MOD 3 Flashcards
What is the MoM?
measure of how far an individual result deviates from the median, used to report results of medical screning tests esp if indiv tests are highly variable (avoids multiple reference ranges), such as AFP
What is B-hCG, and what is it generally a marker for?
a hormone produced by trophoblasts of dev placenta 9 days after ovulation, good early marker for preg
What other conditions besides pregnancy can bHCG be used to evaaluate?
ectopic preg
spont abortion
gestational tumor
What does postiive bHCG indicate
Preg!
OR non-invasive molar tumors
OR testicular cancer
When does hyperglycosylated bHCG appear?
implantation phase of preg at a few weeks, and prevents CL regression and allows continued estro/prog synth
-major form of bHCG in choriocarcinoma
Free bHCG?
Nicked BHCG?
free- marker for DOWNS
nicked- present after removal of hydatiform mole
What might it mean if bhCG levels off early?
may indicate that preg is in trouble
What are some thigns that can produce false positive on b-hCG preg tests?
- hbcg-producing tumors
- pts that have heterophilic ab’s against mouse ab’s used in test
- have bhcg like material but usually too low for + result
- urine tests and renal failure can give incorrect results
Spontaneous abortions, and what they show with bhcg levels
first trim, v common
slowing in the rate of hcg incr means impending abortion, and drops during abortion
what is ultrasound used for in preg
not always that helpful, but helps estimate gest age, ID cause of vag bleeding, uterine size, confirms preg, or ectopic preg etc
Ectopic preg
timing
hcg levels
sx
common, usu in fallopian tube, sx start 4-6 wk after conception
- bhcg increase then level off, then the rate of increase slows
- sx: abnormal uterine bleeding, decreased hct, shock (can cause death)
Gestational tumors- Hydatidiform mole
HCG levels
HPL levels
trophoblastic dis where non viable fert egg is implanted, needs to be removed, produces v high levels of hCG and decreased HPL (hcg should decr a few months after removal, but if still there, may be residual mole or choriocarcinoma)
What is amniocentesis for?
chrom analysis (excludes Downs) or abnormal AFP follow up (can exclude spina bifida)
Chorionic villi sampling- what is it for? Adv? Disadv?
- collects cell from placenta villi to test genetic makeup of fetus
- ADV: QUICKER results (a week) than amniocentesis
- DISADV: RISK for miscarraige over amniocentesis, and chance of placental mosacisism (placenta has weird chroms but fetus is actually normal)
What are common prenatal tests?
Triple test
Prenatal US
What is the triple test?
-what is it used with? what does it test for?
prenatal test that tests maternal serum AFP, hCG, and UE3 (estriol) in the second trimester to screen for DOWNS and open NTDs at 16-18wk gest, 70% sens with 5% false +
-used in conjuction with prenatal ultrasound for gest age and fetal abnormalities and nuchal translucency or guiding needle placement etc
What might high AFP on triple test but low other vals mean?
NTD!
(spina bifidia if aceytlcholinesterase in amnio fluid)
or omphalocele, gastoschisis, multiple gest
What does high hCG but low other vals mean on triple test?
DOWN!
What does all low vals mean on triple test?
Trisomy 18! (edwards)
What does incr vs decr AFP indicate
incr- open NTD
decr- down, tirsomy 18, T1DM, endocrine pseudopreg