endstream endobj 335 0 obj <> endobj 336 0 obj <> endobj 337 0 obj <>stream Soft ultrasound markers were initially described as a screening method for trisomy 21 to improve the detection rate over that based on age-related risk alone. The incidence of SUA is 0.25%–1% of all singleton pregnancies and up to 4.6% of twin gestations. An SUA can be detected on cross section of the umbilical cord during a routine second-trimester ultrasound exam or using color-flow Doppler to examine the umbilical arteries in the pelvis at an even earlier gestational age ( Fig. Obstetric Ultrasound - A Comprehensive Guide, Early second-trimester individualized estimation of trisomy 18 risk by ultrasound. �n�*p��x}��q��4A�]��� (� �R2 Third-trimester ultrasound for the evaluation of growth and appearance of bowel among fetuses with isolated echogenic bowel is therefore recommended. 345 0 obj <>/Filter/FlateDecode/ID[<330F1E3EEAB41442AEDF592061F7E309>]/Index[334 26]/Info 333 0 R/Length 76/Prev 1001135/Root 335 0 R/Size 360/Type/XRef/W[1 3 1]>>stream An EIF is defined as a small (<6 mm) echogenic area in either cardiac ventricle that is as bright as surrounding bone and visualized in at least two separate planes ( Fig.
Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window), Click to share on Google+ (Opens in new window), on Ultrasound Markers for Aneuploidy in the Second Trimester, Serum and Ultrasound Based Screening Tests for Aneuploidy, Genetic Evaluation of Fetal Sonographic Abnormalities. The pathophysiology of this finding is presumably due to areas of ischemia resulting from redistribution of blood flow away from the gut. �;�p��f_/縓�T�rvv=��f��ܻW�����Y{�?�s/y^��j��A�H��0��� ҕg'y������ם̚or�F2~. The normal umbilical cord contains two arteries and one vein; single umbilical artery (SUA) is the result of atrophy or agenesis of one of the arteries. How Trisomy 18, Trisomy 13, & Down Syndrome are actually diagnosed When isolated, in a population previously screened for aneuploidy, CPCs should be considered a variant of normal, and no additional aneuploidy testing is indicated. At the time of delivery, pediatricians should be made aware of the antenatal finding of echogenic bowel and prenatal workup performed, so that appropriate neonatal evaluation may be pursued. Some of the markers that may be seen via ultrasound for the three trisomies are: Studies have shown that a single marker found on ultrasound is usually not a good indicator of a chromosomal condition (ref 5,6).
The finding of dilated loops of bowel in addition to echogenic bowel may increase this risk to as high as 17%. The American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM) recommend that cfDNA screening be offered to patients with a higher risk for common aneuploidies, although any patient who desires aneuploidy screening may elect to pursue cfDNA screening. 10.1 ). Without a history of exposure or other clinical risk factors, the chance of positive results for other congenital infections, such as varicella, herpes, parvovirus, or toxoplasmosis, is very low. To fully assess and classify UTD, additional ultrasound features to be evaluated include presence of calyceal dilation, parenchymal thickness and appearance, ureteral dilation, bladder abnormalities, and amniotic fluid volume. CPCs are present in 30%–50% of fetuses with trisomy 18 but in such cases are typically seen alongside multiple structural anomalies, including structural heart defects, clenched hands, talipes deformity of the feet, growth restriction, and polyhydramnios. In 2011, the introduction of cell-free DNA (cfDNA) techniques greatly improved the ability to screen for common aneuploidies. The pathogenesis of this finding is unclear. Fetal echocardiography and additional ultrasound imaging solely to serially follow an EIF are not recommended, and no postnatal follow-up is indicated. 10.5 ). These markers are soft markers and structural markers. Ultrasound Measurements for Down Syndrome, Risk For Abnormal Chromosomes Following A Normal Genetic Ultrasound Examination, Ultrasound's Down Syndrome Markers Often Unreliable. Second Trimester Ultrasound Markers for Trisomy 18 159 Chapter 8 Second trimester ultrasound markers for trisomy 18 8.1 Introduction In many developed countries, a second trimester ultrasound examination at 18 to 22 weeks’ gestation is recommended as part of routine prenatal care to identify major structural anomalies. 334 0 obj <> endobj As she proceeded with the ultrasound, she noted a few “soft markers” (Clenched Fists & Heart Issues) and highly recommend that we do an amniocentesis immediately. Level II ultrasounds are typically conducted by a perinatologist, fetal medicine specialist, or someone else who specializes in high-risk pregnancies and who is trained to look for the markers of chromosomal disorders. Soft markers are not structural abnormalities; rather, they are minor ultrasound findings identified in the midtrimester that may be a variant of normal but are noteworthy because they have been associated with an increased risk of fetal aneuploidy. Congenital infection also has been associated with isolated echogenic bowel. h�[o�:���[����8���ĥt{�t��s��!/�%�N��;c����*�'_J��b�#�B�c�ӈ��I� 9����G� L�(��I!Ag�� �BH��, ;3�}�._���J+�U�t`J�/.�~��@92�Â~p�Ⱦ�fd��9����"�$�yw��7T/������#��y�@�%��g2 �+��p�R�ܼ|e���v9Qˊ0J�{�б����fO�^O�g�ן����zQ�N�2����� �i����"��ϒ��1��U6W�h�,5��By����͏/�r0�IU�j�����"�kՃ�ƧԻ��y6i/gs�%�Z��^(Zb�E���B/��� This finding is often isolated, but an increased incidence of structural anomalies, particularly renal and cardiac anomalies, has been demonstrated in fetuses with echogenic bowel. EIFs may appear in either cardiac ventricle, although left-sided EIFs are more common, and are thought to represent microcalcifications of papillary muscles. The purpose of this chapter is to focus on the evaluation and management of isolated ultrasound soft markers diagnosed in the second trimester. In other words, if only one marker is found during a level 2 ultrasound, the odds are very high that the baby is healthy. 10.4 ). The presence or absence of specific soft markers has been used to modify the probability of trisomy 21, and secondarily that of trisomy 18, using positive and negative likelihood ratios (LRs). (렉P��D`�b�Ȅ \��vt4`@D�8:$:::�H��L@UF �����` 0!�� Primary gastrointestinal pathology such as bowel obstruction, atresia, meconium peritonitis, and perforation also may cause an echogenic appearance of the fetal bowel, usually in association with other findings.
EIFs do not represent a structural or functional cardiac abnormality, and they have not been associated with cardiac malformations in the fetus or newborn.