SonographicAssessment of the Types of Yolk Sac Abnormalities in First Trimester Missed Miscarriage

Abstract

Early pregnancy is now defined as the first 12 weeks of pregnancy which was previously known as the first trimester of pregnancy.Miscarriage is the most common complication of pregnancy; it has been estimated that the overall miscarriage rate is around 50%. Even though the majority of these losses occur before a missed menstrual period, bleeding complicates about 20%-25% of clinically detected pregnancies and 12–15% are lost. Behind every normal human embryo stands the combined contribution of the YS, the amnions, and the placenta. The YS is a round fluid structure seen within the gestational sac. The presence of a YS within the gestational sac is diagnostic of an intrauterine pregnancy, but does not confirm viability. On TVS, the YS is typically seen by approximately 5.5 weeks of gestation and/or when the mean gestational sac diameter is ≥8 mm. Assessment of the YS should be part of a complete first-trimester sonographic examination. An abnormality in the sonographic appearance ofYS can predict subsequent embryonic death or abnormalities. Therefore, accurate recognition of the normal and abnormal sonographic findings related to the YS can be used to anticipate the course of pregnancy The advent of high-resolutionultrasound imaging has enabled the anatomy and physiologyof the human fetal adnexae to be studied in vivofromas early as the third week postimplantationforward. Specially, TVS, with its ability to provide accurate invivoimages of the early gestational sac, has also providednecessary evidence to the epidemiology and pathophysiology of the failure of pregnancy at an early age. Ultrasound has not only changedthe medical approach to spontaneous miscarriage butalso the patient’s perception of normal and abnormalfetal development in utero. Theaims of our study are to measure and describe the patterns of YS abnormalities and to identify the relation between these abnormalities and other early embryonic morphologic abnormalities detected by TVS in cases of first trimester missed miscarriage. The study was carried out on 204 women (ages, 18-45 years) who had missed miscarriage with gestational age ≤11 weeks, diagnosed by TVS. Missed miscarriage pregnant females were recruited from the ultrasound and fetal care unit, Demerdash Hospital, Ain Shams University. TVS was done for missed miscarriage patients.Ultrasonographic findings of YS classified according to Kurjac et al., (2008)into:diameter, shape, and ultrasonographic appearance Early embryonic morphological findings of conceptuses were classified according to Poland’s classification in toGD1, GD2, GD3 and GD4.Ultrasonographic findings of embryos and YS of those 204 pregnancies were correlated. We found a significant relation between each of the YS diameter, shape and appearance with embryonic morphology in missed miscarriage cases. The relation between YS diameter and embryonic morphology whennormal YS was linked more frequently tonormal morphologic embryos (48.72%). Findings ofabsent YS were seen in 45.10% of anembryonic gestations (GD1) and 0.00% of normal morphologic embryos. Likewise, findings oftoo small YS were seen more frequently in 38.89% of GD4 embryos and 37.04% of GD3. Too large YS wasassociated with GD4 (31.67%) and normal morphologic embryos (30.00%). As regards of the relation between embryonic morphology and