Fetal monitoring workshop 2008


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Fetal monitoring workshop 2008

  1. 1. Current CommentaryThe 2008 National Institute of Child Healthand Human Development Workshop Reporton Electronic Fetal MonitoringUpdate on Definitions, Interpretation, and Research GuidelinesGeorge A. Macones, MD, Gary D. V. Hankins, MD, Catherine Y. Spong, MD, John Hauth, MD,and Thomas Moore, MD and Gynecologists, and the Society management of intrapartum fetalIn April 2008, the Eunice Kennedy for Maternal-Fetal Medicine part- compromise.Shriver National Institute of Child nered to sponsor a 2-day workshop The definitions agreed upon inHealth and Human Development, the to revisit nomenclature, interpreta- that workshop were endorsed forAmerican College of Obstetricians tion, and research recommendations clinical use in the most recent Amer- for intrapartum electronic fetal heart ican College of Obstetricians and See related editorial on page 506. rate monitoring. Participants included Gynecologists (ACOG) Practice Bul- obstetric experts and representatives letin in 2005 and also endorsed byFrom the Department of Obstetrics and Gynecology, from relevant stakeholder groups andWashington University in St. Louis, St. Louis, organizations. This article provides a the Association of Women’s Health,Missouri; Department of Obstetrics and Gynecology, summary of the discussions at the Obstetric and Neonatal Nurses.2University of Texas Medical Branch, Galveston, workshop. This includes a discussion Subsequently, the Royal College ofTexas; Eunice Kennedy Shriver National Institute ofChild Health and Human Development, Bethesda, of terminology and nomenclature for Obstetricians and GynaecologistsMaryland; Department of Obstetrics and Gynecol- the description of fetal heart tracings (RCOG, 2001) and the Society ofogy, University of Alabama at Birmingham, Bir- and uterine contractions for use in Obstetricians and Gynaecologists ofmingham, Alabama; and Department of Obstetricsand Gynecology, University of California at San clinical practice and research. A Canada (SOGC, 2007) convened ex-Diego, San Diego, California. three-tier system for fetal heart rate pert groups to assess the evidence-For a list of workshop participants, see the Appendix tracing interpretation is also de- based use of electronic fetal monitor-online at www.greenjournal.org/cgi/content/full/112/ scribed. Lastly, prioritized topics for ing (EFM). These groups produced3/661/DC1. future research are provided. consensus documents with moreThe workshop was jointly sponsored by the American (Obstet Gynecol 2008;112:661–6)College of Obstetricians and Gynecologists, the Eu- specific recommendations for FHRnice Kennedy Shriver National Institute of Child pattern classification and intrapar-Health and Human Development, and the Society for tum management actions.3,4 In addi-Maternal-Fetal Medicine.The recommendations from the National Institute ofChild Health and Human Development 2008 T he Eunice Kennedy Shriver Na- tional Institute of Child Health and Human Development (NICHD) tion, new interpretations and defini- tions have been proposed, includ-Workshop are being published simultaneously by ing terminology such as “tachysys- convened a series of workshops inObstetrics & Gynecology and the Journal of tole” and “hyperstimulation” andObstetric, Gynecologic, & Neonatal Nursing. the mid- 1990s to develop standard- new interpretative systems usingCorresponding author: George A. Macones, MD, ized and unambiguous definitions three and five tiers.3–5 The SOGCChair, Department of Obstetrics and Gynecology, for fetal heart rate (FHR) tracings,Washington University in St Louis, MI 63110; Consensus Guidelines for Fetale-mail: maconesg@wustl.edu. culminating in a publication of rec- Health Surveillance presents aFinancial Disclosure ommendations for defining fetal three-tier system (normal, atypical,The authors have no potential conflicts of interest to heart rate characteristics.1 The goal abnormal), as does RCOG.3,4 Parerdisclose. of these definitions was to allow the and Ikeda5 recently suggested a© 2008 by The American College of Obstetricians predictive value of monitoring to five-tier management grading sys-and Gynecologists. Published by Lippincott Williams& Wilkins. be assessed more meaningfully and tem. Recently, the NICHD, ACOG,ISSN: 0029-7844/08 to allow evidence-based clinical and the Society for Maternal-FetalVOL. 112, NO. 3, SEPTEMBER 2008 OBSTETRICS & GYNECOLOGY 661
  2. 2. Medicine jointly sponsored a work- E. The characteristics to be de- L. A full description of an EFMshop focused on EFM. The goals of fined are those commonly used tracing requires a qualitativethis workshop were 1) to review and in clinical practice and research and quantitative description of:update the definitions for FHR pat- communications. 1. Uterine contractions.tern categorization from the prior F. The features of FHR patterns 2. Baseline fetal heart rate.workshop; 2) to assess existing clas- are categorized as either base- 3. Baseline FHR variability.sification systems for interpreting line, periodic, or episodic. Peri- 4. Presence of accelerations.specific FHR patterns and to make odic patterns are those associ- 5. Periodic or episodic deceler-recommendations about a system for ated with uterine contractions, ations.use in the United States; and 3) to and episodic patterns are those 6. Changes or trends of FHRmake recommendations for research not associated with uterine con- patterns over time.priorities for EFM. Thus, while goals tractions. Uterine contractions are quanti-1 and 3 are similar to the prior G. The periodic patterns are distin- fied as the number of contractionsworkshop, a new emphasis on inter- guished on the basis of wave- present in a 10-minute window,pretative systems (goal 2) was part of form, currently accepted as ei- averaged over 30 minutes. Con-the recent workshop. ther “abrupt” or “gradual” onset. traction frequency alone is a partial As was true in the prior publica- H. Accelerations and decelera- assessment of uterine activity.tion,1 before presenting actual defini- tions are generally determined Other factors such as duration, in-tions and interpretation, it is neces- in reference to the adjacent tensity, and relaxation time be-sary to state a number of assumptions baseline FHR. tween contractions are equally im-and factors common to FHR inter- I. No distinction is made between portant in clinical practice.pretation in the United States. short-term variability (or beat- The following represents termi-These were defined in the initial to-beat variability or R–R wave nology to describe uterine activity:publication1 and were affirmed period differences in the elec-and/or updated by the panel: trocardiogram) and long-term A. Normal: 5 contractions in 10 variability, because in actual minutes, averaged over a 30-A. The definitions are primarily practice they are visually deter- minute window. developed for visual interpreta- mined as a unit. Hence, the B. Tachysystole: 5 contractions in tion of FHR patterns. However, definition of variability is based 10 minutes, averaged over a it is recognized that computer- visually on the amplitude of the 30-minute window. ized interpretation is being de- complexes, with exclusion of C. Characteristics of uterine contractions: veloped and the definitions the sinusoidal pattern. • Tachysystole should always must also be adaptable to such J. There is good evidence that a be qualified as to the pres- applications. number of characteristics of ence or absence of associatedB. The definitions apply to the in- FHR patterns are dependent FHR decelerations. terpretations of patterns pro- upon fetal gestational age and • The term tachysystole ap- duced from either a direct fetal physiologic status as well as ma- plies to both spontaneous or electrode detecting the fetal stimulated labor. The clinical ternal physiologic status. Thus, response to tachysystole may electrocardiogram or an exter- FHR tracings should be evalu- differ depending on whether nal Doppler device detecting ated in the context of many contractions are spontaneous the fetal heart rate events with clinical conditions including or stimulated. use of the autocorrelation tech- gestational age, prior results of • The terms hyperstimulation nique. fetal assessment, medications, and hypercontractility areC. The record of both the FHR maternal medical conditions, not defined and should be and uterine activity should be and fetal conditions (eg, growth abandoned. of adequate quality for visual restriction, known congenital interpretation. anomalies, fetal anemia, ar- Fetal heart rate patterns are de-D. The prime emphasis in this re- rhythmia, etc). fined by the characteristics of base- port is on intrapartum patterns. K. The individual components of line, variability, accelerations, and The definitions may also be ap- defined FHR patterns do not decelerations. plicable to antepartum observa- occur independently and gen- The baseline FHR is determined tions. erally evolve over time. by approximating the mean FHR662 Macones et al Electronic Fetal Heart Rate Monitoring OBSTETRICS & GYNECOLOGY
  3. 3. rounded to increments of 5 beats Decelerations are classified as curring with 50% of uterine con-per minute (bpm) during a 10- late, early, or variable based on tractions in any 20-minute segmentminute window, excluding acceler- specific characteristics (see the Box, are defined as intermittent.ations and decelerations and peri- “Characteristics of Decelerations”).ods of marked FHR variability Variable decelerations may be ac-( 25 bpm). There must be at least companied by other characteris- General Considerations for2 minutes of identifiable baseline tics, the clinical significance of the Interpretation of Fetalsegments (not necessarily contigu- which requires further research in- Heart Rate Patternsous) in any 10-minute window, or vestigation. Some examples in- A variety of systems for EFMthe baseline for that period is inde- clude a slow return of the FHR after interpretation have been devel-terminate. In such cases, it may be the end of the contraction, biphasic oped and propagated in thenecessary to refer to the previous decelerations, tachycardia after vari- United States and worldwide.3–510-minute window for determina- able deceleration(s), accelerations Any interpretation system musttion of the baseline. Abnormal preceding and/or following, some- be based, to the greatest extentbaseline is termed bradycardia when times called “shoulders” or “over- possible, on existing evidencethe baseline FHR is 110 bpm; it is shoots,” and fluctuations in the FHR (recognizing that in some areastermed tachycardia when the base- in the trough of the deceleration. evidence is lacking). In addition,line FHR is 160 bpm. A prolonged deceleration is any system should be simple and Baseline FHR variability is deter- present when there is a visually applicable to clinical practice.mined in a 10-minute window, ex- apparent decrease in FHR from the Given that the fetal heart ratecluding accelerations and decelera- baseline that is 15 bpm, lasting response is a dynamic process, andtions. Baseline FHR variability is 2 minutes, but 10 minutes. A one that evolves over time, thedefined as fluctuations in the base- deceleration that lasts 10 minutes categories of FHR patterns are dy-line FHR that are irregular in ampli- is a baseline change. namic and transient, requiring fre-tude and frequency. The fluctuations A sinusoidal fetal heart rate pattern quent reassessment. It is commonare visually quantitated as the ampli- is a specific fetal heart rate pattern for FHR tracings to move from onetude of the peak-to-trough in bpm. that is defined as having a visually category to another over time. Variability is classified as fol- apparent, smooth, sine wave–like The FHR tracing should be in-lows: Absent FHR variability: am- undulating pattern in FHR baseline terpreted in the context of the over-plitude range undetectable. Mini- with a cycle frequency of 3–5/min all clinical circumstances, and cate-mal FHR variability: amplitude that persists for 20 minutes. gorization of a FHR tracing isrange undetectable and 5 bpm. limited to the time period beingModerate FHR variability: amplitude assessed. The presence of FHR ac-range 6 bpm to 25 bpm. Marked Quantitation of Decelerations celerations (either spontaneous orFHR variability: amplitude range The magnitude of a deceleration is stimulated) reliably predicts the ab- 25 bpm. quantitated by the depth of the nadir sence of fetal metabolic acidemia. An acceleration is a visually ap- in beats per minute (excluding tran- The absence of accelerations doesparent abrupt increase in FHR. An sient spikes or electronic artifact). not, however, reliably predict fetalabrupt increase is defined as an The duration is quantitated in min- acidemia. Fetal heart rate accelera-increase from the onset of acceler- utes and seconds from the beginning tions can be stimulated with a vari-ation to the peak in 30 seconds. to the end of the deceleration. Accel- ety of methods (vibroacoustic,To be called an acceleration, the erations are quantitated similarly. transabdominal halogen light, andpeak must be 15 bpm, and the Some authors have suggested direct fetal scalp stimulation).acceleration must last 15 seconds grading of decelerations based on Moderate FHR variability reli-from the onset to return. A pro- the depth of the deceleration or ably predicts the absence of fetallonged acceleration is 2 minutes absolute nadir in beats per minute metabolic acidemia at the time it isbut 10 minutes in duration. Fi- and duration.4 –7 These grading sys- observed. Minimal or absent FHRnally, an acceleration lasting 10 tems require further investigation variability alone does not reliablyminutes is defined as a baseline as to their predictive value. predict the presence of fetal hypox-change. Before 32 weeks of gesta- Decelerations are defined as re- emia or metabolic acidemia. Thetion, accelerations are defined as current if they occur with 50% of significance of marked FHR (previ-having a peak 10 bpm and a uterine contractions in any 20- ously described as saltatory) vari-duration of 10 seconds. minute window. Decelerations oc- ability is unclear.VOL. 112, NO. 3, SEPTEMBER 2008 Macones et al Electronic Fetal Heart Rate Monitoring 663
  4. 4. Characteristics of Decelerations Late Deceleration • Visually apparent usually symmetrical gradual decrease and return of the fetal heart rate (FHR) associated with a uterine contraction. • A gradual FHR decrease is defined as from the onset to the FHR nadir of 30 seconds. • The decrease in FHR is calculated from the onset to the nadir of the deceleration. • The deceleration is delayed in timing, with the nadir of the deceleration occurring after the peak of the contraction. • In most cases, the onset, nadir, and recovery of the deceleration occur after the beginning, peak, and ending of the contraction, respectively. Early Deceleration • Visually apparent, usually symmetrical, gradual decrease and return of the FHR associated with a uterine contraction. • A gradual FHR decrease is defined as one from the onset to the FHR nadir of 30 seconds. • The decrease in FHR is calculated from the onset to the nadir of the deceleration. • The nadir of the deceleration occurs at the same time as the peak of the contraction. • In most cases the onset, nadir, and recovery of the deceleration are coincident with the beginning, peak, and ending of the contraction, respectively. Variable Deceleration • Visually apparent abrupt decrease in FHR. • An abrupt FHR decrease is defined as from the onset of the deceleration to the beginning of the FHR nadir of 30 seconds. The decrease in FHR is calculated from the onset to the nadir of the deceleration. • The decrease in FHR is 15 beats per minute, lasting 15 seconds, and 2 minutes in duration. • When variable decelerations are associated with uterine contractions, their onset, depth, and duration commonly vary with successive uterine contractions.Interpretation of Fetal Heart tracing may move back and forth into account the entire associatedRate Patterns between categories depending on clinical circumstances.Based on careful review of the the clinical situation and manage- Category III FHR tracings areavailable options, a three-tier sys- ment strategies employed. abnormal. Category III tracings aretem for the categorization of FHR Category I FHR tracings are predictive of abnormal fetal acid–patterns is recommended (see the normal. Category I FHR tracings base status at the time of observa-Box, “Three-Tier Fetal Heart Rate are strongly predictive of normal tion. Category III FHR tracingsInterpretation System”). Although fetal acid– base status at the time require prompt evaluation. De-the development of management of observation. Category I FHR pending on the clinical situation,algorithms is a function of profes- tracings may be followed in a efforts to expeditiously resolve thesional specialty entities, some gen- routine manner, and no specific abnormal FHR pattern may include,eral management principles were action is required. but are not limited to, provision of Category II FHR tracings are in- maternal oxygen, change in mater-agreed upon for these categories. determinate. Category II FHR trac- nal position, discontinuation of la-Fetal heart rate tracing patterns ings are not predictive of abnormal bor stimulation, and treatment ofprovide information on the current fetal acid– base status, yet we do not maternal hypotension.acid– base status of the fetus andcannot predict the development of have adequate evidence at present tocerebral palsy. Categorization of classify these as Category I or Cate- Research Recommendationsthe FHR tracing evaluates the fetus gory III. Category II FHR tracings Since the last workshop, there hasat that point in time; tracing pat- require evaluation and continued not been a wealth of research onterns can and will change. A FHR surveillance and reevaluation, taking EFM. With the high penetrance of664 Macones et al Electronic Fetal Heart Rate Monitoring OBSTETRICS & GYNECOLOGY
  5. 5. Three-Tier Fetal Heart Rate Interpretation System Category I Category I fetal heart rate (FHR) tracings include all of the following: • Baseline rate: 110 –160 beats per minute (bpm) • Baseline FHR variability: moderate • Late or variable decelerations: absent • Early decelerations: present or absent • Accelerations: present or absent Category II Category II FHR tracings include all FHR tracings not categorized as Category I or Category III. Category II tracings may represent an appreciable fraction of those encountered in clinical care. Examples of Category II FHR tracings include any of the following: Baseline rate • Bradycardia not accompanied by absent baseline variability • Tachycardia Baseline FHR variability • Minimal baseline variability • Absent baseline variability not accompanied by recurrent decelerations • Marked baseline variability Accelerations • Absence of induced accelerations after fetal stimulation Periodic or episodic decelerations • Recurrent variable decelerations accompanied by minimal or moderate baseline variability • Prolonged deceleration 2 minutes but 10 minutes • Recurrent late decelerations with moderate baseline variability • Variable decelerations with other characteristics, such as slow return to baseline, “overshoots,” or “shoulders” Category III Category III FHR tracings include either: • Absent baseline FHR variability and any of the following: - Recurrent late decelerations - Recurrent variable decelerations - Bradycardia • Sinusoidal patternthis technology into obstetric prac- lationship to clinically relevant out- be focused on the effectiveness oftice, well-designed studies are comes, and the effect of duration of educational programs on EFM thatneeded to fill gaps in knowledge. patterns (eg, recurrent late deceler- include all relevant stakeholders.Areas of highest priority for re- ations with minimal variability) on Although computerized interpreta-search include observational stud- clinical outcomes. Other needed tion systems have not developed asies focused on indeterminate FHR studies include work that evaluates rapidly as anticipated, studies arepatterns, including descriptive epi- contraction frequency, strength, needed on the effectiveness of com-demiology, frequency of specific and duration on FHR and clinical puterized compared with providerpatterns, change over time, the re- outcomes. Research also needs to interpretation, including the analy-VOL. 112, NO. 3, SEPTEMBER 2008 Macones et al Electronic Fetal Heart Rate Monitoring 665
  6. 6. sis of existing data sets. Other areas 2. American College of Obstetricians and Canada, British Columbia Perinatal Gynecologists. ACOG Practice Bulle- Health Program. Fetal health surveil-for work include the development tin. Clinical Management Guidelines lance: antepartum and intrapartum con-of new comprehensive data sets for Obstetrician–Gynecologists, Num- sensus guideline [published erratumintegrating outcomes with EFM in ber 70, December 2005 (Replaces Prac- appears in J Obstet Gynaecol Can tice Bulletin Number 62, May 2005). 2007;29:909]. J Obstet Gynaecol Candigitally addressable format and re- Intrapartum fetal heart rate monitoring. 2007;29 suppl:S3–56.search on effectiveness of tech- Obstet Gynecol 2005;106:1453–60. 5. Parer JT, Ikeda T. A framework forniques supplementary to EFM, 3. The use of electronic fetal monitoring: standardized management of intrapar- the use and interpretation of cardioto- tum fetal heart rate patterns. Am Jsuch as ST segment analysis. cography in intrapartum fetal surveil- Obstet Gynecol 2007;197:26.e1–6. lance. Evidence-based clinical guideline number 8. Clinical Effectiveness Sup- 6. Chao A. Graphic mnemonic for variableREFERENCES port Unit. London (UK): RCOG Press; decelerations. Am J Obstet Gynecol 1. Electronic Fetal Heart Rate Monitor- 2001. Available at: www.rcog.org.uk/ 1990;163:1098. ing: research guidelines for interpreta- resources/public/pdf/efm_guideline_ 7. Parer JT, King T, Flanders S, Fox M, tion. National Institute of Child Health final_2may2001.pdf. Retrieved June 30, Kilpatrick SJ. Fetal acidemia and elec- and Human Development Research 2006. tronic fetal heart rate patterns: is there Planning Workshop. Am J Obstet 4. Liston R, Sawchuck D, Young D. Soci- evidence of an association? J Matern Gynecol 1997;177:1385–90. ety of Obstetrics and Gynaecologists of Fetal Neonatal Med. 2006;19:289–94.666 Macones et al Electronic Fetal Heart Rate Monitoring OBSTETRICS & GYNECOLOGY