Retroperitoneal teratoma surgery 1 month review, if it is diagnosed that it is not cut cleanly, should be carried out as early as possible secondary surgery. Because teratoma has the possibility of malignant transformation, it is better to operate earlier. Retroperitoneal teratoma is a common tumor in infants and young children, there are no symptoms in the early stage, only when the development of the abdomen to feel the mass is detected. In most cases, retroperitoneal teratoma is benign and in a few cases, it is malignant. Clinically, retroperitoneal teratoma can be performed by abdominal ultrasound and color Doppler imaging to determine the tumor. Abdominal ultrasound can diagnose retroperitoneal teratoma by echogenicity, border, envelope, and distribution. Color Doppler can show the tumor through the color blood flow signal. If the Doppler visible venous blood flow spectrum, there is a possibility of malignant transformation, and it is recommended to follow the doctor’s advice to carry out a second operation to avoid delaying the condition.