Long-term Survival of Bladder Augmentation is Influenced by its Shape and Mucosal Lining

Bladder augmentation in the UK has been largely by enterocystoplasty or ureterocystoplasty (UC). Ileocystoplasty can be simple patch placement (SPP), or formation of an ileal cup (IC). Urothelium is the "right" mucosa, whereas intestinal mucosa exhibits absorption, mucus production, malignancy. On videourodynamics it can be shown that SPP fills with a poor conformation (irregular shape), while IC was good, and UC adequate. Our aim was to measure the long-term outcomes of augmentation, comparing UC ("right" mucosa and adequate conformation), to SPP ("wrong" mucosa and poor conformation) to IC ("wrong mucosa" and good conformation).

Single-centre retrospective review. Patients were identified from operative logs for the period 2005 to 2022. Registered as an audit (CARMS 31503). Data collected included: demographics, dates: operation, redo-surgery, imaging, stones (renal/bladder) and any intervention. Data were given as numbers (%), median (range) analysed by Fisher exact test where P < 0.05 was taken as significant.

There were 168 bladder augmentations: UC (n = 24), SPP (n = 72), and IC (n = 72). Follow-up was no different for IC 4.23 (0.05-11.50) vs SPP 4.43 (0.15-13) yrs, but was longer for UC at 6.2 (4.1-8.9) yrs. Age at augmentation was 6.7 (2.5-17.1) vs 8.1 (2-17) vs 11.6 (5.9-17) yrs respectively (UC vs IC vs SPP, P = 0.0001). Revision surgery was required in 3/24 (12.5 %) UC, 6/72 (8.3 %) SPP, and 0/72 (0 %) IC. IC had fewer redos than SPP, P = 0.028. Long-term survival was significantly better for IC (100 % at 10 years, vs UC 85 % at 10 years and SPP 96 % at 5 yrs and 75 % at 10 yrs, log-rank P < 0.05). Imaging follow-up was available in SPP (n = 56) IC (n = 62), UC (n = 24) with renal stones identified in 7/56 (%) SPP, 2/62 (%) IC, and 0 in UC. Bladder stones were present in SPP 5/56 (8.9 %) vs IC 2/62 (3.2 %), NS. Stone-free survival was 100 % at 10yrs in UC, 95 % in IC, and 62 % in SPP, P = 0.028. Combining bladder failure leading to reaugmentation and bladder stones requiring surgery, allows comparison between SPP and IC: In SPP bladder stones and augment failure occurred in 15.3 %, vs 2.8 % in IC. There is a 6.3-fold increase in bladder stones and augment redo with SPP [irregular filling bladder (poor conformation) and the "wrong" mucosa] vs IC (good confirmation, but "wrong" mucosa).

Augmentation survival is influenced by conformation and presence of the "right" mucosa. UC is only possible in 14 % of cases, and an IC is preferable to SPP when an enterocystoplasty is needed.