What is the appropriate workup and management for a patient presenting with an abdominal mass?

Workup and Management of Abdominal Mass

Begin with ultrasound as the first-line imaging modality for all abdominal masses, followed by CT with IV contrast for suspected malignancy or indeterminate findings, and proceed to tissue diagnosis via image-guided core needle biopsy for solid masses before definitive surgical management. 1

Initial Clinical Assessment

Physical Examination Priorities

• Immediately assess hemodynamic stability: Check vital signs (pulse, blood pressure, temperature) looking specifically for tachycardia, fever, or hypotension indicating perforation or sepsis 2
• Evaluate for peritoneal signs: Document guarding, rigidity, and rebound tenderness 2
• Characterize the mass: Determine location (quadrant), size (measure dimensions), consistency (solid vs cystic), mobility, and pulsatility (suggests vascular origin like AAA) 2
• Perform digital rectal examination: Essential for lower abdominal and pelvic masses 2
• Document associated findings: Look for weight loss, cachexia, jaundice, lymphadenopathy, skin changes, or abdominal distension 2

Imaging Algorithm by Location

Pelvic/Adnexal Masses

• Initial imaging: Transvaginal and transabdominal ultrasound with Doppler 1
• If ultrasound indeterminate: MRI pelvis without and with IV contrast (superior for characterizing complex adnexal masses) 1
• Laboratory workup: CA-125, AFP, beta-hCG (in women <35 years), inhibin, CEA (if mucinous histology suspected) 3, 4
• Special consideration: For mucinous histology, perform gastrointestinal tract evaluation to rule out metastatic disease from GI primary 3, 4

Upper Abdominal Masses

• Initial imaging: Abdominal ultrasound 1
• Follow-up imaging: CT abdomen/pelvis with IV contrast for suspected malignancy or indeterminate ultrasound 1
• Laboratory tests: Liver function tests, tumor markers based on suspected origin, AFP for hepatocellular carcinoma 3, 1

Pulsatile Abdominal Masses

• Initial imaging: Abdominal ultrasound with Doppler 1
• If AAA confirmed or suspected: CT angiography 1
• Pitfall to avoid: Normal aortic pulsation can be prominent in thin patients—don't assume all pulsatile masses are aneurysms 2

Retroperitoneal/Mediastinal Masses

• Imaging: CT chest, abdomen, and pelvis 3
• Laboratory tests: Beta-hCG and AFP (especially in men <65 years to rule out germ cell tumor) 3
• Additional testing: Testicular ultrasound if beta-hCG or AFP elevated in men 3

Tissue Diagnosis Strategy

Biopsy Approach

• For solid masses >2 cm: Image-guided core needle biopsy is preferred (via endoscopic ultrasound or CT/ultrasound-guided percutaneous approach) 3
• Plan biopsy tract: Ensure it can be removed during definitive surgery if malignancy confirmed 1
• Avoid FNA for suspected ovarian masses: Prevents spillage of malignant cells into peritoneal cavity 3, 1
• Small nodules <2 cm: Consider endoscopic ultrasound assessment with follow-up, reserving excision for growing or symptomatic lesions 3

When to Proceed Directly to Surgery

• Laparoscopic/laparotomic excision indicated for:
  • Abdominal nodules not amenable to endoscopic assessment 3
  • Rectal nodules (regardless of size, due to higher progression risk) 3
  • Obvious metastatic disease (biopsy metastatic focus, avoid laparotomy for diagnosis) 3

Essential Laboratory Workup

Standard Tests for All Patients

• Complete blood count (assess for anemia) 4
• Comprehensive metabolic panel (liver and renal function) 4
• Fecal occult blood testing 3

Age and Gender-Specific Markers

• Men >40 years: PSA (except if metastases limited to liver or brain) 3
• Women <35 years with pelvic mass: AFP and beta-hCG to assess for germ cell tumors and rule out pregnancy 3, 4
• All pelvic masses in women: CA-125, inhibin, CEA 4
• Suspected sex cord-stromal tumors: Inhibin levels 4

Additional Testing Based on Presentation

• Bone involvement: Bone scan (if PET/CT not performed) and radiographic studies 3
• Retroperitoneal mass: Urine cytology, followed by cystoscopy if suspicious 3
• Inguinal lymph node involvement: Proctoscopy, perineal and lower-extremity examination 3

Additional Imaging Considerations

• Chest imaging: Recommended before surgical staging to evaluate for metastases 3
• Upper/lower endoscopy: Indicated if symptoms suggest gastrointestinal or visceral involvement 3
• PET/CT scan: Consider for unexplained lymphadenopathy, visceral masses, or bone lesions 3

Critical Pitfalls to Avoid

• Do not rely solely on CA-125: Elevated in many benign conditions and may be normal in early-stage ovarian cancer 4
• Do not skip plain abdominal radiography in acute presentations: Can identify bowel obstruction, perforation, or masses 2
• Do not assume imaging findings are malignant without tissue diagnosis: Opportunistic infections and benign processes can mimic malignancy, especially in immunocompromised patients 3
• Do not fail to consider age-appropriate tumor markers: Particularly critical in younger patients to avoid missed germ cell tumors 4