Trisomy 21 - mild phenotype

Frantisek Grochal, MD

Femicare, s.r.o., Center of prenatal ultrasonographic diagnostics, Martin, Slovak republic. UVN SNP Ruzomberok, Gynecological and obstetrical department. Catholic University in Ruzomberok, Faculty of Health Care, Ruzomberok, Slovak Republic.

Case report

A 21 year-old woman (G1P0) from a nonconsanguineous couple, first time visited our center at 18+3 weeks of her pregnancy with positive biochemical screening for Down syndrome. Our ultrasound examination revealed a few markers of chromosomal anomalies, including absent nasal bone, prenasal edema, echogenic intracardiac focus, and shortening of long bones (femur, humerus). Consequent amniocentesis confirmed the diagnosis of Down syndrome. The parents opted for the continuation of the pregnancy and the mother was scanned again at 29+3 weeks of her pregnancy. During our scanning we made several 3D images of the fetus, revealing no abnormality, although in 2D scans hypoplastic nasal bone and prenasal edema was still clearly visible. The case is an example when 3D imagination can make certain disservice in searching for facial dysmorphology. Actually the face of the fetus looked normal and nice. The baby was born at 40 weeks with only mild features of the Down syndrome. 

Here are some images and videos that we took during our exams.

Images 1, 2, 3, 4, 5 and video 1: 29+3 weeks of pregnancy; the images and video show 3D visualization of mildly stigmatized fetus with Down syndrome. The case is an example where 3D imaging made a disservice regarding searching for facial dysmorphology, because the face actually looked normal and cute, although 2D imaging (see 2D images below - images 6, 7) showed hypoplastic nasal bone and prenasal edema.

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Images 6, 7: 18+3 weeks (image 6) and 29+3 weeks (image 7) of pregnancy; the images show sagittal 2D scans of fetal face with absent (hypoplastic) nasal bone and prenasal edema.

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Images 6, 7: 18+3 weeks (image 6) and 29+3 weeks (image 7) of pregnancy; the images show 4-chamber view of the fetal heart - a hyperechoic focus was present within the left ventricle at 18+3 weeks, but was not visible at 29+3 weeks. The heart was structurally normal.

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Images 8, 9: 18+3 weeks of pregnancy; the images show shortened long bones of the fetus (femur - FL in image 8, and humerus - HL in image 9).

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