Check for surgical sponges using radiofrequency apparatus

By Sarah Guy, medwireNews Reporter

A radiofrequency (RF) mat or wand is able to detect the presence of surgical sponges with complete accuracy, indicating that the method is superior to either a manual sponge count or an intraoperative radiograph, report researchers.

Furthermore, the study findings indicate that the RF wand will detect sponges in patients who are supermorbidly obese - a known risk factor for retained items - with greater accuracy than the mat, remarks the team in the Archives of Surgery.

"Therefore, the use of the RF device technology can save significant time and additional operating room costs associated with resolving a count discrepancy," say Victoria Steelman and Mohammad Alasagheirin from The University of Iowa, USA.

The study included 203 patients and visitors to a bariatric clinic who were a mean 44 years of age, and who had BMIs ranging from 20.9 to 78.8 kg/m², where a BMI of at least 30.0 kg/m² indicated obesity and 90.1% of participants fitted this criterion.

Each participant lay on a mattress fitted with an RF mat, and had sponges fitted with an RF chip - like those used during surgical procedures to absorb liquids - randomly placed on their torso; the RF mat scanned the presence of the sponges.

The second phase of the study, involving 117 of the original participants, mirrored the first, except that the RF wand was used to scan participants' bodies for sponges.

Of the total 812 RF readings obtained using the mat, there were no false positives and only 12 false negatives - all in patients with morbid obesity - giving an overall sensitivity and specificity of 98.1% and 100.0%, respectively. For patients with morbid obesity (BMI >40.0 kg/m², 63.5%), the corresponding sensitivity and specificity was 96.9% and 100.0%.

By contrast, the RF wand gave a total of 355 true positive and 113 true negative readings, resulting in a sensitivity and specificity of 100.0% for all participants of the second phase of the study, including the 72.6% who fit the morbid obesity criterion.

This level of accuracy "far surpasses" that found in previous studies of manual surgical counts (77.2%) and intraoperative radiography (66.7%), note the researchers.

"The RF mat is narrower than the operating room bed, and the abdominal cavity of patients with morbid obesity can exceed the width of the mat," explain Steelman and Alasagheirin, adding that this "likely explains the false negatives that were found with the use of the RF mat."

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