A blighted ovum is a
pregnancy
Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins.
Pregnancy usually occurs by sexual intercourse, but ca ...
in which the
embryo
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
never develops or develops and is reabsorbed.
In a normal pregnancy, an embryo would be visible on an ultrasound by six weeks after the woman's last menstrual period. Anembryonic gestation is one of the causes of
miscarriage
Miscarriage, also known in medical terms as a spontaneous abortion and pregnancy loss, is the death of an embryo or fetus before it is able to survive independently. Miscarriage before 6 weeks of gestation is defined by ESHRE as biochemical lo ...
of a
pregnancy
Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins.
Pregnancy usually occurs by sexual intercourse, but ca ...
.
A blighted ovum or anembryonic gestation is characterized by a normal-appearing
gestational sac
The gestational sac is the large cavity of fluid surrounding the embryo. During early embryogenesis it consists of the extraembryonic coelom, also called the chorionic cavity. The gestational sac is normally contained within the uterus. It is th ...
, but the absence of an embryo. It likely occurs as a result of early
embryonic death
Embryo loss (also known as embryo death or embryo resorption) is the death of an embryo at any stage of its development which in humans, is between the second through eighth week after fertilization. Failed development of an embryo often results ...
with continued development of the
trophoblast
The trophoblast (from Greek : to feed; and : germinator) is the outer layer of cells of the blastocyst. Trophoblasts are present four days after fertilization in humans. They provide nutrients to the embryo and develop into a large part of the p ...
. When small, the sac cannot be distinguished from the early normal pregnancy, as there may be a
yolk sac
The yolk sac is a membranous sac attached to an embryo, formed by cells of the hypoblast layer of the bilaminar embryonic disc. This is alternatively called the umbilical vesicle by the Terminologia Embryologica (TE), though ''yolk sac'' is ...
, though a
fetal pole
The fetal pole is a thickening on the margin of the yolk sac of a fetus during pregnancy.
It is usually identified at six weeks with vaginal ultrasound and at six and a half weeks with abdominal ultrasound. However, it is not unheard of for the f ...
is not seen. For diagnosis, the sac must be of sufficient size that the absence of normal embryonic elements is established. The criteria depends on the type of ultrasound exam performed. A pregnancy is anembryonic if a transvaginal ultrasound reveals a sac with a mean gestational sac diameter (MGD) greater than 25 mm and no yolk sac, or an MGD >25 mm with no embryo. Transabdominal imaging without transvaginal scanning may be sufficient for diagnosing early pregnancy failure when
an embryo whose crown–rump length is 15 mm or more has no visible cardiac activity.
See also
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Ovum
The egg cell, or ovum (plural ova), is the female reproductive cell, or gamete, in most anisogamous organisms (organisms that reproduce sexually with a larger, female gamete and a smaller, male one). The term is used when the female gamete is ...
*
Products of conception
References
External links
Blighted Ovumon WebMD
Anembryonic pregnancyon Radiopaedia.org
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{{DEFAULTSORT:Anembryonic Gestation
Health issues in pregnancy
Pregnancy with abortive outcome