At present, the incidence of monochorionic twins in all pregnancies is around 3-5‰ worldwide.In 2019, the twin Committee of China Maternal and Child Health Association conducted statistics from 48 medical units all over the country, showing that there were 4,876 cases of monochorionic twins, accounting for 10.2‰ of all pregnancies.In addition to increased incidence of preterm delivery, miscarriage, and maternal complication, the unique placental vascular structure of monochorionic twins is associated with complex fetal complication such as twin-twin transfusion syndrome, selective intraurine growth restriction, twin anaemia-erythrocytosis sequence, twin reversed arterial perfusion sequence, one of twin with dysplasia, twins with single amniotic sac and conjunctions are common. At present, there is no unified standard for the diagnosis and treatment of these complicated twins, and various treatment methods have a great impact on the pregnancy outcome and fetal prognosis.Therefore, the standardized management of complex twins benefits diagnosis and treatment of complex twins and improves fetal prognosis.

Inclusion Criteria:

complex twin disease 18-45 years

Exclusion Criteria:

single pregnancy normal twin pregnancy