Antepartum fetal testing Flashcards
Criteria for reactive non-stress test
- 2 or more accelerations within 20 minutes (up to 40 minutes can be tried)
- acceleration = 15 bpm or more elevation lasting 15 seconds or more (after 32 weeks), 10 x 10 before 32 weeks
Criteria for BPP
NST (reactive)
Breathing (1 episode of 30 seconds)
Tone (1 flexion/extension or opening/closing hand)
Gross movement (3 movements of limb or body)
Amniotic fluid (2 cm vertical pocket)
What percent of NSTs will be non-reactive between EGA 24-28 weeks? 28-32 weeks?
24-28 weeks: 50%
28-32 weeks: 15%
50% NSTs will have variables
What is the positive predictive value of NST?
10%
what is the likelihood of stillbirth after negative test?
Within 1 week:
NST: 1.9 in 1,000
CST/BPP/mBPP: 0.3 and 0.8 (x2) in 1,000
what is the negative predictive value for NST, CST, BPP, modified BPP, umbilical artery doppler?
- 8% for NST
99. 9% for CST, BPP, mBPP
How is CST performed, what are possible findings?
Minimum of 3 ctx lasting 40 seconds over 10 minutes.
Pt in lateral recumbent position
Can be spontaneous, by nipple stimulation or IV oxytocin
Possible results:
negative: < 50% late decelerations after ctx
positive: > 50% lates with ctx
equivocal-suspicious: intermittent lates, significant variables
equivocal: decels in the presence of ctx q2m lasting 90s or more
unsatisfactory: less than 3 ctx in 10 m
BPP scores and associated management
8-10 -> normal -> expectant
6 -> equivocal -> term: delivery, preterm, repeat in 24 hours
4 or less -> abnormal deliver; if less than 32 weeks consider observation/extended monitoring
Oligo always requires further eval. MVP better than AFI based on RCTs (fewer interventions, no worsening outcome) - Grade A evidence
What is a modified BPP?
MVP + NST; reflection of long term and short term acid base status
When should umbilical artery velocimetry be used?
in cases of growth restriction, in junction with other antenatal testing modalities (grade A evidence)
When do you start antenatal testing?
Typically no earlier than 32 weeks, with high risk conditions can be modified - Grade B evidence
How often do you perform antenatal testing?
If persistent condition requiring antenatal testing, then typically 1-2x week. If self limited (i.e. decreased fetal movement), then 1 time. Grade B evidence
How do you manage abnromal NST?
Typically with BPP or CST - Grade B evidence
How do you manage persistent oligohydramnios (with intact membranes)
Typically delivery 36-37 weeks; in cases less than 36 weeks decision should be individualized. Grade C evidence
