Very Large Yolk Sac and Bicornuate Uterus in a Live Birth

Abstract

Pregnancies with a very large yolk sac are generally always associated with poor outcomes. Herein, we present a case in which a very large yolk sac (mean diameter, 8.1 mm) and a bicornuate uterus were shown on transvaginal sonography in the first trimester, but which resulted in a live birth. To our knowledge, this is the largest yolk sac among all cases accompanying live births which have been published in the literature. The unusual enlargement of the yolk sac may be secondary to the compensation effect for the poor blood supply in the medial wall of the bicornuate uterus for the conceptus. To predict the outcome of pregnancy, based on this case report, the quality of the yolk sac might be more important than its size.

Uterine structural anomalies and arthrogryposis—death of an urban legend

“…It is important to point out that there are several familial forms of uterine structural abnormalities as well as the inherited combination of uterine and urinary tract structural anomalies [Nykiforuk, 1938;Polishuk and Ron, 1974;Kurtz et al, 1980;Biedel et al, 1984;Stone et al, 2000;Cho et al, 2005;Uliana et al, 2008] in which fetal deformation might be expected to occur secondary to maternal uterine constraint. As well, there are syndromes and chromosomal anomalies in which uterine structural anomalies are known to occur [Shanks, 1956;Reece et al, 1982;Stone et al, 2000;Puvabanditsin et al, 2003;Ramirez and Lammer, 2004;Cho et al, 2005;Forzano et al, 2005;Mohan et al, 2006;Uliana et al, 2008]. Two of the 33 cases in this series have a history suggestive of a genetic form of uterine anomaly in mother.…”

The quality and size of yolk sac in early pregnancy loss

“…4 To our knowledge, this is the largest yolk sac associated with a live birth. 20 In this case, the placenta was implanted into the septum of a bicornuate uterus. The unusual growth of the yolk sac may be influenced by environmental factors.…”

“…The unusual growth of the yolk sac may be influenced by environmental factors. 20 To precisely diagnose pregnancy failure in an 'empty' gestational sac (without an embryo and a yolk sac), the discriminatory gestational date should be confirmed. 17 A significant difference between the size of the gestational sac in normal and abnormal pregnancies should appear after six weeks' gestation (8.2 vs 4.5 mm) due in part to the different vascularisation.…”

Prognostic Factors of Ultrasonography of Yolk Sac Size and Embryonic Heart Rate in First Trimester Pregnancy Outcome

“…Different studies have investigated the size, structure and function of the yolk sac [7] and [8]. The pregnancies with a yolk sac diameter >5 mm had a significantly higher risk of miscarriage.…”