Detection of Other Birth Defects
The question that is often asked is whether other birth defects can be identified during the first-trimester ultrasound examination of the fetus? This section will discuss the ultrasound detection of birth defects, other than chromosomal anomalies and heart defects, that have been identified during the first-trimester and the outcome of fetuses with an increased nuchal translucency that is not explained by abnormal chromosomes or congenital heart defects.
Detection of Major Birth Defects During the First-Trimester Ultrasound Examination
In addition to heart abnormalities, investigators have evaluated the detection of other major birth defects when fetuses have been examined during the first-trimester of pregnancy. In a study reported by Carvalho et al in 2002, they evaluated their detection rate for birth defects in 2,853 patients who underwent first-trimester ultrasound screening, with the majority returning for examinations during the second (18 to 24 weeks) and third (30 to 34 weeks) trimesters of pregnancy. From this group of patients there were 130 fetuses with either major or minor birth defects. The following is a summary of their findings;
Of the 130 fetuses with birth defects, 22.3% (29/130) were identified during the first-trimester ultrasound, of which 9 were cardiac malformations. Of the remaining 81 birth defects not detected during the first-trimester ultrasound evaluation, 61.7% (50/81) of the remaining malformations were identified during the second-trimester study. The following lists the malformations not detected during the first-trimester examination that were present during the second-trimester evaluation. If you would like to review the genetic syndromes associated with these findings, click the name of the defect to review a list of genetic diseases associated with the specific malformation. Then click the RETURN or PREVIOUS PAGE button on your browser to return to this page.
Central Nervous System
Microcephaly
Retrognathia
Ventriculomegaly
Brain Atrophy
Dandy-Walker Syndrome
Cerebellar asymmetry
Encephalocele
Spina Bifida
Heart
Ventricular septal defect
Endocardial cushion defect
Hypoplastic Left Ventricle
Tetralogy of Fallot
Renal System
Hydronephrosis
Renal Agenesis
Multicystic Kidney
Renal Dysplasia
Abdominal Cavity
Intestinal Obstruction
Intraabdominal Cyst
Extremities
Clubbed feet
Clubbed hand
Clinodactyly
Overlapping FIngers
Polydactyly
Other
Ascites
Sacrococcygeal Teratoma
From the above list it is evident that a second-trimester ultrasound is mandatory to identify serious birth defects that may not be identified during the first-trimester examination. For this reason, Dr. DeVore recommends the Genetic Ultrasound as an option.
Birth Defects Associated with an Increased Nuchal Translucency and Normal Chromosomes
The incidence of congenital heart defects have been discussed in a previous section.
In a recent study reported by Maymon et al, they found that after abnormal chromosomes and congenital heart defects had been identified, the remaining fetuses with an abnormal nuchal translucency could be categorized into two groups.