Follow-up after urinary diversion

With modern forms of urinary diversion being widely employed during recent years, the awareness of possible complications and appropriate follow-up st rategies gains rising importance and current follow-up strategies are revie wed herewith. Follow-up investigations after urinary diversion have to addr ess possible surgical complications, metabolic changes as well as the risk of secondary malignancies in the incorporated bowel segments. The most impo rtant and possible deleterious surgical complication is upper tract dilatio n and obstruction following ureteroenteric anastomotic stenosis and occurs in 2-30% depending on the surgical technique and evaluated series. The most appropriate follow-up study to detect upper tract dilation is ultrasonogra phy while the associated obstructional component can best be estimated by f unctional renographic studies (MAG(3) renal scan). The significance of refl ux associated with urinary diversion remains controversial although experim ental studies and clinical observations suggest a risk of renal functional deterioration associated with reflux which is certainly true in ureterosigm oidostomy following pyelonephritic changes. Possible metabolic changes incl ude hyperchloremic metabolic acidosis and problems related to malabsorption due to bowel resection and incorporation of bowel segments into the urinar y tract. The incidence of hyperchloremic acidosis is related to the form of urinary diversion, being higher in continent forms than in incontinent div ersions, while hyperchloremic metabolic acidosis is most frequently encount ered in ureterosigmoidostomy. While acute complications of metabolic acidos is may encompass hyperventilation as well as severe changes of serum electr olytes and acid base balance leading to cardiac arrhythmias necessitating i mmediate hospital treatment with intravenous alkalinizing, chronic acidosis may lead to osteopenia through hypocalcemia and stimulation of osteoclasti c activity. Metabolic acidosis can be best detected by regular blood gas an alysis. To prevent these complications prophylactic administration of alkal inizing agents (e.g. potassium citrate) should be readily performed. Malabs orption of bile acid strongly correlates with the length of ileum resected and can induce both chologenic diarrhea and malabsorption of liposoluble vi tamins (A, D, E, K). Vitamin B-12 is exclusively absorbed in the distal ile um, se rum levels therefore may be reduced following resection of distal il eum. This will not occur during the first 3-5 years following diversion bec ause B-12 deposits usually will last for this period. Later, however, serum levels of vitamin B-12 should be checked annually while others favor routi ne substitution of this vitamin. The incidence of cancer occurring at the u reterointestinal anastomosis seems to be highest in patients with ureterosi gmoidostomy varying between 2 and 29% with polypoid benign lesions being mo re frequent. The most common type of tumor is adenocarcinoma which has also been reported in colonic and ileal conduits as well as augmentation cystop lasty using either colon or ileum. Since the time interval between surgery and cancer occurrence is longer than 10 years, the newer forms of continent diversion theoretically also inherit the risk of tumor formation, which, h owever, has yet to be established because these diversions are only in wide use since 10 years. Currently, annual endoscopic controls are recommended in those patients with diversions where feces and urine are in contact with urothelium starting 5 years after surgery. Although formal guidelines for follow-up after urinary diversion have not y et been established by the working group on oncology of the German urologic al association, this paper suggests a follow-up strategy addressing surgica l complications, metabolic changes and the risk of secondary malignancies. Copyright (C) 1999 S. Karger AG.,Basel.