In a patient with left arm swelling 1.5 weeks after total shoulder arthroplasty, with intact circulation and no erythema, should I obtain a CT scan of the arm and order laboratory studies?

Imaging and Laboratory Workup for Post-TSA Arm Swelling

Start with plain radiographs and ultrasound as your first-line imaging; CT is not indicated at this stage, and routine laboratory studies are unnecessary unless specific clinical concerns arise.

Initial Imaging Approach

Begin with plain radiographs of the shoulder to assess hardware positioning, alignment, and rule out periprosthetic fracture 1. This should always be your starting point for any post-arthroplasty complication evaluation.

Add ultrasound examination to evaluate for:

• Joint effusion
• Bursal distention
• Soft-tissue fluid collections or abscesses
• Surrounding soft-tissue edema 1

Ultrasound is particularly useful here because your patient has intact circulation and no erythema, making soft-tissue pathology (seroma, hematoma, or early fluid collection) more likely than vascular compromise.

Why CT is NOT Indicated Now

CT of the arm is not appropriate at this stage 1. According to ACR Appropriateness Criteria, CT plays a role when:

• Radiographic findings need clarification
• Preoperative planning for revision is needed
• Hardware has been removed and you need to assess remaining bone stock 1

Your patient is only 1.5 weeks post-op with non-specific swelling—this doesn't meet criteria for advanced cross-sectional imaging yet.

Laboratory Studies: Skip Routine Testing

Routine postoperative laboratory studies are not justified in your scenario 2. A large retrospective study of 213 RSA patients found that 87.3% of routine postoperative labs did not influence patient management 2.

When Labs ARE Indicated:

Order labs selectively only if:

• Preoperative hemoglobin was <12 g/dL (predictor of transfusion need with OR 3.8) 3
• High Charlson Comorbidity Index with low BMI (predictor of electrolyte abnormalities) 2
• Clinical suspicion of infection (then order: CBC with differential, ESR, CRP, and consider joint aspiration) 1

Since your patient has no erythema and intact circulation, infection seems less likely, making routine labs even less useful.

Clinical Pitfalls to Avoid

Don't reflexively order advanced imaging for non-specific swelling. At 1.5 weeks post-op, some swelling is expected from surgical trauma. The absence of erythema and intact circulation are reassuring signs against infection or vascular compromise.

If symptoms progress or new concerning features develop, then escalate:

• Fever, erythema, or warmth → Consider infection workup (labs, joint aspiration under ultrasound or fluoroscopic guidance) 1
• Persistent or worsening pain → Consider CT with metal artifact reduction to evaluate hardware and bone 1
• Concern for DVT (though upper extremity DVT post-shoulder surgery is rare) → Venous duplex ultrasound

Recommended Algorithm

1. Obtain plain radiographs (AP, axillary, scapular Y views)
2. Perform or order ultrasound of the shoulder and arm
3. Observe clinically if imaging is reassuring
4. No routine labs unless specific risk factors present
5. Escalate to CT or labs only if clinical deterioration or specific findings emerge

The evidence strongly supports a conservative, stepwise approach rather than comprehensive testing for uncomplicated post-operative swelling 1, 2.