Introduction. The systematization of surgical complications has long been a serious problem since different types of surgical procedures have specific complications, in addition to general consequences. Created in 1992 and improved in 2004, the Clavien-Dindo classification was successfully validated in surgical centers in different countries and recognized as an important tool for the qualitative assessment of surgical complications.
Aim. To improve reconstructive procedures by systematizing complications based on the Clavien−Dindo classification.
Materials and methods: The results of substitution ileocystoplasty in 95 patients with contracted bladder due to tuberculosis and other diseases are presented. In 50 (52.6%) cases, the length of the bowel segment was 30-35 cm (group 1, main), while in 45 patients (47.4%) a segment of 45-60 cm was chosen (group 2, control).
Results: Early complications of grade II developed in 11 (22.0%) patients in the group 1 and in 13 (28.9%) in group 2, while grade III in 5 (10.0%) and 6 (13.3%) cases, respectively. Complications of IIIb grade were seen among patients of the main group in 9 (18.0%) cases compared to 12 (26.7%) in the control group. Severe complications of IVa and IVb grades were documented with the same frequency in both groups, in one case each. Complications of V grade (death) were recorded only in the group 2. Late complications were registered in 63 out of 94 patients. In group 1, there were 26 complications (16 somatic and 10 surgical), while in group 2, a total of 37 complications (24 somatic and 13 surgical) were seen, which indicates a significant higher rate in the control group (p<0.05). In group 1, transurethral resection of urethral-enteric anastomosis and ureteral reimplantation were performed less frequently than in group 2, while transurethral resection of the prostate was done with the same frequency. At the same time, percutaneous nephrostomy was required more often in the group 1 (6% vs. 4.5% in the group 2).
After intestinal cystoplasty with a shortened fragment of the ileum, the voiding volume was significantly lower but corresponded to the physiological value (more than 150 ml). In this group, there was sufficient capacity of neobladder with a minimum amount of residual urine, effective emptying, satisfactory urinary continence, and low intraluminal pressure, which contributes to the protection of kidneys from reservoir-ureteral-pelvic reflux. The serum chloride level after surgery was 106.2±0.4 in the group 1 compared to 109.7±0.3 in the group 2, while base excess was -0.93±0.3 and -3.4±0.65, respectively
(p<0.05).
Conclusion: Early serious postoperative complications according to Clavien-Dindo were registered with approximately the same frequency in both groups, while late complications developed significantly more often in the group 2. The urodynamic parameters of a neobladder formed from ileum segment of 30-35 cm are satisfactory. In addition, a decrease in the length of the intestinal segment prevents the development of hyperchloremic metabolic acidosis.

Keywords: contracted bladder, ileocystoplasty, metabolic acidosis, tuberculosis