Objective: To explore whether complete courses of indomethacin were necessary to close patent ductus arteriosus (PDA).

Methods: Babies born <30 weeks gestation were assessed in the first 12 h of life and treated with indomethacin (0.1 mg/kg) if the PDA was >1.6 mm in diameter. With consent, they were randomly assigned before the second dose to indomethacin (to receive two more doses of indomethacin at 0.1 mg/kg irrespective of ECHO findings) or to ECHO (further doses only if PDA was >1.6 mm). Babies had serial echocardiography to day 28. Important clinical outcomes and complications of indomethacin were monitored. The primary outcome was PDA closure.

Results: 74 babies were enrolled: 34 to ECHO, 40 to indomethacin. Groups were comparable at study entry. PDA closure was similar (74%). Failure of closure occurred in 10 (25%) indomethacin and nine (26%) ECHO. Reopening of the ductus arteriosus requiring a further course of indomethacin was similar, nine (23%) indomethacin versus six (18%) ECHO. One baby in the ECHO arm required a third course. Surgical ligation was similar: two (5%) indomethacin versus one (3%) ECHO. More doses of indomethacin were given to the indomethacin arm, median three (range 1–12) versus median one, (range 1–15), p<0.0001. 21 (64%) babies in the ECHO arm received one dose of indomethacin. No significant differences were seen in clinical outcomes. There were trends to increased pulmonary haemorrhage, chronic lung disease and renal impairment in the indomethacin arm.

Conclusion: These data suggest the selective duration of indomethacin treatment may be as effective in achieving PDA closure and offers potential for dose minimisation and reduction of adverse effects.