A large number of basic and clinical studies have been conducted worldwide on preterm infants with patent ductus arteriosus (PDA), but there is still much controversy regarding the clinical significance, evaluation, and treatment of PDA in preterm infants. The purpose of this article is to summarize relevant research evidence to guide the evaluation and treatment of persistent PDA in preterm infants early in life. Epidemiology and natural history In normal term infants, the ductus arteriosus tends to close functionally within 72 hours of birth. In preterm infants born at 30-37 weeks of gestational age, approximately 10% remain open on the fourth postnatal day; in preterm infants born at 25-28 weeks of gestational age, approximately 80% remain open. Approximately 73% of untreated neonates >28 weeks of gestational age close spontaneously; approximately 94% of neonates with a birth weight >1000 g close spontaneously; and approximately 93% of preterm infants without respiratory distress syndrome and 26-29 weeks of gestational age close spontaneously. While the ductus arteriosus remains open after birth, aortic blood flows into the pulmonary artery. During the first few days of life, pulmonary vascular resistance decreases, the proportion of aortic blood shunting into the pulmonary artery increases accordingly, and blood shunting from the body circulation exceeds the compensatory capacity of cardiac output, resulting in reduced perfusion of vital organs. Sustained PDA prolongs the duration of assisted ventilation, increases the risk of bronchopulmonary dysplasia, pulmonary hemorrhage, mortality from necrotizing small bowel colitis, renal impairment, intraventricular hemorrhage and cerebral palsy. Hemodynamic assessment The hemodynamic effects of left-to-right shunts in PDA can be confirmed by physical examination, echocardiography, or serum markers. In addition to the typical continuous systolic machine-like murmur at the left sternal border, affected neonates may have precordial pulsations, macroscopic peripheral pulsations, and vascular pulsations in the nail bed. However, none of these presentations are specific and cannot be correlated with echocardiographic findings. The presence of PDA is primarily confirmed by echocardiography, which also allows measurement of catheter width, assessment of flow direction and velocity, left ventricular volume and pressure load. echocardiographic findings of fractional flow and decreased after catheter closure. Laboratory studies have found that elevated BNP or troponin T at 48 hours of life may predict mortality or severe ventricular hemorrhage as well as neurodevelopmental prognosis. Hemodynamically significant PDA is associated with reduced local brain tissue oxygen saturation, increased oxygen uptake, and reduced abdominal arterial blood flow, which also suggests that persistent PDA may cause serious adverse outcomes. Is early treatment beneficial A large number of randomized controlled studies have confirmed that NSAIDs or surgical treatment of PDA is effective in closing the ductus arteriosus. Prophylactic treatment with indomethacin within 12 hours of birth reduced the incidence of intraventricular hemorrhage, early severe pulmonary hemorrhage, but did not improve long-term neurodevelopmental and respiratory prognosis, and the early neuroprotective effect of indomethacin use may not be dependent on arterial duct closure. Current evidence mostly supports that early (two weeks after birth), routine treatment to close the ductus arteriosus does not improve the long-term prognosis of preterm infants. Although surgical ligation can close the ductus arteriosus quickly and effectively, surgical treatment is commonly used for severe hemodynamic and respiratory abnormalities that also require intensive monitoring. Long-term complications of surgery include left vocal cord palsy, celiac disease, and diaphragmatic palsy, but the level of surgery varies by center, and the probability of complications is negatively correlated with the level of cardiac center maturation. Clinical research outlook Although early and routine treatment of PDA does not improve the long-term prognosis of the child, the absence of early intervention does not mean that the disease itself is completely ignored. First, clinical studies related to limiting pulmonary blood flow, increasing cardiac output, and reducing pulmonary edema are still needed. Second, early identification of children at high risk for PDA based on echocardiographic, serum biomarker, and hemodynamic monitoring findings allows for selective early intervention for these children, and a small number of very preterm infants may be in this high-risk group. Therefore, surgical treatment opportunities should be actively sought to increase survival rates and reduce long-term complications when there is foresight to determine that medical treatment is not effective.