1. Department of Obstetrics and Gynecology, Faculty of Medicine; University of Tsukuba; 1-1-1 Tennodai Tsukuba Ibaraki Japan
2. Department of Obstetrics and Gynecology; Tsukuba-Gakuen Hospital; 2573-1 Kamiyokoba Tsukuba Ibaraki Japan
3. Department of Urology, Faculty of Medicine; University of Tsukuba; 1-1-1 Tennodai Tsukuba Ibaraki Japan
4. Department of Urology; Tsukuba-Gakuen Hospital; 2573-1 Kamiyokoba Tsukuba Ibaraki Japan