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Fetal Monitoring. RC 290. Estriol. By-product of estrogen found in maternal urine Production requires functional placenta and fetal adrenal cortex Levels increase as pregnancy progresses Low or absent levels may indicate fetal demise or anencephaly
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Fetal Monitoring RC 290
Estriol • By-product of estrogen found in maternal urine • Production requires functional placenta and fetal adrenal cortex • Levels increase as pregnancy progresses • Low or absent levels may indicate fetal demise or anencephaly • Levels checked in maternal urine or plasma
Amniocentesis • Amniotic fluid is withdrawn via ultrasound-guided needle aspirations • High yield with low occurrence of risk • Puncture of fetus, umbilical cord or placenta • Infection • Spontaneous abortion
Amniocentesis Findings • Bilirubin levels – presence of RH disease • Creatinine levels – normally increase as gestation progresses • Shows maturation of fetal kidney • Cellular exam – identify genetic and chromosomal abnormalities
Amniocentesis (cont.) Presence of meconium • Usually seen in term or post-term babies • Indicates episode(s) of intrauterine stress, eg, hypoxia or asphyxia • Fetus may aspirate which will cause respiratory distress after delivery
Amniocentesis (cont.) • L/S ratio: compares amount of lecithin to sphingomyelin in amniotic fluid • Assesses maturity of fetal lungs and surfactant • An L/S ratio of 2:1 shows fetal lung and surfactant maturity • Normally occurs at 35 weeks gestation
Shake Test • Various mixtures of amniotic fluid, ETOH and saline are shaken so that a bubbly froth forms • Test evaluates the ability of lecithin to create a stable foam in the presence of ETOH • Is simpler and less costly than L/S ratio
Surfactant Maturation Normally occurs at 35 weeks when L/S ratio hits 2:1
Any chronic, low grade stress will accelerate surfactant maturation L/S ratio hits 2:1 before 35 weeks
Smoking Maternal respiratory problems Maternal diabetes (usually type I) Maternal anemia Maternal hypertension Maternal infection Maternal narcotic use Maternal malnutrition PROM – Premature Rupture of the Membrane Also makes infant prone to hypothermia and infection Placental problems Placenta Praevia Placenta Abruptio Accelerated Surfactant Maturation
Delayed Surfactant Maturation L/S Ratio 2:1 AFTER 35 weeks • Type II diabetes • Fetal RH disease • Chronic glomerulonephritis • Acute, severe hypoxia, hypoglycemia, or hypothermia
DMS • Ultrasound used to assess fetal growth and maturity • Sometimes determines gender of fetus! • Non-invasive so should not harm mother or fetus
Fetal Heart Rate Monitoring • FHR monitored during uterine contractions • Normal rate is 120-160 • Fetal response to hypoxia is bradycardia!
Early Decelerations • Due to increased ICP causing vagal stimulation • Usually benign
Late Decelerations • Bad sign! Indicates uteroplacental insufficiency • Fetus is becoming hypoxic due to decreased maternal blood flow to IV spaces during contractions • Mother is given O2, fluids (if she is hypotensive) and beta-2 stimulants to relax uterine contractions
Variable Decelerations • Most commonly seen • Caused by compression of umbilical cord • Mother’s position is changed
High Risk Delivery and Fetal Rescue if: • Late decelerations • Variable decelerations where heart rate drops to 60 or less and stays there for one minute or longer • Will require C-section and resuscitation
Contraction Stress Test • Pre-labor test to check for UPI • Oxytocin (Pitocin) administered to stimulate contractions • Positive test if two episodes of late decelerations are seen within ten minutes • Positive test indicates impending fetal asphyxia when labor starts!
Fetal Scalp pH • If scalp pH is less than 7.20 on two consecutive samples, then fetus is hypoxic • Used in conjunction with FHR • Falsely low if mother has low pH • May be caused by inadequate fluids or • Prolonged labor with muscle fatigue
