After taking short-acting contraceptives can be judged by ultrasound without ovulation. Short-acting contraceptives mainly lead to changes in ovarian endocrine function, affecting follicular development, inhibiting ovulation, changing the endometrial environment and cervical mucus, preventing sperm from penetrating the cervix, and interfering with fertilized egg implantation to play the role of contraception. You need to take the short-acting contraceptive pills in strict accordance with the method of taking the pills, after taking a course of treatment, stopping the pills for 2 to 7 days will have menstrual flow. Regular use of the pill can inhibit ovulation. Whether ovulation has occurred after taking short-acting contraceptives can only be determined by ultrasound, through which follicular development can be observed to clarify whether there are mature follicles and ovulation. After taking the short-acting contraceptive pill, if the symptoms of the adverse reaction cannot be relieved, you need to go to the hospital in time for treatment.