ANTEPARTUAL EVALUATION
Fetal Movements
• Perception of fetal movements is an indicator of fetal well-being. If 10 or more significant movements are felt within 2 hours after the 28th week of pregnancy, it indicates that the fetus is good.
Fetal Respiration
• Although this measurement is not alone, it is used as a parameter of the biophysical profile.
Non-Stress Test (NST)
• It is a test in which fetal heart beats increase during fetal movement. Since it shows the maturation of the fetal autonomic nervous system, it is also an indication that the fetus is well.
• It is usually applied once a week. However, it should be repeated more frequently in postterm pregnancies, multiple pregnancies, type 1 diabetes, IUGR or hypertensive conditions (2 times a week or more).
Reactive NST (R-NST)
► Defined as at least two periods of acceleration (acceleration) with normal heart rate (120-160 beats), normal variability, lasting at least 15 seconds within 20 minutes, increasing more than 15 beats from baseline, in NSTs performed after 32 weeks of pregnancy .
► Causes of fetal death following a reactive NST include; meconium aspiration (most common), cord pathologies, intrauterine infections and detachment.
Non-reactive NST (NR-NST)
► It is the absence of 2 defined accelerations within 20 minutes of follow-up. The first conditions to be considered in NR-NST are that the fetus is asleep, the mother is hungry, or the mother has used cigarettes or sedatives. After these conditions are corrected, the NST is repeated.
► Poor perinatal outcomes are obtained in only 20% of NR-NST cases at term. Therefore sometimes NST needs to be extended to 90-120 min. If they remain non-reactive despite being prolonged, this is considered an indication that the fetus is very bad. Placental infarction (most common), oligohydramnios, IUGR, fetal acidosis and mel<onium may be responsible for such NR-NST results.
Contractions (Oxytocin) Stress Test (CST - O T)
• Unlike NST, CST is a test that shows uteroplacental reserve. Uterine contraction placenta! It reduces blood flow by about 20-30%. A fetus without uteroplacental perfusion disorders tolerates it.
• The test is administered spontaneously or with nipple stimulation or oxytocin infusion, with at least 3 contractions lasting at least 40 seconds over a 10-minute period.
• The absence of deceleration in more than 50% of the contractions created is reassuring and is called a negative CST. The presence of severe variable or late deceleration as a result of the contractions created is called positive CST and bad perinatal outcomes occur in 35-40% of these traces.
Biophysics Profile (BPP)
• It is a scoring system consisting of 5 different parameters used to determine fetal well-being. The test is usually 30-60 min. takes. There are 5 basic variables in BPP.
|
biophysics
profile |
||
|
PARAMETER |
2 POINTS |
0 POINTS |
|
NST (20-40 min.) |
>2 accelerations (within 20-40 minutes) |
0-1 acceleration |
|
Fetal respiration (30 min.) |
>= 1 breath lasting 30 seconds (within 30
minutes) |
Breathing lasting <30 sec |
|
Fetal movement (30 min.) |
>= 3 body/extremity movements (within 30 min.) |
<3 body/extremity movements |
|
Fetal tone (30-60 min.) |
>= 1 extremity extension-flexion |
0 limb extension flexion |
|
Amniotic fluid amount (AFI) |
At least 2 cm. 2 pockets measured in depth (2x2 cm.
cap) |
< 2 cm. one deep pocket |
|
Evaluation of
the biophysical profile |
||
|
Point |
Comment |
Recommended Treatment |
|
10 |
Normal, nonasphyctic fetus |
NO Intervention , test can be repeated weekly |
|
8/ 10 (AFI normal) 8/8 (no NST) |
Normal, nonasphyctic fetus |
Intervention vok, test can be repeated weekly |
|
8/10 (AFI decreased) |
Suspected chronic fetal asphyxia |
Birth |
|
6 |
Possible fetal asphyxia |
Birth with reduced AFI, >36. week and delivery if
AFl is normal, delivery if < 6 points in test repetition, follow-up if 6
points in repeat test |
|
4 |
Most likely fetal asphyxia |
If the test is repeated on the same day and the
score is < 6, delivery |
|
0---2 |
Definite fetal asphyxia |
Delivered quickly (cesarean section) |
• NST can be neglected if all four ultrasonographic parameters are normal. If the largest vertical amniotic fluid pocket is 52 cm, further investigation is required regardless of the biophysical profile. Fetal tone is the last parameter to deteriorate in fetal asphyxia.
• Recently, modified BPP based on the measurement of amniotic fluid with NST has been applied. Studies have shown that it is at least as sensitive and specific as classical BPP. It has replaced the classical BPP today as it requires less time.
DOPPLER ULTRASONOGRAPHY
• Doppler ultrasonography is a noninvasive method. While Doppier examinations of the umbilical artery, middle cerebral artery (MCA) and ductus venosus provide information about fetal circulation; Uterine artery Doppler examination gives information about placental circulation.
• Umbilical artery Doppler examination can only be used in IUGR cases.
Middle cerebral artery (MCA) Doppler is a noninvasive examination method in the diagnosis of fetal anemia and in the follow-up of treatment. The Doppler parameter that best predicts perinatal outcomes is the ductus venosus Doppler; however, it is meaningless to use it routinely because it occurs too late.
Intrapartum monitoring
Electronic Fetal Monitoring
• It is used for continuous monitoring of fetal heart beats during birth.
bradycardia
► 110 beats/min. of fetal heart rate. that it is under. Bradycardia does not indicate fetal distress if variability is normal and accelerations are also present. However, if the number of beats falls below 80, it creates an unreliable trace.
Some causes of bradycardia:
0 Fetal heart block due to maternal SLE
0 Maternal hypothermia
0 severe pyelonephritis
0 Severe fetal distress
0 Maternal general anesthesia
0 Head compression due to occiput posterior or transverse position in the second stage of labor
0 Maternal hypoglycemia
0 Maternal CMV infection
tachycardia
► Fetal heart rate is 160 beats/min. that it is above. While the prognosis is good in tachycardias without deceleration; The prognosis is poor when there are late or variable decelerations.
Some causes of tachycardia:
0 Maternal hyperthermia due to maternal infections and chorioamnionitis (most common cause)
0 Early stages of fetal hypoxia
0 Fetal anemia
0 Maternal hyperthyroidism
0 Fetal cardiac tachyarrhythmia
0 Drugs used by the pregnant
- Parasympatholytics (atropine, phenothiazine)
- Sympathomimetics (terbutaline, ritodrine)
Variability
► Variability is an important indicator of cardiovascular function and is under the control of the autonomic nervous system. Therefore, parasympathetic and sympathomimetic effects show ups and downs (oscillations) in basal heart rate with opposite movements.
► Loss of variability, especially with decelerations, is an indication of fetal acidemia and this situation is fatal. Metabolic acidemia depresses the fetal brain and heart.
► Some conditions that lead to reduced variability:
0 Maternal acidemia (diabetic ketoacidosis etc.)
0 Analgesics (meperidine, morphine, etc.)
0 CNS depressants (narcotics, barbiturates, phenothiazines, tranquilizers, diazepam, buprenorphine)
0 Butorphanol
0 General anesthesia
0 Epidural analgesia
0 Magnesium sulfate
0 Corticosteroids
0 Anencephaly
0 Fetal anemia
Decreased or lost baseline variability is the most reliable indication that the fetus is in danger.
accelerations
► Periodic, transient increases in fetal heart rate more than 15 beats lasting longer than 15 seconds. They are mostly related to fetal activity and are always reassuring traces that indicate that the fetus is not acidic.
decelerations
► Periodic and transient decreases in fetal heart rate. They are divided into 3 groups as early, variable and late. This classification is made according to their connection with contractions, form and time.
Early Decelerations (head press)
0 They are the reductions in heartbeats that start simultaneously with the contraction and return to the normal basal rate with the end of the contraction.
0 Unrelated to fetal hypoxia, acidemia and low APGAR score.
They develop as a result of vagal reflex due to increased intracranial pressure as a result of compression of the fetal head. Benign is trace, travail is followed by doing nothing
Late decelerations (uterplacental insufficiency)
0 They are the reductions in heartbeats that begin during or after the peak of contractions and continue for a while after the contraction ends and return to the normal basal rate.
► Causes of Late Deceleration:
0 Maternal hypotension: Especially due to epidural analgesia (most common}
0 Uterine hyperstimulation: Due to oxytocin infusion (most common}
0 Hypertensive diseases
0 diabetes
0 Collagen-vascular diseases
0 Ablation placenta (detachment)
Variable Decelerations (cord compression)
0 Structure and initial variable, not necessarily repetitive, not related to contractions.
0 Variable decelerations 70 beats/min. If it lasts for at least 60 seconds or more, it indicates that the fetus is in absolute danger.
Variable decelerations are traces that occur only as a result of cord compression.
Sinusoidal Trace
► True sinusoidal trace is indicative of severe fetal anemia (E-OOJ.
► Conditions leading to sinusoidal trace:
0 Rh isoimmunization
0 Vasa previa bleeding
0 Feto-maternal hemorrhage
0 Twin-to-twin transfusion syndrome
0 Fetal intracranial hemorrhage
0 Parvovirus infection
0 Severe fetal asphyxia (hypoxia)
0 Chorioamnionitis
0 Fetal distress
0 Umbilical cord compression
0 Using meperidine, morphine, alphaprodine and butorphanol
Fetal cardiac arrhythmias
► The most common fetal arrhythmia is atrial extrasystole (68%) and usually resolves after delivery.
► If tachyarrhythmias (supraventricular tachycardia, atrial flutter) cannot be treated, antiarrhythmic treatment should be given as they may cause cardiac decompensation and hydrops. Digoxin is the first choice and most commonly used antiarrhythmic in treatment.
Fetal heartbeat patterns are examined in 3 categories.
► Category I: These traces are normal. Indicates a normal fetal acid-base status. There is no need to do anything specific.
0 Basal rate: 110-160 beats/min (bpm)
0 Baseline variability: normal
0 Late or variable decelerations: none
0 Early decelerations: present or absent
0 Accelerations: present or absent
► Category II: Does not predict abnormal fetal acid-base status; however, we do not yet have sufficient evidence to classify them as Category I or III. It requires close observation and constant reassessment.
0 Basal rate:
- Bradycardia without loss of baseline variability
- tachycardia
0 Basal variability:
- Minimal baseline variability
Absence of baseline variability without recurrent deceleration
- Significant baseline variability
0 Accelerations:
- Absence of induced accelerations after fetal stimulation
0 Periodic or episodic decelerations:
- Recurrent variable decelerations with minimal or normal baseline variability
- Prolonged decelerations >2 min, < 10 min
- Recurrent late decelerations with normal baseline variability
- Variable decelerations with atypia features
Category 3: These traces are abnormal. Indicates an abnormal fetal acid-base status. It requires detailed evaluation. Depending on the clinical situation, attempts to correct the abnormal rate heart rate pattern include maternal oxygen supply, changing maternal position, cessation of labor induction, and treatment of maternal hypotension.
0 Loss of baseline variability and any of the following:
- Recurrent late deceleration
- Recurrent variable deceleration
- bradycardia
0 Sinusoidal pattern