OB Diagnostic Imaging, procedures & Documentation Flashcards
Uses of the US in the first trimester
First Trimester: 1-12 weeks
- establish prescence or abscene of interuterine gestational sac & viability
- ecotpic pregnancy or other complications
- bleeding work up
- dating of pregnnacy: CRL: most accurate time to estimate date
use of US in second trimester pregnancy
Second Trimester: 13- 28 weeks
- due date confirmatino (can be off by +/- 2 weeks)
- Anatomy Scan at 18-22 weeks
- anomalites/amniocentesis
- multiples
- placental location
use of US in third trimester
Third Trimester: 29-40 weeks
- growth scan monitoring
- bleeding (abruption of placenta)
- BPP
- amniocentesis
US can also be used at any point in pregnancy to establish and evalulate growth scans for mothers with chronic disease which could impact fetus
First Trimesters US Scans
- development milestones
Determine presence of the Gestational Sac
- implantation in to the uterus
- careful not to confuse with corpus luteum cyst, which may have blood flow surrounding it too
Development
- 4 1/2 - 5 weeks: appearance of gestational sac
- 5-51/2 weeks: yolk sac apparent
- 6 weeks: embryo seen; fetal cardiac puslations
- 6.7-7 weeks: amniotic membrane appears
- 7-8 weeks: fetal spine appears
- 8 weeks: head & limbs distinct separation from torso
- 8-8 1/2 weeks: fetal motion can be felt
- 8-10 weeks: rhombencephalon
First Trimesters US Scans
- CRL and growth measurements
CRL: crown-rump-length
- the most accurate way to validate gestational age is to measure CRL and date gestation via US
measured
- from the crown of the head to the rump, or base of spine
generally
5 mm = 6 weeks
10 mm = 7 weeks
16mm = 8 weeks
22 mm = 8.8 weeks
First Trimesters US Scans
- type of US done
- US findings to indicate a viable preganancy
first trimester US must be done via TVUS since a pelvic will not reach deep enough
- any vaginal bleeding, cramping, pain or spotting warrents a TVUS in first trimester
Viable Pregnancy
- progressive increase in fetal HR from 1 US to next (like a week later)
- interuterine gestation confirmed iwth embryo and yolk-sace (CRL measured)
- evidence of growth via increasing CRL and increased fetal HR and evidence the cervix remains closed = viable pregnancy and location of the embryo in the uterus
First Trimesters US Scans
findings or suspicious of a pregnancy faillure
what would you find
Absent fetal cardiac activity
- if no HR by the time CRL is > 7mm = dx. of pregnancy failure
- if CRL is < 7 mm, suspcious but not a dx.
Absent Embryo
- if no embryo by the time the mean sac diamter is > 25mm = dx. of pregnancy failure
- if no embryo in two seperate US checks; even if found gestaional sac and yolk sac
Abnormal morphology of the gestaional sac, amnion or yolk sac
First Trimesters US Scans
Spontanous Abortion Signs
Spontaneous Abortion on US
- cramping & spotting = signs in first trimester
US evidence
- evidence of interuterine gestiation
- without HR
- movement of the gestational sac into the cervical canal & opening of cervix = indicates spontaneous abortion
First Trimesters US Scans
Subcorionic Hemorrhage on US
US First trimester: Subcorionic hemorrhage
- a collection of blood/fluid behind the placenta and where it attaches to the uterine wall (darker space behind the gestational sac)
can still have a viable and healthy pregnancy: just need to monitor more frequently
be suspicous for this if pt. presents with vaginal bleeding in first trimester
First Trimesters US Scans
Ectopic Pregnancy
Ectopic Pregnancy
assume abd. pain in any women of reproductive age is ecoptic until proven otherwise
presenting: cramping, pain, bleeding, etc. with + bHCG
US Findings
- the uterus will be EMPTY: nothing inside
- so you look to the adenxa: and you see the gestaional sac implanted in the adenax, ovary, etc. with fetal HR
- or you can look into the cervix: and see the gestational sac in there
First Trimesters US Scans
Gestational Trophoblastic Disease
US appearance
symptoms, dx and tx.
GTD: gestational Trophoblasic disease
- from the placenta: complete or partial hydatidiform moles can form
- benign or malignant
- hydatiform mole: empy egg or grape-like clusters or snowstorm pattern on US
- partial: part mole and part embryo, but often non-viable
- complete: all mole no viable pregnancy : higher risk of developing to a malignancy
Symptoms
- abnormal vaginal bleeding
- uterine size larger than date of pregnancy
- hyperemesis
- preeclampsia before 20 weeks
Dx.
- bHCG > 100,00 (marked elevation) persistanlty
- evidence of mole on US
First Trimesters US Scans
GTD
treatment for benign and malignantt
GTD
Benign
- complete or partial
- low risk: chemo
metastait
- chemo + radiation + surgery
- D&C to perserve fertility or TAH
serial bHCG monitoring: until baseline level achieved and then need to have contraception for 6-12 months after until total remission
First Trimesters US Scans
Reasons for vaginal bleeding
subchorionic hemorrage (MC)
implantation bleeding
threatened abortion
spontaneous abortion
all of these warrent a TVUS in the first trimester
Genetic/Aneuplodiy Screening in the First Trimester
First Trimester
Nuchal Translucency test: measures the nuchal space at the back of babies neck between 11-13 weeks “8-12wk scan”
Labs: get free BHcG + PAPP-A levels
if labs + and nuchal translucecny thickened ( >6mm) = high sensitivity for trisomy 21 but not 100%
a thickened nuchal tranlucency withOUT the labs = thick skeletal or cardiac abnormalities
Genetic/Aneuplodiy Screening : Second Trimester Screening
Quad Screen: four materal blood substances
Done between 15-22 weeks
these labs values + maternal age, weight, ethnicity, DM status and gestational age = estimate risk for trisomy 21 and 18
Values
MSAFP
BHcG
Estriol
Inhibin-A
Trisomy 18: all four levels will be decreased
Trisomy 21: BHcg + inhibin A elevated, MSAFP and estriol decreased
Trisomy 13: decreased bhcg and normal or elevated MSAFP
Screening results
- if women screens postive: there is a risk of these abnormalities, not 100%
- if this screen test is positive = move onto a detialed anatomy US
Postive Screening on second trimester Quad Screen
potential findings on teh anatomy screen which could clue you into….
Trisomy 21
Trisomny 21: anatomy scan findings
- brachecephaly
- broad nasal ridge
- low set ears
- oblique palpebral fissure
- simean creased
- cardiac (AV defects)
- duodenal atresia
- mental retadation
Postive Screening on second trimester Quad Screen
potential findings on teh anatomy screen which could clue you into….
Trisomy 18
Trisomy 18 (Edwards)
- pectus carinatum (outward)
- cardiac defects
- renal anomalies
- omphalocele
- overlapping fingers
- rockerbottom feet
- polyhydraminos
- small placenta
Postive Screening on second trimester Quad Screen
potential findings on teh anatomy screen which could clue you into….
Trisomy 13
Trisomy 13 (Patua’s Syndrome)
- holoproscencepahly (single brain lobe)
- clefting
- eye anomalies
- cardaic defects
- polydactaly
- rockerbottom feet
2nd Trimester US Scans
what scans are done
Anatomy Scan
lots of the 2nd trimester screens can be done in the 3rd as well
2nd trimester scans include
- anatomy scan
- due date confirmation
- anamolies/abnormalities
- placental location
- mutiples
Anatomy Scan
- done at the 18-22 week time frame
- measurements done here too (confirm due date)
Anatomy Scan
Fetal Head Scans: measurements where
Fetal Head Scan
- measurement at the level of the thalmus, not the cerebellum!!
what are you measureing
Biparietal Diameter (BPD)
- measure from teh otuside edge of one side to the inside edge of the other side
- also helps measures weight
Head Circumference
- assists with dating
