Pelvic pain: lessons from anatomy and physiology. Pelvic pain is often a difficult differential diagnosis in the emergency department. For physiologic reasons, pain in the pelvis is difficult to localize to a specific organ, and pelvic peritonitis is hard to recognize. On the other hand, differences in types of pain can be very useful in arriving at a correct diagnosis. The clinician must learn to recognize superficial and deep somatic pain, and differentiate between various types of visceral pain which originate from inflammation, ischemia, or colic. A review of the anatomy and physiology of pelvic pain helps identify some of the problems as well as potential aids in approaching the patient with pelvic pain. 