What is the next step for investigating pelvic and groin pain?

Next Steps for Investigating Pelvic and Groin Pain

For patients with pelvic and groin pain, a pelvic ultrasound (transvaginal and transabdominal) should be the initial imaging study of choice, followed by MRI pelvis if the ultrasound is inconclusive or nondiagnostic.

Initial Imaging Approach

Pelvic Ultrasound (First-Line)

• Combined transabdominal and transvaginal ultrasound is the initial imaging study of choice for evaluating pelvic and groin pain 1
• Ultrasound can provide detailed anatomic information about:
  • Uterine size and endometrial canal distension
  • Fallopian tube dilation
  • Ovaries and adnexal masses
  • Pelvic fluid collections 1
• Doppler evaluation should be included as a standard component to assess:
  • Internal vascularity of pelvic structures
  • Distinguish fluid and cysts from solid tissue
  • Evaluate for vascular abnormalities such as pelvic venous disorders 1

When Ultrasound Is Inconclusive

MRI Pelvis (Second-Line)

• MRI is widely regarded as the problem-solving imaging examination of choice when ultrasound findings are nondiagnostic or inconclusive 1
• MRI provides superior soft tissue contrast and can identify:
  • Pelvic inflammatory disease
  • Adhesive disease (visualized as low-signal bands between structures)
  • Pelvic venous disorders
  • Peritoneal inclusion cysts 1
• When clinically indicated, gadolinium-based IV contrast is preferred 1

CT Abdomen and Pelvis (Alternative Second-Line)

• Consider CT when there is a broad differential diagnosis including both gynecologic and non-gynecologic etiologies 1
• CT with IV contrast may be useful for:
  • Poorly localized pain
  • Suspected masses involving both abdomen and pelvis
  • Assessment of abdominal vasculature and ascites 1
• CT has higher sensitivity than ultrasound (89% versus 70%) for urgent diagnoses in adults with abdominopelvic pain 1

Special Considerations Based on Suspected Etiology

For Deep Pelvic Pain

• If pelvic venous disorders are suspected:
  • Ultrasound with Doppler can document engorged periuterine and periovarian veins (>8mm), low-velocity flow, and altered flow with Valsalva maneuver 1
  • MRI/MR angiography has diagnostic performance comparable to conventional venography 1
  • Time-resolved postcontrast T1-weighted MRI can directly demonstrate ovarian vein reflux 1

For Chronic Inflammatory Disease

• Ultrasound may show pelvic fluid, hydrosalpinx, pyosalpinx, and peritoneal inclusions 1
• MRI with T2-weighted imaging can demonstrate edema, fluid collections, and distension of endometrial canal or fallopian tubes 1
• Postcontrast T1-weighted imaging and diffusion-weighted MRI are particularly important when infection is longstanding 1

For Suspected Musculoskeletal Causes

• Consider stress fractures, particularly in older or osteoporotic patients:
  • Radiographs have low sensitivity for sacral and pelvic insufficiency fractures 1
  • MRI can detect stress fractures within hours of injury 1
• For myofascial pain:
  • Ultrasound-guided trigger point injection of the iliopsoas, hip adductor, and lower abdominal muscles can be both diagnostic and therapeutic 2
  • The iliopsoas muscle is commonly affected in patients with chronic pelvic pain 2

For Neural Origin Pain

• Consider involvement of lateral femoral cutaneous, ilioinguinal, iliohypogastric, or genitofemoral nerves 3
• MRI can help identify nerve compression or irritation 3

For Discogenic Pain

• Lower-level lumbar disc herniation (L4-L5 or L5-S1) can sometimes present as groin pain 4
• MRI of the lumbar spine should be considered if other imaging is negative and back symptoms are present 4

Common Pitfalls and Caveats

• Relying solely on radiographs may miss important pathology, especially in the pelvis and sacrum due to overlying bowel gas, fecal material, and soft tissue 1
• Overreliance on nonspecific MRI findings can lead to misdiagnosis of stress fractures as more aggressive lesions 1
• When adhesive disease is suspected, real-time dynamic ultrasound or cine clips may document abnormal adherence or lack of mobility of structures, but adhesive disease remains notoriously difficult to confirm nonoperatively 1
• In patients with suspected bone pathology, biopsy should only be performed at a reference center by the surgeon who will carry out the definitive tumor resection or a radiologist member of the team 1