Calcified Yolk Sac Appearance: From Sonography to Embryoscopy.

During organogenesis, the yolk sac is the primary route of exchange between the mother and the embryo.[1] It forms at approximately 24 days of gestational age[2] and has nutritive, endocrine, metabolic, immunologic and hematopoietic functions.[1] Abnormalities of the yolk sac have been associated with malformations and poor pregnancy outcomes.[3]

We present a case of a 38-year-old female, G3P1, with a history of a prior cesarean, who presented with a second consecutive first-trimester missed abortion. After sonographic evaluation [Figure 1], a transcervical embryoscopy [Figures 2 and 3] was performed. The procedure allowed direct visualization of the products of conception, entrance in the gestational sac through the chorion and the amnion, and collection of direct biopsies avoiding contamination. A Carnegie stage 14 normal embryonic anatomy was recognized with clear enlarging upper limbs, lower limb buds, and head flexed over the body [Figure 3]. A round, echogenic, normal sized yolk sac was identified during sonography [Figure 1, arrow shows the yolk sac], compatible with a calcification process after a few days of embryonic death.[4] In embryoscopy, this structure corresponded to a pearly “golf ball”-like structure lying outside the embryo [Figure 2].

Figure 1

Appreciate the yolk sac (arrow) as a hyperechogenic round structure and the embryo inside the gestational sac

Figure 2

Detail of the hysteroscopic view of the calcified yolk sac (pearly structure) outside the gestational sac

Figure 3

Detail of the hysteroscopic view of Carnegie stage 14 normal embryo inside the gestational sac

A recent article documented the normal hysteroscopic appearance of the yolk sac.[5] To the best of our knowledge, the detailed hysteroscopic appearance of a calcified yolk sac has never been reported. With embryoscopy HAVING A crescent role in the evaluation of DEAD embryos, awareness of BOTH sonographic (presence, size, format, and echogenicity) and hysteroscopic appearance (presence, size, format, and color) of yolk sac and their correlation may be beneficial and help to clarify underestimated abnormalities in missed abortions.

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The authors certify that they have obtained all appropriate patient consent forms. In the form the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initial will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

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Nil.

Conflicts of interest

There are no conflicts of interest.