12 patients with inconsistent growth of twins were involved.The acoustic features were analyzed,inclu-ding 2D and Doppler images.The differential diagnosis was verified during follow-up exam in some patients.8 cases were diagnosed with sIUGR by ultrasonography,meanwhile 3 were diagnosed with TTTS.The rest 1 case could not be etiologically diagnosed due to the bad image conditions.We can differentiate the two diseases by evaluating the umbilical cord insertion,the amiotic fluid and the hemodynamics of the other twin.Ultrasonography is helpful in the differential diagnosis for TTTS and sIUGR.