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Amniocentesis Amniotic fluid is withdrawn via ultrasound- guided needle aspirations High yield with low occurrence of risk –Puncture of fetus, umbilical cord or placenta –Infection –Spontaneous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

Accelerated Surfactant Maturation 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

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 –Fetal response to hypoxia is bradycardia!

External (Doppler) FHR Monitoring

Internal FHR Monitoring

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

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