Accuracy of intrapartum fetal blood gas analysis by scalp sampling: A retrospective cohort study.

Fetal blood gas analysis (FBGA) using scalp blood is commonly used to identify serious fetal distress. However, there is a lack of data regarding its accuracy and reliability. The aim of this study was to determine the positive predictive value (PPV) and negative predictive value (NPV) of FBGA for predicting postpartum acidosis in case of nonreassuring fetal heart rate tracings (NRFHRT). To this end, we conducted a retrospective cohort study of singleton term deliveries with NRFHRT according to Fédération Internationale de Gynécologie et d'Obstétrique and Fisher cardiotocography scores undergoing FBGA in a university hospital. The PPV and NPV of FBGA regarding neonatal acidosis (defined as a pH value ≤ 7.15 in arterial or venous umbilical cord blood) and Apgar scores indicating neonatal depression (defined as a 5-min Apgar score ≤5) were evaluated. Multivariate analysis was used to determine the influence of cardiotocography variations and the time delay between FBGA and delivery on the accuracy of FBGA. We analyzed 343 deliveries with NRFHRT. In 32 (9%) of these cases, fetal acidosis was confirmed by a postpartum umbilical cord blood pH value ≤ 7.15. In 308/343 (90%) cases, FBGA identified NRFHRT as false positive (as confirmed by nonacidotic postpartum pH values) and thus avoided unnecessary interventions such as operative delivery. The overall test accuracy of FBGA was 91%. FBGA accurately predicted postpartum cord blood pH values with a margin of ±0.2 in 319/343 (93%) cases. On the other hand, the false negative rate of FBGA was 8% (29/343). The PPV and NPV of FBGA for predicting postpartum acidosis were 50% and 91%, respectively. The sensitivity was 9% and the specificity was 99%. In a multivariate logistic regression analysis, maternal body mass index (odds ratio [OR] 1.1; 95% confidence interval [CI] 1.01-1.17; P = .029) and cardiotocography variations (OR 0.80; 95% CI 0.66-0.98; P = .029) independently affected the predictive value of FBGA. The PPV of FBGA regarding neonatal depression according to Apgar scores was low with only 17%. We conclude that FBGA may be used in clinical practice to rule out, but not to rule in, neonatal acidosis in parturients with NRFHRT. It can avoid unnecessary interventions such as cesarean section or operative vaginal delivery in up to 90% of cases, but cannot reliably detect fetal acidosis.

[Per partum acidosis: Interest and feasibility of cerebral Doppler during labor]. / Intérêt et faisabilité du Doppler cérébral en cours de travail pour prédire une acidose néonatale.

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.

Cervical dilatation and grade of doctor affects the interval between decision and result of fetal scalp blood sampling in labour.

Fetal scalp blood sampling (FSBS) is used to provide information regarding fetal acid-base status during labour. This study assessed the interval between the decision to perform the procedure and obtaining the result and evaluated whether it is affected by cervical dilatation or the experience of the doctor. The median time for FSBS was 10 min. When cervical dilatation was ≤4 cm samples took approximately 30% longer to obtain. After adjustment for dilation, there were no significant differences between different grades of doctors. FSBS is shorter than previously reported; clinicians should be aware that procedures in early labour take longer to complete.

Neonatal complications associated with use of fetal scalp electrode: a retrospective study.

OBJECTIVES: To estimate the incidence and risk of complications associated with a fetal scalp electrode and to determine whether its application in the setting of operative vaginal delivery was associated with increased neonatal morbidity. DESIGN: Retrospective cohort study. SETTING: Twelve clinical centers with 19 hospitals across nine American Congress of Obstetricians and Gynecologists US districts. POPULATION: Women in the USA. METHODS: We evaluated 171 698 women with singleton deliveries ≥ 23 weeks of gestation in a secondary analysis of the Consortium on Safe Labor study between 2002 and 2008, after excluding conditions that precluded fetal scalp electrode application such as prelabour caesarean delivery. Secondary analysis limited to operative vaginal deliveries ≥ 34 weeks of gestation was also performed. MAIN OUTCOME MEASURES: Incidences and adjusted odds ratios with 95% confidence intervals of neonatal complications were calculated, controlling for maternal characteristics, delivery mode and pregnancy complications. RESULTS: Fetal scalp electrode was used in 37 492 (22%) of deliveries. In non-operative vaginal delivery, fetal scalp electrode was associated with increased risk of injury to scalp due to birth trauma (1.2% versus 0.9%; adjusted odds ratios 1.62; 95% confidence intervals 1.41-1.86) and cephalohaematoma (1.0% versus 0.9%; adjusted odds ratios 1.57; 95% confidence intervals 1.36-1.83). Neonatal complications were not significantly different comparing fetal scalp electrode with vacuum-assisted vaginal delivery and vacuum-assisted vaginal delivery alone or comparing fetal scalp electrode with forceps-assisted vaginal delivery and forceps-assisted vaginal delivery alone. CONCLUSIONS: We found increased neonatal morbidity with fetal scalp electrode though the absolute risk was very low. It is possible that these findings reflect an underlying indication for its use. Our findings support the use of fetal scalp electrodes when clinically indicated. TWEETABLE ABSTRACT: Neonatal risks associated with fetal scalp electrode use were low (injury to scalp 1.2% and cephalohaematoma 1.0%).

[Correlation between fetal scalp samples and umbilical cord samples]. / Corrélation entre prélèvements au scalp fœtal et prélèvements artériels au cordon.

OBJECTIVE: The objective was to evaluate the correlation between fetal scalp base excess (BE) and umbilical cord BE. Respective value of fetal scalp pH, BE and lactate for the prediction of neonatal metabolic acidosis were also evaluated. METHODS: A retrospective monocentric study was conducted in a French tertiary care academic maternity. All the patients who had a fetal scalp sampling during labor in 2010, less than 90 minutes before delivery were included. Fetal heart rate abnormalities (FHRA) were classified by degree of severity, according to the French guidelines. The differences between fetal scalp samples and umbilical cord samples over time and in relation with the type of FHRA were analyzed for pH and BE. The differences between fetal scalp pH and cord pH over time and in relation with scalp BE were analyzed. The correlation between fetal scalp samples and cord samples for pH, BE and lactate was estimated. Receiver operating characteristics (ROC) curves for fetal scalp pH, lactate and BE to predict umbilical cord pH under 7.20 were calculated. RESULTS: Seventy-one cases were included. The difference between fetal scalp sample and cord sample was lower when the sample was made closest to delivery both for pH and BE. The gravity of FHRA was not predictive of a faster decrease of pH or BE over time. The correlation was significant for pH (r=0.23, p=0.03) between scalp samples and cord samples, as for BE (r=0.49, p=0.001) and lactate (r=0.52, p=0.001). The ROC curves for pH, BE and lactate displayed a similar pattern. CONCLUSION: Fetal scalp and umbilical cord samples, for pH, BE and lactate were significantly correlated but their respective predictive value for cord pH less or equal to 7.20 was poor.

Short-term neonatal outcome in diabetic versus non-diabetic pregnancies complicated by non-reassuring foetal heart rate tracings.

OBJECTIVE: Analysis of the impact of non-reassuring foetal heart rate patterns (FHR) and suspected foetal distress during active labour on the neonatal outcome in diabetic compared to non-diabetic mothers. METHODS: Retrospective case-control study comparing the short-term neonatal outcome including Apgar score at 5 min, and arterial/venous umbilical cord blood pH of 57 deliveries of women with different types of diabetes and 114 healthy controls. Patients were selected out of all deliveries with suspected foetal distress during active labour and performed foetal scalp pH samplings (n = 590) at the Medical University of Graz, Austria, during 2008-2009. RESULTS: Arterial pH was significantly lower in the diabetic group (7.215 versus 7.250, p = 0.007). Apgar scores ( > 8) at 5 min were similar in both groups (96.5% versus 95.6%, p = 0.566). The percentage of cases with foetal scalp blood pH <7.25 was higher in the diabetes group, but did not reach statistical significance (14.1% versus 7.1%, p = 0.166). CONCLUSIONS: Newborns of women with gestational and type 1 diabetes and non-reassuring FHR tracing have significantly lower arterial cord blood pH values without consequences on neonatal postpartum adaptation. Special attention to pathological changes in FHR patterns and to the more rapid decline in foetal pH during periods of foetal distress may be warranted in women with gestational and pre-conceptional diabetes during active labour. More frequent foetal scalp pH testing to rule out clinically relevant foetal acidosis needs to be discussed.

Effects on fetal and maternal temperatures of paracetamol administration during labour: a case-control study.

OBJECTIVE: To study the effect of paracetamol (acetaminophen) on maternal and fetal temperatures in labour. STUDY DESIGN: From a cohort of 185 women with continuous maternal axillary and fetal scalp temperature recordings in labour, 18 women treated with 1000mg paracetamol orally for pyrexia and 36 untreated controls matched for parity, cervical dilatation, and epidural analgesia were selected. Electronically stored temperature data were analysed offline post hoc. The dual temperatures recorded every 30min from 60min before (T-60) paracetamol administration (T0) until delivery, were noted. Longitudinal data were compared with Wilcoxon matched-pairs signed-ranks test and cross-sectional data with Mann-Whitney U test. Shapes of the temperature curves were compared with mixed-effect models statistics for repeated measurements. The main outcome measures were temperature changes after paracetamol. A two-tailed P<0.05 was considered significant. RESULTS: Prior to T0 maternal and fetal temperatures increased in the paracetamol group, but after T0 no significant changes (P≥0.1) were seen when compared with Wilcoxon signed-ranks test. In the control group, both temperatures increased from T-60 and onwards. Delta-temperatures (fetal minus maternal temperature) remained unchanged in both groups. Analyses of the mixed-effect models showed a significant difference (P=0.01) in the shape of fetal temperature curves between the paracetamol and control groups, but no significant difference (P=0.4) in maternal temperature curve shapes. CONCLUSION: In febrile parturients, neither maternal nor fetal temperatures dropped after paracetamol, but paracetamol halted an increasing trend and stabilised the fetal temperature. The effect of paracetamol on maternal temperature was inconclusive.

The reliability of foetal blood sampling as a test of foetal acidosis in labour.

OBJECTIVES: To establish whether foetal blood sampling for pH is a reliable test of foetal acidosis in labour by comparing paired foetal blood samples taken at a single procedure. STUDY DESIGN: We conducted a prospective study assessing 293 consecutive attempts at foetal blood sampling in labour over a four month period from February to May 2012. A total of 100 paired samples were suitable for analysis. We compared the consistency of pH results of paired foetal blood samples, evaluated cases where inconsistent results would result in conflicting clinical decisions, and explored factors associated with discordant results. RESULTS: There was a statistically significant difference between the mean pH of the two samples: 7.297 (SD 0.065) versus 7.315 (SD 0.059), p<0.0005. Of the 100 paired samples, 43 had a difference greater than the laboratory acceptable maximum analytical difference of 0.038. There was discordance between the samples in 16 cases with results crossing a decision threshold, and in 11 cases (69%) delivery was by emergency caesarean section. Inconsistent results were not associated with specific clinical factors and occurred more often with senior operators. CONCLUSION: Foetal blood sampling is considered by many as the gold standard in assessing intrapartum foetal wellbeing. We have demonstrated inconsistency of paired foetal blood pH results which suggests that foetal blood sampling should not be considered infallible.

Fetal scalp stimulation test: an adjunct to intermittent auscultation in non-reassuring fetal status during labor.

AIMS: To evaluate fetal scalp stimulation test (FSST) as an adjunct to intermittent auscultation in diagnosis of intrapartum fetal acidosis and associate result of FSST with cord blood pH and immediate neonatal outcome. MATERIAL & METHODS: This study was conducted at a tertiary hospital in India. Digital FSST was performed in seven hundred and fifty women in labor with singleton gestation ≥37 weeks, cephalic presentation and fetal heart abnormalities and/or thick meconium stained amniotic fluid. Intermittent auscultation was used for fetal monitoring during labor. The outcome measure was cord blood pH < 7.20 and neonatal morbidity. RESULTS: The non-reactive FSST is associated with lower umbilical cord blood pH, lower Apgar scores and higher asphyxia related neonatal morbidity (P-value < 0.001). The non-reactive FSST had 41% sensitivity and 84% specificity to detect pH < 7.20. The positive predictive value of FSST for fetal acidosis is 44% and negative predictive value is 83%. The likelihood ratio for acidosis with noncreative FSST is 2.57. CONCLUSIONS: Non-reactive FSST is associated with adverse neonatal outcomes. The positive and negative predictive values of FSST to diagnose fetal cord blood pH < 7.20 during labor are 44% & 83%, respectively.

Normalized spectral power of fetal heart rate variability is associated with fetal scalp blood pH.

BACKGROUND: Spectral power of fetal heart rate variability is related to fetal condition. Previous studies found an increased normalized low frequency power in case of severe fetal acidosis. AIMS: To analyze whether absolute or normalized low or high frequency power of fetal heart rate variability is associated with fetal scalp blood pH. STUDY DESIGN: Prospective cohort study, performed in an obstetric unit of a tertiary care teaching hospital. SUBJECTS: Consecutive singleton term fetuses in cephalic presentation that underwent one or more scalp blood samples, monitored during labour using ST-analysis of the fetal electrocardiogram. Ten-minute continuous beat-to-beat fetal heart rate segments, preceding the scalp blood measurement were used. OUTCOME MEASURES: Absolute and normalized spectral power in the low frequency band (0.04-0.15 Hz) and in the high frequency band (0.4-1.5 Hz). RESULTS: In total 39 fetal blood samples from 30 patients were studied. We found that normalized low frequency and normalized high frequency power of fetal heart rate variability is associated with fetal scalp blood pH. The estimated ß of normalized low frequency power was -0.37 (95% confidence interval -0.68 to -0.06) and the relative risk was 0.69 (95% confidence interval 0.51-0.94). The estimated ß of normalized high frequency power was 0.33 (95% confidence interval 0.01-0.65) and the relative risk was 1.39 (95% confidence interval 1.01-1.92). CONCLUSIONS: Normalized low and normalized high frequency power of fetal heart rate variability is associated with fetal scalp blood pH.

Fetal scalp lactate microsampling for non-reassuring fetal status during labor: a prospective observational study.

OBJECTIVE: The aim was to study the predictive value and feasibility of fetal scalp lactate microsampling in the management of non-reassuring fetal status during labor. METHODS: A prospective observational study was conducted on cord blood gas samplings from 7,617 singleton and cephalic deliveries at > or =37 weeks of gestation. In this population, 450 fetal scalp blood samples (FBS) were performed for abnormal fetal heart rate (FHR) patterns. Microvolume scalp lactate measurements were compared to scalp pH, neonatal cord blood gas parameters (pH, lactate, base deficit) and the Apgar score. RESULTS: Scalp lactate correlated significantly with scalp pH (r = -0.56, p = 0.001), umbilical artery pH (r = -0.39, p = 0.03), umbilical artery lactate (r = 0.48, p = 0.01) and umbilical artery base deficit (r = 0.51, p = 0.01), but not with Apgar scores. Using receiver operating characteristic curves, a scalp lactate cutoff value of 5 mmol/l was the most predictive for neonatal acidosis. Sampling failure with scalp lactate was inferior to scalp pH (1.3 vs. 14%, p < 0.001). CONCLUSION: Lactate microsampling in fetal scalp blood was found to be an attractive alternative to pH analysis and a useful 2nd-line tool for monitoring fetal asphyxia during labor.

Expression pattern of GATA-3 in embryonic and fetal human skin suggests a role in epidermal and follicular morphogenesis.

BACKGROUND: The transcription factor GATA-3 was recently identified as a master regulator in the specification of the inner root sheath. Additionally, it seems to play a role in skin barrier physiology. p63 binds and transactivates the GATA-3 promoter. While the expression profile of GATA-3 is delineated for the mouse, little is known about its expression in the adult human hair follicle and no studies are published about its distribution during human cutaneous embryogenesis. METHODS: We examined samples from embryonic, fetal and adult human skin for the expression of GATA-3 using immunohistochemistry. RESULTS: GATA-3 is expressed late during human skin development. Its expression pattern is comparable to the mouse and confined to the Huxley layer and inner root sheath cuticle but sparing the Henle layer. In addition, GATA-3 localizes to the spinous cell layer of the interfollicular epidermis. CONCLUSIONS: From the described expression pattern, it is highly probable that GATA-3 plays a role in follicular and epidermal morphogenesis. What the anatomically confined expression of GATA-3 to the spinous layer means biologically for the physiology of the skin is still unclear. Likewise, it still needs to be shown if GATA-3 could be exploited in the diagnosis of adnexal neoplasms.

[Fetal injuries during cesarean: frequency, risk factors and prevention]. / Plaies foetales en cours de césarienne: fréquence, facteurs de risque et prévention.

During the cesarean section, the immediate proximity of the scalpel blade to the fetus exposes this latter to possible injuries. This article aims at reflecting on the measures to be developed in the prevention of fetal injuries during the cesarean section after a bibliographical analysis of the available data. Occurring in about 1% of the cesarean cases, the fetal injuries are most often minimal and localized at the scalp or the face, rarely requiring a surgical repair. Sometimes, they can have a functional, aesthetic, psychological and forensic impact. The associated risk factors substantially are the emergency cesarean, the "cutaneous incision/delivery" delay and a T- or J-shaped uterine incision. In this article we expose simple means enabling an incision of the uterine cavity, thus minimizing the fetal risk.

Fine-tuning the diagnosis of fetal scalp cysts: the value of high-frequency sonography.

OBJECTIVE: The purpose of this series is to emphasize the importance of an exhaustive and appropriately conducted sonographic examination in the correct diagnosis of fetal cystic scalp lesions and the place of magnetic resonance imaging (MRI) in the diagnostic sequence. METHODS: Transabdominal and transvaginal 2- and 3-dimensional sonography with color and power Doppler imaging as well as 3-dimensional rendering techniques such as inversion and Doppler angiography were used. In 1 case, an MRI study was performed. RESULTS: In 1 case, the MRI missed and the different sonographic techniques correctly made the diagnosis of a meningocele. In the second case, sonography was sufficient to establish the diagnosis of an epidermal cyst. CONCLUSIONS: These 2 cases show the value of going the distance with the newly available high-frequency sonography. Ultimately, the correct diagnoses were made with the tools offered by sonography without the need for any other imaging modality.

[Fetal scalp blood sampling for pH and lactate measurement during labour]. / Surveillance foetale par mesure du pH et des lactates au scalp au cours du travail.

The wide use of continuous of fetal heart rate monitoring (FHR) since the seventies has been accompanied by an increase in cesarean delivery rates, without any decrease in cerebral palsy rate. Second line methods of fetal monitoring have been developed in order to better identify fetuses truly at risk of intrapartum asphyxia. The use of fetal scalp blood sampling (FBS) for fetal monitoring seems logical since neonatal acidosis is one of the major criteria of birth asphyxia. Studies show that the use of FBS reduces the increase in cesarean deliveries associated with the use of continuous FHR monitoring. However, FBS is invasive, non continuous and technically uneasy, with a rather high rate of failed blood samplings. Fetal scalp lactates measurement by micromethod requires a much smaller volume of blood. Although a wider assessment is required, the predictive value of fetal blood lactates seems to be similar to that of fetal scalp blood pH.

[Vacuum extractors: description, mechanics, indications and contra-indications]. / Ventouses : description, mécanique, indications et contre-indications.

The vacuum extractor, as opposed to other instruments, does not increase the fetal head diameter for vaginal delivery. Introduced half a century ago, this device is today widely used in many countries probably because of a learning-curve which is acquired quicker than for the forceps. Major benefits obtained are the flexion of the fetal head provided that the cup is correctly placed, and the compulsory rotation induced that is most useful in the conversion of occiput posterior or transverse to anterior positions. The limitations reside in the need for maternal effort at expulsion and in the fact that it is unsuitable for face presentations. Moreover, like other instruments, the vacuum extractor can be harmful and even dangerous to the mother and her fetus. Therefore, its indications and contra-indications must be respected, and its operative use mastered with as much precision as for the forceps.

Validity of methyl mercury hair analysis: mercury monitoring in human scalp/nude mouse model.

OBJECTIVE: The grafting of human scalp hair was used as a new application of this method to explore methyl mercury incorporation into human hair and to validate this model for mercury monitoring in hair. METHODS: Human scalp grafts were transplanted to athymic BALB/c nude mice. The animals were exposed to methyl mercury either as a single dose i.p. or continuously for 4 months, using ALZET osmotic pumps. The mercury concentration in hair was determined using x-ray fluorescence (XRF) spectrometry by segmental (2 mm) analysis of a single strand, and tissue concentrations were measured by cold vapor atomic absorption analysis. RESULTS: Human scalp hair grown in nude mice showed long-term persistence of human features including the expression of histocompatibility antigens (KAB 3, W 6/32, SF 1-1.1.1) and normal hair morphometry. The disposition of methyl mercury in nude mice followed a one-compartment model with a whole body elimination half-life of 6.7 days (elimination constant, k = 0.1/day). Autoradiographic studies revealed that methyl mercury was rapidly incorporated into areas of the hair follicle undergoing active keratinization. Methyl mercury concentrations in human hair transplanted onto nude mice were two orders of magnitude higher than in blood and attained a mean hair: blood ratio of 217 : 1, similar to ratios reported only in human studies. CONCLUSIONS: This study demonstrated that human hair grown on nude mice can record the level of exposure to methyl mercury and can serve as a valuable research tool to study mercury incorporation into human hair.

Intervention rates after elective induction of labor compared to labor with a spontaneous onset. A matched cohort study.

INTRODUCTION: Elective induction of labor has become a widely used procedure in obstetrics. A number of studies have shown an increased incidence of operative deliveries. The objective of this study was to evaluate the rate of interventions in our hospital, including operative delivery. METHODS: A matched cohort study in which labor of 122 electively induced women and 122 women with labor with a spontaneous onset were analyzed retrospectively. These women were matched for parity and gestational age. RESULTS: Pain relief, fetal scalp blood sampling and operative deliveries were recorded more frequently in the electively induced labor group. Cesarean delivery was found in 15% of women with induced labor, and in 1% of labors with a spontaneous onset (relative risk 18 (95% CI 2.4-132.7)). No differences were found in neonatal outcomes. CONCLUSIONS: Elective induction of labor leads to increased intervention rates during labor. The rate of cesarean delivery is high, particular in nulliparous women and multiparous women without a previous vaginal birth.

Current status of intrapartum fetal monitoring: cardiotocography versus cardiotocography + ST analysis of the fetal ECG.

Two randomized controlled trials (RCT) on intrapartum fetal monitoring with cardiotocography (CTG) only versus CTG combined with automatic ST segment waveform analysis of the fetal ECG have been performed. In altogether 6826 randomized cases, the odds ratio for operative delivery for fetal distress (ODFD) was 0.65 (95% confidence interval 0.53-0.78) and for metabolic acidosis at birth 0.39 (0.21-0.72), in favor of the CTG+ST method. CTG combined with ST analysis increases the ability of obstetricians to identify fetal hypoxia and to intervene more appropriately, resulting in an improved perinatal outcome.