A national population-based study of the incidence of adnexal torsion in the Republic of Korea

Abstract

Adnexal torsion is a condition wherein the ovary and/or the fallopian tube twist around their vascular pedicle, which may result in a venous/arterial occlusion [1]. This condition accounts for 2.7% of all gynecologic surgical emergencies [1]. However, most studies involve case series that report the experience at a single institution [2]. The aim of the present study was to evaluate the incidence of adnexal torsion in South Korea from 2009 to 2011. Data were analyzed using Korean Health Insurance Review and Assessment Service–National Inpatients Sample entries (HIRA-NIS; serial number: HIRA-NIS-2009-0066, 2010-0084, 2011-0063) covering the period January 1, 2009, to December 31, 2011. A detailed explanation of HIRA-NIS is provided in a previous study [3]. Cases with a simultaneous adnexal torsion diagnosis code (N835 according to the International Classification of Diseases-10 [4]) and an operation code were defined as an episode of adnexal torsion. Cases were counted by episode and not by patient. If a surgery for adnexal torion was performed more than 60 days after a previous surgery for adnexal torsion, it was assumed that the case involved an additional adnexal torsion episode. The MizMedi Hospital Institutional Review Board approved the study. R version 3.0.3 (R foundation, Vienna, Austria) was used for statistical analyses. Two-tailed independent t tests were used. The weighted χ2 text was used for proportions. During the study period, 1 843 451 women were included in the HIRA-NIS, among which 545 cases of adnexal torsion were identified. The incidence of adnexal torsion among women of all ages was 5.9 (95% confidence interval [CI], 5.4 − 6.4) per 100 000 women, and the incidence among women of reproductive age (15 − 45 years) was 9.9 (95% CI, 9.0 − 10.9) per 100 000 women (Table 1). The average age of occurrence of adnexal torsion was 33.79 (95% CI, 32.67 − 34.92) years. Age based on five-year intervals was associated with adnexal torsion in the weighted χ2 test (odds ratio 0.940; 95% CI, 0.927 − 0.953; P < 0.01) (Fig. 1). Incidence of adnexal torsion by age based on five-year intervals from 2009 to 2011 in Korea. Previous studies have reported on experience with adnexal torsion at a single institution and not its incidence [1]. According to a previous study, adnexal torsion frequently occurs in women of childbearing age compared with premenarchal or postmenopausal women [5]. These results were consistent with the results of the present study (Fig. 1). Although the present study has limitations attributed to diagnosis coding errors, it provides valuable information regarding the use of HIRA-NIS, which includes a large population that is useful for studying the low incidence of adnexal torsion. The authors have no conflicts of interest.