Fertility & conception

Blighted Ovum: When a Sac Grows Without an Embryo

Save

A blighted ovum, or anembryonic pregnancy, is an early loss where a gestational sac forms but no embryo grows inside. hCG keeps rising for a while, so a test stays positive until an ultrasound shows the empty sac. It usually stems from a chromosomal error and rarely affects future pregnancies for most people.

Last updated: July 2026

Talk to a clinician

Gale can help you find a clinician in your state and request a visit.

Find care →

Continue in Claude

Open a chat with this article’s link already in the message, and keep asking questions there. Claude reads the article and its sources; nothing about you is included.

Continue in Claude →

The button opens the Claude desktop app and fills in the message for you to review before sending. No desktop app, or reading on a phone? Copy the prompt and paste it into any AI.

What is a blighted ovum?

A blighted ovum is a pregnancy where the sac develops but the embryo does not. After fertilization, the fertilized egg implants and begins forming the gestational sac and placenta, which release hCG, so a pregnancy test reads positive and you may feel pregnant 1. In an anembryonic pregnancy the embryo either never forms or stops at the earliest stage, leaving a sac that keeps growing for a time without a baby inside.

The clinical name, anembryonic gestation, simply means no embryo. Because hormone levels rise early on, many people have no warning until an ultrasound is done. Early symptoms can mimic a normal pregnancy, which is part of why the news can be so disorienting.

How is a blighted ovum diagnosed?

A blighted ovum is diagnosed by ultrasound, and clinicians confirm it carefully before acting. Obstetric criteria consider a pregnancy anembryonic when the gestational sac reaches a mean diameter of 25 mm or more with no visible embryo 1. Because early dating can be off by 3 to 5 days, a single scan is often not enough.

Guidance recommends a repeat ultrasound about 7 to 14 days later to be certain before a diagnosis is made 2. This cautious approach prevents mistaking a normal but early pregnancy for a loss. According to national guidance, waiting for these criteria protects against acting too soon 2. Confirmation, not a single image, drives the diagnosis.

Why does a blighted ovum happen?

A blighted ovum almost always traces to a chromosomal error present from fertilization. About 50% of first-trimester losses involve random chromosomal abnormalities that keep the embryo from developing, and an anembryonic pregnancy is one such outcome 1. These are chance events, not the result of exercise, stress, work, or past birth control.

They do become more common with age, which is why early loss rises after age 35 and climbs further after 40. A blighted ovum is rarely caused by anything preventable, and it is not a sign that your body rejected a healthy pregnancy. For most people it is a one-time event rather than a pattern that will repeat.

What happens after a blighted ovum?

After a confirmed blighted ovum, the pregnancy tissue can pass in one of a few ways. Options include waiting for it to pass naturally, medication to help it along, or a minor procedure, and outcomes are similar enough that preference and situation guide the choice 1. A single anembryonic pregnancy does not lower your future odds, and most people go on to conceive successfully.

There is no medically required waiting period before trying again, though many want time to grieve. Reviewing why miscarriages happen can ease the self-blame that often follows an empty-sac diagnosis, and how long conception usually takes can steady expectations. Repeated losses are a separate situation that warrants its own evaluation 3.

When an empty-sac loss needs a clinician

An empty-sac loss needs a clinician's involvement to confirm the diagnosis and choose how to manage it. An obstetrician-gynecologist can verify the criteria on a repeat scan, discuss whether to wait, use medication, or do a procedure, and check that the tissue has fully passed.

If you have had two or more losses, a clinician may suggest testing rather than assuming chance 3. Reviewing recurrent miscarriage testing and when to see a fertility specialist can help you plan. Gale can help you prepare for that conversation.

Common questions

No. Once a blighted ovum is confirmed on a repeat scan, meaning a gestational sac has grown past the size threshold with no embryo, it will not develop into a viable pregnancy. That is exactly why clinicians confirm it carefully before making the diagnosis.

Because the developing placenta keeps producing hCG for a time, early pregnancy symptoms like sore breasts or nausea can continue even when no embryo is present. This is normal and does not mean you missed a sign; the empty sac is only visible on ultrasound.

Not always. After a confirmed diagnosis, you may be able to wait for the tissue to pass on its own, use medication to help it along, or choose a minor procedure. Outcomes are broadly similar, so the choice often comes down to preference and your situation.

Usually not. A single blighted ovum is typically a one-time, chance event and does not lower the odds of a healthy pregnancy next time. Repeated losses are a different situation, and two or more is the point at which evaluation is generally offered.

Related

Say it back

How would you explain this to someone you love?

Two or three sentences, just as you’d say it. Gale reflects back what you focused on — a mirror, not a quiz.

Talk to a clinician

Gale can help you find a clinician in your state and request a visit.

Find care →

When a suspected early loss needs review

  • —Very heavy bleeding that soaks a pad an hour for two or more hours is a reason to seek urgent medical care
  • —Severe or one-sided pelvic pain, shoulder-tip pain, or fainting is a reason to seek emergency care to rule out an ectopic pregnancy
  • —Fever or foul-smelling discharge after bleeding is a reason to seek same-day clinician review
  • —Two or more early pregnancy losses is a reason to ask a clinician about evaluation

If bleeding soaks a pad an hour, or you have severe one-sided pain, shoulder-tip pain, or fainting, call 911 or go to the nearest emergency room to rule out an ectopic pregnancy or hemorrhage.

This article is general health education, not medical advice. A blighted ovum is diagnosed and managed with an obstetrician-gynecologist, who confirms the criteria before any decision is made.

References

  1. 1.American College of Obstetricians and Gynecologists (2018). ACOG Practice Bulletin No. 200: Early Pregnancy Loss. Obstetrics & Gynecology. doi:10.1097/AOG.0000000000002899 ✓Diagnostic criteria for anembryonic (blighted ovum) pregnancy include a mean gestational sac diameter of 25 mm or more with no embryo; about half of first-trimester losses are chromosomal; management options include expectant, medical, and surgical approaches with similar outcomes
  2. 2.National Institute for Health and Care Excellence (2026). Ectopic pregnancy and miscarriage: diagnosis and initial management (NG126). National Institute for Health and Care Excellence (NICE). link ✓A repeat ultrasound after an interval, commonly about 7 to 14 days, is recommended to confirm an early pregnancy loss before a diagnosis is made, protecting against acting on a single early scan
  3. 3.Practice Committee of the American Society for Reproductive Medicine (2026). Recurrent pregnancy loss: a committee opinion. Fertility and Sterility. doi:10.1016/j.fertnstert.2026.03.001 ✓Two or more pregnancy losses meet the definition of recurrent pregnancy loss and warrant a dedicated evaluation rather than being attributed to chance

3 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — every citation independently verified. Editorial policy

← Back to the health library