Miscarriage Diagnostic Tools

Ultrasound, hCG Blood Levels, and Other Tests to Diagnose Pregnancy Loss

pregnant woman in hospital bed
Image taken by Mayte Torres / Getty Images

If you are experiencing symptoms of a miscarriage, the first thing you should do is call your doctor. If you are miscarrying, your doctor will likely want to perform either quantitative hCG blood tests, ultrasound scans, fetal heart rate monitors, and possibly a pelvic exam. Your doctor will decide which test is most appropriate for your situation in order to either confirm that you are miscarrying or to allay your fears.

He or she may perform several different tests.

Diagnostic tests for miscarriage and pregnancy loss rarely offer information about the actual cause of the pregnancy loss, but because vaginal bleeding and cramping do not always mean a miscarriage, the tests will help your doctor to determine what is going on.

Quantitative hCG Blood Tests

Human chorionic gonadotropin, or hCG, is a hormone produced in your body exclusively during pregnancy. It becomes detectable in your blood about a week after ovulation when the fertilized egg implants in your uterus. In the early weeks of pregnancy, the level of hCG in your blood should double roughly every two to three days.

When you experience vaginal bleeding or spotting, your doctor will probably order two quantitative hCG blood tests, spaced roughly two to three days apart, in order to see whether your hCG level is rising or falling. When the level of hCG is rising too slowly, a miscarriage is more likely.

When the hCG level in your blood decreases over time, a miscarriage is almost certain.

The accuracy of hCG doubling times in predicting a miscarriage varies by the week in early pregnancy. In very early pregnancy, such as around the time you miss your period, hCG doubling time will be the best indicator to use because the baby is too small to view on ultrasound.

By around six weeks after your last menstrual period, hCG starts to take longer to double and the hCG doubling time becomes a little less accurate in predicting miscarriages.

Ultrasound Scans

Pregnancy ultrasounds are another common test doctors can use confirm or rule out miscarriage. Ultrasound machines use sound waves through the abdomen or vagina in order to get a rough image of the gestational sac and developing baby in your uterus. In early pregnancy until around eight weeks, most practitioners will use a transvaginal ultrasound, an ultrasound performed vaginally, rather than abdominal ultrasound in order to ensure accuracy.

During the exam, the technician will look for the baby’s heart rate and take a series of measurements of the gestational sac and the early developing baby. Your doctor will then compare the measurements to the other available information, such as your last menstrual period and hCG levels, in order to diagnose whether or not you are miscarrying.

With a transvaginal ultrasound, the baby’s heartbeat normally becomes visible around six weeks after your last menstrual period. If the heartbeat is not visible at this time, your doctor may ask you to come back for another scan in a few days or a week.

This may feel frustrating and the waiting time may be hard, but waiting for another scan will help your doctor to be absolutely sure before diagnosing a miscarriage. Sometimes you may not ovulate exactly on the day that the traditional menstrual cycle predicts, and in early pregnancy, being off by even a few days may make a difference in whether you can see the baby’s heartbeat on the ultrasound scan or not.

If the baby’s heartbeat was visible on a previous ultrasound scan and then is not visible on a subsequent one, then you have likely miscarried.

Fetal Heart Rate Monitors

Fetal heart rate monitors, sometimes called fetal dopplers, are miniature ultrasound devices that detect the sound of your baby’s heartbeat through your abdomen but do not provide any images.

The heartbeat becomes audible on a fetal heart rate monitor somewhere between seven and twelve weeks, but the exact time varies from person to person based on factors such as the position of the uterus and position of the placenta.

Most doctors use fetal heart rate monitors as a part of routine prenatal care after the first trimester. Many doctors will not use heart rate monitors any earlier than that in order to prevent women from becoming unnecessarily worried if, for example, the monitor does not pick up the heartbeat at eight weeks. (For that particular woman, it may simply be too early to hear anything through the monitor.)

For a woman in the late first trimester with concerns about miscarriage, doctors may use a heart rate monitor as a quick screening device before ordering further testing, because if the heart rate is audible, miscarriage is much less likely – but not hearing the heart rate is not a definitive sign of pregnancy loss.

If you are more than twelve weeks pregnant and your doctor cannot find the baby’s heart rate on the monitor, your doctor may send you for a full ultrasound scan to rule out miscarriage.

Pelvic Exams

If you go to your doctor with concerns about miscarriage, he may perform a pelvic exam in order to check whether your cervix is dilated. Cervical dilation means a greater likelihood of miscarriage and your doctor will want you to do further testing. During a pelvic exam, your doctors can also look for indicators of an ectopic pregnancy.

If you are having spotting or light vaginal bleeding and your cervix is not dilated, your doctor may send you home to wait and see if the bleeding stops. Spotting in early pregnancy is common and, depending on your circumstances, your doctor may want to hold off on ordering further testing unless the bleeding continues.

Support After a Miscarriage

If you are miscarrying, it is totally normal to be upset and to grieve. You may want to look for a support group to help you get through the experience. Know that miscarriage causes are rarely related to anything you did and most losses are random, one-time occurrences.

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