A positive pregnancy test can bring a rush of plans—appointments, family conversations, a quick calculation of due dates. Then a scan report mentions an “empty sac”, and one phrase keeps coming back: blighted ovum. Is it definite? Could it be too early? What happens to the body, and what are the safest options?

A blighted ovum is an early pregnancy loss where the gestational sac forms in the uterus, but the embryo does not develop to a stage that can be seen on ultrasound. Because pregnancy hormones may still be produced for a short time, symptoms can continue, which often adds to the confusion.

Blighted ovum explained in clear terms

What a blighted ovum is (anembryonic pregnancy, “empty sac”)

A blighted ovum (medical term: anembryonic pregnancy) occurs when implantation happens and the gestational sac starts developing, but an embryo never forms—or stops developing extremely early. On ultrasound, the finding is typically an empty gestational sac.

You may still feel pregnant. Why? Early placental tissue (the trophoblast) can continue to grow briefly and release hCG (human chorionic gonadotropin). So nausea, breast tenderness, tiredness, and a positive urine test can persist even when the embryo is not developing.

Sometimes a yolk sac is seen first (an early structure that supports development), and then growth stops. If dates are uncertain—late ovulation, irregular cycles, or delayed implantation—doctors commonly plan a follow-up scan before confirming a blighted ovum.

How it differs from miscarriage, missed miscarriage, and chemical pregnancy

“Miscarriage” is a broad term for pregnancy loss before 20 weeks. A blighted ovum is one type of early miscarriage.

A missed miscarriage also means the pregnancy is no longer viable, but the body has not yet expelled the tissue. The key difference is ultrasound:

• Missed miscarriage: an embryo was present earlier but is no longer developing (often no heartbeat).
• Blighted ovum: the sac grows, but no embryo is visible.

A chemical pregnancy ends even earlier—after a positive test but before an ultrasound can confirm a gestational sac. With a blighted ovum, the pregnancy usually progresses far enough that a sac is seen inside the uterus.

Blighted ovum vs ectopic pregnancy vs molar pregnancy

A blighted ovum is an intrauterine pregnancy (in the uterus). An ectopic pregnancy implants outside the uterus, commonly in a fallopian tube, and can become a medical emergency if it ruptures. Early symptoms can overlap, and hCG levels alone cannot reliably separate the two. Ultrasound follow-up is the key.

A molar pregnancy is different again: abnormal placental tissue growth (gestational trophoblastic disease). Ultrasound often looks unusual, and hCG can be higher than expected for gestational age. Follow-up after a molar pregnancy is more intensive.

How common a blighted ovum is

Early pregnancy loss happens in around 15% of clinically recognised pregnancies, and the true number is higher because many losses occur before any scan. Anembryonic pregnancy is a common reason for first-trimester loss.

How age can affect risk

Age matters because chromosomal errors become more common over time. The risk of early pregnancy loss rises after 35 and increases further after 40. For blighted ovum specifically, studies often show a marked rise with age, reflecting higher rates of chromosomal abnormalities.

When it’s usually discovered

A gestational sac may be seen around 4–5 weeks on transvaginal ultrasound, but an embryo is usually visible by around 6 weeks in a viable pregnancy. Many blighted ovum diagnoses are made around 7–9 weeks, often after a dating scan or a scan done for bleeding.

What causes a blighted ovum

Chromosomal abnormalities and genetic factors

The most common cause of blighted ovum is a chromosomal abnormality in the fertilised egg—often aneuploidy (extra or missing chromosomes). In most cases, it is random and not linked to daily activities.

More rarely, a parent may carry a balanced translocation or other balanced chromosomal rearrangement. This is usually considered when there are repeated losses.

What happens after implantation

Implantation can start the early pregnancy programme: sac formation, trophoblast growth, and hCG production. But the embryo fails to develop or stops extremely early. That mismatch—sac growth without embryo development—is what shows up later on ultrasound as a blighted ovum.

Other factors sometimes discussed (less common)

Depending on history, clinicians may also discuss:

• Uterine cavity anomalies (septum, adhesions, fibroids affecting the cavity)
• Selected immune or clotting-related conditions
• Certain infections

Even with careful follow-up, a clear cause may not be identified in an individual case.

Risk factors that can increase the chance of a blighted ovum

• Advanced maternal age
• Previous miscarriage or previous blighted ovum (risk increases more clearly when losses repeat)
• Thyroid disease, poorly controlled diabetes
• Obesity
• Uterine anomalies or fibroids distorting the uterine cavity
• Smoking, alcohol, and exposure to certain toxins (some solvents, pesticides, heavy metals)

Many people have a blighted ovum without any obvious risk factor.

Blighted ovum symptoms and when to get help

Pregnancy symptoms that can still happen (and why they may fade)

Because trophoblast tissue can keep releasing hCG for a while, symptoms like nausea and breast tenderness can continue. As hormone levels plateau and then fall, symptoms often fade. Symptom change alone cannot confirm a blighted ovum—ultrasound and follow-up provide the answer.

Bleeding or spotting, cramps, and pelvic pain

Bleeding can start as spotting and become heavier, sometimes with clots or tissue. Cramps—like period cramps—may occur and may become stronger as the uterus empties.

When there are no symptoms

Some parents have no warning signs. The diagnosis of blighted ovum is made during an ultrasound where the sac is seen but no embryo is visible.

Urgent warning signs

Seek urgent care if you have:

• Bleeding soaking more than two pads per hour for two hours
• Severe or worsening pelvic/abdominal pain
• One-sided pain, especially if increasing (ectopic pregnancy must be ruled out)
• Dizziness, fainting, or marked weakness
• Fever, chills, foul-smelling discharge, or feeling very unwell

How a blighted ovum is diagnosed

Ultrasound findings: empty sac and yolk sac scenarios

Transvaginal ultrasound is commonly used early because it gives better resolution. The typical picture is an intrauterine gestational sac with no embryo. A yolk sac may be present or absent.

Mean sac diameter (MSD) and criteria used

Clinicians may use the mean sac diameter (MSD) to avoid a wrong diagnosis in a very early pregnancy. A commonly used threshold is an MSD of around 25 mm with no embryo on transvaginal ultrasound, supporting nonviability. Some centres use a range (around 20–25 mm) depending on guideline and scan quality. This is why repeat imaging is often planned when dates are uncertain.

hCG levels and trends (why one value is not enough)

Serial quantitative hCG helps track progression, but a single hormone value cannot confirm viability. In blighted ovum, hCG may rise slowly, plateau, or begin to fall, and can remain elevated for a while.

Repeat ultrasound: why waiting can be protective

If the first scan is early or unclear, doctors usually schedule a repeat scan rather than rushing to a conclusion. Many protocols re-scan about 7–14 days later (timing depends on what was seen). The aim is straightforward: confirm lack of progression and avoid ending a pregnancy that is simply earlier than expected.

Ruling out ectopic pregnancy and pregnancy of unknown location

If an intrauterine pregnancy is not clearly seen, clinicians may label it as pregnancy of unknown location and follow hCG and ultrasound until location and viability are clear.

Timeline: how a blighted ovum develops

• 4–5 weeks: gestational sac may be visible
• 5–6 weeks: yolk sac may appear
• 6–7+ weeks: embryo is usually expected in a viable pregnancy, persistent absence raises concern for blighted ovum
• 7–9 weeks: diagnosis is often confirmed, sometimes after repeat imaging

hCG may rise initially, then plateau or fall. Symptoms can persist early and then fade. Bleeding and cramps often start when the body begins passing pregnancy tissue—timing varies widely.

Treatment options for a blighted ovum

There are three accepted options: expectant (waiting), medical, and surgical. The best choice depends on bleeding, pain, infection risk, scan findings, your medical history, and access to follow-up.

Expectant management

The body passes tissue naturally. It can take days to weeks. Bleeding may be on-and-off, sometimes heavier in waves. Follow-up is important, because miscarriage can be incomplete.

Medical management: misoprostol (and sometimes mifepristone)

Medical management usually uses misoprostol to help the uterus contract and expel tissue. Some protocols add mifepristone beforehand to improve effectiveness.

Expected:

• Strong cramping for a period of time
• Bleeding heavier than a usual period, often with clots

A follow-up scan is commonly planned to check the uterus has emptied.

Surgical management: suction aspiration / D&C

Surgical management (often suction aspiration, commonly referred to as D&C) removes pregnancy tissue in a short procedure, usually as outpatient care. It may be preferred if bleeding is heavy, infection is suspected, there is anaemia risk, you want faster closure, or expectant/medical care has not completed.

Rh status and anti-D

If you are Rh-negative, the team may discuss anti-D (Rh immune globulin) after miscarriage or uterine procedures, depending on gestational age and local protocol.

What to expect during treatment and follow-up

Bleeding and cramping depend on the approach:

• Expectant: light-to-moderate bleeding for days to weeks, heavier when tissue passes
• Medical: bleeding often starts within hours, can be heavy initially, then tapers
• Surgical: bleeding is often lighter and shorter afterwards

For comfort, many people use ibuprofen or paracetamol (if suitable), a heating pad, hydration, and rest. Use pads rather than tampons during bleeding.

Completion can be confirmed by symptom improvement, ultrasound, and/or falling hCG to a negative level. Contact your clinician quickly for fever, worsening pain, foul discharge, or very heavy bleeding.

Complications and when to seek care

Seek urgent care if you soak more than two pads per hour for two hours, feel faint, develop fever/chills, have worsening abdominal pain, or notice foul-smelling discharge. Persistent fatigue, breathlessness, or palpitations after heavy bleeding can suggest anaemia. Persistent bleeding or cramps may point to retained tissue.

Physical recovery after a blighted ovum

Cramping often improves within about a week. Bleeding may last up to a few weeks and should gradually taper.

The first period often returns around 4–6 weeks, though some variation is normal. Ovulation can happen before the first period, so pregnancy can occur quickly.

Home pregnancy tests may stay positive for a while as hCG falls. If tests stay positive for long, clinicians may check serial hCG.

Resume daily activity as you feel able. Use pads until bleeding stops. Sex is usually postponed until bleeding has resolved and you feel ready.

Emotional recovery and supportive care

A blighted ovum can bring grief that feels sharp and unexpected. Sadness, anger, guilt, numbness—any mix can show up, and hormonal shifts may intensify mood changes.

Partners often grieve differently. It may help to say plainly what you need: quiet company, conversation, help with meals, or space.

If sleep is severely disturbed, anxiety is constant, or day-to-day functioning is affected for more than a couple of weeks, professional mental health support is appropriate.

Getting pregnant again after a blighted ovum

Many clinicians suggest waiting for one normal menstrual cycle (sometimes one to two cycles) for easier dating and uterine recovery. Emotional readiness matters just as much.

Most people have a healthy pregnancy after a single blighted ovum. Recurrence after one event is usually low. If there are two consecutive miscarriages (or three, depending on protocol), clinicians often discuss evaluation for recurrent pregnancy loss.

Preventing early pregnancy loss: what can and can’t be controlled

No plan can guarantee prevention of blighted ovum, because many cases are due to chance chromosomal changes at fertilisation or early cell division.

Still, preconception care supports overall pregnancy health:

• Folic acid (often 400–800 micrograms daily unless advised otherwise)
• Medication and supplement review
• Optimising thyroid disease and diabetes
• Avoiding smoking and alcohol while trying
• Limiting exposure to solvents, pesticides, and heavy metals where possible

Stress, moderate exercise, sex, and routine travel do not cause blighted ovum.

To remember

• A blighted ovum (anembryonic pregnancy) is an early loss where a gestational sac forms in the uterus but no embryo develops.
• Symptoms and a positive test can continue temporarily because hCG may persist.
• Diagnosis relies on transvaginal ultrasound, often with a planned repeat scan, hCG trends can support follow-up but cannot confirm viability alone.
• Options include expectant care, medication (often misoprostol), or a procedure (suction aspiration/D&C), with follow-up to confirm completion.
• Seek urgent care for very heavy bleeding, severe or one-sided pain, dizziness/fainting, fever, chills, or foul-smelling discharge.
• Support exists through your gynaecologist and care team, and you can download the Heloa app for personalised guidance and free child health questionnaires.

Further reading :

• Blighted ovum: What causes it? (https://www.mayoclinic.org/diseases-conditions/pregnancy-loss-miscarriage/expert-answers/blighted-ovum/faq-20057783)
• Anembryonic Pregnancy – StatPearls – NCBI Bookshelf – NIH (https://www.ncbi.nlm.nih.gov/books/NBK499938/)