title: How effective is ultrasound-based screening for trisomy 18 without the addition of biochemistry at the time of late first trimester?
abstract: Trisomy 18 (T18) remains the second most common aneuploidy. It is associated with multiple congenital anomalies and causes intrauterine fetal demise in the most severe cases.
  
  
  OBJECTIVE
  To examine the screening performance of ultrasound-based protocols for detecting T18, we aimed to determine the most common signs and their prevalence in fetuses with T18 to develop logistic regression model.
  
  
  METHODS
  This was a prospective study based on singleton pregnancies examined at gestation 11+0 to 13+6. The referrals constituted 6210 patients. Scan protocol enclosed a systematic review of the entire early fetal anatomy, including fetal cardiac evaluation and sonographic signs of aneuploidy.
  
  
  RESULTS
  Our study population comprised 5650 pregnancies: 5613 cases with a normal karyotype and 37 cases with T18. The mean nuchal translucency (NT) thickness in the subgroup of euploidy was 1.7 and in the subgroup of T18 it was 5.4. No statistically significant differences were found in terms of maternal age. One case of T18 (2.7%) demonstrated no markers of aneuploidy as opposed to 5111 cases of euploidy (91.1%). Extracardiac malformations were identified in 13 cases of T18 (35.1%) and in 48 cases of euploidy (0.8%). Congenital heart defects were observed in 26 cases of T18 (70.3%) and in 27 cases of euploidy (0.5%).
  
  
  CONCLUSIONS
  Our results showed good screening performance of ultrasound-based risk calculation models. When the first trimester pattern of T18 is considered, an increased NT, tricuspid regurgitation, single umbilical artery, omphalocele and right dominant heart should be specifically searched for.
authors: Marcin
authors: M
authors: Wiechec
authors: Anna
authors: A
authors: Knafel
authors: Agnieszka
authors: A
authors: Nocun
authors: Anna
authors: A
authors: Matyszkiewicz
authors: Ewa
authors: E
authors: Wiercinska
authors: Emilia
authors: E
authors: Latała
mesh_terms: D000015:Abnormalities, Multiple / Q000000981:diagnostic imaging; D000293:Adolescent; D000328:Adult; D002887:Chromosomes, Human, Pair 18; D018618:Echocardiography, Doppler, Color; D005260:Female; D005865:Gestational Age; D006330:Heart Defects, Congenital / Q000000981:diagnostic imaging; D006801:Humans; D016015:Logistic Models; D008423:Maternal Age; D062145:Maternal Serum Screening Tests; D008875:Middle Aged; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011296:Prenatal Diagnosis / Q000379:methods; D011446:Prospective Studies; D014314:Trisomy; D000073842:Trisomy 18 Syndrome; D016216:Ultrasonography, Prenatal; D055815:Young Adult