Early pregnancy assessment (first trimester scan) Dr Shuhaila Ahmad Associate Professor...
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Transcript of Early pregnancy assessment (first trimester scan) Dr Shuhaila Ahmad Associate Professor...
Early pregnancy assessment(first trimester scan)
Dr Shuhaila AhmadAssociate ProfessorFeto-Maternal Unit
UKM Medical Centre
04/21/23
Scope of the lecture
• Importance of early pregnancy scan• Viable pregnancy• Non-viable pregnancy
– Miscarriage– Ectopic– Molar pregnancy
• Others – Multiple pregnancy– Nuchal translucency
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Importance of EP scan
• Determine:– Site of pregnancy– Gestational age– Viability– Fetal number– Pathology in the uterus and adnexae
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Ectopic pregnancy Intrauterine pregnancy
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Pregnancy with corpus luteal cyst
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Viable pregnancy
• Calculate gestational age using LMP• Scan the whole uterus and adnexae
systematically• Identify the IUGS
– Anechoic area within the uterine cavity– TVS : 4.5 – 5 weeks– Ensure not pseudogestational sac:
• Must see the throphoblastic rim around the GS• Identify the yolk sac
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Gestational sac
Trophoblastic rim
TVS
TAS
• If TVS: – fetal echo should be
present by 16mm– Presence of yolk sac
does not guarantee viable fetus.
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Yolk sac
Fetal echo
Gestational age
• Most accurate is the crown rump length• Least biological variation• Early gestation is better as at late gestation,
the fetus assumes flexion attitude• Beware not to include yolk sac into the
measurement• Wrong measurement may cause wrong EDD
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Gestational age
• Crown-rump length– Get the sagittal view in longest
image of the fetus– Enlarge the image to nearly 70% of
the monitor– Ensure the fetus in neutral
position– Measure from the highest point in
the head to the bottom end.– Do not include the legs– Do at least twice
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Which image is good for measuring CRL?
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Longest image but not sagittal
Longest axis, sagital view but the fetus is in flexion
Fetal viability
• Must be able to see pulsation– If unsure, use M mode
or colour doppler– Should be present if CRL
is 2-4mm– If > 5mm, no FH activity
may mean missed miscarriage
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Important discriminatory values
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Parameters suggestive of viable pregnancy
TAS TVS
Serum βHCG and presence of IUGS
6000 IU/L 2000 IU/L
Mean diameter of GC and presence of yolk sac
NA 8mm
Mean diameter of GC and presence of fetal echo
25mm 16mm
Mean fetal length (CRL) and presence of fetal heart activity
10mm 5mm
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Ectopic pregnancy
• Definition:– Pregnancy that is not present within the inner
lining of the uterus– 95% in the fallopian tubes
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Ultrasonographic features
• Empty uterus• Free fluid the POD• # complex mass / GS in
the adnexae
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U
Molar pregnancy
• Excessive pregnancy symptoms
• Uterus maybe palpable in first trimester
• Usually no fetal echo• Cavity filled up with
multiple sonolucent areas = snow storm appearance
• Presence of multiple theca lutein cysts in the ovaries
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Multiple pregnancies
• Determine number of fetuses• Determine chorionicity
– MC : “T” sign– DC : “λ” sign
• Determine viability• Determine gestational age
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Number of fetuses
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Chorionicity
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Nuchal translucency
• Between 11 to 13+6
weeks• About CRL of 45-84mm• Mid sagittal view of the
head• Just chest and the head
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Key points
• Determine LMP and gestational age• Identify uterus, adnexae and cervix• Identify site if gestational sac• Confirm viability and numbers• Determine gestational age by measuring the fetus
– Identification by TAS is delayed by I week compared to TVS
• Do not hesitate to proceed to TVS if needed• It will NOT increase bleeding or risk of miscarriage
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Thank you and
Good Luck for the hands on session 04/21/23