Difference Between Blood Clots and Miscarriage

Both blood clots and miscarriage present as vaginal bleeding and lower abdominal pain. Both conditions are common in women, in the reproductive age group. But blood clots can accumulate in the uterus after a miscarriage, as well. Clinical history, examination and investigations are essential to differentiate between the two.


Miscarriage is defined medically as the expulsion or threat at expulsion of products of conception less than 500g of weight or before 28 weeks of gestation. There are many types of miscarriages.  Missed miscarriage, complete miscarriage, incomplete miscarriage, and threatened miscarriage. Missed miscarriage presents as an incidental finding during routine antenatal scanning. There are no symptoms and signs at all. Ultra sound shows no fetal heart beat. Gynecologist may opt to wait for spontaneous onset of labor or may dilate the cervix with prostaglandins.  If products do not come out completely, surgical dilatation and evacuation may be necessary. A second pregnancy is best avoided for three months till the cycle get regular.

Incomplete miscarriage presents with lower abdominal pain and vaginal bleeding preceded by a period of amenorrhea. There may be heavy vaginal bleeding due to the open cervix. Urgent diagnosis and treatment is necessary. Vaginal examination reveals a dilated cervix, open os and enlarged uterus. Ultra sound scan shows no fetal heart beat, products and blood clots. Dilatation of the cervix and evacuation is the treatment of choice.    

Complete miscarriages present similar to incomplete miscarriage with less vaginal bleeding. Dilatation and evacuation is the treatment of choice. Vaginal examination may show a closed os, enlarged uterus and mild vaginal bleeding. Ultra sound examination shows blood clots only.

Threatened miscarriage presents as lower abdominal pain and vaginal bleeding after a period of amenorrhea. Vaginal examination shows an enlarged uterus and closed cervix. Ultra sound scan shows fetal heart beat. Observation and progesterone therapy are the treatment methods.

Blood Clots

Blood clots can pass per vagina due to abnormal bleeding from inside the uterus due to miscarriage. After dilatation and evacuation there is a mild bleed from the vessels of the endometrium. Blood collects inside the uterus if the os is closed. These blood clots pass without incident in most cases. However, in some patients, infections can get into the uterus and cause endometritis.  Blood clots result due to heavy menstruation, as well. When there is excessive menstrual bleeding, blood passes as clots. Ultra sound scan shows a thick endometrial shadow. Antifibrinolytic drugs and pain killers are in the first line of treatment. Norethisterone may be used if the first line is not effective.

What is the difference between Blood Clots and Miscarriage?

• Blood clots pass in miscarriages, as well as menorrhagia.

• Blood clots are uniform red clumps of blood while miscarriage puts out tissue parts.

• The external os is closed in heavy menstruation, complete miscarriage, and threatened miscarriage. The external os is open in incomplete miscarriage.

• Ultra sound scan shows blood clots as black areas while products of conception as white areas.

• No fetal heart is identifiable in complete, incomplete, and missed miscarriages, as well as in menorrhagia. Fetal heart is present in threatened miscarriage.

• Antifibrinolytics are contraindicated in pregnancy while indicated in heavy menstruation.


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