1. lec. 1 U/S Dr. Lina Hammad Level 9
Obstetric sonography
lec. 1 U/S
Dr. Lina Hammad
Level 9

2. Obstetric sonogaphy is usually obtained twice during normal pregnancy
calculated from LMP
weeks. (1st scan in 2nd trimester)
32 – 36 weeks. (2nd scan in 3rd trimester)

3. Indication for 1st scan (18-22week)
Measurement of gastational age.
Diagnose multiple pregnancy.
Diagnose fetal abnormality.
Locate placenta
Recognize pelvic masses that will interfere with the pregnancy myomas.

4. Indication for 2nd scan (32 - 36week)
Diagnose intrauterine growth retardation.
Diagnose fetal abnormality.
Confirm the presentation and position of the fetus.
Locate the placenta more accurately.
Assess the amount of amniotic fluid.
Exclude complication.

5. Indication for an early (pre 18 weeks) ultrasound
To confirm pregnancy and it’s location (intra / extrauterine)
Estimation of gestational age.
To identify multiple pregnancies.
Exclude molar pregnancy.
Exclude pseudo-pregnancy.
To diagnose pelvic masses.

6. 1st trimester scaning
Afetus between weeks of age for nuchal translucency measurement .

7. Normal early pregnancy (18 weeks)
Gestational sac.
The embryo.
Yolk sac.
Corpus luteum
Multiple pregnancy.
IUCD

8. Gestational sac
Ahypoechogenic sac surrounded by double echogenic ring.
Seen at 5-6 weeks of pregnancy
Estimation of gestational age from G.sac volume is done.

9. The embryo Visible at 8 week.
(Echogenic area within the G.sac With cardiac motion).
Movement of the embryo and fetal head is observed seen >9-10 week
The skull is visible from 12 week.

10. Yolk sac Occasionally seen 7-11 weeks.
Around cystic structure adjacent to the fetus.
4-5mmø
Intrauterine pregnancy at 8 weeks' gestation, demonstrating embryo (E) and yolk sac (YS).

11. Corpus luteum Can be seen until 12th week up to 4 cmø
can rupture causing hemorrhages

12. Multiple pregnancy Can be seen at 8 weeks
Have to be confirmed after 14 weeks.
(18 – 22 weeks) as not all G.sac contains viable embryo.

13. IUCD Locate the IUD location, if inside the uterus:
IUD well away from G.sac. (no interferance)
IUD string is seen in vagina. (IUD will be removed)
Abortion might occur especially if IUD is near to implantation site.