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Products of Conception
Published in Carlos Simón, Carmen Rubio, Handbook of Genetic Diagnostic Technologies in Reproductive Medicine, 2022
Nasser Al-Asmar, Marcia Riboldi
The authors showed that there was a 33% overall discordant rate between results due to maternal cell contamination, balanced chromosome rearrangements, polyploidy, and placental mosaicism. Regardless of the platform utilized, mosaicism was detected in 18% of samples (33). Specifically, confined placental mosaicism (CPM) is characterized by the discrepancy between the chromosomal/genetic makeup of the fetus and the placenta. Approximately 2% of viable pregnancies studied by chorionic villus sampling (CVS) at 9 to 11 weeks of gestation are confined to the placenta (33).
Fetal Growth Restriction
Published in Vincenzo Berghella, Maternal-Fetal Evidence Based Guidelines, 2022
Juliana Gevaerd Martins, Alfred Abuhamad
Suboptimal placental perfusion is the most common pathology associated with FGR (30–40% of all cases) [5]. Placental disorders (abruption, hemangioma, chorioangioma and circumvallate shape) and umbilical cord abnormalities (velamentous or marginal cord insertion, single umbilical artery) have also been associated with FGR [8]. In over 20% of fetuses with idiopathic FGR, confined placental mosaicism was detected in the placenta [3].
Chorionic villus sampling
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Giovanni Monni, Maria Angelica Zoppi, Carolina Axiana
Currently, confined placental mosaicism is considered the main cause of ambiguous results, which might result in false-positive diagnoses. Following the direct analysis, the majority of discordant findings between chorionic villus samples and the fetus have been false-positive results (1–2%) and only very few have been false negative (1/3000).
The predictive value of noninvasive prenatal screening for copy number variations: a cohort study and a systematic meta-analysis
Published in Expert Review of Molecular Diagnostics, 2023
Li Wen, Yanzhen Zhang, Jiye Gao, Wensheng Hu
Nevertheless, compared with the screening performance of NIPS for common trisomies, this PPV finding is relatively unsatisfactory. It may lead to a relative increase in the number of unnecessary invasive procedures, thus expanding NIPS to screen for the entire genome is controversial from a clinical perspective. Confined placental mosaicism (CPM), which occurs in approximately 2% of all pregnancy [44], is an important cause for the discordant results and also a limitation of NIPS. It is well known that cfDNA is mainly derived from the cytotrophoblast cells [45], increased risk of CNVs detected by NIPS may be due to the presence of CPM rather than true fetal abnormalities. For this reason, it is important to carefully consider the specimen source for invasive diagnostic testing. For pregnancies with abnormal NIPS results, invasive prenatal diagnostic tests such as amniocentesis or cordocentesis should be performed for further investigation to avoid false-positive results leading to unnecessary pregnancy termination.
Value of Placental Examination in the Diagnostic Evaluation of Stillbirth
Published in Fetal and Pediatric Pathology, 2022
Developmental lesions, observed in 12% of our cases, were consistent with villous maturation abnormalities of non-ischemic origin. The causal relationship between delayed villous maturation (DVM) and stillbirth is still debated. It is not clear whether the fetal death is directly related to this placental anomaly or other associated pathogenic processes [40]. The strong association between DVM and obesity, gestational or pre-gestational maternal diabetes is reported in some studies [41,42]. In these conditions, DVM is thought to be due to excessive stimulation of placental growth by insulin and other growth factors with the detrimental effects on the villous maturation [41]. The association of DVM with histologic features of chromosomal aberration in both malformed and non-malformed fetuses of our series supports a genetic, especially chromosomal, cause for DVM [41]. A chromosomal aberration (trisomy 18) was diagnosed in two cases, where the fetal death occurred before the pregnancy termination. The proportion of chromosomal abnormalities in our stillbirth population was, however, underestimated as 5% of the fetuses had polymalformative syndromes, none of which were cytogenetically investigated. This limitation didn’t unfortunately allow us to establish a genotype–phenotype correlation or provide adequate genetic counseling for families. It’s also noteworthy that, in the absence of placental karyotyping, it was not possible to diagnose a confined placental mosaicism which might explain the DVM in non-malformed fetuses of our series [43].
Prenatal diagnosis of trisomy 22 at the first trimester of pregnancy
Published in Journal of Obstetrics and Gynaecology, 2020
Bi-Qiu Xu, Xiao-Cui Jiang, Li Wan, Sha Wang, Yan-Dong Yang, Dong-Zhi Li
There are some limitations to this study. Information from cytotrophoblast was not available in the chromosome preparation from placental samples; so that the possible causes of a false-negative cfDNA result for trisomy 22 could not be explored. Furthermore, the mosaic trisomy 22 (with a low percentage of normal trisomy 22 in the placenta or amniotic fluid cells) could not be excluded in this case. Only a relatively small number of cells from a long-term culture were studied. The differentiation between non-mosaic and mosaic trisomy 22 is very important for genetic counselling and for the explanation of some surviving non-mosaic cases with confined placental mosaicism. Nevertheless, this case report highlights the importance of pre-test counselling for patients who are considering having cfDNA testing. It also highlights the relevance of a detailed early anatomy scan when an extremely higher screening risk for common triosmies, even with a normal NT, is encountered. This report may provide some useful information for the prenatal diagnosis and the management of similar cases.