This document summarizes various diagnostic fetal assessment tests, including chorionic villous sampling, triple or quad screening, ultrasound, placental grading, amniocentesis, cordocentesis, amnioreduction, fetal MRI, fetal echocardiogram, and vibroaccoustic stimulation. It describes what each test is, how it is performed, what it can detect, risks, timing considerations, and references for further information. The goal of these tests is to evaluate the health and development of the fetus during pregnancy.

1. Diagnostic Fetal Assessment
tests
Sandy Warner RNC-OB, MSN
August 3, 2011
Inpatient Review Class

2. 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

3. 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

4. Ultrasound
 Developed in WWII with submarines
 Diagnostic use since 1950s
 Definition: transmission of sound
waves to investigate an object
 (Kline-Fath & Bitters, 2007)

6. 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

8. Amniocentesis
 Trans-abdominal needle aspiration of
10-20 ml of amniotic fluid for lab
analysis
 Done under ultrasound
 Requires sterile technique and time out

9. Amniocentesis
 Indications:
 Genetic
 R/O infection
 Fetal lung maturity
 Assess for bilirubin with hemolytic
incompatibility

10. 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)

11. 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

12. Cordocentesis /
Fetal Blood Transfusion

13. 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

14. Amnioreduction

15. 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)

16. 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)

17. 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)

18. 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

19. 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

20. 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.

21. Vibroaccoustic Stimulation
(VAS)

22. 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