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Diagnostic Fetal Assessment tests
Sandy Warner RNC-OB, MSNAugust 3, 2011
Inpatient Review Class
Prenatal Assessments and screening
Chorionic Villous sampling: 10-12 wk using U/S to aspirate
trophoblastic tissue Can be done either transabdominally
or transvaginally Detects chromosome abnormality Risks: miscarriage, bleeding,
infection & PROM
Prenatal Assessments and screening cont.
Triple or Quad Screen Blood drawn between 15-20 wks Can detect Down’s syndrome, other
chromosomal abnormalities and neural tube defects
Values of blood tests added together to determine risk
Screening tool – further testing needed for definitive diagnosis
Ultrasound
Developed in WWII with submarines
Diagnostic use since 1950s
Definition: transmission of sound waves to investigate an object
(Kline-Fath & Bitters, 2007)
Placental grading Grade 0 – smooth, dense w/o
echogenic areas Grade 1 – undulations present,
some echogenic areas Grade 2 – deeper and >
indentations, more echogenic areas Grade 3 – dense echogenic areas w/
indentations, areas of calcification
Amniocentesis
Trans-abdominal needle aspiration of 10-20 ml of amniotic fluid for lab analysis
Done under ultrasound Requires sterile technique and
time out
Amniocentesis
Indications: Genetic R/O infection Fetal lung maturity Assess for bilirubin with hemolytic
incompatibility
Amniocentesis
Timing: Early – performed between 11-14 wks
Significantly higher pregnancy loss Post procedure fluid loss
2nd trimester – performed between 15-20 wks
Usually for genetic screening
3rd trimester Usually for fetal lung maturity
(Gilbert, 4th edition, pg 93)
Cordocentesis / Fetal Blood Transfusion
Blood Transfusion for anemia
How much blood is given?
Graph is used correlating the hematocrit of donor blood to the hematocrit of the fetus to determine donor blood volume to be given
Cordocentesis / Fetal Blood Transfusion
Amnioreduction
Reduces amount of amniotic fluid around fetus
Procedure like amniocentesis only with tubing to suction canister or stopcock
Done to relieve maternal symptoms or with twin to twin transfusion syndrome
Amnioreduction
Fetal MRI Superior soft tissue contrast test Does not use radiation Used for fetal brain, spinal deformities,
lesions, masses Also can assess placental and cord
malformations Also used to measure lung volume
Research still continuing for PPROM pts (Kline-Fath & Bitters, 2007)
Fetal MRI Con’t Not recommended in first trimester
(no documented studies on harm from heat or sound, but not recommended)
Not used routinely, only after U/S not able to detect
Contrast dye not recommended
Informed consent (Kline-Fath & Bitters, 2007)
Fetal Echocardiogram Timing: between 18-22 weeks Indications:
Family history congenital heart defects Maternal diabetes Drug exposure Teratogenic exposure Chromosomal abnormalities Non-immune hydrops Maternal PKU Fetal arrhythmias
Queenan, Hobbins & Spong (4th edition, 2007)
Vibroaccoustic Stimulation (VAS)
Artificial acoustic stimulation
Done after 25 wks gestation when fetus can hear
After 10 minutes of baseline and no accelerations, place the artificial larynx on the maternal abdomen over the fetal head
Vibroaccoustic Stimulation
Provide 5-10 sec stimulation near fetal head, wait one minute
If no acceleration repeat cycle for a total of three times
if non-reactive after 40 minutes, proceed with further evaluation
Vibroaccoustic Stimulation
Fetuses 28 weeks or greater respond to VAS with a consistent increase in heart rate.
Observed changes are greater as term is approached.
Vibroaccoustic Stimulation (VAS)
References
Gilbert, E. S., (2011) 5th edition Manual of High Risk Pregnancy and Delivery.
Kline-Fath, B. & Bitters, C. (2007) “Prenatal Imaging” Newborn and Infant Nursing Reviews, Vol.7, No. 4.
Mattson, S. & Smith, J.E., (2011) 4th edition Core Curriculum for Maternal-Newborn Nursing.
Queenan, J.T., Hobbins, J. C., & Spong, C. Y. (2005) 4th edition, Protocols for High-Risk Pregnancies