Blood in urine after menstruation

In life, many people often encounter some problems about menstruation, such as bleeding in urine after menstruation. This can be considered not to be related to menstruation, because menstruation originally flows out through the vaginal opening, and urine is discharged through the urethra. There is a big difference between the two. Bleeding in urine can be considered to be red blood cells in the urine, and it is necessary to check to see if it is a problem with kidney function.

To understand urine occult blood, you must first understand urine routine. Urinalysis is the most common examination item in the hospital. Generally, the doctor will write an application form for urinalysis, and the patient will take some urine and send it to the laboratory, and the results will come out quickly. Urinalysis mainly includes urine specific gravity, uric acid alkalinity, urine protein, urine white blood cells, urine nitrate, urine occult blood, urine red blood cells, etc. It can be seen that urine occult blood is an item in urine routine test.

Urine occult blood, to put it simply, is a chemical reaction. When testing in the laboratory, a dry chemical method called "hemoglobin peroxidase method" is used, with a sensitivity of 150-300 micrograms/liter. We know that the main component of red blood cells is hemoglobin. If there is hemoglobin in the urine, a chemical reaction will occur in the experiment. That is to say, our occult blood in the urine is called positive, or several "+" signs. This means there may be red blood cells in the urine. Why do we say that there may be red blood cells in urine, but not that there must be red blood cells? There are two main reasons:

First, the target of urine occult blood detection is hemoglobin in urine. Although hemoglobin is the main component of red blood cells, it is not equal to red blood cells after all. For example, some reasons may cause the red blood cells in the blood to dissolve and be destroyed, releasing a large amount of hemoglobin. The hemoglobin will then pass through the kidneys and be excreted from the urine. If a routine urine test is done at this time, the urine occult blood will be found to be positive, with multiple "+" signs for occult blood in the urine. However, this does not mean that there is blood or red blood cells in our urine.

Second, the target of urine occult blood test is not just hemoglobin in urine. In addition to hemoglobin in urine, the targets of urine occult blood detection also include myoglobin, heat-labile enzymes, many oxidants, bacteria, etc. Therefore, when the urine contains these components, the urine occult blood is also positive, and there are also several "+" signs. Obviously, the positive urine occult blood at this time is definitely not the presence of blood or red blood cells in the urine. In medicine, it is called a false positive result.

I don’t know if you have noticed that in addition to occult blood in urine, there is also an item called red blood cells in urine in routine urine tests. This shows that urine occult blood and urine red blood cells are not the same concept, but two different things.

Urine occult blood is a chemical reaction. It is only a reference for us to diagnose whether there is hematuria or whether there are red blood cells in the urine.

The red blood cells in urine are seen by doctors with the naked eye under a microscope. It is not a chemical reaction. The number of red blood cells is the number that is seen. Whether there is blood in the urine or whether there are red blood cells in the urine can be determined mainly by looking at the urine red blood cells item in the routine urine test. Healthy people also have red blood cells in their urine, but the number does not exceed 3 per high-power field of view. If the number of red blood cells in urine is greater than 3/high-power field of view, it can basically be said to be hematuria, but occult blood in urine is often not "blood".

In short, occult blood in urine is not the same as hematuria or blood in the urine. You must find an experienced doctor to take a closer look.