45. US examination during pregnancy

Question 1

when is ZERO US performed?

Answer 1

5-6

weeks

Question 2

what are the goals for ‘Zero US’?

Answer 2

1. Confirm intrauterine pregnancy, exclude extrauterine implantation
2. Assess heart rate (first sign at 6 weeks)
3. Crown-rump length (CRL) to assess gestational age; adjust the expected due date to Naegele’s rule estimation

Question 3

what are the goals for ‘Genetic I US’?

Answer 3

1. Down syndrome screening:
   
   1. Nuchal translucency (NT): normal < 3.2 mm
   2. Nasal bone
   3. Tricuspid insufficiency
   4. Umbilical vein flow (reversed flow is abnormal)
2. Crown-rump length (CRL) to assess gestational age; adjust the expected due date to Naegele’s rule estimation
3. Assess fetal heart
4. Fetal urinary bladder: megacystis as an early sign of chromosomal anomaly

Question 4

normal Nuchal translucency (NT)

Answer 4

<3.2 mm

Question 5

at what week is the ‘Genetic I US’ performed?

Answer 5

11-13 weeks

Question 6

what week is the ‘genetic II US’ performed?

Answer 6

18-22 weeks

Question 7

what week is the ‘genetic II US’ performed?

Answer 7

18-22 weeks

Question 8

what is performed in ‘genetic II US’?

Answer 8

1. Biometry:
   
   1. Biparietal diameter, bitemporal diameter, occipitofrontal diameter, head circumference
   2. Abdominal circumference
   3. Femur length
2. Examination of fetal heart:
   
   1. 4-chamber view
   2. Outflow tract view (tetralogy of Fallot, TGA)
3. Amniotic fluid volume (AFI, single deepest pocket)
4. Placenta: normal implantation and growth
5. Assess normal organ growth and development, exclude malformations (diaphragmatic herniation, esophageal atresia, multicystic kidney, omphalocele, gastroschisis, neural tube defect, limb malformation)

Question 9

what is done during measurement US in 30-32 weeks?

Answer 9

1. Check fetal well-being and exclude IUGR
2. Doppler examination:
   
   1. Umbilical artery (absent/reverse blood flow, early diastolic notch)
   2. Uterine artery
   3. Middle cerebral artery (MCA): ↑ flow may indicate fetal anemia
   4. Resistance index (RI): umbilical artery vs. MCA (blood centralization)
      
      • Abnormal finding when umbilical artery RI > MCA RI
3. Fetal position
4. Biometry
5. Placenta: normal implantation, growth, and circulation
6. Amniotic fluid volume measurement

Question 10

what is the depth and AFI in Oligohydramnios?

Answer 10

Depth <2cm
AFI ≤5 cm

normal:
depth: ≥ 2 and < 8 cm
AFI: > 5 cm and < 24 cm

Question 11

What are the depth and AFI values in Polyhydramnios?

Answer 11

depth: ≥ 8 cm
AFI: ≥ 24 cm

normal:
depth: ≥ 2 and < 8 cm
AFI: > 5 cm and < 24 cm