3. Early Pregnancy Ultrasound report
NORMAL
ABNORMAL
Location
Structure
Viability
Dating
Number
•Assessment of other pelvic masses ????
•Screening for fetal abnormalities ????
•Assisting CVS and amniocentesis????
5. Structures of 1st Trimester
Pregnancy
Gestational sac
Yolk sac
Embryo/fetus
Presence of cardiac activity
6. Gestational sac
Visible at 4-5wks GA with
TVUS & at 6 wks GA with
TAUS.
Eccentric echogenic ring with
anechoic center .
Measure by Mean Sac
Diameter.
GS size increases by about
1mm/day in early pregnancy
Discriminatory zone: serum
hCG level in which GS is
expected to be visible by US :
hCG >2000 mIU/ml by
TVUS& hCG >6000 mIU/ml
by TAUS
7. Structures of 1st Trimester
Pregnancy
Yolk sac: : bright ring with anechoic center located inside GS
seen at 5wk GA & persists to 11-12 weeks.
Embryo/fetus: seen by TVUS as thickening of yolk at 6wks GA.
Presence of cardiac activity: usually seen around the time
fetal pole is present, further confirming viability (6th wks)
Yolk sac
Fetal pole
12. 12
10/28/14
Early ddaattiinngg ooff pprreeggnnaannccyy
5 – 9 weeks : use of mean GS diameter
6 – 12 weeks : use of CRL (most accurate
dating of early pregnancy)
After 12 weeks : use of BPD
13. Formulas to Calculate
gestational age
MGSD (mm) + 30
= gestational age
(days) (between 5
and 9 weeks)
CRL (mm) + 42 =
gestational age
(days) (between 6
and 12weeks)
18. Twin peak (or Lambda sign) pathognomonic
for dichorionic placentation
T-sign pathognomonic
for monochorionic placentation
19. Other roles of US
Confirm fetal number .
Confirm viability.
Diagnosis of vanishing twin syndrome.
Exclude any malformation or conjoined twins
(especially at age > 35y = genetic
amniocentesis)
Needed with other procedures
CVS
fetal reduction
21. Abnormal early (first trimester)
pregnancy
FFaaiilleedd eeaarrllyy pprreeggnnaannccyy..
Pregnancy of uncertain viability (i.e. IU pregnancy in a situation with no
enough criteria (usually on ultrasound grounds) to confidently categorize a pregnancy
as a miscarriage).
Pregnancy of unknown location.
Ectopic pregnancy
Trophoblastic disease
Subchrionic hemorrhage
Incomplete abortion (retained products of conception)
23. Failed early
pregnancy
(FEP(
Pregnancy of
uncertain viability
(PUV(
NNoo ccaarrddiiaacc aaccttiivviittyy
wwiitthh CCRRLL
≥≥77mmmm < 6mm
No fetal pole with
MSD
> 25 mm
(Anembryonic
Pregnancy)
< 20mm
Others Absence or inadequate
growth on serial scans
at least 7-10 days
Mean GSD < 25mm
and containing yolk
sac only
Management Termination Follow up US in 7-14 days with
serial beta HCG correlation…
viable or nonviable.
TVUS criteria of :
Doubilet et al., N Engl J Med. 2013 Oct
10;369(15):1443-51
24. US poor prognostic indicators of
pregnancy include:
No yolk sac, where:
MSD > 8 mm
embryo seen
Irregular gestational sac
Low position of the gestational sac
Doubilet et al., N Engl J Med. 2013 Oct
10;369(15):1443-51
27. Pregnancy of unknown location
(PUL)
PUL = +ve pregnancy test + no IU or
Ext.U pregnancy in US scan
↓↓↓↓↓
Differential diagnosis is:
1. very early pregnancy, not detected with
ultrasound
2. complete miscarriage
3. unidentified ectopic pregnancy
37. Cer vical ectopic pregnancy
GS within the cervix .
Abnormally low sac position.
Colour Doppler : hypervascular trophoblastic
ring in the cervical region .
38. Interstitial ectopic pregnancy
Eccentric gestational sac: the diagnosis is suggested by
visualisation of an intrauterine gestational sac or
decidual reaction located high in the fundus, that is
surrounded by less than 5 mm of myometrium in all
planes.
Interstitial line sign : an echogenic line from the mass to
the endometrial echo .
39. Sonographic features of Caesarean scar
ectopic pregnancy (CSEP)
empty uterus
empty cervical canal
GS in the anterior part of
the lower uterine segment
absence of myometrium
between the bladder wall
and the GS
44. Thickened Nuchal Tanslucency (NT):
Used for screening (SS) for Down’s syndrome in first trimester
Serial screening: Pregnancy associated plasma protein levels, hCG levels, NT
thickness
Measured during 11-14 wks gestational age
Seen on sagittal image as increased subcutaneous non-septated fluid in posterior
fetal neck
Measurement >3mm usually considered abnormal, however exact cut off
measurements are dependent on maternal age/gestational age
Detection rate of screening for Down’s Syndrome in first trimester:
sequential screening with NT: 82-87%
NT alone: 64-70%
45. Safety of ultrasound in pregnancy
General perception is that ultrasound is safe (It is not
ionising radiation)
However, bioeffects can be either thermal or mechanical
(i.e. cavitations) with high power ultrasound
One RCT of repeated routine ultrasound with Dopplers in
the 3rd trimester found a small but significant decrease in
birth weight in the exposed cohort
A meta analysis showed males exposed to ultrasound in
uterus are more likely to be left-handed
46. How to reduce biohazards
ALARA
As Low As Reasonably Achievable
ALARA principle:
Lowest acoustic power
Shortest duration
Least exposure to sensitive target tissues
47. Take home message
Ultrasound is no substitute for a good history
ALWAYS do an abdominal scan with ( Full bladder)
before using the vaginal probe with ( Empty bladder)
You will always be better than sonographers because
you know the anatomy and pathology
Avoid premature conclusions
48. Take home message
Systematic scan should be performed
US scans are useful to be combined with HCG tests
before decision.
With ultrasound , an early intervention or
conservative management in pregnancy can be
determined.
General perception is that ultrasound scan is safe in
pregnancy.