Urologic and metabolic consequences of continent urostomy (Kock reservoir) in children and adolescents

Abstract

During the last decades, urinary diversion using an intestinal segment has been commonly used in children and adolescents. Kock pouch is a feasible alternative for the children in need of a continent diversion where other alternatives such as Mitrofanoff are excluded for various reasons. The present study focused on the evaluation of the urologic and metabolic consequences after continent urinary diversion (Kock reservoir) and the assessment of the quality of life after surgery in children and adolescents. Twenty patients with congenital urinary incontinence were operated and followed for 3-12 years. The reservoir and upper urinary tract were studied through enterocystometry, enterocystoscopy, enterocystography, intravenous urography and clinical history. Acid-base status, serum electrolytes, vitamin B12, folate, methylmalonic acid (MMA) and homocystine were measured. Renal function was assessed by Cr51 EDTA clearance and serum creatinine and the split renal function by (99m) Tc-MAG 3 renoscintigraphy. Patients answered a questionnaire that covered medical, physical, social and body image aspects. The follow-up was divided into different periods: early -EFU (3 months - 2 or 5 years), and late -LFU (2-10 or 5-12 years after surgery).A low reservoir pressure was accompanied by high capacity and compliance. Nipple malfunction (angled nipple, prolapsed or stenosed stoma) occurred in 35% and stones in 40% of patients. Reservoir perforation was observed in 2 patients. An excellent continence was reported in 90% and a good one in the rest of patients. Angled efferent nipple seen on enterocystoscopy or enterocystography coincided with nipple malfunction, reservoir mal-position or infrequent emptying (= 4 times/day). Ureteral dilatation was detected in 84% of patients 3 months after surgery. The dilatation was improved in 56% and unchanged in 25% of patients after one year, and then it continued to improve at the LFU. New focal renal scars were radiologically detected in 2 patients. Three patients had metabolic acidosis and 8 had hyperchloremia. Serum creatinine level was increased in 82% of patients with infrequent emptying at the LFU (P<0.05). GFR was below normal in 4 patients preoperatively, in 6 at the EFU and in 8 at the LFU. Two patients developed low B12 values and 2 had elevated MMA with normal B12 values. Blood folate was low in 5 patients at the EFU and in different 5 at the LFU. There was no correlation between the resected ileal segment length and B12 value.Physical activities were not hampered by the operation in any patient. Instead, some activities as full day outside home and friend at home over night were increased in some patients. More than half of patients had excellent positive self-esteem and body image and the rest had good one. However, some patients were concerned about how they looked and felt that life was unfair to them.Conclusion: Kock reservoir remains a viable alternative to other forms of continent urinary diversion. The stability of the reservoir volume and low internal pressures was achieved early after operation depending on the frequency of the reservoir emptying. Efferent nipple malfunction is common during the first 2 years after surgery. The Kock pouch provided a satisfactory continence to all patients, although a revisional operation was necessary in some patients to get a permanent continence. Urinary tract dilatation is a frequent finding postoperatively, but it subsides in most cases 3-12 months after surgery. Long-term afferent nipple dysfunction may be the result of angulation, reservoir stones, mal-position and/or over-distension. Permanent renal damage may be due to pyelonephritis, stones, infrequent reservoir emptying, urinary obstruction, or metabolic acidosis. A strict regime of reservoir evacuation to decrease the possibility of metabolic alterations and of renal function deterioration is strongly advisable in these patients. Vitamin B12 and folate values should be monitored regularly. B12 deficiency is neither correlated with the time elapsed since surgery, nor with the resected ileal length. Serum MMA and homocystine may offer increased detection of occult B12 deficiency. The patients were physically active and declared a positive perspective regarding self-esteem and body image. The medical problems related to the operation did not have any negative influence on the self-esteem or body image. The choice of the operation can only be determined on the basis of an attentive dialogue between surgeon, child and parents.