We are developing a computerized system for automated segmentation of ureters in CT urography (CTU), referred to as COmbined Model-guided Path-finding Analysis and Segmentation System (COMPASS). Ureter segmentation is a critical component for computer-aided diagnosis of ureter cancer. A challenge for ureter segmentation is the presence of regions not well opacified with intravenous (IV) contrast. COMPASS consists of three stages: (1) adaptive thresholding and region growing, (2) path-finding and propagation, and (3) edge profile extraction and feature analysis. One hundred fourteen ureters in 74 CTU scans with IV contrast were collected from 74 patient files. On average, the ureters spanned 283 CT slices (range: 116 to 399, median: 301). More than half of the ureters contained malignant or benign lesions and some had ureter wall thickening due to malignancy. A starting point for each of the 114 ureters was selected manually to initialize the tracking by COMPASS. Path-finding and segmentation were guided by the anatomical knowledge of ureters in CTU. The segmentation performance was quantitatively assessed by estimating the percentage of the length that was successfully tracked and segmented for each ureter. Of the 114 ureters, 110 (96%) were segmented completely (100%), 111 (97%) were segmented through at least 70% of its length, and 113 (99%) were segmented at least 50%. In comparison, using our previous method, 79 (69%) ureters were segmented completely (100%), 92 (81%) were segmented through at least 70% of its length, and 98 (86%) were segmented at least 50%. COMPASS improved significantly the ureter tracking, including regions across ureter lesions, wall thickening and the narrowing of the lumen.