Electronic Fetal Monitoring

EFM is used to monitor the health of the fetus by providing information to clinicians about the fetal heart's response to uterine contractions. Obstetrics providers use their interpretation of EFM data to guide decision making during labor with the expectation of reducing perinatal morbidity and mortality resulting from fetal asphyxia. Assessment of EFM data, along with other clinical factors, can indicate the need to consider altering the course of labor by administering interventions that may include operative delivery.

Fetal monitors measure, display, and record FHR and maternal uterine activity, measured either externally or internally. For external intrapartum monitoring, a pressure transducer and one or more ultrasound transducers are placed on the mother's abdomen to measure FHR and uterine activity. For internal EFM monitoring, an electrode is applied to the fetal scalp to measure FHR and electrocardiographic (ECG) signals; an intrauterine pressure catheter (IUPC) is used to measure uterine activity and uterine pressure. Some fetal monitors also provide components for monitoring maternal parameters, such as ECG, pulse oximetry (Spo2), noninvasive blood pressure (NIBP), and temperature. (ECRI)

Fetal monitors typically include a built-in printer that provides tracings (i.e., graphic trends of FHR and uterine activity). Fetal monitors may have some or all of the following additional features: (ECRI)

Fetal monitors may be connected to an obstetrics data management system (OBDMS) to document and store EFM data. The OBDMS also acts as a central monitoring station, allowing clinicians to monitor EFM data either from the OBDMS or from patient-room workstations. Some OBDMS incorporate computer analysis of FHR signals or combined FHR and ST-segment (i.e., the heart's electrical activity immediately after the right and left ventricles have contracted) data analysis, and may elicit real-time alerts for healthcare professionals when changes "associated with fetal hypoxia" are detected. (Nunes et al.) However, a large controlled trial showed no significant benefit of the adjunctive use of ST-segment analysis in reducing a composite of neonatal outcomes or in reducing cesarean or operative vaginal deliveries in a U.S. population undergoing intrapartum EFM without ST-segment analysis. (Belfort et al.)

Centralized EFM introduces significant changes in the way patients are monitored, providing advantages and unintended adverse consequences, as illustrated in the following case study. (AHRQ) The mother had an uncomplicated term pregnancy; after her cervix was completely dilated she "pushed" for about 2 hours without any difficulty. The infant was born cyanotic and flaccid with very low Apgar scores. An arterial blood gas showed a pH of 6.70 (normal: 7.25 to 7.35), a profound acidosis. The infant required extensive resuscitation and transfer to the neonatal intensive care unit where he...