RESUMEN
A 39-year-old para 0(+1) woman with known nephrolithiasis within a left-sided pelvic kidney presented with left-sided renal colic at 7 weeks gestation. She had a previous miscarriage due to a bicornuate uterus. Ultrasound and magnetic resonance urography confirmed an incomplete obstruction of the left upper renal tract which was relieved by percutaneous nephrostomy. She presented again at 14 weeks with renal colic and minimal output. An ultrasound confirmed recurrent hydronephrosis and a nephrostogram showed that the catheter had retracted almost completely from the collecting system. This was considered to be due to the upward pressure of the enlarging uterus on the catheter, which had been fixed externally to the skin. This problem was obviated by not securing the replacement nephrostomy tube to the skin. She developed pre-eclamptic toxaemia and gave birth at 35 weeks gestation by caesarean section. The calculus was later dissolved using extra-corporeal shockwave lithotripsy.
