Laboratory Studies
No laboratory studies support the diagnosis of de Quervain tenosynovitis. The clinician may consider serologic testing for rheumatoid arthritis (ie, checking serum rheumatoid factor) if the patient has no history of either acute or repetitive trauma or other risk factors.
Imaging Studies
Usually, no imaging studies are required for diagnosing de Quervain tenosynovitis.
If a sufficient history of acute trauma exists, radiographs of the wrist are indicated to assess for fracture.
If the radiographs are negative but there is nonetheless a suggestion of fracture or osteonecrosis, further imaging studies can be pursued (eg, 3-phase bone scan). Triple-phase scintigraphy includes the following:
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Phase 1 - Flow phase (radionuclide angiography)
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Phase 2 - Blood pool phase (soft-tissue scintigraphy)
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Phase 3 - Late phase (skeletal bone scintigraphy)
After a fracture, increased flow and pooling may be seen in phases 1 and 2, but these findings are due only to local inflammation, which is not specific for fracture. Thus, increased uptake in phase 3 is the most important feature for diagnosis of a fracture, and this indicator may remain positive for months.
For fracture at the scaphoid, the 3-phase bone scan is believed to have a sensitivity of 100%, and many research studies use this test as the criterion standard for diagnosis of de Quervain tenosynovitis; in clinical practice, however, bone scanning is needed only if the plain radiographs are negative.
Increased thickness of the extensor pollicus brevis and abductor pollicus longus are the most reliable indications on a MRI scan of the wrist that de Quervain tenosynovitis is present. [25]
Despite the inroads made with imaging in de Quervain tenosynovitis, the accuracy of imaging in diagnosing the disease is unclear. For example, a literature review by McBain et al was unable to determine the value of imaging in de Quervain tenosynovitis, owing to variation between studies. The investigators reported that the most common imaging findings in the disorder were sheath effusion, retinaculum thickening, tendon thickening, increased vascularity, periostitis, periosteal apposition, radial styloid osteopenia, and calcified lesions in the tendon sheath. [26]
A study showed that the presence of an intracompartmental septum, which divides the first extensor compartment, can negatively affect the outcomes of corticosteroid injections. [27] The septum may impair through spread of the injectate throughout the entire first dorsal compartment. The study suggests that the presence of this septum may be a risk factor for de Quervain tenosynovitis, and that ultrasonography can nonsurgically detect this septum. Further research may be necessary to elucidate whether visualization of the septum using ultrasonography can then be used as a predictor as to the prognosis of an injection as a treatment or whether ultrasonographic guidance can overcome any outcome obstacles posed by the septum. For example, a study used ultrasonographic guidance to determine the presence or absence of a septum within the first dorsal compartment. If a septum was present, half of the injectate was administered, then the septum was pierced by the needle and the other half of the injectate was then administered on the other side of the septum. [28]
Procedures
No other diagnostic procedures are needed in most cases of de Quervain tenosynovitis.
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The first dorsal compartment of the wrist includes the tendon sheath that encloses the abductor pollicis longus and the extensor pollicis brevis tendons at the lateral border of the anatomic snuffbox.
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The Finkelstein test is performed by having the patient make a fist with the thumb inside the fingers. The clinician then applies ulnar deviation of the wrist to reproduce the presenting symptoms of dorsolateral wrist pain.
