What is the initial workup for a patient presenting with an abdominal mass?

Initial Workup for Abdominal Mass

The initial workup for a patient presenting with an abdominal mass should begin with ultrasound as the first-line imaging modality, followed by CT or MRI based on the suspected diagnosis and location of the mass. 1

Initial Evaluation

History and Physical Examination Focus Points

• Location, duration, and progression of the mass 1
• Associated symptoms (jaundice, weight loss, abdominal pain, nausea, vomiting, fever) 1
• Risk factors for specific conditions (age, gender, family history) 1

Laboratory Studies

• Complete blood count (CBC) to assess for anemia or other hematologic abnormalities 2
• Comprehensive metabolic panel including liver and renal function tests 2, 3
• Tumor markers based on suspected origin:
  • CA-125 for suspected gynecologic origin 2, 4
  • Alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG) for patients younger than 35 years 2
  • Carcinoembryonic antigen (CEA) for suspected mucinous histology 2, 4
  • Lactate dehydrogenase (LDH) for certain ovarian malignancies, particularly germ cell tumors 2

Imaging Algorithm

Step 1: Ultrasound

• First-line imaging modality for all abdominal masses 1
• Helps determine if the mass is solid or cystic 1, 3
• Can assess vascularity and relationship to surrounding structures 3
• For suspected pelvic/adnexal masses, use transvaginal and transabdominal approaches 1
• For suspected abdominal aortic aneurysm, use duplex Doppler ultrasound 1

Step 2: Cross-Sectional Imaging

• For suspected malignancy or indeterminate ultrasound findings:

  • CT abdomen and pelvis with IV contrast is the preferred modality 1, 3
  • Provides detailed characterization of the mass, relationship to nearby structures, and assessment for metastasis 1

• For suspected adnexal/pelvic mass:

  • MRI pelvis without and with IV contrast if ultrasound is indeterminate 1
  • Superior for characterizing complex adnexal masses 1

• For suspected abdominal aortic aneurysm:

  • CT angiography (CTA) for definitive diagnosis and pre-intervention planning 1
  • MR angiography (MRA) if iodinated contrast is contraindicated 1

Step 3: Additional Imaging Based on Suspected Diagnosis

• For suspected cholangiocarcinoma: MRCP (Magnetic Resonance Cholangiopancreatography) 1
• For suspected bladder-related masses: CT urogram or cystoscopy 3
• For suspected soft tissue sarcoma: MRI with contrast 3

Diagnostic Approach by Location

Pelvic/Adnexal Mass

• Initial imaging: Transvaginal and transabdominal ultrasound with Doppler 1
• Laboratory: CA-125, AFP, hCG (age-dependent) 2, 4
• If indeterminate: MRI pelvis without and with IV contrast 1
• For suspected malignancy: CT abdomen and pelvis with IV contrast for staging 1, 4

Upper Abdominal Mass

• Initial imaging: Abdominal ultrasound 1, 3
• Laboratory: Liver function tests, tumor markers based on suspected origin 2, 3
• Follow-up imaging: CT abdomen with IV contrast 1, 3
• For suspected cholangiocarcinoma: MRCP 1

Pulsatile Abdominal Mass

• Initial imaging: Abdominal ultrasound with Doppler 1
• If confirmed or suspected AAA: CT angiography 1
• Alternative if CT contraindicated: MR angiography 1

Biopsy Considerations

• Image-guided core needle biopsy is preferred for suspicious solid masses 3
• Avoid fine-needle aspiration for suspected ovarian masses to prevent spillage of malignant cells 1
• Plan biopsy tract so it can be removed during definitive surgery if malignancy is confirmed 3

Common Pitfalls to Avoid

• Relying solely on clinical examination for diagnosis 3
• Performing biopsy before appropriate imaging, which may compromise treatment planning 3
• Using CA-125 alone for diagnosis of ovarian masses, as it can be elevated in many benign conditions 2
• Failing to consider age-appropriate tumor markers, particularly in younger patients 2
• Not performing a gastrointestinal evaluation in patients with mucinous histology 2, 4