Patent ductus arteriosus in preterm infants

Overview & Definition

A 26-week infant, three days old, ventilated for respiratory distress syndrome, is weaning nicely. Over the next 48 hours the team notice bounding pulses, a widened pulse pressure, and a creeping oxygen and ventilator requirement. The echocardiogram shows a 2 mm duct with left-to-right flow and diastolic flow reversal in the descending aorta. This is the classic presentation of a patent ductus arteriosus (PDA) becoming haemodynamically significant, and the decisions made here are some of the most contested in modern neonatology. ^{[13] [7]}

The ductus arteriosus is the fetal vessel connecting the main pulmonary artery to the descending aorta. In utero it shunts the right ventricular output away from the high-resistance lungs and toward the placenta. After birth it is meant to close — first functionally, by smooth muscle contraction within hours, then anatomically, by intimal proliferation over two to three weeks, leaving the ligamentum arteriosum. A PDA in the preterm context is persistent patency beyond this expected window. It is not a congenital malformation in the usual sense; it is the predictable consequence of an immature ductal wall meeting the postnatal circulation. ^{[7] [14]}

The distinction that governs all management is between a PDA that is merely present and one that is haemodynamically significant — a substantial left-to-right shunt producing measurable pulmonary over-circulation and systemic hypoperfusion. Most preterm ducts stay open for a while and most close on their own; only a minority cause the end-organ compromise that justifies treatment. Holding the question "is this duct significant?" at the centre of every assessment is the single most important habit for this topic, because the evidence base of the last decade has remorselessly dismantled the older reflex of closing every duct. ^{[1] [11]}

The modern story of the preterm PDA is a story of restraint winning over intervention. Three decades of trials — from prophylactic indomethacin to early ibuprofen to the BeNeDuct trial of expectant management — have shown that routine closure does not improve survival without bronchopulmonary dysplasia, does not improve long-term neurodevelopment, and carries real harms. The fellowship candidate who can articulate why practice shifted, and name the trials, will answer this topic well. ^{[1] [6] [11]}

References14ShowHide

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2. [2]Mitra S, Florez ID, Tamayo ME, et al Association of Placebo, Indomethacin, Ibuprofen, and Acetaminophen With Closure of Hemodynamically Significant Patent Ductus Arteriosus in Preterm Infants: A Systematic Review and Meta-analysis. JAMA, 2018.PMID 29584842
3. [3]Ohlsson A, Walia R, Shah SS Ibuprofen for the treatment of patent ductus arteriosus in preterm or low birth weight (or both) infants. Cochrane Database Syst Rev, 2020.PMID 32045960
4. [4]Jasani B, Mitra S, Shah PS Paracetamol (acetaminophen) for patent ductus arteriosus in preterm or low birth weight infants. Cochrane Database Syst Rev, 2022.PMID 36519620
5. [5]Fowlie PW, Davis PG, McGuire W Prophylactic intravenous indomethacin for preventing mortality and morbidity in preterm infants. Cochrane Database Syst Rev, 2010.PMID 20614421
6. [6]Clyman RI, Liebowitz M, Kaempf J, et al PDA-TOLERATE Trial: An Exploratory Randomized Controlled Trial of Treatment of Moderate-to-Large Patent Ductus Arteriosus at 1 Week of Age. J Pediatr, 2019.PMID 30340932
7. [7]Benitz WE Patent Ductus Arteriosus in Preterm Infants. Pediatrics, 2016.PMID 26672023
8. [8]Liebowitz M, Kaempf J, Erdeve O, et al Comparative effectiveness of drugs used to constrict the patent ductus arteriosus: a secondary analysis of the PDA-TOLERATE trial. J Perinatol, 2019.PMID 30850756
9. [9]Liebowitz M, Katheria A, Sauberan J, et al Lack of Equipoise in the PDA-TOLERATE Trial: A Comparison of Eligible Infants Enrolled in the Trial and Those Treated Outside the Trial. J Pediatr, 2019.PMID 31255386
10. [10]Weisz DE, McNamara PJ Patent ductus arteriosus ligation and adverse outcomes: causality or bias? J Clin Neonatol, 2014.PMID 25024972
11. [11]Mitra S, Scrivens A, Fiander M, et al Early treatment versus expectant management of hemodynamically significant patent ductus arteriosus for preterm infants. Cochrane Database Syst Rev, 2025.PMID 40548426
12. [12]Mitra S, de Boode WP, Weisz DE, et al Interventions for patent ductus arteriosus (PDA) in preterm infants: an overview of Cochrane Systematic Reviews. Cochrane Database Syst Rev, 2023.PMID 37039501
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14. [14]Chorne N, Jegatheesan P, Lin E, et al Risk factors for persistent ductus arteriosus patency during indomethacin treatment. J Pediatr, 2007.PMID 18035143