Imaging in pregnancy

Question 1

Initial modality of choice for suspected appendicitis

Answer 1

Ultrasonography

Question 2

2nd choice modality for suspected appendicitis

Answer 2

MRI or CT

Question 3

Initial modality of choice for suspected PE

Answer 3

CT

Question 4

Initial modality of choice for renal colic

Answer 4

Ultrasonography

Question 5

Initial modality of choice for trauma

Answer 5

US, but CT if serious injury suspected

Question 6

Is it safe to continue breastfeeding after iodinated contrast?

Answer 6

Yes

Question 7

Is it safe to continue breastfeeding after gadolinium?

Answer 7

Yes

Question 8

Risk of of SAB with CT

Answer 8

Within 1st 2 weeks of embryonic age, there is a risk of failure of blastocyst to implant when irradiation dose is > 10 rads, but likely no increased risk if embryo survives

Question 9

When is the fetus most susceptible to teratogenic effects of ionizing radiation?

Answer 9

Btw 2nd and 20th week of embryonic age

Question 10

What are the teratogenic effects of ionizing radiation?

Answer 10

Microcephaly, microphthalmia, mental retardation, growth restriction, behavior defects, cataracts

Question 11

Estimated threshold radiation dose below which no teratogenic effects occur

Answer 11

Not exactly knonw, but btw 5 & 15 rads

Question 12

Radiation dose to fetus from CT pelvis

Answer 12

Ranges from 2.4 rad in 1st trimester to 4.6 rad in 3rd trimester
Other articles quote 1-4.5 rad

Question 13

Baseline risk of fatal childhood cancer, RR after exposure to 5 rads

Answer 13

Baseline = 1/2000
Relative risk = 2

Question 14

Radiation dose to fetus from abdominal xray

Answer 14

0.1-0.3 rads

Question 15

Radiation dose to fetus from IVP

Answer 15

0.6 rads

Question 16

Radiation dose to fetus from barium enema

Answer 16

0.7 rads

Question 17

Radiation dose to fetus from lumbar spine x-ray

Answer 17

0.6 rads

Question 18

Intraamniotic iodine contrast vs IV

Answer 18

Intraamniotic - potential to produce neonatal hypothyroidism
IV - reported to have no effect on neonatal thyroid fxn

Question 19

Is there a risk of acoustic injury to the fetus during prenatal MRI?

Answer 19

Follow up studies of children exposed to prenatal MRI suggest that acoustic damage during pregnancy is more of a theoretical than real concern - Chen 2008

Question 20

Why should gadolinium only be used if absolutely essential?

Answer 20

Gadolinium crosses the placenta, where it is pre-sumably excreted by the fetal kid-neys into the amniotic fluid. In the era of gadolinium-induced nephro-genic systemic fibrosis, this raises theoretical concerns of toxicity re-lated to disassociation and persis-tence of free gadolinium

Question 21

How often will US correctly visualize obstructive urinary calculi?

Answer 21

Approximately 60% of the time.

Question 22

Source

Answer 22

Chen, et al 2008