Clinical value of screening prenatal ultrasound combined with chromosomal microarrays in prenatal diagnosis of chromosomal abnormalities

Abstract

Objective

To evaluate the clinical value of ultrasound findings in the screening of fetal chromosomal abnormalities and the analysis of risk factors for chromosome microarray analysis (CMA) abnormalities.

Methods

We retrospectively analyzed the datasets of 15,899 pregnant women who underwent prenatal evaluations at Affiliated Maternity and Child Health Care Hospital of Nantong University between August 2018 and December 2022. Everyone underwent ultrasound screening, and those with abnormal findings underwent CMA to identify chromosomal abnormalities.

Results

The detection rates for isolated ultrasound anomalies and combined ultrasound and CMA anomalies were 11.81% (1877/15,899) and 2.40% (381/15,899), respectively. Among all ultrasound abnormalities, detection rates for isolated ultrasound soft marker anomalies, isolated structural abnormalities, and both ultrasound soft marker anomalies with structural abnormalities were 82.91% (1872/2258), 15.99% (361/2258), and 1.11% (25/2258), respectively. The detection rate of abnormal chromosomes in pregnant women with abnormal ultrasound results was 16.87% (381/2258). The detection rates were 13.33% in cases with two or more ultrasound soft markers anomalies, 47.37% for two or more structural anomalies, and 48.00% for concomitant ultrasound soft marker and structural anomalies.

Conclusions

Enhanced detection rates of chromosomal anomalies in fetal malformations are achieved with specific ultrasound findings (NT thickening, cardiovascular abnormalities, and multiple soft markers) or when combined with high-risk factors (advanced maternal age, familial history, parental chromosomal anomalies, etc.). When the maternal age is over 35 and with ≥2 ultrasound soft marker anomalies accompanied with any high-risk factors, CMA testing can aid in the diagnosis of prenatal chromosomal abnormalities.

Keywords:

• Congenital malformations
• prenatal diagnosis
• ultrasound
• chromosome microarray analysis
• soft marker

1. Introduction

Prenatal diagnosis constitutes a pivotal facet of genetic assessment, employing techniques spanning cytogenetics, molecular biology, and imaging and so on [1]. Its core objective is to evaluate the developmental trajectory of fetuses exhibiting suspected congenital anomalies within the uterine milieu. This endeavor facilitates the timely identification of hereditary disorders, offering a platform for subsequent intrauterine interventions or judicious decisions regarding selective pregnancy termination. Chromosome microarray analysis (CMA) encompasses methodologies encompassing comparative genomic hybridization and single nucleotide polymorphism microarray analysis [2]. In contrast to conventional karyotype analysis, CMA offers manifold advantages including heightened resolution, enhanced efficiency, heightened sensitivity, and elevated precision. Its prowess is particularly pronounced within the context of genetic perturbations such as microdeletion and microduplication syndromes. Furthermore, CMA effectively discerns variations in gene copy numbers, referred to as copy number variations (CNVs) [3–5]. Given that chromosomal aberrations represent a prevalent etiological factor underpinning fetal birth defects, accounting for 2.9% of cases, with chromosomal numerical abnormalities being particularly prevalent, timely identification of fetal chromosomal anomalies emerges as a potent strategy for mitigating the incidence of congenital malformations [6]. In this realm, CMA assumes a pivotal role within the domain of prenatal diagnosis for fetal congenital malformations. Traditionally, inheritance examination mainly analyzes fetal chromosomal assessment after collecting amniotic fluid (amniocentesis), umbilical cord blood (umbilical vein puncture), or villous tissue (villus puncture). However, genetic examination is an interventional diagnosis, and there are certain risks. Studies found that amniocentesis-related fetal miscarriage rates ranged from 0.6% to 0.86%, and the miscarriage rate of umbilical vein puncture was from 0.4% to 3.6% [7–12]. It seems that these techniques engender varying degrees of impact upon expectant mothers, potentially culminating in intrauterine infections or even spontaneous abortions [13].

The progressive advancement of prenatal ultrasound diagnostic technologies has ushered in a paradigm shift. This evolution has enabled the timely identification of an increasing array of congenital malformations. Notably, beyond overt structural anomalies, inconspicuous and nonspecific deviations within ultrasound-derived ultrasound soft markers assume salience within the realm of fetal congenital malformation diagnosis [14–17]. Scholarly inquiries have underscored the intimate association between ultrasound-detected structural and soft marker anomalies and fetal chromosomal aberrations, and a heightened incidence of chromosomal anomalies is discernible when two or more indices manifest as aberrant [18,19]. Against this backdrop, the current study endeavors to scrutinize the interplay between ultrasound findings and CMA outcomes within the context of diagnosing chromosome abnormality. Furthermore, we explored the risk factors for abnormal CMA results based on analysis of different ultrasound findings and patient factors.

2. Methods

2.1. Research population

A total of 15,899 pregnant women who underwent prenatal assessments at Affiliated Maternity and Child Health Care Hospital of Nantong University between August 2018 and December 2022 were included in this study. Variables recorded encompassed maternal age, gestational age, pregnancy history pertaining to smoking and drinking, as well as birth history. Additionally, occurrences of noninvasive screening testing (NIST) abnormalities, trisomy 21 abnormalities, adverse pregnancy history, parental chromosomal abnormalities, and familial history of congenital malformations were documented.

NIST employs CMA testing, and the presence of aberrant CMA nodes indicates an elevated risk for trisomy 21, trisomy 18, trisomy 13, other autosomal aneuploidies, sex chromosome aneuploidies, and CNV syndrome.

2.2. Inclusion and exclusion criteria

Inclusion criteria encompassed: (1) singleton pregnancies; (2) clinical judgments for CMA were based on: identification of structural abnormalities on prenatal ultrasound, inconclusive fetal karyotype analysis in identifying chromosomal abnormalities, or cases of intrauterine fetal death or still birth [20]; (3) comprehensive understanding of the study, accompanied by informed consent.

Exclusion criteria consisted of: (1) pregnant women deemed at high risk according to noninvasive prenatal screening; (2) pregnant women contraindicated for amniocentesis; (3) pregnant women afflicted by severe pregnancy complications, such as hyperthyroidism, hypothyroidism, or gestational hypertension; (4) pregnant women with incomplete information.

2.3. Ultrasound methodology

The ultrasound methodology is conducted during the gestational period of 11⁺⁰ to 13⁺⁶ weeks. Utilizing the GE Voluson E8 color ultrasonographic diagnostic apparatus, ultrasound examinations were performed at a transducer frequency range of 3.5–5.0 MHz. Employing a supine position, abdominal scans were conducted to scrutinize fetal system malformations. Organs including thoracic and abdominal structures, the spine, face, and other solid organs were meticulously examined. Measurement of fetal heart metrics, amniotic fluid levels, fetal heart rate, femur and humerus lengths, abdominal circumference, biparietal diameter, and head circumference was also executed. The scope of soft marker items encompassed nuchal transparency (NT) or nuchal fold (NF) thickening, choroid plexus cyst, nasal bone deficiency or incomplete ossification, lateral ventricular dilation, left ventricular hypertonic spots, single umbilical artery, renal pelvis dilation, and hyperechoic bowel [21,22].

We conducted a comprehensive analysis and verification of all the reports in this study, enlisting the collaboration of at least two chief technologists to jointly assess and review the ultrasound findings. In cases where significant discrepancies were observed in the test results, we involved a third doctor to measure and analyze them, ensuring that the final outcomes are released following thorough evaluation by more than three senior ultrasound specialists.

2.4. CMA examination and result determination

The Affymetrix CytoScan chip kit was utilized for comprehensive analysis and processing of the patient’s entire genomic DNA. The genomic DNA digestion, ligation, amplification, purification, fragmentation, labeling, hybridization, and washing steps were meticulously performed in strict accordance with standardized protocols provided by Affymetrix (Santa Clara, CA). The presence of aberrant CMA nodes indicates an elevated risk for trisomy 21, trisomy 18, trisomy 13, other autosomal aneuploidies, sex chromosome aneuploidies, and CNV syndrome.

Data underwent analysis via Chromosome Analysis Suite (ChAS) software. The analysis was cross-referenced with established databases including Clingene (https://www.clinicalge-nome.org), ClinVar (https://www.ncbi.), DECIPHER (https://decipher.sanger.ac.uk), DGV (http://dgv.tcag), OMIM (http://omim.org), and PubMed (http://www.ncbi.nlm.) to identify abnormal CNVs and chimerisms. CMA results were reported based on the International System for Human Cytogenetics Nomenclature (ISCN) for chromosomal number and genomic CNV [23]. CNVs were classified as pathogenic CNVs (pCNVs), likely pathogenic CNVs (likely pCNVs), variants of unknown significance (VOUS CNVs), likely benign CNVs (likely bCNVs), or benign CNVs (bCNVs), based on pathogenicity.

2.5. Statistical analysis

SPSS 25.0 software (SPSS Inc., Chicago, IL) was employed for data analyses. Normally distributed measurement data were presented as mean ± standard deviation, while categorical data were expressed as frequency and percentage. Binary logistic regression was performed to ascertain correlations between maternal factors, pregnancy history, genetic abnormalities, ultrasound indices, and fetal chromosomal anomalies. Multivariate logistic regression analyses were performed to ascertain the interaction of potential factors, including advanced age, family history of congenital malformations, parental chromosomal abnormalities, adverse pregnancy history, trisomy 21 abnormalities, NIST anomalies, number of high risk except for advanced age, number of ultrasonographic soft markers ≥2, abnormal soft markers of ultrasound + abnormal structure of ultrasound, and the correlations between these factors and fetal chromosomal anomalies. Significance was established at p < .05 (Figure 1).

Figure 1. The subject selection process and relevant inclusion criteria.

3. Results

3.1. Demographic characteristics and clinical profiles of research subjects

Among the cohort, 13,641 pregnant women exhibited normal ultrasound findings, while the detection rate of those with isolated ultrasound anomalies was 11.81% (1877/15,899), and the co-occurrence of ultrasound and CMA abnormalities was observed in 2.40% (381/15,899). The average ages for women with normal ultrasound findings, isolated abnormal ultrasound results, and concurrent abnormal ultrasound and CMA results were (30.52 ± 4.02), (32.68 ± 4.59), and (34.52 ± 4.78) years. The mean gestational ages for the respective groups undergoing CMA testing were (20.01 ± 2.01), (21.03 ± 2.00), and (20.97 ± 2.04) weeks. The isolated ultrasound anomalies group exhibited a higher proportion of women with pregnancy history, accounting for 25.57% (480/1877). Additionally, the proportions of NIST abnormalities, trisomy 21 abnormalities, adverse pregnancy history, parental chromosomal abnormalities, and family history of congenital malformations varied across the three groups, with the ultrasound and CMA abnormalities group exhibiting the highest proportions in most cases (see Table 1).

Table 1. Basic data and characteristics of pregnant women.

Variables		Normal ultrasound findings	Ultrasound structural abnormalities	Isolated ultrasound anomalies	Ultrasound and CMA abnormalities
Number, N (%)		13,641 (85.80)	386 (2.4)	1877 (11.81)	381 (2.40)
Age (years)		30.52 ± 4.02	32.9 ± 4.6	32.68 ± 4.59	34.52 ± 4.78
Age >35 years		1920 (14.08)	133 (34.46)	613 (32.66)	171 (44.88)
Gestational ages (weeks)		20.01 ± 2.01	20.15 ± 2.00	21.03 ± 2.00	20.97 ± 2.04
Pregnancy history		2637 (19.33)	82 (21.24)	480 (25.57)	52 (13.65)
High-risk factors	NIST anomalies	55 (0.4)	49 (12.69)	90 (4.79)	68 (17.85)
	Trisomy 21 abnormalities	64 (0.47)	27 (6.99)	97 (5.17)	55 (14.44)
	Adverse pregnancy history	77 (0.56)	34 (8.81)	152 (8.1)	57 (14.96)
	Parental chromosomal abnormalities	15 (0.11)	18 (4.66)	51 (2.72)	29 (7.61)
	Family history of congenital malformations	24 (0.18)	6 (1.55)	28 (1.49)	31 (8.14)

3.2. Ultrasound findings

As shown in Table 2 and Figure 2, abnormal ultrasound results accounted for 14.20% (2258/15,899) of the total number of research subjects, among which that 82.91% (1872/2258) were single soft marker abnormalities, 15.99% (361/2258) were single structural abnormalities, and 1.11% (25/2258) were a combination of soft markers and structural abnormalities. The most common abnormalities of ultrasonographic soft markers are NT/NF thickening, and the detection rate of NT thickening which was from 3.0 mm to 4.0 mm, and NF thickening which was from 6.0 mm to 7.0 mm, was the broadening case with the highest detection rate. The detection rate of incomplete ossification of nasal bone deficiency/incomplete ossification also has a high detection rate. It is worth noting that the detection rate of abnormalities of two or more soft markers at the same time was 2.66% (60/2258), which was higher than that of most single soft markers.

Figure 2. Pictures of abnormal ultrasound result. (A) Broadening of lateral ventricle. (B) Ventricular septal defect. (C) Cleft lip and palate. (D) Dilatation of the bowel. (E) Varus foot. (F) The left ventricle exhibited hypoplasia.

Table 2. Distribution of abnormal ultrasound results.

Variables		Number	Proportion of ultrasound abnormalities (%)	Proportion of total research subjects (%)
Ultrasonographic abnormality	Simple ultrasound soft markers abnormality	1872	82.91	11.77
	Simple ultrasonographic structural abnormality	361	15.99	2.27
	Abnormal soft markers of ultrasound + abnormal structure of ultrasound	25	1.11	0.16
	Total number	2258	100.00	14.20
Simple ultrasound soft markers abnormality	2.5 mm ≤ NT < 3.0 mm	232	10.27	1.46
	3.0 mm ≤ NT < 4.0 mm	275	12.18	1.73
	NT ≥ 4.0 mm	71	3.14	0.45
	6.0 mm ≤ NF < 7.0 mm	633	28.03	3.98
	7.0 mm ≤ NF < 8.0 mm	159	7.04	1.00
	NF ≥ 8.0 mm	35	1.55	0.22
	Choroid plexus cyst	12	0.53	0.08
	Nasal bone deficiency/incomplete ossification	142	6.29	0.89
	Lateral ventricular dilation	95	4.21	0.60
	Hyperechoic bowel	49	2.17	0.31
	Single umbilical artery	28	1.24	0.18
	Renal pelvis dilation	25	1.11	0.16
	Growth restriction	36	1.59	0.23
	Others	20	0.89	0.13
	≥2 markers	60	2.66	0.38
Simple ultrasonographic structural abnormality	Cardiovascular system	127	5.62	0.80
	Nervous system	10	0.44	0.06
	Limb deformity	26	1.15	0.16
	Facial abnormalities	18	0.80	0.11
	Urinary system	55	2.44	0.35
	Digestive system	28	1.24	0.18
	Respiratory system	35	1.55	0.22
	Others	24	1.06	0.15
	≥2 systems	38	1.68	0.24

In the results of ultrasonographic structural abnormalities, cardiac system abnormalities were the most common, with a detection rate of 5.62% (127/2258). And the detection rate of structural abnormalities of two or more systems is 1.68% (38/2258), which is also more than that of most single system structural abnormalities.

3.3. Chromosome microarray analysis results

CMA analysis unveiled abnormal results in 381 out of the 2258 pregnant women tested, yielding a detection rate of 16.87%. The proportion of all research subjects in our survey was slightly 2.40% (381/15,899).

Chromosomal number abnormalities accounted for 19.42% (74/381) of CMA abnormalities, while CNVs accounted for 80.58% (307/381). Among them, the detection rate of trisomy 21 was the highest in the abnormal chromosome number, yielding a detection rate of 12.07% (46/381). And bCNVs were the highest detection item in CNVs, with the proportion of 24.41% (93/381). A total of 74 cases of pCNVs and likely pCNVs were detected in pregnant women with abnormal ultrasound (see Table 3).

Table 3. A distribution of abnormal CMA results.

Variables		Number	Proportion of CMA abnormalities (%)	Proportion of ultrasound abnormalities (%)	Proportion of total research subjects (%)
Chromosome number abnormality	Trisomy 21	46	12.07	2.04	0.29
	Trisomy 18	11	2.89	0.49	0.07
	Sex chromosome abnormality	15	3.94	0.66	0.09
	Others	2	0.52	0.09	0.01
	Total number	74	19.42	3.28	0.47
CNVs	pCNVs	31	8.14	1.37	0.19
	Likely pCNVs	43	11.29	1.90	0.27
	VOUS CNVs	69	18.11	3.06	0.43
	Likely bCNVs	71	18.64	3.14	0.45
	bCNVs	93	24.41	4.12	0.58
	Total number	307	80.58	13.6	1.93
Total number		381	100.00	16.87	2.40

3.4. CMA results and ultrasound anomalies

Table 4 elucidates the CMA result distributions of abnormal chromosome number and pCNVs/likely pCNVs within the context of abnormal ultrasound results. Notably, among the ultrasound soft marker abnormalities, NT thickening (exceeds 3 mm) and nasal bone deficiency/incomplete ossification are the much more salient indicators of chromosomal abnormality. Detection rates were markedly elevated for CMA abnormalities when two or more soft marker anomalies were present, achieving 13.33% (8/60).

Table 4. Distribution of CMA results of pregnant women with abnormal ultrasound results.

Ultrasonographic abnormality		Number	Chromosomal abnormalities	Detection rate (%)	Chromosome number abnormality	pCNVs/likely pCNVs
Simple ultrasound soft markers abnormality	2.5 mm ≤ NT < 3.0 mm	232	11	4.74	7	4
	3.0 mm ≤ NT < 4.0 mm	275	34	12.36	18	16
	NT ≥ 4.0 mm	71	9	12.68	7	2
	6.0 mm ≤ NF < 7.0 mm	633	16	2.53	10	6
	7.0 mm ≤ NF < 8.0 mm	159	0	0.00	0	0
	NF ≥ 8.0 mm	35	1	2.86	0	1
	Choroid plexus cyst	12	0	0.00	0	0
	Nasal bone deficiency/incomplete ossification	142	9	6.34	2	7
	Lateral ventricular dilation	95	1	1.05	0	1
	Hyperechoic bowel	49	1	2.04	0	1
	Single umbilical artery	28	1	3.57	0	1
	Renal pelvis dilation	25	1	4.00	0	1
	Growth restriction	36	1	2.78	0	1
	Others	20	0	0.00	0	0
	≥2 markers	60	8	13.33	1	7
Simple ultrasonographic structural abnormality	Cardiovascular system	127	10	7.87	3	7
	Nervous system	10	0	0.00	0	0
	Limb deformity	26	0	0.00	0	0
	Facial abnormalities	18	1	5.56	1	0
	Urinary system	55	4	7.27	2	2
	Digestive system	28	0	0.00	0	0
	Respiratory system	35	0	0.00	0	0
	Others	24	10	41.67	7	3
	≥2 systems	38	18	47.37	13	5
Abnormal soft markers of ultrasound + abnormal structure of ultrasound		25	12	48.00	3	9
Total number		2258	148	6.55	74	74

Among ultrasound structural abnormalities, cardiovascular anomalies exhibited the highest detection rate for CMA abnormalities (7.87%, 10/127). Detection rates were also markedly elevated for CMA abnormalities when two or more ultrasound structural abnormalities were present, yielding a detection rate of 47.37% (18/38). Moreover, the detection rate for combined CMA abnormalities among pregnancies with both ultrasound soft marker and structural anomalies reached 48.00% (12/25), surpassing the rate for isolated ultrasound structural anomalies.

3.5. CMA detection rate of NT/NF thickening under different factors

It was further analyzed in this study since the results of the study showed a high detection rate of NT/NF thickening. As shown in Table 5, among the patients with ultrasound soft marker results showing NT thickening, pregnant women with other soft marker abnormalities (22.5%, 9/40) or advanced maternal age (18.37%, 9/49) had the highest detection rate of chromosome abnormalities, both of which were significantly higher than pregnant women without other high-risk factors. The detection rate of chromosomal abnormalities in pregnant women with NF thickening combined with other soft marker abnormalities (3.47%, 5/144) or in advanced maternal age (3.57%, 1/28) was also higher than that in pregnant women without other risk factors.

Table 5. Results of CMA detection rate of NT/NF thickening under different factors.

Ultrasonographic abnormality	Amalgamative high-risk factors	Number	Chromosomal abnormalities	Detection rate (%)
NT thickening	Advanced age	49	9	18.37
	Amalgamation of bad pregnancy history	22	1	4.55
	Other abnormal soft markers of ultrasound	40	9	22.50
	No other factors are incorporated	450	40	8.89
NF thickening	Advanced age	28	1	3.57
	Amalgamation of bad pregnancy history	21	0	0.00
	Other abnormal soft markers of ultrasound	144	5	3.47
	No other factors are incorporated	715	16	2.24

3.6. Univariate and multivariate logistic regression analysis of fetal chromosome abnormalities

Tables 6 and 7 encapsulate the results of correlation analysis. Logistic regression was employed to investigate potential factors predisposing fetal chromosomal abnormalities. The analysis disclosed that both isolated and combined ultrasound soft marker and structural anomalies, number of ultrasonographic soft markers ≥2, family history of congenital malformations, parental chromosomal abnormalities, adverse pregnancy history, NIST anomalies, and advanced maternal age were all significant factors correlated with fetal chromosomal abnormalities. Notably, pregnant women with advanced maternal age, number of ultrasonographic soft markers ≥2 and one or more high risk factors are more likely to detect fetal chromosome abnormalities (p < .05).

Table 6. Results of univariate logistic regression analysis of fetal chromosome abnormalities.

Predictor	Univariables OR (95% CI)	p Value
Advanced age	4.17 (3.40–5.13)	<.001
Family history of congenital malformations	26.34 (16.68–41.61)	<.001
Parental chromosomal abnormalities	19.29 (12.31–30.23)	<.001
Adverse pregnancy history	11.75 (8.61–16.02)	<.001
Trisomy 21 abnormalities	16.09 (11.63–22.28)	<.001
NIST anomalies	23.03 (16.91–31.37)	<.001
Number of high risk except for advanced age	15.91 (13.02–19.42)	<.001
Number of ultrasonographic soft markers ≥2	41.28 (24.61–69.24)	<.001
Abnormal soft markers of ultrasound + abnormal structure of ultrasound	63.56 (28.36–142.42)	<.001

Table 7. Results of multivariate logistic regression analysis of fetal chromosome abnormalities.

Predictor	Multivariables OR (95% CI)	p Value
Advanced age	2.90 (2.28–3.69)	<.001
Number of high risk except for advanced age	14.28 (11.62–17.55)	<.001
Number of ultrasonographic soft markers ≥2	18.62 (10.09–34.38)	<.001
Abnormal soft markers of ultrasound + abnormal structure of ultrasound	4.86 (0.57–41.57)	.149

4. Discussion

In recent years, continuous advancements in ultrasound technology have propelled its diagnostic accuracy to unprecedented heights. Its attributes, such as convenience, noninvasiveness, intuitiveness, repeatability, and dynamic imaging capabilities, have augmented its widespread utilization within prenatal diagnosis [24]. The fundamental nature of chromosomal abnormalities in disease lies in the impact on gene expression and function, resulting from alterations in the number or structure of chromosomes. This disruption affects numerous genes and gene groups, leading to an imbalance that hinders the differentiation and development of relevant organs within the human body. Consequently, this disturbance manifests as anomalies in both physical form and physiological function, ultimately giving rise to fetal malformations. Ultrasound’s capacity extends beyond detecting fetal structural abnormalities; it also enables the identification of subtle irregularities referred to as "soft marker abnormalities" [17,25,26]. These micro-structural fetal irregularities, often temporary and nonspecific, may diminish over the course of pregnancy. However, abnormal ultrasound soft marker findings have been associated with an elevated risk of fetal chromosomal anomalies and adverse prognoses [27]. In our study, the ultrasound abnormality index detection rate was 14.20% (2258/15,899), with a 6.75% (1872/15,899) incidence of soft marker abnormalities. The rate of chromosomal abnormality detection paralleled the aforementioned findings, reaching 2.40% (381/15,899). Among these anomalies, NT thickening emerged as the predominant ultrasound soft marker abnormality. Especially when the thickening of NT was higher than that of 3 mm, this was similar to the conclusion of Maya et al. [27] which points out that CMA examination should be carried out when NT thickened to 3 mm [28]. We also specifically analyzed the relationship between NT/NF thickening and the results of CMA, and found that when pregnant women were over 35 years old or accompanied by other ultrasound soft markers abnormalities, the detection rate of abnormal chromosomes could be significantly increased to 18.37% and 22.50%. This underscores the imperative for chromosome testing when NT thickening is detected during prenatal diagnosis. Additionally, various other ultrasound soft marker anomalies were also linked to chromosomal abnormalities, including nasal bone deficiency or incomplete ossification, lateral ventricular dilation, single umbilical artery, and renal pelvis dilation. Remarkably, our study showed that when the abnormal items of ultrasonographic soft markers reached two or more, the detection rate of abnormal chromosomes was higher than that of most single indicators. It is important to recognize the prevalence of detecting fetal ultrasound soft marker abnormalities during prenatal diagnosis, even though the necessity for chromosome examination in such cases remains contentious. Studies have demonstrated varying outcomes for certain soft marker abnormalities. For instance, severe lateral ventricular dilation was associated with a fetal death rate of 12.1%, and survivors exhibited a range of central nervous system outcomes [17]. The normal incidence of central nervous system of surviving fetuses was 42.2%, the proportion of mild/moderate nervous system developmental disorders was 18.6%, and the proportion of severe nervous system developmental disorders was 39.6%. Similarly, chromosomal abnormalities were detected in a proportion of fetuses with choroid plexus cysts [29]. However, divergent viewpoints exist, suggesting that chromosome testing might not be required for fetuses with choroid plexus cysts devoid of additional anomalies and when trisomy 21 screening outcomes are negative [30]. Hence, determining the necessity for chromosome testing based on ultrasound results necessitates a focus on abnormal soft marker findings alongside the presence of high-risk factors for fetal congenital malformations, culminating in a comprehensive assessment of testing necessity.

In addition, our study also pointed out that the probability of fetal chromosome abnormalities detected by ultrasound soft marker abnormalities and structural abnormalities is higher than that of simple ultrasound structural abnormalities. Ultrasound examination of fetal structural abnormalities mainly occurred in the cardiovascular system, nervous system abnormalities, maxillofacial, digestive system, and so on. In this study, the detection rate of chromosomal abnormalities in cardiovascular system was the highest among fetal structural abnormalities examined by ultrasound. Study has pointed out that when the fetus has cardiac abnormalities, the detection rate of chromosome abnormalities in 18-trisomy syndrome is the highest, and the detection rate of chromosomal abnormalities in fetuses with cardiac abnormalities with extracardiac abnormalities is significantly higher than that in simple cardiac abnormalities, which are 64.8% and 21.8% [31]. Therefore, when fetal ultrasound structure abnormalities, especially cardiovascular system abnormalities, accompanied by ultrasound soft marker abnormalities, pregnant women should be advised to actively carry out chromosome testing to rule out fetal chromosome abnormalities.

Furthermore, logistic regression analysis was employed to elucidate numerous factors associated with fetal chromosomal abnormalities in congenital malformations. The findings underscored that a multitude of factors were significant contributors to fetal chromosomal abnormalities, especially when the abnormal numbers of ultrasonographic soft markers was more than one, or the abnormal soft markers of ultrasound accompanied with abnormal structure of ultrasound. These findings echo those of previous studies, validating the associations between advanced maternal age, NIST anomalies, and parental chromosomal abnormalities with fetal chromosomal anomalies. Zhang et al. [31] studied the prenatal diagnosis indications and chromosome results of 13,795 fetuses and found that the detection rate of fetal chromosome structural abnormalities was higher in advanced age, NIST abnormalities, and chromosomal abnormalities in couples [32]. Zhu et al. [32] analyzed the correlation between pregnant women of different ages and fetal chromosome abnormalities by dividing pregnant women into different age groups according to their ages. The results showed that when the pregnant women were older than 37 years old, the detection rate of fetal chromosome abnormalities was significantly higher than that of pregnant women under 37 years old [33]. Trisomy 21 itself is a common chromosome abnormality, and trisomy 21 abnormality indicates that children are at risk of trisomy 21 [33,34]. In addition, we also use multivariable logistic to analyze the above factors. The results showed that when the pregnant woman was over 35 years old and more than two abnormal soft indexes were tested accompanied by one or more of the above high-risk factors, the chromosome abnormalities might be more likely to be detected. The results of these studies also indicate that when abnormal ultrasound findings occur in the prenatal diagnosis of pregnant women, especially when ultrasonographic structural abnormalities are combined with soft marker abnormalities, including the above-mentioned risk factors, the active development of chromosome testing might help to rule out fetal chromosome abnormalities. In addition, even if fetal abnormalities are screened out after 14 weeks of pregnancy, there are legislations that allow legal termination of advanced pregnancy, such as China [35]. Therefore, using ultrasonography in combination with CMA diagnosis allows for further diagnosis of fetal conditions to make more accurate clinical assessments.

There are certain limitations in this study. First, it should be noted that this study is based on a single-center retrospective analysis, which may introduce inherent bias. Additionally, our investigation primarily focuses on comparing the correlation between ultrasound and CMA results, as well as evaluating the clinical value of diagnosing chromosomal abnormalities; however, we did not extensively analyze the long-term follow-up persistence and prognosis of patients.

5. Conclusions

It becomes evident that when ultrasound assessments reveal the presence of two or more abnormal ultrasound soft markers, or when these soft marker anomalies co-occur with structural irregularities, a heightened propensity for detecting chromosomal abnormalities with associated fetal congenital malformations ensues. Additionally, it is noteworthy that a range of high-risk factors, encompassing advanced maternal age, a familial predisposition to congenital malformations, parental chromosomal anomalies, adverse pregnancy history, the identification of Trisomy 21 abnormalities, anomalous outcomes in NIST, have demonstrated a strong correlation with the likelihood of detecting chromosomal abnormalities. However, a small number of abnormal fetuses were included in the final CMA results of this study, and there was no statistical tracking of late pregnancy changes, which limited the correlation between ultrasound and chromosome abnormalities in this study. In the follow-up, we can consider to improve the experimental scheme and further use the prospective research method to carry out the research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Additional information

Funding

The Research project approval on the specialized alliance for women and children’s health in Nantong City (No. TFM202409).