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ORIGINAL ARTICLE
Year : 2015  |  Volume : 28  |  Issue : 1  |  Page : 245-249

The value of nuchal translucency measurement as an early predictor of congenital fetal malformation


Department of Obstetrics and Gynecology, Faculty of Medicine, Menoufiya University, Menoufia, Egypt

Date of Submission28-Aug-2014
Date of Acceptance19-Oct-2014
Date of Web Publication29-Apr-2015

Correspondence Address:
Mahy Nabil Mahmoud Egiz
Department of Obstetrics and Gynecology, Faculty of Medicine, Menoufiya University, 2 Salah Abo Elkher Street, Shebien Elkom, Menoufia
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1110-2098.156002

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  Abstract 

Objective
The aim of the study was to estimate the value of the nuchal translucency (NT) measurement during the period from 10th to 14th week of gestation in predicting the possibility of congenital malformation in these fetuses.
Background
First-trimester screening is typically conducted between the 11th and 13th weeks 6 days of gestation. At this time, NT, free b-subunits of human chorionic gonadotropin (fB-hCG), and nasal bone are powerful markers for detection of fetal conditions.
Methods
The present study was carried out at the department of Obstetrics and Gynecology at Menoufyia University Hospital during the period between 2012 and 2014.
A total of 120 women were included in the study. The studied patients were divided into two groups.
Thorough history taking, full examination, routine laboratory investigations, hCG, and pregnancy-associated plasma protein A were taken. Ultrasound was performed to detect NT.
The collected data were organized, tabulated, and statistically analyzed using SPSS software computer package. For quantitative data, mean, minimum, maximum, and SD were calculated and comparison between two means was performed; for qualitative data, number and percent distribution were calculated and comparison between two groups was performed.
A normal value of NT is usually less than 2.5-3.0 mm in thickness; assessment of the biochemical markers and their correlation with malformed fetuses number was performed, and past history was taken from mother.
Results
The total number of women enrolled in the study was 120; four of 11 cases with congenital fetal malformation were with positive family history. NT in the affected fetuses with a mean 2.65 mm in the first group and 3.3 mm in the second group reflects a highly significant relationship. The cutoff point of NT is 2.55 mm with a sensitivity 73.6% and specificity 80.3%, whereas combined NT, B-hCG, and pregnancy-associated plasma protein A has 100% sensitivity and 35.8% specificity.
Conclusion
Prenatal screening has become now an integral part of obstetric care and raises the responsibility and awareness of neonatal care. Most women prefer to undergo screening first to find out whether the fetus's risk for birth defect is high.

Keywords: Congenital malformation, free beta subunit of human chorionic gonadotropin, nuchal translucency


How to cite this article:
Egiz MN, Abd El Hamid AN, Abd El Gayed AM, Dawood RM. The value of nuchal translucency measurement as an early predictor of congenital fetal malformation. Menoufia Med J 2015;28:245-9

How to cite this URL:
Egiz MN, Abd El Hamid AN, Abd El Gayed AM, Dawood RM. The value of nuchal translucency measurement as an early predictor of congenital fetal malformation. Menoufia Med J [serial online] 2015 [cited 2019 Sep 20];28:245-9. Available from: http://www.mmj.eg.net/text.asp?2015/28/1/245/156002


  Introduction Top


Prenatal screening is the systematic application of a noninvasive test to identify fetuses at risk for a disease or a condition before birth to warrant further invasive investigation or direct intervention action. Screening can only evaluate risk of a condition but it cannot determine 100% whether the fetus has such condition [1].

The international population risk of having a child with congenital abnormality, whether genetically and/or environmentally determined, varies between 3 and 5% [2].

First-trimester screening is typically conducted between the 11th and 13th weeks 6 days of gestation. At this time, nuchal translucency (NT), nasal bone (NB), and free b subunit of human chorionic gonadotropin (fB-hCG) are powerful markers for detection of many maternal and fetal conditions [3].

The association between fetal chromosomal abnormality and increased NT thickness during the first trimester of pregnancy is well established. Such a screening test may identify over 70% of trisomy 21 pregnancies in the first trimester, with a 5% screen positive rate [4].

In the 1990s, screening by a combination of maternal age and fetal NT thickness at 11-13+6 weeks of gestation was introduced. This method has now been shown to identify about 75% of affected fetuses with a false-positive rate of about 5% [5].

Dhaifalah et al. in their study confirmed that the use of a combination of maternal serum fB-hCG and pregnancy-associated plasma protein A (PAPP-A) with NT thickness at 11-14 weeks of gestation would identify about 90% of trisomy 21 pregnancies with a 5% false-positive rate [6].

The aim of this study was to estimate the value of the NT measurement during the period from 10th to 14th week of gestation in predicting the possibility of occurence of congenital malformation in these fetuses.


  Patients and methods Top


Patients

The present study was carried out at the department of Obstetrics and Gynecology at Menoufyia University Hospital during the period between 2012 and 2014.

A total of 120 women were included in the study. The studied patients were divided into two groups.

Group I included 100 pregnant women (gestational age ranging from 10 to 14 weeks) aged from 35 to 40 years without previous, past, or family history of congenital fetal malformation (CFMF).

Group II included 20 pregnant women (gestational age ranging from 10 to 14 weeks) with past or family history of CFMF regardless of their age.

Provision to maintain privacy

All the participants' names were hidden and replaced by code numbers to maintain privacy.

Inclusion criteria

Inclusion criteria were as follows: age group above 35 years in group 1, gestational age 10-14 weeks [as determined by last menstrual period and confirmed by the ultrasound (U/S) scan in the first trimester], a singleton pregnancy, and crown rump length (CRL) value between 45 and 84 mm.

Exclusion criteria

Exclusion criteria included multiple pregnancy and unexplained vaginal bleeding.

Methods

For every patient, the following were performed: informed consent from those who agreed to be included in the study. Thorough history taking with special emphasis on menstrual history for proper dating and obstetric history regarding obstetric formula. Full examination including general examination, abdominal examination, and local examination.

U/S

It was performed using mindray U/S machine 2200 plus, the abdominal probe.

NT is measured on a sagittal section through the fetus.

Technique

Use of the correct technique is essential:

  1. The fetus should be transverse (sagittal) in the imaging plane.
  2. The vertebral column should be facing the bottom of the screen.
  3. Fetal head should not be extended or flexed.
  4. Fetus should be floating free of the uterine wall (i.e. amniotic fluid should be seen between its back and the uterus).
  5. Only the lucency is measured (again differing from nuchal thickness).
  6. Ideally, only the head and upper thorax should be included in the measurement.
  7. The level of magnification should be appropriate (fetus should occupy most of the image), enabling 1 mm changes in measurement possible.
  8. The '+' calipers should be used for measurement.
  9. The widest part of the measurement should be taken.
  10. Also measurement of NB applicable in that position and measured in some cases.


Assessment

  1. Only values obtained when CRL values are between 45 and 84 mm are considered valid.
  2. The lucent region is generally not septated.
  3. Thickness rather than the appearance (morphology) is considered to be directly related to the incidence of chromosomal and other anomalies.
  4. A normal value is usually less than roughly 2.5 mm in thickness. However, it is maternal age dependent and needs to be matched to exact gestational age and CRL; if the value is more than 2.5 mm, we will look for abnormal levels of maternal serum a-fetoprotein, hCG, E3, and inhibin A as the results of all these factors may indicate a higher risk.


The NT cannot be adequately assessed if there is:

  1. Unfavorable fetal lie.
  2. Unfavorable gestational age.
  3. CRL less than 45 or greater than 84 mm.


Investigations

hCG and PAPP-A.

Statistical methods

The collected data were organized, tabulated, and statistically analyzed using SPSS software computer package. For quantitative data, mean, minimum, maximum, and SD were calculated and comparison between two means was performed; for qualitative data, number and percent distribution were calculated and comparison between two groups was performed.


  Results Top


The total number of pregnant women in the study, as shown in [Table 1], was 120. They were divided into two groups: the first group included 100 women (83.3%) aged between 35 and 40 years, whereas the second one included 20 women (16.7%) with history of CFMF whether in their offspring or in their families regardless of their age.
Table 1: Age and age groups according to outcome

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The outcome of CFMF in group 1 was offsprings and in group 2 one offspring. Of those with normal outcome, 74.4% were aged between 35 and 37 years, whereas 25.6% were aged from 37 to 40 years. In cases with malformed outcome, 30% were aged from 35 to 37 years, and 70% were aged from 37 to 40 years. This means that there was a highly significant correlation between malformed outcome and old age, whereas the mean age in the second group was 23.37 years with normal outcome and 19 years with malformed outcome; only one case in this group had malformed fetus [Table 1].{Table 1}

In group 1, 50% of those having neonates with CFMF were with positive consanguinity and also there was single positive case in the second group; this reflects that consanguinity is in highly significant correlation with CFMF.

In this study, four of 11 cases with CFMF were with positive family history, which represents 36.36% reflecting significant correlation.

A significant correlation was found between CFMF and previous abortions, as in this study, in the first group, 20% of those with malformed outcome had no history of abortion and 80% had history of abortion.

There was a highly significant correlation between CFMF and previous sibling with Down syndrome, as they represent 40% in the first group and 100% in the second group [Table 2].
Table 2: Previous down syndrome according to outcome

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In unaffected pregnancies, the median fB-hCG was 1.17 MoM (range 0.2-2.3) in the first group and 1.34 MoM (range 0.5-2.5) in the second group, and the median PAPP-A was 0.5 MoM (range 0.05-2.2) in group 1 and 0.47 MoM (range 0.08-2.1) in the second group. This shows significant correlation between CFMF and serum biomarkers [Table 3] and [Table 4].
Table 3: hCG according to outcome

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Table 4: PAPP-A according to outcome

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The study showed increased NT in the affected fetuses with a mean 2.65 mm (range 0.5-4.1) in the first group and 3.3 mm in the second group, which reflects a highly significant relationship [Table 5].
Table 5: NT according to outcome

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In all screened cases for NB, it was detected in 90% of those with malformed outcome in group 1 and 100% in group 2, giving a significant correlation.

The cutoff point of NT is 2.55 mm with a sensitivity 73.6% and specificity 80.3%; for B-hCG the cutoff point is 1.65 with a sensitivity 81.8% and specificity 78.0%; and for the PAPP-A it is 1.01 with a sensitivity 67% and specificity 70%. However, combined test of NT, B-hCG, and PAPP-A has 100% sensitivity and 35.8% specificity.


  Discussion Top


The mean age of the study population in the first group was 36.67 years with normal outcome and 38.30 years with malformed outcome, whereas in the second group the mean age was 23.37 years ranging from 18 to 28 years with normal outcome and 19 years with malformed outcome.

Gestational age in the study population ranged from 11 to 14 weeks in the first trimester. The mean gestational age was 12 weeks+3 days.

With improvement in the resolution of U/S machines and wide application of the NT scan for Down syndrome screening, it is possible to delineate normal fetal anatomy and to diagnose a wide range of fetal abnormalities in the first trimester [7].

In our study, positive consanguinity was detected in 15% of cases (18 cases); 14 (11.6%) cases were in the first group and 5 (4.1%) of them had CFMF, whereas the rest 4 (3.3%) were in the second group with only one case (0.8%) having CFMF. In a study conducted by Bahado-Singh and colleagues, they concluded that consanguineous marriages are common in the Eastern Mediterranean Region. The percentage of first-cousin marriages among all marriages has been reported to be 11.4% in Egypt and 30.2% in Kuwait [8].

The cutoff used in NT measurement was 2.55 mm and NT was increased in 5% (6/120); there were three cases with true positive results and one case with false results, and two cases aborted at 14 and 15 weeks gestation.

In a study conducted by Rozenberg et al. [9], they stated that the sensitivity of NT measurement is 60-77% with a 5% false-positive rate. Combining NT measurement with fB-hCG assay (first-trimester combined screening) increases the sensitivity up to 82%.

We evaluated fB-hCG values; 3/120 (2.5%) had decreased values below 0.5 MoM and in two cases they were associated with increased NT, and they had miscarriage in the first trimester. This is in agreement with the study by Spencer [10] who concluded that low maternal serum fB-hCG levels and increased fetal NT are associated, in the absence of an abnormal karyotype, with risk of impending fetal death.

Four cases (3.3%; 4/120) had elevated values of fB-hCG with no adverse pregnancy outcome. This is in agreement with the study by Brameld et al. [11] who found that high level of fB-hCG is of limited use as an indicator of adverse pregnancy outcome.

The study showed increased NT in three of the affected fetuses, which represents 2.5% (3/120). Bahado-Singh et al. [12] stated that NT was the first of the nonstructural markers to be identified. However, Locatelli et al. [13] stated that NT remains the single most predictive sonographic marker and showed strong prediction with trisomy 21 as an isolated marker.

Of the 120 cases, three cases (2.5%) had history of a baby with Down's Syndrome and 12 cases had history of babies with congenital anomalies (10%). The remaining 105 cases (87.5%) were without any history of Down's syndrome or any history of babies with congenital anomalies. However, 23 (19.1%) cases were with positive family history of CFMF; 12 (10%) of them were in the first group and 4 (3.3%) of them with CFMF, whereas 11 (9.1%) cases were in the second group, all with normal outcome.


  Conclusion Top


Because sonographic findings influence patient decision making, many high-risk patients wait the results from the second-trimester ultrasonography before deciding to undergo genetic amniocentesis. A low fB-hCG (<0.5 MoM) is associated with an increased frequency of adverse obstetrical outcomes and/or spontaneous abortion.

The combination of U/S and biochemical screening works better than either one alone. The first-trimester anatomic survey has varied significantly with respect to the populations screened, the gestational age at which the scan was performed, the use of transvaginal ultrasonography, the training and experience of the practitioner performing the scan, and the time allowed for the anatomic survey.

Recommendations

Sonography allows to identify many fetal anomalies since the first trimester but does not replace the midtrimester scan.

Combined test of NT, B-hCG, PAPP-A increases sensitivity up to 100%.


  Acknowledgements Top


Routine research support of Menofia University Hospitals for using the equipments of the hospital.

Mahy Nabil Mahmoud Egiz: corresponding author and editor of the work; Prof. Ahmed Nabil Abd El Hamid: main and final supervisor of the paper scientific content; Dr Alaa Masoud: secondary revision of the work and revising the collected data; Dr Ragab Dawood: primary revision of the work and revising the collected data.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Wald NJ, Huttly WJ, Rudincka AR Prenatal screening for Down syndrome: the problem of recurrent false-positives. Prenat Diagn 2004; 24 :389-389.  Back to cited text no. 1
    
2.
Bozzette M. Recent advances in prenatal screening and diagnosis of genetic disorders. AACN Clin issues 2002; 13 :501-510.  Back to cited text no. 2
    
3.
Cicero S, Bindra R, Rembouskos G. Integrated ultrasound and biochemical screening for trisomy 21 using fetal nuchal translucency, absent fetal nasal bone, free g-hCG and PAPP-A at 11 to 14 weeks. Prenat Diagn 2003; 23 : 306-310.  Back to cited text no. 3
    
4.
Nicolaides KH. Nuchal translucency and other first-trimester sonographic markers of chromosomal abnormalities. Am J Obstet Gynecol 2004; 191 :45-67.  Back to cited text no. 4
    
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Atzei A, Gajewska K, Huggon IC, Allan L, Nicolaides KH. Relationship between nuchal translucency thickness and prevalence of major cardiac defects in fetuses with normal karyotype. Obstet Gynecol Surv 2006; 61 :8-10.  Back to cited text no. 5
    
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Dugoff L. Ultrasound diagnosis of structural abnormalities in the first trimester. Prenat Diagn 2002; 22 :316-320.  Back to cited text no. 6
    
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Hafez M. Consanguineous matings in the Egyptian population. J Med Genet 2008; 20 :58-60.  Back to cited text no. 7
    
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Al-Awadi SA. Consanguinity among the Kuwaiti population. Clin Genet 2005; 27 :243-246.  Back to cited text no. 8
    
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Rozenberg P, Malagrida L, Cuckle H, Durand-Zaleski I, Nisand I, Audibert F. Down′s syndrome screening with nuchal translucency at 12(C0)-14(C0) weeks and maternal serum markers at 14(C1)-17(C0) weeks: a prospective study. Hum Reprod 2008; 17 :1093-1098.  Back to cited text no. 9
    
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Spencer, K. First trimester diagnosis and screening for fetal aneuploidy. Am J Med Genet 2007; 145 :18-32.  Back to cited text no. 10
    
11.
Brameld KJ, Dickinson JE, O′Leary P. First trimester predictors of adverse pregnancy outcomes. Office of Population Health Genomics, Department of Health, East Perth, Western Australia, Australia. Aust N Z J Obstet Gynaecol 2008; 48 :529-535.  Back to cited text no. 11
    
12.
Bahado-Singh RO, Oz UA, Kovanci E. Gestational age standardized nuchal thickness values for estimating mid-trimester Down′s syndrome risk. J Matern Fetal Med 2005; 8 :37-43.  Back to cited text no. 12
    
13.
Locatelli A, Piccoli MG, Vergani P. Critical appraisal of the use of nuchal fold thickness measurements for the prediction of Down syndrome. Am J Obstet Gynecol 2007; 18:192-197.  Back to cited text no. 13
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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