Electronic Fetal Monitoring (EFM)
Why Are We Using Electronic
CLARISSA C. KRIPKE, M.D.
Georgetown University Medical Center
In the 1960s and 1970s, continuous
electronic fetal monitoring (EFM) was introduced
with the idea that it would help clinicians
diagnose fetal hypoxia in time to prevent perinatal
neurologic damage. By the early 1990s, more
than 75 percent of the nation's birth attendants
had switched from intermittent auscultation
However, more recently, a number of systematic reviews of randomized controlled trials have been published that do not support the routine use of EFM, especially in low-risk women.2-5 The data show that neurologic abnormalities are not caused by intermittent episodes of asphyxia that commonly occur during labor and delivery. The Cochrane Collaboration2 concluded that, compared with intermittent auscultation, EFM does not reduce the rate of perinatal deaths, the rate of APGAR scores below 7 or the number of infants admitted to neonatal intensive care. Moreover, EFM was found to result in higher rates of cesarean section (relative risk: 1.33, confidence interval: 1.08 to 1.59) and total operative deliveries (relative risk: 1.23, confidence interval: 1.15 to 1.31).
The U.S. Preventive Services Task Force states that there is "fair" evidence that "routine EFM for low-risk women in labor is not recommended."3 For high-risk women, the task force states, "There is insufficient evidence to recommend for or against EFM . . ." The Canadian Task Force on the Periodic Health Examination made a similar recommendation.4 A technical bulletin from the American College of Obstetricians and Gynecologists states that either EFM or intermittent auscultation is acceptable and acknowledges the risk of increased intervention with continuous monitoring.5
Furthermore, outcomes are the same regardless of whether fetal distress is managed operatively or conservatively.6,7 Because intervention that is chosen on the basis of the fetal heart rate does not seem to improve outcomes, it is possible that we should not be monitoring by any method. Unfortunately, all of the randomized, controlled trials of EFM have compared continuous with frequent intermittent monitoring. Until we have a controlled study comparing monitored women with unmonitored women, we will continue to spend considerable health care resources without knowing whether monitoring fetal heart tones is even necessary. However, it is unlikely that this type of study will be done.
If our best evidence-based guidelines no longer recommend EFM, why are so many clinicians still using it? It seems simple to abandon a technology that has failed to live up to its promise. Nevertheless, there are educational, legal, technical and financial barriers to changing clinical practice.
First, since the advent of EFM, many nurses and physicians have not been trained in intermittent auscultation. For clinicians to feel comfortable using auscultation, more training opportunities will have to be developed.
Second, some physicians believe that EFM might still be a valuable assessment tool with better guidelines for interpreting tracings and making management decisions.8 In this issue of American Family Physician, Sweha and colleagues9 review the current literature on the interpretation of fetal heart rate monitoring. However, many studies comparing the ability of experts to agree on the interpretation of an EFM tracing have shown poor inter-rater reliability, even in controlled research settings with expert clinicians.10,11
To address this problem, the National Institutes of Health and the International Federation of Gynecology and Obstetrics have established criteria for interpreting EFM strips.12 Also, the possibility of using computer-generated interpretations to make more objective assessments is being studied.13,14 These efforts may someday produce effective methods for interpretation and clinical decision-making. Currently, no such method exists.
Third, physicians may fear that they will be vulnerable to malpractice lawsuits if they do not use EFM. The impact of changing to intermittent monitoring on malpractice claims is unknown. However, as long as patients are counseled and intermittent auscultation is performed diligently, physicians can be confident that they are following current recommendations. Furthermore, tracings are frequently used to justify claims that action should have been more aggressive or timely despite the fact that EFM has a low positive predictive value for fetal compromise.15-18
In one study,19 reviewers were given two identical tracings and antenatal histories but were told that the outcome was good in one case and poor in the other. When the outcome was poor, the reviewers were more likely to disagree with the obstetrician's interpretation and management. This study demonstrates the danger of retrospective reviews of fetal heart tracings by expert witnesses.19,20 If hospital clinical policies support intermittent auscultation, it might prove easier to defend a management decision based on a carefully documented clinical assessment rather than on an EFM tracing.
A fourth reason that physicians may favor EFM is that many hospitals are not adequately staffed to do intermittent auscultation. Studies that show intermittent auscultation to be equivalent or better than EFM had 1:1 ratios of nurses to patients and fetal heart tones were assessed every 15 to 30 minutes during the first stage of labor and every five minutes in the second stage. In one study,21 a university hospital center attempted to use intermittent auscultation as the primary method of monitoring without increasing the number of staff. Auscultation was only successfully completed in 31 of 862 patients in labor with viable fetuses. Intermittent auscultation was abandoned for most patients because the staff was not able to maintain the required 1:1 nurse-patient ratio.
Reducing cesarean section rates and equipment needs might partially offset the costs of hiring additional staff to perform intermittent auscultation. Nevertheless, routine use of intermittent auscultation is likely to be more expensive than EFM. Although no data are available to indicate whether adopting intermittent auscultation reduces costly malpractice claims, it is possible that if EFM tracings were not used retroactively to question physician judgment, reducing legal costs could make intermittent auscultation financially viable. Other solutions to the staffing problems might include hiring trained birth attendants instead of registered nurses to do the monitoring. Continuous labor support has also been shown to decrease intervention and increase patient satisfaction.22,23
Intermittent auscultation is a "high-touch, low-tech" method that lowers the number of cesarean sections performed because of fetal distress. This is safer for mothers and reduces the need for consultatation, which can disrupt the doctor-patient relationship. Family physicians are at the forefront of overcoming the challenges of implementing evidence-based guidelines. They are in an ideal position to introduce intermittent monitoring to their hospitals because they often spend a significant amount of time at their patients' bedside and usually only have one patient laboring at a time.
Dr. Kripke practices obstetrics as an instructor in the Department of Family Medicine at Georgetown University, Washington, D.C. She is a graduate of Fairfax Family Practice, a residency program of the Medical College of Virginia, Fairfax. Dr. Kripke is currently the AFP John C. Rose fellow in medical editing.
Address correspondence to Clarissa Kripke, M.D., 212 Kober-Cogan, Georgetown University Medical Center, 3800 Reservoir Rd., N.W., Washington, D.C. 20007.
Electronic Fetal Monitoring During Labor
by Becky Sisk, PhD, RN © 2002
Electronic fetal monitoring (EFM) during labor
remains a controversial procedure because it
continues the "medicalization" of
the normal birth process (McRae, 1999). The
purpose of EFM is to detect complications during
labor, particularly hypoxia, metabolic acidosis
in order to prevent brain damage (cerebral
palsy) or fetal death (Garite, 2001).
At the time EFM was introduced in the 1950s, physicians felt that its use would also reduce the cesarean birth rate because hypoxia could be more accurately diagnosed. However, there has been no significant reduction in cerebral palsy since EFM was introduced (Garite, 2001) and the cesarean rate in the U.S.
has steadily risen (Merck Manual Online, 2002).
On the plus side, the number of stillbirths during labor has been reduced to almost zero (Schifrin, 1999). Additionally, EFM is a convenient and accurate means to determine the status of a fetus. Paradoxically, though criticized as being more highly technical than necessary for a normal labor and delivery, EFM is an accurate means to determine whether the fetus remains healthy and "normal."
Forms of EFM include:
- Doppler auscultation through the mother's abdomen
- External or internal electrical fetal heart rate (FHR) monitoring. Be aware that
* Internal electrical FHR monitoring is contraindicated for fetuses with face or unknown presentation, when
placenta previa occurs, or in others who are IV positive or have genital herpes (British Columbia Reproductive Care Program, 1997).
* Abnormal rhythms and artifacts are not unusual during normal labor, so the FHR itself does not give an indication of fetal oxygenation.
* EFM yields a strip that shows both the rate and pattern of heart beats.
* Along with the uterine contraction monitor, electrical FHR monitoring gives some indication about how the
fetus is handling contractions (FDA, 2000).
- Fetal scalp sampling of the blood pH, an invasive procedure
* The normal fetal blood pH is >7.25. A pH of <7.0 indicates an urgent emergency.
* The procedure is not done if there is a history of hemophilia in the family or if the mother is HIV positive or has genital herpes (British Columbia Reproductive Care Program, 1997).
- Fetal oxygen saturation monitoring, to measure fetal oxygenation continuously during labor, another invasive procedure
* This device is used when the FHR is compromised, to determine whether the change in the FHR is affecting the fetus.
* The sensor is inserted into the uterus and rests on the fetus's cheek or temple.
* Fetal oxygen saturation monitoring can only be done with a single fetus at least 36 weeks old, a normal
vertex position (head down, face to the posterior), and a broken amniotic membrane.
Indications for EFM include:
- Vaginal birth after cesarean (VBAC) patients, to more accurately determine when a cesarean is necessary
- Any high risk pregnancy, such as a diabetic or hypertensive mother, or high risk situation such as
oligohydrammios, premature labor, post-term pregnancy.
- Any complication, such as an inaudible pulse, meconium stained amniotic fluid, hemorrhage, premature rupture of membranes, or difficult labor.
EFM has become routine in hospital settings, promoted by nurses as well as obstetricians. The question remains whether it is appropriate or desirable for all cases. Nurse midwifery education emphasizes avoiding medical intervention unless complications ensue. Yet labor nurses eagerly embrace the objective data EFM provides (Hoerst & Fairman, 2000). As with any high technology intervention, hands-on assessment remains an important part of the overall picture patients present.
Garite, T.J. (2001). Evaluating fetal hypoxia with pulseoximetry. Contemporary OB/GYN, July, 2001.
Hoerst, B.J. & Fairman, J. (2000). Social and professional influences of the technology of electronic fetal monitoring on obstetrical nursing. Western Journal of Nursing Research, 22, 475-491.
Johnson, K. (2000). Fetal pulse oximetry raises VBAC success rate. Family Practice News, May 15, 2000.
McRae, M.J. (1999). Fetal surveillance and monitoring legal issues revisited. Journal of Obstetric, Gynecologic, and Neonatal Nursing, 28, 410-419.
Merck Manual Online (2002). Management of normal labor. Retrieved June 29, 2002.
Nesbitt, B. (1999). The pitfalls of fetal monitoring, Interview with Barry Schifrin, MD, American Institute of
Ultrasound in Medicine, San Antonio, Texas, March, 1999. Retrieved June 29, 2002.
This article was taken from Volume 1, # 11 of the "Clinical Nursing Resources" newsletter.