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PATENT DUCTUS ARTERIOSUS IN PRETERM NEONATES

A Comprehensive Evidence-Based Teaching Session

For DM/DrNB Neonatology & MD Pediatrics Residents

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TABLE OF CONTENTS

1. Embryology and Fetal Circulation
2. Physiology of Ductal Closure After Birth
3. Pathophysiology of PDA in Preterm Infants
4. Epidemiology
5. Definition of Hemodynamically Significant PDA
6. Clinical Manifestations
7. How to Suspect PDA in the NICU
8. Echocardiography
9. Investigations
10. Complications of Untreated PDA
11. Current Controversies
12. Management Algorithm
13. Conservative Management
14. Medical Treatment - Drug Comparison
15. Drug-Specific Mechanisms and Adverse Effects
16. Surgical and Catheter Closure
17. Special Situations
18. Landmark Trials
19. Current Guideline Recommendations
20. One-Page Management Algorithm
21. Drug Comparison Table
22. 30 High-Yield MCQs
23. Consultant-Level Summary
24. Top 20 Exam Points

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SECTION 1: EMBRYOLOGY AND FETAL CIRCULATION

Developmental Anatomy

Fetal Circulation - Why the Ductus is Essential

Right Ventricle → Pulmonary Artery → [high PVR] 
                                    ↓ (most blood bypasses lungs)
                               Ductus Arteriosus 
                                    ↓
                           Descending Aorta → Placenta (for oxygenation)

What Keeps the Ductus Open in Fetal Life?

1. Prostaglandin E2 (PGE2) - produced locally in the ductal wall and supplied by the placenta. Acts on EP4 receptors → activates adenylyl cyclase → increases cAMP → smooth muscle relaxation and ductal dilation.
2. Prostaglandin I2 (PGI2, prostacyclin) - similar mechanism.
3. Low oxygen tension - fetal PaO2 is approximately 20-30 mmHg. Low oxygen reduces voltage-gated K+ channels and promotes smooth muscle relaxation.
4. Adenosine - promotes relaxation.
5. Nitric oxide (NO) - contributes to ductal relaxation.

Structural Composition

• Rich in smooth muscle arranged in a spiral, intimal cushions pattern
• Sparse elastic tissue compared to the aorta
• This smooth muscle is what contracts at birth to produce functional closure
• The preterm DA has less smooth muscle, more gelatinous matrix, and fewer oxygen-sensing channels - explaining its resistance to closure

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SECTION 2: PHYSIOLOGY OF DUCTAL CLOSURE AFTER BIRTH

Two-Phase Closure

Triggers at Birth

Molecular Mechanism of O2-mediated Closure

Timeline of Normal Closure

What Opposes Closure in Preterm Infants?

1. Immature O2-sensing (Kv channels not fully expressed)
2. Persistent prostaglandin sensitivity (EP4 receptor upregulation)
3. Higher circulating PGE2 (immature pulmonary metabolism)
4. Lower platelet-derived thromboxane (platelets are important in mechanical plugging of the ductus)
5. Relative hypoxemia (often due to RDS)
6. Structural immaturity of ductal smooth muscle
7. Elevated PGE2 from endotracheal tube inflammation

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SECTION 3: PATHOPHYSIOLOGY OF PDA IN PRETERM INFANTS

The Central Problem: Left-to-Right Shunting

LEFT VENTRICLE
     ↓ (high pressure)
   AORTA
     ↓
   PDA ← (blood stolen here - "ductal steal")
     ↓
 PULMONARY ARTERY
     ↓
   LUNGS (already receiving normal cardiac output)
     ↓ (LUNG FLOODING)
 PULMONARY VEINS
     ↓
 LEFT ATRIUM → LEFT VENTRICLE (volume overload)

Two Simultaneous Problems

• Pulmonary blood flow increases (can be 2-4x normal)
• Pulmonary edema → impaired gas exchange
• Increased ventilator requirements
• Risk of pulmonary hemorrhage
• Long-term: BPD

• Diastolic blood pressure falls (wide pulse pressure)
• Retrograde diastolic flow in descending aorta
• Gut ischemia → NEC risk
• Renal hypoperfusion → AKI, oliguria
• Cerebral autoregulation loss → IVH
• Coronary steal → myocardial ischemia

Mnemonic for PDA Consequences: "BRAIN GUT KIDNEY LUNG"

• Brain - IVH, PVL, altered autoregulation
• Renal - AKI, oliguria, Na wasting
• Airway/Lung - pulmonary hemorrhage, BPD, edema
• Intestine - NEC, feed intolerance
• Nutrition - growth failure (from fluid restriction + increased work of breathing)
• Gut - mesenteric steal, necrotizing enterocolitis
• Utility - all systems compromised (multi-organ dysfunction)
• Terminal - mortality in untreated massive shunts

Why the Preterm Myocardium is Vulnerable

• Immature myocyte calcium handling
• Less myofibril content per unit mass
• Operates near maximum of Starling curve at baseline
• Cannot significantly increase stroke volume → compensates with tachycardia only

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SECTION 4: EPIDEMIOLOGY

Incidence by Gestational Age

Incidence by Birth Weight

Risk Factors

• Prematurity (inversely proportional to GA) - strongest risk factor
• Respiratory distress syndrome (RDS) - hypoxemia opposes closure
• Early surfactant therapy (paradoxically exposes a previously hidden PDA by reducing PVR acutely)
• Sepsis/infection
• Twin-twin transfusion (recipient twin)
• Intrauterine growth restriction
• Genetic (TFAP2B mutation, chromosomal anomalies - Trisomy 21, Turner)
• Elevated altitude, Rubella (congenital)

• Male sex (slightly higher risk in preterm, opposite of term where F:M = 2:1)
• Fluid overload in first days
• Thrombocytopenia (platelets normally help seal the ductus)
• Anemia (increases shunt flow)
• Low antenatal steroids coverage

Protective Factors

Natural History and Spontaneous Closure

• Among infants born 23-28 weeks: 73% with an open DA at 7 days will close spontaneously by 44 weeks postmenstrual age (Benitz, Pediatrics 2010)
• Among infants with hsPDA at day 3, ~50-60% close without treatment by 28 days
• The PDA-TOLERATE trial (Clyman et al, 2019): conservative management vs treatment - no difference in outcomes, but most PDAs closed eventually
• BeNeDuctus (NEJM 2023): spontaneous closure rate in expectant management group was substantial enough to achieve non-inferiority

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SECTION 5: DEFINITION OF HEMODYNAMICALLY SIGNIFICANT PDA (hsPDA)

Why There Is No Universal Definition

Clinical Criteria for hsPDA

• Persistent or worsening respiratory failure (increased FiO2, increased MAP, unable to wean ventilator, or reintubated)
• Persistent hypotension (requiring inotropes)
• Pulmonary hemorrhage
• Metabolic acidosis
• Feeding intolerance with concern for gut ischemia
• Bounding pulses with wide pulse pressure (>25 mmHg)
• Hyperactive precordium
• Continuous or systolic murmur at upper left sternal border

Echocardiographic Criteria for hsPDA

Detailed Echo Interpretation

LA:Ao Ratio (Left Atrial to Aortic Root Ratio)

• Measured in parasternal long axis
• Reflects degree of pulmonary venous return → increased LA size with large L-R shunt
• Normal: 0.8-1.2
• Mild PDA: 1.2-1.5
• Significant PDA: >1.5
• Severe: >2.0
• Limitation: LA:Ao ratio is load-dependent; may be normal early when LA compliance is good

Ductal Diameter

• Measured by color Doppler or 2D (parasternal short axis or high parasternal)
• <1.5 mm = small/restrictive (usually not hemodynamically significant)
• 1.5-2.0 mm = moderate

• 2.0 mm = large

• Pearl: In ELBW infants even 1.5 mm is large relative to body size

Ductal Flow Pattern (Pulsed Wave Doppler)

Descending Aortic Flow (Diastolic)

• Normally: forward diastolic flow (>0 cm/s) in descending aorta
• With significant PDA: retrograde (reverse) diastolic flow
• Grade 0: Normal forward flow
• Grade 1: Absent diastolic flow
• Grade 2: Retrograde diastolic flow
• Grade 3: Bidirectional flow (severe steal)

Superior Vena Cava (SVC) Flow

• Reflects cerebral and upper body venous return
• Normal: 40-120 mL/kg/min
• Low SVC flow (<40 mL/kg/min) = poor cerebral perfusion → high risk of IVH
• Associated with worse neurodevelopmental outcomes

LV Output

• Normal: 150-300 mL/kg/min
• In significant PDA: >300 mL/kg/min (hyperdynamic) because LV must pump both systemic AND recycled pulmonary blood
• Very high LVO (>500 mL/kg/min) suggests massive shunt

Mesenteric/Celiac Flow

• In hsPDA: retrograde diastolic flow in SMA or celiac axis
• Correlates with NEC risk
• Doppler resistance index (RI) and pulsatility index (PI) are elevated

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SECTION 6: CLINICAL MANIFESTATIONS

Early Signs (First 24-72 hours)

• Inability to wean ventilator after surfactant - "the baby who should be getting better but isn't"
• Mild tachycardia
• Subtle widening of pulse pressure
• A soft systolic murmur at upper left sternal border (not always present)
• Slight hepatomegaly (early fluid overload)

Late/Overt Signs (>72 hours, classical presentation)

• Bounding pulses (radial, femoral, dorsalis pedis) - due to wide pulse pressure
• Hyperactive precordium - palpable at the lower left sternal border or even through the mattress
• Continuous "machinery" murmur at upper left sternal border (but often systolic only in preterm)
• Tachycardia (compensatory)
• Wide pulse pressure (systolic high, diastolic low - e.g., 70/20 = PP of 50)
• Gallop rhythm (S3 or summation gallop) in severe cases

• Increased FiO2 requirements
• Increased MAP/PEEP requirements
• Recurrent desaturation episodes
• CO2 retention
• Pulmonary hemorrhage (pink frothy secretions from ETT - emergency)

• Metabolic acidosis (base deficit worsening)
• Lactic acidosis
• Oliguria (urine output <1 mL/kg/h)
• Prolonged capillary refill time (>3 seconds)
• Pallor, mottling

• Increased gastric residuals
• Abdominal distension
• Blood in stools (if mesenteric ischemia)
• Inability to advance feeds

• IVH (often Grade 3-4) on day 3-4 cranial ultrasound
• Periventricular leukomalacia (PVL)
• Jitteriness, hypotonia
• Seizures (if severe)

Mnemonic for Clinical Features: "BOUNDING PULSES"

• Bounding peripheral pulses
• Overactive precordium
• Unable to wean ventilator
• Need for increased FiO2
• Diastolic blood pressure low (wide PP)
• Intolerance of feeds
• Necrotizing enterocolitis risk
• Gallop rhythm/murmur
• Pulmonary hemorrhage
• Urine output reduced
• Lactic acidosis/metabolic acidosis
• Systolic murmur at upper left sternal border
• Edema/hepatomegaly
• Sepsis-like picture (in severe cases)

NEC Association

1. DA steal → retrograde diastolic flow in SMA/celiac → gut ischemia
2. Fluid restriction (part of conservative management) → relative gut underperfusion
3. Vasoconstriction from indomethacin → direct NEC risk
4. Note: ibuprofen has less NEC risk than indomethacin; paracetamol has least NEC risk

Renal Effects

1. Ductal steal → reduced renal perfusion pressure
2. Indomethacin treatment → prostaglandin-mediated renal arteriolar dilation lost → renal vasoconstriction → AKI
3. Fluid restriction → reduced intravascular volume
4. Catecholamine excess (compensatory) → afferent arteriolar constriction

Neurological Effects

• Low SVC flow (<40 mL/kg/min) predicts IVH (grade 3-4)
• Impaired cerebral autoregulation → pressure-passive cerebral blood flow
• Fluctuating cerebral blood flow velocity on Doppler → risk of periventricular hemorrhage
• Indomethacin: reduces cerebral blood flow (used intentionally for IVH prophylaxis in some centers, but this effect is also potentially harmful in a sick infant)

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SECTION 7: HOW TO SUSPECT PDA IN THE NICU

Daily Bedside Assessment Protocol

DAILY PDA CHECKLIST (Bedside)
==============================
1. Pulse check: radial + femoral + dorsalis pedis
   → Bounding? Volume? 
2. Precordium: hyperactive?
3. Auscultation: murmur? where? systolic/continuous?
4. BP: pulse pressure >25 mmHg?
5. Respiratory: FiO2 trend (up or down)? Unable to wean?
6. Urine output: < 1 mL/kg/hr?
7. CXR (if done): cardiomegaly? Pulmonary plethora?
8. Feeds: gastric residuals, distension?

Which Babies Require Screening Echo?

• All infants <28 weeks at 24-72 hours of life (targeted neonatal echo by trained neonatologist)
• Any infant <34 weeks with clinical signs of PDA
• Any infant with pulmonary hemorrhage
• Any infant deteriorating despite surfactant (consider PDA as cause)
• Before starting indomethacin/ibuprofen (confirm PDA and exclude ductal-dependent CHD)

• Infants >32 weeks with no clinical signs
• Infants with congenital heart disease already under cardiology care
• Infants who have already had PDA confirmed and are on treatment

Clinical Scoring Systems

Differential Diagnosis

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SECTION 8: ECHOCARDIOGRAPHY IN PDA

The Trained Neonatologist Approach - "Targeted Neonatal Echocardiography (TNE)"

• Parasternal short axis: identify DA between MPA bifurcation and aortic arch
• Color Doppler: show L→R flow
• Measure diameter at pulmonary end (narrowest)

• PW Doppler through DA
• Peak velocity, direction, bidirectionality
• Calculate pressure gradient (4V²)

• M-mode or 2D in parasternal long axis
• Freeze frame at end-systole (when LA is largest)

• LV output = HR × (LVOT area × LVOT VTI)
• Shortening fraction (normal 28-40%)

• If TR present: RV pressure from TR jet = 4(Vmax)² + CVP
• R/L DA flow suggests relative PA vs. aortic pressure

• SVC flow (subcostal 4-chamber + pulsed Doppler)
• Descending aorta diastolic flow (abdominal aorta)
• SMA/celiac Doppler if NEC concern

• Before any treatment, ensure pulmonary blood flow is not ductal-dependent (pulmonary atresia) and systemic blood flow is not ductal-dependent (hypoplastic left heart, critical aortic stenosis, coarctation)
• Closing a duct in a ductal-dependent lesion = lethal

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SECTION 9: INVESTIGATIONS

Chest X-Ray

ECG

• Limited utility in acute PDA
• May show: sinus tachycardia, LV hypertrophy (tall R in V5-V6, deep S in V1), LA enlargement (notched P wave in lead II, biphasic P in V1)
• Useful to exclude arrhythmia as cause of hemodynamic deterioration

BNP / NT-proBNP

• NT-proBNP has better sensitivity and specificity than BNP for hsPDA
• Cutoff of NT-proBNP >2000 pg/mL at 48-72 hours has sensitivity ~85%, specificity ~80%
• Not a replacement for echocardiography - used as an adjunct to triage who needs echo urgently
• Also elevated in: infection, RDS, CHD - so must interpret in clinical context
• Trend more useful than single value

Troponin

• Elevated in myocardial injury from severe PDA
• Research tool; not standard clinical use
• May identify infants at highest risk for cardiac failure

Near-Infrared Spectroscopy (NIRS)

• Measures regional oxygen saturation (rSO2) of cerebral and mesenteric tissues
• In significant PDA: cerebral rSO2 typically elevated (due to increased cerebral blood flow from pulmonary steal → relative cerebral hyperemia OR decreased autoregulation)
• Mesenteric rSO2 may be reduced (gut steal from diastolic flow reversal)
• Cerebral-mesenteric rSO2 difference >10% may suggest hemodynamic compromise
• Evidence strength: Weak (observational studies only)
• Useful for trend monitoring during treatment
• Cannot diagnose PDA independently

Laboratory Findings in PDA

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SECTION 10: COMPLICATIONS OF UNTREATED PDA

Pulmonary Complications

• Mechanism: Left atrial hypertension → pulmonary venous hypertension → interstitial → alveolar edema
• Clinical: Increasing FiO2, increased ventilator settings, crackles, deteriorating CXR

• Emergency complication
• Mechanism: Extreme pulmonary overcirculation → hydrostatic pressure overwhelms alveolar-capillary barrier → hemorrhagic alveolar edema
• Early surfactant treatment paradoxically increases pulmonary hemorrhage risk because it rapidly drops PVR and unmasks a large shunt
• Management: Increase PEEP immediately (5-8 cmH2O) to compress pulmonary capillaries; urgent indomethacin (if not contraindicated); consider emergency ligation

• Pulmonary overcirculation → recurrent alveolar flooding → oxygen toxicity + barotrauma + volutrauma → BPD
• However, the PDA-TOLERATE and Baby-OSCAR trials suggest that treating PDAs early does not reduce BPD rates - challenging simple causation assumption

Neurological Complications

• Mechanism: Fluctuating cerebral blood flow (hypoperfusion-reperfusion) + impaired autoregulation + low SVC flow
• PDA is associated with grade 3-4 IVH
• Indomethacin reduces IVH but not by improving hemodynamics - rather by direct vasoconstrictive effect on cerebral vessels (a double-edged sword)

• White matter injury from cerebral ischemia
• Associated with low SVC flow states

Gastrointestinal: NEC

• As explained: diastolic steal from mesenteric vasculature → gut ischemia
• The relationship is complex: indomethacin INCREASES NEC risk, yet PDA itself increases NEC risk - making management decisions difficult

Renal: AKI

• Multifactorial: hemodynamic AKI from low renal perfusion + drug toxicity (indomethacin)
• Defined as: creatinine rise >26.5 μmol/L in 48h, or >1.5x baseline, or urine output <0.5 mL/kg/hr

Growth Failure

• Fluid restriction → calorie restriction → poor somatic growth
• Increased work of breathing → increased caloric expenditure
• Feed intolerance → reduced enteral nutrition

Mortality

• Schwartz's Surgery: "The estimated death rate for infants with isolated, untreated PDA is approximately 30%." (This applies to term infants with large untreated PDAs - not to the preterm NICU population context)
• In preterm infants: PDA is a contributing factor to mortality, but rarely the sole cause. The 2026 JAMA PDA-RCT found higher mortality in the actively treated group (9.6%) vs expectant management (4.1%) - a striking reversal of older thinking

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SECTION 11: CURRENT CONTROVERSIES

The Great Paradigm Shift (2015-2026)

• PDA is pathological and must be closed
• All significant PDAs → medical treatment → surgical ligation if medical fails
• Indomethacin prophylaxis in ELBW infants routinely done
• Surgical ligation rate ~4.4% (2014 data)

• PDA is part of the normal developmental spectrum in very preterm infants
• Most will close spontaneously if you support the infant
• Active treatment does not improve outcomes (BPD, death)
• Active treatment may increase mortality (PDA-RCT, JAMA 2026)
• Surgical ligation rate dropped to 0.84% (2021 national data)

Why Did Practice Change?

1. PDA-TOLERATE trial (Clyman, 2019): Infants with hsPDA randomized to treatment vs. conservative management. No difference in BPD, death, NEC, IVH. Confirmed feasibility of conservative approach.
2. BeNeDuctus trial (NEJM, December 2022, published 2023): 273 infants <28 weeks with echo-confirmed PDA (>1.5 mm) randomized to expectant management vs early ibuprofen. Expectant management was NON-INFERIOR - primary outcome (NEC + BPD + death) occurred in 46.3% expectant vs 63.5% ibuprofen. Expectant was actually better for BPD!
3. Baby-OSCAR trial (NEJM, January 2024): 653 infants 23-28 weeks with large PDA randomized to early ibuprofen vs placebo. No difference in death or BPD. Trend toward higher mortality in ibuprofen group.
4. PDA-RCT (JAMA, December 2025/February 2026): 482 infants 22-28 weeks randomized to expectant management vs active treatment (any of: acetaminophen, ibuprofen, indomethacin). Stopped early for FUTILITY and SAFETY. No difference in death + BPD (primary outcome). But mortality was significantly higher with active treatment: 9.6% vs 4.1% (p=0.01). Infections causing death: 3.8% active vs 0.8% expectant.
5. Cochrane: Early treatment vs. expectant management (Mitra, June 2025): 10 RCTs, 2035 infants. Active treatment associated with significantly higher composite death or BPD (56.2% vs 50.8%, RR 1.10), and higher mortality (14.3% vs 11.2%, RR 1.27).
6. AAP Clinical Report (Ambalavanan et al., 2025):
   • Prophylactic treatment NOT recommended
   • Early routine treatment NOT recommended
   • Conservative management is first-line
   • Selective treatment after 2 weeks for persistent hsPDA may be reasonable
   • Ibuprofen preferred over indomethacin

The Interpretive Challenge

1. Drug toxicity: Indomethacin/ibuprofen cause renal impairment, reduce mesenteric perfusion → AKI, NEC, infections
2. Unnecessary treatment: Many PDAs in the "treated" group would have closed spontaneously - these infants received unnecessary drug exposure
3. Selection bias in older studies: Old "successful" treatment trials defined success as PDA closure, not patient outcomes
4. Post-ligation cardiac syndrome: Surgical ligation causes its own complications
5. The PDA may be protective: In some very sick preterm infants, the PDA acts as a "pop-off valve" for RV in pulmonary hypertension. Closing it acutely can precipitate acute RV failure.

Genuine Remaining Indications for Active Treatment

• Pulmonary hemorrhage due to PDA - urgent treatment needed
• Hemodynamically unstable infant despite optimal conservative management with clear echo evidence of large hsPDA driving instability
• Infants unable to wean from high-frequency ventilation due to PDA
• Persistent hsPDA beyond 2-3 weeks of age despite full conservative management

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SECTION 12: MANAGEMENT ALGORITHM (Detailed)

PRETERM INFANT ≤32 WEEKS OR ≤1500g
           │
           ▼
    RISK STRATIFICATION AT BIRTH
    (GA, BW, antenatal steroids, RDS severity)
           │
     ┌─────┴─────┐
     │ >28 weeks  │    │  ≤28 weeks  │
     │ No RDS     │    │  or RDS     │
     └─────┬─────┘    └──────┬──────┘
           │                 │
    Clinical monitoring    Echo at 24-72h
    Daily assessment       (TNE by neonatologist)
           │                 │
    ┌──────┴─────────────────┴──────┐
    │     ECHO ASSESSMENT            │
    │  Small PDA? (<1.5mm, restrict) │
    └───────────────┬────────────────┘
                    │
         ┌──────────┼───────────┐
    Small PDA    Moderate    Large/hsPDA
    (<1.5mm)    (1.5-2mm)    (>2mm + clinical signs)
         │           │              │
    Observe    Observe +      CONSERVATIVE Mx
    Repeat if  serial echo    (see below)
    clinical      │              │
    deterioration  │         Response?
                   │         ┌───┴───┐
                           YES    NO
                            │      │
                         Continue  After 2 weeks of age:
                         observe   Consider PHARMACOLOGICAL Mx
                                   (First-line: Ibuprofen IV/oral)
                                          │
                                    Response to 1st course?
                                    ┌──────┴──────┐
                                   YES            NO
                                    │              │
                               Echo, observe   2nd course same drug
                                              OR switch drug
                                                    │
                                            Response to 2nd course?
                                            ┌──────┴──────┐
                                           YES            NO
                                            │              │
                                       Observe       Consider:
                                                   - Transcatheter closure
                                                     (if ≥700g, eligible)
                                                   - Surgical ligation
                                                     (last resort)

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SECTION 13: CONSERVATIVE MANAGEMENT

Principles

1. Fluid Management

• Day 1: 60-80 mL/kg/day
• Day 2-3: 80-100 mL/kg/day
• Day 4 onward: 120-150 mL/kg/day (advancing toward full feeds)

2. Ventilator Optimization

• Increase PEEP by 1-2 cmH2O above usual → increases intra-alveolar pressure → compresses pulmonary capillaries → reduces pulmonary blood flow → reduces L-R shunting
• Target: SpO2 91-95% (avoid hyperoxia which increases metabolic demand; avoid hypoxia which opposes ductal closure)
• If on CPAP: increase CPAP by 1 cmH2O
• If on HFO: increase MAP by 1-2 cmH2O
• Permissive hypercapnia (PaCO2 45-55 mmHg) to allow lower tidal volumes

3. Diuretics

• Furosemide: 1 mg/kg IV/PO
• Use only when clear evidence of pulmonary edema on CXR or clinically
• Warning: Furosemide INCREASES PGE2 synthesis (prostaglandin E2 production in thick ascending limb of Henle is stimulated by furosemide) → may actually oppose ductal closure and be counterproductive if used routinely
• Cochrane: Furosemide for PDA during COX inhibitor therapy (Kitaoka 2024) - found no consistent benefit and potential harm
• Hydrochlorothiazide/spironolactone: Preferred for longer-term diuresis if needed (do not stimulate PGE2)
• Evidence strength for diuretics in PDA: WEAK - no RCT evidence of benefit for PDA closure

4. Feeding Strategy (Conservative Phase)

• Commence trophic feeds early (10-20 mL/kg/day) even during PDA management if hemodynamically stable
• Hold or reduce feeds only if: pulmonary hemorrhage, evidence of mesenteric ischemia (abdominal distension, bloody stools), or starting indomethacin (hold for 24h)
• During ibuprofen: feeds can generally be continued if no signs of gut ischemia
• During paracetamol: feeds can continue
• Reason not to routinely hold feeds: Starvation increases intestinal injury; trophic feeds maintain gut mucosal integrity

5. Hemoglobin Optimization

• Target Hb: 120-140 g/L (Hct 35-40%) in symptomatic PDA
• Anemia (Hb < 100 g/L) increases magnitude of L-R shunting by:
  • Reducing blood viscosity → less resistance to shunt flow
  • Increasing compensatory cardiac output → more blood available to shunt
• Transfuse if Hb falls and PDA is hemodynamically significant

6. Inotropes (for Low Systemic Cardiac Output)

• Dopamine 5-10 mcg/kg/min: increases SVR → may reduce L-R shunting
• Dobutamine: improves myocardial contractility (LV output is often high in PDA - so dobutamine is rarely needed unless post-ligation cardiac syndrome)
• Important: Inotropes treat the secondary hypotension; they do NOT close the PDA. Address the cause.

When Conservative Management Alone is Appropriate

• GA > 28 weeks with no clinical signs → observe
• Any infant with PDA not meeting hsPDA criteria → expectant
• Any infant where drug risks outweigh benefits (severe AKI, severe thrombocytopenia, NEC)
• Any infant <2 weeks of age with hsPDA who is otherwise stable
• As first-line for all infants with hsPDA (2025 AAP recommendation)

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SECTION 14: MEDICAL TREATMENT

Indications for Pharmacological Treatment

1. Pulmonary hemorrhage clearly attributable to PDA (urgent)
2. Persistent hsPDA after ≥2 weeks of optimal conservative management
3. Hemodynamic instability clearly driven by PDA and not responding to conservative measures
4. Infant unable to wean from high-frequency/high-pressure ventilation due to PDA

Absolute Contraindications to All COX Inhibitors (Indomethacin/Ibuprofen)

Contraindications to Paracetamol

• Severe hepatic insufficiency (rare in neonates but possible)
• Known G6PD deficiency (use with caution - not absolute)
• Monitor liver enzymes if prolonged courses

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SECTION 15: DRUG COMPARISON - COMPLETE

Mechanism of Action

Detailed Drug Comparison Table

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INDOMETHACIN

• Mechanism: Prostaglandins (PGE2, PGI2) normally maintain afferent arteriolar dilation in the kidney. COX inhibition → prostaglandin synthesis blocked → afferent arteriolar vasoconstriction → reduced GFR → oliguria
• Especially pronounced in preterm infants who are volume-depleted or hypotensive
• Clinical: oliguria (<0.6 mL/kg/hr), rising creatinine
• Management: Ensure normovolemia; hold dose if creatinine rises >50% or oliguria; may need to switch to furosemide carefully
• Reversibility: Usually reversible within 24-48h of stopping drug

• Mechanism: COX-1 inhibition reduces cytoprotective PGE2 in intestinal mucosa → reduced mucosal blood flow via vasoconstriction → increased NEC susceptibility
• Also reduces mesenteric blood flow velocity acutely
• This is why feeds are held during indomethacin courses
• Evidence: Indomethacin vs ibuprofen meta-analysis: ibuprofen has significantly lower NEC risk (RR ~0.68)

• Mechanism: Indomethacin constricts cerebral vessels directly (non-prostaglandin mechanism involving adenosine and endothelin)
• This REDUCES cerebral blood flow by 20-30% acutely
• Dual significance:
  • Harmful: reduces oxygen delivery to vulnerable periventricular white matter
  • "Beneficial" (in prophylaxis): reduces cerebral blood flow fluctuations → lower IVH risk
• Clinical relevance: Administer as slow infusion (20-30 min), NOT bolus

• Mechanism: Direct vasoconstriction of splanchnic vessels + PGE2 loss
• SMA Doppler shows reduced end-diastolic velocity during indomethacin infusion
• Hold feeds for 24h before and during course

• Mechanism: COX-1 inhibition → reduced thromboxane A2 → impaired platelet aggregation (functional thrombocytopenia)
• Also: indomethacin may directly suppress megakaryopoiesis in preterm infants
• Platelet count may fall during treatment
• Significant clinical issue: check platelets before each course

• Hyponatremia (reduced free water excretion)
• Elevated bilirubin (minimal compared to ibuprofen)
• Reduced LV output transiently (from ductal closure + afterload increase)

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IBUPROFEN (IV and ORAL)

• Ibuprofen is slightly COX-2 preferential compared to indomethacin
• The renal medulla expresses more COX-2 (important for tubular function)
• However, the primary reason is pharmacokinetic: indomethacin achieves higher renal tissue concentrations and has a longer half-life in neonates (12-48h vs ibuprofen 10-20h)
• Ibuprofen is more highly protein-bound → less free drug reaches renal tissue
• Net result: oliguria is significantly less common with ibuprofen

• Ibuprofen is highly albumin-bound (>99%)
• It COMPETES with bilirubin for albumin binding sites
• → Displaces bilirubin from albumin → raises free unbound bilirubin → increases risk of kernicterus
• Clinical implication: If infant has significant jaundice (bilirubin > 10 mg/dL), prefer indomethacin or paracetamol over ibuprofen
• The newer ibuprofen lysine (IV) formulation has less bilirubin displacement than oral ibuprofen

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PARACETAMOL (ACETAMINOPHEN) - IV and ORAL

• 778 infants 23-28 weeks, prophylactic IV paracetamol vs placebo starting within 12 hours
• Paracetamol increased ductal closure on Day 7 (71.2% vs 52.2%, significant)
• BUT: No improvement in survival without morbidity (66.2% vs 63.6%, p=NS)
• Higher cholestasis in paracetamol group (6.4% vs 2.6%)
• Conclusion: Prophylactic paracetamol closes ducts but does not improve outcomes - confirming that closing the ductus per se does not matter for outcomes - the most powerful argument for expectant management.

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DRUG COMPARISON TABLE

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Drug Selection by Clinical Scenario

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SECTION 16: MANAGEMENT AFTER TREATMENT FAILURE

After Failure of First Course

• Define failure: PDA not closed on echo 24-48h after last dose AND clinically still significant
• Options:
  1. Second course of same drug (reasonable if partial response or good tolerance)
  2. Switch drug (if adverse effects from first drug: AKI from indomethacin → switch to paracetamol)
  3. Combination therapy: Ibuprofen + paracetamol (limited evidence; some benefit in refractory cases - exploits different mechanisms)
• When to repeat echo: 24-48h after completing first course; before starting second course; any clinical deterioration

After Failure of Two Courses

• Reassess: Is the PDA still hemodynamically significant? (Re-echo)
• Is the infant's overall status compatible with procedure?
• Options:
  1. Continued expectant management if stable (the baby may still close spontaneously even after failed medical treatment - this is more common than previously thought)
  2. Transcatheter (catheter) closure if weight ≥700g
  3. Surgical ligation (last resort)

When to Repeat Echocardiography

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SECTION 17: CATHETER CLOSURE AND SURGICAL LIGATION

Transcatheter Device Closure

• Piccolo Occluder (Abbott) - FDA-approved for infants ≥700g since 2019
• Muscular VSD occluder (off-label use)
• ADO II, Amplatzer Ductal Occluder (various sizes)

• Weight ≥700g (Piccolo Occluder FDA approval)
• Failed 2 courses of medical therapy with persistent hsPDA
• Medical therapy contraindicated
• Hemodynamically unstable, unable to wean ventilator

• Weight <700g (technical difficulty)
• Coexisting pulmonary hypertension (relative)
• Anatomy unsuitable (very tortuous or short ductus)
• Active sepsis

• Device embolization (rare)
• Left pulmonary artery stenosis (device protrusion)
• Femoral access complications (hematoma, arterial spasm)
• Residual shunt

Surgical Ligation

• All medical therapy failed or contraindicated
• Transcatheter closure not possible (weight <700g, anatomical issues)
• Pulmonary hemorrhage uncontrolled

• Recurrent laryngeal nerve injury (left-sided → hoarseness, aspiration)
• Chylothorax (thoracic duct injury)
• Pneumothorax
• Bleeding
• Post-ligation cardiac syndrome (PLCS)

Post-Ligation Cardiac Syndrome (PLCS)

• Hypotension developing 6-12h post-ligation
• Desaturation, increased ventilator requirements
• Acidosis
• Low LV output on echo

• Anticipate it in ALL infants after ligation
• Milrinone: 0.1-0.3 mcg/kg/min (reduces afterload + improves inotropy)
• Dobutamine: 5-10 mcg/kg/min (positive inotrope)
• Volume: cautious - the LV is volume-sensitive
• Hydrocortisone: if catecholamine-resistant hypotension (adrenal insufficiency component)
• Pre-operative milrinone (starting before ligation): some centers use prophylactic milrinone 0.1 mcg/kg/min for 24h post-op

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SECTION 18: VENTILATOR MANAGEMENT IN PDA

Principles

1. PEEP is your best friend in PDA management
   • Increase PEEP by 1-2 cmH2O above baseline
   • Physiological rationale: Higher alveolar pressure → compresses pulmonary capillaries → increases PVR → reduces L-R shunting
2. Target SpO2 91-95% (not 97-100%)
   • Hyperoxia: increases metabolic demand, promotes ductal constriction (beneficial) but at cost of oxygen toxicity
   • Aim for adequate oxygenation without excess
3. Permissive hypercapnia (PaCO2 45-60 mmHg)
   • Allows lower tidal volumes → less barotrauma
   • CO2 also has pulmonary vasoconstrictive effect (mild PVR increase → may reduce shunt)
4. Avoid excessive tidal volumes (target 4-5 mL/kg)
   • Pulmonary over-distension worsens edema and increases lung injury
5. High-Frequency Oscillatory Ventilation (HFOV):
   • Use when conventional ventilation failing due to pulmonary edema from PDA
   • High mean airway pressure (MAP) in HFO is particularly effective at reducing pulmonary blood flow
6. In pulmonary hemorrhage from PDA:
   • Immediately increase PEEP to 6-8 cmH2O
   • Suction blood gently but don't overdo suction (re-opens capillaries)
   • Give surfactant (blood inactivates surfactant)
   • Start indomethacin/ibuprofen urgently if not contraindicated

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SECTION 19: SPECIAL SITUATIONS

PDA in ELBW Infants (<750g or <28 weeks)

• Spontaneous closure is less likely but still occurs
• Drug efficacy is lower in ELBW infants
• Risk of drug toxicity is higher
• Current recommendation (AAP 2025): Expectant management as first-line even in ELBW
• If treatment needed: Paracetamol is often preferred (less toxicity profile)
• Transcatheter closure increasingly used if ≥700g and failed medical therapy
• Surgical ligation very high risk in infants <750g - significant mortality and PLCS

PDA with Severe IVH (Grade 3-4)

• Indomethacin traditionally used for IVH prophylaxis (reduces cerebral blood flow fluctuation)
• However: in infants who ALREADY have Grade 3-4 IVH, indomethacin → further cerebral blood flow reduction → risk of extending hemorrhage into white matter
• If hsPDA present with Grade 3-4 IVH: Paracetamol or ibuprofen (less cerebral vasoconstriction) preferred over indomethacin
• Conservative management strongly preferred if clinically stable
• Avoid sudden large fluid boluses (worsen IVH by increasing cerebral venous pressure)

PDA with NEC

• Both indomethacin and ibuprofen are absolutely contraindicated in active NEC (Bell stage ≥IIA)
• Paracetamol: safer option if PDA treatment truly necessary, but still use with caution
• If PDA is contributing to gut ischemia: consider urgent surgical ligation or transcatheter closure (counterintuitive but closing the ductal steal may actually be beneficial for gut perfusion)
• Prioritize NEC management; PDA treatment can wait unless pulmonary hemorrhage

PDA with Sepsis

• Sepsis increases PGE2 production → worsens PDA patency
• Sepsis also causes myocardial depression → reduces ability to compensate for shunt
• Treat sepsis first: antibiotics + supportive care
• Ibuprofen has mild anti-inflammatory properties - some benefit in sepsis context
• Indomethacin: may compromise renal function which is already stressed in sepsis
• Conservative management preferred until sepsis resolved; then reassess PDA

PDA with AKI

• If AKI present (creatinine >1.5 mg/dL or oliguria):
  • Contraindicated: Indomethacin and ibuprofen
  • Preferred: Paracetamol IV (no renal COX effect)
  • Conservative management with careful fluid balance
  • Monitoring: Creatinine q12-24h; urine output hourly

PDA with Pulmonary Hemorrhage

• Emergency: This can be rapidly fatal
• Immediate actions:
  1. Increase PEEP to 6-8 cmH2O (reduces capillary leak)
  2. Suction ETT carefully (assess if frank blood)
  3. Surfactant (400 mg/kg): blood inactivates surfactant
  4. Start indomethacin IV NOW if not contraindicated (fastest acting, most powerful)
  5. Blood transfusion if significant blood loss
  6. Consider FFP/platelets if coagulopathy
• If indomethacin contraindicated: ibuprofen IV or emergency surgical ligation

PDA with Severe BPD

• Infants with established BPD often have persistent or recurrent PDA
• They also have pulmonary hypertension which complicates PDA physiology
• In severe BPD: PDA may be bidirectional or even R→L
• In R→L PDA: DO NOT close - it acts as a safety valve for the RV
• Assess carefully with echo: direction of shunting, RV pressure
• If truly L→R with hemodynamic significance: medical treatment may help reduce pulmonary flooding

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SECTION 20: LANDMARK TRIALS

1. PDA-TOLERATE Trial (Clyman et al., Pediatrics, 2019)

• No difference in: death, BPD, NEC, IVH
• Higher rate of rescue treatment in conservative group (expected)
• Established feasibility of conservative management
• Impact: Shifted thinking from "treat all hsPDA" to "watchful waiting is safe"

2. BeNeDuctus Trial (Hundscheid et al., NEJM, December 2022, published March 2023)

• Primary outcome: 46.3% expectant vs. 63.5% ibuprofen (expectant NON-INFERIOR by large margin - actually SUPERIOR numerically)
• BPD: 33.3% expectant vs. 50.9% ibuprofen (significantly lower with expectant!)
• NEC: Similar (17.6% vs 15.3%)
• Death: 14.0% vs 18.2% (not statistically significant but trend favoring expectant) Impact: One of the most important recent trials. Established that early ibuprofen is NOT beneficial and may be harmful. Drove the shift to expectant management as standard of care.

3. Baby-OSCAR Trial (Gupta et al., NEJM, January 2024)

• Primary outcome: 69.2% ibuprofen vs. 63.5% placebo (p=0.10) - NO benefit from early ibuprofen
• Mortality: 13.6% ibuprofen vs. 10.3% placebo (not significant, but trend to harm) Impact: The largest RCT to date. Confirmed BeNeDuctus findings. Early ibuprofen for large PDA in extremely preterm infants does NOT improve outcomes.

4. PDA Randomized Clinical Trial (Laughon et al., JAMA, February 2026)

• Primary outcome: 80.9% expectant vs. 79.6% active treatment (p=0.73) - No difference
• MORTALITY: 4.1% expectant vs. 9.6% active treatment (p=0.01) - SIGNIFICANTLY HIGHER with treatment
• Deaths from infection: 0.8% expectant vs. 3.8% active treatment Stopped early for futility AND safety Impact: The strongest evidence yet that active treatment is not just ineffective but potentially harmful. Practice-changing. Virtually eliminates justification for early routine active treatment of PDA.

5. Cochrane: Early vs. Expectant Management (Mitra et al., June 2025)

• Death or moderate-severe BPD: Higher with active treatment (56.2% vs 50.8%, RR 1.10, p=0.02)
• Mortality: Higher with active treatment (14.3% vs 11.2%, RR 1.27, p=0.04) Impact: Definitive synthesis confirming expectant management as standard of care.

6. Cochrane: Paracetamol for PDA (Jasani et al., December 2022)

7. Prophylactic Acetaminophen RCT (Rozé et al., JAMA Pediatrics, April 2026)

• Ductal closure Day 7: 71.2% vs 52.2% (significant - paracetamol closes ducts)
• Survival without morbidity: 66.2% vs 63.6% (NOT significant)
• Cholestasis: 6.4% vs 2.6% (significantly higher with paracetamol) Profound implication: Paracetamol closes the ductus effectively, but this does not translate into better outcomes. Confirms that the act of closing the ductus does not in itself benefit the preterm infant.

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SECTION 21: CURRENT GUIDELINE RECOMMENDATIONS

AAP Clinical Report 2025 (Ambalavanan, Aucott, Salavitabar, Levy)

European Consensus Guidelines on RDS Management (Updated Autumn 2025)

• Align with AAP: expectant management preferred
• Ibuprofen (IV or oral) preferred over indomethacin due to lower side effect profile
• Paracetamol acceptable alternative
• No recommendation for routine prophylaxis

Canadian Paediatric Society (CPS) Position

• CPS aligns with trend toward conservative management
• Selective treatment for symptomatic hsPDA in infants who fail conservative management
• Same drug hierarchy as AAP: ibuprofen preferred

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SECTION 22: ONE-PAGE NICU MANAGEMENT ALGORITHM

╔══════════════════════════════════════════════════════════════╗
║        PDA MANAGEMENT IN PRETERM NEONATES - NICU PROTOCOL   ║
║                    (Based on 2025-2026 Evidence)             ║
╠══════════════════════════════════════════════════════════════╣
║  STEP 1: ASSESS (All preterm <32 weeks)                      ║
║  • Daily clinical exam: pulses, precordium, murmur, BP, UO   ║
║  • Echo within 48-72h for all <28 weeks                      ║
║  • BNP/NT-proBNP if echo not immediately available           ║
╠══════════════════════════════════════════════════════════════╣
║  STEP 2: CATEGORIZE                                          ║
║  Small PDA (not hsPDA): OBSERVE + serial clinical assessment ║
║  hsPDA (echo + clinical): CONSERVATIVE MANAGEMENT FIRST     ║
╠══════════════════════════════════════════════════════════════╣
║  STEP 3: CONSERVATIVE MANAGEMENT (ALL hsPDA - first 2 weeks) ║
║  ✓ Fluid: 60-80 mL/kg/d Day1 → titrate up gently            ║
║  ✓ PEEP: Increase by 1-2 cmH₂O from baseline                ║
║  ✓ O₂: Target SpO₂ 91-95% (avoid hyperoxia)                 ║
║  ✓ Hb: Transfuse if <100 g/L with significant PDA            ║
║  ✓ Feeds: Trophic feeds early (hold only for Indo treatment) ║
║  ✓ Diuretics: Only for pulmonary edema (avoid furosemide)    ║
║  ✓ EXCLUDE ductal-dependent CHD before any treatment        ║
╠══════════════════════════════════════════════════════════════╣
║  STEP 4: RE-ASSESS AT 2 WEEKS                                ║
║  Still hsPDA? Consider pharmacological treatment:            ║
║  ┌─────────────────────────────────────────────────────┐     ║
║  │ FIRST LINE: IBUPROFEN 10→5→5 mg/kg/day × 3 days    │     ║
║  │ (unless: jaundice, AKI, thrombocytopenia, NEC)      │     ║
║  │ ALT: PARACETAMOL 15mg/kg IV q6h × 3-7 days          │     ║
║  │ (if: AKI, thrombocytopenia, jaundice, NEC concern)  │     ║
║  │ INDOMETHACIN: Reserve for pulmonary hemorrhage       │     ║
║  └─────────────────────────────────────────────────────┘     ║
╠══════════════════════════════════════════════════════════════╣
║  STEP 5: AFTER 1st COURSE FAILURE (echo at 24-48h)          ║
║  Option A: 2nd course same drug (if tolerated)               ║
║  Option B: Switch drug (Ibuprofen → Paracetamol if toxicity) ║
║  Option C: Combination (limited evidence)                    ║
╠══════════════════════════════════════════════════════════════╣
║  STEP 6: AFTER 2nd COURSE FAILURE                           ║
║  Is PDA still truly hemodynamically significant? (Re-echo)   ║
║  If yes + ≥700g: TRANSCATHETER CLOSURE (Piccolo Occluder)    ║
║  If <700g or failed transcatheter: SURGICAL LIGATION         ║
║  Post-ligation: anticipate PLCS → Milrinone prophylaxis      ║
╠══════════════════════════════════════════════════════════════╣
║  EMERGENCY: PULMONARY HEMORRHAGE                             ║
║  1. PEEP ↑ to 6-8 cmH₂O IMMEDIATELY                         ║
║  2. Surfactant 200-400 mg/kg                                 ║
║  3. Indomethacin IV NOW (if no AKI/NEC/thrombocytopenia)    ║
║  4. Blood transfusion + FFP if coagulopathy                  ║
╚══════════════════════════════════════════════════════════════╝

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SECTION 23: FREQUENTLY ASKED VIVA QUESTIONS (DM/DrNB)

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SECTION 24: BEDSIDE PEARLS (CONSULTANT EXPECTATIONS)

1. "The baby who cannot be weaned from the ventilator after surfactant" - always think PDA. Echo within 24 hours.
2. "Wide pulse pressure is more reliable than a murmur" - murmur is absent in up to 40% of significant PDAs in ELBW infants. Feel the pulses.
3. "PEEP is your best non-pharmacological PDA therapy" - 1-2 cmH2O increase immediately reduces pulmonary blood flow.
4. "Don't close the duct if you haven't excluded ductal-dependent CHD" - this can kill the baby. Always get an echo before treatment.
5. "A PDA that closes with treatment but re-opens within 2 weeks is common" - ~25-35% re-opening rate. The ductus is developmentally immature; it will try to open again.
6. "Ibuprofen displaces bilirubin - check the bilirubin first" - if total bilirubin >8 mg/dL in a tiny preterm, consider paracetamol instead.
7. "Furosemide makes the PDA worse" - stimulates PGE2. Use spironolactone/hydrochlorothiazide if prolonged diuresis needed.
8. "Spontaneous closure rate is your ally" - even in 24-week infants, the ductus may close. Give it 2 weeks before reaching for drugs.
9. "Post-ligation cardiac syndrome is a certainty, not a possibility" - order milrinone infusion before the baby returns from theatre.
10. "BNP/NT-proBNP is for triage, echo is for diagnosis" - never make treatment decisions based on BNP alone.
11. "The 2026 JAMA trial stopped early because active treatment killed more babies" - this is the most powerful statement in modern PDA management. Internalize it.
12. "Combination ibuprofen + paracetamol exploits two different mechanisms" - ibuprofen blocks PGE2 synthesis; paracetamol blocks PGE2 synthesis at a different enzymatic step. Some benefit in refractory cases, though evidence is limited.

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SECTION 25: COMMON MISTAKES BY JUNIOR RESIDENTS

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SECTION 26: MNEMONICS SUMMARY

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SECTION 27: 30 HIGH-YIELD MCQs WITH EXPLANATIONS

• A) Start ibuprofen immediately
• B) Increase PEEP by 1-2 cmH2O and restrict fluids
• C) Surgical ligation
• D) Start indomethacin prophylaxis

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• A) Indomethacin increases cerebral blood flow
• B) Indomethacin has no effect on cerebral blood flow
• C) Indomethacin reduces cerebral blood flow by ~20-30%
• D) Indomethacin reduces IVH by increasing cerebral blood flow

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• A) Indomethacin causes more bilirubin displacement than ibuprofen
• B) Ibuprofen displaces bilirubin from albumin → risk of kernicterus
• C) Paracetamol increases bilirubin production
• D) Bilirubin level is normal for this age

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• A) Indomethacin vs ibuprofen in <28-week infants
• B) Early ibuprofen vs expectant management in infants <28 weeks with echo-confirmed PDA
• C) Prophylactic paracetamol vs placebo in 23-28 week infants
• D) Surgical ligation vs medical therapy

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• A) Surgical ligation introduces infection
• B) Sudden increase in LV afterload after removal of low-resistance ductal runoff
• C) Ligation causes acute aortic stenosis
• D) Anesthesia suppresses myocardial function

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• A) Furosemide increases pulmonary blood flow
• B) Furosemide stimulates PGE2 synthesis in the thick ascending limb of Henle
• C) Furosemide causes hyperkalemia
• D) Furosemide reduces surfactant production

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• A) Indomethacin IV
• B) Ibuprofen oral
• C) Paracetamol IV
• D) Emergency surgical ligation

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• A) LA:Ao ratio
• B) LV output
• C) Superior vena cava (SVC) flow
• D) Ductal diameter

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• A) Larger PDAs have more smooth muscle
• B) Paracetamol is a conditional COX inhibitor that is overwhelmed when PGE2 production is high
• C) Larger PDAs do not express COX enzymes
• D) Paracetamol is eliminated faster in infants with larger PDAs

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• A) Ibuprofen showed remarkable efficacy in closing PDAs
• B) Expectant management group had higher BPD
• C) Active treatment group had significantly higher mortality (9.6% vs 4.1%)
• D) No recruitment targets were met

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• A) Falling circulating prostaglandin E2
• B) Rising arterial PaO2 activating voltage-gated K+ channels
• C) Mechanical compression from inflating lungs
• D) Increased circulating adenosine

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• A) Indomethacin
• B) Paracetamol
• C) Either, as bilirubin displacement is same for all NSAIDs
• D) Neither - only surgical ligation is safe

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• A) Indomethacin does not close the ductus
• B) Multiple meta-analyses and the AAP 2025 report confirm no benefit on mortality, BPD, or neurodevelopment
• C) Indomethacin is too expensive
• D) Oral indomethacin is preferred

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• A) Start indomethacin IV
• B) Give packed red blood cells
• C) Increase PEEP to 6-8 cmH2O
• D) Perform emergency surgical ligation

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• A) Start ibuprofen immediately
• B) Conservative management with serial echo in 48-72 hours
• C) Immediate surgical ligation
• D) Indomethacin prophylaxis

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• A) 500g
• B) 700g
• C) 1000g
• D) 1500g

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• A) Oral paracetamol
• B) IV paracetamol
• C) IV indomethacin
• D) IV ibuprofen

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• A) Oral ibuprofen has equivalent closure rates to IV ibuprofen
• B) IV ibuprofen is associated with more severe renal toxicity than oral
• C) Oral ibuprofen is significantly cheaper than IV ibuprofen
• D) Oral ibuprofen bioavailability may be variable in sick preterm infants

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• A) Cyclooxygenase-2 (COX-2)
• B) EP4 receptor
• C) Voltage-gated K+ channels (Kv channels) in ductal smooth muscle
• D) Phosphodiesterase-3 (PDE3)

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• A) Early indomethacin reduces IVH significantly
• B) Early ibuprofen (<72h) for large PDA does not reduce death or BPD
• C) Paracetamol is superior to ibuprofen for PDA closure
• D) Surgical ligation reduces hospital stay

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• A) Extremely rare (<5%) and should never be relied upon
• B) Occurs in approximately 35-40% by 44 weeks PMA even without treatment
• C) Universal within the first week of life
• D) Only occurs after antenatal steroid exposure

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• A) NPO for entire 3-day course
• B) NPO for first 24h only, then resume trophic feeds if no signs of gut ischemia
• C) Full enteral feeds can continue if the infant is hemodynamically stable
• D) Parenteral nutrition only for 7 days

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• A) Non-selective COX inhibitor, same as indomethacin
• B) Selective COX-2 inhibitor
• C) Inhibition of the peroxidase component of COX, working when arachidonic acid concentrations are low
• D) Direct inhibition of EP4 prostaglandin receptors

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• A) Third aortic arch (left)
• B) Fourth aortic arch (right)
• C) Sixth aortic arch (left)
• D) Second aortic arch

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• A) 0.5-0.8
• B) 0.8-1.2
• C) 1.5-2.0
• D) 2.0-2.5

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• A) Rising creatinine after first course of ibuprofen
• B) Failure of first course of ibuprofen
• C) Pulmonary hemorrhage
• D) LV output >500 mL/kg/min

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• A) Active treatment significantly reduced BPD
• B) Active treatment significantly reduced IVH
• C) Active treatment was associated with higher mortality (RR 1.27)
• D) No difference in any outcome

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• A) Pulmonary overcirculation
• B) Systemic hypoperfusion, particularly cerebral, and high risk of IVH
• C) Pulmonary hypertension
• D) Hypervolemia

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• A) Third course of indomethacin
• B) Start corticosteroids
• C) Transcatheter closure with Piccolo Occluder (infant ≥700g)
• D) Accept the PDA as part of natural history and discharge

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• A) PDA should always be treated surgically
• B) Indomethacin is superior to ibuprofen
• C) Active treatment of hsPDA in the first 2-3 weeks does not improve and may worsen outcomes compared to expectant management
• D) Prophylactic paracetamol should be given to all infants <28 weeks

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CONSULTANT-LEVEL SUMMARY

What Every Consultant Must Know in 2026

1. Default expectant management for all hsPDA in preterm infants for the first 2 weeks of life, with conservative supportive care (PEEP optimization, gentle fluid restriction, hematocrit maintenance).
2. The 2026 JAMA trial is the landmark event: Active treatment associated with 9.6% mortality vs 4.1% expectant (p=0.01). Combined with BeNeDuctus and Baby-OSCAR, this is now essentially incontrovertible.
3. The ductus is not the enemy: Most close spontaneously. The real question is: "Which 10-15% of PDAs truly need intervention?"
4. Pharmacological closure remains available for specific situations: pulmonary hemorrhage, refractory hemodynamic instability after 2 weeks, inability to wean ventilator.
5. Drug of choice when needed: Ibuprofen (IV or oral) is preferred per AAP 2025 and European guidelines due to lower NEC risk vs indomethacin. Paracetamol is the alternative when COX inhibitors are contraindicated.
6. Transcatheter closure (Piccolo Occluder ≥700g) has replaced surgical ligation as the preferred procedural option. Surgical ligation rate has fallen from 4.4% to 0.84%.
7. Post-ligation cardiac syndrome must be anticipated and milrinone ordered prophylactically for all infants undergoing ligation.
8. Prophylactic treatment is dead: Prophylactic indomethacin and prophylactic paracetamol (Rozé 2026) both close ducts effectively but neither improves outcomes - confirming that ductal closure per se is not the goal; the goal is better outcomes.

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TOP 20 EXAM POINTS FOR DM/DrNB NEONATOLOGY AND NEET SS

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• The Developing Human: Clinically Oriented Embryology (Moore & Persaud)
• Robbins & Cotran Pathologic Basis of Disease, 10th ed.
• Schwartz's Principles of Surgery, 11th ed.
• Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed.
• Katzung's Basic and Clinical Pharmacology, 16th ed.
• Barash Clinical Anesthesia, 9th ed.
• Harriet Lane Handbook, 23rd ed.
• AAP Clinical Report on PDA Management 2025 (Ambalavanan, Aucott, Salavitabar, Levy; PMID: 41476734)
• BeNeDuctus Trial (Hundscheid et al., NEJM 2023; PMID 36477458)
• Baby-OSCAR Trial (Gupta et al., NEJM 2024; PMID 38265644)
• PDA Randomized Clinical Trial (Laughon et al., JAMA 2026; PMID 41364689)
• Cochrane: Paracetamol for PDA (Jasani et al., 2022; PMID 36519620)
• Cochrane: Early vs expectant management (Mitra et al., June 2025; PMID 40548426)
• Meta-analysis: Active treatment vs expectant (Buvaneswarran et al., JAMA Pediatrics 2025; PMID 40423988)
• Prophylactic Acetaminophen RCT (Rozé et al., JAMA Pediatrics 2026; PMID 41697673)
• Cochrane: Fluid restriction for PDA (MacLellan et al., 2024; PMID 39692231)
• NW Neonatal Network PDA Guideline 2025
• European Consensus Guidelines on RDS Management (updated Autumn 2025)
• Cochrane: Ibuprofen for PDA (Ohlsson et al., 2020; PMID 32045960)

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