The Meaning of No Fetal Heartbeat on an Early Ultrasound

Miscarriage or Too Early to Tell?

Doctors examining pregnant woman
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Seeing your baby's heartbeat on an early pregnancy ultrasound is one of the surest indicators that a pregnancy is proceeding as it should—in general, the risk of miscarriage is much lower once the pregnancy has reached this point. But what does it mean if you go in for an ultrasound, and there is no fetal heartbeat? Does this indicate a miscarriage? What is the next step?

Should I Worry If No Fetal Heartbeat Is Detected on Ultrasound? 

Before looking into the possible reasons for the absence of a heartbeat on ultrasound, it is important to look at three questions.

If the answer to any of these questions is "no" - it could simply be that it is too early in your pregnancy for a heartbeat to be heard. When this is the case, and if you have no other symptoms, rechecking an ultrasound in a week is the most common recommendation.

Type of Ultrasound: Did you have an abdominal ultrasound or a transvaginal ultrasound? A transvaginal ultrasound (an ultrasound in which an ultrasound probe is inserted into your vagina to get better access to your uterus) is generally much more accurate in early pregnancy. Prior to eight weeks gestation, a transvaginal ultrasound provides by far the best results. Finding a fetal heartbeat on a handheld doppler can take even longer. You may be able to hear a fetal heartbeat with these devices at seven to eight weeks but may not hear a heartbeat until you are 12 weeks along.

Gestational age: The second important question to ask is how far along you are in pregnancy.

If you are not yet six or seven weeks pregnant, it is normal to not find a fetal heartbeat on an ultrasound. Using a transvaginal ultrasound, a developing baby's heartbeat should be clearly visible by the time a woman is seven weeks pregnant. Abdominal ultrasound is considerably less sensitive, so it can take longer for the heartbeat to become visible.

So, if you are less than seven weeks, you aren't likely to find a heartbeat.

The accuracy of your dates: The third most important questions to ask—if you believe you are at least seven weeks long and have had a transvaginal ultrasound—is whether your dates could be wrong. In early pregnancy, being off by a few days with your estimated last menstrual period, or having an irregular ovulation pattern can make a difference in whether or not you see a heartbeat on an early ultrasound. For example, if you did not ovulate exactly two weeks after your menstrual period started, there is a chance you are not really "seven weeks pregnant" in gestational age, even if it has been seven weeks since your last menstrual period.

What if There Is No Heartbeat on a Follow-Up Ultrasound?

Having a follow-up ultrasound after a week and detecting no change (still no heartbeat) raises the likelihood of miscarriage, but is also not a hard and fast rule. For example, If your periods were irregular and even though it is seven weeks from your last menstrual period, you may have been four weeks along in gestational age and still only five weeks along at a second ultrasound.

What if No Fetal Heartbeat Is Detected After Seven Weeks Gestation?

If you are past seven weeks pregnant, seeing no heartbeat may be a sign of miscarriage—but this is not a hard and fast rule.

There is many exceptions to the "heartbeat by seven weeks" rule, and you've likely heard of people who were certain they had miscarried or were not pregnant, and then went on to have a normal pregnancy.

Since there can be exceptions, and since the approach you take next is extremely important, researchers have developed guidelines as to when you can be fairly certain you have had a miscarriage.

When Might a Lack of a Fetal Heartbeat Indicate a Miscarriage?

Sometimes a lack of a fetal heartbeat does indicate a definite miscarriage. These situations would include:

  • Having previously seen the heartbeat but finding no heartbeat on a subsequent ultrasound.

Guidelines for Diagnosing a Miscarriage by Ultrasound

Different organizations have adopted different criteria as to when ultrasound findings indicate a miscarriage. 

The Society of Obstetrics and Gynecology of Canada criteria include:

  • No heartbeat in an embryo larger than 5 mm.
  • Gestational sac is larger than 8 mm and has no yolk sac.
  • Gestational sac is larger than 16 mm and has no embryo.

The American College of Obstetrics and Gynecology extend these guidelines to reduce false positives:

  • Use of absence of embryonic cardiac activity with a crown-rump length (CRL) cutoff of 5.3 mm rather than 5 mm (this appears to reduce false positives from 8.3 percent to none.
  • Use of a gestational sac means diameter of 21 mm without embryo (± yolk sac) rather than 16 mm, (which appears to reduce false-positive rates from 4.4 percent to none).
  • If a gestational sac is empty on initial scan, the continued absence of a yolk sac or embryo on a repeat scan ≥ 7 days is always associated with pregnancy loss.

What You Need to Know if You're Told You Have Miscarried

The guidelines listed above can be confusing for anyone. What is important is that you understand how and why your physician has come to the conclusion she has, and feel confident that she is correct. You need to feel at peace with your decision one way or the other, and you do not want to be second guessing your choices years from now.

If your physician is recommending treatment for a miscarriage after one ultrasound (or even after two) and you are not 100 percent sure that treatment is the right choice, you should discuss the matter with your physician and possibly ask for a follow-up ultrasound. Most of the time (but not always) there is no significant risk associated with waiting a few more days (as long as there is no indication of problems such as an ectopic pregnancy.)

Alternatively, you can always get a second opinion from another OB-GYN. Please remember that there's nothing wrong with getting the advice of another physician if you are in doubt.

A Word from Verywell

Having to wait for word on whether you're miscarrying is understandably difficult and may be one of the hardest weeks of your life—but it is definitely better to be absolutely sure before getting a diagnosis. Be your own advocate in your care. Ask as many questions as you need, and expect to receive clear and compassionate answers. For the medical professionals you work with, miscarriages are daily occurrences, but for you, they are not. In losing a pregnancy you are not only losing a child (a child that many people are already attached to) but the hopes and dreams that went with that child.

It is normal to grieve, whether it is the anticipatory grief that comes with wondering about the absence of a heartbeat or the grief of loss if you miscarry. As with other losses, people go through stages of grief after miscarriage. Here are a few tips which have helped others cope with a miscarriage. That said, everyone responds differently and that is okay. Honor yourself and grieve in the way that is best for you and your partner alone.