Try not to have intercourse before the ultrasound, as intercourse may lead to residual fluid in the vagina and may cause the woman to develop infections and other conditions that can affect the results of the ultrasound. However, it is possible to perform an ultrasound at any time in case of emergency. 1. Residual fluid: After intercourse, there may be residual fluid in the vagina, which can affect the ultrasound results. The fluid produced in the body will affect the strength of the echo of the ultrasound probe, affecting the accuracy of the examination. 2. Infection: After coitus, it may lead to changes in the pH of the female reproductive tract, which may cause infection, and the ultrasound probe needs to be put into the vagina, which may induce infection or aggravate the infection. It should be noted that before having a vaginal ultrasound, a woman should avoid the menstrual period, which is not allowed to have a vaginal ultrasound. If a woman experiences abnormal discharge, abdominal pain or fever after the examination, it is considered to be due to the occurrence of an infection. It is recommended to consult a doctor in a timely manner, and under the doctor’s guidance, complete the relevant examinations to clarify the cause of the disease and provide symptomatic treatment.