Patent Ductus Arteriosus: A Medical-Legal Guide for Attorneys

Introduction

Patent ductus arteriosus (PDA) is the most common cardiac condition in newborn infants and one of the most extensively studied — yet least settled — problems in neonatology. The ductus arteriosus is a normal fetal blood vessel connecting the pulmonary artery to the aorta. In most full-term infants it closes within hours to days of birth. In premature infants, closure is frequently delayed, and the vessel may remain open for weeks (Ambalavanan et al., Pediatrics, 2025; Laughon et al., JAMA, 2026).

For attorneys, PDA occupies unusual medical-legal territory. Unlike many pediatric conditions where a clear national standard dictates a single correct action, PDA management is characterized by decades of unresolved controversy and legitimate clinical disagreement. Recent high-quality randomized trials have failed to show that closing the ductus improves the outcomes that matter most, and expert, guideline-informed clinicians reasonably choose observation, medication, or a procedure in similar situations. This means PDA cases frequently turn less on whether a "correct" treatment was withheld and more on whether the diagnosis was recognized, whether monitoring was adequate, whether an intervention was performed competently, and whether informed consent was obtained.

This guide explains the anatomy, natural history, current standards, and the most common allegations and defenses, so that legal professionals can evaluate liability and causation with appropriate context.

Clinical Vignette

The following scenario is entirely fictional and does not depict any real patient or case.

An infant is born at 25 weeks' gestation weighing 700 grams and is admitted to the neonatal intensive care unit (NICU). Over the first two weeks she requires escalating respiratory support. An echocardiogram on day 12 documents a moderate-to-large patent ductus arteriosus with left-to-right shunting and left atrial enlargement. The clinical team, citing recent evidence favoring conservative management, elects expectant observation. The infant's respiratory status fluctuates over the following weeks. A repeat echocardiogram at five weeks shows a persistent large shunt. A course of medication is attempted without closure, and the ductus is ultimately closed by a catheter-based procedure. The child later develops chronic lung disease and a neurodevelopmental delay.

A lawsuit alleges that the team should have treated the ductus earlier and more aggressively. The defense responds that expectant management was consistent with current evidence and guidelines, that pharmacologic and surgical closure have never been proven to reduce chronic lung disease or neurodevelopmental impairment, and that the child's outcomes are attributable to extreme prematurity itself. This hypothetical captures the core tension in nearly every preterm PDA case: distinguishing the consequences of prematurity from the consequences of any treatment decision.

What Is a Patent Ductus Arteriosus?

The ductus arteriosus is essential during fetal life, diverting blood away from the non-functioning lungs. After birth, as the lungs expand and oxygen levels rise, the vessel normally constricts and closes. When it does not, blood flows abnormally from the aorta (high pressure) into the pulmonary artery (low pressure) — a "left-to-right shunt."

The clinical consequences depend almost entirely on size and duration (Fadel et al., Echocardiography, 2015; Leshen et al., Pediatric Radiology, 2022):

• Small PDA: Often causes no significant shunting. Many patients remain asymptomatic for life, and the defect may be discovered incidentally.
• Moderate PDA: May be tolerated for years, sometimes presenting in adulthood with exercise intolerance or heart failure.
• Large PDA: Can cause significant volume overload of the left heart, pulmonary overcirculation, heart failure, and, over time, pulmonary hypertension.

Two distinct clinical populations dominate PDA litigation, and they must not be conflated:

• The premature infant — where PDA is common, often self-resolving, and where treatment is genuinely controversial.
• The term infant, child, or adult with an isolated PDA — where the defect is a discrete structural anomaly that is highly amenable to closure and where the "missed murmur" or failure-to-refer scenario is more relevant.

Natural History: Why "Watchful Waiting" Is Often Appropriate

A critical fact for any PDA case is that the ductus frequently closes on its own, even in extremely premature infants. As conservative management has become more common, roughly 90% of infants born at less than 26 weeks' gestation have been found to close the ductus spontaneously, at a median of approximately 36 weeks' postmenstrual age. Among infants discharged home with a persistent PDA, about 50% close by 9 months and 80% by 2 years (Ambalavanan et al., Pediatrics, 2025).

This natural history is the foundation of the modern conservative approach and a powerful defense theme: an untreated PDA that later closed on its own — or was closed later — does not, by itself, establish negligence.

Potential Complications

While many PDAs are benign, a hemodynamically significant PDA can contribute to serious complications, which frequently become the alleged injuries in litigation (Hamrick et al., Pediatrics, 2020; Mitra et al., Cochrane Database, 2023; Cepas-Guillén et al., Nature Reviews Cardiology, 2025):

• Pulmonary consequences: Pulmonary edema, pulmonary hemorrhage, prolonged mechanical ventilation, and possible contribution to bronchopulmonary dysplasia (chronic lung disease).
• Systemic hypoperfusion ("ductal steal"): Diversion of blood away from the body's organs, associated with necrotizing enterocolitis (a serious bowel injury), impaired kidney function, and reduced cerebral (brain) blood flow.
• Neurologic: Associations with intraventricular hemorrhage (bleeding in the brain), periventricular leukomalacia, and cerebral palsy.
• Cardiac: Left heart volume overload progressing to heart failure.
• Late complications (untreated moderate/large PDA): Progressive, eventually irreversible pulmonary hypertension (Eisenmenger physiology) and, historically, infective endarteritis (infection of the vessel).

A crucial causation caveat: These conditions are associated with PDA, but a direct causal link has not been established. Prematurity itself independently causes nearly all of these same complications. As the Cochrane reviewers note, the causal link between PDA and these adverse outcomes has not been demonstrated (Mitra et al., Cochrane Database, 2023). This distinction is the single most important concept in preterm PDA causation analysis.

Current Evidence-Based Standards of Care

The modern standard reflects a decisive shift away from aggressive routine treatment toward selective, individualized management. Attorneys should understand the following evidence-based anchors:

1. Diagnosis relies on echocardiography. Physical findings (the classic continuous "machine-like" murmur, bounding pulses) may be present, but echocardiography is essential to confirm the diagnosis and to assess hemodynamic significance (Ambalavanan et al., Pediatrics, 2025). A large or symptomatic PDA that is not investigated with echocardiography when clinically indicated is a defensible target of criticism.
2. Prophylactic and early treatment are no longer routinely recommended. Multiple clinical trials show a lack of benefit from prophylactic or early (before 2 weeks of age) medical closure compared with expectant management; the AAP therefore does not recommend them (Ambalavanan et al., Pediatrics, 2025). The Baby-OSCAR trial of early ibuprofen for large PDAs found no benefit for the primary outcomes (Gupta et al., NEJM, 2024), and a 2026 randomized trial found expectant management did not increase the incidence of death or bronchopulmonary dysplasia compared with active treatment (Laughon et al., JAMA, 2026).
3. Treatment of a persistent hemodynamically significant PDA is reasonable but not mandated. Beyond 2 weeks of age, the AAP notes there are insufficient data for firm recommendations; it is considered reasonable to attempt pharmacologic closure of a hemodynamically significant PDA, with ibuprofen as the preferred agent (acetaminophen or indomethacin acceptable) (Ambalavanan et al., Pediatrics, 2025).
4. There is a stepwise escalation. If a significant PDA persists despite pharmacologic therapy (typically up to two courses), or if medication is contraindicated, the infant may be considered for transcatheter (catheter-based) closure or surgical ligation. Surgical ligation has become less frequent as transcatheter closure has become more common (Ambalavanan et al., Pediatrics, 2025).
5. Medications are effective at closing the duct but have not been shown to change long-term outcomes. Ibuprofen, indomethacin, and acetaminophen close roughly 70%–80% of ducts, but none has been proven to reduce mortality or bronchopulmonary dysplasia (Laughon et al., JAMA, 2026; Ambalavanan et al., Pediatrics, 2025). Ibuprofen is generally preferred over indomethacin because of a better safety profile, with a lower risk of necrotizing enterocolitis and kidney injury (Ambalavanan et al., Pediatrics, 2025).

The overarching legal point: Because the field is defined by what the AAP calls "equipoise," a wide range of management choices — observation, medication, or procedure — can each fall within the standard of care for the same infant. This makes the standard-of-care analysis in preterm PDA cases unusually dependent on the specific clinical facts rather than on a single "right answer."

Litigation Targets: Common Allegations

Despite the equipoise surrounding treatment choice, several recurring fact patterns generate PDA litigation. These are the most common plaintiff theories:

In the Premature Infant

• Failure to diagnose or monitor — not obtaining echocardiography in an infant with clinical signs of a significant shunt or unexplained deteriorating respiratory status.
• Failure to recognize and respond to a hemodynamically significant PDA — allowing a large, symptomatic shunt to persist without any reassessment or plan.
• Medication administration errors — dosing errors, or administering a cyclooxygenase inhibitor (indomethacin/ibuprofen) despite a recognized contraindication (e.g., active bleeding, significant renal dysfunction, necrotizing enterocolitis, thrombocytopenia).
• Surgical/procedural complications — injury during ligation or transcatheter closure (e.g., recurrent laryngeal nerve injury causing vocal cord paralysis, chylothorax, ligation of the wrong vessel, device embolization, or coarctation).
• Post-ligation cardiovascular deterioration — failure to anticipate and manage the well-recognized hemodynamic instability that can follow surgical ligation.
• Informed consent failures — inadequate disclosure of the controversy, the option of continued observation, and the risks of each pathway.

In the Term Infant, Older Child, or Adult

• Failure to detect a murmur or investigate an abnormal exam, leading to delayed diagnosis.
• Failure to refer to pediatric cardiology when a PDA is suspected or documented.
• Delayed closure of a significant PDA allowing progression to pulmonary hypertension/Eisenmenger physiology — a serious, life-altering, and largely preventable outcome in this population, making delay in this group a stronger liability theory than in the preterm population.

Defense Themes

PDA litigation, particularly in preterm infants, offers unusually strong evidence-based defenses:

• Genuine clinical equipoise. Major guidelines explicitly acknowledge that the optimal strategy and timing are undefined, and that multiple approaches are acceptable (Ambalavanan et al., Pediatrics, 2025). A treatment decision cannot be negligent merely because a different reasonable choice existed.
• Conservative management is evidence-based, not neglect. Recent randomized trials support expectant management, and prophylactic/early treatment is no longer recommended (Gupta et al., NEJM, 2024; Laughon et al., JAMA, 2026). Observation is an affirmatively supported strategy, not an omission.
• Spontaneous closure is common. The high natural closure rate undercuts claims that any given untreated PDA required intervention (Ambalavanan et al., Pediatrics, 2025).
• Causation is the central weakness of most plaintiff claims. Because prematurity independently causes chronic lung disease, brain injury, necrotizing enterocolitis, and neurodevelopmental impairment, and because closing the ductus has not been shown to prevent these outcomes, it is difficult to prove that earlier or different PDA treatment would, more likely than not, have changed the outcome (Mitra et al., Cochrane Database, 2023; Laughon et al., JAMA, 2026).
• Treatment carries its own risks. Both medication (bleeding, renal injury, necrotizing enterocolitis) and surgical ligation (which may itself be an independent risk factor for worse neurodevelopmental outcomes) have documented harms, so a decision to withhold aggressive treatment can be affirmatively justified (Hamrick et al., Pediatrics, 2020).

Medical Causation

Causation is where most preterm PDA cases are won or lost. The key questions for expert analysis:

• Would earlier or different treatment, more likely than not, have changed the outcome? Given that closure has not been shown to reduce death, chronic lung disease, or neurodevelopmental impairment, this burden is difficult for plaintiffs to meet in the preterm population.
• Is the alleged injury attributable to the PDA or to prematurity? Disentangling these is essential and requires review of gestational age, birth weight, and the full complication profile.
• Was there a discrete, avoidable harm? In contrast to outcome-based claims, a procedural complication (e.g., a surgically transected nerve) or a medication error against a clear contraindication presents a much more direct and provable causal chain.

In the non-preterm population, the causation analysis is often stronger for plaintiffs: a large PDA left undiagnosed for years that progresses to irreversible pulmonary hypertension is a foreseeable and preventable outcome.

Common Misconceptions

• "A PDA always requires closure." False. Most PDAs in extremely premature infants close spontaneously, and treatment has not been shown to improve major outcomes.
• "Failure to treat a PDA caused this child's cerebral palsy (or chronic lung disease)." Unproven as a general matter. These conditions are driven by prematurity itself, and the causal link to the PDA has not been established.
• "A murmur was heard, so the diagnosis was obvious." Not necessarily — a large PDA may have little murmur, and echocardiography, not auscultation, defines hemodynamic significance.
• "The newer conservative approach means the old aggressive treatment was wrong." Standards evolve; care must be judged against the standard in effect at the time it was rendered, not by later evidence.
• "A small PDA is harmless, so nothing needed to be done." In the term/child/adult population, a persistent moderate-to-large PDA left untreated can cause serious late complications; the "harmless" framing applies mainly to genuinely small shunts.

Long-Term Outcomes and Damages

Alleged damages in PDA cases commonly include:

• Chronic lung disease (bronchopulmonary dysplasia) and prolonged respiratory support
• Neurodevelopmental impairment and cerebral palsy
• Necrotizing enterocolitis and its sequelae
• Complications of intervention (e.g., vocal cord paralysis, chylothorax, coarctation, device-related injury)
• Progressive pulmonary hypertension / Eisenmenger physiology (in delayed-diagnosis, non-preterm cases)
• Death

The magnitude of alleged damages is often large, which is precisely why the causation analysis — separating the consequences of prematurity from the consequences of any treatment decision — is so critical.

Medical Records That Matter

A meaningful PDA case review depends on the complete longitudinal record, including:

• Gestational age and birth weight documentation
• Serial echocardiogram reports (timing, shunt size, hemodynamic significance, left atrial/ventricular measurements)
• Daily respiratory support and ventilator records
• Medication administration records (agent, dose, timing, contraindication screening)
• Operative and catheterization procedure notes
• Post-procedure hemodynamic monitoring
• Nursing flow sheets and vital-sign trends
• Consultant (neonatology, pediatric cardiology, cardiac surgery) notes
• Informed consent documentation
• Longitudinal neurodevelopmental follow-up

Isolated records rarely tell the full story; the interplay between prematurity, respiratory course, and ductal status only emerges from the complete chart.

The Role of Pediatric and Cardiology Expertise

PDA sits at the intersection of neonatology, pediatric cardiology, and — where intervention occurs — congenital cardiac surgery and interventional cardiology. Because the standard of care here is defined by equipoise rather than by a bright-line rule, expert review is essential to:

• Interpret echocardiographic hemodynamic significance
• Explain the applicable standard of care at the time care was rendered
• Distinguish the consequences of prematurity from those of the PDA or its treatment
• Assess whether a procedural complication reflects a recognized risk or a deviation
• Evaluate informed consent adequacy
• Provide objective, evidence-based opinions grounded in current literature

Key Takeaways for Attorneys

• PDA management is defined by genuine controversy and equipoise — multiple approaches (observation, medication, procedure) can each meet the standard of care for the same infant.
• The population matters. Preterm PDA (common, often self-resolving, controversial) is legally distinct from term/child/adult PDA (a discrete, closable structural defect).
• Spontaneous closure is common, even in extremely premature infants, undermining claims that any untreated PDA required intervention.
• Closure has not been shown to reduce mortality, chronic lung disease, or neurodevelopmental impairment — a decisive fact for causation in preterm cases.
• Prematurity independently causes most of the injuries alleged in these cases; separating the two is the crux of causation.
• The strongest liability theories are discrete and provable: procedural complications, medication errors against clear contraindications, missed diagnosis with failure to refer, and inadequate informed consent.
• In non-preterm patients, delayed diagnosis allowing progression to pulmonary hypertension is a more compelling plaintiff theory.
• Care must be judged against the standard in effect at the time, given how rapidly PDA practice has shifted toward conservative management.
• Echocardiography, not the murmur, defines hemodynamic significance.
• The complete longitudinal record and qualified expert review are indispensable to distinguish unavoidable outcomes from potentially preventable injury.

References

1. Ambalavanan et al. Pediatrics. 2025.
2. Laughon et al. JAMA. 2026.
3. Fadel et al. Echocardiography. 2015.
4. Leshen et al. Pediatric Radiology. 2022.
5. Hamrick et al. Pediatrics. 2020.
6. Mitra et al. Cochrane Database. 2023.
7. Cepas-Guillén et al. Nature Reviews Cardiology. 2025.
8. Gupta et al. New England Journal of Medicine. 2024.