OBSTETRICS FETAL ASSESSMENT
METHODS - NST, VST, CST, BPP &
DOPPLER VELOCIMETRY EXAM Q&A
Why is sleep a confounding factor in fetal assessment and what can be done? -
ANSWER-Sleep cycles lasting 20-80 min. FHR variability is decreased and tracing
likely to be nonreactive. Use longer tracing or VAS.
medications:
What is the effect of maternal glucocorticosteroids given
for fetal maturation of premature lungs that can affect fetal assessment? -
ANSWER-influences the BPP score by lowering AFI , decreasing fetal movement,
decreasing breathing movement
What is the effect of maternal magnesium sulphate that can affect fetal assessment?
- ANSWER-Can decrease FHR variability
What can affect FHR variability - ANSWER-MagSulph, narcotics, sedatives, beta
blockers, maternal smoking, illicit drugs, hypoglycemia
What is the effect of maternal hypoglycemia on the fetus? - ANSWER-may reduce
FHR variability s well as fetal movement and breathing
What is the Cardiff technique? - ANSWER-Patient counts the fetal movements when
she first get up in the morning and records the time for 10 movements. Lack of 10 in
3 hrs requires fetal testing.
What is the Sadovsky technique? - ANSWER-Patient counts movements over 1 hr.
Reassuring if four movements or more. If not then a second hour is permitted but if
four in two hours are not felt fetal testing is required.
What is the follow up test for decreased fetal movements? - ANSWER-Non Stress
Test- cardiotocography
What is the critera for a reactive NST? - ANSWER-At least 2 accelerations in 20
minutes. <32 weeks they should be at least 10 beats above baseline and lasting at
least 10 seconds. At >32 weeks they should be 15 and 15. If nonreactive at 20 min it
should be observed for another 20 min to account for possible sleep.
What is the positive and negative predicitive value of the NST and what is it best
used for? - ANSWER-PPV: 50-70%
NPV: >90%
Best used to rule out rather than predict fetal compromise due to high false positive
rate.
METHODS - NST, VST, CST, BPP &
DOPPLER VELOCIMETRY EXAM Q&A
Why is sleep a confounding factor in fetal assessment and what can be done? -
ANSWER-Sleep cycles lasting 20-80 min. FHR variability is decreased and tracing
likely to be nonreactive. Use longer tracing or VAS.
medications:
What is the effect of maternal glucocorticosteroids given
for fetal maturation of premature lungs that can affect fetal assessment? -
ANSWER-influences the BPP score by lowering AFI , decreasing fetal movement,
decreasing breathing movement
What is the effect of maternal magnesium sulphate that can affect fetal assessment?
- ANSWER-Can decrease FHR variability
What can affect FHR variability - ANSWER-MagSulph, narcotics, sedatives, beta
blockers, maternal smoking, illicit drugs, hypoglycemia
What is the effect of maternal hypoglycemia on the fetus? - ANSWER-may reduce
FHR variability s well as fetal movement and breathing
What is the Cardiff technique? - ANSWER-Patient counts the fetal movements when
she first get up in the morning and records the time for 10 movements. Lack of 10 in
3 hrs requires fetal testing.
What is the Sadovsky technique? - ANSWER-Patient counts movements over 1 hr.
Reassuring if four movements or more. If not then a second hour is permitted but if
four in two hours are not felt fetal testing is required.
What is the follow up test for decreased fetal movements? - ANSWER-Non Stress
Test- cardiotocography
What is the critera for a reactive NST? - ANSWER-At least 2 accelerations in 20
minutes. <32 weeks they should be at least 10 beats above baseline and lasting at
least 10 seconds. At >32 weeks they should be 15 and 15. If nonreactive at 20 min it
should be observed for another 20 min to account for possible sleep.
What is the positive and negative predicitive value of the NST and what is it best
used for? - ANSWER-PPV: 50-70%
NPV: >90%
Best used to rule out rather than predict fetal compromise due to high false positive
rate.
