This document summarizes key aspects of an ultrasound scan in the first trimester of pregnancy. It discusses how pregnancy is detected, the role of ultrasound in confirming location and growth, and evaluating complications. Transabdominal and transvaginal ultrasound are complementary, with transvaginal allowing better detail. A normal gestational sac appears rounded with a thick echogenic rim. Potential problems addressed include miscarriage, ectopic pregnancy, gestational trophoblastic disease, and nuchal translucency measurement. Criteria for diagnosing miscarriage and definitive pregnancy failure are provided.

2. FIRST TRIMESTER OBS SCAN
Dr. Kazim
Resident Radiology
2

3. General consideration
 How pregnancy is detected
 Urine pregnancy test
 Blood test(beta hCG)
 Role of ultrasound
 Confirm intrauterine pregnancy
 Follow up the growth of pregnancy
 Evaluate complications
 Diagnose ectopic pregnancy and other pathologies

4. General considerations
 Transabdominal and transvaginal US have complementary role ; TVS
can show structures in more detail
 First sonographic finding in pregnancy is visualization of the GS
 A normal GS is rounded, with a thick echogenic rim around(double
decidual sac sign)

5. 5

6. 6

7. 7

8. 8

9. 9

10. 10

11. 11

12. 12

13. 13

14. 14

15. 15

16. 16

17. Definitive diagnostic criteria for IUP failure
Size based criteria;
1)CRL>7mm without cardiac activity
2)MSD>25mm without visible embryo
Time based criteria;
3) Absence of embryo with heart beat > 14 days after a scan that showed
GS without yolk sac
4) Absence of embryo with heart beat > 11 days after a scan that showed
GS with a yolk sac

18. 18

19. Problems of early pregnancy
 Miscarriage
 Ectopic pregnancy
 Gestational trophoblastic disease
 Ovarian problems
 Uterine fibroids
 Pregnancy with IUCD

20. Miscarriage
 Approximately 20% of women attending early pregnancy units suffer a
miscarriage
 Most women will present with history of vaginal bleeding and or
abdominal pain

21. Ultrasound findings
Miscarriage is classified into
 Threatened ; hx of vaginal bleeding + normal embryo seen by usg
 Missed ; absence of cardiac activity in fetal pole
 Blighted ovum ; absence of embryonic pole in a GS that measures 8
weeks
 Incomplete ; V.bleeding ,cramps + RPOC
 Complete ; V.bleeding ,cramps + thin endometrium “no RPOC”

22. 22

23. 23

24. Ectopic pregnancy
Is a life threatening condition
Presents with abdominal pain + amenorrhea +/- vaginal bleeding
Most commonly(95%) occurs in ampullary or isthmic portions of the
fallopian tube
Usg shows adnexal mass that contains a yolk sac or viable embryo

25. 25

26. Gestational trophoblastic disease
 GTD is a spectrum of both benign and malignant gestational tumors,
including hydatidiform mole (complete 46XX or XY—80 % or partial
69XXX or XXY )and gestational trophoblastic neoplasia.
 Uterine bleeding is the most common presentation
 Diagnosed by markedly elevated beta hCG level expected for the stage
of gestation and by the characteristic sonographic appearance from 8
weeks

27. Gestational trophoblastic disease
Complete mole; sonographic features
 Enlarged uterus
 May be seen as intrauterine mass with cystic spaces without any
associated fetal part, giving the appearance of snow storm or bunch of
grapes
Partial mole; well formed but growth retarded fetus
 Enlarged placenta, cystic spaces with in placenta

28. complete mole partial mole
29

29. Nuchal transluency
 Nuchal translucency is the normal fluid filled subcutaneous space
identified at the back of the fetal neck during the late 1st and early 2nd
trimester(11 to 14 weeks)
 Thickening of the nuchal translucency can be associated with
 Aneuploidy (down syndrome or turner syndrome)
 Congenital heart disease
 Noonan syndrome
 Miscarriage

30. 31

31. Heterotrophic pregnancy
Heterotrophic pregnancy is a rare condition when there is an
intrauterine and extrauterine pregnancy(i.e. ectopic pregnancy)
occurring simultaneously
32

32. 33

33. 34

34. 35