Another use of ultrasound by the anesthetist
Abstract
The use of ultrasound by anesthetists in an operating theatre environment generally relates to regional nerve blocks or central venous access. Other potential uses include identification of epidural space, draining pleural effusion, identification of vascular anatomy before tracheostomy etc.1. We present an instance where the use of ultrasound prevented cancellation of elective minor surgery. There have been no similar reports in the literature before.
A young woman weighing 95 kg was listed for elective surgery to remove a contraceptive implant (Implanon®) from her left arm under local anesthetic. Her general practitioner had been unable to remove the implant due to his inability to palpate the device. In the outpatient gynecology clinic the implant had been located in the subcutaneous tissue of the medial aspect of the left arm with the help of ultrasound, but the exact location was not marked. On the day of the surgery in the operating room, the gynecologist could not ‘feel’ the implant at the location mentioned by the previous ultrasound report. She was reluctant to explore the area and considered referring to orthopedic or plastic surgeon for guidance. Unluckily, there were no general, orthopaedic or plastic surgery cases scheduled for that day in that complex. The ‘on call’ surgeons were busy operating in another complex. The gynecologist then suggested that the surgery be postponed and the patient referred to the surgeon for rescheduling at a later day.
At this point, the ultrasound machine in the operating room, BK Medical Flexfocus 400 Anesthesia® (BK Medical, Denmark) with an 8870 probe at a frequency of 15MHz, was successfully used by the anesthesia team to locate the implant as a linear shadow about 2 cm below the skin buried in the subcutaneous fat. The location was marked and the surgeon then removed the implant under local anesthetic without any complications. Timely use of the ultrasound prevented cancellation of the procedure.
Contraceptive implants occasionally migrate into deeper tissues2 and become difficult to palpate. Although the use of ultrasound to locate these implants has been described3, there have been no reports in an operating room by the anesthetists. A recent review concluded that the use of ultrasound as a primary diagnostic device had a sensitivity of 85% and a specificity of 95.7%4. In selected cases, ultrasound may be a useful adjunct to visualise foreign bodies and implants in subcutaneous tissue.
