A little redness in a woman’s bottom may be caused by pregnancy-related factors, genital inflammation, genital tumors, trauma, etc. Ultrasound examination, gynecological examination and vaginal secretion examination, cervical cancer screening, etc. can be performed. 1. Pregnancy-related factors: a bit of redness in the bottom of a woman’s pants indicates vaginal bleeding, which may be caused by pregnancy-related reasons such as miscarriage, ectopic pregnancy, gravidity, uterine residue and uterine regression insufficiency, etc. Ultrasonography, blood hCG, blood routine, etc., are needed to assist in the diagnosis. 2. Genital inflammation: such as vaginitis, acute cervicitis, cervical polyps, endometrial polyps, etc. Ultrasonography, gynecological examination, hysteroscopy, vaginal secretion examination, blood routine and so on can be performed to assist diagnosis. 3. Genital tumors: such as uterine fibroids, cervical cancer, endometrial cancer, etc. Ultrasonography, gynecological examination, cervical biopsy, cervical cytology, diagnostic scraping, etc. are needed to assist diagnosis. 4. Trauma, foreign body, placement of intrauterine device, etc.: gynecological examination, ultrasonography, etc. can be used to assist diagnosis. 5. Systemic diseases: such as thrombocytopenic purpura, aplastic anemia, etc. The diagnosis can be assisted by blood routine, coagulation function, bone marrow image and other tests. 6. Ovarian endocrine dysfunction: gynecological examination, general examination, ultrasonography, luteinizing hormone, follicle-stimulating hormone, prolactin, estradiol, progesterone, hysteroscopy and other diagnostic assistance. When a woman’s bottom is a little red, she needs to go to the hospital for examination in order to find out the cause and actively treat it.