18 Ureter: How to Avoid Injuries in Various Hysterectomy Techniques Manoel Afonso Guimarães Gonçalves, Fernando Anschau, Daniela Martins Gonçalves and Chrystiane da Silva Marc Pontifical Catholic University of Rio Grande do Sul Brazil 1. Introduction Hysterectomy is one of the most common surgical procedures in the practice of gynecology. The various surgical techniques for hysterectomy, including those by the abdominal approach as well as those by the vaginal route, deserve special attention with regard to possible transoperative urological injuries. These complications raise questions about the anatomic knowledge for all gynecologists. The ureters are vulnerable to injuries during gynecological surgeries and even obstetric ones due to the anatomic proximity to the organs of the female reproductive system. 1 The general incidence of ureteral injuries is estimated to be 0.03% to 2.0% for abdominal hysterectomy, 0.02% to 0.5% for vaginal hysterectomy, and 0.2% to 6.0% for laparoscopy-assisted vaginal hysterectomy. 2, 3, 4, 5, 6 There are four critical points of potential ureteral injury during a hysterectomy. The first critical point is situated at the entrance of the ureter in the pelvic bone, when the ovarian vessels cross over it. The second critical point is identified next to the uterosacral ligament, where the ureter is situated lateral to this ligament. The third critical point is at the level of the uterine artery, where the ureter crosses below the uterine artery through the cardinal ligament at the level of the ischial spine. The fourth critical points occurs in the bladder, where the ureter turns medially, crossing the anterior portion of the vaginal dome and entering the bladder wall. 7 Certainly, the ability to recognize the anatomy, as well the ability of the surgeon in recognizing the points of greater risk of ureter injury, will help in lowering these percentages. 2. Anatomy The ureter is a tube that is part of the urinary tract and that connects the renal pelvis to the bladder. Its function is to transport the urine from the kidney to the bladder, which involves peristaltic or wave-like movements by contraction of its smooth muscle layer. The ureters have three layers, like other tubular organs: (i) the outermost layer consists of connective tissue, partially covered by the serosa in the regions where the ureter is in contact with the peritoneum; (ii) in the intermediate portion, there is a middle layer consisting of smooth muscle tissue of three types, circular, longitudinal and oblique; (iii) the inner layer is composed of mucosa – with transition epithelium - and submucosa – with connective tissue.