Background Patent ductus arteriosus (PDA) in preterm infants is often assessed with echocardiographic parameters, especially colour Doppler ductal diameter and pulsed Doppler flow pattern. Clinical algorithms have been proposed in which PDA treatment is indicated by either large diameter or a particular flow pattern, however it is unknown whether ductal diameter and flow pattern provide equivalent stratification of infants.

Aim Retrospectively assess both parameters in 197 echocardiograms from 104 infants (gestational age <31 weeks).

Methods Echocardiograms were independently reviewed and the internal colour Doppler diameter of the PDA and the pulsed Doppler flow pattern were characterised for each study (169 records had both parameters recorded).

Results Diameter varied widely within each group but was significantly associated with flow pattern: mean diameter was greatest in the pulmonary hypertension (PH) group (2.6 mm), progressively narrowed across growing and pulsatile groups, and was smallest in the closing group (1.3 mm). When echocardiograms were categorised using previously published diameters, 82.4% of the PH group had diameters >2.0 mm, large diameters predominated in the growing and pulsatile groups but to a progressively smaller extent, and 98.1% of closing group had diameters <2.0 mm.

Conclusion Ductal diameter and flow patterns are significantly associated, consistent with a narrowing of the ductus until closure. Overall, the two parameters are in good agreement but will result in different treatment decisions in some cases. Clinicians might consider using both methods as a cross check against each other, to assist in the management of preterm infants with a clinically detectable PDA.