A case report of prenatally diagnosed tetrasomy 18p
A 28-year-old primi gravid woman was referred to our fetal treatment center because of suspected fetal congenital heart disease at 32+4 weeks of gestation. The ultrasonography showed asymmetric intrauterine growth retardation (IUGR) with 5-week smaller abdominal circumference. The fetal echocardiography demonstrated dextrocardia with cardiomegaly (cardio-thoracic ratio, 0.64), mild pericardial effusion, and decreased left ventricular function (modified myocardial performance index, 0.68). There was no intracardiac abnormality. Doppler findings in the middle cerebral artery revealed increased peak systolic velocity (71 cm/sec, 1.3-1.5 MoM), which suggested fetal anemia. Imperforate anus was also suspected. The cordocentesis was performed at 33+2 weeks of gestation for identifying the karyotype, hemoglobin, and the presence of viral infection. The karyotyping confirmed tetrasomy 18p by G-banding and fluorescence in situ hybridization (). Fetal hemoglobin level was 9.7 g/dL and there was no evidence of viral infection such as toxoplasma, rubella, cytomegalovirus, and herpes simplex virus.\nThe male infant was delivered at 36+6 weeks of gestation; weighing 2,256 g, which was below 10 percentile. Apgar score was 6, 8 at 1, 5 minutes, respectively. Because of low oxygen saturation (76%), the baby was admitted to the neonatal intensive care unit. Initial hemoglobin level was 11.4 g/dL, and after transfusion of packed red blood cells, his oxygen saturation got over 97% without applying oxygen. Low-set ears with small auricles were shown () and muscle tone was increased. The postnatal echocardiography and cardiac computerized tomography revealed dextrocardia and mild cardiomegaly without pericardial effusion, and the cardiac function was within normal range. As prenatally suspected, the baby had a low type of imperforate anus, and underwent anoplasty. Swallowing difficulty was also found and after feeding rehabilitation therapy, the baby could be fed. There were no other abnormalities on further evaluations.\nAt the age of 3 months, the brainstem auditory evoked potentials and auditory brainstem response revealed right sensorineural hearing loss due to the peripheral conduction defect. The follow-up echocardiography still showed dextrocardia without cardiomegaly. The baby was scheduled for the developmental test.