Indications 1. Infertility with no abnormality in the husband’s semen examination, patient with biphasic BBT and good luteal function for 3 consecutive menstrual cycles, but still unable to conceive. 2.Patients with history of lower abdominal surgery such as appendectomy, cesarean operation; history of pelvic inflammatory disease such as gonorrhea infection, puerperal infection; history of chronic appendicitis or peritonitis, now suffering from endometriosis, etc., who are treated for infertility and suspected to have tubal obstruction. 3.Observation of uterine cavity morphology to determine the presence of uterine malformation and its type, the presence of uterine cavity adhesions, submucosal fibroids, endometrial polyps and foreign bodies, etc. 4. Laparoscopic examination of extra-luminal adhesions of the fallopian tubes and preoperative examination when tubal plastic surgery is proposed, as HSG can further provide information on the luminal situation of the fallopian tubes. Preparation for imaging 1. Time of imaging 3-7 days after menstruation, i.e. before ovulation. 2.No acute or subacute pelvic inflammatory disease, such as no inflammatory mass or pressure pain at both adnexa, and body temperature below 37,5℃. 3.Leukostasis suspension examination shows no trichomonas or mycobacterial infection in the vagina. 4. Avoid sexual intercourse and deep bathing for 3 weeks before and 2 weeks after the imaging to prevent infection.