Proposed cutoff for fetal scalp blood lactate in intrapartum fetal surveillance based on neonatal outcomes: a large prospective observational study.

OBJECTIVE: Determination of lactate in fetal scalp blood (FBS) during labour has been recognised since the 1970s. The internationally accepted cutoff of >4.8 mmol/l indicating fetal acidosis is exclusive for the point-of-care device (POC) LactatePro™, which is no longer in production. The aim of this study was to establish a new cutoff for scalp lactate based on neonatal outcomes with the use of the StatstripLactate® /StatstripXpress® Lactate system, the only POC designed for hospital use. DESIGN: Observational study. SETTING: January 2016 to March 2020 labouring women with indication for FBS were prospectively included from seven Swedish and one Australian delivery unit. POPULATION: Inclusion criteria: singleton pregnancy, vertex presentation, ≥35+0 weeks of gestation. METHOD: Based on the optimal correlation between FBS lactate and cord pH/lactate, only cases with ≤25 minutes from FBS to delivery were included in the final calculations. MAIN OUTCOME MEASURES: Metabolic acidosis in cord blood defined as pH <7.05 plus BDecf >10 mmol/l and/or lactate >10 mmol/l. RESULTS: A total of 3334 women were enrolled of whom 799 were delivered within 25 minutes. The areas under the receiver operating characteristics curves (AUC) and corresponding optimal cutoff values were as follows; metabolic acidosis AUC 0.87 (95% CI 0.77-0.97), cutoff 5.7 mmol/l; pH <7.0 AUC 0.83 (95% CI 0.68-0.97), cutoff 4.6 mmol/l; pH <7.05 plus BDecf ≥12 mmol/l AUC 0.97 (95% CI 0.92-1), cutoff 5.8 mmol/l; Apgar score <7 at 5 minutes AUC 0.74 (95% CI 0.63-0.86), cutoff 5.2 mmol/l; and pH <7.10 plus composite neonatal outcome AUC 0.76 (95% CI 0.67-0.85), cutoff 4.8 mmol/l. CONCLUSION: A scalp lactate level <5.2 mmol/l using the StatstripLactate® /StatstripXpress® system will safely rule out fetal metabolic acidosis. TWEETABLE ABSTRACT: Scalp blood lactate <5.2 mmol/l using the StatstripLactate® /StatstripXpress system has an excellent ability to rule out fetal acidosis.

Could a multidisciplinary regional audit identify avoidable factors and delays that contribute to stillbirths? A retrospective cohort study.

BACKGROUND: The annual rate of stillbirth in Sweden has remained largely unchanged for the past 30 years. In Sweden, there is no national audit system for stillbirths. The aim of the study was to determine if a regional multidisciplinary audit could help in identifying avoidable factors and delays associated with stillbirths. METHODS: Population-based retrospective cohort study. SETTINGS: Six labour wards in Stockholm County. PARTICIPANTS: Women delivering a stillbirth > 22 weeks of gestation in Stockholm during 2017. INTERVENTION: A multidisciplinary team was convened. Each team member independently assessed the medical chart of each case of stillbirth regarding causes and preventability, level of delay, the standard of healthcare provided, the investigation of maternal/foetal diseases and if any recommendations were given for the next pregnancy. A decision was based on the agreement of all five members. If no agreement was reached, a reassessment of the case was done and the medical record was scrutinized again until a mutual decision was made. Primary outcomes: The frequency of probably/possibly preventable factors associated with a stillbirth and the level of delay (patient/caregiver). SECONDARY OUTCOMES: The causes of death, the standard of antenatal/intrapartum/postpartum care, whether a summary of possible causes of the stillbirth was made and if any plans for future pregnancies were noted. RESULTS: Thirty percent of the stillbirths were assessed as probably/possibly preventable. More frequent ultrasound/clinical check-ups, earlier induction of labour and earlier interventions in line with current guidelines were identified as possibly preventable factors. A possibly preventable stillbirth was more common among non-Swedish-speaking women (p = 0.03). In 15% of the cases, a delay by the healthcare system was identified. Having multiple caregivers, absence of continuity in terms of attending the antenatal clinic and not following the basic monitoring program for antenatal care were also identified as risk factors for a delay. CONCLUSION: A national/regional multidisciplinary audit group retrospectively identified factors associated with stillbirth. Access to good translation services or a more innovative approach to the problem regarding communication with mothers could be an important factor to decrease possible patient delays contributing to stillbirths. TRIAL REGISTRATION: NCT04281368 .

Slow-release vaginal insert of misoprostol versus orally administrated solution of misoprostol for the induction of labour in primiparous term pregnant women: a randomised controlled trial.

OBJECTIVE: To compare the World Health Organization (WHO) recommended orally administrated dosage of misoprostol (25 µg) with a vaginal slow-release (7 µg/hour) insert of misoprostol regarding time from induction to delivery and safety of the method. DESIGN: Open label, Randomised controlled trial (RCT). SETTING: Delivery ward at a secondary referral hospital in Stockholm, Sweden, from 1 October 2016 to 21 February 2018. POPULATION: One hundred and ninety-six primiparous women with singletons in cephalic presentation at ≥37 weeks of gestation and with a Bishop score of ≤4. METHODS: Women were randomised to an oral solution of misoprostol (Cytotec® n = 99) or vaginal slow-release misoprostol (Misodel® [MVI] n = 97). MAIN OUTCOME MEASURES: Primary outcome: time from induction to vaginal delivery. SECONDARY OUTCOMES: mode of delivery; proportion of vaginal deliveries within 24 hours (VD24); neonates with an Apgar score of <7 at 5 minutes; pH < 7.10; postpartum haemorrhage (PPH) of >1000 ml; hyperstimulation; and women's delivery experience (VAS). RESULTS: There was no difference in the time to delivery [corrected] (median 21.1 hours in the MVI group and 23.2 hours in the oral group; Kaplan-Mayer log rank P = 0.31). There was no difference regarding the proportion of VD24 (50.5 versus 55.7%, P = 0.16). Hyperstimulation with non-reassuring cardiotocography (CTG) was more common in the MVI group (14.4 versus 3.0%, P < 0.01). Terbutaline (Bricanyl® ) was used more often for hyperstimulation in the MVI group (22.7 versus 4.0%, P < 0.01). There was no difference in the numbers of children admitted to the neonatal intensive care unit (NICU). CONCLUSIONS: Vaginal delivery after induction of labour (IOL) with slow-release misoprostol did not result in a shorter time from induction to vaginal delivery, compared with oral misoprostol solution, but was associated with a higher risk for hyperstimulation and fetal distress. There were no differences in mode of delivery or neonatal outcome. TWEETABLE ABSTRACT: IOL with MVI was similar to oral solution of misoprostol but hyperstimulation and fetal distress were more common.

Use of Lactate ProTM2 for measurement of fetal scalp blood lactate during labor - proposing new cutoffs for normality, preacidemia and acidemia: a cross-sectional study.

OBJECTIVE: Measurement of fetal scalp blood lactate is a supplementary tool to cardiotocography in the case of a non-reassuring tracing. Several hand-held lactate meters have been launched, all with differentials in absolute values. Therefore, the reference intervals must be calculated for each device. The internationally accepted reference interval is based on measurement with Lactate ProTM with recently got out of production. The aim of this study was to propose cutoffs for normality, preacidemia, and acidemia in fetal scalp blood for Lactate ProTM2 based on the comparison of lactate values measured with Lactate ProTM and Lactate ProTM2. DESIGN: Seven hundred one fetal scalp blood samples were analyzed simultaneously. The conversion equations were retrieved from the linear regression model. On the basis of the cutoffs for Lactate ProTM cutoffs for Lactate ProTM2 were calculated. RESULTS: The conversion equations obtained were Lactate ProTM = -0.02 + 0.68 × Lactate ProTM2 (SD: -0.09-0.07 × Lactate ProTM2) and Lactate proTM2 (LP2) = 0.03 + 1.48 × Lactate ProTM (SD: 0.16 + 0.17 × Lactate ProTM). The correlation to umbilical arterial pH was identical for the two devices (r = -0.18), whereas the correlation to umbilical arterial lactate was better for Lactate ProTM than for Lactate ProTM2 (r = 0.38, respectively, r = 0.33). The correlation to umbilical arterial lactate was dependent on time from sampling to delivery. CONCLUSION: Proposed reference values for Lactate ProTM2: scalp lactate <6.3 mmol/L = normal, no indication for intervention; 6.3-7.1 mmol/L = preacidemia, repeated testing has to be considered; > 7.1 mmol/L = acidemia, expedite delivery.

Prediction of time to spontaneous onset of labour with lactate concentration in vaginal fluid in women with suspected preterm prelabour rupture of the membranes.

OBJECTIVE: To assess whether lactate determination in vaginal fluid is associated with and can predict onset of labour for women with suspected preterm prelabour rupture of membranes (PPROMs). DESIGN: Prospective observational study. SETTING: Labour ward at South General Hospital, Stockholm, Sweden. POPULATION/PARTICIPANTS: Women with suspected PPROMs at 20-36 completed weeks of gestation (n = 81). METHODS: All women underwent a speculum examination and a test for determining lactate concentration in vaginal fluid. We used logistic regression to estimate the association between lactate concentration in vaginal fluid and time to onset of labour. MAIN OUTCOME MEASURE: Time from examination to spontaneous onset of labour (cervix > or =4 cm). RESULTS: The median time between examination and onset of labour was 13.6 hours for those with a high (> or =4.5 mmol/l) lactate concentration and 1152 hours (i.e. 48 days) for those with a low (<4.5 mmol/l) lactate concentration. For a lactate threshold of 4.5 mmol/l, the likelihood ratio for positive test (LR+) was 12.6, and LR- was 0.14 for the outcome of spontaneous onset of labour within 48 hours. CONCLUSIONS: A high lactate concentration in vaginal fluid is strongly associated with whether a woman with suspected PPROM will commence onset of labour within 48 hours. If confirmed, use of lactate ('LAC test') as a predictive test for onset of preterm labour may be an attractive tool in bedside obstetrics.

Determination of pH or lactate in fetal scalp blood in management of intrapartum fetal distress: randomised controlled multicentre trial.

OBJECTIVE: To examine the effectiveness of pH analysis of fetal scalp blood compared with lactate analysis in identifying hypoxia in labour to prevent acidaemia at birth. DESIGN: Randomised controlled multicentre trial. SETTING: Labour wards. PARTICIPANTS: Women with a singleton pregnancy, cephalic presentation, gestational age >or=34 weeks, and clinical indication for fetal scalp blood sampling. INTERVENTIONS: Standard pH analysis (n=1496) or lactate analysis (n=1496) with an electrochemical microvolume (5 mul) test strip device. The cut-off levels for intervention were pH <7.21 and lactate >4.8 mmol/l, respectively. MAIN OUTCOME MEASURE: Metabolic acidaemia (pH <7.05 and base deficit >12 mmol/l) or pH <7.00 in cord artery blood. RESULTS: Metabolic acidaemia occurred in 3.2% in the lactate group and in 3.6% in the pH group (relative risk 0.91, 95% confidence interval 0.61 to 1.36). pH <7.00 occurred in 1.5% in the lactate group and in 1.8% in the pH group (0.84, 0.47 to 1.50). There was no significant difference in Apgar scores <7 at 5 minutes (1.15, 0.76 to 1.75) or operative deliveries for fetal distress (1.02, 0.93 to 1.11). CONCLUSION: There were no significant differences in rate of acidaemia at birth after use of lactate analysis or pH analysis of fetal scalp blood samples to determine hypoxia during labour. TRIAL REGISTRATION: ISRCT No 1606064.

Association between lactate in vaginal fluid and time to spontaneous onset of labour for women with suspected prelabour rupture of the membranes.

OBJECTIVES: To assess whether lactate determination in vaginal fluid is associated with, and can predict, onset of labour for women with suspected prelabour rupture of the membranes (PROM). DESIGN: Prospective observational study. SETTING: Labour ward at Soder Hospital, Stockholm, Sweden. POPULATION: Women with suspected PROM after 34 weeks of gestation, who later had spontaneous onset of labour (n = 179). METHODS: All women underwent a speculum examination and a test for determining lactate concentration in vaginal fluid. We used logistic regression to estimate the association between lactate concentration in vaginal fluid and time to onset of labour. MAIN OUTCOME MEASURES: Time from examination to onset of labour (cervix > or =4 cm), within 24 hours and 48 hours. RESULTS: The median time interval between examination and spontaneous onset of labour was 8.4 hours for women with 'high' lactate (> or =4.5 mmol/l) and 54 hours for those with 'low' lactate concentrations (<4.5 mmol/l). Among 86 women with high lactate concentrations, 76 (88%) had started labour within 24 hours compared with 20 of 93 (22%) women with low lactate concentrations (OR 27.7, 95% CI 12.2-63.3). After checking for the effect of visible amniotic fluid, the corresponding odds were still substantially increased (OR 13.5, 95% CI 5.3-34.3). CONCLUSIONS: High lactate concentration (> or =4.5 mmol/l) in vaginal fluid can be used to predict whether a woman with suspected PROM will commence spontaneous onset of labour within 24 or 48 hours.