Common diagnosis of acute pelvic pain

Acute pelvic pain is defined as pain of less than three months duration. Discuss a common diagnosis of acute pelvic pain in a woman of child-bearing years or a woman who is postmenopausal. How does a focused history and physical guide your work up? What labs/diagnostics would you consider? What are your differentials, including your must not miss diagnosis? Is a referral necessary based on your final diagnosis?