Objectives To describe the incidence and management of haemolysis after transcatheter coil occlusion of the arterial duct.

Design Prospective clinical and echocardiographic follow up of patients who have undergone implantation of the Cook detachable duct occlusion coil.

Setting Tertiary paediatric cardiac centre.

Patients Five cases of haemolysis (two girls aged 6 and 11 months; three boys aged 6, 17, and 14 months) from a series of 137 duct coil implantations.

Main outcome measures The occurrence of clinically significant haemolysis after implantation of duct occlusion coils and resolution of haematuria after completion of duct occlusion.

Results Haemolysis was detected in five of 137 procedures following implantation of Cook detachable duct coils. Four patients became symptomatic 12 hours after the procedure but in one haemolysis was detected three months later. Resolution of ongoing haemolysis was achieved within 48 hours of detection with further coil implantations, but haematuria persisted for up to 10 days. In one patient the extensive destruction of erythrocytes resulted in acute renal failure requiring peritoneal dialysis.

Conclusions Haemolysis is an important complication after duct coil implantation. It occurred in 3.6% of 137 procedures in this series and is most likely to occur in young patients with relatively large ducts. Further coil implantation to occlude the duct completely is not only successful but technically relatively straightforward and should be undertaken early if major complications such as severe anaemia and renal failure are to be avoided.