Antepartum fetal monitoring

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1. 09.04.2015 1 ANTEPARTUM FETALANTEPARTUM FETAL MONITORINGMONITORING Tevfik Yoldemir MD, BBA Marmara University Department of Obstetrics and Gynecology Division of Reproductive Endocrinology and Infertility ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Two thirds of fetal deathsTwo thirds of fetal deaths occur before theoccur before the onset of labor.onset of labor. ManyMany antepartumantepartum deaths occur in womendeaths occur in women at risk forat risk for uteroplacentaluteroplacental insufficiency.insufficiency. Ideal test: allows intervention before fetalIdeal test: allows intervention before fetal death or damage from asphyxia.death or damage from asphyxia. Preferable: treat disease process andPreferable: treat disease process and allow fetus to go to term.allow fetus to go to term. ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Methods forMethods for antepartumantepartum fetal assessmentfetal assessment Fetal movement countingFetal movement counting Assessment of uterine growthAssessment of uterine growth AntepartumAntepartum fetal heart rate testingfetal heart rate testing Biophysical profileBiophysical profile DopplerDoppler velocimetryvelocimetry ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Uteroplacental insufficiencyUteroplacental insufficiency Inadequate delivery of nutritive or respiratoryInadequate delivery of nutritive or respiratory substances to appropriate fetal tissues.substances to appropriate fetal tissues. Inadequate exchange within the placenta dueInadequate exchange within the placenta due to decreased blood flow, decreased surfaceto decreased blood flow, decreased surface area or increased membrane thickness.area or increased membrane thickness. Inadequate maternal delivery of nutrients orInadequate maternal delivery of nutrients or oxygen to the placenta or to problems ofoxygen to the placenta or to problems of inadequate fetal uptake.inadequate fetal uptake. ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Theoretical scheme of fetal deteriorationTheoretical scheme of fetal deterioration Fetal well being (Nutritional compromise)Fetal well being (Nutritional compromise) Fetal growth retardation (Marginal placentalFetal growth retardation (Marginal placental respiratory function)respiratory function) Fetal hypoxia with stress (Decreasing respiratoryFetal hypoxia with stress (Decreasing respiratory function)function) Some residual effects of intermittent hypoxiaSome residual effects of intermittent hypoxia (profound respiratory compromise)(profound respiratory compromise) AsphyxiaAsphyxia DeathDeath ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Conditions placing the fetus at risk for UPIConditions placing the fetus at risk for UPI Preeclampsia, chronic hypertension,Preeclampsia, chronic hypertension, Collagen vascular disease, diabetes mellitus, renalCollagen vascular disease, diabetes mellitus, renal disease,disease, Fetal or maternal anemia, blood group sensitization,Fetal or maternal anemia, blood group sensitization, Hyperthyroidism, thrombophilia, cyanotic heartHyperthyroidism, thrombophilia, cyanotic heart disease,disease, Postdate pregnancy,Postdate pregnancy, Fetal growth restrictionFetal growth restriction 2. 09.04.2015 2 ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Fetal movement countingFetal movement counting Maternal perception of a decrease in fetalMaternal perception of a decrease in fetal movements may be a sign of impending fetalmovements may be a sign of impending fetal death.death. It costs nothing.It costs nothing. In a systematic fashion, especially in low riskIn a systematic fashion, especially in low risk populations, may detect unsuspected fetalpopulations, may detect unsuspected fetal jeopardy.jeopardy. ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Fetal movement countingFetal movement counting 3 movements in 30 minutes (Sadovsky).3 movements in 30 minutes (Sadovsky). Elapsed time to register 10 fetal movementsElapsed time to register 10 fetal movements (Moore and Piacquadio).(Moore and Piacquadio). ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Assessment of uterine growthAssessment of uterine growth General rule: fundal height in centimeters will equalGeneral rule: fundal height in centimeters will equal the weeks of gestation.the weeks of gestation. Exceptions: maternal obesity, multiple gestation,Exceptions: maternal obesity, multiple gestation, polyhydramnios, abnormal fetal lie, oligohydramnios,polyhydramnios, abnormal fetal lie, oligohydramnios, low fetal station, and fetal growth restriction.low fetal station, and fetal growth restriction. Abnormalities of fundal height should lead to furtherAbnormalities of fundal height should lead to further investigation.investigation. Accuracy: poor?Accuracy: poor? ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING When to begin testingWhen to begin testing Single factors with minimal to moderateSingle factors with minimal to moderate increased risk forincreased risk for antepartumantepartum fetal death:fetal death: 3232 weeksweeks.. Highest maternal risk factors: 26 weeks.Highest maternal risk factors: 26 weeks. When estimated fetal maturity is sufficient toWhen estimated fetal maturity is sufficient to expect a reasonable chance of survival shouldexpect a reasonable chance of survival should intervention be necessary.intervention be necessary. ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Which test to use?Which test to use? Contraction stress testContraction stress test Low incidence of unexpected fetal deathLow incidence of unexpected fetal death Increase in time, cost and inconvenienceIncrease in time, cost and inconvenience Nonstress testNonstress test Biophysical profile, modified biophysicalBiophysical profile, modified biophysical profileprofile Doppler velocimetryDoppler velocimetry ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Nonstress test (NST)Nonstress test (NST) Healthy fetuses display normal oscillations andHealthy fetuses display normal oscillations and fluctuations of the baseline FHR (Hammacher, 1966;fluctuations of the baseline FHR (Hammacher, 1966; Kubli, 1969).Kubli, 1969). Absence of these patterns was associated withAbsence of these patterns was associated with increase in neonatal depression and perinatalincrease in neonatal depression and perinatal mortality.mortality. Accelerations of the FHR during stress testingAccelerations of the FHR during stress testing correlated with fetal well being (Trierweiler, 1976).correlated with fetal well being (Trierweiler, 1976). 3. 09.04.2015 3 ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Nonstress test (NST)Nonstress test (NST) Accelerations of the FHR occur with fetalAccelerations of the FHR occur with fetal movement, uterine contractions, or inmovement, uterine contractions, or in response to external stimuli.response to external stimuli. FHR accelerations appear to be a reflection ofFHR accelerations appear to be a reflection of CNS alertness and activity.CNS alertness and activity. Absence of FHR accelerations seems to depictAbsence of FHR accelerations seems to depict CNS depression caused by hypoxia, drugs,CNS depression caused by hypoxia, drugs, fetal sleep, or congenital anomalies.fetal sleep, or congenital anomalies. ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Nonstress test (NST)Nonstress test (NST) The endpoint of the NST is the presence or absenceThe endpoint of the NST is the presence or absence of FHR accelerations within a specified period of time.of FHR accelerations within a specified period of time. Most clinicians use 2 accelerations of 15 beats perMost clinicians use 2 accelerations of 15 beats per minute (BPM) for 15 seconds in a 20minute (BPM) for 15 seconds in a 20--minute period.minute period. A healthy fetus < 32 weeks gestation may not haveA healthy fetus < 32 weeks gestation may not have the reactivity or the accelerations that meet thethe reactivity or the accelerations that meet the criteria of 15 BPM for 15 seconds.criteria of 15 BPM for 15 seconds. The more remote from term, the more likely thatThe more remote from term, the more likely that nonreactivity will be due to fetal prematurity.nonreactivity will be due to fetal prematurity. Basic Features of FH TraceBasic Features of FH Trace Baseline variability CTGBaseline variability CTG Baseline variabilityBaseline variability ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Performing the NSTPerforming the NST External monitors for contraction and FHRExternal monitors for contraction and FHR measurement applied.measurement applied. Patient in semiPatient in semi--fowler position or left lateralfowler position or left lateral tilt (to minimize supine hypotension).tilt (to minimize supine hypotension). Fetal movement is recorded.Fetal movement is recorded. ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Interpreting the NSTInterpreting the NST Reactive: 2 or more accelerations in 20Reactive: 2 or more accelerations in 20 minutes.minutes. Accelerations: an increase of at least 15 BPMAccelerations: an increase of at least 15 BPM above the baseline lasting at least 15 seconds.above the baseline lasting at least 15 seconds. Fetal sound stimulation may be used to elicitFetal sound stimulation may be used to elicit a response.a response. 4. 09.04.2015 4 ANTEPARTUM FETAL MONITORINGANTEPARTUM FETAL MONITORING Interpreting the NSTInterpreting the NST Non reactive: Less than 2 accelerations in a 20Non reactive: Less than 2 accelerations in a 20-- minute period.minute period. May extend the testing period to 40 minutes or perform aMay extend the testing period to 40 minutes or perform a backback--up test.up test. There is no universal agreement on the number ofThere is no universal agreement on the number of accelerations required to consider the test reactive