USS Flashcards
USS landmarks in a 1st trimester pregnancy: (how many weeks do you see each? and when would each always be seen)
- Gestational sac seen
- Yolk sac
- Fetal pole
- Heart motion
- GS: 4 weeks +3 days
- 5/40. Always seen when MSD>10mm
- Around 6/40. Always seen when MSD>25mm
- Always when CRL> 7mm, nearly always seen when CRL visible
What is the rate of growth of fetal pole/yolk sac when 5-7 weeks?
1mm/day
Difference between gestational sac and pseudosac
GS: Eccentrically implanted on 1 side of endometrium, double decidual sign. Yolk sac presence confirms it’s a GS.
Pseudosac: midline fluid space which may move or disperse during examination
USS features at:
- 5 weeks
- 6 weeks
- 7 weeks
- 5 weeks: Gestational sac +/- yolk sac
- 6 weeks: Fetal pole +/- HB
- 7 weeks: Amnion encircles the fetus. Yolk sac outside the amnion.
Determining features of miscarriage:
- Early pregnancy loss
- Incomplete miscarriage
- Early pregnancy loss: MSD>25mm with no live fetus OR CRL>7mm with no HB.
- Incomplete miscarriage: Heterogenous tissue within cavity >15mm
- Complete miscarriage: Heterogenous tiisue/nil in cavity <15mm
Distinguishing features of an ectopic pregnancy
Associated features
- empty uterus - appearance variable, may have pseudosac
- ectopic mass- may be a ‘donut’ or adnexal ring
- A corpus luteum (maintains pregnancy at 7-9 weeks)
Associated features:
- may have echogenic free fluid (e.g. haemoperitoneum)
- ectopic mass may be a complex mass
Appearances of corpus luteum
Mean diameter 19mm (range 8 to 55mm)
Peripheral ring of vascularity (more than EP)
Can appear as solid mass*(most common)/thick walled cyst with anechoic centre/cyst with internal echoes (haemorrhagic)/thin walled simple cyst
With transvaginal ultrasound, normal early intrauterine gestation sac is visible in the uterine cavity before 6 weeks gestation. Which of the following features are normal?
Select one:
a. The sac is eccentrically positioned in the decidua
b. The midline decidual echo disappears
c. The sac is anechoic but is always surrounded by an echogenic trophoblastic ring.
d. The sac is visible from 3 weeks 4 days gestation
A
A woman presents to her nearest early pregnancy assessment service with a positive pregnancy test but no gestational sac seen in her uterus which has a thin endometrium on transvaginal ultrasound. No adnexal mass is seen. The most frequent outcome for the pregnancy in this situation is:
Select one:
a. An ectopic pregnancy.
b. A miscarriage.
c. A viable intrauterine pregnancy.
d. Spontaneous resolution with location unknown
D
A woman presents to you with vaginal bleeding and a positive pregnancy test. You perform a transvaginal scan. Which of the following findings enables you to make a conclusive diagnosis of an early pregnancy loss?
Select one:
a. A gestation sac with a MSD of 15mm and no fetal pole.
b. A gestation sac with a MSD of 20mm and no fetal pole.
c. A gestation sac with a mean sac diameter (MSD) of 10 mm and no fetal pole
d. A gestation sac with a MSD of 25mm and no fetal pole.
D
In the intrauterine image below, no cardiac activity is demonstrated in the fetal pole which has a CRL of 6mm. What is the diagnosis?
Select one:
a. Uncertain viability
b. Normal intrauterine pregnancy
c. Early pregnancy loss
d. Missed miscarriage
A
A woman presents at 7 weeks gestation with pain and vaginal spotting. What features on ultrasound are required to make a definitive diagnosis of an ectopic pregnancy.
Select one:
a. An “empty uterus” and a corpus luteum.
b. An “empty uterus”, an adnexal mass, a corpus luteum and free fluid in the Pouch of Douglas
c. An “empty uterus” and an adnexal mass.
d. An “empty uterus”, an adnexal mass and a corpus luteum.
D
Definitive diagnosis of a monochorionic diamniotic twin pregnancy by ultrasound during the first trimester is made by observing:
Select one:
a. That both fetuses are the same sex
b. A single placental mass
c. A Lambda sign at the junction of the membrane and placenta
d. A T-sign at the junction of the membrane and placenta
D
You perform a transvaginal scan in a woman with pelvic pain at 6 weeks gestation and detect a single live intrauterine fetus consistent with dates and a 25mm left adnexal mass. What features seen on your ultrasound examination would enable you to make a definitive diagnosis that the adnexal mass was a physiological corpus luteum?
Select one:
a. The mass is located in the left ovary and has the appearance of a thick-walled cyst with an anechoic centre
b. The mass is located in the left ovary which contains other smaller cystic structures consistent with follicles
c. The mass is located in the left ovary and has the appearance of a round hypoechoic structure
d. The mass is located in the left ovary and surrounded by a peripheral vascular ring visible with colour Doppler imaging
D
