Ob1 Lec - Noninvasiv

OB Lecture 3 - NON–INVASIVE ANTEPARTUM FETAL SURVEILLANCE USTMED ’07 Sec C - AsM Antepartum Fetal Surveillance Definition - All methods to monitor fetal well being before labor Administered : 1. age of gestation when fetal survival possible

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Electronic Fetal Heart Rate Monitoring

Non- Stress Test Basis :

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Fetal Movement Counting Simple Least Expensive Second half of pregnancy Basis :

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Compromised fetus ↓ O2 requirements by reducing activity

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( + ) correlation between maternal perception of fetal movements and movements by US scanning for 28-43 wks. Documented cessation of fetal activity warns of impending death

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Fetus with good integration of PNS, SC , brain and autonomic NS and intact myocardium will respond to FM with accelerations

Interpretation:

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Reactive – 2 FM in 20 min. , FHR accels. 15 bpm.,15 secs. , variability 6bpm. N baseline

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Non-Reactive – (-) FM, (-) acceleration w/ movement or stimulation, poor or (-)LTV, baseline N or abn.

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Uncertain Reactivity - < 2 FM in 20 min. or accels of < 15 bpm.,<15 secs., LTV < 6 bpm. Abn. Baseline

Method:

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Because of increased maternal carboxyhemoglobin levels or direct effect of nicotine on Fetal CNS

When neuro developmental center is already operative

Antepartum Fetal Surveillance Methods Non-Invasive Invasive Fetal Movement Counting Amniocenteses Non-Stress Test Chorionic Villus Sampling Contraction Stress Test Fetal Blood Sampling Biophysical Profile Scoring Doppler Velocimetry

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Temporary ↓ in FM

Most attractive and convenient “ count to 10” Performed at any convenient time Patient Left lateral , concentrate on fetal activity Evening hours, recent meal not necessary Father help in charting promote family attachment and compliance

Fetal Kick Count Chart  Contact physician if >1 hr to feel 10 movements Limitations of Fetal Movement Counting 1. Patient Comprehension and Convenience  Clear instructions mandatory  Educational attainment and socioeconomic background  Problem of compliance before advent of “ Count to 10 method” 2. Failure to anticipate certain stillbirths:  No technique can anticipate stillbirths

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Failure to detect malformations: Most fetuses w/ congenital anomalies show normal fetal movement patterns Fetuses w/CNS anomalies (hydrocephalus) or restriction of the LE (congenital hip dysplasia) ↓ FM (Rayburn, 1985)

Failure to distinguish bet multiple pregnancies:

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Technique cannot distinguish between twins on daily basis.

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Mother cannot determine which of the fetuses are less active. Drugs

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Non-reactive

Reactive Test - good fetal well being for 1 week or more in > 99% of cases. Non- Reactive Test – poor fetal outcome (perinatal death, Low 5 min. AS, late decels.) in < 20 % cases

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Uncertain Reactivity- repeat NST, back-up BPS, CST depending on clinical condition or OB judgement.

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Limitations of NST 1. Fetal Sleep State Fetal sleep state affects fetal cardioregulatory center, periodic variation in variability

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When FMC reassuring , still births may be due to acute hypoxic changes (abruptio placenta, umbilical cord compression)

Failure to detect growth abnormalities: Diminished activity only in the most severe cases of IUGR < 5h percentile ( Matthew,1975)

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Reactive

Depressant drugs: barbiturates, benzodiazepines, narcotics, methadone, alcohol  ↓ FM

Day2 of Bethamethasone administration FM ↓ 49% all values return to normal  Day4 transient effect Smoking:

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Periods of quiet sleep last for 1 hr. extend observation time to eliminate possibility of fetal sleep state OFFSET LIMITATION

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 “10-20-40” rule Extension to 90 min. improve false (+) rate

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Fetal inactivity may be prolonged up to 1 hr.

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DRUGS Increase FHR Mechanism B-adrenergic stimulation Increase Metabolic rate CNS stimulants Vagal Blockade Paracatechol Stimulants A-adrenergic blockade

Example Ritodrine Terbulatline Isoxuprine Caffeine, Thyroxine Cocaine, Ketamine Atropine Ephedrine Phentolamine

Decrease FHR Mechanisms Vagal Stimulation/SA Myocardial depressants B-sympathetic blockade CNS depressants

Example Digoxin Lidocaine Propanolol General anesthetics

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Maternal Conditions:

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Thyrotoxicosis , Hypokalemia – baseline FHR variability Maternal dehydration - ↑ FHR

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Maternal fever - ↑ fetal core temp.; ↑ FHR Fetal Conditions:

Test Reliability of CST

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Congenital Anomalies –heart block, anencephaly Gestational Age: “Physiologic non-reactivity” NST in preterm infant :

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15bpm amplitude not typical < of organized fetal arousal states (state F) common quiet sleep states (state 1F) Low amplitude decelerations seen with FM FHR ↓ in both rest and activity periods with↑ in AOG

Extend testing time and modifying criteria to 10 bpm/accelerations reduce False (+) rate of NST.

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NICHD ,1997 Research Guidelines for Interpretation of FHR:  < 32 weeks –accelerations in preterm fetus is >/= 10 bpm. , >/= 10 secs. Poor predictor of chronic asphyxia: non- visualization of Amniotic Fluid

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Biophysical Profile Scoring Basis:  Hypoxia Cascade Fetal CNS centers FT Cortex/subcortical (tone) area FM Cortex-nuclei (movement) FB 4th ventricle (breathing) FHR Post. (heart rate) Hypothalamus medulla

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must be combined with BPS or AFV measurement Clinical Efficacy of NST High False (+) Rate  80%

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Non-Reactive Test FURTHER EVALUATION (BPS , CST)

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Same with NST , 20 min. recording of FHR and uterine activity. (-) Uterine contractions : 1. IV Oxytocin 3 cxns. In 10 mins. 2. Nipple stimulation ( cost-effective , shorter testing time.

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1 nipple x 2 min. , rest 5 min.

Interpretation of CST

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Negative – (-) Late decelerations or significant variable decelerations Positive – Late decelerations ff. by 50% or > if frequency is < 3 in 10 min. Equivocal Suspicious – Intermittent late or significant VD present in one contraction

Variable Fetal Breathing

Fetal Tone Fetal Heart Rate AFV

Unsatisfactory - < 3 cxns. In 10 min. or uninterpretable trace

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8/10 N AF 8/8

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Limitations of CST Same limitations as NST Limited application :  Multiple Pregnancy  Preterm Labor  Hx. Of Uterine Rupture  Placental Abnormalities  Classical CS scar

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curvilinear scanner Initial survey: a. Fetal #,lie ,position b. Placenta c. Fetal morphometric data ( BPD,AC,FL) d. Gen. Survey Fetal Tone, Fetal Movement, Breathing, AFV combined with NST for Full BPS , (-) NST Modified Biophysical Profile Scoring

Interpretation Normal Nonasphyxiated Normal Nonasphyxiated Chronic fetal asphyxia suspect Possible fetal asphyxia

Possible fetal asphyxia Almost certain asphyxia

0 to 2 CST (-)

  Amniotic Fluid Volume

Score 0 < 30 sec. Of fetal breathing movements in 30 mins. 2 or < gross body movements in 30 min. observation Semi or full limb extension w/ no return or slow return to flexion (-) accelerations or < 2 Of FHR in 20 min. AF pocket < 1 cm. In 2 planes

BPS Interpretation

BPS Score 10

8/10 ↓ AF

CST (+)

Hypoxia

requires a period of time before alterations become visible Amniotic Fluid Volume – Fetal compensatory mechanism  Blood flow directed to essential organs (Brain, Heart, Adrenals) non-essential organ (Kidney)

Score 2 30 sec. Sustained Breathing Movements In 30 min. 3 or > Gross Body Movements in 30 min. Simultaneous limb and Trunk movements 1 episode of motion of a limb fr. Position of flexion to ext. w/ return FHR accels 15/bpm. Lasting for 15 secs. W/ FM for 20 min. AF pocket 1 cm. In 2 planes

Fetal Movements

Equivocal Hyperstimulatory – FHR decels. in cxns. > 2 min. or > 90 secs.

20-21 wks 24 wks

Methodology:

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Methodology:

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Marginally compromised fetus w/ limited O2 reserve and limited placental function manifest w/ late decelerations when subjected to uterine contractions.

Embryogenesis

7.5-8.5 wks 9 wks

Two categories: 1. Acute biophysical variables: altered immediately in the presence of fetal hypoxemia FB, FT,FM, HEART RATE (NST) 2. Chronic Biophysical Variables:

Contraction Stress Test Basis:

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(+) CST poor predictive value < 35% Management depend on: 1. age of gestation – Preterm , BACK-UP BPS or Doppler. Term or Post term DELIVER 2. Maternal Condition

Management (-) indication for delivery weekly testing DM 2 x a week (-) indication for delivery Rpt. Test /protocol DELIVER AF abn. DELIVER <36 wks. N AF Cx favorable Deliver, if < 36 wks. LS ration<2 ,Cx unfavorable , rpt.test in 24 hrs. , rpt. Test < Deliver >6 Observe Rpt.test same day < 6 deliver DELIVER

Modifications in BPS

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Selective use of NST when all other 4 variables are normal Substitution of AFI for vertical pocket NST/AFI – complete BPS for abn. NST or AFV BPS & Placental Grade – scoring 3 for intermediate variable VAS

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Timing and Frequency of BPS

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Polyhydramnios

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Time and frequency variable Individualized approach  “ Disease specific testing “ Testing not started at AOG where active intervention not possible More immature fetus more abnormal score to warrant delivery

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Maternal Diseases w/ polyhydramnios (DM, Multiple Pregnancy, Hydrops) cannot be assessed because no score,only in oligohydramnios Inability to provide an estimate of fetal reserve

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Take into consideration maturation of CNS centers

Limitations of BPS

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Fetal rest activity cycles:

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Fetus variation in sleep states average 20-30 min. more pronounced with fetal maturity

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REM stage – FB present 30-75% of time, apnea pds. brief, GBM more frequent, FT diminished

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Non- REM –FB 14- 35% ,apnea pds. long so that if < 30 min. observation of absent FB may not be due to hypoxia FT increased, GBM diminished

Maternal Glucose level:

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Waxing and waning of BPS parameters in sustained hypoxemia indistinguishable fr. N BPS activities. This is because of fetal compensation & resetting of sensitivity. Sudden insult (abruptio), superimposition of 2nd insult ( uterine cxns.)

Test Reliability:

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Corrected Perinatal Mortality Rate: 0 – 26.4/1000 False (-) rate : 0.078-2.28 The average interval between last normal score and fetal death was 3.62 days (placental & cord accidents)

Doppler Velocimetry

↑ incidence of FB after meals. ↑ in FB in the 2nd. & 3rd hr. after a 800kcal. Meal during the last10 wks. of pregnancy

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No association with meals and incidence of GBM and FT. Gestational Age:

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FB seems to ↑ with advancing AOG 24-28 wks. –14% of time , 19 wks- 6%, 10 wks- 2% GBM & FT – move more often at earlier AOG , more sporadic and shorter

Alcohol and Smoking:

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FB– inhibited by alcohol , 20 oz. Of alcohol in healthy pregnant women inhibit FBM x 3hrs not reversed by glucose Smoking –controversial

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Doppler Shift

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Spectral analysis: 1. Quantification of flow – unreliable

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2 cigarettes ↓ FB ↓ in rate but not incidence Nicotine – effect on uterine vasculature causing fetal hypoxemia, direct effect on fetal respiratory drive GBM & FT – not affected by Smoking and Alcohol

Doppler wave form analysis – waveform from an arterial source represent arterial velocity waveform and is configured by upstream and downstream circulatory factors.

Labor:

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FB – initial fall in the rate with Braxton Hicks cxns. With ↑ after

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incidence ↓ during last 3 days prior to onset of labor and during latent phase, abolished during active phase GBM & FT – no effect

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Drugs ↓ FBM Anesthetics halothane, thiopental Barbiturates Narcotics – morphine Benzodiazepines Prostaglandin Pancuronium

↑ FBM Cathecolamines adrenalin, B mimetics Adenylcyclase inhibitors Prostaglandin synthetase inhibitors –indomethacin Doxapram

Drugs – Fetal Movement Drug Effect Inhalational anesthetics Abolition of FM (Halothane) Neuromuscular Blocking Abolition of FM Agents (pancoronium) Narcotics Reduced FM Neuroepileptics Variable effect Steroids Transient decrease Drugs – Effect on FT Drug Effect Neuromuscular Blocking Agents ↓ in flexor tone Phenobarbital & Benzodiazepines ↓ in flexor tone Narcotics to the mother (-) effect

Wave Form Analysis Arterial Umbilical MCA Uterine Aorta Renal Artery Internal Carotid Artery

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Venous Ductus Venosus Inferior Vena Cava

Other Coronary sinus Coronary arteries Pulmonary artery

Limitations of Doppler Velocimetry 1. Use as a primary antepartum surveillance test limited ( IUGR, DM,SLE, APAS ) o ALERT signal of possibility of fetal compromise associated with placental pathology o Utilize other tests ( BPS, NST, CST) o Beginning of a spectrum NOT a pt. Where morbidity appears o Mean duration of Dx. Of AEDV to onset of fetal distress 6-8 days

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High quality equipment and trained personnel

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Drugs:

Inability to predict stillbirths related to acute changes in maternal fetal status (placental and cord accidents)

Drug Terbutaline & Ritodrine MgSO4 Steroids: Dexamethasone Betamethasone

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↓ PI in MCA

Interpretation and Management Guidelines o Umbilical Artery Doppler weekly

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Effect ↓ S/D ratio UA, Uterine Artery ↓ MCA indices

Abn. Doppler studies useful in determining frequency of other tests Abn. Doppler studies < 32 weeks look for other evidences of fetal compromise > 32 weeks, prior to term deteriorating Doppler studies (AEDV, REDF) may be indication for delivery. *** Take into consideration ALL clinical factors

Umbilical Artery

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CT Significant ↓ in CS for fetal distress (-) effect on perinatal mortality

Umbilical Artery Flows

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Cochrane Pregnancy and Childbirth Group, 2002 11 RCT’s N = 7000

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HR with doppler vs. HR w/o Doppler Results:

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↓ perinatal deaths (OR .71, 95%CI 0.50 – 1.01)

fewer induction of labor (OR .83 95% CI .74-. 93) • fewer hospital admissions (OR .56 95% CI .43 -.72) Conclusion:  Use of umbilical doppler in HR pregnancies improve outcome and reduce perinatal deaths

Conclusion 1. Methods and Limitations 2. NO tests superior 3. INTEGRATE whole clinical picture !!

- fin AsM [email protected]