Abstract
What is the goal of perinatal care?
Acknowledgments The author would like to thank Dr. Büşra Aynalı who contributed to this chapter.
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What is the goal of perinatal care?
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The care of women and fetus or newborn given; before, during, and after delivery; from the 28th week of gestation through the seventh day after delivery
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Fetal health
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Recognizing diseases and intrauterine treatment
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First trimester fetal life, detecting major anomalies
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Second trimester congenital anomalies, syndromes, toxic effects
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Third trimester fetal well-being
Which methods are being used for perinatal care?
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Non-stress test (NST)
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Contraction stress test (CST)
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Fetal biophysics profile (BPP)
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Amniotic fluid index (AFI)
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Doppler ultrasound
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Counting of fetal movements (kick counting)
Why is perinatal care important?
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Fetal death is seen in 1% of all third trimester low-risk pregnancies without routine perinatal care.
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Two thirds of deaths are intrauterine, and this rate increases especially in high-risk patients.
Which pregnancies are considered as high-risk pregnancies in the aspect of uteroplacental insufficiency?
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Prolonged pregnancy
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Diabetes mellitus (DM)
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Hypertension (HT)
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Isoimmunization
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Stillbirth in previous pregnancies
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Intrauterine growth restriction (IUGR)
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Advanced mother age
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Discordant multiple pregnancy, as in twin-to-twin transfusion syndrome (TTTS)
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Antiphospholipid syndrome (APS)
Describe the role of non-stress test (NST) in perinatal care
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A good test interpreted as reactive. There should be:
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At least two fetal movements
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At the same time two accelerations lasting 15 s and not less than 15 beats/min in 20 min of monitoring for reactivity
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Fetal heart rate: 120–160/min
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In some fetuses, 110–120/min fetal heart beats can also be considered as normal
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May be physiologically non-reactive NST before 30th gestational week
What is the role of the stress test (CST) in evaluating fetal well-being?
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It is the most precious test for the evaluation of fetal well-being.
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Blood flow to intervillous area decreases during uterine contractions.
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Blood supply decreases up to 30%.
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If there is no placental insufficiency, the baby responds to it as acceleration.
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Responds as deceleration if there is insufficiency.
How would you apply contraction stress test (CST)?
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Test is done by creating contractions, three contractions within 10 min.
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Oxytocin is given to form contraction, or nipple stimulation.
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Should be laid semi-Fowler and 30–45° lateral position to avoid supine hypotension.
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The CST is used for its high negative predictive value.
What is the meaning of positive CST?
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Late decelerations present with more than half of the uterine contractions. Generally it shows placental respiratory insufficiency is present.
What is the meaning of negative CST?
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No late deceleration presents with adequate uterine contractions present. Generally marker of fetal well-being.
What are the contraindications of contraction stress test (CST)?
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It should not be done to patients who are at risk of premature birth.
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Premature rupture of membranes (PROM).
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Multiple pregnancy.
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Pregnant with vaginal bleeding.
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Cervical cerclage.
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Preterm labor.
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Placenta previa or ablation placenta.
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Patients who previously had C/S with vertical (classical uterine) incision.
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Previous history of myomectomy.
What are the evaluation criteria of CST?
Comment | Criteria | Incidence (%) |
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Negative | 3 contractions/10 min No deceleration | 80 |
Positive | Deceleration with 50% contraction | 3–5 |
Suspicious | Temporary deceleration | 5 |
Hyperstimulation | More than 5 times deceleration with contraction in 10 min | 5 |
Insufficient | Fewer than three contractions occur within 10 minutes, or quality of tracing is inadequate for accurate interpretation. Repeat test on the following day. | 5 |
What are the parameters of fetal biophysical profile (BPP) evaluation?
Parameter | Normal (2 points) | Abnormal (0 point) |
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NST | Reactive | Non-reactive |
Fetal respiration | Lasting for 30 s at 30 m | No movement or less than 30 s |
Movement | At least three fetal movement | Reduced movements |
Tonus | Extension, flexion Opening and closing of hands | Continuous extension and open fingers |
Amnion fluid | At least 2 cm of pocket in two planes | Less fluid |
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If the score is 10, probability of fetal death in 2 weeks is 0%.
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If the score is 0, probability of fetal death is around 60%.
What are the parameters in the modified fetal biophysical profile (BPP)?
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NST and Amniotic fluid index (AFI) measurements: also indicators for fetal well-being.
What are the features of the amniotic fluid volume?
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200 mL at 16th week.
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1000 mL at the beginning of the third trimester.
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Weekly decreases by 150 mL after 38 weeks.
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Renewed about 95% per day.
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It is directly related to uteroplacental blood flow.
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If uteroplacental blood flow decreases, fetal renal blood flow and fetal renal glomerular filtration rate (GFR) also decreases so oligohydramnios occurs.
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It is the sum of the deepest pockets on the four uterine quadrants.
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Perinatal mortality and morbidity increased in patients with Amniotic fluid index (AFI) below 5 cm.
How would you advise your patient to count fetal movements?
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Fetal movements/kicks indicate fetal well-being.
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Fetal movements may decrease due to the decrease of amnion fluid in the third trimester.
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Fetal movements should be at least 10 per day.
Which vessels are measured by Doppler velocimetry?
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Uterine artery
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Umbilical artery
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Fetal middle cerebral artery (MCA)
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Umbilical vein
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Ductus venosus (DV)
What are the characteristics of Doppler measurement?
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Ultrasound sound waves hit the blood, and moving elements like erythrocytes turn back those waves.
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Frequencies of the outgoing sound waves and returning sound waves are different.
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This is called the Doppler effect, and the frequency change is called the Doppler frequency.
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Blood flow in the ultrasound is measured by measuring the movement of blood flow.
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A sound wave is sent from the transducer to capture blood flow.
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The echoes obtained from the fixed tissues through which the sound wave passes are always the same.
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Echoes obtained from moving tissues such as blood vary according to the return of the signal to the recipient.
Which Doppler indexes are used during pregnancy?
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Systole/diastole (A/B).
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Pulsatility index (S-D/mean).
It is difficult to calculate, but it is the most reliable measurement in very small vessels or vessels without diastole flow. It can be easily calculated.
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Resistance index (S-D/S).
Relationship between fetal circulation and Doppler ultrasound?
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Diastole flow of umbilical artery increases near term.
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High S/D ratio is a very important parameter in IUGR.
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Excessively affected fetuses do not have diastolic flow or have reverse flow.
Explain the importance of Doppler measurement for ductus arteriosus.
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Doppler measurement of Ductus arteriosus should be considered as primary in the use of indomethacin and other nonsteroidal anti-inflammatory drugs, due to the side effect of the prostaglandin inhibitors (PGI) that is early closure of ductus arteriosus. Indomethacin is used for tocolysis and in the treatment of polyhydramnios.
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Indomethacin causes constriction at ductus arteriosus, to increase in pulmonary flow and reactive pulmonary arteriolar hypertrophy; pulmonary hypertension.
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If the medication is discontinued before 32nd week, this condition is resolved.
In which case is Doppler measurement of the mid cerebral artery (MCA) used?
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Peak systolic velocity (PSV) increases (>1.5 MoM) in case of fetal anemia—due to increased cardiac output and decreased blood viscosity.
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MCA/placental blood flow rate may be used depending on the brain protective effect in the presence of fetal hypoxemia.
In which situations uterine artery Doppler measurement is used?
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In normal pregnancy, uterine blood flow increases from 50 mL/min to 500–700 mL/min.
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Uterine blood flow is characterized by high diastolic blood flow.
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Increased resistance and presence of diastolic notch indicate hypertension.
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Pregnancies that will develop HT or preeclampsia may be predicted in Doppler measurements performed at 16–20th gestational ages.
What is the most valuable test for evaluating fetal well-being?
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CST
What is the mechanism of late deceleration in NST or CST?
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In fetuses with reduced oxygen reserve, periodic decreases in oxygen during contractions reach the critical level, which trigger the carotid chemoreceptors. As a reflex, an alpha sympathetic response that constricts the low-resistance arterial bed is initiated. This results in a systemic arterial hypertension that causes the baroreceptors to produce a vagal response that slows down the fetal heart rate and is seen as a late deceleration.
Suggested Reading
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Sel, G. (2020). Perinatal Care. In: Practical Guide to Oral Exams in Obstetrics and Gynecology . Springer, Cham. https://doi.org/10.1007/978-3-030-29669-8_6
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