In the case of emergency outpatients, not all the diseases need to be diagnosed. Only patients who require emergency treatment need to be identified in a timely manner and entrusted to a specialist. Lower abdominal pain and genital hemorrhage account for two-thirds of the chief complaints of obstetrics and gynecology emergency outpatients, so it is important to know how to deal with these two complaints. Disorders that require emergency treatment in obstetrics and gynecology are limited. Only ectopic pregnancy, ovarian hemorrhage, twisted ovary, and pelvic inflammatory disease (PID) have required emergency surgery in our hospital. The first step of the diagnosis is a pregnancy test. A pregnancy test can rule out the disease in about half the patients. Next, ultrasonography is performed. Confirmation of the presence of intrauterine pregnancy, ovarian tumor, and intraabdominal bleeding alone is sufficient to differentiate a disorder that requires emergency treatment. Worrisome cases should be examined again after some time. Ultrasonography is a simple and noninvasive method compared with other methods. It is the most useful and indispensable method for obstetrics and gynecology emergencies.