WH Labs and Imaging Flashcards
Estrogen types
*Estrone (E1),Estradiol (E2), Estriol (E3)
* Majority is produced by the placenta
causes of Low levels of estrogen
- Possible problem w/ placenta
- Can indicate some birth defects such as Down Syndrome
- Difficulty w/ spontaneous labor if still low at term
Causes of high levels of estrogen
- Increased risk of premature labor if sudden spike before week 37
Progesterone functions
- Thickens uterine lining and prevents ovulation during pregnancy
- Produced by the corpus luteum and then by the placenta
- Should increase throughout pregnancy
Causes of low levels of progesterone
- Infertility, higher risk of preterm labor/miscarriage and
pre-eclampsia - Can signal ectopic pregnancy
Causes of high levels of progesterone
Multiples, molar pregnancy
Follicle Stimulating Hormone (FSH)
- Produced by the pituitary gland
- Stimulates estrogen production and maturation of follicles in the ovary
- Suppressed by high levels of estrogen/progesterone
- High levels (>25.8) = postmenopausal, infertility hypopituitarism
Luteinizing hormone (LH)
- Produced by the pituitary gland
- LH surge causes ovulation (so can be used to track ovulation)
- Stimulates the corpus luteum to produce progesterone (supports early
stages of pregnancy) - Low levels = postmenopausal, infertility, hypopituitarism
Prolactin
- Produced by pituitary gland
- Stimulates lactation
- Elevated in pregnant and breastfeeding women
Causes of Low levels of prolactin
Infertility, lack of milk production, not pregnant or breastfeeding, hypopituitarism
High levels of prolactin causes
pregnancy/breastfeeding, prolactinoma, antipsychotics
ABO incompatibility
- Often seen in firstborn infants (20%)
- Most group O women have developed anti-A and anti-B isoagglutinins
before pregnancy from exposure to bacteria - Rarely becomes progressive in future pregnancies
- Anti-A and anti-B antibodies are IgM
- Typically does not cause appreciable hemolysis in the fetus
- improved results since the 1950s
Rh antibody screen
- Indirect Coombs test to test for maternal alloimmunization
- IgG antibodies = Rh incompatibility = fetal hemolytic anemia
- Rh incompatibility is progressive, affects second and
subsequent pregnancies
What is the grandmother effect?
- It is possible for an Rh- female fetus exposed to maternal Rh+ red cells to develop
sensitization (while still in the womb) - Means she may produce anti-D(Rh) antibodies before she is even born, so 1st pregnancy
is already at risk - The fetus in the current pregnancy is jeopardized by maternal antibodies that were
initially provoked by his or her grandmother’s erythrocytes
Rubella screening
- Titer
- Negative results are < 7 IU/mL IgG and < 0.9 IgM antibodies
- Infection in the first trimester poses significant risk for abortion and severe congenital
malformations - Rubella vaccination should be avoided 1 month before or during pregnancy
Syphilis screening (RPR)
- Spirochetes cross the placenta to cause congenital infection, stillbirth
- Delivery
- Risk directly related to maternal spirochete load
- Treat ASAP after Dx
HIV Screening
- Checked also at a patient’s initial visit
- Can lead to AIDS
- Can pass to fetus
- If positive, medications used to protect the fetus during delivery, and to baby after birth
- Passed through breastmilk
Beta-HCG qualitative vs. quantitative testing
*Qualitative (You do this one at home)
*Detects the presence of HCG
*Urine
*Quantitative (β-hCG)
*Measures the amount present in
the blood
*Confirms pregnancy
*Doubles every 3 days and reach its
peak at 8-11 weeks of a normal
pregnancy
*US more accurate after 5-6 weeks
of gestation as this is more
accurate
Quad screen: Screening test components
*Alpha-fetoprotein (AFP), made by baby
*Β-hCG, made by placenta
*Estriol, made by placenta and fetus
*Inhibin-A, made by placenta
When is quad screening done and when should it be considered?
*Weeks 16-18
* Most accurate timing (can be done 15-22 wks)
*Consider if family history of birth defects, ≥ 35 years, diabetes with insulin, radiation exposure, viral infection during pregnancy, harmful medication or drugs use
Alpha-fetoprotein (AFP)
*Most common reason for elevated levels is
inaccurate dating of pregnancy
*High levels may indicate a neural tube
defect
*Low levels AFP with abnormal hCG, inhibin
A, and estriol may indicate Trisomy 21 or 18
Noninvasive prenatal testing (NIPT)
*Prenatal cell-free DNA (cfDNA)
*Screening blood test
*≥10 weeks
*Trisomy 21, trisomy 18, trisomy 13, fetal “Y” chromosome
Noninvasive prenatal testing (NIPT) process
*DNA from the mother and fetus is extracted from a maternal blood sample and screened for the increased chance for specific chromosome problems
*97 to 99% accuracy for negative predictive values
*Chorionic villus sampling (CVS) or amniocentesis to confirm
Oral Glucose Tolerance Test
OGTT
*50 grams
*1-hour glucose challenge (step 1)
*>140mg/dL is abnormal
*Diagnostic 3-hour oral glucose tolerance test (move to 3 hour if abnormal in 1 hour)
*Fasting: > 95 mg/dL
*1 hour: > 180 mg/dL
*2 hour: > 155 mg/dL
*3 hour: > 140 mg/dL
*If more than 1 is higher than
normal = gestational diabetes
Amniocentesis
Removal of amniotic fluid by a needle through the maternal abdomen with ultrasound guidance
Used to diagnose fetal chromosomal abnormalities or neural tube defects after an
abnormal screening test
Amniocentesis
Cordocentesis
*Percutaneous umbilical cord blood sampling
*Usually done after week 17/18
*Can detect anemia, chromosome abnormalities, infections,
blood disorders
*Can’t detect neural tube defects
Blood transfusions or medication can be given directly to the fetus through ______
the umbilical cord
Chorionic Villus Sampling (CVS)
- Chorionic villi have the same genetic
material as the baby - Transabdominal or transcervical
- Can be used to detect chromosome
abnormality or other genetic disorders - Can’t detect neural tube defects
- Miscarriage risk of 0.7%
- Limb defects (esp if done before 9 wks)
L/S Ratio
Lecithin–sphingomyelin ratio in amniotic fluid
* Surfactants
* Higher lecithin/sphingomyelin ratio = more mature lungs
* Test done 32-39 weeks if at risk of premature delivery
Ranges for L/S ratio
<1.5:1 = immature lungs
1.5:1 – 1.9:1 = risk for immature lungs
≥2.1:1 = mature lungs
Kleihauer-Betke (KB) Test
- Fetomaternal hemorrhage screening
- Quantifies the amount of fetal hemoglobin in
maternal circulation - Maternal trauma/placental disruption
- Additional RhoGAM given if mother RhD negative
Kleihauer-Betke (KB) Test process
- A peripheral blood smear is made from the maternal
sample and treated with acid. The slides are
washed, stained, and examined microscopically - The number of fetal cells are counted per number of
maternal cells to give % fetal cells - Cannot be detected if less than 5mL blood shared
Nitrazine Test process
*Premature rupture of membranes
(PROM)
*Prior to 37 weeks
*Place a drop of fluid obtained from the
vagina onto paper strips containing
Nitrazine dye
*The strips turn blue if the pH is greater
than 6.0
*A blue strip means it’s more likely the
membranes have ruptured
When allowed to dry,
amniotic fluid results in
a ______
fern pattern (ferning)
Obstetric Ultrasound
*Transvaginal or abdominal
*Initial US to confirm intrauterine
pregnancy
*Embryo can be observed at about
6 weeks
*Heartbeat visible 6-7 weeks
*If observed, probability of
continued pregnancy high
18-20 week scan
*Determine gestational age
* Crown-to-rump length
* Biparietal diameter
* Femur length
*Abdominal circumference
*Amount of amniotic fluid
*Placenta location
*Number of fetuses
*Malformations
Other indications for US
*Preterm labor
*PROM
*Vaginal bleeding
*Determine fetal presentation
*Decreased fetal movement
*Most offices do 1-2 during
1st trimester, one at 20
weeks, and then PRN to
assess.
Doppler US use in pregnancy
*10 weeks (can hear heartbeat)
*110-160 beats per minute on
average
What does an External fetal heart rate monitor do?
Heart rate and contractions
Internal fetal monitor indications for use
- Electrode wire on baby’s scalp
- Only used if amniotic sac is
ruptured and cervix is open - DON’T use in HIV+ moms
Hysterosalpingogram
- Fluoroscopy of the uterus and fallopian
tubes - Contrast injected through the cervix
- Most commonly used in the evaluation of
infertility
Group B Strep Testing importance
- GBS typically harmless in healthy adults, normal bacteria in
lower GI tract - Can cause serious illness in newborns
- pneumonia, meningitis, sepsis
● Test in the 3rd trimester at 36-37 weeks of
pregnancy
● Vaginal and Rectal swab
● If (+) then Abx treatment during labor (penicillin)
