Fetal Distres Flashcards
(12 cards)
Fetal distress
Fetal distress is used to express intrauterine fetal jeopardy, as a result of intrauterine fetal hypoxia and clinically
manifested by changes in rate, rhythm and quality of fetal heart rate and biochemical events.
Fetal distress is an ubiquitous term being replaced by Nonreassuring fetal status
It’s a condition that describe inadequate oxygen delivery to fetus during pregnancy or labour resulting in; fetal
hypoxia, abnormal FHR patterns and acidosis
Nonreassuring fetal status is characterized by…
Nonreassuring fetal status is characterized by;
a. Tachycardia or bradycardia
b. Reduced FHR variability
c. Decelerations and absence of accelerations (spontaneous or elicited)
causes of Acute fetal distress
Distress occurs suddenly due to acute events
1) During pregnancy - less common
* Placental separation in placenta previa or abruptio placentae
* Placental insufficiency – IUGR and pre-eclampsia
* Prematurity
* Postmaturity
* Multiple pregnancy
* Maternal diabetes
* Cholestasis of pregnancy
* Maternal pyrexia
* Chorioamnionitis
* Oligohydramnios
* Cord entanglement
* During oxytocin induction
2) During labor- common
* Uterine hyperstimulation following oxytocin for augmentation of labor
* Uterine rupture or scar dehiscence
* Cord prolapse/compression
* Prolonged labour
* Precipitate labour
* Intrapartum placental abruptio
* Injudicious use of analgesics and anesthetic agents
* Maternal hypotension – as in epidural analgesia
causes of chronic fetal distress
Chronic occur slowly usually due to chronic placental insufficiency & IUGR
Chronic placental insufficiency includes: Placenta previa, abruption, circumvallate, infarction and
mosaicism
Maternal condition
Anaemia
Hypertensive diseases in pregnancy
Thrombotic disease
Cardiac disease
Chronic renal disease
Collagen vascular disease
Infections: TORCH agents (toxoplasmosis, rubella, cytomegalovirus and herpes simplex) & malaria.
Multiple pregnancy
Toxins- Alcohol, smoking, cocaine, heroin, drugs
Etiology of Hypoxia, Acidosis, and Fetal Heart Rate Changes
Fetal arterial blood O2 tension is only 25 ± 5 mmHg, while adult values is about 100mmHg.
But fetal O2 consumption, is twice that of an adult per unit weight
And its O2 reserve is only enough to meet metabolic needs for 1 to 2 minutes.
During a contraction uteroplacental blood supply to the fetus is momentarily interrupted
With temporal reduction in blood flow to the placenta, a normal fetus does not develop hypoxia because sufficient
oxygen exchange occurs during intervals between contractions
A fetus whose O2 supply is marginal, is intolerant to stress of contractions & becomes hypoxic.
Under hypoxic conditions, chemoreceptors and baroreceptors in peripheral arterial
circulation of the fetus influence FHR by giving rise to contraction-related or periodic
FHR changes.
Sufficiently severe Hypoxia, also result in anaerobic metabolism, resulting in
accumulation of pyruvic and lactic acid, causing fetal acidosis.
Pathophysiology of fetal distress
Under normal conditions with adequate O2 supply, aerobic glycolysis occurs in fetus & glycogen is converted into
pyruvic acid which is oxidized ultimately via the Kreb’s cycle.
During hypoxia, O2 saturation falls < 40%, anaerobic glycolysis occurs
↓
Lactic acid and pyruvic acid accumulates leading to metabolic acidosis.
↓
H-ions 1st stimulate & then depress SA node leading to tachycardia & bradycardia
respectively.
↓
It also causes parasympathetic stimulation leading to hyperperistalsis & relaxation of anal sphincter with passage
of meconium.
Decreased fetal oxygenation in labor → hypoxia → metabolic acidosis → asphyxia →
tissue damage/fetal death
Investigation for fetal distress
CTG - to detect FHR accelerations- spontaneous or induced
Scalp blood pH
Fetal pulse oximetry
Fetal ECG/ST segment analysis (STAN).
ABGIf acidosis is excluded → monitor labor by testing every 1
/2hrly to exclude acidosis.
If fetus is acidaemic → delivery urgently by safest method (vaginal or abdominal).
Assess fetal condition at birth by ABG of umbilical artery.
a) Normal (mean) values are: pH 7.27, PCO2 50; HCO3 23, base excess – 3.6
Diagnosis of fetal distress
Abnormal fetal heart rate pattern are as follows
Persistent severe variable decelerations
Persistent and non-remedial late decelerations
Persistent severe bradycardia
Meconium staining of the liquor
Early passage of meconium occurs any time before and is classified as trace (+1, +2, +3) and particulate based
on its color and viscosity.
Trace meconium is lightly stained yellow or greenish amniotic fluid.
Meconium of +2 to +3 is dark green or black and is usually thick and tenacious with a pea soup appearance
Abnormal ph < 7.20
Low apgars score at 1 minute
Meconium grading
Meconium grading
Grade 1 MSL: light, slight greenish or yellowish tinge or staining of liquor. Not usually related to fetal
distress and doesn’t cause meconium aspiration syndrome
Grade 2 MSL: moderate khaki green or brownish meconium staining of liquor. Its possible sign of fetal
distress which should be confirmed if associated with abnormal FHR. If present in early labour, its concerning
because baby can inhale it and cause MAS
Grade 3 MSL: Heavy or thick/tenacious, like pea soup, thick green or black liquor colour. It’s a sign of fetal
distress and risk of MAS is very high
nonsurgical Management of Fetal Distress:
a) Lateral positioning avoids compression of vena cava and aorta by gravid uterus. This increases cardiac output
and uteroplacental perfusion.
c) Administer O2 (6-8 L/min) by mask to the mother to improve fetal SaO2.
d) IV fluids (crystalloids) to correct dehydration & improve intravascular volume and uterine perfusion.
e) Correct maternal hypotension (after epidural analgesia) with infusion of 1L of R/L solution.
f) Stop oxytocin to improve fetal oxygenation.
Fetal hypoxia may be due to strong and sustained uterine contractions. But with reassuring FHR and in
absence of fetal acidemia, oxytocin may be restarted.
g) Give tocolytic (Inj terbutaline 0.25 mg SC) if uterus is hypertonus and FHR nonreassuring.
h) Amnioinfusion- process to increase intrauterine fluid volume with warm normal saline (500mL)
Indications and merits for amnioinfusion
indications for amnioinfusion are:
a) Oligohydramnios and cord compression
b) Wash out or dilute meconium
c) To improve variable or prolonged decelerations.
Merits of amnioinfusion: Reduces cord compression, meconium aspiration, improves Apgar score and reduces
rate of C/S
surgical Management of Fetal Distress
surgical:
Do cesarean delivery with a 15° lateral tilt till the baby is delivered.
For confirmed fetal compromise, acceptable as gold standard for decision to delivery interval, is 30 minutes
Pediatrician should be made available during delivery.
