Thumbs up: Needle marker technique for preoperative localisation of radiolucent foreign bodies with ultrasonography()

BACKGROUND: A 26-year-old man presented with pain and swelling after pricking his right thumb pulp with a thorn, gardening three-weeks previously. TECHNIQUE: After a thumb digital ring block with local anesthetic, a linear array ultrasound (US) transducer (frequency XX) identified a foreign body (FB) in both longitudinal and transverse planes. This was a hyperechoic FB, 5mm in length with surrounding hypoechoic shadow, denoting granulation tissue and fluid collection. Two 20G needles were passed orthogonally, in-line with the US transducer, from the fingertip and ulnar aspect. The needle tips were placed touching, just deep to the FB, preventing displacement. A longitudinal incision was made over the intersection, revealing the FB. DISCUSSION: Here, we describe peri-operative localization of radiolucent FBs with ultrasonography needle placement in superficial or deep planes as an adjunct to necessary surgical exploration. This method has a small learning curve, reduces the required incision and helps prevent pushing the FB deeper during dissection.