molestation), urethral prolapse, vaginal infection (vaginitis), vulvar ulcers, vulvar skin conditions such as lichen sclerosus, and rarely, a tumor (benign or malignant vaginal tumors, or hormone-producing ovarian tumors). Hormonal causes include central precocious puberty, or peripheral precocious puberty (McCune–Albright syndrome), or primary hypothyroidism. While the symptom is typically alarming to parents, most causes are benign, although sexual abuse or tumor are particularly important to exclude. An examination under anesthesia (EUA) may be necessary to exclude a vaginal foreign body or tumor, although instruments designed for office hysteroscopy can sometimes be used in children with topical anesthesia for office vaginoscopy, precluding the need for sedation or general anesthesia and operating room time. Premenopausal Background In premenopausal women, bleeding can be from the uterus, from vulvar or vaginal lesions, or from the cervix. A gynecologic examination can be performed to determine the source of bleeding. Bleeding may also occur as a result of a pregnancy complication, such as a spontaneous abortion (miscarriage), ectopic pregnancy, or abnormal growth of the placenta, even if the woman is not aware of the pregnancy. This possibility must be kept in mind with regard to diagnosis and management. Generally, the causes of abnormal uterine bleeding in premenopausal women who are not pregnant include fibroids, polyps, hormonal disorders such as polycystic ovary syndrome (PCOS), blood clotting disorders, and cancer. Infections such as cervicitis or pelvic inflammatory disease (PID) can also result in vaginal bleeding. Postcoital bleeding is bleeding that occurs after sexual intercourse. Lastly, a normal and common side effect of birth control includes vaginal spotting or bleeding. Clinical guidelines (FIGO classification) A more specific clinical guideline, called the PALM-COEIN system, has been developed by FIGO (International Federation of Gynecology and Obstetrics) to classify the causes of abnormal uterine bleeding. This acronym stands for Polyp, Adenomyosis, Leiomyoma, Malignancy and Hyperplasia, Coagulopathy, Ovulatory Disorders, Endometrial Disorders, Iatrogenic Causes, and Not Classified. The FIGO Menstrual Disorders Group, with input from international experts, recommended a simplified description of abnormal bleeding that discarded imprecise terms such as menorrhagia, metrorrhagia, hypermenorrhea, and dysfunctional uterine bleeding (DUB) in favor of plain English descriptions of bleeding that describe the vaginal bleeding in terms of cycle regularity, frequency, duration, and volume. The PALM causes are related to uterine structural, anatomic, and histolopathologic causes that can be assessed with imaging techniques such as ultrasound or biopsy to view the histology of a lesion. The COEIN causes of