First-trimester Findings Research Articles

Fused yolk sacs in a case of forked umbilical cord in monochorionic diamniotic twin pregnancy: sonoembryological implications

Forked cord (FC), which presents as a fused insertion of two umbilical cords into a monochorionic placenta, is a rare entity, especially in monochorionic diamniotic (MCDA) twin pregnancies. Herein, we describe a case of a MCDA pregnancy with FC, which showed characteristic findings on first-trimester ultrasound examination. A healthy 29-year-old nulliparous woman presented at 8 weeks of gestation following a positive result on pregnancy self-testing. Transvaginal ultrasound revealed two fetuses with active heartbeats and both had their own amniotic membrane, suggesting a MCDA pregnancy (Figure 1a). Noteworthy was that the two yolk sacs were completely fused (Figure 1b) and the connecting stalks, which are the site of the future umbilicus, were located in close proximity to one another (Figure 1c). On transabdominal ultrasound screening at 16 weeks of gestation (Figure 2a), FC was diagnosed but no other abnormalities were detected. The pregnancy course was uneventful and healthy female babies, weighing 2285 g and 2345 g, were born vaginally at 36 weeks. The umbilical and placental inspection revealed that each umbilical cord had two arteries and one vein, which fused near the placental surface, where the amniotic membranes divided the amniotic cavities (Figure 2b). Most cases of previously reported FC were observed in monochorionic monoamniotic (MCMA) twin pregnancies, which were frequently accompanied by an acardiac twin1, 2. Thomas et al. was the first to report an antenatally diagnosed case of FC in an otherwise uncomplicated MCDA pregnancy, in which FC was recognized at 30 weeks, and healthy infants (weighing 2460 g and 2490 g) were delivered at 35 weeks3. Frisch et al. reported a case of FC in a MCMA pregnancy diagnosed at 10 weeks, in which the twin pair (weighing 1169 g and 935 g) was delivered at 29 weeks because of abnormal fetal heart rate patterns4. In our case, which is the third report in the literature of liveborn twins with prenatal diagnosis of FC, the unique findings were the fused yolk sacs, with the amniotic membranes dividing the two fetuses as early as 8 weeks of gestation, in addition to the closely located connecting stalks. From an embryological viewpoint, the folding of the embryo and the expansion of the amniotic cavity, which bring the connecting stalk and yolk sac together to form the umbilical cord, occur after 9 weeks of gestation5. We postulate that our findings at 8 weeks of the fused yolk sacs and the closely located connecting stalks might be forecasting subsequent FC, even when the amniotic membranes dividing two embryos are visualized. As for the blood volume balance between the twins, we agree with the speculation of Thomas et al. and Frisch et al. that a fenestration between the two umbilical vein walls may have had a protective effect on the hemodynamic status of the twins3 and that FC itself in MCMA and MCDA pregnancies does not necessarily cause adverse perinatal outcome4. Our first-trimester findings provide new insights into sonoembryology, especially in relation to umbilical cord development from connecting stalks.

Detection of structural abnormalities in fetuses with normal karyotype at 11–13 weeks using the anatomic examination protocol of the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG)

Objective: To assess the performance of sonography in the detection of fetal nonchromosomal abnormalities using a standard anatomic examination protocol proposed by International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) at 11+0–13+6 weeks.Materials and methods: A prospective observational study was conducted between June 2013–May 2017 in singleton pregnancies attending for a routine scan at 11+0–13+6 weeks. All examinations were performed by maternal-fetal medicine specialists certified by the Fetal Medicine Foundation according to the anatomic examination protocol described in the ISUOG guidelines. First-trimester findings were compared to those of the anomaly scan at 20+0–23+6 weeks and the postnatal examination. The primary outcome was the detection rate of major structural abnormalities in fetuses with normal karyotype at 11+0–13+6 weeks.Results: After excluding 17 chromosomal abnormalities, major fetal structural defects were detected in 57 (1.7%) of the remaining 3361 cases. Of these, 27 (47.3%) were detected at 11+0–13+6 weeks, including all cases of acrania (4), exomphalos (4), megacystis (2) and body stalk anomaly (2). Furthermore, there was a first-trimester diagnosis in 36.4% (4/11) of major cardiac defects, 38% (6/16) of limb defects, and 100% (2/2) of facial clefts.Discussion: Targeted ultrasound examination may identify all the so called “always” detectable major abnormalities and a significant proportion of the “sometimes”, detectable at 11+0–13+6 weeks.

Non-visualization of choroid plexus of fourth ventricle as first-trimester predictor of posterior fossa anomalies and chromosomal defects.

To assess non-visualization of the choroid plexus of the fourth ventricle (CP-4V) as a simple, qualitative and reproducible first-trimester ultrasound feature of the posterior fossa for the prediction of central nervous system (CNS) anomalies and chromosomal defects. First-trimester three-dimensional ultrasound datasets of the fetal brain were obtained prospectively from 65 consecutive normal singletons and retrospectively from 27 fetuses identified as having an abnormal posterior fossa on first-trimester ultrasound examination, and randomly combined to form the final study group. The stored ultrasound volumes were analyzed offline by two accredited sonologists, who were not aware of the final diagnoses. The CP-4V was assessed by multiplanar navigation and classified as visible or non-visible in its normal position depending on whether or not the echogenic structure that separates the fourth ventricle from the cisterna magna was identified in both midsagittal and axial planes. Correlation with subsequent second-trimester ultrasound, fetal magnetic resonance imaging, or postmortem or postnatal findings was performed to determine the predictive value of the first-trimester findings. Among the 92 ultrasound datasets analyzed, 73 (79%) were acquired transabdominally and 19 (21%) transvaginally. The CP-4V was classified as visible in 64 cases and non-visible in 28 cases, with agreement between the two observers in both sagittal and axial planes in all but one case. Twelve of the 28 (43%) fetuses with non-visible CP-4V were subsequently diagnosed as having a CNS malformation (open spina bifida (n = 6), Dandy-Walker malformation (n = 2), Blake's pouch cyst (n = 2), cephalocele (n = 1) and megacisterna magna (n = 1)). In addition, 20 of these 28 (71%) fetuses had aneuploidy (trisomy 18 (n = 10), triploidy (n = 5), trisomy 13 (n = 3), Turner syndrome (n = 1) or trisomy 21 (n = 1)). There was only one false-positive case, in which the CP-4V was classified as absent in a normal fetus. Non-visualization of the CP-4V in the first trimester appears to be a strong marker of posterior fossa anomalies and chromosomal defects. Qualitative evaluation of this anatomic structure is simple, feasible and reproducible, and its routine assessment during the first-trimester scan may facilitate the early detection of CNS anomalies and associated fetal aneuploidy. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Placental implantation abnormalities: a modern approach.

Placental implantation abnormalities (PIAs) comprise a large group of disorders associated with significant maternal, fetal, and neonatal morbidity. Risk factors include prior uterine surgery/myometrial scarring and the presence of placenta previa with or without prior cesarean delivery. Newly identified risk factors include previous prelabor cesarean delivery and previous postpartum hemorrhage. PIAs contribute substantially to preterm birth with prematurity rates ranging from 38 to 82%. Diagnosis is typically made by ultrasound in the second or third trimester; transvaginal ultrasound and color Doppler are useful in evaluating for placental invasion, placental edge thickness, presence of fetal vessels, and cervical length. Suggestive MRI features include increased vascularity, dark T2 bands, uterine bulging, thin or indistinct myometrium, and loss of dark T2 interface. An important first-trimester finding is the implantation of the gestational sac into prior hysterotomy scar (cesarean scar pregnancy). Recommendations for delivery are universally preterm and based on expert opinion. Proposed management strategies are outlined depending on cervical length, distance between internal cervical os and placenta, and placental edge thickness. There has been a recent shift in focus to individualizing management in order to improve delivery timing and in some cases even decrease risks associated with prematurity. There is a need for larger prospective studies or randomized trials to show that individualizing care can improve outcomes.

What are the most common first-trimester ultrasound findings in cases of Turner syndrome?

Objectives: To identify the most common first-trimester ultrasound findings in Turner syndrome (TS). To evaluate which first-trimester findings can be best used to predict the likelihood of TS.Methods: This was a prospective study, based on singleton pregnancies. The referrals included 6210 patients. Scan protocol covered a review of the early fetal anatomy and markers of aneuploidy.Results: Study population comprised 5644 pregnancies: 5613 with a normal karyotype and 31 cases of TS. Statistically significant differences (p < 0.05) were found between euploidy and TS groups in terms of nuchal translucency (NT; 1.7 mm versus 8.8 mm) and fetal heart rate (FHR; 160 versus 171 beats per minute). None of the TS cases demonstrated absent markers of aneuploidy as opposed to 5133 (91.4%) cases of euploidy. NT and abnormal DV flow (aDV or revDV) were the most common markers found in combination in TS cases (n = 17; 54.8%). 27 (0.5%) cases of euploidy and 17 (54.8%) cases of TS revealed congenital heart defects. Fetal hydrops was observed in 14 cases of TS (43.8%) and in 5 of euploidy (0.1%). In backward regression model, NT > 3.5 mm and right dominant heart (RDH) augmented the risk of TS risk by 991 and 314 times, respectively.Conclusions: First-trimester sonography is a feasible method to identify the most characteristic features of TS fenotype. When the first-trimester pattern of TS is considered, a highly thickened NT, FHR above the 95th percentile, abnormal ductus venosus velocimetry, fetal hydrops, and RDH should be specifically searched for.

Sonographic detection of central nervous system defects in the first trimester of pregnancy.

The fetal central nervous system can already be examined in the first trimester of pregnancy. Acrania, alobar holoprosencephaly, cephaloceles, and spina bifida can confidently be diagnosed at that stage and should actively be looked for in every fetus undergoing first-trimester ultrasound. For some other conditions, such as vermian anomalies and agenesis of the corpus callosum, markers have been identified, but the diagnosis can only be confirmed in the second trimester of gestation. For these conditions, data on sensitivity and more importantly specificity and false positives are lacking, and one should therefore be aware not to falsely reassure or scare expecting parents based on first-trimester findings. This review summarizes the current knowledge of first-trimester neurosonography in the normal and abnormal fetus and gives an overview of which diseases can be diagnosed.

Early fetal anatomy screening: who, what, when and why?

This article reviews the potential benefits and downsides of early anatomy screening. There is increasing evidence that about 50% of severe fetal anomalies can be diagnosed prior to 14 weeks of gestation. 'Red flags' such as an increased nuchal or intracranial translucency, tricuspid valve regurgitation, a small biparietal diameter, a single umbilical artery or an abnormal retronasal triangle should raise the sonographer's suspicion of a congenital defect and warrant a more thorough fetal assessment, which often includes transvaginal scanning. Care should, however, be taken not to overinterpret first-trimester findings as false-positive rates of 3-4% have been reported. With more subtle findings, and especially if a heart defect is suspected, a sonographic reassessment after 15 weeks' gestation is indicated. Patients should be counseled that findings could worsen but also improve with time. Basic fetal anomaly screening should be recommended, piggybacked on the routine first-trimester (aneuploidy screening) ultrasound, both for low and high-risk populations. First-trimester anatomy screening seems particularly useful in obese women, whose fetuses are difficult to screen at the midtrimester ultrasound and in multiple gestation. Noninvasive prenatal testing using cell-free fetal DNA can complement but should not replace first-trimester ultrasound.

Distended jugular lymphatic sacs in fetuses with increased nuchal translucency: correlation with first-trimester findings in aberrant karyotypes

AbstractObjective: We investigated the prognostic relevance of ultrasound visibility of distendend jugular lymphatic sacs (JLS) in fetuses with aberrant karyotypes in First-trimester-screening. Furthermore we tried to differentiate between increased nuchal translucency (NT) and cystic hygroma colli.Methods: We performed a retrospective single center study in 1874 patients presenting for First-trimester-screening between 2009 and 2013. All fetuses with an abnormal risk calculation and NT > 2.5 mm (95th percentile) were reviewed for ultrasound visibility of JLS. A group of 30 fetuses with normal risk calculation served as control. Karyotyping was performed by chorionic-villi-sampling or amniocentesis, respectively.Results: In a total of 2030 fetuses 70 (3.44%) with pathologic first-trimester-screening results showed either aberrant karyotypes or severe ultrasound pathologies. Main aberrant karyotypes were trisomy 21 (25), trisomy 18 (16), trisomy 13(six), Monosomy X (four), 47, XYY or 47, XXX (three) and No...

Distended jugular lymphatic sacs in fetuses with increased nuchal translucency: correlation with first-trimester findings in aberrant karyotypes

Objective: We investigated the prognostic relevance of ultrasound visibility of distendend jugular lymphatic sacs (JLS) in fetuses with aberrant karyotypes in First-trimester-screening. Furthermore we tried to differentiate between increased nuchal translucency (NT) and cystic hygroma colli.Methods: We performed a retrospective single center study in 1874 patients presenting for First-trimester-screening between 2009 and 2013. All fetuses with an abnormal risk calculation and NT > 2.5 mm (95th percentile) were reviewed for ultrasound visibility of JLS. A group of 30 fetuses with normal risk calculation served as control. Karyotyping was performed by chorionic-villi-sampling or amniocentesis, respectively.Results: In a total of 2030 fetuses 70 (3.44%) with pathologic first-trimester-screening results showed either aberrant karyotypes or severe ultrasound pathologies. Main aberrant karyotypes were trisomy 21 (25), trisomy 18 (16), trisomy 13(six), Monosomy X (four), 47, XYY or 47, XXX (three) and Noonan’ syndrome (two). Distended JLS were visible in 47% of all cases. Statistical anaylsis found a significant correlation between NT and JLS size for the fetuses with trisomies 21, 18 and 13 (r = 0.53, p < 0.002). Cystic hygroma colli was present in all Turner and Noonan syndromes.Conclusions: Distended JLS have a strong correlation with abnormal karyotypes and increased nuchal translucency. Karyotyping should be offered in these cases.