Parotid area sign: A clinical test for the diagnosis of fluid overload in hysteroscopic surgery

Abstract

Study objective To describe the clinical test parotid area sign, which is used to assess fluid absorption during resectoscopic surgery and to compare the test with volumetric fluid balance method with respect to its ability to detect fluid overload. Design Historical cohort study (Canadian Task Force classification II-1). Setting Tertiary endoscopy center. Patients Eighty-six women who underwent resectoscopic surgery between 1999 and 2004 at our center. Intervention The volumetric fluid balance method was used to evaluate glycine absorption (glycine deficit) during the surgery. A flexometallic ruler was placed on the left cheek of the patient between 2 fixed points: the midpoint of the philtrum and a point on the mastoid prominence, and this distance (philtrum-mastoid prominence distance) was measured at the beginning of every 3 minutes during, and at the end of the procedure. Measurements and main results Eighty-six patients were divided into 2 groups: Group A, which included patients with absorption less than 1000 mL as measured by the volumetric method; and Group B, which included patients with absorption of 1000 mL or more. The results of the parotid area sign test in the 2 groups were compared. The 2 groups were comparable with respect to the age, weight, preoperative measured philtrum-mastoid prominence distance, and hospital stay. The median (and average absolute deviation) operating time in group A (15 minutes [and 6.79]; range 8–60 minutes; 95% CI of the median, 15–20 minutes) was significantly lower than the median (and average absolute deviation) operating time in group B (25 minutes [and 8.96]; range 9–60 minutes; 95% CI of the median, 20–25 minutes; p <.001). The mean postoperative philtrum-mastoid prominence distance measured in patients of group A (14.23 ± 0.396 cm [range 14–16 cm, 95% CI 14.10–14.36 cm]) was significantly lower than that in group B [14.76 ± 0.622 cm (range 14–17 cm, 95% CI 14.58–15.12 cm]; p <.001). By paired t test, the change in the philtrum-mastoid prominence distance after surgery as compared with the value before surgery in each patient was found to be insignificant in group A (p =.86). However, it was found to be significant in group B (p <.001). The increase in the measured philtrum-mastoid prominence distance (i.e., postoperative measurement minus the preoperative measurement) in each patient after surgery was significantly more in group B (mean ± SD, 0.54 ± 0.362 cm [range 0–2 cm, 95% CI 0.43–0.65 cm]) than that in group A (mean ± SD, 0.03 ± 0.091 cm [range 0–0.4 cm, 95% CI 0.008–0.06 cm]; p <.001). The correlation coefficient for the increase in the philtrum-mastoid prominence distance as the glycine deficit increased in the 2 groups considered together was significant (r = 0.937, p <.01). The partial regression coefficient b value for the effect of duration of surgery while controlling for the effect of fluid deficit was 0.008 (p <.001), and the b value for the effect of fluid deficit while controlling for the effect of duration of surgery was 0.437 (p <.001). The regression coefficient r value (0.727) for the goodness of the fit of the regression line to the data sets was also significant (p <.001). The sensitivity of the test with respect to the volumetric fluid balance is 97.8% (95% CI, 87.28%–99.88%) and specificity is 92.3% (95% CI, 78.03%–97.99%). The negative predictive value is 97.30% (95% CI, 84.19%–99.85%) and positive predictive value is 93.87 (95% CI, 82.13%–98.40%). The conventional positive likelihood ratio for the test is 12.72 (95% CI 4.28–37.77). The conventional negative likelihood ratio is 0.023 (95% CI 0.003–0.16). Conclusion The parotid area sign is a simple, effective, and easy-to-perform test (in real time continuously) that requires minimal equipment or training. It supplements the volumetric fluid balance method in the detection of fluid overload (1.5% glycine) during resectoscopic surgery. It may also enable us to detect fluid overload when volumetric fluid balance method fails to detect extraneous losses caused by spillage.