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DOUBLE DECIDUAL
REACTION |
The "Double Decidual Sign", first described by Nyberg and co-workers consists of two echogenic rings surrounding the hypoechoic gestational sac.
The inner ring represents the chorion, embryonic disc and decidua capsularis (*). The outer ring represents the decidua parietalis (**).
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LAYERS OF THE DECIDUA(13-14 DAYS
POST-FERTILIZATION) |
- Decidua basalis - situated beneath the implanted embryo.
- Decidua capsularis - covers the rest of the chorionic sac.
- Decidua parietalis - lines the portions of the uterine cavity that is not involved in implantation.
A hypoechoic area may
occasionally be seen between the inner and outer rings, and represents the
compressed uterine cavity adjacent to the gestational sac.
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The hypoechoic
area between the inner and outer rings represents the compressed
uterine cavity adjacent to the gestational sac. |
SINGLE DECIDUAL RING |
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A single decidual ring or hypoechoic area may be visualized in the uterine
cavity. This may be due to a decidual cast and fluid in the endometrial cavity. This appearance can be found in
the presence of an ectopic pregnancy.
REFERENCES |
- Nyberg DA, Laing FC, Filly RA et.al. Ultrasonographic differentiation of the gestational sac of early intrauterine pregnancy from the pseudogestational sac of ectopic pregnancy. Radiology 1983;146:755-759.