A blighted ovum is a

pregnancy Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs ...

in which the

embryo An embryo ( ) is the initial stage of development for 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 sp ...

is reabsorbed or never develops at all. 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, is an end to pregnancy resulting in the loss and expulsion of an embryo or fetus from the womb before it can fetal viability, survive independently. Miscarriage before 6 weeks ...

of a

and accounts for roughly half of first-trimester miscarriages. A blighted ovum cannot result in a viable pregnancy. 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 the ...

, but the absence of an embryo. It likely occurs as a result of early

embryonic death Embryo loss (also known as embryo death) 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 in the disintegration ...

with continued development of the

trophoblast The trophoblast (from Greek language, Greek : to feed; and : germinator) is the outer layer of cells of the blastocyst. Trophoblasts are present four days after Human fertilization, fertilization in humans. They provide nutrients to the embryo an ...

. 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 wikt:sac, 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' ...

, 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. In anembryonic pregnancy, levels of the pregnancy hormone human chorionic gonadotropin (hCG) typically rise for a time, which can cause positive pregnancy test results and pregnancy symptoms such as tender breasts. Because of the presence of hCG, an ultrasound is typically necessary to diagnose an anembryonic pregnancy. 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

transvaginal ultrasound Vaginal ultrasonography is a medical ultrasonography that applies an ultrasound transducer (or "probe") in the vagina to visualize organs within the pelvic cavity. It is also called transvaginal ultrasonography because the ultrasound waves go ''a ...

provides a better view of early pregnancy than a transabdominal ultrasound. Generally, a transvaginal ultrasound is used to investigate a suspected case of blighted ovum. 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. A transabdominal ultrasound can be used to diagnose anembryonic pregnancy if a gestational sac can be identified, but is empty. An anembryonic pregnancy is never viable, as in viable pregnancy the embryo must form with the gestational sac.

References

External links

Blighted Ovum
on WebMD
Anembryonic pregnancy
on Radiopaedia.org *
Facts Are Important: Understanding and Navigating Viability
on ACOG {{DEFAULTSORT:Anembryonic Gestation Health issues in pregnancy Pregnancy with abortive outcome

See also

References

External links