Epidemiology

Acute pain caused by pelvic pathology is common, and the presenting complaint may be diffuse or lower abdominal pain, pelvic pain, or low back pain. A patient with chronic pelvic pain may also have an acute process, either related to the chronic condition or arising de novo.

Over one third of reproductive-age women will experience nonmenstrual pelvic pain. Among diagnoses for women with pain caused by gynecologic disorders in the emergency department, pelvic inflammatory disease (PID) and lower genital tract infections (e.g., cervicitis, candidiasis, Bartholin’s abscess) account for almost half. Other common diagnoses are menstrual disorders, noninflammatory ovarian and tubal pathology (including cysts and torsion), and ectopic pregnancy. In the general population, ectopic pregnancy accounts for 2% of first-trimester pregnancies; however, among women visiting the emergency department with vaginal bleeding or abdominal pain in the first trimester of pregnancy, the incidence of ectopic pregnancy is as high as 18%.¹

Younger patients and those with multiple sexual partners are more likely to have PID, and a previous episode increases the likelihood of a subsequent episode.² The risk of ectopic pregnancy is higher in women who have had PID, pelvic surgery, or a prior ectopic pregnancy, as well as in women with an intrauterine device. Heterotopic pregnancy is of special concern in women undergoing fertility treatment. The incidence of heterotopic pregnancy in the general population was 1 in 30,000 patients in 1948 and is currently reported to be as high as 1 in 8000. It is much more common in women undergoing assisted reproductive techniques (in vitro fertilization and ovulation-stimulating medications), with an incidence of 1 in 100.³ Common nongynecologic diseases, such as appendicitis, diverticulitis, urinary tract infection, and urolithiasis, remain important considerations in the woman with acute pelvic pain. Box 33-1 lists conditions accounting for pelvic pain in most women.

Some causes of pelvic pain may lead to serious sequelae. PID carries the short-term risk of tubo-ovarian abscess and the long-term risks of impaired fertility, chronic pelvic pain, and increased predisposition to ectopic pregnancy.⁵ Rupture of an ectopic pregnancy or a hemorrhagic ovarian cyst may be life-threatening. Unrecognized abuse may have serious or lethal consequences as well.

Pathophysiology

The female pelvis contains the vagina, uterus, fallopian tubes and ovaries, ureters and urinary bladder, and sigmoid colon and rectum, as well as components of the vascular and musculoskeletal systems. Although pelvic pain often originates from the reproductive organs, it may arise from any structures that lie adjacent to or course through the pelvis. Visceral pain afferents supplying the pelvic organs have common innervation with the appendix, ureters, and colon. Their significant overlap makes accurate localization difficult for both patient and clinician. Pain may be initiated by inflammation, distention, or ischemia of an organ or by spillage of blood, pus, or other material into the pelvis. Parietal pain develops when the afferent nerves in the parietal peritoneum adjacent to an affected organ are stimulated.

Differential Considerations

The differential diagnosis of pelvic pain is broad (see Box 33-1). Most causes of pelvic pain fit into three categories: (1) the reproductive tract, (2) the urinary tract, and (3) the intestinal tract. Because a subset of pelvic pain is found only in pregnancy, the pregnancy test is a key branch point in the diagnostic process. Potential pregnancy-related disorders can be divided into complications of early pregnancy and complications that occur further along in pregnancy. Although the specific cause of pelvic pain cannot always be determined at the initial ED visit, an organized approach usually leads to the confirmation or exclusion of disorders most likely to result in significant morbidity and/or mortality.

Pivotal Findings

It is rare that any particular finding on history or physical examination (summarized in Table 33-1) is reliable enough to conclusively make or exclude a particular diagnosis, so ancillary testing (beyond a simple pregnancy test) is commonly required in the evaluation of patients with acute pelvic pain.