Significance of septa in first trimester increased nuchal translucency thickness - Semantic Scholar
First-Trimester Cystic Hygroma: Relationship of Nuchal Translucency Thickness and Outcomes. Huang, Jin MD ; Leung, Tak Yeung MD ; Choy, Kwong Wai PhD. Ultrasound measurement of nuchal translucency (NT) thickness is part of first received an NT measurement as part of first trimester screening for trisomies 21, 13, and 18 . cystic hygroma is highly correlated with adverse perinatal outcome and this is . Relation between increased fetal nuchal translucency thickness and. First-trimester nuchal translucency (NT) measurement is a widely used technique to determine the risk of fetal aneuploidy. healthy outcome, as well as the variety of malformations and . found to be no correlation between NT thickness and the ductus .. der Putte, ) that in monosomy-X fetuses the cystic hygroma.
In a total of 78, pregnancies presumed to be normal chromosomally, there were 19 cases with diaphragmatic hernia, which was diagnosed at the initial or subsequent scans or at birth. See Chapter 3 for the pathophysiology of increased nuchal translucency in diaphragmatic hernia. Herniation of the liver diagnosed at weeks gestation In the studies on chromosomally normal fetuses with increased nuchal translucency Table 1 and Table 2the prevalence of exomphalos 11 inwas higher than that expected in the general population6,8,17,20, Although one study reported that, in fetuses with exomphalos, increased nuchal translucency signifies an underlying chromosomal defect31, it appears that, even in chromosomally normal fetuses with enlarged translucency, the prevalence of exomphalos is about 10 times higher than in the general population.
In achondrogenesis type I, which is more rare and is also autosomal recessive with severe shortening of the limbs, there is poor mineralization of both the skull and vertebral bodies as well as rib fractures. Courtesy from Claude Colin, MD - www.
Additionally, there are two case reports on the first-trimester sonographic diagnosis of achondrogenesis type II in high-risk pregnancies; both fetuses had increased nuchal translucency and short limbs that were abnormally positioned, with lack of movement32, Intelligence and life expectancy are normal. Prenatally, limb shortening usually becomes apparent only after 22 weeks of gestation.
In the studies reporting on chromosomally normal fetuses with increased nuchal translucency Table 1there were two cases with the condition13, The characteristic features are narrow chest and rhizomelic limb shortening. Limb shortening is mild to moderate and this may not become apparent until after 24 weeks of gestation.
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In some cases, there is mental handicap, which is thought to be secondary to inadequately treated hypoglycemia. In The Fetal Medicine Foundation Project Table 2one of the fetuses with increased nuchal translucency and exomphalos had Beckwith—Wiedemann syndrome In a case report of a week fetus with the syndrome, from a high-risk pregnancy, there was shortening of all limbs, narrow chest and increased nuchal translucency 6.
The pathogenesis is uncertain but possible causes include abnormal folding of the trilaminar embryo during the first 4 weeks of development, early amnion rupture with amniotic band syndrome, and early generalized compromise of embryonic blood flow.
In the studies on chromosomally normal fetuses with increased nuchal translucency Table 1 and Table 2the prevalence of body stalk anomaly 12 in was higher than that expected in the general population11,13, In a screening study involving ultrasound examinations at 11—14 weeks and 18—20 weeks of gestation in patients, there were two cases of body stalk anomaly and they were both diagnosed at the early scan; in one of the cases, there was increased nuchal translucency thickness The lower part of the body is in the celomic cavity and the upper part in the amniotic cavity In a multicenter study for chromosomal defects by nuchal translucency thickness and maternal age,fetuses were examined and 14 of these had body stalk anomaly The ultrasonographic features were a major abdominal wall defect, severe kyphoscoliosis and a short umbilical cord.
In all cases, the upper half of the fetal body was in the amniotic cavity, whereas the lower part was in the celomic cavity, suggesting that early amnion rupture before obliteration of the celomic cavity is a possible cause of the syndrome. Some of the affected genetically male individuals show a female phenotype.
Patients usually die in the neonatal period from pulmonary hypoplasia. In the studies reporting on chromosomally normal fetuses with increased nuchal translucency Table 1there was one case with the condition6. The curvature of the femur is visible, with a significant limb shortening and bowing.
In the studies reporting on chromosomally normal fetuses with increased nuchal translucency Table 1there was one case with the condition Affected children, particularly cases where early intervention has been demonstrated to improve prognosis, 22 could be delivered at units with suitable neonatal expertise. As part of prenatal counseling, termination of pregnancy is often discussed with parents, particularly in cases where CHD is severe.
Although the second trimester sonogram is a valuable tool in prenatal CHD screening, increasing numbers of studies suggest high performance in the late first trimester or even earlier. However, it must be acknowledged that even in experienced hands some CHD remain undetected.
An effective strategy for prenatal screening includes an early detection, improved antenatal, intrapartum, and postnatal management reducing morbidity for survivors. Since the introduction of the NT as screening marker for fetal aneuploidies, the list of genetic syndromes presenting with an increased NT is rapidly growing.
The most frequent syndromes frequently associated with increased NT in the first trimester are Noonan syndrome, Smith—Lemli—Opitz syndrome, di George syndrome, achondrogenesis, myotonic dystrophy, and some other musculoskeletal disorders.
Most of SGD are relatively rare and are reported in large cohorts of fetuses from unselected populations with increased NT. Recently, the predictive value of increased NT for SDG was assessed in selected pregnancies at risk. The mutation was previously identified in one of the parents in most cases. In a few cases, prenatal diagnosis was carried out because of a risk of germinal mosaicism after de novo mutation in an offspring affected by a dominant single-gene disorder. Monochorionic twin pregnancies were excluded because of the confounding effect on an increased NT of both conditions.
Chorionic villus sampling CVS was performed in all pregnancies. The measurement of fetal NT had no association with fetal diagnosis of X-fragile mental retardation syndrome, Huntington disease, and Duchenne muscular dystrophy in these pregnancies as no differences were found between the 63 affected and non-affected fetuses. Alterations of extracellular matrix could explain this finding in inherited metabolic disorders. Authors concluded that regardless of these associations, it is likely that invasive procedures will remain the standard approach for pregnancies at high risk of SGD.
As the failure to detect any pregnancies affected by four of the five conditions suggests that the association of these SGD with increased NT is likely to be less than 1 inauthors doubt the utility of population screening.
Noteworthy, they conclude that the anxiety of patients generated by the knowledge of increased NT can be reduced if the pregnancy is predicted not to be affected with the conditions comprising the current panel. The largest studies published after the year of structural anomalies and genetic disorders detected in euploid fetuses with increased NT are displayed in Table 1. Adapted from Increased nuchal translucency in euploid fetuses—what should we be telling the parents?
NR, not reported; NT, nuchal translucency.
Significance of septa in first trimester increased nuchal translucency thickness
The risk of any pregnancy complication including the most serious such as fetal or neonatal death in monochorionic twin pregnancies is substantially higher than in dichorionic twins. Intertwin vascular anastomoses are present in virtually all monochorionic placentas and may potentially lead to acute or chronic imbalances between the circulations.
Monochorionic placentation is the serious pregnancy abnormality which is far more common than fetal malformations. TTTS develops when there is the abnormal blood transfusion from the donor twin to the recipient twin in cases when the interfetal anastomoses fail to balance the two circulations.
The early first trimester imbalance in the blood flow through the intertwin vascular anastomoses may result in subtile early cardiac failure of the recipient twin leading to the increased NT. If the imbalance is not self-corrected, the most common result is early fetal death rather than TTTS which occurs later in pregnancy.
[Full text] Clinical utility of nuchal translucency screening | RRN
This same observation was confirmed in a larger cohort of monochorionic pregnancies with relatively high predictive value for TTTS. This limits the use of NT as an exclusive screening method for identification of those monochorionic pregnancies that are developing TTTS and thus would require closer follow-up and possibly eventual laser treatment.
Additionally, assessment of DV flow requires proper ultrasound equipment and high expertise of the operator. If a progressively asymmetrical vascular pattern develops, then second trimester features of TTTS will appear.
Monozygotic twin pairs may have discordant karyotypes heterokaryotypia which may result from a mitotic error arising either before twinning, resulting in a mosaic, or after splitting, resulting in the chromosomal abnormality in one of the fetuses. However, Cuckle and Maymon have recently described a method for calculating fetus-specific Down syndrome risks from a series of unaffected twins after adjustment for sonographer bias using its own NT value as well as that of the co-twin taking into consideration zygosity, chorionicity, maternal age, ethnical origin, and fetal sex.
In dichorionic twins, a fetus specific risk should be calculated. Chromosomal defects can be ruled out by karyotyping. Structural abnormalities are usually diagnosed at the second trimester ultrasound scan. A narrower use of the term refers to a disorder of brain function that affects emotion, learning ability, self-control, and memory unfolding later during the growth. Neurodevelopmental disorders may manifest as behavioral and cognitive problems. Thus, these disorders occur later in childhood than structural anomalies.
A definitive neurodevelopmental diagnosis usually requires long follow-up with repeat examinations. Several studies have been published about the long-term neurodevelopmental outcome of children with increased NT. Comparison of the studies is difficult due to small study populations and variable NT cutoff levels and methods. According to the most recent publications, the neurological outcome of children after increased fetal NT seems to be favorable by the age of 24 months.
Some authors have proposed that, in fetuses with enlarged NT and obvious structural major anomalies, termination of pregnancy may be offered directly to save the cost of karyotyping. This approach is not acceptable unless parents are reluctant to undergo karyotyping after counseling in contemporary perinatal practice for several reasons: In fetuses with grossly enlarged NT, cystic hygroma or hydrops, ultrasound should be performed again at 15 weeks to ensure fetal viability.
In euploid fetuses with continuation of pregnancies, third level detailed ultrasound assessment of fetal anatomy with special attention to fetal echocardiography should be offered around 20 weeks. In cases of any major structural anomaly, a multidisciplinary team should be involved in counseling, pregnancy follow-up, timing and organizing delivery in the third-level prenatal center with high quality neonatal care.
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Intrauterine treatment should be offered, if possible. In the case of intrauterine demise, fetal autopsy and other investigations to reveal etiology of increased NT should be a standard care followed by proper counseling. Psychological support to the family should not be ignored. There is no general consensus on how to proceed after birth in pregnancies with euploid fetuses without obvious structural anomalies.