Background: Modified Blalock-Taussig shunt (MBTS) is a common palliative procedure for congenital heart defect to connect the systemic to the pulmonary circulation via a synthetic shunt from a subclavian artery to a pulmonary artery. However, certain postoperative complications do exist, such as blockage. Early identification of modifiable risk factors is important to prompt early intervention for better outcomes. Material: This article is a descriptive narrative retrospective study. We gather data from the Cipto Mangunkusumo Hospital Cardiovascular Center medical report of 8 patients having undergone reoperation post-MBTS surgery as their first operation between January 2018 and October 2020. Data were analyzed using SPSS version 20 for Windows. Results: The patient’s age ranged from 3 months to 30 years old. Seven of them suffered from shunt occlusion complications, while the other suffered from the bleeding problem. The laboratory results showed that preoperative hemoglobin (18.9±4.1 g/dL vs. 16.90 (10.80-19.20) g/dL), hematocrit (58.8±12.40% vs. 42.9±14.30%), platelet counts (284.487±147.003 vs. 210.625±104.688) 103/uL, and oxygen saturation (86.00 (75.00-89.00) vs. 70.00±17.00) levels were higher than the pre-reoperative. The coagulation markers showed that PT value has increasing trend (1.10 (0.90-2.30) vs. 1.30±0.20) while aPTT (5.90 (2.90-6.30) vs. 2.30 (1.60-5.30)) seconds and activated clotting time (ACT) (205.00±86.00 vs. 165.00 (114.00-255.00)) showed the opposite. Conclusion: MBTS remains the first-choice bridging palliation surgery to increase the pulmonary blood flow in congenital heart defects. The cause of shunt failure remains inconclusive in this study. Other studies suggest that graft material choice, S/PA ratio, S/W ratio, operative approach, thrombus formation, and aPTT value contribute to shunt failure, thus needing a reoperation. © 2021, Sanglah General Hospital. All rights reserved.