Pathophysiological interpretation of fetal heart rate tracings in clinical practice

The onset of regular, strong, and progressive uterine contractions may result in both mechanical (compression of the fetal head and/or umbilical cord) and hypoxic (repetitive and sustained compression of the umbilical cord or reduction in uteroplacental oxygenation) stresses to a human fetus. Most fetuses are able to mount effective compensatory responses to avoid hypoxic-ischemic encephalopathy and perinatal death secondary to the onset of anaerobic metabolism within the myocardium, culminating in myocardial lactic acidosis. In addition, the presence of fetal hemoglobin, which has a higher affinity for oxygen even at low partial pressures of oxygen than the adult hemoglobin, especially increased amounts of fetal hemoglobin (ie, 180-220 g/L in fetuses vs 110-140 g/L in adults), helps the fetus to withstand hypoxic stresses during labor. Different national and international guidelines are currently being used for intrapartum fetal heart rate interpretation. These traditional classification systems for fetal heart rate interpretation during labor are based on grouping certain features of fetal heart rate (ie, baseline fetal heart rate, baseline variability, accelerations, and decelerations) into different categories (eg, category I, II, and III tracings, "normal, suspicious, and pathologic" or "normal, intermediary, and abnormal"). These guidelines differ from each other because of the features included within different categories and because of their arbitrary time limits stipulated for each feature to warrant an obstetrical intervention. This approach fails to individualize care because the "ranges of normality" for stipulated parameters apply to the population of human fetuses and not to the individual fetus in question. Moreover, different fetuses have different reserves and compensatory responses and different intrauterine environments (presence of meconium staining of amniotic fluid, intrauterine inflammation, and the nature of uterine activity). Pathophysiological interpretation of fetal heart rate tracing is based on the application of the knowledge of fetal responses to intrapartum mechanical and/or hypoxic stress in clinical practice. Both experimental animal studies and observational human studies suggest that, just like adults undertaking a treadmill exercise, human fetuses show predictable compensatory responses to a progressively evolving intrapartum hypoxic stress. These responses include the onset of decelerations to reduce myocardial workload and preserve aerobic metabolism, loss of accelerations to abolish nonessential somatic body movements, and catecholamine-mediated increases in the baseline fetal heart rate and effective redistribution and centralization to protect the fetal central organs (ie, the heart, brain, and adrenal glands), which are essential for intrauterine survival. Moreover, it is essential to incorporate the clinical context (progress of labor, fetal size and reserves, presence of meconium staining of amniotic fluid and intrauterine inflammation, and fetal anemia) and understand the features suggestive of fetal compromise in nonhypoxic pathways (eg, chorioamnionitis and fetomaternal hemorrhage). It is important to appreciate that the timely recognition of the speed of onset of intrapartum hypoxia (ie, acute, subacute, and gradually evolving) and preexisting uteroplacental insufficiency (ie, chronic hypoxia) on fetal heart rate tracing is crucial to improve perinatal outcomes.

Approaches to Preventing Intrapartum Fetal Injury

Electronic fetal monitoring (EFM) was introduced into obstetric practice in 1970 as a test to identify early deterioration of fetal acid-base balance in the expectation that prompt intervention ("rescue") would reduce neonatal morbidity and mortality. Clinical trials using a variety of visual or computer-based classifications and algorithms for intervention have failed repeatedly to demonstrate improved immediate or long-term outcomes with this technique, which has, however, contributed to an increased rate of operative deliveries (deemed "unnecessary"). In this review, we discuss the limitations of current classifications of FHR patterns and management guidelines based on them. We argue that these clinical and computer-based formulations pay too much attention to the detection of systemic fetal acidosis/hypoxia and too little attention not only to the pathophysiology of FHR patterns but to the provenance of fetal neurological injury and to the relationship of intrapartum injury to the condition of the newborn. Although they do not reliably predict fetal acidosis, FHR patterns, properly interpreted in the context of the clinical circumstances, do reliably identify fetal neurological integrity (behavior) and are a biomarker of fetal neurological injury (separate from asphyxia). They provide insight into the mechanisms and trajectory (evolution) of any hypoxic or ischemic threat to the fetus and have particular promise in signaling preventive measures (1) to enhance the outcome, (2) to reduce the frequency of "abnormal" FHR patterns that require urgent intervention, and (3) to inform the decision to provide neuroprotection to the newborn.

Episiotomy Practice and Its Associated Factors in Africa: A Systematic Review and Meta-Analysis

Background

Episiotomy, a surgical procedure that enlarges the vaginal opening during childbirth, was common practice until the early 2000s. Other sources, including the World Health Organization (WHO), advocate for the selective use of episiotomy. Episiotomy rates, on the other hand, have remained high in developing countries, while declining in developed countries. As a result, the current study sought to determine the overall prevalence of episiotomy in Africa as well as the risk factors associated with its practice.

Methods

Articles were searched in international electronic databases. A standardized Microsoft Excel spreadsheet and STATA software version 14 were used for data extraction and analysis, respectively. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) checklist was used to write this report. A random-effects meta-analysis model was used to determine the pooled prevalence of episiotomy. A heterogeneity test was conducted using I-Squared (I²) statistics. Egger's test and funnel plots were conducted to detect publication bias. Subgroup analysis was also conducted. Association was expressed through a pooled odds ratio (OR) with a 95% Confidence Interval (CI).

Result

A total of 21 studies with 40,831 participants were included in the systematic review and meta-analysis. The pooled prevalence of episiotomy practice was 41.7% [95% CI (36.0–47.4), I² = 99.3%, P < 0.001). Primiparity [OR: 6.796 (95% CI (4.862–9.498)), P < 0.001, I²: 95.1%], medical doctors- assisted delivery [OR: 3.675 (95% CI (2.034–6.640)), P < 0.001, I²: 72.6%], prolonged second stage of labor [OR: 5.539 (95% CI (4.252–7.199)), P < 0.001, I²: 0.0%], using oxytocin [OR: 4.207 (95% CI (3.100–5.709)), P < 0.001, I²: 0.0%], instrument -assisted vaginal delivery [OR: 5.578 (95% CI (4.285–7.260)), P < 0.001, I²: 65.1%], and macrosomia [OR: 5.32 (95% CI (2.738–10.339)), P < 0.001, I²: 95.1%] were factors associated with episiotomy practice.

Conclusion

In this review, the prevalence of episiotomy among African parturients was high. A selective episiotomy practice should be implemented to reduce the high episiotomy rates.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021293382, identifier: CRD42021293382.

Fetal physiology cardiotocography training, a regional evaluation

INTRODUCTION

Cardiotocography (CTG) has its limits in detecting fetal acidosis and intrapartum asphyxia. Our aim was to evaluate a CTG training programme based on fetal physiology in the Mediterranean perinatal network.

METHODS

Professionals from 41 maternity units of the Mediterranean network were invited to participate in a CTG masterclass based on fetal physiology in March 2019 and October 2019. They were asked to react to three practical cases by a physiological approach before the training course (T0), one month after (T1) and six to seven months after (T2). The mean scores were compared by using a mixed model including lapse of time to evaluation, profession of participants and level of the maternity unit as fixed effects.

RESULTS

A total of 248 professionals from 32 maternity units finally participated in the organizational audit. By using a mixed model, we found a significant improvement of the mean score at T1=6.44/10 compared to T0=4.97/10 (p<0.0001), and a significant improvement of the mean score obtained at T2=6.17/10 compared to T0 (p<0.0001). T2 scores were not significantly different from T1 scores (p=0.143).

DISCUSSION

A CTG training programme based on fetal physiology showed a significant improvement in the professionals' interpretation of CTG at short term and stable results at long term. Continuing medical education could help maintain and improve knowledge to ensure neonatal safety.