Clin Lab: Pregnancy Flashcards
Pregnancy can be confirmed by:
- Detection of hCG
- Detection of pregnancy via US
- Detection of fetal heartbeat
What do you use measure hCG?
serum or urine
When does hCG production begin?
21 - 23 days of cycle after fertilization of ova
Describe the testing for hCG?
- Serum tests detect lower levels of HCG – can detect pregnancy earlier
- Home urine tests are least sensitive
Qualitative test are done unless looking for…
ectopic pregnancy or threated abortion
With a normal pregnancy, what should happen to hCG levels?
double every 48 hours
HCG peaks around ____, then declines
10-12 weeks
Is a FU required?
No, unless concern for non-uterine pregnancy or if pt has an IUD
Reasons why HCG might not increase appropriately?
- Ectopic pregnancy
- Non-viable fetus
- Molar pregnancy
List the imaging that can be done during pregnancy
- US
- MRI
- CT or X-ray
Describe the USs that can be done during pregnancy
- transvaginal
–> done earlier in preg - transabdominal
–> done later in preg
What can be evaluated with a transvag US?
- presence of intrauterine preg
- Measurement of crown-rump length
- cardiac activity in 1st trimester
- cervix length
What can be evaluated with a transvabdo US?
- biometrics – growing appropriately
- developmental issues, ex - neural tube defects; Hydrops fatalis
- amniotic fluid volume
- fetal growth / estimate weight (gestational DM; IUGR)
Are there any specific contraindication for a MRI during pregnancy?
No
Should you use MRI contrast when pregnant?
avoid if possible
Are CTs or X-rays radiation dangerous during pregnancy?
radiation likely too low to cause significant risk to the fetus, but discuss risks/benefits & alt if poss
Describe CT/X-ray contrast use in pregnancy?
- oral contrast is okay
- IV contrast if necessary
Labs typically ordered at first prenatal visit?
- Blood type
- CBC
- UA w/ culture - infx
- Serology testing for varicella & rubella (unless already done)
- STD/Infx panel – HIV, syphilis, chlamydia, hepatitis B
- As indicated – thyroid function, DM screening, lead screening, other infx dz
What are chromosomal disorders also called?
aneuploidy
What are the 2 types of genetic conditions tested for during pregnancy?
- chromosomal disorders
- carrier disorders
What are the 1st trimester screening tests of genetic disorders?
- serum free β-hCG
- pregnancy-associated plasma PRO (PAPP-A) + US of nuchal translucency (NT)
What are the 2nd trimester screening tests of genetic disorders?
- serum tests for hCG
- unconjugated estradiol
- AFP
- inhibin A
What are the integrated screening tests of genetic disorders?
- Uses both 1st & 2nd trimester screening tests
- Serum integrated test – uses all tests except US of NT
What are the diagnostic tests of genetic disorders?
Karyotyping
What are the 2 ways to get sampling for karyotyping?
Chorionic villus sampling –> sampling of placenta to obtain chromosomes
–> Amniocentesis –> sampling of amniotic fluid
What are the 2 most common chromosomal issues?
- down syndrome (trisomy 21)
- Trisomy 18
What test differentiates trisomy 21& trisomy 18 & describe the levels ?
hCG levels
–> elevated in trisomy 21 –> decr in trisomy 18
What carrier screening look for?
common genetic disorders
What are some examples of screened genetics disorders? & give ex/explain.
- CF
- Hemoglobinopathies (ex = SCA, thalassemias)
- Tay-Sachs dz – can’t process lipids–>build up–>damage/death of neurons
- Fragile X syndrome – alcohol ingestion early during pregnancy
What is fetoscopy?
Direct visualization of the fetus via scope inserted into amniotic sac
Can uses fetoscopy for procedures?
YES
Indications for fetoscopy
- Repair of neural tube defects
- Release of amniotic bands
- Tx for twin-twin transfusion syndrome (TTTS)
In TTTS, explain risk for each baby?
- extra BVs–> CHF
- lacking BVs–> failure to thrive
If A1C is ___ in pregnancy on prenatal screening, what is the dx?
- > /= 6.5
- overt DM
What is used for the detection of gestational DM? At what weeks?
oral glucose tolerance test at 24 - 28 wks
Earlier screening if high suspicion/concern of…
- Prior gestational DM
- Strong FHx of gestational DM
- Prior delivery of baby weighing > 4000 g (8.8 lbs)
- A1C > 5.6
- Obesity (BMI >30)
- Known dyslipidemia
What is the screening test done for gestational DM?
Oral glucose tolerance test
What are the types of oral glucose tolerance test?
1 step or 2 step
Describe the 2 step oral glucose tolerance test.
- Step 1 - 50 g 1hr screening test; if (+), 2nd step is done
- Step 2 - Fasting 100 g 3hr tolerance test; if abnl at 2 checkpoints, dx of gestational GM is made
Describe the 1 step oral glucose tolerance test.
Fasting 75 g 2hr tolerance test; if abnl at 2 checkpoints, dx of gestational DM is made
What is fetal monitoring used for?
to monitor fetal health & development when there is concern for premature demise
Indications/concerns for premature demise?
- advanced age
- decr fetal activity
- maternal HTN
- multiple fetuses
- Oligo/polyhydramnios
- Premature rupture of membranes
- Prior fetal demise
- Post-term preg (>40wks)
- SLE, SCA, or Rh (-) mother
What are the types of fetal monitoring?
- HR monitoring
–> Antepartum or Intrapartum - Biophysical profile (BPP)
What are the 2 types of antepartum fetal monitoring?
- Non Stress test (NST)
- Contraction Stress Test (CST)
What is normal fetal HR?
120 - 160
What causes accelerations & are they good or bad?
due to changes in position, stimulation
- GOOD; baby is moving
What causes decelerations & are they good or bad?
may be due to hypoxia from cord compression, umbilical cord strangulation or acidemia
- BAD; assoc. w/ contractions
How long is a NST?
20 mins of external HR monitoring
Possible grades for a NST
reactive or nonreactive
What criteria needs to be met to be a normal reactive test?
At least 2 episodes of incr HR that meets criteria:
10-15 bpm above baseline & lasting at least 10-15 secs
Does a NST have to take the entire 20 mins?
No, can end the test early if test is normal
What are abnl results of a NST
- nonreactive
- doesn’t meet criteria for normal test at 20 mins
What can be done if the normal criteria for a NST isn’t met in the 20 mins for a NST?
- can extend to 40mins or repeat after 30mins
- Can try fetal stimulation & retest
You NST is extended, what happens next?
FU testing - US
What is a CST?
contractions are induced via oxytocin or nipple stimulation
What makes a normal CST?
see 3+ contractions w/n 10 mins
When does fetal HR usually decelerate?
at the start of a contraction
Late deceleration is a sign of…
hypoxia
How is CST graded?
- positive or negative
AND - reactive or nonreactive
What are the possible results of a CST?
DONE
Dx tool used for a BPP
Ultrasound
What are the 4 parameter of a BPP?
- fetal movement
- fetal tone
- fetal breathing
- amniotic fluid volume
What is the 5th parameter of a BPP?
non stress test
How long is a BPP?
30 mins but points can be assigned at any time
Each parameter for a BPP can be scored as…
0 or 2
What are the specific criteria points for a BPP?
- Fetal movement – at least 3 discrete body or limb movements
- Fetal tone – at least 1 extension of limb or spine w/ return to flexion
- Fetal breathing – at least 1 episode of rhythmic breathing lasting at least 30 sec.
- Amniotic fluid volume – at least one 2 cm x 1 cm pocket of fluid noted
What are the possible interstation of a BPP?
- 8/8 or 10/10 – very low risk of fetal death w/n 1 wk
- 4/10 or less – consider emergent delivery
- 8/10 – very low risk as long as amniotic fluid vol was +2
- 6/10 but +2 amniotic fluid vol = equivocal. Repeat BPP in 24 hrs.
6/10 or 8/10 and +0 amniotic fluid vol – concerning – weigh risks/benefits of cont preg vs emerg delivery
What are the types of intrapartum HR monitoring & examples?
External monitoring
–> doppler
–> fetal stethoscope
Internal monitoring
–> fetal scalp electrode
Describe a Category I on intrapartum fetal monitoring
- normal
- HR 120-160
- Some variability of HR
- No late / variable decelerations
Describe a Category II on intrapartum fetal monitoring
- watchful waiting
- Not Cat I, but doesn’t meet criteria for Cat III
Describe a Category III on intrapartum fetal monitoring
- VERY WORRISOME
- No variability of HR AND
–> Sustained bradycardia OR
Recurrent late or variable decelerations
–> Sinusoidal pattern
What has be done if you see a Cat III on intrapartum fetal monitoring?
C-section
How many weeks is considered preterm labor?
<37 weeks
Diagnostics for preterm labor?
- Visual Exam
- Digital cervical exam
- Transvag US
- Transabdo US
- Presence of contractions
What are you looking for on visual examination?
assess bleeding & membrane rupture
What are you looking for on digital cervical exam?
assess cervical dilation & effacement
What are you looking for on Transvag US?
assess cervix length
What are you looking for on Transabdo US?
assess amniotic fluid vol, fetal position, etc.
What labs should be done for preterm labor?
- Group B Strep
- UA & Urine culture
- Fetal fibronectin
What can Group B strep lead to?
neonatal meningitis
Describe a fibronectin test?
- via vag swab
- only found in ammonitic fluid
What information does a fetal fibronectin lab tell us?
presence increases chances of labor within 1 wk.
When is fetal fibronectin likely more useful?
<34 wks gestation & < 3cm dilation
How is the diagnosis of preterm labor made?
Presence of contractions PLUS
- Cervical dilation >/= 3cm OR
- Cervix length < 20 mm OR
- Cervix length 20-30 mm & (+) fetal fibronectin test
Diagnostics for Prelabor Rupture of Membranes
- visual examination
- Transadbo US
- Presence IGF binding PRO or placental alpha microglobulin-1 in vaginal fluid
What are the two older test done to assess for amniotic fluid?
- Nitrazine pH test
- Fern Test
What is the normal pH of vaginal secretions?
4.5 - 5.5
What is the normal pH of amniotic fluid?
7.0 - 7.5
What will a fern test show if amniotic fluid is present?
will dry in fernlike pattern due to NaCl, PROs & CHO fluid
What diagnostics are associated w/ labor?
fetal monitoring & labs
What are we looking for on fetal monitoring during labor?
Category I - III & monitor HR
What labs should be done during labor, if not already done?
- Group B strep
- Syphilis
- Hep B
- HIV
- type & screen or type & crossmatch
