Fetal Heart Tracings M3 Clerkship Orientation

FETAL HEART TRACINGSM3 OB/GYN CLERKSHIPORIENTATIONDepartment of Obstetricsand Gynecology

MOST LAYPERSONS THINK WE CAN DO

GOALS FOR TODAYWHO – gets monitoredWHY – is this important enough to warrant a whole separate lectureWHEN – are fetuses monitoredWHERE – can this be doneWHAT is it and HOW do Iinterpret it?

WHO?Intrapartum - Women in labor (but not all) There are alternatives Some women choose not to be monitoredAntepartum monitoring Pregnant women with maternal or fetal concerns Known fetal problems

WHO –IS IT REQUIRED?How did all this start? -FHT monitoring is nearly 60years old Wasdeveloped in 1968 (Miller,et.al) -Use has only increased sincethen and is now standard ofcareIt is the most commonobstetric procedure doneand 85% of fetus havehad external fetal(ACOG practicemonitoringbulletin number 70)

THEN WHY?oResearch has shown that not shown that monitoring leads to betteroutcomes (reduction of neurologic problems in neonates)o“The goal of fetal monitoring is to prevent fetal injury resulting frominterruption of fetal oxygenation during labor or the antepartumperiod”oPossible decrease in neonatal seizures, cerebral palsy, andintrapartum death –resultant from neurologic response to lack ofoxygenationoGives information about fetal status in the moment only and has poorpositive predictive valueMILLER ET. AL

WHEN AND WHEREANTEPARTUM AND INTRAPARTUMMaternal indications: Labor Hypertensive disorders DiabetesFetal indications Growth restriction Decreased movementIn the ambulatory setting orLabor and delivery

WHAT AND HOW?The National Institute of Child Health andHuman Development (NICHD) guidelineswere created to standardize thenomenclature For appropriate patient management For standardized communication and documentation To assist with decisions about delivery and advising ourpediatric colleagues about expected outcomes

WHAT AND HOWExternal monitoring (EFM)Internal monitoring (FSE) – fetal scalp electrode

HOW DO WE DO IT?Fetoscope

DOPPLER ULTRASOUND

FETAL SCALPELECTRODE

FetusUterus

BASELINEApproximate mean FHR rounded in incrementsof 5 bpm Normal 110-160 bpm Bradycardia 110 bpm Tachycardia 160 bpmomust be measured for at least 2 minutes of a 10 minutesegment Can be indeterminate

NORMAL

NORMAL

HOW DO CONTRACTIONS FACTOR IN?Most often FETAL HEART RATE PATTERNS ARE ASSESSED IN THECONTEXT OF UTERINE CONTRACTIONSContractions are measured over a 10 minute time span, averagedover 30 minutesNormal – 5 or less in 10 minute periodTachysystole – 6 or more in a 10 minute time periodDecels are recurrent if they happen with at least ½ of the contractions

UTERINE ACTIVITYFrequency: onset of one contraction to the onset of thenext contractionDuration: onset to offset of a contractionExternal tocometer (TOCO): can access the frequency andduration but NOT the strengthIntrauterine pressure catheter (IUPC): can access thefrequency, duration and strength by measuring theintruterine pressure in mmHg

VARIABILITYFluctuations in the FHR baseline that are irregularin amplitude and frequency, measured from thepeak to the trough Marked 25 bpm Moderate 6 – 25 bpm Minimal 1 – 5 bpm Absent undetectable (straight line)

NORMAL

VARIABILITYSympathetic and parasympathetic signals modulate the FHR inresponse to moment to moment changes in the fetal PO2, PCO2, andblood pressureModerate variability reliably predicts the absence of fetal metabolicacidemia at the time it is observedMinimal or absent variability cannot confirm the presence of acidemia Fetal sleepFetal tachycardiaMedications (narcotics, general anesthesia)PrematurityCardiac arrhythmiasPreexisting neurological injury

ACCELERATIONS (ACCELS)Variation in fetal heartrate that can be seen as an increase inheartrate-Assessed based on gestational ageo 32 weeks – increase above the baseline by at least 10 bpm lastingat least 10 seconds (10x10) but less than 2 minuteso 32 weeks – increase above the baseline by at least 15 bpm lastingat least 15 seconds (15x15) but less than 2 minutes-Prolonged accelerations are 2 to 10 minutes-Longer than 10 minutes is considered a baseline change

ACCELERATIONAbrupt increase (onset to peak 30sec) in theFHR from baseline After 32 weeks: peak at least 15 beats above baselineand duration of at least 15 sec Before 32 weeks: peak at least 10 beats abovebaseline and duration of at least 10 sec Prolonged: over 2 min, if over 10 min is considered abaseline change

NORMAL

ACCELERATIONFrequently occur in association with fetal movementThe presence of fetal heart rate accelerations, either spontaneous orstimulated, reliably predicts the absence of fetal metabolic acidemiaThe absence of accelerations do not confirm the presence of acidemiaAbsence can be caused by any of the conditions that can causeminimal-absent variabilityFetal scalp stimulation or vibroacoustic stimulation can be used toprovoke accelerations

DECELERATIONS (DECELS)Come in several flavorsEarlyVariableLate

DECELERATIONEarly decelerationLate decelerationVariable decelerationProlonged decelerationRecurrent: occurs with at least 50% of ctxIntermittent: occur with fewer than 50% of ctx

EARLYDECELERATIONS –FETAL HEADCOMPRESSION-Typically mirror thecontraction-30 seconds or more fromonset to nadir

EARLY DECELERATIONGradual onset (onset to nadir 30 sec)The nadir of the decel occurs at the same time asthe peak of the contractionOccurs due to vagal (parasympathetic) stimulationof the fetal head during contractionsNot correlated with adverse outcomes and areconsidered benign

VARIABLEDECELERATIONS-CORD COMPRESSION-Sharp change in fetalheart rate with the lowestrate lasting at least 15BPM and 30 secondsDecrease is 15 BPM-The nadir is typicallyafter the peak of thecontraction-Variables can occurwithout a contraction

VARIABLE DECELERATIONSAbrupt onset (onset to nadir 30 sec)Decease at least 15 beats below baseline andlasts at least 15 secCan occur anytime in relation to a contraction orwithout a contraction

VARIABLE DECELERATIONSResponse to transient compression of the umbilicalcord Initially the thin walled vein is compressed decreasingvenous return resulting in an increase in the FHR Compression of the umbilical artery leads to an abruptincrease in peripheral vascular resistance and BP Baroreceptors increase parasympathetic outflow leadingto an abrupt decrease in FHR

LATEDECELERATIONSASSOCIATED WITHUTEROPLACENTALINSUFFICENCY- Gradual decrease infetal heart rate- Lasts 30 seconds to 2minutes-The nadir happens afterthe peak of thecontraction

LATE DECELERATIONGradual onset (onset to nadir 30 sec)The onset, nadir, and recovery occur after thebeginning, peak, and end of the contraction,respectively

LATE DECELERATIONResponse to transient hypoxemia during a uterinecontraction Contractions compress maternal blood vessels leading todecreased perfusion of the placenta If the fetal PO2 falls below a certain range there is anautonomic response Sympathetic vasoconstriction to shunt blood to vitalorgans leads to increased blood pressure Baroreceptors cause a reflex parasympathetic slowingof the FHR

SINUSOIDAL

TACHYSYSTOLE

PROLONGED DECELERATIONEither gradual or abruptDeceleration of at least 15 bpm below the baselineand lasting 2 minIf 10 min considered a baseline changeCommon causes of prolonged decels Apnea during a seizure Maternal hypotension after regional anesthesia Excessive uterine activity or uterine rupture Cord prolapse

TACHYSYSTOLEPresence or absence of FHR decels should bedocumented when noting tachysystole

ASSESSMENT – NICHD GUIDELINESCategory I – strongly predictive of normal fetal acid/base status inthat moment of assessment. No intervention is indicated.Category II – not predictive of abnormal fetal acid/base status, butdo not fit criteria for category I or III. Usually managed with closeobservation and sometimes intrauterine resuscitative effortsCategory III – associated with abnormal fetal acid/base status.Require intervention resolve the pattern as soon as possible. If there isno improvement in a short time, expeditious delivery is indicated.

NICHD 3 TIER CLASSIFICATIONCategory I Normal baseline Moderate variability Late or variable decelerations absent Accelerations and early decelerations can be present orabsentCategory II All tracings not I or IIICategory III Must have absent variability WITH recurrent late or variable decels or bradycardia for atleast 10 min

SPECIAL DESIGNATIONSReactive vs Nonreactive Relevant in outpatient setting for FETALNONSTRESS TEST For antenatal monitoring – typically lasts 20-40 minutesCONTRACTIONS STRESS TEST – response of fetus to contractions.Used when there is a concern for possible poor fetal oxygenation. Positive – presence of late decelerations associated with 50% or more of thecontractions Negative – no late or worrisome variable decelerations Equivocal/UnsatisfactoryACOG PRACTICE BULLETIN NUMBER 145

CONCLUSIONSoFHR tracing is an integral part of modern obstetric practiceoStandardized nomenclature is protective for patient and for provideroHowever, there are no studies that compare electronic fetalmonitoring and some data suggests that it increases the risk ofcesarean delivery over intermittent auscultation every 5-15 minutes,for an abnormal FHR (ACOG practice bulletin number 70)oEFM does not seem to reduce the risk of CP

CONCLUSIONSoFetal heart rate can be transiently affected bymedications and drugs Pain medications/ Narcotics Seizure prevention medicines (Magnesium sulfate) Corticosteroids Cocaine

REFERENCESAlfirevic Z, Devane D, Gyte GML. Continuous cardiotocography as a form ofelectronic fetal monitoring for fetal assessment during labour. Cochrane Databaseof Systematic Reviews 2006, Issue 3, Art No.:CD006066. DOI10.1002/14651858.CD006066 (MetaAnalysis)American College of Obstetricians and Gynecologists, Antepartum FetalSurveillance, Practice Bulletin number 145, July 2014American College of Obstetricians and Gynecologists, Intrapartum Monitoring:Nomenclature, Interpretation, and General Management Principles, PracticeBulletin number 106, July 2009Enas W. Abdulhay1, Rami J. Oweis1,, Asal M. Alhaddad1, Fadi N. Sublaban1,Mahmoud A. Radwan1, Hiyam M. Almasaeed, Review Article: Non-Invasive FetalHeart Rate Monitoring Techniques, Biomedical Science and Engineering, 2014, Vol.2, No. 3, pp53-67Miller, Lisa; Miller, David A.; Tucker, Susan M., Mosby’s Pocket Guide to FetalMonitoring, A Multidisciplinary Approach, Edition 7, Mosby, Inc., 2013Perinatology.com, Intrapartum Fetal Heart Rate ng/Intrapartum%20Monitoring.htm

CONTRACTIONS STRESS TEST -response of fetus to contractions. Used when there is a concern for possible poor fetal oxygenation. Positive -presence of late decelerations associated with 50% or more of the contractions Negative -no late or worrisome variable decelerations Equivocal/Unsatisfactory ACOG PRACTICE BULLETIN NUMBER 145