Background: The patent ductus arteriosus (PDA) is a vital fetal structure that connects the descending aorta and the main pulmonary artery. It typically closes spontaneously after birth, but sometimes ductal patency persists for weeks. The PDA's physiological impact and clinical significance depend on its size and patient's cardiovascular status.
Aim of the study: To evaluate the effect of platelet count on the spontaneous closure of ductus arteriosus in preterm infants. 
Methodology: This is a cross section study analyzed 50 preterm infants less than 34 weeks gestational age with patent ductus arteriosus, divided into two groups with open and closed PDAs. Variables such as platelet count, mean platelet volume, platelet mass index and functions were compared to identify which factors influencing spontaneous closure of ductus arteriosus.
Results: The study involved a total of fifty neonates with mean gestational ages 32.4±1.3 weeks, 1.27±0.14 birth weights, 52% males, and 72% born by CS. Over half of the PDA cases had respiratory distress, 18% had low birth weight, 14% were infants of diabetic mothers, and only 3 had intrauterine growth retardation. The mean hemoglobin level was 12.6±2.8 gm/dl, mean TLC was 10.2±3.9/dl, and mean platelet was 52.2±11.3/dl. Over half of the cases had positive CRP (56%). 26% of PDA cases had associated patent foramen oval, 24% had associated ASD, and 20% had associated VSD. After a week of follow-up, 42% had closed PDA, and 58% had closed PDA after a month. 37.9% of cases with opened PDA after 1 week of follow up had platelet transfusion compared to 52.4% of cases with closed PDA with non-statistically significant p value >0.05. About 64% of cases with opened PDA had received platelet transfusion during one-month follow-up of the study.
Conclusion: Closure of the patent ductus arteriosus in premature infants is not affected by the number of platelets.