Strength and limitation
The limitations of the current study are that the results were examined based on subjective evaluation of both SMI and pathology, although pathologic evaluations are usually performed based on subjective evaluations. While it is considered that a certain degree of consensus is achieved between pathologists regarding the pathological findings, there is no established consensus for diagnosing using SMI even though few inter-observer errors have been established. Previous studies have quantitatively evaluated placental Doppler intensity, such as vascular index and flow index 4. Conventional color Doppler detects both villous blood flow and gross intervillous blood flow . However, we believe that the strength of placental pathological evaluation using SMI is that the blood flow from the mother and fetus can be distinguished. The method of qualitative evaluation based on the pathology, instead of quantitative evaluation, would be more exact and useful in the perinatal management of placental abnormalities.