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Diagnostic Tests. By Prof. Unn Hidle Updated Spring 2010. ULTRASOUND. Ultrasound. Description Outlines and identifies fetal and maternal structures (uses high frequency sound-waves) Assists to confirm estimated date of delivery Implementation

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diagnostic tests

Diagnostic Tests


Prof. Unn Hidle

Updated Spring 2010

  • Description
      • Outlines and identifies fetal and maternal structures (uses high frequency sound-waves)
      • Assists to confirm estimated date of delivery
    • Implementation
      • Previously, the test used to be done with a full bladder (drink 6-8 glasses of water pre-test), but with high-tech ultrasound, it is usually no longer necessarry.
      • Inform the client that the test presents no known risks to client or fetus
      • Aspiration of amniotic fluid done from 14 weeks of pregnancy and on
      • Performed to determine genetic disorders (after AFP), the sex of the fetus, and fetal lung maturity (L/S ratio - this is later in pregnancy)
    • Risks
      • Maternal hemorrhage
      • Infection
      • Rh isoimmunization
      • Abruptio placentae
      • Amniotic fluid emboli
    • Instruct client to empty bladder before procedure
    • Prepare client for ultrasound, which is performed to locate the placenta
    • Obtain baseline vital signs and FHR, and monitor every 15 minutes
    • Position client supine
    • Instruct client that if chills, fever, leakage of fluid at the needle insertion site, decreased fetal movement, or uterine contractions occur, to notify the physician or health care provider
Chorionic Villus Sampling (CVS)
    • Description
      • Aspiration of a small sample of chorionic villus tissue at 8 to 12 weeks' gestation
      • Test is performed for the purpose of detecting genetic abnormalities
    • Implementation
      • Usually, the client is instructed to drink water to fill the bladder before the procedure to aid in the position of the uterus for catheter insertion
      • Instruct the client to report bleeding, infection, or leakage of fluid at insertion site after procedure
      • Rh-negative women may be given RhoGAM for risks related to the procedure
Endo-vaginal ultrasound used to locate area to insert catheter into uterus through the maternal abdomen for skin and blood samples:
    • Percutaneous umbilical blood sampling (PUBS)
  • Fetal blood is used to help diagnose conditions such as hemophilia, congenital rubella, toxoplasmosis, etc.
computer axial tomography



non stress test20
Non-stress test
  • Description
      • Performed to assess placental function and oxygenation
      • Determines fetal well-being
      • Evaluates fetal heart rate (FHR) in response to fetal movement
    • External ultrasound transducer and the tocodynamometer (toco) are applied to the mother and a tracing of at least 20 minutes’ duration is obtained so that the FHR and the uterine activity can be observed
    • Obtain baseline blood pressure and monitor BP frequently
    • Position mother in the left lateral position to avoid vena cava compression (reality: SUPINE!!!!)
    • Ask mother to press a button every time she feels fetal movement
    • The monitor records a mark at each point of fetal movement, which is used as a reference point to assess FHR response
    • Reactive Nonstress Test (Normal/Positive)
      • Indicates a healthy fetus
      • Two or more fetal heart rate accelerations of at least 15 beats per minute, lasting at least 15 seconds from the beginning of the acceleration to the end in association with fetal movement, during a 20-minute period
    • Nonreactive Nonstress Test (Abnormal/Negative)
      • No accelerations or accelerations of less than 15 beats per minute or lasting less than 15 seconds in duration for a 40-minute observation
    • Unsatisfactory
      • Cannot be interpreted because of the poor quality of the FHR
      • Assesses placental oxygenation and function
      • Determines fetal ability to tolerate labor and determines fetal well-being
      • Fetus is exposed to the stressor of contractions to assess the adequacy of placental perfusion under simulated labor conditions
      • Performed if non-stress test is abnormal*** REALITY: VERY RARELY used anymore since it is so risky!
    • The external fetal monitor is applied to the mother and a 20 to 30-minute baseline strip is recorded
    • The uterus is stimulated to contract either by the administration of a dilute dose of oxytocin (Pitocin) or by having the mother use nipple stimulation (very rare!) until 3 palpable contractions with a duration of 40 seconds or more in a 10-minute period have been achieved
    • Frequent maternal BP readings are done and the client is monitored closely while increasing doses of oxytocin are given
    • Negative Contraction Stress Test (Normal)
      • Represented by no late or variable decelerations of the fetal heart rate
    • Positive Contraction Stress Test (Abnormal)
      • Represented by late or variable decelerations with 50% or more of the contractions in the absence of hyperstimulation of the uterus
    • Equivocal
      • Contains decelerations, but with less than 50% of the contractions, or the uterine activity shows a hyperstimulated uterus
    • Unsatisfactory
      • Adequate uterine contractions cannot be achieved, or the FHR tracing is not of sufficient quality for adequate interpretation
fetal biophysical profile30
Fetal Biophysical Profile
  • Overall, evaluates fetal status
  • Assesses 5 fetal variables:
    • FHR with activity = reactive NST
    • Amniotic fluid volume
    • Fetal tone (flexion and extension of extremities)
    • Movements of body or limbs
    • Fetal breathing movements (oxygenation)
maternal serum studies some of these will be discussed in details throughout the course
MATERNAL SERUM STUDIES*** Some of these will be discussed in details throughout the course
  • HCG
  • T= Toxoplasmosis
  • O= Other (HIV, HIB, Variella, parovirus, syphillis, etc)
  • R= Rubella
  • C= Cytomegalovirus (CMV)
  • H= Herpes Virus Type II
alpha fetoprotein screening afp
Alpha-Fetoprotein Screening (AFP)
  • Description
      • Assesses the quantity of fetal serum proteins and if elevated is associated with open neural tube and abdominal wall defects
      • Can detect spina bifida (elevated) and Down’s syndrome (decreased)
    • Implementation
      • Explain that the level is determined by a single maternal blood sample drawn at 15 to 18 weeks' gestation
      • If the level is elevated and the gestation is less than 18 weeks, a second sample is drawn
      • An ultrasound is performed when the level is elevated to rule out fetal abnormalities or multiple gestation
estriol level
Estriol Level
  • Primary estrogen secreted by the placenta
  • Measurements are used to assess placental functioning and fetal viability
  • Not a routine test
  • Done @ 28 weeks and Q week thereafter
  • Low levels = fetoplacental deterioration
triple marker screening
Triple-Marker Screening
  • Includes:
    • Human Chorionic Gonadotropin (HCG)
    • Unconjugated estriol
    • MSAFP (Maternal Serum AFP)
  • Screen for chromosomal abnormalities
  • Increases detection of Trisomy 18 (Edward’s syndrome) and Trisomy 21 (Down’s syndrome)
  • Test is positive if:
    • Decreased Estriol and MSAFP
    • Increased HCG
  • Amniocentesis is offered if positive
now also a quadruple screen
Now, also a Quadruple screen
  • Fairly new!
  • Combines the triple screen and a test for the hormone inhibin A, which is produced by the fetus and the placenta
  • One large study of over 23,000 women has reported that the quadruple screen detects almost 86% of all Down syndrome cases. Based on this study, the quadruple test is more likely to pick up Down syndrome and may be less likely to be false-positive than the triple screen
summary findings
Summary findings:
  • AFP: Increased = Neural Tube Deformity Decreased = Down’s syndrome
  • HcG: Increased = Down’s syndrome
  • Estriol: Decreased = Down’s syndrome
  • Inhibin A: Increased = Down’s syndrome
  • All findings, including type and amount of elevated or decreased levels, are evaluated to determine the risk for potential outcomes.
other tests
Other tests……
  • Kick Test (Fetal Movement Counting)
    • Description
      • Mother lies down on the left side for 1 hour after meals and counts fetal kicks for 30 minutes
      • Instruct client to notify physician or health care provider if there are fewer than 5 kicks in 1 hour