What is the appropriate workup for a patient presenting with pelvic pain?

Workup for Pelvic Pain

The initial workup for pelvic pain must begin with serum β-hCG testing in all reproductive-age women, followed by ultrasound as first-line imaging for suspected gynecologic causes or CT abdomen/pelvis with IV contrast when non-gynecologic etiologies are more likely. 1

Immediate Laboratory Assessment

• Obtain serum β-hCG in all reproductive-age women presenting with pelvic pain, as this single test fundamentally alters the diagnostic pathway and becomes positive ~9 days post-conception 1
• A positive β-hCG immediately prioritizes pregnancy-related causes (ectopic pregnancy, spontaneous abortion, placental abruption) and eliminates CT as first-line imaging due to fetal radiation exposure 1
• Obtain urine culture even with negative urinalysis, as clinically significant bacteria may not be identifiable on dipstick testing 1, 2

Critical Clinical History Elements

• Document pain characteristics: number of voids per day, constant urge sensation, exact pain location/character/severity (0-10 scale), relationship to menstruation or ejaculation 1, 2
• Assess associated symptoms: dyspareunia, dysuria, ejaculatory pain, nausea, vomiting, fever, bowel symptoms to distinguish gynecological from non-gynecological etiologies 1, 2
• Determine pain duration: acute (<3 months) versus chronic (≥6 months), as this fundamentally changes the diagnostic approach 3, 1
• Perform brief neurological examination and assess for incomplete bladder emptying via post-void residual to rule out occult neurologic problems and retention 1, 2

Imaging Algorithm Based on Clinical Suspicion

For Reproductive-Age Women with Suspected Gynecologic Causes:

• Transvaginal and transabdominal pelvic ultrasound with Doppler is the initial imaging modality of choice, providing excellent visualization of ovarian cysts, ovarian torsion, pelvic inflammatory disease, and ectopic pregnancy without radiation exposure 1, 4
• If β-hCG is positive, ultrasound is mandatory as first-line imaging and CT is contraindicated due to fetal radiation exposure 1
• Ultrasound has 98% sensitivity and 100% specificity for rectosigmoid and retrocervical endometriosis 4
• Thick tubal wall and "cogwheel" sign on ultrasound are 100% and 86% sensitive for acute pelvic inflammatory disease, respectively 4
• Tubo-ovarian abscess has 93% sensitivity and 98% specificity on pelvic ultrasound 4
• MRI pelvis without and with IV contrast is appropriate for equivocal ultrasound findings, particularly for detecting endometriosis and characterizing complex adnexal masses 4

For Postmenopausal Women:

• CT abdomen/pelvis with IV contrast is appropriate as first-line imaging when clinical presentation is nonspecific or includes both gynecologic and non-gynecologic differentials 3
• In postmenopausal women, ovarian cysts account for one-third of gynecologic pain, uterine fibroids are the second most common cause, pelvic infection accounts for 20%, and ovarian neoplasm accounts for 8% 3
• Ultrasound remains appropriate when gynecologic etiology is strongly suspected based on clinical presentation 3

For Non-Gynecologic Causes (Any Age):

• CT abdomen/pelvis with IV contrast should be the initial study when non-gynecological causes are strongly suspected, providing ~88% overall accuracy compared with surgical diagnosis 3, 1
• CT has 89% sensitivity versus 70% for ultrasound in urgent abdominopelvic diagnoses 3, 1
• CT is superior for detecting appendicitis (94% sensitivity, 94% specificity), diverticulitis, inflammatory bowel disease, urinary calculi, and pyelonephritis 1, 2

For Males with Pelvic Pain:

• Start with transabdominal ultrasound of abdomen and pelvis for suspected urological causes, which has 75% accuracy for predicting ureteral stones and 97.2% sensitivity for renal stones using twinkle artifact on color Doppler 2
• Normal renal ultrasound predicts no need for urological intervention in 90 days, allowing conservative management 2
• Proceed directly to CT abdomen/pelvis with IV contrast for suspected gastrointestinal causes 2

Key Differential Diagnoses by System

Gynecological/Obstetrical (Reproductive-Age Women):

• Hemorrhagic ovarian cysts, ovarian torsion, pelvic inflammatory disease, ectopic pregnancy, spontaneous abortion, placental abruption 1
• Endometriosis (secondary dysmenorrhea), tubo-ovarian abscess 4

Gynecological (Postmenopausal Women):

• Ovarian cysts (33% of cases), uterine fibroids with torsion/necrosis/infarction (second most common), pelvic infection (20%), ovarian neoplasm (8%) 3

Non-Gynecological:

• Appendicitis, inflammatory bowel disease, infectious enteritis, diverticulitis, urinary tract calculi, pyelonephritis, pelvic thrombophlebitis 1, 2

Chronic Pain-Specific (≥6 months):

• Pelvic congestion syndrome, intraperitoneal adhesions, hydrosalpinx, chronic inflammatory disease, cervical stenosis, interstitial cystitis/bladder pain syndrome 3, 1

Critical Pitfalls to Avoid

• Never rely on plain radiographs for pelvic pain evaluation, as they have extremely limited utility 1, 2, 4
• Do not skip β-hCG testing in reproductive-age women, as inadvertent CT in pregnant patients exposes the fetus to unnecessary radiation 1
• Starting with CT instead of ultrasound in reproductive-aged women with suspected gynecologic causes exposes patients to unnecessary radiation 4
• Do not overlook vascular causes (pelvic congestion syndrome, thrombophlebitis) that may require specific Doppler protocols 1
• Perform proper hematuria workup in patients with unexplained hematuria or tobacco exposure, given high bladder cancer risk in smokers 1
• Consider cystoscopy only when Hunner lesions are suspected or to exclude bladder cancer, stones, or foreign bodies—not as routine evaluation 1, 2

Special Pregnancy Considerations

• Gadolinium-based MRI contrast is pregnancy category C and should be administered only if potential benefit outweighs risk, as gadolinium is excreted in amniotic fluid and remains for indeterminate periods 1
• Elevated β-hCG in non-pregnant patients may indicate miscarriage, ectopic pregnancy, pituitary production, paraneoplastic production, or gestational trophoblastic disease 1