Fetal Diagnostic Testing (unit 3) Flashcards Preview

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1

diagnostic testing

•used to evaluate fetus for genetic/congenital disorders
•genetic screening, amniocentesis, etc

2

antepartum testing

•done AFTER problem is detected and goal is to evaluate how fetus is tolerating
•NST, kick counts, U/S, etc

3

ultrasound

•produces image based on echos
•visualization of fetus and surrounding structures
•dark spots= fluid
•white spots= tissue
•transabdominal or transvaginal
*need full bladder for transabd. if < 20 wk

4

best U/S for viewing internal organs

•2D

5

biggest risk of U/S

•missing something

6

benefit of 3D U/S

•identifying cleft lift and palate

7

standard U/S

•general survey of fetus, amniotic fld.

8

specialized U/S when...

•abnormalities exist on basic U/S
•MSAFP
*hx of congenital abnormality

9

limited U/S when...

•need specific info needed
•emergency
•testing BPP, AFI, fetal weight, fetal position, confirmation of cardiac activity

10

1st trimester U/S

•transvaginal- uterus, gest. sac (6-8 wk), embryo
•used to
-detect ectopic (transvag)
-multifetal
-confirmation (FHR @ 6-7 wk)
-gestational age (BPD)

11

2nd trimester U/S

*standard U/S
•trasnabdominal
•confirm GA/fetal viability
•evaluate fetal anatomy
•locate placenta
•detect congenital abnormalities
•assist w/ PUB or amnio

12

3rd trimester U/S

•confirm viability
•detect macrosomia/IUGR
•fetal position
•AFV, fetal breathing/activity
•amnio or BPP

13

fetal sex determination via U/S

•after 18 wks

14

GA assessment via U/S

•most accurate if done early (1st trimester)

15

how does 2nd trimester U/S compare to LMP

•not very accurate at that point b/c there can be a difference of 1-2 wks

16

when is crown to rump embryo length most accurate

•7-12 wk

17

positioning U/S

•wedge under hip in late trimesters
•lithotomy for transvag

18

screening tells us...

•there is a RISK of an issue

19

diagnostic tells us...

•there IS an issue

20

Alpha-Fetoprotein Screening (MSAFP)

•fetal liver protein (AFP) produced in predictable amnt. until 20 wks
•maternal serum tested for anomolies @ 16-18 wks
*key mom blood determinant screening

21

MSAFP anomalies

•80% open NTD and open abd wall defects
•33% trisomy 21

22

factors that influence MSAFP results

•GA (validity affected if really off on dates)
•maternal weights
•race
•maternal dz

23

what does MSFP detect

•spina bifida
•ancephaly

24

anecephaly

•no brain
•folic acid supp prevent
•95% fatal
•organ donor

25

triple marker test

•MSAFP+hCG+Estriol
•80% detection ONTD
•60% detection trisomy 21
•50% detection trisomy 18

26

quad screen

•maternal AFT (fetal liver protein)
•hCG (placenta hormone)
•unconjugated estriol (uE3)- fetus/placenta protein
•inhibin A (ovaries/placenta protein)
*anomalies associated w/ preterm, IUGR, preeclampsia, fetal loss

27

nunchal transluscency

•1st trimester screening (10.5-13.5 wk)
•looking for free hCG/PAPP-A levels
•combined w/ fld. collection from fetus neck
•screening test- NOT diagnostic

28

elevated AFP d/t...

•**open neural tube defect
•mutifetal gestation
•abd. wall defect
•renal anomalies
•maternal IDDM

29

low AFP d/t...

•overestimation of GA
•trisomy 21
•hydatiform mole

30

what happens if MSAFP abnormal

•lots of false neg. so need further/other testing
•further testing w/ specialized U/S, genetic specialists, etc

31

amniocentesis

•needle inserted into uterus and amniotic fld. withdrawn
•used if
-maternal age > 35
-family/past hx of genetic disorder
-abnormal AFP/EDC
-PG after 3+ SAb
*done after 14 wk

32

risks w/ amniocentesis

•ROM, labor, miscarriage
•fetal cord injury
•infection
•abruption
•fetal death (rare)
•Rh isoimmunization
•amniotic fld. embolism

33

what amniocentesis detects

•fetal karyotype
•fetal AFP or AChE
•fetal Rh sensitization

34

3rd trimester amniocentesis

•assess fetal lung maturity if delivery considered before 38 wks
•diagnose fetal hemolytic dz d/t maternal Rh sensitization

35

fetal lung maturity

•L/S 2:1 (3:1 in diabetic mom) AND PG positive = mature
•PG neg = RDS

36

diagnosing fetal hemolytic dz

•done if mom antibody 1:8 or more
•high levels of bili in amnio fld. if positive

37

RN consideration amniocentesis

•supine w/ hip wedge
•bladder EMPTY
•monitor fetal status
***Rhogam after if needed
•karyotype takes weeks
•educate s/sx of infection/bleeding
•encourage fld intake

38

chronic villus sampling

•1st tri alternative to amniocentesis
•genetic testing @ 10-12 wks (earliest)
•sample from fetal placenta
•higher risk than amnio (limb defect)
•need FULL bladder
•Rhogam post procedure if Rh-
•transabdominal or transvaginal

39

Percutaneous umbilical blood sampling (PUBS)

•collecting fetal blood by fetoscope via umbilical vein under U/S guidance
*normally have to do in OR b/c often have to get baby out ASAP

40

indications for PUBS

•blood/chromosomal disorders
•evaluate isoimmune fetal hemolytic anemia/need for transfusion

41

Cordocentesis (blood studies)

•PUBS method
•Kleihaur Betke test- ensures blood from fetus
•CBC
•IC for Rh
•blood gases
•karyotyping

42

PUBS risks

•preterm labor
•amnionitis
•cord laceration

43

third trimester testing

•goal to evaluate whether intrauterine environment is supportive to fetus
•if not, deliver baby ASAP

44

nonstress test (NST)

•primary means of EFM fetal surveillance if increased risk of UPI
•used if
-IDDM mom
-PIH
-IUGR
-previous stillbirth
-post term
-dec. fetal movement
*report as reactive or non-reactive

45

healthy fetus w/ intact CNS will have...

•accels w/ movement
•indicates CNS fxn

46

reason for NST false non-reactive

•fetal immaturity
•sleep cycles
•medications
•chronic smoking

47

Reactive (normal) NST

•normal FHR w/ avg. variability
•> 32 wk- at least 2 FHR acc. of 15 bpm lasting 15 sec w/in 20 min
•28-32 wk- at least 2 FHR acc of 10 bpm lasting 10 sec w/in 20 min
*may have to wake baby w/ vibroaccoustic stim

48

Non-reactive (abnormal) NST

•doesn't meet FHR acc. criteria in 2 attempts (40 min)
•requires further testing in L&D
-CST or BPP
•may have to induce

49

contraction stress test (CST)

•assesses FHR response to stress
•requires EFM and induction of ctx
-pitocin
-nipple stimulation
•more accurate than NST
*invasive

50

negative (normal) CST

•no late decelerations
•minimum of 3 tx for 40-60 sec duration over 10 min
*reassurance that fetus will likely survive labor and that labor will occur in 1 wk

51

positive (abnormal) CST

•late decels in 50% of > ctx
•indicates UPI
•requires induction/c-section (baby out ASAP)
*POSITIVE=PROBLEMS

52

CST contraindications

•preterm
•placental malplacement
•multiple gestation
•prior C/S w/ classic incision (vertical)
-r/o uterine rupture

53

biophysical profile (BPP)

•U/S and EFM
•accurate indicator of impending fetal death
•5 parameters
-FHR (NST)
-fetal breathing movements
-fetal tone
-amniotic fld. vol. (AFV)
*less invasive than CST

54

fetal hypoxia leads to...

•alteration in movement, breathing, HR

55

scoring of BPP

•0 OR 2 for each of the 4 parameters
-FHR (NST)
-fetal breathing movements
-fetal tone
-amniotic fld. vol. (AFV)
•normal indicates CNS fxn and no hypoxia
•abnormal and low fld. means labor needs to be induced

56

BPP numerical interpretations

•8/8- normal BPP didn't do NST
•8/10- normal BPP and non-reactive NST
•10/10-normal BPP and reactive NST

57

equivocal BPP

6
*repeat 24 hr

58

abnormal BPP

4 or less
*induce/c-section

59

amniotic fluid index (AFI)

•fluid pocket measurement
•detects polyhydramnios & oligohydramnios

60

polyhydramnios

•AFI > 25
•d/t
-NTD
-GI obstruction
-twins
-hydrops
-DM
*r/o PTL, ROM -> cord prolapse

61

oligohydramnios

•AFI < 5
•associated w/ ROM
•r/o
-renal abnormalities
-IUGR
-cord compression
-deformity
-hypoplastic lungs

62

doppler blood flow analysis

•see how well baby being perfused

63

fetal kick count instructions

•eat
•lay on side peacefully
*should feel 10 movements in 2 hrs
*no move w/in 12 hrs warrants further testing