7+/-0.7 cm compared with 10.0.+0.7 cm, P<.001). The outlet was also wider (mean intertuberous diameter 12.3+/-1.0 cm compared with 11.8+/-0.9 cm, P<.001). There were no significant differences between racial groups in interspinous diameter, angle of the subpubic arch, anteroposterior conjugate, levator thickness, or levator hiatus. In addition, among women who delivered vaginally without a sphincter tear, African-American women had more pelvic floor mobility than white women. This difference was not observed among women who had sustained an obstetric sphincter tear.

CONCLUSION

White women have a wider pelvic inlet, wider outlet, and shallower anteroposterior outlet than African-American women. In addition, after vaginal delivery, white women demonstrate less pelvic floor mobility. These differences may contribute to observed racial differences in obstetric outcomes and to the development of pelvic floor disorders.

Caesarean section in a semi-rural hospital in Northern Namibia

Background

Increasing caesarean sections rates (CSR) are a major public health concern and the prevention of the first caesarean section, which often leads to repeat operations, is an important issue. Analyzing caesarean sections can help to identify factors associated with variations in CSR and help to assess the quality of clinical care.

Methods

In a retrospective observational study, during a two year period, indications of 576 caesarean sections were analyzed using intra-operative internal pelvimetry and a record keeping system in a semi-rural hospital in Northern Namibia.

Results

Most caesarean sections were done for dystocia (34%) followed by repeat caesarean section (31%). The true conjugate (distance between the promontorium to mid pubic bone) was significantly smaller in these recurrent indication groups when compared to non recurrent indications.

Conclusion

In this rural hospital the introduction of Delee Pelvimetry and a caesarean section record keeping system was found to be a simple and cheap method to analyse indications for caesarean sections, which may help in reducing unnecessary caesarean sections.

Quelle place pour la radiopelvimétrie au XXIe siècle?

The purpose of this article was to perform a critical analysis of publications having estimated the utility of X-ray pelvimetry, in order to allow tangible and useful conclusions for the clinical practice. X-ray pelvimetry was proposed in 3 indications: trial of labour among patients with a history of caesarean section, breech presentation, suspicion of cephalopelvic disproportion. The large majority of these publications are retrospective studies, studying a low number of patients and especially without control groups or randomisation. Their contradictory results and their methodological weaknesses do not allow any conclusion. Published randomised trials are exceptional. Among patients with a history of caesarean section, there is only one randomised trial; it demonstrates that ante-partum X-ray pelvimetry is not necessary prior to a trial labour in women with one previous caesarean section. It increases the caesarean section rate and is a poor predictor of the outcome of labour. There is also only one randomised trial which evaluated the interest of X-ray pelvimetry in patients with a breech presentation: the use of pelvimetry in breech presentation at term does not significantly reduce the overall caesarean-section rate, and does not improve the neonatal issues. However, it allows better selection of the delivery route, with a significantly lower emergency Caesarean-section rate. Finally, the only one randomised trial having studied the utility of X-ray pelvimetry for the prediction of cephalopelvic disproportion shows that pelvimetry is a poor predictor of the outcome of labour, has no influence on the neonatal issues and increases the caesarean sections rate. Furthermore, although radiation exposure during a X-ray pelvimetry is very weak, diagnostic X-ray studies during any stage of gestation have been shown to increase the risk of childhood cancer in the irradiated fetus. In the rare cases where pelvimetry is useful (trial of labour with a breech presentation), it is thus careful to perform a MRI pelvimetry.

Synchronous colectomy and caesarean section for fulminant ulcerative colitis: case report and review of the literature

Ulcerative colitis (UC) affects women of all ages, with a peak incidence in the third and fourth decades, at the prime of their reproductive years [Baiocco PJ, Korelitz BI (1984) The influence of inflammatory bowel disease and its treatment on pregnancy and fetal outcome. J Clin Gastroenterol 6(3):211-216]. We describe a case of fulminating UC at 28 weeks' gestation treated by combined emergency subtotal colectomy and caesarean section with excellent foetal and maternal outcome. A treatment algorithm is suggested, and the literature surrounding inflammatory bowel disease in pregnancy is reviewed.

Magnetic resonance-based serial pelvimetry: do maternal pelvic dimensions change during pregnancy?

OBJECTIVE

The purpose of the study was to evaluate the stability of the maternal pelvis over the course of the third trimester and the puerperium.

STUDY DESIGN

Pregnant patients were recruited to undergo comparative magnetic resonance-based pelvimetry and fetal ultrasonography at 37 to 38 weeks of gestation. Most of the patients were recruited from a study of women who planned a trial of labor after a previous cesarean delivery for cephalopelvic disproportion. These results have been reported previously. Patients then underwent magnetic resonance-based pelvimetry within 3 days and at 3 months after delivery. Postdelivery analysis was used to answer the question: Do pelvic dimensions change after delivery?

RESULTS

Eighteen patients completed the study. Eleven of the patients underwent cesarean deliveries, of which 4 deliveries were before labor. Seven patients had successful vaginal births after their previous cesarean delivery. Statistical analysis of the 18 patients determined that pelvic measurements did not demonstrate change over the course the study.

CONCLUSION

Serial magnetic resonance-based pelvimetry showed relative stability of pelvic measurements through the course of pregnancy and delivery. If comparative pelvimetry is to be useful as an antepartum predictor of labor success, then it may be possible to obtain reliable pelvimetry in those patients anytime after delivery.

The term breech presentation: Neonatal results and obstetric practices in France

OBJECTIVE

Compare neonatal complications according to the planned mode of delivery and according to whether the women gave birth at a maternity unit that applied "consensus" guidelines.

STUDY DESIGN

The study used the database of the AUDIPOG Sentinel Network (n=71,919 pregnancies between 1994 and 2000). The principal outcome was a composite variable that included neonatal morbidity and mortality. A survey of obstetric practices was sent to 175 maternity units belonging to the network. Consensus guidelines were defined from the survey responses and taken into account in the database analysis.

RESULTS

Neonatal complications did not differ between the group of women with term babies in breech presentation for whom vaginal delivery was planned and those for whom an elective caesarean was planned (adjusted OR=1.33; 95% CI: 0.63-2.80). The survey allowed us to define a set of six criteria for deciding on mode of delivery; it established a consensus, followed by 42% of the maternity units in the study. The rate of neonatal complications among the women with planned vaginal delivery was lower for those giving birth in units that applied the consensus guidelines than among those in the other units: adjusted OR=0.27 (95% CI: 0.09-0.85).

CONCLUSION

The risk of neonatal morbidity according to planned mode of delivery for term breech babies was lower for those giving birth in units that applied the consensus guidelines than among those in the other units.

Obstetric MRI

Ultrasound is the imaging modality of choice for pregnant patients. However, MRI is increasingly utilized in patients in whom the sonographic diagnosis is unclear. These include maternal conditions unique to pregnancy such as ectopic pregnancy, placenta accreta, and uterine dehiscence. MRI is also being increasingly utilized in the assessment of abdominopelvic pain in pregnancy, in particular in assessment for appendicitis. Fetal MRI is performed to assess central nervous system (CNS) abnormalities and patients who are considering fetal surgery for conditions such as neural tube defects, congenital diaphragmatic hernia, and masses that obstruct the airway. In the future, functional MRI and fetal volumetry may provide additional information that can aid in our care of complicated pregnancies.

Normal Labor: Mechanism and Duration

Labor is refers to the chain of physiologic events that allows a fetus to undertake its journey from the uterus to the outside world. The mean duration of a singleton preganancy is 40.0 weeks (280 days), which is dated from the first day of the last normal menstrual period. The period from 37.0 weeks (259 days) to 42.0 weeks (294 days) of gestation is regarded as "term". This article focuses on the onset progress, and mechanics of normal labor term. Topics such as preterm labor (labor before 37 weeks), postterm labor (labor after 42 weeks), and abnormal labor and delivery have not been addressed and are discussed in detail elsewhere in this issue.

A review of the current use of magnetic resonance imaging in pregnancy and safety implications for the fetus

This paper presents an overview of the application of and risks of exposure to Magnetic Resonance Imaging (MRI) in pregnancy. It reviews the risks to the fetus by considering the hazards in terms of the three main components of an MRI system. These are the static magnetic field, the time-varying magnetic gradient fields and the pulsed radio frequency fields. The hazards discussed are biological effects, miscarriage, heating effects and acoustic noise exposure. This paper also presents a survey of MRI sites within the United Kingdom to ascertain the extent of MRI usage in pregnancy. To validate the situation of MRI in pregnancy a survey was sent to 352 MR units throughout the United Kingdom. The questions were grouped to assess (a) maternal MRI diagnosis (b) fetal MRI and (c) work practices for pregnant MRI staff. The results showed that 91% of sites were imaging pregnant women in need of diagnosis in the second and third trimester. This paper highlights that MRI can add information for fetal central nervous system abnormalities identified by ultrasound screening, however within the UK direct fetal imaging was only performed in 8% of sites. This paper indicates the need for research to be undertaken for specific MRI clinical conditions. It also advises that risk assessment for pregnant staff working in MRI is performed, and that there is a clear need for further research into the effects of MRI in pregnancy as there is a need for clear authoritive advice.

The magnetic resonance imaging-based fetal-pelvic index: a pilot study in the community hospital

OBJECTIVE

This study was undertaken to assess feasibility of magnetic resonance imaging (MRI) pelvimetry in conjunction with fetal ultrasonography as a technique in evaluating patients with previous cesarean sections for cephalopelvic disproportion (CPD).

STUDY DESIGN

Pregnant patients with one previous cesarean section for CPD who planned a trial of labor after cesarean (TOLAC) were recruited to undergo MRI pelvimetry and fetal ultrasonography at 37 to 38 weeks. Entry criteria included no previous successful vaginal deliveries and no contraindications for vaginal delivery in the ongoing pregnancy. A fetal-pelvic index was calculated for each patient but not disclosed to patients or their physicians. The pregnancies were managed routinely. Analysis after delivery was used to ascertain whether this index would have predicted clinical outcome.

RESULTS

There were no difficulties in performing the MRI or ultrasound. Sixteen patients completed their pregnancies. Three patients did not labor. The fetal-pelvic index was plotted on a scattergram and compared with the outcome. Three discriminatory zones were identified. Five of 6 patients in the most favorable zone delivered successfully. Two patients in the most unfavorable zone had failed vaginal birth after cesarean section (VBAC) attempts. In the 5 patients in the middle intermediate zone, TOLAC success appeared to depend on fetal presentation and gestational age.

CONCLUSION

The use of comparative MRI pelvimetry and fetal ultrasonography is feasible in a community hospital. In this pilot study, it appeared to have potential in enhancing the management of VBAC candidates. This technique may allow sorting of patients before labor into zones that would favor or preclude VBAC attempts.

Imaging modalities in obstetrics and gynecology

The practicing emergency physician often encounters diagnostic dilemmas involving the choice of the most appropriate radiologic study to evaluate patients in the emergency department. In addition, the uncertainty of potentially harmful fetal effects of radiation in the pregnant patient may add unnecessary delay and concern in the workup of obstetric emergencies. An emergency physician's in-depth understanding of the strengths, limitations, and potentially harmful effects of radiologic studies allows the safest and most appropriate studies to be ordered for the gynecologic and obstetric population. With the explosion of interest and growing level of expertise in focused emergency department ultrasonography during the last decade, the practicing emergency physician should add this skill to his or her armamentarium in the future. Many emergency physicians are already comfortable in using radiologic technologies in their daily practice and have discovered how quickly vital and specific information can be obtained.

Obstetric MR pelvimetry: reference values and evaluation of inter- and intraobserver error and intraindividual variability

PURPOSE

To establish obstetric magnetic resonance (MR) pelvimetric reference values in a large study population and stratify them according to delivery modality and to determine the intra- and interobserver error and intraindividual variability of MR pelvimetric assessment in volunteers.

MATERIALS AND METHODS

MR pelvimetric data were retrospectively reviewed in 781 women (mean age, 28.9 years +/- 5.2 [SD]) clinically referred, and the data were correlated to obstetric history to derive normative values. Five observers assessed results of multiple MR pelvimetric examinations in 10 female volunteers (mean age, 34.7 years +/- 6.0; eight nullipara, two primipara) to provide data for measurement error analysis.

RESULTS

All values were higher in the spontaneous vaginal delivery subgroup (n = 100) and lower in the cesarean section or vacuum extraction subgroup (n = 130; intersubgroup difference, P <.001, Mann-Whitney U test). Pelvimetric parameters in the group undergoing spontaneous vaginal delivery were as follows: obstetric conjugate, 121.7 mm +/- 8.6; interspinous distance, 112.3 mm +/- 7.9; intertuberous distance, 120.6 mm +/- 11.3; transverse diameter, 129.5 mm +/- 8.7; and sagittal outlet, 115.8 mm +/- 9.9. In the volunteer study, intraobserver, interobserver, and intraindividual reliabilities were high for the obstetric conjugate (0.94-0.96), interspinous distance (0.92-0.95), and transverse diameter (0.95-0.98) but low for intertuberous distance (0.64-0.87) and sagittal outlet (0.66-0.85).

CONCLUSION

Pelvimetric dimensions are smaller in women undergoing cesarean section or vacuum extraction than they are in those delivering vaginally. The pelvimetric parameters associated with the largest measurement errors are intertuberous distance and sagittal outlet.

Breech vaginal delivery at or near term

Three percent to 4% of term fetuses will be breech at delivery. Evidence from randomized controlled trials has found a policy of planned cesarean section to be significantly better for the singleton fetus in breech presentation at term compared to a policy of planned vaginal birth. However, some women may wish to avoid cesarean section and for others, cesarean section may not be possible. We undertook this review to identify factors associated with higher and lower risk of adverse fetal or neonatal outcome at term during vaginal breech delivery. We searched MEDLINE from 1966 to 2002 using the search terms vaginal breech delivery and breech presentation and retrieved all relevant articles. We also reviewed personal references and reference lists of articles retrieved. Women who are older or who have a fetus that is either in footling presentation, has a hyperextended head or is estimated to weigh <2500 g or >4000 g may be at higher risk of adverse fetal outcome. Prolonged labor or not having an experienced clinician at vaginal breech birth may also increase the risk. Women with a fetus in breech presentation at term should be offered the option of delivery by planned cesarean section and should be informed that this will reduce their risk of adverse fetal or neonatal outcome. Practitioners should develop and maintain skills at vaginal breech delivery for those women not wishing or not able to be delivered by cesarean section.

MR obstetric pelvimetry: effect of birthing position on pelvic bony dimensions

OBJECTIVE

The aim of our study was to measure the impact of supine and upright birthing positions on MR pelvimetric dimensions.

MATERIALS AND METHODS

MR pelvimetry was performed in 35 nonpregnant female volunteers in an open 0.5-T MR imaging system with patients in the supine, hand-to-knee, and squatting positions. The obstetric conjugate; sagittal outlet; and interspinous, intertuberous, and transverse diameters were compared among positions.

RESULTS

With patients in the hand-to-knee and squatting positions, the sagittal outlet (11.8 +/- 1.3 cm and 11.7 +/- 1.3 cm) exceeded that in the supine position (11.5 +/- 1.3 cm; p = 0.002 and p = 0.01, respectively), as did the interspinous diameter (11.6 +/- 1.1 cm and 11.7 +/- 1.0 cm vs 11.0 +/- 0.7 cm; p < 0.0001, in both cases). Intertuberous diameter was wider with patients in the squatting position than in the supine position (12.7 +/- 0.8 cm vs 12.4 +/- 1.1 cm; p = 0.01). Only the obstetric conjugate was smaller with patients in the upright squatting position than in the supine position (12.3 +/- 0.8 cm vs 12.4 +/- 0.9 cm; p = 0.01). Transverse diameter did not change significantly in any position.

CONCLUSION

An upright birthing position significantly expands female pelvic bony dimensions, suggesting facilitation of labor and delivery.

Study design for concurrent development, assessment, and implementation of new diagnostic imaging technology

With current constraints on health care resources and emphasis on value for money, new diagnostic imaging technologies must be assessed and their value demonstrated. The state of the art in the field of diagnostic imaging technology assessment advocates a hierarchical step-by-step approach. Although rigorous, such a hierarchical assessment is time-consuming, and, given the current rapid advances in technology, results are often too late to influence management and policy decisions. The purpose of this article is to discuss a study design in which development, assessment, and implementation of new diagnostic imaging technology take place concurrently in one integrated process. An empirically based pragmatic study design is proposed for imaging technology assessment. To minimize bias and enable comparison with current technology, a randomized controlled design is used whenever feasible and ethical. Outcome measures should reflect the clinical decision-making process based on imaging information and acceptance of the new test. Outcome measures can include additional imaging studies requested, costs of diagnostic work-up and treatment, physicians' confidence in therapeutic decision making, recruitment rate, and patient outcome measures related to the clinical problem. The key feature of the proposed study design is analysis of trends in outcome measures over time.