Diagnostic Approach for Suspected Endometriosis, Pelvic Mass, or PID

Initial Clinical Assessment

The Centers for Disease Control and Prevention recommends a "low threshold for diagnosis" of PID to prevent reproductive sequelae, accepting that this approach has lower specificity, with minimum diagnostic criteria including lower abdominal tenderness, bilateral adnexal tenderness, and cervical motion tenderness 1, 2, 3
Fever >38.3°C, abnormal cervical/vaginal discharge, and elevated ESR or CRP increase diagnostic specificity for PID 1, 3
Recent sexual activity or new partner increases suspicion for PID 1
Cyclic pelvic pain patterns, such as dysmenorrhea, dyspareunia, dyschezia, dysuria, or chronic pelvic pain, are characteristic of endometriosis 4
Infertility is present in approximately 50% of endometriosis cases 4
A palpable mass or pressure symptoms may indicate a pelvic mass, with irregular bleeding or postmenopausal bleeding raising concern for malignancy 5

For PID, immediate laboratory testing should include cervical cultures for N. gonorrhoeae and C. trachomatis, as well as a pregnancy test to exclude ectopic pregnancy 1, 3
Empiric treatment for PID should be initiated immediately based on minimum clinical criteria, without waiting for imaging or culture results, using ceftriaxone plus doxycycline with or without metronidazole 1, 3
For endometriosis, transvaginal ultrasound with an expanded protocol is the initial imaging modality of choice, with MRI pelvis without IV contrast sufficient for detecting deep infiltrating endometriosis 4, 6
CA-125 has no clinical utility for the diagnosis of endometriosis, but may be helpful for monitoring clinical response in confirmed extrauterine disease 4
For a pelvic mass, transvaginal ultrasound should be used to characterize the mass, with MRI pelvis with IV contrast if ultrasound is inconclusive or to differentiate benign from malignant features 5, 6

The American College of Radiology recommends against using CT pelvis for standard endometriosis diagnosis, as it has no role in this setting 6
The National Comprehensive Cancer Network recommends surgical staging if malignancy is suspected in a pelvic mass 5
Inpatient treatment is indicated for clinically severe PID, pregnancy, HIV infection, no response to oral medication, or tubo-ovarian abscess 3