Dwell time of percutaneous nephrostomies in pregnancy – what is the optimal exchange interval?

If procedural intervention is indicated, options for management of obstructive uropathy in pregnancy include ureteric stenting, primary ureteroscopy (for calculi), or percutaneous nephrostomy. Early encrustation/blockage of nephrostomy tubes in pregnancy has been described, due to glomerular hyperfiltration/hypercalcuria. Some authors describe shorter exchange intervals (i.e. 3-weekly), while AUA guidelines recommend exchange 4–6 weekly. This study aims to evaluate outcomes of nephrostomy insertion during pregnancy in a tertiary centre in Melbourne, Australia. Seventeen patients underwent percutaneous nephrostomy insertion during pregnancy from 2013 to 2023, in a tertiary centre in Melbourne, Australia. Data collected retrospectively included indication for nephrostomy, radiation exposure, dwell time, blockage/dislodgement rates, urological and obstetric outcomes. Of 17 pregnant patients, indication for nephrostomy included ureteric calculus (n = 13), transplant hydronephrosis (n = 1), ureteric clot obstruction (n = 1), obstructive cervical malignancy (n = 1), and infected PUJO (n = 1). Mean age was 32.5 years (SD 5.7 years), whilst mean gestation stage was 25.0 weeks (SD 9.4 weeks). Regarding radiation exposure – mean DAP was 219.7 uGym2, mean air kerma 33.6 mGy, and mean fluoroscopy time 1.5 min. Mean nephrostomy dwell time was 37.45 days/5.35 weeks (SD 25.1 days), while median dwell time was 31 days (IQR 21.5–45 days). There were no peri-procedural urological or major obstetric complications. In our pregnant cohort (albeit small), mean nephrostomy dwell time was notably greater than previously described (5.35 weeks in our cohort vs. ~ 3 weeks in the literature). This finding aligns with AUA guidelines for nephrostomy exchange 4–6 weekly in pregnancy. Larger volume prospective data is required to establish appropriate exchange intervals for nephrostomies in pregnancy.