Introduction
BK virus (BKV) is a member of the polyomavirus family, which was first
isolated in 1971 from the urine sample of a renal transplant patient,
with clinical observations made over the years, it was understood that
BKV is responsible for BKV nephropathy (BKVN) (1-3). The exact
prevalence of BKVN is not known, however, it is estimated to be in the
range of 1-15 %. BKVN is an important clinical problem causing graft
loss in 15-50 % of transplant patients (4). Risk factors for BKV are
aggressive immunosuppression, high human leukocyte antigen (HLA)
mismatch, ureteral stent use, rejection therapy, prolonged ischemia
duration, advanced age, male recipient, diabetes mellitus (DM),
lymphocyte depleting induction therapies, tacrolimus, and mycophenolate-
based regimens (5-10). It has been shown that the use of double-J-Stent
(DJS) in experimental animal models causes superficial epithelial
destruction, ulceration, and inflammatory changes on the transitional
epithelium in rat ureters, as well as increasing the incidence of BKVN
by 4 times (2,11-13). Studies have shown that conditions that cause
persistent hydronephroses, such as posttransplant ureter flexion and
ureteral stenosis, may play a dynamic role in the pathogenesis of
polyoma virus-associated nephropathy by causing ureteral reflux.
Vesicoureteral reflux (VUR) may occur with normal bladder contraction
while using DJS (14,15). In 2015, we compared the patients with
anti-reflux mechanism DJS (ARD-DJS) and those used standard DJS (st-DJS)
in terms of BKV and BKVN frequency in 90 kidney transplant patients in
two centers (Figure 1). In this study, BKV was observed with
significantly less frequency in univariate analyzes in patients with
ARD-DJS. However, no significant difference was observed in the
multivariate analyzes. In this study, the small number of cases and the
short follow-up duration were the factors limiting our study (13). With
the increase in the number of our patients over time and lengthening of
the follow-up duration, we needed to re-evaluate the data in one center.