Vasa previa or not? A special parachute type of placenta caused dispute in ultrasonography diagnosis: A case report.Hong Ling1, Wu Jiahan1.1 Department of Obstetrics and Gynecology, Ningbo Women and Children Hospital, Ningbo 315010, ChinaCorresponding AuthorWu JiahanNo. 339 Liuting Street, Haishu District, Ningbo, Zhejiang Province, China.Telephone number +86 13805840722  e-mail 3014078594@qq.comCo-authorHong LingNo. 339 Liuting Street, Haishu District, Ningbo, Zhejiang Province, China.Telephone number +86 13655742069  e-mail 409180445@qq.comshortened running title: Vasa previa or not? MRI for parachute placenta

[Abstract] Objective To explore the MRI assistance in diagnosing of vasa previa when inconclusive ultrasonography results come. Methods From January 2018 to December 2021, 12 patients with suspected vasa previa but inconclusive ultrasonography diagnoses at 23-25w or 31-33w were enrolled into the study group. 51 patients diagnosed by ultrasonography as mild ventriculomegaly with no vasa previa were enrolled into the control group. Both groups had taken MRI scanning during the 3rd trimester to check the existence of vasa previa. Placentas from both groups were checked to confirm the existences of vasa previa immediately at delivery, and postoperatively by pathology. Results In the 12 patients from the study group, MRI demonstrated vasa previa in 11 patients. The rest one was excluded of vasa previa by MRI. In all the 51 patients from the control group, MRI had excluded vasa previa. Pathology examination after delivery had confirmed these MRI diagnoses. Conclusion When inconclusive ultrasonography interpretations on vasa previa come, MRI may offer some assistance in diagnosis.