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 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: liability and documentation

Litigation in obstetrics is common, and evidence suggests that a disturbingly high number of poor outcomes are preventable. Risk management related to fetal monitoring must include both the creation of systems to provide safer care and the mitigation of liability exposure through the use of protocols and documentation strategies that are designed to provide evidence of clinicians' attentive and appropriate care. A simplified approach to documentation is reviewed, along with suggestions for frequency of documentation, standardization of common abbreviations, and samples of concise but inclusive progress notes.     

产时电子胎心监护

产时胎儿监护对于保障胎儿分娩期安全、及时发现胎儿宫内缺氧和减少新生儿近远期不良结局的发生至关重要。产时电子胎心监护是国际普遍推荐使用的产时胎儿监护措施。正确掌握产时电子胎心监护的临床应用主要包括胎心率基本波形的定义、胎心率波形的生理病理意义以及针对胎心率波形的临床处理原则3部分内容。文章结合近年来国内外相关指南，对产时电子胎心监护做一阐述。     

Intrapartum electronic fetal monitoring and the identification of systemic fetal inflammation

OBJECTIVE: To determine if intrapartum electronic fetal heart rate monitoring (EFM) can identify the fetal in utero systemic inflammatory response or neonatal sepsis, risk factors for the development of brain injury. STUDY DESIGN: This case-control study matched cases with both histologic chorioamnionitis and funisitis (75 preterm and 63 term) to the next delivery without placental or cord inflammation by gestational age and mode of L delivery. The last 2 hours of EFM prior to delivery were reviewed by 3 perinatologists blinded to placental pathology. RESULTS: Preterm and term cases had significantly increased baseline heart rates. Term cases had significant increases in tachycardia, total and late decelerations, and nonreactivity and also had fewer accelerations. EFM parameters had sensitivity of 29-65%, specificity of 46-93%, positive predictive value of 53-80% and negative predictive value of 54-58% in identifying fetal systemic inflammation in this matched, case-control sample. Of the preterm neonates, 9 with sepsis were compared to 141 with negative cultures and were found to have a significant increase in baseline fetal heart rate and tachycardia of longer duration. CONCLUSION: Although significant associations were found, EFM lacks precision in identifying the fetal in utero systemic inflammatory response and neonatal sepsis, predisposing conditions for the development of neonatal encephalopathy.     

Abdominal electrocardiography in intrapartum fetal heart rate monitoring

Abdominal fetal electrocardiography (AFECG) as a means of intrapartum fetal heart rate (FHR) monitoring was studied in 700 consecutive labors in a small hospital. Sixty-eight pregnancies were excluded from the study because of the elective cesarean section or because labor was too short for electronic monitoring. AFECG succeeded (at least 30% of fetal heart intervals obtained) throughout labor in 99 of 632 monitored labors (16%). Ultrasound was needed in six cases (1%). The rest (527) were monitored first with the use of AFECG, and later with the use of direct FECG. The mean beat-to-beat variation of FHR (differential index) during last two hours of labor measured from AFECG signal was similar to that measured from AFECG and direct FECG. Hence the same reference values of the differential indices for both methods can be used. The mean long term variation (interval index) measured from AFECG was lower than that measured from abdominal and direct FECGs consecutively. Ultrasound is rarely needed during labor, and it should be avoided except in breech presentations, in association with low placentas and twins, if recording of AFECG fails.     

Intrapartum fetal heart rate monitoring of the extremely premature fetus

When cesarean section is not warranted because of extreme prematurity, continuous electronic fetal heart rate monitoring during the intrapartum period and in utero resuscitation of the distressed fetus are indicated, especially in cases of borderline fetal viability. Two cases are presented to illustrate the benefit of such measures when fetal distress occurs and the fetus is judged to be too small for operative intervention.     

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 heart rate monitoring in cases of cytomegalovirus infection

OBJECTIVE: Several studies have shown that abnormal intrapartum fetal heart rate patterns are the results from pre-existing fetal brain damage. We evaluated intrapartum fetal heart rate pattern of cytomegalovirus-infected fetuses and correlated the patterns with neurologic outcomes. STUDY DESIGN: Between 1991 and 2001, there were 20 cytomegalovirus-infected fetuses. We selected 40 fetuses as control subjects that were matched for gestational age and birth weight. Fetal heart rate was interpreted according to the guidelines of the National Institute for Child and Human Development. The incidence of abnormal fetal heart rate pattern and umbilical blood gases were compared between both groups. We also investigated the factors that contributed to abnormal fetal heart rate pattern in the cytomegalovirus group. RESULTS: Nonreassuring fetal heart rate patterns (prolonged deceleration and recurrent late deceleration) were observed in 8 of 20 fetuses (prolonged deceleration, 7 fetuses; recurrent late deceleration, 1 fetus) in the cytomegalovirus group and in 3 of 41 fetuses (prolonged deceleration, 1 fetus; recurrent late deceleration, 2 fetuses) in the control group (P<.05, Fisher test). Baseline fetal heart rate variability was minimal in 4 of the 7 prolonged deceleration cases in the cytomegalovirus group. Umbilical pH <7.1 was found for 1 fetus in the cytomegalovirus group. The average umbilical arterial pH values were similar in both the groups. In the cytomegalovirus group, there were no differences in the incidence of contributing factors between 8 fetuses with abnormal fetal heart rate pattern (prolonged deceleration and recurrent late deceleration) and 8 fetuses with no change. There were 3 fetuses with cerebral palsy: 2 fetuses in the no change group and 1 fetus in the prolonged deceleration group. Antigenemia was positive exclusively in 4 cases with abnormal fetal heart rate pattern (P<.05). CONCLUSION: Cytomegalovirus-infected fetuses are more likely to show abnormal intrapartum fetal heart rate patterns than low-risk control fetuses, which suggests that the perinatal detection of cytomegalovirus is necessary to distinguish hypoxic-ischemic encephalopathy.     

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.