The design of the trial will be as a single-center, prospective, open-label, randomized trial comparing the infusion of Activase versus saline for treatment of loculated abdominopelvic abscesses requiring percutaneous drainage. Patients with loculated abdominopelvic abscesses who are referred for percutaneous drainage will be eligible for this study. Patients will undergo standard placement of a 10-12 french percutaneous drain into their abscess cavity under computed tomography guidance. If the entire contents of the abscess cavity cannot be aspirated at the time of initial catheter placement, the abscess will be assumed to be loculated. The patient will then be randomized to have their abscess catheter irrigated twice a day with a volume of fluid approximately equal to the one-half the residual volume of the abscess. In the control group, the normal saline will be fluid instilled into the abscess cavity. The study group will receive Activase reconstituted in sterile water and then diluted to the appropriate volume with normal saline.