[Fetal scalp blood sampling for pH and lactate measurement during labour]

[Is it possible to safely reduce the use of in utero pH in the delivery room? Analysis of practices]

OBJECTIVE

To evaluate our clinical practices since the implementation of different tools to reduce the use of pH in utero (pHiu) in the delivery room.

METHODS

A single-centre retrospective study was conducted in our university maternity hospital of Lille from October 2016 to March 2021. All patients in labour with a vaginal delivery agreement, a fetus in cephalic presentation and no contraindication to perform a pHiu were included. Since 2019, team training in fetal heart rate interpretation and a change in birth room practices with the introduction of fetal scalp pacing have been implemented to reduce the use of pH in utero. In order to evaluate the impact on clinical practices, the rate of pHiu, the number of pHiu performed per patient, the rates of instrumental deliveries, caesarean sections and pH at birth below 7.0 were studied and compared over time.

RESULTS

In total, 1515 patients had one or more pHiu during our study period, i.e. 7.3% (1515/20,562). The rate of pHiu decreased significantly from 2016 to 2021: in 2016, 12.1% (142/1171) of our sample had a pHiu during their labour, compared to 3.4% (33/963) in 2021. pH < 7.0 remained stable, ranging from 1.6 to 2.2%. Similarly, the rates of instrumental deliveries and caesarean sections remained stable, ranging from 17.7% to 21% and from 9.8% to 11.6%, respectively.

CONCLUSION

Improved knowledge of fetal physiology, awareness of teams of the limits of pHiu and introduction of fetal scalp stimulation have led to a decrease in the number of pHiu, without an increase in the rates of neonatal acidosis, instrumental deliveries and caesarean sections.

Cryopreserved embryo replacement is associated with higher birthweight compared with fresh embryo: multicentric sibling embryo cohort study

Birth weight (BW) is higher after frozen embryo transfer (FET) than after fresh embryo replacement. No study has compared the BW of siblings conceived using the same oocyte/embryo cohort. The aim of this study was to determine whether the freezing-thawing procedure is involved in such difference. Multicenter study at Montpellier University Hospital, Clinique Ovo, Canada and Grenoble-Alpes University Hospital. The first cohort (Fresh/FET) included in vitro fertilization (IVF) cycles where the older was born after fresh embryo transfer (n = 158) and the younger after transfer of frozen supernumerary embryos (n = 158). The second cohort (FET/FET) included IVF cycles where older and younger were born after FET of embryos from the same cohort. The mean adjusted BW of the FET group was higher than that of the fresh group (3508.9 ± 452.4 g vs 3237.7 ± 463.3 g; p < 0.01). In the FET/FET cohort, the mean adjusted BW was higher for the younger by 93.1 g but this difference is not significant (3430.2 ± 347.6 g vs 3337.1 ± 391.9 g; p = 0.3789). Our results strongly suggest that cryopreservation is directly involved in the BW variation. Comparing BW difference between Fresh/FET cohort and FET/FET one, it suggests that parity is not the only responsible, increasing the role of cryopreservation step in BW variation.

Three-dimensional magnetic resonance imaging of fetal head molding and brain shape changes during the second stage of labor

To demonstrate and describe fetal head molding and brain shape changes during delivery, we used three-dimensional (3D) magnetic resonance imaging (MRI) and 3D finite element mesh reconstructions to compare the fetal head between prelabor and the second stage of labor. A total of 27 pregnant women were examined with 3D MRI sequences before going into labor using a 1 Tesla open field MRI. Seven of these patients subsequently had another set of 3D MRI sequences during the second stage of labor. Volumes of 2D images were transformed into finite element 3D reconstructions. Polygonal meshes for each part of the fetal body were used to study fetal head molding and brain shape changes. Varying degrees of fetal head molding were present in the infants of all seven patients studied during the second phase of labor compared with the images acquired before birth. The cranial deformation, however, was no longer observed after birth in five out of the seven newborns, whose post-natal cranial parameters were identical to those measured before delivery. The changing shape of the fetal brain following the molding process and constraints on the brain tissue were observed in all the fetuses. Of the three fetuses presenting the greatest molding of the skull bones and brain shape deformation, two were delivered by cesarean-section (one after a forceps failure and one for engagement default), while the fetus presenting with the greatest skull molding and brain shape deformation was born physiologically. This study demonstrates the value of 3D MRI study with 3D finite element mesh reconstruction during the second stage of labor to reveal how the fetal brain is impacted by the molding of the cranial bones. Fetal head molding was systematically observed when the fetal head was engaged between the superior pelvic strait and the middle brim.

Method validation of a set of 12 GEM® Premier™ 4000 blood gas analyzers for point-of-care testing in a university teaching hospital

Background

Blood gas analyzers are o0.ften integrated into point-of-care testing provisions. International standards (ISO 22870 and 15189) as adapted to French COFRAC regulations make accreditation of point-ofta-care testintag obligatory. We installed and assessed 12 GEM PREMIER 4000 analyzers for pH, pCO₂, pO₂, Na⁺, K⁺, Cl^-, Ca²⁺, lactate, hemoglobin and oxyhemoglobin (O₂Hb) at Clermont-Ferrand Hospital. These instruments were distributed across 11 care sites in the hospital.

Methods

Precision was studied at two control levels for each parameter. Comparisons between GEM analyzers were performed (on 30 samples) for pH, pCO₂, pO₂, Na⁺, K⁺, Cl^-, Ca²⁺, lactate, hemoglobin and O₂Hb; and between GEM analyzers and the central laboratory for Na⁺, K⁺, Cl^-, Ca²⁺ and hemoglobin (on 30–50 samples). Uncertainty in measurement (UM) was evaluated with an approach using reproducibility and accuracy data.

Results

The coefficients of variation (CVs) were in line with recommendations, except for the repeatability CV for pO₂. All CVs were below 4%. All comparisons complied with recommendations. Uncertainties of measurement were also validated.

Conclusion

Our results met standard requirements and the 12 analyzers were assessed as suitable for point-of-care testing in services of academic medical centers, as exemplified at Clermont-Ferrand hospital.

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Complete method validation of 12 analyzers for POCT in a multisite hospital.

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First published values of uncertainty in measurement very useful for pO2 and O₂Hb.

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Comparison between GEM4000 and central lab analyzers for Na⁺, Cl^-, K⁺, lactate, Hb.

[Fetal scalp pH during labor: Which threshold for intervention?]

OBJECTIVE

In case of abnormal fetal heart rate, there is no consensus on the decision threshold pH scalp leading to a rapid birth. The objective of this study was to compare neonatal issues and cesarean rate in two maternity using different decision thresholds of scalp pH.

MATERIAL AND METHODS

A comparative retrospective study conducted in two level III maternity units between January 2013 and May 2014, one maternity unit used a decision threshold of 7.20 (maternity unit 7,20), and the other one a threshold of 7.25 (maternity unit 7,25). An adverse neonatal outcome was defined by a composite endpoint of neonatal morbidity. The risk of cesarean was assessed using a multivariate analysis.

RESULTS

One hundred and four patients were included in the maternity unit 7,20 and 163 patients in the maternity 7,25. Adverse neonatal outcome was similar in both maternities (25% vs. 30,1%; P=0.4). The average pH at birth was similar in both maternities, as well as the Apgar score at 5minutes and neonatal transfer rates. However, BE<-12 was more frequent in maternity using 7,20 scalp pH threshold (7% vs. 0%; P<0.01). The cesarean rate was higher in maternity 7,25 (adjusted OR=2.23 95% CI [1.17-4.25]).

CONCLUSION

It seems that a decisional threshold fixed to 7,20 could be used reasonably. It could allow to reduce cesarean rate. Other studies are, however, needed to confirm that such threshold of 7,20 does not increase the risk of severe acidosis.

[Per partum acidosis: Interest and feasibility of cerebral Doppler during labor]

OBJECTIVES

To evaluate feasibility and interest of fetal cerebral Doppler during labor and the link with fetal pH to predict perinatal fetal asphyxia.

METHODS

Our prospective study in a university perinatal center, included patients during labor. There were no risk factors during pregnancy and patients were included after 37 weeks of pregnancy. For each patient an ultrasound with cerebral Doppler was done concomitant to a fetal scalp blood sample. We collected maternal and fetal characteristics as well as cervix dilatation, fetal heart rate analysis and fetal presentation.

RESULTS

Among 49 patients included over a period of 4 months, cerebral Doppler failed in 7 cases (11%). Majority of failure occurred at 10cm of dilatation (P=0.007, OR=14.1 [1.483; 709.1275]). Others factors like: maternal age, body mass index, parity, history of C-Section were not associated with higher rate of failure. We did not found either significant correlation between cerebral fetal Doppler and pH on fetal scalp blood sample (r=0.15) nor pH at cord blood sample (r=0.13). No threshold of cerebral Doppler is significant for fetal asphyxia prediction.

CONCLUSION

Fetal cerebral Doppler is feasible during labor with a low rate of failure but not a good exam to predict fetal acidosis and asphyxia.

Cardiotocographic findings in the second stage of labor among fetuses delivered with acidemia: a comparison of two classification systems

BACKGROUND

The RCOG classification system of CTG trace is widely used for the analysis of the fetal heart rate during the first and second stage of labor. Other authors proposed specific classification systems for the second stage traces.

OBJECTIVE

To evaluate the accuracy of RCOG and Piquard cardiotocographic patterns classification systems in predicting fetal acidemia in the second stage of labor.

STUDY DESIGN

This was a nested retrospective case-control study including fetuses delivered with metabolic acidemia in the second stage of labor and a matched group of non-acidemic fetuses as controls. Cases and controls were selected from the electronic medical records of the University Hospital of Bologna between 2008 and 2013. The last 60min of the cardiotocograms recorded during the second stage of labor were independently classified by a senior consultant and a trainee according to RCOG and Piquard classifications. The inter-observer agreement and the accuracy of the two classifications in predicting fetal acidemia were evaluated.

RESULTS

In all, 82 acidemic fetuses and 164 controls were recruited in the study period. Regarding the CTG traces assessment, the inter-observer agreement was moderate for both the categorizations (RCOG κ=0.584). Unclassifiable CTG patterns were more frequent among acidemic fetuses vs controls either at RCOG and at Piquard evaluation (26.8% vs 7.9%, p<0.001). Both systems yielded a moderate and comparable ability to predict fetal acidemia (RCOG ROC AUC=0.731; 95% CI 0.660-0.795; Piquard ROC AUC=0.773; 95% CI 0.704-0.833. DeLong z-test=1.186, p=0.236).

CONCLUSIONS

RCOG and Piquard systems have a moderate accuracy in identifying acidemic fetuses during the second stage of labor. The occurrence of unclassifiable findings seems significantly more common among the acidemic fetuses.

[Value of fetal scalp pH sampling early during the first stage of labour]

OBJECTIVE

When fetal heart rate (FHR) abnormalities occur early during the first stage of labour, the risk of caesarean increases. In this study, we assessed the value of fetal scalp pH sampling on delivery mode, among women with FHR abnormalities before or at 5 cm cervical dilatation.

METHODS

It is a retrospective observational study setting in a tertiary maternity center. All women with a live singleton cephalic fetus at term, who had a fetal scalp pH sampling, between January and July 2009, were included. We compared vaginal delivery and neonatal morbidity rates according to cervical dilatation at the time of the first fetal scalp pH sampling (≤ 5 or >5 cm). Neonatal morbidity was defined by pH at birth less or equal to 7.10 and/or 5 minutes Apgar score less or equal to 7 and/or neonatal transfer.

RESULTS

During the study period, 108 women had at least one fetal scalp pH sampling, 8.5% of eligible women. Forty-six (42.6%) had a first pH at or before 5 cm cervical dilatation. The vaginal delivery rate was 62% and increased with increasing cervical dilatation at the time of the first fetal scalp pH (P<0.001). Among women who had fetal scalp pH early during the first stage of labour (≤ 5 cm), 50% delivered vaginally versus 71% when the fetal scalp pH was performed after 5 cm (P=0.026). The frequency of pH at birth less or equal to 7.10 was lower when the fetal scalp pH was performed before or at 5 cm (4.4% versus 16.9%, P=0.04). Neonatal morbidity rates were similar in both groups.

CONCLUSION

In this study, when FHR abnormalities occur early during the first stage of labour, use of fetal scalp pH sampling allows a vaginal delivery in half of cases without an increase in neonatal morbidity.