Blighted ovum is;

Ans. is b, i.e. Avascular villiRef. Dutta Obs. 7/e, p 161; Fernando Arias 2/e, p 56According to the clinical and echographic findings, it is possible to separate early pregnancy losses into two groups:Blighted ova: Those early pregnancy losses in which foetal development is not observed with ultrasound (so that only a gestational sac is present with or without a yolk sac) and fetal tissue is absent on histologic examination of the products of conception.Early Fetal demise: Those early pregnancy losses in which fetal development is clearly observed by ultrasound and fetal tissue is found on the histologic examination.The difference between these two types of abortion is of fundamental importance. The lack of development of fetal structures defines a subset of abortions of genetic origin.In contrast, the early interruption of fetal life is a complex phenomenon with multiple etiologies. Therefore, the patients with blighted ova do not require extensive work up, whereas patients who have aborted cytogenetically normal fetuses need an extensive search for non genetic factors responsible for the pregnancy loss.