Radio frequency identification and surgical sponge detection

AORN Journal,  March, 2007  by George Allen

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Archives of Surgery

July 2006

Despite policies and procedures requiring perioperative personnel to count instruments and sponges before the surgical incision is closed, personnel continue to inadvertently leave sponges inside patients. Although retained sponges sometimes can remain undiscovered for decades without causing adverse effects, they also can lead to serious complications such as sepsis, internal obstruction, fistula formation, and death. Consequently, it is believed that a better system to prevent the retention of sponges before the patient leaves the OR would increase patient safety.

Continuing cost reduction and improved performance in radio frequency identification (RFID) technology, which is commonly used to prevent theft in retail stores, has now made it economically feasible to routinely attach RFID tags to surgical supplies. The RFID tags are tiny microchips that act as transponders, which respond to radio signals sent by transceivers or RFID scanners. A handheld, battery-powered wand scanning device measuring 10 inches x 10 inches x 1.5 inches has been developed to detect commonly used gauze sponges that have been tagged with RFID chips. The objective of this prospective, blinded study was to determine the success rate of the wand device in correctly detecting RFID-tagged surgical sponges placed in the surgical wound. (2)

A successful detection was defined as detection of an RFID sponge within one minute of beginning the scan. A convenience sample of eight patients undergoing a variety of elective abdominal and pelvic surgical procedures under general anesthesia at Stanford Medical Center, Stanford, Calif, was used for the study. An RFID tag measuring 20 mm in diameter and 2 mm in width was sewn into each sponge (ie, a 4-ply, adult laparotomy tape measuring 18 inches x 18 inches) and sponges were sterilized using the ethylene oxide technique.

At the end of the procedure and before the incision was closed, a randomly selected resident or attending surgeon placed an RFID surgical sponge in a randomly selected quadrant of the abdomen while the second surgeon looked away so as to be blinded to the sponge placement. The edges of the wound were then pulled together so that the inside of the cavity was not exposed during the detection phase of the study. The second surgeon used the handheld scanning device, which was enclosed in a sterile, plastic, disposable sheath, to scan the surgical area using the following standardized sequence: right upper quadrant, right lower quadrant, left lower quadrant, left upper quadrant, and then midline. The time from when the wand device was given to the surgeon until a sponge was detected was recorded.

Three additional random placements of sponges were performed for each patient, for a total of four placements in each patient. In one of the four placements for each patient, an untagged sponge (ie, the control) was used to determine the rate of false positives (ie, when the device indicated the presence of an RFID sponge when there was none). Researchers also recorded the rate of false negatives (ie, when the device did not indicate the presence of an RFID sponge when one had been placed). In five of the patients, two RFID sponges were placed simultaneously during one of the placements to determine if the wand device would detect a concurrent second RFID sponge.

After the scanning phase was completed, a one-page questionnaire was administered to the surgeon and nurse involved in the detections. The questions related to the wand's overall quality, ease of use, and its ability to contribute to efficiency and patient safety. Responses were based on a zero to 100 visual analog scale. Space was left at the end of the questionnaire for suggestions to improve the device and for general comments. Common statistical procedures were used to analyze the data.

Findings. Eight untagged sponges and 28 RFID-tagged sponges were placed in the eight patients. The RFID wand device detected all tagged sponges correctly, and there were no false negative or false positive results. On average, the RFID sponges were detected in less than three seconds. Both nurses and surgeons rated the RFID wand device high on ease of use and its ability to improve patient safety and lowest for its ability to increase efficiency. Concern was expressed, however, that human error would persist in the detection of RFID sponges unless the technology was designed to be fail-safe.

Clinical implications. The results of this study demonstrated 100% detection accuracy using RFID sponges and the RFID wand device, with a 0% false negative rate and a 0% false positive rate. Perioperative personnel must understand that this device currently does not provide a fail-safe process. If the scan is performed incorrectly (eg, the wand is too far away from the skin to detect the sponges or the wand does not cover the entire surface area of the surgical site), retained sponges could be missed. Retained sponges also can be missed if the scan is performed too early--for example, if additional sponges are placed in the wound to help with the closure after the final RFID scan has been performed. Perioperative nurses and managers should be prepared to participate in further analyses of this type of device to determine its cost-effectiveness and to help further research that may facilitate the design of a fail-safe device.