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ULTRASOUND |
Small
gestational sac prior to visualization of the yolk sac or embryo. Note
the marked vascularity on power Doppler at the site
of implantation. |
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TRUE GESTATIONAL SAC |
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Video clip of an
elongated gestational sac in a non-viable pregnancy. |
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Low implantation of gestational sac in lower uterine segment |
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Case 1 (above) – 5 weeks of gestation Case 2 (left) – 8 weeks of gestation
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“Intradecidual sign”. This differentiates a low lying pregnancy or cervical ectopic pregnancy from an abortion in progress.
This sign is only reliable prior to 12 weeks GA as the inferior portion of the gestational sac reaches the uterine corpus by 12 weeks GA.
Positive intradecidual
sign
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Negative intradecidual sign
Conceptus
and fluid is in the endometrial cavity and not within the decidua
(passing abortion). Other
signs associated with a negative intradecidual sign include: 1.
Hourglass
shape of the uterus due to enlargement of the cervix (80% cervical pregnancy and 25% passing abortion). 2.
Enlarged
corpus only in passing abortion (25%) but not in cervical pregnancy (in
passing abortion the pregnancy was initially in the uterine corpus whereas in
cervical pregnancy, the pregnancy was in the cervix from the beginning. 3.
External os is more frequently closed in passing abortion (80%)
than in cervical pregnancy (60%). 4.
Internal os is more frequently open in passing abortion (38%) than
in cervical pregnancy (20%).
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