2. Definition
• Early pregnancy is described as first 12
weeks from beginning of the last normal
menstrual period to the end of the first
three months.
3. Things to look for in Early
Pregnancy Ultrasound
• Gestational Sac
• Yolk sac
• Embryo
6. 2.Gestational Sac
Important features to look for
• Double decidual sac
• Continuous hyper-echoic rim of at least 2mm in
thickness
• Spherical or ovoid shaped without marked
angulations.
• Growth of more than 1.2 mm/ day
7. 3. Gestational Sac
Characteristics of Abnormal Sac
• Distorted Contour
• Thin decidual rim ( < 2mm) echoic rim
• Weakly hyper-echoic rim
• Low GS position
• Note: when in doubt , advice Follow Up
scan
8. Double Decidual Sac
• Useful and seen in majority of normal
pregnancies
• Hyper-echoic rim without DDS more likely
in
– Abnormal IUP
– Pseudo-gestational sac of fluid
9. Double Decidual Sac sign
• This consist of two concentric echogenic
rings, surrounding at least a part of
gestational sac.
• It differentiates it from pseudo-gestational
sac which is seen in ectopic pregnancy, in
which only a single echogenic layer of
decidua surrounds an intra-endometrial
fluid collection.
11. Embryo
• Trans-vaginally
– Often seen when MGSD of approx 12 mm ( 6.2 weeks)
– Almost always seen with MGSD of 16 mm
– Still no embryo at 25 mm – consider pregnancy abnormal
• Trans-abdominally
– MGSD at least 27 mm or 8.1 weeks
12. Complications of Early Pregnancy
• Bleeding in first trimester:
Possible explanations:
– Intrauterine Pregnancy 50%
– Missed abortion 25-30%
– Blighted ovum 20-25%
– Incomplete abortion
– Inevitable abortion
– Complete spontaneous abortion
– Ectopic Pregnancy
– Hydatidiform Mole
13. Intrauterine Pregnancy
characteristics
• Gestational Sac
– Gestational sac
– yolk/sac embryo
– foetal heart
– Gestational sac is round or oval with smooth
contour and generally located in the fundus or
middle uterus
14.
15. Intrauterine Pregnancy
Transvaginal ultrasound image showing intrauterine gestation at 59 days LMP.
Calliper's clearly mark a crown to rump length (CRL) of 17 mm.
Yolk sac can also be seen.
16. Missed Abortion
• Fetus without heart or limb motion which still
remains with in the gestational sac
• Standing Joint Committee (Royal Colleges of Radiologist,
Obstetrician and Gynaecologist) on Obstetric Ultrasound
has indicated that on TVS, if an embryo greater
than 6 mm in length has no evidence of cardiac
pulsation than this is highly suggestive of missed
abortion
17. Missed Abortion
These ultrasound images show an intrauterine gestation sac with an abnormally
large yolk sac (7mm size). This pregnancy is of 10 weeks gestational age (going by
the date of last menstrual period). However the poorly developed embryo
measures 6 mm. in size (6 weeks 2 days) and shows no cardiac activity. These
ultrasound findings suggest embryonic demise. (Note: By current criteria, an
embryo of more than 5 mm. in size showing no cardiac activity on transvaginal
sonography, is considered to be non-viable/ case of embryonic demise).
18. Blighted ovum
• An embryonic pregnancy in which
gestational sac is present but empty
• Standing Joint Committee (Royal Colleges
of Radiologist, Obstetrician and
Gynaecologist) has indicated that on TVS
a sac diameter of greater than 20 mm with
no yolk sac or embryo is highly suggestive
of blighted ovum.
19.
20. Blighted Ovum
This picture shows bulky (enlarged) gravid uterus showing a gestation sac of
13mm. (5 weeks, 1 day).
The images show absence of the embryo. These ultrasound images suggest an
embryonic gestation (usually known as missed abortion or blighted ovum).
It is advisable to repeat the sonography (after 1 week to 10 days ), in such cases to
rule out delayed development of the embryo.
21. Incomplete Abortion
• Only part of products of conception remains with in the
uterus, the remainder having been expelled.
• Findings will vary in these cases. Sometimes, it is
obvious that there is nothing left inside the uterus, as
evidenced by a thin, complete endometrial stripe. In
other cases, there will be obvious pregnancy tissue. In
the remaining cases, some material will still be present
inside the uterus, but it won't be clear (on ultrasound)
whether this is blood, blood clot, or retained products of
conception.
22. Incomplete Abortion
This image shows an endovaginal longitudinal view of a
low-lying gestational sac within the uterus representing an
incomplete miscarriage.
23. Inevitable Abortion
• Gestation sac and the fetus has been
detached from the implantation site and lie
in the lower uterine segment or vaginal
canal. Once cervix becomes dilated
abortion is inevitable.
24. Inevitable Abortion
Abortion in Progress. Trans abdominal image shows a gestational sac
containing a dead embryo presenting at an open cervical os. Expulsion of the
pregnancy is inevitable. The balloon of a Foley catheter is evident in the
bladder.
29. Ectopic Pregnancy
• Implantation of fertilized ovum outside the
endometrial lining of the uterus
• This may occur within the peritoneal cavity,
fallopian tubes, ovaries, cervix or within a scar of
prior uterine surgery. 95% of all ectopic
pregnancies occur within the fallopian tubes.
• The most definitive sonographic sign of ectopic
pregnancy is the visualization of an extrauterine
gestational sac containing a yolk sac, embryo or
fetal heart beat. This occurs in approximately
14% of ectopic pregnancies.
33. Hydatidiform mole
• When the pregnancy test is positive and
ultrasound detects multiple, hypoechoic
and hyperechoic spaces filling and
distending the endometrium canal (without
a well defined embryo), H Mole is likely.
