Normal newborns can sometimes present with cyanosis within 5 minutes of birth, due to the fact that the ductus arteriosus and foramen ovale have not yet closed and still maintain a right-to-left shunt, the lungs are not yet fully dilated, and there is imperfect lung ventilation as well as poor perfusion of peripheral skin blood flow. What are the tests for cyanosis of the extremities in neonates? The diagnosis of typical cyanosis of the extremities is generally not difficult. Cyanosis of the extremities of both hands and/or feet, with a localized decrease in skin temperature and coolness, but the patient does not feel pain, numbness, aggravated by cold conditions, and alleviated but not completely disappeared by warm conditions, is cyanosis of the extremities. In order to identify the primary or secondary. In principle, first of all should be a comprehensive examination, detailed medical history, a comprehensive physical examination and a variety of auxiliary examination, such as the absence of a variety of secondary cyanosis may be caused by the limbs, can be considered as the primary limb cyanosis. Diagnosis of cyanosis of extremities The lesion often involves both hands, manifested as the ends of the limbs, persistent, uniform cyanosis can appear in the whole hand and wrist and even the back, cold, exposure to cold air can worsen the symptoms, but the warm environment often can not make it reduce or disappear, accompanied by finger swelling, stiffness, sweaty palms. No ulceration or gangrene formation is seen.