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Christopher R. Graber, MD Salina Women’s Clinic 10 Oct 2011.

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Presentation on theme: "Christopher R. Graber, MD Salina Women’s Clinic 10 Oct 2011."— Presentation transcript:

1 Christopher R. Graber, MD Salina Women’s Clinic 10 Oct 2011

2 Background Fetal physiology Reasons to consider testing How to test What tests are available: NST, BPP, etc. Which test do I choose Test initiation and frequency How to handle non-perfect results

3 Goal of surveillance is to prevent fetal death Identification of suspected fetal compromise  opportunity for intervention Used for preexisting and developing maternal conditions, and developing fetal conditions Not good for acute events Abruption, cord events Baseline risk of IUFD

4 Perinatal mortality and gestational age. Open circles represent the cumulative probability of perinatal death × Closed circles represent perinatal mortality rate per 1000 births.

5 Fetal heart rate, level of activity, and muscular tone are sensitive to hypoxemia and acidemia Cardiotocography, real-time sono, and fetal kick counts can point to acidemia Extensive testing in both animal and human models shows correlations Ex: Redistribution of fetal blood flow  decreased renal perfusion  oligohydramnios

6 Fetal Placental Maternal

7 Antiphospholipid syndrome Hyperthyroidism (poorly controlled) Hemoglobinopathies Cyanotic heart disease Systemic lupus erythematosus Chronic renal disease Type I diabetes mellitus Hypertensive disorders

8 Pregnancy-induced hypertension Decreased fetal movement Oligo-/poly- hydramnios Intrauterine growth restriction Postterm pregnancy Isoimmunization (moderate to severe) Previous fetal demise (unexplained or recurrent risk) Multiple gestation

9 Fetal movement assessment (kick counts) Contraction stress test (CST) Breast stimulation stress test (BST) Non-stress test (CST) Biophysical profile (BPP) Modified BPP Umbilical artery Doppler velocimetry

10 Decreased fetal movement often but not always precedes fetal death Neither the optimal number of movements nor ideal duration for counting are defined 10 movements in 30,60,90 min 30 min, dark room, no distractions, try adding cold/hot drink or caffeine/calories If abnormal then further testing Usually NST as next step

11 Based on the response of fetal HR to uterine contractions Relies on premise that a suboptimally oxygenated fetus will show late decelerations due to worsening oxygenation Test is administered with at least 3 contractions of 40 sec duration in 10 min Induce contractions with breast stimulation or pitocin (0.5 mU/min, then double q 20 min)

12 Negative – No late or significant variables Positive – Late decelerations following 50% or more of the contractions (even if fewer than 3 ctx in 10 min) Equivocal – intermittent late or variable decelerations Unsatisfactory – fewer than 3 ctx in 10 min or an uninterpretable tracing

13 Preterm labor or high risk for preterm labor Preterm rupture of membranes History of extensive uterine surgery including classical cesarean delivery Known placenta previa

14 Based on premise that non-acidotic fetus will show fetal heart rate accelerations with movement (reactivity) Loss of reactivity is most commonly associated with fetal sleep cycle FHR tracing for up to 40 minutes Acoustic stimulation if sleep suspected

15 Reactive (normal) 2 or more fetal accelerations within 20 min Acceleration: 15x15 for >32 wga, 10x10 for <32 wga Nonreactive Less than 2 accelerations in 20 min Other Variable decels ok if nonrepetitive and brief (<30s) Prolonged decelerations associated with risk

16 NST combined with 4 observations on sono Fetal breathing movements Fetal movement Fetal tone Determination of amniotic fluid volume Single vertical pocket of 2cm AFI of >5cm Each component is given 0 or 2 points Total of 10 points possible

17 Normal – 8/10 or 10/10 Equivocal – 6/10 Abnormal – 4/10 or less Or oligohydramnios BPP often performed without NST as 8/8 on sono components is reassuring

18 Placental dysfunction can result in diminished fetal renal perfusion  oligohydramnios Long-term indicator of uteroplacental function Modified BPP is NST plus AFI Normal – reactive NST and AFI >5 Abnormal if either component is not normal

19 Used to assess hemodynamic components of vascular impedance Flow velocity waveforms in the umbilical artery differ in growth-restricted fetuses Extreme growth-restricted fetuses can show absent or reversed diastolic flow Correlated with small-artery obliteration in placental villi and with fetal hypoxia/acidemia

20 f d = 2(f t · cos Θ · v)/c f d = Doppler frequency shift f t = transducer frequency Θ = angle from incident beam to flow direction v = velocity of target c = speed of sound in the medium

21 S = peak systolic frequency shift value D = peak diastolic frequency shift value Ri = Resistance index Abnormal: S/D ratio > 3.0 or Ri > 0.6 Most important: note if absent or reversed end diastolic flow (AEDF or REDF)

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23 Fetal kick counts – discuss with all patients NST – reflex if decreased movement Also use for almost all other indications CST – if concerns for uteroplacental flow BPP – reflex if nonreactive NST Also use for almost all other indications Doppler – best to monitor growth restriction

24 Start testing to balance Prognosis for neonatal survival Severity of maternal disease Risk of fetal death Potential for iatrogenic prematurity due to tests Most patients should likely start at wga With severe disease or multiple risks, consider start at wga

25 NST for decreased fetal movement – prn If stable maternal medical condition – consider weekly testing (NST, BPP, mBPP) Consider twice weekly testing for Postterm pregnancy Type I DM IUGR Pregnancy-induced hypertension Consider add’l testing if medical deterioration

26 Normal results are highly reassuring NPV: 99.8% for NST, 99.9% for CST, BPP, mBPP For abnormal tests, always consider the overall clinical picture Stabilizing maternal condition may help fetus BPP of 6/10 is equivocal, repeat in 24 hours Consider maternal corticosteroids BPP of 4 or less usually indicates delivery Oligohydramnios always means more evaluation

27 Usually used only for IUGR Weekly testing if normal Consider more frequently if s/d ratio rises Consider daily testing if AEDF Consider delivery if REDF Doppler has been used on middle cerebral artery for fetal anemia (isoimm or TORCH) Higher flow = fewer RBCs

28 Normal: single pocket >2cm or AFI >5cm Evaluate for rupture of membranes If term or postterm, consider delivery If preterm, repeat fluid assessment Close monitoring recommended

29 Questions?


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