Sensitivity of Radiofrequency Devices for Detection of Retained Surgical Sponges in Morbidly Obese Subjects

Friday, 3 August 2012: 8:50 AM

Victoria M. Steelman, PhD, RN, CNOR, FAAN
College of Nursing, The University of Iowa, Iowa City, IA

Learning Objective 1: Compare the sensitivity of detection of surgical sponges, using a radiofrequency mattress, in subjects who are versus are not morbidly obese.

Learning Objective 2: Compare the sensitivity of detection of surgical sponges in morbidly obese subjects, using a radiofrequency mattress versus a wand.

Purpose:  The purpose of this study is to evaluate the sensitivity and specificity of the detection of surgical sponges through the torso of non-morbidly obese and morbidly obese subjects using a radiofrequency mattress.

Methods: A prospective, crossover, and observer blinded study design was used. Subjects served as their own controls. With the subject supine, 4 surgical sponges were sequentially placed on top of the subject’s torso in locations approximating abdominal quadrants. In a subset of 118 subjects, the effectiveness of the RF mattress was compared to that of the RF wand.

 Results: 203 subjects were enrolled in the study, 61.1 % (n=129) of whom were morbidly obese (BMI =/>40). 812 readings were taken with the RF mattress. In subjects with a body mass index (BMI) < 40, sensitivity and specificity of the mattress were 100%. In subjects with a BMI =/>40, the sensitivity of the mattress was 96.9% and specificity was 100%.  The mattress failed to detect 12 surgical sponges in 10 subjects with BMI ranging from 50.2 to 78.8. The results of the mattress were compared to those of RF wand in 118 subjects, including 85 who were morbidly obese. Sensitivity and specificity of the wand were 100% for non-morbidly obese and morbidly obese subjects.

 Conclusion: The sensitivity and specificity of RF mattress and wand technology are much higher than published reports of surgical counts or intraoperative radiographs for retained surgical items. The sensitivity of the RF wand is superior to the RF mattress for detection of sponges in morbidly obese subjects. Findings were consistent with a previous study finding the sensitivity of the wand to be 100%.