Ultrasound diagnosis during gestation

Question 1

What are the types of ultrasounds used and their frequencies

Answer 1

Transvag: 6.5-7.5 MHz

Transabdominal: 3.5-5.0 MHz

Question 2

What are the numbered screenings and when do they occur?

Answer 2

0) The first prenatal visit. usually at about the 5th or 6th week, after the missed period. Transvaginal.
1) 11-13th week. (right at the end of first trimester) Transvaginal or Transabdominal.
2) 18-20th week. transabdominal.
3) 30-31st week.
4) 36-37th week.

Question 3

0 screening

Answer 3

To diagnose pregnancy, locate site of implantation, and fetal number.
5th week - can see gestational sac
6th week - can see the fetal pole
7-8th week - can hear fetal doppler heart tones.

Question 4

“1st” screening

Answer 4

11-13th week.

To measure CRL and determine correct gestational age, and evaluate for malformations or chromosome problems.

Also evaluates nasal bone, nuchal translucency, and ductus venosus flow.

Question 5

2nd screening

Answer 5

18-20th week.

To diagnose congenital malformations
- duodenal atresia, omphalocele, renal dysplasia, achondroplasia, airway malformations.

• evaluate site of placenta and possible abnormal placentation.

Question 6

3rd screening

Answer 6

30-31st week

To evaluate fetal size and compare to previous measurements, checking for IUGR vs SGA.

To evaluate amniotic fluid, placenta, blood supply, and late onset malformations such as corpus callosum agenesis.

Question 7

4th screening

Answer 7

36-37th week.

To recognize high risk populations and prepare for delivery.