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