The next day after coitus, the small abdominal swelling is mainly due to pelvic congestion, the most common cause is due to pelvic inflammatory disease or cervicitis. Reproductive system infections can lead to pelvic congestion, edema, pelvic fluid, need to pay attention to the observation of vaginal secretions, sexual intercourse with or without contact bleeding and abdominal pain caused by the less common abdominal swelling after sex, due to the occurrence of intense sexual intercourse will lead to local damage to the vagina, stimulation of local nerves will lead to discomfort in the abdomen, can be temporarily observed, if accompanied by discomfort or longer duration of the need to consult a doctor. If the discomfort is accompanied by or lasts for a long time, you need to consult a doctor in time to avoid pelvic inflammatory disease, long-term chronic inflammation can easily lead to local adhesions.