How to evaluate and manage a patient with acute pelvic pain, considering demographics, medical history, and potential underlying conditions such as ectopic pregnancy or ovarian torsion?

How to Clerk a Patient with Acute Pelvic Pain

Immediate First Step: Pregnancy Testing

In all reproductive-age women presenting with acute pelvic pain, obtain a serum beta-hCG test immediately—this single test fundamentally determines your entire diagnostic pathway and imaging strategy. 1, 2 A negative serum beta-hCG essentially excludes intrauterine or ectopic pregnancy (becomes positive ~9 days post-conception), while a positive result immediately prioritizes pregnancy-related emergencies like ectopic pregnancy and eliminates CT as a first-line option due to fetal radiation exposure. 1, 2

Critical History Components

Pain Characteristics

• Onset and duration: Acute pelvic pain is defined as pain lasting <3 months; document exact timeline to distinguish from chronic pain (≥6 months). 1, 3
• Location and radiation: Poorly localized pain suggests broader differential including non-gynecologic causes; well-localized pain may point to specific organ pathology. 1, 2
• Character and severity: Sharp, sudden pain suggests torsion or rupture; cramping suggests uterine/bowel origin. 3, 4
• Relationship to menstruation: Cyclic vs. non-cyclic pain patterns help distinguish endometriosis from other causes. 2, 5

Associated Symptoms That Change Management

• Vaginal bleeding: Raises concern for ectopic pregnancy, spontaneous abortion, or placental abruption in pregnant patients. 6, 7
• Fever: Suggests pelvic inflammatory disease, tubo-ovarian abscess, appendicitis, or pyelonephritis. 1, 6, 2
• Nausea/vomiting: Common but nonspecific; seen in appendicitis, ovarian torsion, and ectopic pregnancy. 1, 3
• Dysuria and urinary frequency: Points toward urinary tract infection, pyelonephritis, or urinary calculi. 2, 3
• Dyspareunia: Suggests pelvic inflammatory disease, endometriosis, or pelvic floor dysfunction. 2, 5

Age-Specific Differential Considerations

• Reproductive-age women: Ectopic pregnancy (occurs in up to 13% of symptomatic ED patients), ovarian torsion, hemorrhagic ovarian cysts, and pelvic inflammatory disease are most common. 1, 7, 3
• Postmenopausal women: Ovarian cysts (33% of cases), uterine fibroids (second most common), pelvic infection (20%), and ovarian neoplasm (8%) predominate; cancer must always be considered. 1, 4

Physical Examination Priorities

• Vital signs assessment: Check blood pressure and pulse to identify hemodynamic instability suggesting ruptured ectopic pregnancy or hemorrhagic ovarian cyst. 7, 3
• Abdominal examination: Assess for peritoneal signs (guarding, rebound tenderness) indicating surgical emergency; check for Murphy's sign if right upper quadrant involvement. 1, 3
• Pelvic examination: Evaluate for cervical motion tenderness (pelvic inflammatory disease), adnexal masses or tenderness (ovarian pathology), and uterine size/tenderness. 3, 5
• Brief neurological exam: Rule out occult neurologic problems that may present as pelvic pain. 2, 5

Laboratory Testing Algorithm

Essential Tests

• Serum beta-hCG: Mandatory in all reproductive-age women before any imaging decisions. 1, 6, 2
• Complete blood count: Leukocytosis suggests infection or inflammation (appendicitis, pelvic inflammatory disease). 1, 3
• Urinalysis and urine culture: Obtain culture even with negative urinalysis to detect clinically significant bacteria not identifiable on dipstick. 2, 3

Additional Tests Based on Clinical Suspicion

• Serial beta-hCG monitoring: If ultrasound is indeterminate, follow-up in 2-7 days to assess for appropriate rise and exclude ectopic pregnancy. 7, 4
• Sexually transmitted infection testing: Approximately 15% of untreated chlamydia infections lead to pelvic inflammatory disease. 3

Imaging Strategy: A Decision Tree Approach

If Beta-hCG Positive (Pregnant Patient)

Ultrasound of abdomen and pelvis (both transabdominal and transvaginal) is mandatory as first-line imaging; CT is contraindicated due to fetal radiation exposure. 1, 6, 2 Transvaginal ultrasound has pooled sensitivity of 99.3% for detecting ectopic pregnancy when no intrauterine pregnancy is visualized. 7 If ultrasound is indeterminate, MRI abdomen/pelvis without IV contrast is preferred over CT, with 100% sensitivity and 93.6% specificity for appendicitis in pregnant patients. 6

If Beta-hCG Negative and Gynecologic Etiology Suspected

Ultrasound (transvaginal and transabdominal) is the initial imaging modality of choice, providing excellent visualization of ovarian cysts, ovarian torsion, pelvic inflammatory disease without radiation exposure. 1, 2 Doppler imaging should be considered a standard component of pelvic ultrasound. 6 Ultrasound findings for tubo-ovarian abscess include thick-walled fluid collection with septations and irregular margins. 6

If Non-Gynecologic Etiology Suspected or Broad Differential

CT abdomen/pelvis with IV contrast should be the initial study, providing ~88% overall accuracy compared with surgical diagnosis and 89% sensitivity versus 70% for ultrasound in urgent abdominopelvic diagnoses. 1, 2 CT is superior for detecting appendicitis, diverticulitis, inflammatory bowel disease, urinary calculi, and pyelonephritis. 1, 2 CT is particularly useful when pain is poorly localized or when there is concern for masses, organomegaly, or vascular pathology. 1

If Initial Imaging is Nondiagnostic

• For pregnant patients: MRI without contrast is the next step; gadolinium should be avoided unless absolutely necessary (pregnancy category C). 6, 2
• For non-pregnant patients: MRI can be helpful if ultrasound and CT are nondiagnostic. 1, 4

Age-Specific Etiologies and Their Frequencies

Reproductive-Age Women (Beta-hCG Negative)

• Most common gynecologic causes: Hemorrhagic ovarian cysts, pelvic inflammatory disease, ovarian torsion, endometriosis. 1, 3, 4
• Most common non-gynecologic causes: Appendicitis, inflammatory bowel disease, urinary tract calculi, pyelonephritis. 1, 2

Postmenopausal Women

• Ovarian cysts: Account for 33% of gynecologic pain cases. 1
• Uterine fibroids: Second most common cause; pain from torsion of pedunculated fibroids, prolapse of submucosal fibroid, or acute infarction/hemorrhage. 1
• Pelvic infection: 20% of cases, including tubo-ovarian abscess related to sexual activity or recent instrumentation. 1
• Ovarian neoplasm: 8% of cases; malignancy must always be considered in this age group. 1

Critical Pitfalls to Avoid

• Never skip beta-hCG testing in reproductive-age women: Inadvertent CT in pregnant patients exposes the fetus to unnecessary radiation. 1, 2
• Do not assume all early pregnancy pelvic pain is benign: Approximately 40% of ectopic pregnancies are misdiagnosed at the presenting visit; maintain high suspicion even with mild symptoms. 7, 3
• Never rely on plain radiographs: They have extremely limited diagnostic value in acute pelvic pain evaluation. 1, 2
• Do not overlook vascular causes: Pelvic congestion syndrome and thrombophlebitis may require specific Doppler protocols. 2
• Avoid overreliance on laboratory values without clinical correlation: Leukocytosis is nonspecific and must be interpreted with clinical presentation. 1, 6

Management Based on Ultrasound Findings in Pregnancy

• If intrauterine pregnancy confirmed: Conservative management with activity modification and reassurance is appropriate for mild, occasional pain. 7
• If ultrasound indeterminate: Serial beta-hCG monitoring and follow-up ultrasound in 2-7 days are necessary. 7, 4
• If ectopic pregnancy suspected or confirmed: Immediate obstetric/gynecologic consultation for potential surgical or medical management. 6, 7

Return Precautions for Patients

Counsel patients to return immediately for severe pain, vaginal bleeding, dizziness, syncope, or fever, as these may indicate progression to life-threatening conditions like ruptured ectopic pregnancy or sepsis. 7, 3