The Meaning of No Fetal Heartbeat on an Early Ultrasound

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 and a fetal heartbeat has been detected.

Sadly, the reverse is also true. If you go in for an ultrasound, and there is no fetal heartbeat, there is a higher likelihood that the pregnancy will not be carried to term. Miscarriage is one explanation for no fetal heartbeat. However, there are multiple other reasons why the heartbeat of a healthy fetus is not being picked up.

Why Fetal Heartbeat May Not Be Detected

There are a few possible reasons for the absence of a heartbeat on ultrasound. If you have no other symptoms, rechecking with another ultrasound seven to 10 days is the most common recommendation.

Type of Ultrasound

A transvaginal ultrasound (an ultrasound in which a probe is inserted into your vagina to get better access to your uterus) is generally much more accurate than an abdominal ultrasound in early pregnancy. Prior to eight weeks gestation, 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. Or you may not hear a heartbeat until you are 10 weeks along.

Gestational Age

If you are less than seven weeks pregnant, it's unlikely to find a heartbeat by ultrasound. Using 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.

Accuracy of Your Dates

If you believe you are at least seven weeks along and have had a transvaginal ultrasound that did not detect a fetal heartbeat, consider whether your dates could be wrong. In early pregnancy, being off by a few days or having an irregular ovulation pattern can make a difference.

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. This is true even if it has been seven weeks since your last menstrual period.

No Heartbeat on Follow-Up Ultrasound

If you have a follow-up ultrasound after a week and there is no change (still no heartbeat), the likelihood of miscarriage is greater. But it may still be too early in your pregnancy for a heartbeat to be found. If your periods were irregular, even though it is seven weeks from your last menstrual period, you may still be only five weeks along at a second ultrasound.

No Fetal Heartbeat After Seven Weeks Gestation

If you are past seven weeks pregnant, seeing no heartbeat may be a sign of miscarriage. But there are many exceptions to the "heartbeat by seven weeks" rule. 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 the approach you take next is extremely important, medical authorities have developed guidelines as to when you can be fairly certain you have had a miscarriage.

Lack of a Fetal Heartbeat Indicating Miscarriage

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

• Having previously seen the heartbeat but finding no heartbeat on a subsequent ultrasound
• Seeing no heartbeat and having falling hCG levels
• Having ultrasound measurements that indicate a heartbeat should definitely be present

Guidelines for Diagnosing a Miscarriage by Ultrasound

Organizations have adopted different criteria as to when ultrasound findings indicate a miscarriage. Research shows that a heartbeat should definitely be detected in embryos larger than 7 millimeters.

Other criteria that indicate a miscarriage include:

• Absence of an embryo with a heartbeat at least 11 days after an ultrasound of a gestational sac with a yolk sac
• Absence of an embryo with a heartbeat at least two weeks after an ultrasound of a gestational sac with no yolk sac
  
• Gestational sac larger than 8 millimeters without a yolk sac

If You're Told You Have Miscarried

The guidelines listed above can be confusing. It's important that you understand how and why your physician has diagnosed a miscarriage. Be sure to ask any questions you have so that you are confident in and comfortable with your treatment plan. Also, give yourself grace as you process and cope with this news.

If your physician recommends treatment for a miscarriage after one ultrasound (or even after two) and you are not 100% sure that treatment is the right choice, discuss the matter with your doctor and possibly ask for a follow-up ultrasound. Most of the time 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. 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 confirmation of whether you're miscarrying can be very difficult. However, it is definitely better to be absolutely sure about your diagnosis before moving forward with treatment. Ask as many questions as you need, and expect to receive clear and compassionate answers.

For medical professionals, miscarriages are daily occurrences, but for you, they are not. 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. People go through stages of grief after​ a miscarriage and everyone responds differently. Honor yourself and grieve in the way that is best for you.