Is it harmful not to have semen enter the vagina during menstruation?

Patient's question:

During menstruation, have sex

Doctor's answer:

The denuded surface of the endometrium during menstruation has dilated blood sinuses and blood clots, which are excellent breeding environments for bacteria. If sexual intercourse occurs during menstruation or unclean menstrual pads are used, bacteria can invade, leading to inflammation and gynecological diseases. In severe cases, it can cause infertility. However, this is not something that happens to everyone and is related to factors such as your resistance, the number of pathogens, their invasive power, and toxicity, as well as other underlying causes.
Recommendation: Dysuria and urinary urgency are primarily seen in urinary tract infections such as urethritis and cystitis. It is necessary to undergo a routine urinalysis at the hospital for diagnosis and then receive targeted treatment.