Antepartum fetal assessment

antepartum fetal assessment

1. Antepartum Fetal Assessment Presentor : Dr.Tanya Das Moderator:Dr.Dipty Shrestha

2. contents Introduction Clinical Evaluation Fetal movements Fetal Breathing Contraction Stress Testing Non Stress Test Acoustic stimulation Test Biophysical Profile Amniotic Fluid Volume Doppler Velocimetry

3. Introduction Aims of antenatal Fetal Monitoring To ensure satisfactory growth and well being of fetus throughout pregnancy To screen out the high risk factors that affect the growth of the fetus Rationality of Antenatal Fetal Tests: Tests must provide information superior to that of clinical evaluation Should be helpful in management to improve perinatal outcome Benefits of tests must outweigh the potential risks and the costs

4. Significance of Fetal Testing Between 1970-1985, 15 year duration, fetal surveillance increased from less than 1 percent in 1970 to 15 percent in 1980 Women undergoing NST had a nonsignificant decreased risk for stillbirth compared with those not tested– 3.6 versus 9.2 percent respectively A study conducted in 2003 concludedin their study of 36 preterm infants, that by the time fetal compromise is diagnosed, fetal damage has already occurred Testing for biophysical profile decreased the rate of cerebral palsy to 1.3 percent as compared to 4.7 percent in untested women.

5. Antepartum Surveillance First Trimester Clinical evaluation Ultrasound evaluation Chorionic Villus Sampling Genetic screening using fetal cell free DNA Second Trimester Amniocentesis Fetal Echocardiography Fetal Blood Sampling

6. Third Trimester Clinical Evaluation Fetal biophysical Profile Ultrasound Evaluation Non Stress test Contraction Stress Test Vibroacoustic Stimulation Test Fetal Doppler Ultrasound

7. Clinical evaluation of fetal well being First Visit Size of uterus determined: helps in estimating the correct duration of gestation Subsequent visits Maternal weight gain Blood pressure Size of uterus and fundal height

8. Antepartum Fetal Surveillance Objectives( ACOG) Prevention of fetal death Avoidance of unncessary interventions

9. Fetal Movements Passive unstimulated fetal activity commences at 7 weeks Becomes organised between 20-30 weeks of gestation Fetal movements maturation- until 36 weeks, behavioural states established

10. 4 fetal behavioural states: State 1F : quiescent state- quite sleep State 2F: Frequent Gross body movements, continuous eye movements, wider oscillation of FHR State 3F: continous eye movements in absence of body movements and no FHR acceleration State 4F: Vigorous body movements, eye movements, FHR accelerations; corresponds to awake state Mean length of quiet or inactive state-23 minutes

11. Clinical Application Cardiff ‘count 10’ formula- report if : <10 movements occur in 12 hours on 2 successive days :no movement perceived even after 12 hours in a single day 2. Daily Fetal Movement Count Three counts each of 1 hour duration (morning, noon, evening); if <10 in 12 hours(or less than 3 in each hour)

12. Fetal Breathing Chest wall movements are discontinuous in fetus : paradoxical chest wall movements >1 episode lasting >30 seconds 2 types of chest wall movements: Sighs or gasps(1-4/minute) Irregular bursts of breathing (240 cycles/minute)

13. Biophysical Profile

14. Modified Biophysical Profile First line screening tests Combined non stress test with Amniotic fluid volume Less time to perform Less expertise Excellent f etal surveillance tool False negative rate of 0.8 per 1000 and false positive rate of 1.5percent

15. Amniotic Fluid Volume Decreased uteroplacental perfusion may lead to diminished fetal renal blood flow– decreased urine production– oligohydramnios ACOG(2012a)- amnitoic fluid index <5cm or a maximum deepest vertical pocket <2cm are acceptable criteria for diagnosis of oligohydramnios

16. Contraction Stress Test Measure fetal response to transient reduction in fetal oxygen delivery during uterine contraction Test of uteroplacental insufficiency Intravenous Oxytocin used to induce contractions and FHR response is recorded Nipple stimulation can be used alternatively to induce contractions

17. Non Stress Test Test of fetal condition FHR accelerations in response to fetal movement is recorded National Institute of child health and human development fetal monitoring workshop- > 32 weeks- accelerations of 15 beats per minute for >15 seconds above baseline <32 weeks- accelerations of 10 beats per minute for > 10 seconds above baseline

18. Normal NST (ACOG and AAP 2012) ‘ 2 or more accelerations that peak at 15 beats per minute or more above baseline each lasting for 15 seconds or more in a 20 minute reading’ ( >40 minute Tracing required to conclude insufficient fetal activity accounting to fetal sleep pattern) 90% or higher false positive rate

19. Abnormal Non Stress Tests NST non-reactive for 90 minutes: 93% associated with perinatal pathology Baseline oscillation <5 beats per minute Absent accelerations Late deccelerations with uterine contractions Variable Deccelerations , if non- repetetive and brief—less than 30 seconds—do not indcate fetal compromise Repetetive variable deccelerations : at least 3 in 20 minutes or lasting more than 1 minute– suspect compromise

20. Interval Between Testing ACOG(2012a): twice weekly for women with post term pregnancy, multifetal gestation, type 1 diabetes mellitus, fetal growth restriction, gestational hypertension

21. Acoustic Stimulation Tests Loud external sounds have been used– provoke heart rate accelerations Commercially available stimulator – stimulus of 1 to 2 seconds , can be repeated upto 3 times for up to 3 seconds Positive response is defined as the rapid appearance of qualifying acceleration following stimulation

22. Doppler Velocimetry 3 fetal vascular circuits– umbilical artery, middle cerebral artery, and ductus venosus are assessed Aid in decision to interfere in growth restricted fetus

23. Umbilical Artery Velocimetry Systolic-diastolic ratio(S/D) ratio is considered abnormal if it is above 95 th centile for gestational age or if diastolic flow is decreased or reversed Absent or reversed diastolic flow– signifies increased impedance to umbilical artery blood flow Results from poorly vascularized placental villi - seen in fetal growth restriction Seen in IUGR, PIH, GDM, Post term pregnancy, Anti- phospholipid antibody syndrome

24. Middle cerebral Artery Hypoxic fetus attempts brain sparing by reducing cerebrovascular impedance and thus increasing blood flow Incresed diastolic velocity, decreased S/D ratio Seen in Rh Isoimmunisation, Fetal Anemia , D alloimmunisation and IUGR

25. Ductus Venosus Most recent Best predictor of perinatal Outcome Information about forward cardiac function Negative or reversed flow in ductus venosus is a late finding in fetal acidemia

26. Antenatal Testing Recommendations Majority of high risk pregnancies, recommended testing begin by 32 to 34 weeks Pregnancies with severe complications might require testing as early as 26-28 weeks Frequency of testing: 7 days

27. Thank you