Factors affecting the fate of prolonged forgotten 'J' stents

Purpose: To compare the effects of age and presence or absence of renal imp airment at the time of 'J' stent insertion on the subsequent fate of prolon ged forgotten stents. Patients and methods: A patient was described as having a prolonged forgott en 'J' stent, if the patient's 'J' stent was removed more than 12 months af ter it had been inserted. We compared the effect of age at insertion and pr esence or absence of renal impairment on the complications encountered in s uch patients. We describe briefly the management of the complications. We d efined a patient as having moderate renal impairment if the patient has ser um creatinine > 200 < 500 mu mol/l and is not on dialysis. Results: We treated 17 patients with forgotten 'J' stents between 1994 and 2000. Fifteen were adults, mean age 25 (range 18-72) years, and 2 were chil dren 9 and 10 years respectively at the time the stents were inserted. The mean duration of stent retention was 24.30 (range 12-60) months. In 12 pati ents the stents were forgotten for between 12 and 18 months. In these, the stents had varying degrees of calcification but were easily removed intact endoscopically in 11 out of 12 cases. One 10-year-old boy in this group req uired open surgical removal of the stent. In one 35-year-old patient, the s tent was forgotten for 36 months. It had fractured spontaneously in 7 place s and required endoscopic and open removal of stent fragments. In 2 cases, a growing 9-year-old boy, and a 30-year-old man the stents were forgotten f or 46 and 48 months respectively. After 46 months of retaining the stent, t he stent spontaneously fractured in 11 places in the growing child, while i n the adult it became heavily calcified and fractured during attempts to re move it endoscopically. Two adult patients with moderate renal failure at t he time of stent insertion retained the stents for 40 and 60 months respect ively. One of these 2 stents had a minor calcification at the tip of the st ent in the renal pelvis. Both stents were removed intact endoscopically and showed no sign of fracture or calcification. Conclusion: In a growing child a prolonged forgotten 'J' stent is very like ly to undergo spontaneous fracture due to the stress exerted on it as a res ult of cranio-caudal growth of the child. In adults, prolonged forgotten st ents become calcified, brittle and lose tensile strength after more than on e year of placement and may fracture either spontaneously or during attempt s to remove them endoscopically. In patients producing hypotonic urine such as patients with moderate renal failure, a prolonged forgotten stent may r emain little affected by the passage of time.