39-assessment Of Fetal Well Being

ASSESSMENT OF FETAL WELL BEING Assessment of fetal wellbeing is either: 

Antepartum: assessment late in pregnancy, before onset of labor.



Intrapartum: assessment during labor.

ANTEPARTUM ASSESSMENT OF FETAL WELL- BEING AIM:

AIM: To detect fetuses at risk of hypoxia during 3rd trimester of pregnancy, so that it can be delivered before IUFD, or hypoxic injury. Fetal hypoxia is mostly caused by uteroplacental insufficiency.

PLACENTAL INSUFFICIENCY

DEFINTION

Failure of the placental functions to deliver adequate oxygenation and nutrition to the fetus.

TYPES 



Acute: Suddenly occurring associated with otherwise normal fetus. (E.g. Placental separation). Chronic: Associated usually with intrauterine growth restriction (IUGR - small for date fetus).

:AETIOLOGY Impairment of the placental circulation due to thrombosis of the vessels or placental infarcts.  Hypertensive states of pregnancy (PE, eclampsia, and chronic hypertension).  Accidental hemorrhage or placenta praevia.  Postmaturity syndrome.  Diabetic pregnancy when associated with vasculopathy.  Placental infarctions.  Idiopathic.

PATHOLOGY Fetal response to placental insufficiency:  Redistribution of blood flow preferentially to the brain and fetal heart.  Asymmetric IUGR.  Oligohydramnios due to reduced renal perfusion.  Decreased fetal movement to conserve energy.  Disturbance of fetal heart rate due to defective autonomic regulation.

DIAGNOSIS OF PLACENTAL :INSUFFICIENCY HISTORY:  Careful history taking may reveal the cause of placental insufficiency, e.g. PE, post maturity, etc. CLINICAL SIGNS suggestive of SGA fetus or Oligohydramnios:  

Poor maternal weight gain during regular ANC follow up (normal = 0.5 kg/wk > 20 wks). fundal level < Gestational age "GA".

ANTEPARTUM FETAL SURVEILLANCE AFS (Placental Function Tests)

Placental Function Tests 

Daily fetal movement count (DFMC).



Non-Stress Test (NST).



Fetal Biophysical Profile (BPP).



Doppler color flow studies.



Oxytocin challenge test (OCT).

( The Non Stress Test(NST Idea: To test FHR changes in response to fetal movements. Procedure: external cardiotocography (CTG) 



Basal FHR is recorded and its changes in response to fetal movements are detected. Duration of the test: FHR recordings over 20 min observation period. The test may be extended for another 20 minutes if fetal movements are insufficient.

:Response to NST Reactive: Normally a rise in FHR of at least 15 bpm, for at least 15 sec. will occur at least twice within a period of 15-20 min. testing. Non reactive: No FHR changes or changes less than normal

Management according to :NST  







Reactive NST: repeat every week. Non reactive NST: Further fetal evaluation: Ultrasound Biophysical Profile Score (BPPS) Colour Doppler velocimetry studies (fetal umbilical and cerebral arteries) Oxytocin Challenge Test (OCT).

Ultrasound Biophysical :(Profile Score (BPPS 

The BPP is one of the most popular and informative tests for antepartum fetal surveillance (AFS). It is a simple test based on clear ultrasound parameters that can pick up those fetuses at risk of hypoxia. Each tested parameter is given a score (either 0 or 2).



Timing of BPP: The test is done any time during the third trimester and can be repeated freely whenever AFS is indicated.

Parameters studied: observation of the following parameters over a period of 30 minutes:     

Fetal tone (flexion attitude of fetal limbs, head and body). Fetal body movements (flexion / extension limb and body movements). Fetal breathing movements (expansion movements of the fetal abdomen). Amniotic fluid volume (or amniotic fluid index - AFI). NST ( normal when FHR accelerations show rise of 15 bpm, for 15 secs, twice in 15-20 min. duration.

Interpretation of the test Each item is scored either 0 or 2, with a maximum 10/10.

Scores of 10 to 10 denote a normal fetal well being, with normal fetal PH.  Scores of 8/10 may need repeating the test and /or adding Doppler US evaluation.  Scores < 8 suggest severe hypoxia. Termination of pregnancy should be considered. 



Scores < 6 denote severe fetal acidaemia, with severely compromised fetal outcome.

Modified BPP 

It combines non - stress test (NST) and Amniotic fluid index (AFI).



It is less complicated and less time consuming.



If the non – stress test is nonreactive, a complete BPP should be done.

COLOR DOPPLER STUDIES OF FETAL BLOOD FLOW 

Measurement of the resistance to fetal blood flow within the umbilical artery and the middle cerebral artery yields excellent information about the state of fetal organ perfusion.



HIGH resistance in the umbilical artery is concomitant with placental insufficiency, while LOW resistance in the fetal middle cerebral artery points to vascular shift and brain sparing, suggestive of hypoxia.



Absent or reversed end-diastolic flow in the umbilical arteries Doppler velocimetry flow studies denotes a severely compromised fetus that needs urgent delivery.

OXYTOCIN CHALLENGE .:(TEST (OCT 

Monitoring FHR changes on CTG, in response to I.V. oxytocin induced mild uterine contractions.  



Positive OCT: FHR decelerations obtained after each uterine contraction (fetal distress). Negative OCT: No FHR changes occur in response to contractions (good fetal well being).

The test has formerly been indicated if the NST was non reactive, however OCT is rarely used nowadays being outdated by the safer and easier Doppler US velocimetry studies.

MANAGEMENT OF PLACENTAL INSUFFICIENCY 



Cases suffering chronic placental insufficiency with IUGR are carefully monitored and delivered nearest to 37 weeks gestation. If Doppler studies revealed very high umbilical artery resistance index with poor BPP score, immediate termination of pregnancy is indicated. Cases with acute placental insufficiency from the start, or those who developed acute on top of chronic insufficiency, with Oligohydramnios, poor BPP scores, abnormal Doppler studies, are for immediate termination of pregnancy

Delivery by CS 

offers the best chance for fetal survival in cases with placental insufficiency when pregnancy termination is indicated. In some selected cases induction of labour may be chosen with continuous electronic FHR monitoring by the CTG. If fetal bradycardia occurs, or if ROM revealed presence of meconium, vaginal delivery is

KEY POINTS IN ANTEPARTUM FETAL :)SURVEILLANCE )AFS

   



  

AFS detects fetuses at risk secondary to utero-placental insufficiency, but cannot predict sudden events. All pregnant women at high risk for placental insufficiency should do a DFMC. The NST should be offered to cases with decreased DFMC or to high risk cases in general. The BPP includes a NST with evaluation of specific US parameters. It should be performed and repeated whenever fetal compromise is suspected. Doppler umbilical artery studies are indicated whenever an abnormal BPP is encountered. Abnormal findings reflect serious fetal condition. Normal AFS tests may be repeated on weekly or biweekly intervals. Abnormal AFS tests necessitate termination of pregnancy. In most cases CS delivery will offer best chances for fetal neonatal survival.

INTRAPARTUM ASSESSMENT OF FETAL WELL BEING 

Aim: To detect fetuses at risk for hypoxia during labour )fetal distress), thus minimizing the risks of intrapartum and neonatal fetal death, or severe fetal hypoxic injury (e.g.; cerebral palsy).



Pathophysiology of hypoxia: Decreased Oxygen supply to the fetus during labour is associated with decreased elimination of CO2, with resultant fetal respiratory acidosis and decreased fetal blood PH.

CAUSES OF INTRAUTERINE FETAL HYPOXIA (FETAL (DISTRESS 1. Acute fetal hypoxia:    

Cord accidents (cord prolapse, cord compression, true knots, coils around fetal neck, and rupture vasa praevia). Placental separation (accidental Haemorrhage, placenta praevia). Placental compression (prolonged ROM, uterine hypertonicity, obstructed labour). Some congenital and or chromosomal fetal anomalies.

2. Chronic fetal hypoxia:  Placental insufficiency.  Maternal hypoxia: (Severe anemia or excessive haemorrhage, congestive heart failure, severe pulmonary disease, during eclamptic fits, during anaesthesia with improper oxygenation).

Diagnosis of Fetal Distress :during Labor A- CLINICAL DIAGNOSIS:  Abnormal FHR recordings by the sonicaid (severe bradycardia, severe tachycardia).  Passage of meconium after ROM in (cephalic presentation not breech). N.B.: Intrauterine asphyxia results in relaxation of the fetal anal sphincter & increased intestinal peristalsis. Meconium, (the thick intestinal particulate secretion in the neonate), will then escape into the amniotic fluid giving it yellowish or greenish colour that appears after rupture of membranes. B- INTRAPARTUM FETAL SURVEILLANCE tests: - IFS  The aim of IFS tests is to detect fetal distress occurring during labour. The best available method for such IFS is the use of continuous external electronic FHR monitoring.

ELECTRONIC FHR MONITORING: ( Cardiotocography – (CTG



The CTG entails Continuous electronic FHR monitoring during labour in relation to uterine activity. An external US transducer is placed on the maternal abdomen at a site selected to give the best FHR recordings. Another transducer is placed to record the onset, duration and intensity of uterine contractions and associated increased intrauterine pressure

Interpretation of FHR Monitoring :by CTG  

Normal FHR tracings: Normal FHR values: 120-140 beat per minute (b/m). Normal FHR Pattern: beat to beat variability (fluctuations by ± 5 to 10 b/m. periodically).

Interpretation of FHR :(.Monitoring by CTG (cont Abnormal FHR tracings:    



Baseline bradycardia: < 100 b/m. Baseline tachycardia: > 160 b/m. Absence of beat to beat variability: FHR variation within 1 min is < 5 b/m. Late Decelerations: Slowing of FHR at the peak of the uterine contraction that returns to normal a short period after the contraction ends. Late deceleration is the most dangerous pattern, as it indicates severe utero-placental insufficiency. Variable Decelerations: Slowing of FHR which is not related to uterine contractions. It mostly indicates cord compression especially in cases with ROM or Oligohydramnios.

N.B.: Early Decelerations refer to slowing of FHR that starts at the onset of the uterine contraction and returns to normal with its end. It is mostly associated with head compression within the bony pelvis with reflex stimulation of vagus nerve. Early decelerations are usually harmless. N.B.: Sinusoidal FHR pattern is a smooth wave like pattern of regular frequency (35 cycles/min), and amplitude (5-20 bpm). Short episodes of sinusoidal FHR patterns are considered a variant of normal. Longer episodes may reflect fetal anaemia and severe hypoxia (e.g. accidental haemorrhage).

Fetal Blood sampling During labour 

Abnormal FHR patterns on CTG during labour are sometimes misleading, with a resultant increase in the rate of unnecessary CS deliveries. In cases where FHR tracings on the CTG are abnormal, fetal blood sampling (FBS) will be the most accurate .



The blood sample is taken via a small needle probe applied to fetal scalp after ROM , which is known as fetal scalp PH. Normal fetal pH ranges from 7.25 - 7.35.



In cases of fetal hypoxia: Accumulation of Co2. (Anaerobic pathway for energy & lactic acid).



This leads to fetal acidosis. If < 7.25 =Mild acidosis.

Management of fetal distress :during labour 



High risk cases should be offered a continuous CTG monitoring throughout labour. Whenever abnormal CTG findings are recorded  Stop oxytocin, if it has been infused  Change position of the mother to Left lateral position .  O2 mask to the mother )to avoid maternal hypoxia).  I.V. Fluids )to avoid maternal dehydration).

If the above measures are successful): Labour is allowed to proceed under strict observation.

Management of fetal distress during labour :(.(cont

If The above measures were unsuccessful i.e.;  FHR patterns showed persistent abnormality.  Abnormal FHR patterns recurred after a period of normality.  A difficult and prolonged vaginal delivery is anticipated. An immediate delivery by CS will be the best and safest option available.

N.B.: If fetal distress occurs when the cervix is fully dilated, the membranes ruptured, the presenting part engaged, and the maternal pelvis is adequate, immediate vaginal delivery may be encouraged by:  Instrumental delivery by the low forceps procedure.  Breech extraction in cases of complete or frank breech presentations.

Key points in intrapartum :)fetal surveillance )IFS 

Cases at high risk for fetal hypoxia should be selected and carefully monitored throughout labour.



Intrapartum fetal monitoring will detect early fetal hypoxia.



IFS, has decreased the number of intrapartum fetal deaths, but it has increased the number of CS deliveries.



FHR accelerations signify normal fetal PH and intact CNS.

Key points in intrapartum :).fetal surveillance )cont 

Decelerations are characterized based on the timing with contractions:

•

Early decelerations: head compression vagal response (no hazards). Late decelerations: uteroplacental insufficiency (serious hypoxia anticipated). Variable decelerations: cord compression (especially with ROM or oligohydramnios).

• •

Whenever IFS points to fetal distress, measures should be taken for immediate delivery: Most cases will benefit from immediate CS. Some selected cases may continue a carefully monitored trial for a rapid vaginal delivery.