Flashcards in Antepartum Assessment Deck (47):
When/why is the first ultrasound in pregnancy?
7 wks- confirm pregnancy, exclude ectopic or molar pregnancy, confirm cardiac pulsation, crown-rump length (dating)
When/why is second ultrasound in pregnancy?
Look for congenital malformations, verify dates/growth, placental position
When/why is third ultrasound in pregnancy?
Evaluate fetal size, assess fetal growth, verify fetal position
What/when can you see on early ultrasounds?
4.5 wks- gestational sac
5 wks- yolk sac
5.5 wks- embryo
6-7 wks- heartbeat and blood flow
7-13 wks- crown-rump length
13 wks- biparietal diameter
14 wks- femur length
What measurements are used for dating/ how accurate are they?
CRL (early first tri) +/- 4.7 days
BPD/HC/AC/FL up to 22 wks +/- 1wk
^ up to 30 wks +/- 2wks
After 30 wks +/- 2-3wks
When are EFW and growth scans done?
If fundal ht lags/exceeds EGA by EDD
*accuracy is low
HC/AC ratio is good predictor for IUFGR
What is the only caution with ultrasound?
Can increase body temperature
(Significant only for long exposure time)
When is a NST considered reactive?
2 access in 20 minute period, 40 minute max testing, plus normal baseline and moderate variability
What do you need to know about vibroacoustic stimulation?
Sound stimulus applied for 3 seconds
Reactive accel correlates with nonacedemic fetus
Decreased effect in preterm or once ruptured
What do you need to know about scalp stim?
Rule out metabolic acidemia
Not to fontanels
Done between contractions
Accel good predictor of non-acidemic
Lack of accel poor predictor of acidemic
What do you do if you get a non reactive NST?
BPP or CST
What is a CST?
3 ctx in 10 minutes with oxytocin or nipple stim
What are the possible results of CST?
Negative- no late decels
Positive- recurrent lates
Suspicious- intermittent lates or variables
Unsatisfactory- poor tracing or not 3 ctx
What do you do if you get a nonreactive negative CST?
Repeat in 24 hrs
What do you do if you get a positive CST?
BPP, consider delivery
What do you do if you get a suspicious or unsatisfactory CST?
Repeat in 24 hrs
What are the components of a BPP/ when do they develop?
Fetal tone (7-8wks)
Fetal movement (9wks)
Fetal breathing movements (20-21wks)
Reactive NST (28-32wks)
What is a score of 2 for fetal breathing movements in a BPP?
1 or more episodes >30 seconds within 30 minutes
What is a score of 2 for gross body movements in a BPP?
3 or more limb/body movements within 30 minutes
What is a score of 2 for fetal tone in a BPP?
1 or more episodes of extension/return to flexion of limbs or trunk (or open/close of hands)
What is a score of two for qualitative AFV in a BPP?
1 or more pockets of fluid measure 2 or more cm
What is each parameter of a BPP regulated by?
first to appear, last to disappear with fetal asphyxia
How does ultrasonography work/ what is it used for?
Used by sound waves
Used to date, anatomy of fetus, examine placenta and amniotic fluid
Also used to assist in procedures (ie amnio)
What is the interpretation/follow up for a BPP score of 8 or 10?
Normal, low risk for chronic asphyxia
Repeat weekly or 2x/wk
What is the interpretation/follow up for a BPP score of 4-6?
Suspect chronic asphyxia
If 36wks or >, deliver
If under 36wks repeat in 4-6hrs
What is the interpretation/follow up for a BPP score of 0-2
Abnormal; strongly suspect chronic asphyxia
How do you measure AFI?
Measure largest pockets of fluid (without cord) in each quadrant
What is a normal AFI at term?
How is oligo or poly diagnosed?
AFI 95th percentile for EGA
Why does oligo sometimes mean chronic hypoxia?
Fetus spares head heart and adrenals
Kidneys poorly perfused
Dec urine output
*takes about 13 days for AFI to go from normal to oligo with fetal compromise
What is a modified BPP?
NST plus AFI
Reactive and at least 5cm
What is the most common expectation with fetal movement counts?
10 movements in 2 hrs
What should you know about umbilical artery Doppler velocimetry ?
Measures velocity of blood flow in umbilical artery
During systole flow is high
During diastole flow slows down *should not stop
What is an amniocentesis?
Small spinal needle inserted transabdominally to collect amniotic fluid sample under ultrasound
Sample used for genetic testing, assessment of fetal lung maturity, other testing
Can be used to reduce fluid with poly
Done after 15 wks
What is chorionic villus sampling?
Sample of placental villi at 10-13 wks
Obtained by inserting catheter transcervically
Tested for genetic disorders
What is cordocentesis?
Also called percutaneous umbilical cord blood sampling
Umbilical vein punctured for blood sample
Used to test for genetic and blood disorders
Largely replaced by placenta biopsy
How do you test fetal lung maturity?
Usually require amniocentesis
FLM or TDx
If FLM immature, then L/S ratio done
PG can be done with L/S ratio to inc reliability
What is trisomy 21?
Mental retardation, facial abnormalities
What is trisomy 18?
Median lifespan 5-15 days
Heart, kidney, internal organs anomalies
What is the first trimester genetic screening?
Detects inc risk of trisomy 21
Ultrasound measures nuchal translucency
Maternal serum measurements (PAPP-A, hCG)
Inc NT, inc hCG, dec PAPP-A predict trisomy 21
What is 2nd trimester genetic screening?
Detects trisomy 18, trisomy 21, and NTD's
Most common is quad screen:
Alpha fetoprotein (AFP)
Unconjugated estriol (uE3)
Trisomy 18- AFP, uE3, hCG all dec
Trisomy 21- AFP, uE3 dec, hCG, inhibin A inc
NTD's - AFP inc
Tay-Sachs, Canavan disease