How to Distinguish Between Pregnancy Bleeding and Menstrual Flow - Obstetrics and Gynecology

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How to distinguish between pregnancy bleeding and menstruation?


My girlfriend's period was two weeks late, so she went to see a doctor.
The doctor performed a pregnancy test which came back negative, and an ultrasound was also done with no findings.
She was prescribed medication to induce her period, which she took for about five days.
After three days of taking the medication, her period started and lasted for about six days.
However, today she told me that she vomited around noon.
When I asked her if she frequently feels the need to urinate, she said yes, but she can't seem to urinate much.

I want to know if what she experienced before was actually her period, or if it could have been implantation bleeding.
The pregnancy test should have been quite accurate, and she also had an ultrasound.
Is there a possibility of error in those tests? Additionally, can pregnancy cause frequent urination? I thought that would occur due to the growing uterus pressing on the bladder, but her abdomen seems the same size.
Also, frequent urination should involve a significant amount of urine, not just a drop or two.

How can we distinguish between a menstrual period and implantation bleeding? I would appreciate your help in clarifying this.

LEO, 20~29 year old female. Ask Date: 2006/09/25

Dr. Dai Qihan reply Obstetrics and Gynecology


If you have any concerns, please visit the outpatient clinic for an examination.

Reply Date: 2006/09/25

More Info


Distinguishing between pregnancy bleeding and menstrual flow can be quite challenging, especially for those who are trying to conceive or are concerned about their reproductive health. Your girlfriend's situation raises several important points that we can address.

Firstly, it is essential to understand the typical characteristics of menstrual bleeding versus pregnancy-related bleeding. Menstrual bleeding usually occurs in a predictable cycle, typically lasting between 3 to 7 days, and is often accompanied by other symptoms such as cramps, mood swings, and breast tenderness. The flow can vary from light to heavy, and it may include blood clots. In contrast, pregnancy bleeding can manifest in various ways, including light spotting, which may be pink or brown rather than the bright red of menstrual blood. This type of bleeding can occur around the time of implantation, which is when the fertilized egg attaches to the uterine lining, or it may occur later in pregnancy due to other factors.

In your girlfriend's case, the fact that she experienced a late period and was subsequently tested for pregnancy is significant. A negative pregnancy test, especially when combined with an ultrasound that shows no signs of pregnancy, typically indicates that she is not pregnant. However, false negatives can occur, particularly if the test is taken too early or if there are issues with the test itself. Additionally, some women experience what is known as a chemical pregnancy, where a fertilized egg implants but does not develop properly, leading to a very early miscarriage that may be mistaken for a late period.

Regarding her symptoms of nausea and frequent urination, these can indeed be signs of early pregnancy, but they can also be attributed to other factors, such as hormonal changes or even stress. Frequent urination in early pregnancy is often due to hormonal changes that increase blood flow to the kidneys, leading to increased urine production. However, if she is experiencing only a few drops of urine, this could indicate a urinary tract infection (UTI) or other issues unrelated to pregnancy.

To summarize, the best way to distinguish between menstrual bleeding and pregnancy bleeding is through a combination of factors: the timing of the bleeding, the characteristics of the blood, and the presence of other symptoms. If there is any doubt, it is advisable for your girlfriend to consult with a healthcare provider for further evaluation. They may recommend additional testing, such as a blood test for pregnancy, which can detect lower levels of the hormone hCG than urine tests, or a follow-up ultrasound to monitor any changes.

In conclusion, while your girlfriend's situation appears to lean towards a late menstrual cycle rather than pregnancy, it is crucial to remain vigilant about her symptoms and seek medical advice if there are any concerns. Understanding the nuances of menstrual and pregnancy-related bleeding can help in making informed decisions about reproductive health.

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Dr. Cao Guotao reply Obstetrics and Gynecology
Hello, it might look like menstruation. If you're unsure, taking a pregnancy test will clarify. Wishing you good health.

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