Pelvic lymph node dissection (PLND) is the most accurate staging tool to determine lymph node involvement in prostate and bladder cancer. The main complication of PLND is development of a lymphocele, which can cause symptoms including lower abdominal pain, leg or penile/scrotal edema, bladder outlet obstruction, deep venous thrombosis or infection/sepsis. The incidence of radiographic (asymptomatic) and symptomatic lymphoceles following PLND varies between 12,6-63% and 1,6-33% respectively. Medicated sponges such as Tachosil® are indicated in surgery for improvement of haemostasis and to promote tissue sealing. They could reduce lymphocele development by increased tissue sealing, due to a mechanical effect of the sponge itself and a lymphostatic effect of the included thrombin and fibrinogen. Our goal is to prospectively assess the lymphostatic effect of Tachosil(r) in patients undergoing transperitoneal PLND with or without radical prostatectomy or PLND with bladder cancer surgery.