It can sometimes be difficult to determine if bleeding is from a miscarriage or a period, especially if it has happened within 4 weeks of an expected period.

Therefore, if you notice abnormal vaginal bleeding, you should consult your gynecologist for assessment. The doctor may order a beta-hCG blood test as well as a transvaginal ultrasound to rule out the possibility of an ectopic pregnancy or miscarriage.

Ongoing monitoring is essential in the presence of moderate vaginal bleeding and a suspected miscarriage or period, as monitoring allows for the prevention of complications, like iron deficiency anemia caused by excessive bleeding, and initiate the most appropriate treatment, if necessary.

Difference between a miscarriage or period

The following table outlines the main differences between period bleeding and miscarriage bleeding. However, it is important to take into account that the signs and symptoms of menstruation vary greatly from one woman to another.

	Late period	Miscarriage
Color	Bleeding is slightly brown-red, similar to previous periods	Bleeding is slightly brown, and then changes to pink or bright red. May be accompanied by foul odor.
Amount	A pad or tampon is able to absorb the amount	Difficut to contain bleeding in a pad or tampo
Clots	Small clots may be needed	Large clots and grey tissue may be noted. In some cases, you may identify an amniotic sac
Pain and cramps	Mild pain and cramps in the abdomen, thighs or back that improve with menstruation	Very intense pain that emerges suddenly, followed by abundant bleeding
Fever	Rarely occurs with a period	May emerge, due to uterine inflammation

Some women may experience very little pain during their period, while others experience severe cramps and bleed a lot, making this characteristic less reliable for some to distinguish a period or miscarriage. Therefore, you are advised to consult a doctor if your period presents differently from previous ones, so that appropriate tests can be carried out and the best treatment can be initiated.

Read more about period symptoms and signs that it may be coming.

Possible tests

A pharmacy pregnancy test can, in some cases, help identify whether you are experiencing a miscarriage or a period. However, the most reliable way to confirm a diagnosis is through a transvaginal ultrasound or a blood test to evaluate the amount of beta-hCG hormone circulating in the blood, which will be present during pregnancy.

Quantitative beta-HCG test

The beta-HCG test needs to be done on at least two different days to assess whether the levels of this hormone in the blood are decreasing. If this happens, it is a sign of a miscarriage.

However, if the values increase, it is a sign that the pregnancy may still be viable, and that the bleeding may have occurred due to implantation. An ultrasound may be ordered in this case to further assess.

If the values remain the same and are below 5mIU/ml, it is likely that there was no pregnancy and, therefore, the bleeding is related to menstruation.

Transvaginal ultrasound

Transvaginal ultrasound is ordered to obtain an image of the inside of the uterus and a woman's other reproductive structures, such as the fallopian tubes and ovaries. With this exam, the doctor can identify whether there is an embryo developing in the uterus, as well as evaluate other problems that may have caused the bleeding, such as an ectopic pregnancy.

In some rarer cases, the ultrasound may indicate that the woman does not have a visible embryo or any other obvious changes in the uterus, even when the beta-HCG values are altered. In these cases, the woman may be pregnant and, therefore, it is recommended to repeat the examination approximately 2 weeks later, to assess whether it is now possible to identify the embryo.

What to do if you suspect a miscarriage

In most cases, a miscarriage occurs within the first week of pregnancy and, therefore, the bleeding only lasts 2 or 3 days. Symptoms tend to improve during this time, meaning there is no need to go to the gynecologist.

However, when the pain is severe or the bleeding is very heavy and causes tiredness and dizziness, you should see a gynecologist or proceed to a hospital to start treatment.