Ultrasound Evaluation During the First Trimester of Pregnancy

Ultrasound Evaluation During the First Trimester of Pregnancy W Bruce Clark, M.D...  Vaginal ultrasound is usually superior to abdominal scanning Resolution is superior because  The t

Ultrasound Evaluation During the First

Trimester of Pregnancy

W Bruce Clark, M.D

 Vaginal ultrasound is usually superior to abdominal scanning

 Resolution is superior because

 The transducer tip is closer to the pregnancy

 This allows a higher frequency transducer

 The exception being nuchal translucency

 More freedom of movement on the anterior abdominal wall

Gestational Sac

 First ultrasound sign of pregnancy

 At 4 weeks 1 day to 4 weeks 2 days 2-3 mm

 At 5 weeks 5mm, can be seen abdominally

 Beware of the pseudo sac

5 week sac

Yolk Sac

 Transvaginal

 Appears at 5 to 5.5 weeks

 Mean Sac Diameter (MSD) 5mm to 8mm

Pseudo Sac

6 week with yolk sac

First Trimester

 Gestational Age

 Best predicted by the Crown Rump Measurement

Signs of First Trimester Pregnancy

Failure

 Sac with no embryo

 Embryo ≥ 4 mm with no FH

 Small sac size

 First trimester bradycardia

 Yolk sac too big, irregular, or calcified

 Slow embryo growth

Ultrasound Findings of an Abnormal

Sac

 MSD >8 mm without yolk sac

 MSD > 16 mm without embryo

Using HCG values to evaluate abnormalities of pregnancy

 Blood 5µ/ ml ~ 3 or 4 days

 Urine 50µ/ ml ~ 10 days

 Ultrasound 1,000-1,500µ/ml ~18 – 20 days

(gestational sac)

First trimester fetal abnormalities

 Fetal Abnormalities

 Nuchal translucency

ULTRASOUND IN PRIVATE

PRACTICE

W Bruce Clark, M.D

First Trimester

 Gestational Age

 Crown Rump Measurement

First Trimester Ultrasound

Signs of First Trimester Pregnancy

Failure

 Sac with no embryo

 Embryo ≥ 4 mm with no FH

 Small sac size

 First trimester bradycardia

 Yolk sac too big, irregular, or calcified

 Slow embryo growth

Ultrasound Findings of an Abnormal

Sac

 MSD >8 mm without yolk sac

 MSD > 16 mm without embryo

Ectopic Pregnancy

Diagnosis of Pregnancy

 Blood 5µ/ ml ~ 3 or 4 days

 Urine 50µ/ ml ~ 10 days

 Ultrasound 1,000-1,500µ/ml ~18 – 20 days

(gestational sac)

First trimester fetal abnormalities

 Fetal Abnormalities

 Nuchal translucency

Second trimester fetal

abnormalities

 Anatomical

 Chromosomal

Markers for chromosomal

Third trimester fetal well being

 Growth

 Doppler flow of umbilical arteries

 Amniotic fluid volume

 Placental grade

 Fetal breathing movements