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OB > radiology in OB > Flashcards

radiology in OB Flashcards

1
Q

safety of x-rays depends on what?

A

“all-or-none” phenomenon
location of irradiation
amt of radiation
timing (during pregnancy) of exposure

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2
Q

harmful effects of ionizing radiation

A

cell death & teratogenicity
carcinogenesis
genetic effects or mutations in germ cells

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3
Q

high dose radiation 5.5-6 days after ovulation, before implantation

A

spontaneous abortion

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4
Q

high dose radiation (>200 rad) effects after implantation

A

growth restriction
microcephaly
mental retardation

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5
Q

when does high dose radiation have the greatest effect

A

8-15 weeks

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6
Q

no proven effect of high dose radiation when

A

25 wks

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7
Q

risk of severe mental retardation occurs at what level of rads?

A

40% at 100 rad

60% at 150 rad

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8
Q

with doses < 5 rads, no increase in

A

fetal growth restriction
fetal anomalies
spontaneous abortion
-threshold may exist at 20-40 rad

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9
Q

genetic effects of radiation

A

may increase frequency of natural mutations, NOT create de novo mutations
no increased risk of genetic d/o’s has been noted in any human pop at any dose

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10
Q

MRI & pregnancy

A

magnets alter E state of H+
may be helpful in Dx of fetal CNS defects, IUGR, placenta accreta
some people advise against use in 1st trimester

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11
Q

nuclear medicine & pregnancy

A

“tagging” a chemical agent w/ radioisotope-fetal exposure depends on radioisotope’s physical & biochemical properties

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12
Q

Tc 99m nuclear medicine

A

used in brain, bone, renal, CV scans

exposure < 0.5 rads

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13
Q

VQ scans Tc 99m for

A

perfusion

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14
Q

VQ scan 127Xe or 133Xe for

A

ventilation

exposure ~ mrads (o.05 rads)

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15
Q

ULS in pregnancy

A

sound waves, not ionizing radiation
no reports of adverse fetal effects
FDA arbitratily limits E exposure to 94mW/cm2
no CI in pregnancy

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16
Q

indications for 1st trimester ULS

A 
confirming fetal viability
"dating" the pregnancy by crown-rump length
ruling out extrauterine pregnancy
diagnosing multifetal pregnancy
guidance for removal of IUD
r/o molar pregnancy
guidance for chorionic villous sampling
nuchal translucency testing
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17
Q

pregnancy dating

A 
accuracy of ULS varies by trimester
error of ULS
-1st trimester: 4 day- 1 wk
-2nd trimester: 10 days- 2 wks
-3rd trimester: 2-3 wks
assessment of fetal growth patterns linked to ULS error
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18
Q

ectopic pregnancy & ULS

A 
most ectopics are tubal
presentation: 7-8 wks
triad: pain, bleeding, +UPT
ULS cannot definitively r/o ectopic, but can rule in intrauterine pregnancy
less common sites: cornual, cervical
19
Q

pregnancy w/ IUD

A

miscarriage risk is 10% greater w/ IUD in situ

string may retract into cervix as uterus enlarges

20
Q

molar pregnancy & ULS

A

molar gestation-neoplactic placental growth
fetus present (partial) or absent (complete)
inheritance: uniparental disomy
Lab: high levels of hCG
Sx’s: hyperemesis, hyperthyroidism
ULS: “snowstorm” or “grape-like” clusters
high incidence of fetal CNS anomalies

21
Q

CVS & ULS

A

bx of placental tissue at 10-13 wks
Dx’s chromosomal or genetic d/o’s for which DNA testing is available
ULS guides needle/catheter into placental tissue

22
Q

fetal nuchal translucency- edema in the fetal neck

A

11.5 & 14.5 wks
abnormal edema assoc. w/ chromosomal & fetal structural abnormalities
-down syndrome (T21) detection rate: 80% w/ NT alone, 90% w/ assoc. biochemical markers
Assessment by absolute size (>3.5 mm) for structural defects. Gest age dependent nmls (2.2-2.8 mm) for chromosomal abnormalities

23
Q

2nd trimester ULS uses

A 
assessing gestational age
multifetal pregnancy detection
screening for fetal anomalies
placental localization & eval
amniotic fluid eval
guidance for amniocentesis
24
Q

components of a 2nd trimester ULS

A 
gestational age/ fetal growth
fetal position
fetal #
placental location
amniotic fluid vol.
uterine eval- fibroids, anomalies
cervical evaluation
fetal anatomy
25
Q

placenta on ULS

A 
where is it?
-anterior
-posterior
-fundal
-covering the cervical os
is it normal?
-molar pregnancy
-separated? abruptio placenta
26
Q

placenta previa

A

complete, partial or marginal
common in 2nd, rare in 3rd trimester
higher incidence in multipares, elderely, previous c-section or abortion
may detect retroplacental or retromembranous clot- abruptio placenta

27
Q

amniotic fluid assessment

A

increased= polyhydramnios

  • DM
  • upper GIT obstruction
  • chromosomal abnormalities
  • muscular lesions affecting swallowing
    decreased: oligohydramnios
  • rupture of the membranes
  • absent fetal renal tissue/ lower UT obstruction
  • intrautering growth restriction
28
Q

uterine eval w/ OB sonography

A 
overall shape & size
presence of anomalies
-uterus didelphys (including double cervix)
-uterine septa, bicornuate uterus
presence of tumor-leiomyoma
29
Q

cervical eval during 2nd trimester

A

nml cervical length: >2.5 cm
borderline area: 2.0-2.5 cm
abnormally short: membranes
placement of cervical cerclage

30
Q

fetal anatomic survey: “the level II ULS”

A

systemic survey for fetal anomalies

performed usually bet. 16-22 wks

31
Q

“the level II ULS” survey- what it looks at

A 
CNS
cardiopulmonary
GI
GU
MS
umbilical cord
fetal exterior
32
Q

CNS & spine

A

cerebral ventricles
posterior fossa & cerebellum
cavum septum pellucidum
cranium- encephalocele, hypo & hypertelorism
spina bifida- myelocele, myelomeningocele

33
Q

cardiopulmonary assessment

A

4 chamber hear, outflow tracts
echogenic foci
cardiac masses-myoxoma, rhabdomyoma
pulmonary evaluation-diaphragmatic herniation
-masses: cystic adenomatoid malformations (CCAM), bronchopulmonary sequestration
-effusions

34
Q

GI assessment

A

GI tract obstruction
-absence of ST “bubble”- tracheo-esophageal fistula
-“double bubble”- duodenal atresia
-anal atresia
Ascites
Echogenic bowel-brightness=bone brightness
-T21, CF, intrauterine bleeding, infxns (CMV, toxoplasmosis)

35
Q

GU assessment

A

nml anatomy- kidneys & bladder seen, ureters & urethra not seen
Abnormal: dilated renal pelvis-obstructive, “flaccid”
obstructions: UPJ, UVJ, urethral (bladder outlet), hydronephrosis
renal, ovarian cysts
hypospadias, penile anomalies
cystic renal changes

36
Q

umbilical cord assessment

A 
# of vessels- 2 vessel cord associated w/ chromosomal, skeletal, GU tract abnormalities
insertion site into abdomen- defects gastroschisis, omphalocele
37
Q

MS assessment

A

calvarium
long bones- presence/absence, length, bowing, fractures
digits- # & orientation
abnormalities: skeletal dysplasias, spondylolystheses, ichythyoses

38
Q

fetal exterior/integument assessment

A

craniofacial- cleft lip & palate, cystic hygroma

teratomas- sacrococcygeal

39
Q

3rd trimester assessment

A

fetal growth- biometry, fluid assessment: AFI
fetal well-being- biophysical profile, doppler studies
fetal pulmonary maturity studies-LBC, SA ratio, LS ratio, PG level

40
Q

Macrosomia: > 90th % for GA

A

often assoc. w/ DM
CPD/ shoulder dystocia
US widely used to est. fetal wt
C-section recommended for 4750 gm (non-diabetic), 4250 gm (diabetic)

41
Q

IUGR < 10th % for GA

A 
chromosomal abnormalities
renal dz & HTN
connective tissue dz- SLE
perinatal infxns- CMV, toxoplasmosis, etc
thrombophilia- clotting abnormalities
placental abnormalities
42
Q

fluid assessment

A

amniotic fluid vol. is an indicator of fetal renal output

decreased amniotic fluid is assoc. w/ increased rate of perinatal mortality

43
Q

biophysical profile

A 
excellent predictor of fetal well being
4 ULS parameters +NST
-fetal breathing
-fetal tone
-fetal mvnt
-amniotic fluid vol. (2 cm pocket)
2 pts for each nml parameter
nml:>/= 7 points

OB (13 decks)

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