Intrapartum fetal surveillance

Electronic fetal monitoring (EFM) is the recommended method of intrapartum fetal surveillance for high-risk pregnancies. The cardiotocogram (CTG) trace forms a central piece of documentary evidence in medico-legal cases related to intrapartum hypoxia and birth asphyxia. Cardiotocography was introduced in 1960s as a screening tool with the view to reduce fetal hypoxic brain injury and cerebral palsy rates. However, its positive predictive value for intrapartum fetal hypoxia is as low as 30%, with false positive rate of around 60%. Since its introduction in obstetric practice there has been an increase in intrapartum caesarean section and operative delivery rates, but there has been no demonstrable reduction in occurrence of cerebral palsy or intrapartum fetal deaths. The low specificity of CTG for detection of fetal hypoxia therefore necessitates confirmatory tests such as fetal scalp blood sampling (FBS) or analysis of fetal electrocardiography. The National Institute for Health and Clinical Excellence (NICE) recommends continuous intrapartum fetal monitoring with CTG for high-risk pregnancies and storing the CTG electronically for at least 25 years for medicolegal purposes.It is mandatory that all healthcare professionals who are responsible for the care of women in labour are adequately trained and assessed on pathophysiology of fetal heart rate (FHR) changes in labour to improve interpretation of CTG and avoid adverse maternal and/or fetal outcomes.Confidential enquiries into intrapartum morbidity and deaths have shown that the four main contributors to poor perinatal outcomes are – an inability to interpret CTG by the health professionals, a failure to incorporate the overall clinical condition, a failure to communicate or escalate, and delay in taking appropriate action. In this article we discuss three cases, two of which led to adverse perinatal outcomes. The key learning points and risk management issues relevant to the cases are also discussed.     

Intrapartum fetal surveillance

The course of labour is one of the most hazardous journeys one ever undertakes. The uterine contraction of labour subjects the fetus to a possible risk of hypoxic injury due to repeated cord compression or reduction of retro-placental perfusion. If the hypoxia is prolonged and/or severe, babies are at risk of either being born with a disability (physical or mental) or of dying during labour. Detection of fetal compromise should be followed by appropriate and timely intervention to reduce the incidence of intrapartum fetal deaths and neurological sequel related to birth asphyxia. Neonates who develop grade II or III hypoxic ischaemic encephalopathy due to birth asphyxia have a high risk of death or neurological sequel (up to 50%) that leads to major motor cognitive impairment (i.e. cerebral palsy). This article will discuss the principles of intrapartum fetal surveillance and highlight the areas of shortfall, and suggest actions that could be pursued to reduce avoidable morbidity and mortality.     

Intrapartum fetal death

Among the 18,394 children, who have been born at the Obstetric Department of the University of Innsbruck, Austria, from 1976 to 1984, 16 intrapartum deaths have been observed. Eight of these who have been vaginally delivered showed anomalies of presentation, three were anencephali, the others were singularities. There was an impressive improvement in the course of the years, but also in comparison with international results. In bur eyes, the consequence of this study is the avoiding of preterm births, an increased use of the caesarean in preterm infants with anomalies of presentation and the intensive observation intrapartum combined with a human background.     

Intrapartum fetal surveillance

Intrapartum hypoxia was thought to contribute to the incidence of cerebral palsy, seizures and mental retardation. Electronic fetal monitoring was expected to prevent or reduce this incidence. Electronic fetal monitoring has a high false positive rate and fetal blood sampling, which is an invasive procedure, only allows an intermittent assessment. Efforts are being made to improve fetal heart rate analysis and clinical management. Fetal pulse oximetry, fetal electrocardiogram waveform analysis and the intermittent measurement of lactate levels by fetal blood sampling may become established as an adjunct to electronic fetal monitoring.     

Intrapartum fetal surveillance

Electronic fetal monitoring (EFM) is the recommended method of intrapartum fetal surveillance for high risk pregnancies. Despite the questions about its efficacy and controversy regarding increased rates of operative delivery associated with its use, continuous cardiotocography (CTG) remains the predominant method of intrapartum fetal monitoring. The CTG trace also forms a central piece of documentary evidence in medico-legal cases related to intrapartum hypoxia and birth asphyxia.Although CTG is sensitive in detecting abnormalities of fetal heart rate (FHR), its specificity for detection of fetal hypoxia remains low and therefore confirmatory tests such as fetal scalp blood sampling (FBS) or analysis of fetal electrocardiography (ECG) become necessary. Due to the rising costs of litigations related to birth asphyxia and increasing complexity of obstetric patient populations, it has become absolutely mandatory that all health professionals responsible for the care of women in labour are trained adequately in interpretation and documentation of CTG traces, as well as the guidelines for actions based on the assessment of the trace and overall clinical situation.Confidential enquiries have always pointed to factors such as inability to interpret traces, failure to incorporate the clinical situation, delay in taking appropriate action and poor team working as contributors to adverse perinatal outcomes. In this article we discuss three case scenarios of adverse maternal and perinatal outcomes due to failure to adhere to basic principles of fetal monitoring and recommended actions as per the national guidelines. The key learning points and risk management issues are also discussed.     

Intrapartum fetal monitoring today

The literature on intrapartum fetal monitoring is reviewed emphasizing the pathophysiology, and current practice guidelines are discussed. FHR monitoring, ancillary tests, and investigational modalities are considered.     

Intrapartum fetal cardiac arrhythmias.

Fifteen cases of fetal cardiac arrhythmia were detected by direct fetal electrocardiogram (FECG) during intrapartum fetal monitoring. The frequency of arrhythmia of 12.4/1000 monitored births. Thirteen of the arrhythmias were supraventricular. Atrial bigeminy was the most commonly observed arrhythmia, followed by atrial trigeminy. Two cases of ventricular arrhythmia were noted, one of which was a case of ventricular tachycardia. Arrhythmias were not related to drug treatment or to stage of labor. Variable decelerations occurred in association with arrhythmias in 73% of the cases. There were no nuchal cords seen at delivery, nor were there any instances of intrapartum fetal distress, fetal acidosis, or low Apgar scores associated with any arrhythmia. All arrhythmias resolved spontaneously without treatment. The neonatal course was uncomplicated in all cases. Intrapartum fetal arrhythmia is best detected by direct FECG. Appropriate management should include close observation for ominous fetal heart rate (FHR) patterns and fetal acid-base-studies. At present, there is no indication for drug treatment of intrapartum arrhythmia.     

Intrapartum fetal heart rate monitoring

Intrapartum fetal heart rate monitoring is commonly used to evaluate fetal status in labor, despite a lack of convincing randomized studies to support its use. The National Institutes of Health have helped standardize fetal heart rate monitoring terminology with their 1997 task force report, which will aid clinicians and scientists in their goal of providing quality care and research. The American College of Obstetricians and Gynecologists has recommended the term nonreassuring fetal status for electronic fetal monitor patterns that are not normal; however, Vanderbilt continues to use the terms fetal stress and fetal distress, using specific criteria for each. The approximately 30% of fetal heart rate tracings labeled as fetal stress (or nonreassuring fetal status) can be evaluated further by the use of fetal pulse oximetry, a new technology currently under evaluation in this country.     

Intrapartum fetal monitoring by electrocardiography

To study the diagnostic values of intrapartum fetal electrocardiography (FECG) and cardiotocography (CTG), 68 patients in labor were monitored at random. One-min Apgar score was chosen as the gold standard. The specificity (87.1%) and accuracy (86.8%) of FECG were found better than those of CTG (54.5% and 57.4% respectively). Fetal hypoxia and acidosis was firstly manifested by shortened P-R interval, FHR deceleration and increase in the T wave amplitude. It suggested that FECG can be a reliable diagnostic method following CTG screening.     

Intrapartum drainage of fetal pleural effusion

Our objective was to describe our experience with intrapartum thoracocentesis in fetuses with severe bilateral pleural effusion. We describe the outcome of four consecutive cases of fetal pleural effusion due to chylothorax that were managed by intrapartum thoracocentesis. These fetuses were not candidates for pleuro-amniotic shunting either because of the need for prompt delivery (three fetuses) or because of advanced gestational age (one fetus). Thoracocentesis was performed in the operating theatre under ultrasound guidance prior to Caesarean delivery. Gestational age at the time of diagnosis and thoracocentesis ranged between 26-34 weeks and 31-34 weeks respectively. Bilateral thoracocentesis was performed in two fetuses and unilateral in the remaining two fetuses. All four infants were born in a relatively good condition; however, all eventually required intubation, ventilation and chest tubes. Chest tubes were introduced between 2 h and 5 days after delivery in three infants, and immediately after birth in one infant who was hydropic. Two infants survived and are developing normally. One infant died from sepsis following successful pleurodesis and one from aspiration on day 51. Our conclusions are that intrapartum thoracocentesis seems to be a relatively simple procedure, that allows newborns with pleural effusion, to breathe spontaneously or be more easily ventilated. This in turn, reduces the need to introduce chest tubes in an emergency situation.