Prenatal diagnosis of congenital dislocated spine and complex heterotaxy syndrome with 3D ultrasound and helical computed tomography.

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Congenital spinal dislocation is rare, with only one reported prenatally diagnosed case, published in 20031. This abnormality is characterized by an anterior defect in the formation of the vertebrae with vertebral displacement and neural canal angulations. An early, embryonic mechanism is the origin of this spinal abnormality2. Prenatal diagnosis is important for parental counseling regarding neurological damage and postnatal management3, 4. We report a case of a fetus with vertebromedullary abnormalities related to L1 dislocation associated with complex heterotaxy, evaluated prenatally using complementary imaging: three-dimensional (3D) ultrasound and helical computed tomography (CT). A 25-year-old woman, gravida 2, para 1, with unremarkable history and without consanguinity, wasreferred to the prenatal center at 22 weeks of gestation for fetal lumbar vertebromedullary abnormalities associated with complex heart disease. She had a previous child who required orthopedic treatment for metatarsus varus. The risk for trisomy on first-trimester combined screening was 1/6320 (nuchal translucency, 1.6 mm; craniocaudal length, 57 mm; free β-human chorionic gonadotropin, 1.40 multiples of the median (MoM); pregnancy-associated plasma protein-A, 0.92 MoM). No abnormality was detected at this first scan. Examination of the heart at 22 weeks of gestation showed dextrocardia associated with atrial inversion, atrioventricular and ventriculoarterial concordance, probable pulmonary valve stenosis, persistent left superior vena cava (dilated coronary sinus) and interrupted inferior vena cava with azygos continuation. A persistent right intrahepatic umbilical vein was described with normal flow in the ductus venosus. The gallbladder was situated on the left side of the umbilical vein. On two-dimensional ultrasound performed at 22 weeks of gestation, we suspected two hemivertebrae in L1 and L2 and detected a low-attached spinal cord and bilateral clubfeet. Amniocentesis was performed at 22.2 weeks of gestation and revealed a normal male karyotype (46XY). No pathogenic copy-number variation was detected by array comparative genomic hybridization (custom 60K Agilent array with a median resolution of 400 kb (Agilent Technologies, Inc., Santa Clara, CA, USA)). The patient opted for helical CT at 29 weeks, despite the radiation, since she had made the decision to terminate the pregnancy, owing to the severe anomalies. Fetal 3D ultrasound and helical CT demonstrated congenital dislocation of the thoracolumbar spine with an abnormal aspect of L1 with agenesis of the vertebral body and location behind T12 (Figure 1). After multidisciplinary consultation for parental counseling, termination of pregnancy was accepted because of the unfavorable prognosis. Pathological examination confirmed a rupture of the thoracolumbar hinge with withdrawal of the anterior lumbar vertebral wall (Figure 2), and complete heterotaxy syndrome with left isomerism. In this case, the abnormal appearance of the spine detected by ultrasound could be defined precisely using complementary imaging: ultrasound with 3D reconstruction and helical CT. The contribution of these two complementary imaging modalities, compared with two-dimensional ultrasound, allowed an accurate representation of this rare and difficult-to-diagnose anomaly. This spinal abnormality associated with fetal heterotaxy syndrome has not been described previously in the literature. Nevertheless, spinal malformations are often associated with other abnormalities5.