An abdominal mass refers to a discernible swelling or lump within the abdominal cavity, often incidentally discovered during a physical examination or imaging studies. These masses can result from a wide range of pathological processes, including organomegaly, neoplasms, cystic structures, abscesses, vascular abnormalities, or obstructive processes.

Timely recognition and characterization of an abdominal mass are essential, as certain etiologies may represent emergent, life-threatening conditions such as a rupturing abdominal aortic aneurysm (AAA).

Emergency considerations

Red Flag: Suspected Abdominal Aortic Aneurysm (AAA)A midline, pulsatile mass associated with acute, severe abdominal or back pain may indicate an expanding or ruptured AAA. Immediate interventions include:

• Stabilization:

  • Initiate high-flow oxygen

  • Establish two large-bore IV lines

  • Begin isotonic fluid resuscitation; prepare for transfusion

• Monitoring:

  • Continuous cardiac and hemodynamic monitoring

  • Monitor urinary output and neurologic status

• Imaging:

  • Bedside ultrasound or CT angiography (if stable)

• Pre-operative Measures:

  • NPO status

  • Urgent vascular surgery consultation

History & Physical Examination

A meticulous history and examination are critical for differential diagnosis.

History

• Pain: Onset, duration, character, localization, radiation, aggravating/alleviating factors

• Gastrointestinal: Changes in bowel habits, hematochezia/melena, nausea/vomiting, weight loss

• Urological: Dysuria, hematuria, urinary retention

• Gynecologic (females): Menstrual irregularities, pelvic pain, LMP, pregnancy status

• Systemic: Fever, fatigue, anorexia

Physical Examination Approach

Differential Diagnosis by Quadrant/Region

Investigations

Initial Laboratory Workup:

• CBC with differential (infection, malignancy)

• CMP (hepatic/renal function)

• Inflammatory markers (CRP, ESR)

• Urinalysis

• β-hCG (females of reproductive age)

• Tumor markers (e.g., CA-125, AFP, CEA) as appropriate

Imaging

• Ultrasound: First-line for most superficial, pelvic, or solid/cystic differentiation

• CT Abdomen/Pelvis with contrast: Gold standard for characterizing intra-abdominal masses

• MRI: Consider for better soft tissue definition, pelvic masses, or when radiation is contraindicated

Management principles

• Medical: Infections, inflammatory disorders, non-malignant cysts may respond to pharmacologic therapy

• Surgical: Indicated for neoplasms, abscesses requiring drainage, bowel obstruction, or AAA

• Oncologic: Multimodal management including surgery, chemotherapy, and/or radiation for malignancies

Patient communication & counseling

• Discuss diagnostic findings with clarity

• Offer appropriate referrals (e.g., surgery, oncology, gynecology)

• Emphasize follow-up and continuity of care

Special populations

Pediatric Considerations

• Palpation Tips:

  • Encourage relaxation with a pacifier or parental presence

  • Use distraction and warmth

• Common Pediatric Masses:

  • Neonates: Multicystic dysplastic kidney, hydronephrosis, ovarian cysts

  • Infants/Children: Wilms tumor, neuroblastoma, intussusception, mesenteric cysts, pyloric stenosis

Geriatric Considerations

• Thin patients may reveal normal aortic pulsation; differentiate from pathologic AAA using bedside ultrasound

• High index of suspicion for malignancy and vascular pathology due to age-associated risk

Clinical pearls

• Always exclude AAA in patients >50 with a new abdominal mass, especially if pulsatile

• Use imaging to characterize — don’t rely solely on clinical exam

• A non-tender, firm, fixed mass is more concerning for malignancy

• Consider iatrogenic and iatropathic causes (e.g., foreign body granuloma, surgical mesh hernia)

References

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