Sonography is used infrequently for diagnosing acute pelvic inflammatory disease because the physical examination is highly sensitive, because the sonogram lacks specificity, and because the patient is often scheduled for surgery or laparoscopy or treated medically based on clinical findings, obviating the need for diagnostic studies. Sonography is usually reserved for identifying, localizing, and following pelvic abscesses complicating pelvic inflammatory disease. The sonogram is valuable in identifying the location of intrauterine devices because of the increased incidence of inflammatory pelvic disease in these patients. Postoperative and posttraumatic abscesses and abscesses of gastrointestinal origin may require the concomitant use of computed tomography and radionuclide studies, with ultrasonography performing a complementary function. The ultrasound examination may be valuable both in improving diagnostic confidence and providing guidance for aspiration. Because of the limited spectrum of appearances of numerous pelvic diseases, the most accurate diagnoses are obtained when the sonogram is interpreted in light of the detailed clinical information.