Sonographic findings of trisomy 18 in the second trimester of pregnancy

Application of ultrasound combined with noninvasive prenatal testing in prenatal testing

BACKGROUND

Both noninvasive prenatal testing (NIPT) and prenatal ultrasound are widely used in clinical settings due to their safety, noninvasiveness, and accuracy, showing high detection rates for fetal chromosomal aneuploidies and structural abnormalities. However, whether the combined application of these two techniques has higher clinical applicability remains to be demonstrated.

METHODS

The clinical and laboratory data of 3,050 pregnant women who underwent NIPT were collected. The clinical feasibility and health economics of NIPT were investigated by analyzing the accuracy, postnatal follow-up results, and population applicability of NIPT. In addition, an analysis ultrasonography, NIPT, and karyotyping results were performed to evaluate the combined application of ultrasonography and NIPT in screening fetal chromosomal abnormalities.

RESULTS

NIPT could accurately detect trisomies 21, 18, and 13, and was highly sensitive and specific in detecting other autosomal and sex chromosomal aneuploidies. The positive rates of chromosomal abnormalities in the presence of 1 or 2 or more ultrasound markers were 7.5% and 29.2%, respectively, indicating that ultrasonography combined with NIPT should be preferred for the detection of fetal chromosomal abnormalities.

CONCLUSIONS

Health economic analysis revealed NIPT to be superior to conventional serologic screening in terms of accuracy and socioeconomics. Ultrasound and NIPT are complementary to each other and the combined techniques can improve the screening ability of fetal chromosomal abnormalities and provide clinicians with more diagnostic information.

The role of ultrasound in women with a positive NIPT result for trisomy 18 and 13

OBJECTIVE

The aim of this study was to evaluate the usefulness of ultrasound in pregnancies with a positive non-invasive prenatal testing (NIPT) result for trisomy 18/13.

MATERIALS AND METHODS

During a four-year period, the pregnant women who were referred for invasive genetic testing because of positive NIPT results for trisomy 18/13 were included in this study. An in-depth ultrasound was done for these patients before invasive procedures. The data of fetal ultrasound and cytogenetic results were collected.

RESULTS

There were 81 patients with a positive NIPT result for trisomy 18/13, including 39 (30 positive for trisomy 18; 9 positive for trisomy 13) within 12-14 weeks of gestation, and 42 (31 positive for trisomy 18; 11 positive for trisomy 13) within 15-22 weeks. The PPV of NIPT was 60.7% for trisomy 18, and 30% for trisomy 13, respectively. When adding ultrasound to NIPT, the new PPV for trisomy 18 was 100%, and the negative predictive value (NPV) was 92.3%, with a NPV of 85.7% in the first trimester and a NPV of 100% in the second trimester, respectively. The new PPV and NPV for trisomy 13 were 100% and 100%, respectively.

CONCLUSION

By adding ultrasound to the NIPT, we achieved much higher PPVs and NPVs for trisomy 18/13. A normal scan can help to alleviate stress in parents caused by false positive NIPT results.

Short Femur in the Second Trimester Scan Is Related to Maternal Preeclampsia and Small for Gestational Age Newborns

OBJECTIVE

To determine the contribution of short femur diaphysis length (FDL) at 19-22 weeks of gestation in the prediction of adverse pregnancy outcomes.

METHODS

The study included singleton pregnant women who underwent a routine anomaly scan at 19-22 weeks of gestation at the Virgen de la Arrixaca University Clinical Hospital (Murcia, Spain) between August 2011 and August 2012. Fetal biometry and Doppler ultrasound of uterine arteries were assessed as part of the anomaly scan, and the mean pulsatility index of both uterine arteries was recorded. Maternal obstetric characteristics, such as ethnicity, age, weight, parity, cigarette smoking, and medical history including hypertension and diabetes mellitus were collected from our database system.

RESULTS

A total of 6,366 women were included in the study after excluding cases with abnormal karyotype, major fetal abnormalities, or termination of pregnancy. There were 88 cases of preeclampsia (PE) (1.4%). Logistic regression was performed including maternal and fetal characteristics. Short FDL at 19-22 weeks was significantly associated with subsequent development of PE (OR = 0.89, 95% CI: 0.80-0.99, p = 0.025). The best model to predict PE from our sample included gestational age at scan, parity, maternal weight, chronic hypertension, mean pulsatility index in the uterine arteries, and FDL (AUC = 0.78, 95% CI: 0.71-0.84). Regarding small for gestational age (SGA) neonates, there were also significant differences in FDL and FDL <5th centile between the control group and SGA newborns below the 3rd, 5th, and 10th centile. In the groups of preterm births (delivery before 32, 34, and 37 weeks), there were no differences in FDL compared with the control group (term births).

DISCUSSION

Our results suggest that FDL at 19-22 weeks of gestation is an independent predictor of PE and SGA newborns.

Outcome of isolated fetal talipes: A systematic review and meta-analysis

INTRODUCTION

The aim of this systematic review was to explore the outcome of fetuses with a prenatal diagnosis of isolated talipes.

MATERIAL AND METHODS

Medline, Embase, Cinahl, and Clinicaltrials.gov databases were searched. The outcomes explored were: associated anomalies detected at follow-up ultrasound examination; fetal magnetic resonance imaging (MRI) and birth; chromosomal abnormalities detected with standard and chromosomal microarray analysis, intrauterine, neonatal, and perinatal death, and termination of pregnancy; rate of surgical and nonsurgical treatment; neurodevelopmental outcome; and false-positive rate of prenatal diagnosis. Meta-analyses of proportions were used to combine data.

RESULTS

Twenty-five studies (1567 fetuses) were included. Associated anomalies were detected in 7.8% (95% CI 0.1%-29.3%) of cases at follow-up ultrasound, and in 4.0% (95% CI 0.1%-13.2%) of cases, fetal MRI identified anomalies not detected at ultrasound assessment. Similarly, 7.0% (95% CI 3.4%-11.7%) of cases labeled as isolated talipes on prenatal imaging were found to have associated anomalies at birth. Abnormal karyotype was present in 3.6% (95% CI 1.7%-6.2%) of fetuses, whereas no anomaly was found at chromosomal microarray analysis, although this outcome was reported by only 1 study. Intrauterine death occurred in 0.99% (95% CI 0.4%-1.9%) of fetuses, whereas the corresponding figures for neonatal death and termination of pregnancy were 1.5% (95% CI 0.6%-2.6%) and 2.2% (95% CI 1.2%-3.4%), respectively. Surgical management of anomalies after birth was found in 41.7% (95% CI 27.0%-57.2%) of fetuses with isolated talipes, and 54.8% (95% CI 31.5%-77.0%) had nonsurgical management of the anomalies after birth. Abnormal neurodevelopmental outcome was reported in 7.6% (95% CI 1.0%-19.4%) of children, although this analysis was affected by the small number of included cases and short time of follow up.

CONCLUSIONS

Isolated talipes detected on prenatal ultrasound carries a generally good prognosis. The incidence of additional abnormalities detected on fetal MRI, aneuploidy, or neurodevelopmental disability is relatively low. However, longitudinal ultrasound assessment during pregnancy and a thorough postnatal evaluation are recommended to rule out associated anomalies that may significantly impact short- and long-term prognosis.

The indications for early prenatal diagnosis of trisomy 18: a 7-year experience at mainland China

Objective: To report the experience with first-trimester prenatal detection of pregnancies complicated by trisomy 18.Study design: Proven cases of trisomy 18 identified between 11 and 14 weeks of gestation were retrospectively reviewed. Information on maternal demographics, prenatal sonographic findings, indications for prenatal diagnosis and chromosomal analysis results was obtained by reviewing medical records.Results: During the 7-year period from January 2011 to December 2017, 89 cases of full trisomy 18 had first-trimester indications for prenatal diagnosis at Guangzhou Women and Children's Medical Center. Eighty-five (95.5%) had abnormal sonographic findings in the first trimester. The most common finding was increased nuchal translucency (55.1%), followed by cystic hygroma (18.0%), omphalocele (14.6%), and fetalis hydrops (11.2%). Four cases (4.5%) were not associated with any abnormal first-trimester sonographic finding, and were diagnosed because of routine positive screening results for trisomy 18. A single case was diagnosed because of a positive cell-free DNA (cfDNA) result.Conclusion: These results demonstrate that a large number of fetuses with trisomy 18 have abnormal sonographic findings in the first trimester, and support the continued utility of first-trimester sonographic examination in the diagnosis of this trisomy even with the availability of cfDNA.

Sensitivity of prenatal ultrasound for detection of trisomy 18

Objectives: To evaluate the sensitivity of prenatal ultrasound (US) for trisomy (T18) diagnosis and describe US findings in a large tertiary care institution in the USA. Materials and methods: This was a retrospective cohort of all T18 cases diagnosed at our institution from October 2004 to October 2014 based on prenatal or postnatal genetic diagnostic testing. We included all women with a fetus affected by T18 who had a comprehensive US by a maternal-fetal medicine specialist performed at our institution. US findings were reviewed, classified by organ system, and categorized as an anomaly or soft marker. Chi-square or t-test was used for statistical analysis. Results: We included 128 cases of T18 with confirmed cytogenetic analysis -110 (86%) of which were diagnosed prenatally or suspected by cell-free DNA and confirmed postnatally, and 18 of which underwent neonatal blood sampling alone. One hundred and twenty-one (95%) had at least one abnormal US finding. Anomalies were more frequently identified on US at ≥20 weeks as compared with <20 weeks (93% versus 76%; p = .004). The mean number of findings detected per fetus was 5.1 ± 3.0. Fetuses diagnosed by postnatal sampling alone had a similar number of US exams performed and number of abnormal findings compared to those diagnosed prenatally. Conclusion: Ninety-five percent of fetuses with T18 had at least one abnormal US finding. This sensitivity of is higher than reported in most prior studies, but is not 100%, and should be considered when counseling women regarding prenatal diagnosis of T18. Rationale: Historical detection rates for abnormal sonographic findings in trisomy 18 fetuses range from 70% to 100%. These studies are limited by small sample sizes. This is a contemporary study of ultrasound findings in a large group of women with confirmed trisomy 18 by prenatal or postnatal genetic diagnosis. We provide expansive detail on soft markers and anomalies broken down by organ-system and gestational age.

Facial profile markers in second- and third-trimester fetuses with trisomy 18

OBJECTIVES

To evaluate nasal bone length (NBL), maxilla-nasion-mandible (MNM) angle, fetal profile (FP) line, prenasal thickness (PT), prenasal thickness to nasal bone length (PT:NBL) ratio and prefrontal space ratio (PFSR) as markers of trisomy 18 in the second and third trimesters of pregnancy.

METHODS

The NBL, MNM angle, FP line, PT, PT:NBL ratio and PFSR were measured retrospectively from stored two-dimensional images or three-dimensional volumes of trisomy-18 fetuses, and were compared with our previously reported normal ranges for euploid fetuses. Additional ultrasound findings were noted at initial routine second-trimester scan and at subsequent advanced ultrasound examination performed after referral for karyotyping.

RESULTS

A total of 43 trisomy-18 fetuses were included in the analysis. At initial examination, median gestational age was 21 + 2 weeks. NBL and PT were correlated with gestational age (P < 0.001), but the other markers were not. Mean NBL, MNM angle, PT, PT:NBL ratio and PFSR were 3.76 mm, 16.67°, 4.25 mm, 1.39 and 0.87, respectively. The FP line was zero (normal) in 53.7% of cases and negative (abnormal) in 46.3%. All markers were significantly associated with trisomy 18, with the PT:NBL ratio yielding the highest detection rate (88.4%) followed by NBL (83.7%), MNM angle (56.4%), FP line (46.3%), PT (27.9%) and the PFSR (20.5%) (for a 5% false-positive rate for the continuous variables). Various combinations of the four best markers (NBL, FP line, MNM angle and PT:NBL ratio) yielded detection rates of between 72% and 95%. Structural anomalies were not detected in 22% of fetuses at the initial scan and in 2% at the advanced scan.

CONCLUSIONS

The PT:NBL ratio and NBL are robust second- and third-trimester markers for trisomy 18. A negative FP line has a 0% false-positive rate and the potential to differentiate between trisomy 18 and Down syndrome, as in the latter the FP line is often positive. No major anomaly was observed at the initial scan in about a quarter of trisomy-18 fetuses, underlining the role of second-trimester facial marker evaluation.

Outcome of fetuses with short femur length detected at second-trimester anomaly scan: a national survey

OBJECTIVE

To assess the relationship between the finding of fetal femur diaphysis length (FL) below the 5(th) percentile at the second-trimester scan and pregnancy outcome, in a population in which more than 90% of women attend first-trimester screening.

METHODS

This was a retrospective study of all Danish singleton pregnancies with a 17-22-week anomaly scan between 1 January 2008 and 30 June 2011. Information on FL and gestational age (GA) at anomaly scan, on birth weight and GA at delivery and on chromosomal abnormalities was obtained from the Danish Fetal Medicine Database.

RESULTS

Short FL was identified in 2718 (1.8%) of 147,766 fetuses and was present in 11 (16.2%) of the 68 fetuses affected by trisomy 21 (positive likelihood ratio (LR+) 8.8 (95% CI, 5.1-15.2)). Trisomy 13/18 and unbalanced autosomal structural abnormalities were also associated with a short FL in three (12.0%, LR+ 6.5 (95% CI, 2.3-18.9)) and eight (32.0%, LR+ 17.4 (95% CI, 9.8-30.9)) of the cases, respectively. The risk of a fetus having trisomy 21, trisomy 18, trisomy 13 or an unbalanced autosomal structural abnormality was 1 : 123 (95% CI, 79-192), given a short FL. Pregnancies with a fetus with short FL were more often affected by early preterm delivery (before 34 weeks) (5.6%; odds ratio (OR) = 4.2 (95% CI, 3.5-4.9)) and small-for-gestational-age (SGA) infants (13.9%; OR = 4.3 (95% CI, 3.8-4.8)).

CONCLUSION

Short FL at the second-trimester anomaly scan is associated with a significantly higher relative risk of chromosomal abnormalities, and a substantially higher absolute risk for SGA and early preterm delivery.

The role of ultrasound in the diagnosis of fetal genetic syndromes

The use of ultrasound in the prenatal diagnosis of fetal genetic syndromes is rapidly evolving. Advancing technology and new research findings are aiding in the increased accuracy of ultrasound-based diagnosis in combination with other methods of non-invasive and invasive fetal testing. Ultrasound as a screening tool for aneuploidy and other anomalies is increasingly being used throughout pregnancy, beginning in the first trimester. Given the number of recorded syndromes, it is important to identify patterns and establish a strategy for identifying abnormalities on ultrasound. These syndromes encompass a wide range of causes from viral, substance-linked, chromosomal, and other genetic syndromes. Despite the ability of those experienced in ultrasound, it is important to note that not all fetal genetic syndromes can be identified prenatally, and even common syndromes often have no associated ultrasound findings. Here, we review the role of ultrasound in the diagnosis of fetal genetic syndromes.

First-trimester sonographic findings in trisomy 18: a review of 53 cases

OBJECTIVE

To report our experience with first-trimester sonographic findings in pregnancies complicated by trisomy 18.

METHODS

Proven cases of trisomy 18 undergoing sonographic examination between 11 + 0 and 13 + 6 weeks of gestation were retrospectively identified. Information on maternal demographics, prenatal sonographic findings, and chromosomal analysis results was obtained by reviewing the ultrasound reports and medical records.

RESULTS

During the 12-year period from July 1997 to June 2009, 53 cases of full trisomy 18 had first-trimester sonographic examination performed at our institution. All but one fetus displayed one or more abnormal sonographic finding, most commonly increased nuchal translucency thickness (n = 48, 91%). Absent or hypoplastic nasal bone was documented in 53% of the fetuses in which this marker was specifically looked for. Structural anomalies included omphalocele in 11 (21%), abnormal posturing of the hands in three (6%), megacystis in two (4%), and abnormal four-chamber view of the heart in two (4%). Early-onset fetal growth restriction and bradycardia were documented in 14 (26%) and 4 (8%) of the cases, respectively.

CONCLUSIONS

Our study demonstrates that a large number of fetuses with trisomy 18 have abnormal sonographic findings in the first trimester. However, the sonographic features usually found in the second-trimester are difficult to detect at an early gestational age. The recognition of the specific first-trimester sonographic pattern of trisomy 18 may allow improved detection of this serious condition in early pregnancy.