Assessment of fetal wellbeing

1. Assessment of fetal wellbeing By Dr. Khattab KAEO Prof. of Obstetrics and Gynaecology Faculty of Medicine, Al-Azhar University, Damietta

2. Indications for fetal wellbeing surveillance

3. Many cases of medical disorders. • Prolonged pregnancy: >10 days after the EDD or earlier in older mothers. • Reduced fetal movements.

4. Cardiff count-to-ten: The patient begins to count movements at 8 AM daily and marks the 1/2 h at which the 10th movement is felt. If 10 movements are not felt by 8 PM or if it takes twice to feel 10 movements as on prior days, the physician is noted. In another opinion, notification is indicated if there is no movement for 1 day or if <10 movements are felt on 2 days. Cases with reduced fetal movements are referred for CTG tracing.

5. Symphysis-fundal height (SFH): Using a non-stretchable tape, the fundal height is measured from the upper border of the symphysis pubis. From the 24th week of gestation this measurement follows "the rule of thumb" i.e. the fundal height in centimetres (cm) corresponds to gestational age in weeks. In a normally-progressing pregnancy SFH measures 30 cm at 30 weeks, 34 cm at 34 weeks....

6. Biophysical profile (BPP):Constituents: -3 gross FMs in 30 min. Simultaneous limb and trunk movements are counted as a single movement. - Fetal tone is exemplified by prompt return to flexion after extension of the limbs or trunk. Other examples include arching, kicking and opening and closing of the hands. -Continuous breathing movements (movement of chest & abdominal wall) for 30 seconds at least once in 30 min.

7. Principles: - If the normal NST findings are not obtained within 20 min, test time is extended to 40 min. - Due to fetal cycles of activity-inactivity (20-40 min), it is advisable to have a meal 1-2 hours before testing. - Frequency of testing depends on the clinical situation and varies from daily to weekly testing. - BPP is useful from 28 weeks onwards. The earliest we begin testing is at 26 weeks. - The principle is that different sites in the fetal brain control different biophysical events. FMs, fetal tone, FBMs & CTG are markers of acute fetal asphyxia, while amniotic fluid volume is a marker of chronic hypoxia. - The first marks to go in case of fetal hypoxia are breathing and FHR reactivity, and the last to go are movements and tone.

8. Interpretation: Each parameter scores either 2 or 0. - With a score of 8-10 intervention is not indicated, un less for clinical reasons & the test is repeated weekly - A score of 6 is equivocal. Intervention is advised if the fetus is mature; if not, re-test within 24 h. - With a score of <6 the relative risk of fetal or NN death is increased by 6-x. A score of <6 could be reassuring provided there is no oligohydramnios. - A score of 4 is associated with a PNMR of 90/1000. - A score of <4 in a mature fetus is an indication of immediate delivery. If the fetus is immature, this constitutes a real dilemma. The decision could be immediate delivery, delivery preceded by steroid-induced lung maturation, or further fetal assessment by prolonged NST or CST depending on the clinical situation and the degree of fetal immaturity.

9. - The incidence of false -ve rate = 0.8/1000 i.e. the test has a high predictive value –within a week- for good perinatal outcome when the result is normal. In contrary, the false +ve rate for abnormal NST or abnormal FBMs is >80% for poor perinatal outcome and >95% for PND. BPP is affected by factors which suppress the CNS such as hypoxia, infection & medication. - With an abnormal score, the possibility of neurological dysfunction should be considered. - The test is time-consuming and provides little additional information. It has now been super-seded by CTG&amniotic fluid vol (modified BPP) and growth assessment. - In modern evidence-based obstetrics BPP has been classified as care of unknown effectiveness

10. Cardiotocography (CTG) Scaling is recommended at 3 cm/min paper speed. Definitions:Baseline FHR: 110-150 bpm according to the FIGO classification. It is the modal characteristics that prevail apart from periodic accelerations or de-celerations. It decreases 24 bpm between 16 weeks and term (1bpm/w) due to maturation of vagal tone Rate is rounded to increments of 5 bpm during a 10-min segment. The minimum interpretable baseline duration must be 2 min. Long-term variability is oscillatory changes that occur over 1 min; 5-25 bpm. It may be reduced for up to 30 min (or even absent) due to fetal sleep or drugs (diazepam). However, the most important cause is fetal hypoxia. Variability is regulated by the sinoaortal node. Short-term variability is taken from 1 beat [or R wave] to the next, so it is most reliably deter-mined with a scalp electrode. Reduced variability is the most reliable sign of fetal compromise.

12. Bradycardia: <100 bpm for >3 min (according to FIGO; <110 bpm according to ACOG). It could be due to drugs (like -blockers) or congenital fetal heart block. However, it could be due to fetal distress.

14. Tachycardia: >150 bpm (according to FIGO; >160 bpm according to ACOG). It could be idiopathic, or due to drugs (like atropine & mimetics), fever, maternal or fetal hyperthyroid., maternal or fetal anaemia or prematurity. However, it could be due to fetal distress. • Sinusoidal pattern: Type I (saw tooth) with almost fixed variability. It is benign Type II with smooth sine wave & a regular frequency of <6 cycles/min and an amplitude of >10 bpm. It is pre-terminal. It is seen with serious fetal anemia of D-iso-immunisation, ruptured vasa previa & twin-to-twin transfusion. Differential diagnosis is effect of drugs like morphine, alphaprodine and butorphanol

15. Deceleration Gradual fall in FHR by ≥15 bpm for ≥15 sec. It is stimulated by chemoreceptors. Early deceleration: The nadir occurs ≤20 sec of the peak of contraction; now: 30 sec after the onset of contraction). The waveform is symmetrical. Early deceleration is the result of head compression during uterine contrac. which probably causes vagal nerve activation. It is not associated with hypoxia, acidemia or low Apgar scores.

16. This early deceleration is deemed benign because some contractions are not associatedwith decelera tion, and shoulders (particularly pre-deceleration ones) are not lost. Finally, other items like baseline FHR and variability are normal. The most right drop in FHR (white arrow) is not regarded as decelera-tion because the drop is <15 bpm.

18. Early decelerations are not always benign. It is deemed sinister in the following conditions: 1- If associated with one of thefollowing: FHR <100 bpm  ineffective placental perf Rising FHR. Loss of long-term variability. Loss of shouldering. 2- If unprovoked i.e. without active uterine contractions. 3- If it is repetitive or deep.

19. Late deceleration The waveform of FHR decrease shows gradual onset and recovery and is symmetrical. Onset begins at or after the peak of contraction. The nadir occurs >20 sec after the peak of contraction (now: 30 sec). Return to the baseline only occurs after the contraction has ended. This diagnosis is applicable only for 3 such decelerations following consecutivecontractions So, it can occur occasionally (reassuring signs are: the presence of shouldering & variability, in addition to normal baseline). Typically, depth is no >10-20 bpm (i.e. shallow). It is attributable to reduced placental blood flow with deep ones are seen with abruption. It more commonly occurs with maternal hypotension and excessive uterine activity. It is deemed sinister if deep (FHR decreases by>60 bpm) and prolonged (persists for >60 sec). Early and late decelerations almost reflect the shape of uterine contraction and all dips are of almost identical shape.

21. Variable decelerations All decelerations that are not early or late. These are the most common decelerations. Dips are of variable shape, depth and correlation to uterine contractions. Onset is abrupt and nadir follows after a <30 sec period. Duration is <2 min. Variable de-celeration is attributable to compression of the umbilical cord. It indicates fetal distress if deep (<70bpm[signif variable deceleration) and persistent (lasting for 60 sec with each contraction) or associated with reduced variability or meconium-stained liquor.

23. Accelerations These are abrupt increase in FHR (>15 bpm) in response to fetal movement, uterine contractions, cord occlusion or fetal acoustic stimulation, stimulation during pelvic examination or scalp blood sampling. During labour they are nearly always associated with fetal movement. They are always reassuring and almost always confirm absence of acidemia.

24. FIGO definition of antenatal CTG Normal: baseline of 110-150 bpm, variability of 5-25 bpm, ≥2 accelerations in 20 min and absence of deceleration except for mild ones of very short duration.

26. Suspicious: baseline 100-110 or 150-170 bpm, variability of 5-10 bpm for >40 min or >25 bpm, no accelerations for >40 min and sporadic deceleration of any type unless severe. • Pathological: baseline of <100 or >170 bpm, variability of <5 bpm, recurring and repeated decelerations of any type.

28. Limitations of CTG use • The major limitation of CTG is that fetaladaptation results in maintenance of the FHR until death. An acute reduction in O2 delivery produces a transient bradycardia. However, if reduction in O2 delivery is prolonged, the FHR returns to normal (a possible effect of catechol.), but with a further acute reduction in O2 delivery there will be lack of response (no reaction). In progressing utero-placental insufficiency there would be: loss of acceleration  deceleration  progressive reduction in variability. The rate usually remains normal. • Also, fetal quiescence is normally associated with loss of acceleration and low variability. A non-reactive CTG with variability present should be continued (up to 2 h) until fetal activity occurs or until its continued absence indicates a problem. • FHR tracing 15% false +ve rate & 0.3% false -ve rate In another opinion 40% of abnormal CTGs occurs in the absence of fetal hypoxia; CS rate will be trebled if CTGs are used alone. Even with the most severely abnormal CTG, the fetus will be hypoxic in only half the cases. • Normal CTG is insufficiently reassuring in at-risk cases.

29. Non-stress test (NST) • The test correlates FHR response to fetal movements. If no fetal movement felt within 20 min, the test is extended for 20 min more, perhaps after acoustic stimulation. • The woman is put in the semi-Fowler position with a lateral tilt. • Two accelerations (↑ in FHR by >15 bpm for >15 sec) within 20 min = "reactive". If this is not achieved within 20 min, the test is deemed "non-reactive". The incidence of false positive rate = 3/1000. The incidence of false negative rate = 3/1000. • Absence of acceleration may indicate hypoxia. • Deceleration with Braxton-Hicks contractions (unstress test) indicates oxygen insufficiency and requires urgent investigation.

30. Contraction stress test (CST) • The test time is 90 min. • Uterine contractions are induced and maintained at a rate of 3/10 min. • The test is deemed "positive" if there are persistent late decelerations with >50% of the contractions. "equivocal" if late de-celerations are occasional. "negative" if there is no late deceleration. • The incidence of false negative rate =1/1000 • If negative, the test is repeated weekly. If positive, a complete BPP is recommended. • The test is contraindicated if there is a previous uterine scar or threatened preterm labour.

31. Thank you