Background
The aim was to investigate the presence of feeding vessels in or in close proximity to extensor and flexor tendon sheaths at the wrists level and in finger flexor tendon sheaths in healthy controls, using 3D ultrasound (US), which may cause pitfalls, in order to ensure correct interpretation of Doppler signals when diagnosing tenosynovitis.

Method
Forty healthy participants (20 women and 20 men age 23-67 years) without prior history of arthritis, tendon diseases or present pain in their hands were included. Twenty participants had 3D Doppler US of the second and third finger and twenty of the right wrist. US was carried out using a GE Logiq E9 unit with a 3D US probe. The colour Doppler settings were to published recommendation.

Results
The feeding vessels in or in close proximity to the tendon sheaths were found in the flexor and extensor tendons sheaths at least once in each participant. No significant difference in feeding vessels was seen between the radial and carpal level in the wrist (p = 0.06) or between the second and third flexor tendon sheath (p = 0.84).

Conclusion
Doppler findings in or in close proximity to the tendon sheaths were common in wrists and fingers in healthy participants. These feeding vessels can be a source of error, not only due to their presence but also because they may be interpreted as being inside the tendon sheath due to blooming and reverberations artefacts. These vessels should be taken into consideration when diagnosing Doppler tenosynovitis.