Antepartum surveillance techniques

1. Antepartum surveillance techniques Mrs. Mahdia Samaha Kony

2. Indication • Diabetes mellitus • Hypertensive disorders (chronic hypertension, preeclampsia) • Renal disease • Collagen vascular disorders • Maternal thyrotoxicosis • Severe anemia or maternal hemoglobinopathies • Isoimmunization • Prior unexplained fetal demise • Third-trimester vaginal bleeding • Premature rupture of membranes • Maternal perception of decreased fetal movements • Postdate pregnancy (>41 weeks) • Elevated maternal serum AFP (normal amniotic fluid AFP) • Abnormal or irregular fetal heart rate on auscultation • Selected fetal anomalies (e.g., gastroschisis) • Multiple gestation • Intrauterine growth restriction • Amniotic fluid abnormalities (oligohydramnios or polyhydramnios Mrs. Mahdia Samaha Kony

3. Fetal movement monitoring • A decrease in fetal movements often precedes fetal death, in some cases by several days. • Around 16–18 weeks’ gestation, most women become cognizant of fetal activity, and this perception appears to be at its maximum by 28–32 weeks. • Awareness of fetal movements will vary from patient to patient, and is also affected by other maternal, fetal, and uterine factors • In general, patients perceive about 80% of ultrasonographically visualized fetal movements. Mrs. Mahdia Samaha Kony

4. Factors influencing maternally perceived fetal movements Maternal • Activity • Obesity • Ingestion of medications or drugs that depress (e.g., methadone) or increase (e.g., cocaine) fetal movements Fetal • Behavioral states • Gestational age • Congenital anomalies (e.g., neuromuscular disorders, fetal akinesia • syndrome) • Duration of fetal movements Uterine • Placental location • Amniotic fluid volume Mrs. Mahdia Samaha Kony

5. A popular approach is to have the patient lie on her left side and count distinct fetal movements. • Counting 10 movements in a period of up to 2h is felt to be reassuring. • If the count is nonreassuring or decreased, further assessment is recommended (such as NST with AFV assessment or BPP), and the physician should be contacted immediately. • The relationship between decreased fetal activity and poor perinataloutcome has been well established Mrs. Mahdia Samaha Kony

6. Dangers of decrease fetal movement • 35% risk of Stillbirths • Poor neonatal condition at birth : • Abnormal labor FHR patterns • Cesarean for fetal distress • 5-min Apgar scores ≤ 6. • Fetal growth restriction was almost 10 times higher than that of the active group Mrs. Mahdia Samaha Kony

7. Contraction stress test (CST) • Designed to detect uteroplacental insufficiency before fetal compromise, this test is based on the response of the FHR to uterine contractions. • It relies on the premise that fetal oxygenation will be transiently worsened by contractions. • In the suboptimallyoxygenated fetus, the resultant intermittent worsening in oxygenation will, in turn, lead to the FHR pattern of late decelerations. Mrs. Mahdia Samaha Kony

8. Lying in a lateral recumbent position, the patient has an external fetal monitor record both the FHR and uterine contractions simultaneously for a 20- to 30-min interval. • If the patient is spontaneously contracting, and the frequency is ≥ 3 contractions/10 min, and the duration of each contraction is ≥ 45s, then uterine stimulation is not required Mrs. Mahdia Samaha Kony

9. If these criteria are not met: • nipple stimulation • exogenous oxytocin can be used . • Once adequate contractions are achieved, the oxytocin infusion is discontinued. The CST should be avoided when there is a contraindication to labor: • prior myomectomy • classical Cesarean section scar • placenta previa or placental abruption, • Premature rupture of membranes (PROM), • Current preterm labor • Multiple gestations • Incompetent cervix. Mrs. Mahdia Samaha Kony

10. The most common result is a negative CST, which indicates adequate fetal oxygenation in the presence of contractions. • It has also been consistently associated with a good fetal outcome. • One group reviewed data from their institution along with the literature, and found that the incidence of antepartum fetal death (within 1 week of a negative CST) was 0.2–0.7%.11 • The literature suggests that there is a low incidence (<1%) of antepartum fetal death within 1 week of testing. • In general, a positive CST implies uteroplacental insufficiency and has been associated with adverse perinatal outcome and an increased incidence of intrauterine demise Mrs. Mahdia Samaha Kony

11. Mrs. Mahdia Samaha Kony

12. Nonstress test (NST) • This testing modality is based on the premise that the heart rate of the fetus that is not acidemic or neurologically depressed will temporarily accelerate with fetal movement. • FHR reactivity is felt to be a good indicator of normal fetal autonomic function and well-being; it depends on normal neurological development and normal integration of the central nervous system (CNS) control of FHR. • The purpose of the NST is to identify both normal fetuses and those with asphyxia/hypoxia. • NST (compared with the CST) has the advantages of time, easier interpretability, and lack of contraindications. Mrs. Mahdia Samaha Kony

13. Reactive trace • The tracing is categorized as reactive (normal) or nonreactive. • The most common definition is ≥ 2 FHR accelerations [which peak, but do not necessarily remain, at least 15 beats per minute (b.p.m.) in amplitude above the baseline, and last 15 s from baseline to baseline] within a 10- or 20-min period, with or without fetal movement Mrs. Mahdia Samaha Kony

14. Nonreactive trace Causes: • Most commonly associated with a sleep cycle • CNS depression (including). • Fetal acidemia; Fetal hypoxia, asphyxia • Gestational age • Drugs: depressants (narcotics, phenobarbital), betablockers (propranolol) • Smoking Mrs. Mahdia Samaha Kony

15. Routine NST interpretation does not take gestational age into account; however, this is an important consideration, as preterm fetuses are less likely to have FHR accelerations in association with fetal movements. • In summary, while a reactive NST is usually associated with good outcomes, most fetuses who do not show accelerations during an NST are also not compromised. Mrs. Mahdia Samaha Kony

16. Vibroacoustic stimulation (VAS) • This method may elicit FHR accelerations by utilizing an artificial larynx (positioned on the maternal abdomen over the fetal vertex) with a stimulus of 1–2 s being applied. • This may be repeated up to three times (at 1-min intervals) for progressively longer durations (of up to 3 s) to elicit accelerations. • The normal fetal response to VAS includes not only FHR accelerations, but also increases in long-term FHR variability and gross body movements. Mrs. Mahdia Samaha Kony

17. Consequences of nonreactive after VAS • Increased rates of intrapartum fetal distress • Fetal growth restriction • Low Apgar scores • Gestational age appears to affect the FHR response to VAS, with a maturational response as gestation advances Mrs. Mahdia Samaha Kony

18. Biophysical profile (BPP) • The BPP is performed using real-time ultrasonography to assess multiple fetal biophysical activities, as well as AFV. • The observation is continued until either normal activity is seen or 30 consecutive minutes of scanning have elapsed. • The BPP is unique in that it assesses both acute (FHR reactivity, fetal breathing movements, fetal movements, fetal tone) and chronic markers (AFV) of fetal condition. • The fetus will respond to central hypoxemia/acidemia by altering its movement, tone, breathing, and heart rate pattern. Mrs. Mahdia Samaha Kony

19. Mrs. Mahdia Samaha Kony

20. Amniotic fluid volume (AFV) assessment • Amniotic fluid (AF) is essential to pregnancy, providing a compartment for normal development, growth, and movement of the fetus. • AFV is a chronic marker of fetal well-being, and a normal AFV also protects the fetus from cord compression during fetal activity or uterine contractions. • This volume changes during pregnancy ; at 22 weeks, the average AFV is 630 mL, and this increases to 770 mL at 28 weeks. • Between 29 and 37 weeks, there is little change in volume, which averages 800mL. • Beyond 39 weeks, AFV decreases sharply (averaging 515mL at 41 weeks). Once a patient becomes postdate, there is a 33% decline in AFV per week, consistent with clinical observations of an increased incidence of oligohydramnios in post-term gestations Mrs. Mahdia Samaha Kony

21. Mrs. Mahdia Samaha Kony

22. In the second half of pregnancy, the main sources of AF include fetal urine excretion (especially) and fluid secreted by the fetal lung. • Fetal urine production rates appear to be in the range of nearly 1 L/day near term. • The primary pathways for fluid removal are fetal swallowing (mainly) and intramembranous absorption into fetal blood perfusing the fetal surface of the placenta. Mrs. Mahdia Samaha Kony

23. The uterus “divided” into four quadrants (linea nigra and umbilicus divide the uterus into right/left halves and upper/lower halves respectively), the vertical diameter of the largest pocket in each quadrant (umbilical cord free) is measured. • The summation of all four quadrant numbers equals the AFI (in cm) (Fig. 32.5). In low-risk pregnancies, the mean AFI was 16.2 + 5.3 cm Mrs. Mahdia Samaha Kony

24. Mrs. Mahdia Samaha Kony

25. Polyhydramnios • Polyhydramnios (pathologic accumulation of AF), which is defined as an AFI > 25cm, occurs in 0.2–1.6% of the general population. • It is associated with increased maternal and perinatal morbidity and mortality . • The causes of polyhydramnios depend on its severity. Mrs. Mahdia Samaha Kony

26. Causes of polyhydramnios • Fetal malformations; gastroschisis, duodenal atresia • anencephaly • Genetic disorders • Diabetes • Rhesus (Rh) sensitization • Congenital infections. • Fetal swallowing impairment Mrs. Mahdia Samaha Kony

27. Potential complications associated with polyhydramnios. • Premature labor • Placental abruption • Puerperal hemorrhage • Perinatal mortality • Maternal respiratory difficulties Mrs. Mahdia Samaha Kony

28. Oligohydramnios • Oligohydramnios (reduced AFV) occurs in 5.5–37.8% of pregnancies, and is significant because of its known association with adverse pregnancy outcome: • umbilical cord occlusion • Fetal distress in labor • Meconium aspiration • Operative deliveries • Stillbirth . Mrs. Mahdia Samaha Kony

29. Causes • Intrauterine growth restriction • Urinary tract malformations • Postdate pregnancies • Ruptured membranes. • Placental insufficiency. Mrs. Mahdia Samaha Kony

30. Potential consequences of oligohydramnios • Umbilical cord compression • Meconium-stained amniotic fluid • Fetal demise • Deformation syndrome • Pulmonary hypoplasia • Maternal or neonatal infection Mrs. Mahdia Samaha Kony

31. Alpha-Fetoprotein Testing • Alpha-fetoprotein (AFP) is a protein synthesized first by the yolk sac and then primarily by the fetal liver. The fetal AFP level increases until about 20 weeks and then declines to term. • The normal AFP levels in maternal serum continue to rise until around 32 weeks. • Alterations in AFP levels in either amniotic fluid or maternal serum have multiple possible etiologies. • In general, an increase in maternal serum AFP is due to “leaking” of fetal AFP through an opening in the fetal skin—that is, an open neural tube defect or an open ventral wall defect. Mrs. Mahdia Samaha Kony

32. Mrs. Mahdia Samaha Kony

33. Normative levels of MSAFP are dependent on many factors: • Gestational age • Maternal age • Race • Weight • Diabetes Therefore, careful assessment of gestational age and accurate reporting of maternal factors to the lab play a part in getting accurate screening results. Mrs. Mahdia Samaha Kony

34. The placenta also plays a role in elevated MSAFP levels. • If the placenta is large or malpositioned, more AFP may cross into the maternal circulation • A placental defect may also allow an abnormal amount of fetal AFP to pass from the fetal blood to the maternal serum Mrs. Mahdia Samaha Kony

35. Multiple Marker Screening • Multiple marker screening most commonly consists of: • MSAFP, • hCG, • unconjugatedestriol, Both trisomy 21 (Down syndrome) and Edwards syndrome (trisomy 18) have increased detection rates with multiple marker screening. In trisomy 21, hCG levels are high, while estriol and AFP levels are relatively decreased. In trisomy 18, all three values are low. These tests are well demonstrated to increase the detection rates of chromosomal abnormalities, identifying about 60 percent of fetuses with trisomies 21 or 18. Mrs. Mahdia Samaha Kony