What is the most appropriate diagnostic test for a postpartum woman with wrist pain near the thumb, tenderness in the anatomic snuffbox, and restricted supination of the radial head?

Finkelstein Test is Most Appropriate for Diagnosing De Quervain's Tenosynovitis

The Finkelstein test is the most appropriate diagnostic test to confirm de Quervain's tenosynovitis in this postpartum woman with wrist pain near the thumb and tenderness in the anatomic snuffbox.

Clinical Presentation Analysis

The patient presents with classic symptoms of de Quervain's tenosynovitis:

• 32-year-old postpartum woman (high-risk demographic)
• Pain localized to the left wrist near the thumb
• Pain worsened by holding her baby (functional limitation)
• Tenderness in the anatomic snuffbox
• Restricted supination of the radial head

This clinical picture strongly suggests de Quervain's tenosynovitis, which is characterized by inflammation of the first dorsal compartment tendons (abductor pollicis longus and extensor pollicis brevis).

Diagnostic Test Selection

Finkelstein Test

The Finkelstein test is superior for diagnosing de Quervain's tenosynovitis with:

• Higher specificity than Eichhoff's test (often confused with Finkelstein's test)
• Significantly fewer false-positive results 1
• Less discomfort to patients during testing 1

The test involves the examiner grasping the patient's thumb and quickly ulnar deviating the wrist, which reproduces the characteristic pain of de Quervain's tenosynovitis.

Other Tests Considered

1. Allen Test: Used to assess the patency of radial and ulnar arteries, not appropriate for diagnosing tendon disorders 2

2. Eichhoff Test: Often mistakenly called Finkelstein's test, involves having the patient make a fist with the thumb inside and then ulnarly deviating the wrist. This test has lower specificity and more false positives 1

3. Hawkins-Kennedy Test: Used for diagnosing shoulder impingement, not appropriate for wrist disorders 2

4. Phalen Test: Used for diagnosing carpal tunnel syndrome, which would typically present with numbness and tingling (absent in this case) 3

5. Yergason Test: Used for diagnosing biceps tendon pathology, not appropriate for wrist disorders 2

Supporting Evidence

De Quervain's tenosynovitis is particularly common in:

• Women aged 30-50 years
• Postpartum women (4-6 weeks postpartum) 4
• Those performing repetitive hand/wrist movements 5

The American College of Radiology guidelines note that clinical examination is the cornerstone for detecting tenosynovitis 3, with imaging studies like MRI or ultrasound reserved for unclear cases or treatment planning 2.

Diagnostic Algorithm

1. Perform Finkelstein test (examiner-induced ulnar deviation of the wrist while stabilizing the thumb)
2. If positive: Confirms de Quervain's tenosynovitis
3. If equivocal: Consider the newer Radial Synergy Test which has superior specificity (99% vs 74% for Eichhoff's test) 6
4. If still unclear: Consider ultrasound imaging which can detect tenosynovitis with high specificity 3

Treatment Considerations

Once diagnosed with Finkelstein test, treatment options include:

• Thumb spica splinting
• NSAIDs for pain relief
• Corticosteroid injections (resolve symptoms in ~61% of cases after a single injection) 3
• Surgical release of the first dorsal compartment for refractory cases 7

Common Pitfalls

1. Confusing Finkelstein's test with Eichhoff's test (the latter produces similar pain by tendon stretching even in normal wrists)
2. Failing to recognize the high prevalence in postpartum women
3. Misdiagnosing as carpal tunnel syndrome (which typically presents with numbness and tingling)
4. Overlooking anatomical variations like accessory compartments which can affect treatment outcomes 5

By correctly using the Finkelstein test, you can accurately diagnose this patient's condition and initiate appropriate treatment to improve her symptoms and quality of life.