RESUMO
OBJECTIVE: To establish the normal reference range of fetal nasal bone length (NBL) during the second trimester in an Afro-Caribbean population and the likelihood ratio (LR) for fetal trisomy 21. METHODS: Prenatal records of euploid, non-malformed singleton fetuses who underwent second-trimester ultrasonographic scans at 20-24 weeks of gestation were retrospectively analyzed for NBL and gestational age (GA). Only Afro-Caribbean couples were selected. The relationship between fetal NBL and GA was determined. The data of all fetuses with Down syndrome were provided by the French West Indies Register of Congenital Malformations (REMALAN). RESULTS: There was a significant linear association between fetal NBL and GA (R2 = 0. 354). The 50th percentile for NBL increased from 5.0 to 7.0 mm from week 20 to 24 of gestation. The nasal bone (NB) was absent or hypoplastic in 8.6% of the euploid fetuses and in 69.2% of the trisomy 21 fetuses. The LR for trisomy 21 of absent or hypoplastic NB in an Afro-Caribbean population was 8.02, but only 2.32 when this sign was isolated. CONCLUSION: The reference range for fetal NBL at 20-24 weeks of gestation in an Afro-Caribbean population and the LR for trisomy 21 of absent or hypoplastic NB differed from the other populations.
Assuntos
Síndrome de Down/diagnóstico por imagem , Osso Nasal/diagnóstico por imagem , Feminino , Idade Gestacional , Humanos , Martinica , Gravidez , Segundo Trimestre da Gravidez , Valores de Referência , Estudos Retrospectivos , Ultrassonografia Pré-NatalRESUMO
OBJECTIVE: To establish a structured review process to facilitate the identification of the fetal nasal bone (NB) in the first trimester ultrasound scan to improve the quality images. METHODS: We conducted a retrospective observational study in fetal NB images obtained during ultrasound exams of singleton pregnancies that underwent first trimester screening (crown-rump length 45-84 mm). When the images were obtained the examiner was not aware of the study. Audit was conducted by an examiner according criteria established by the Fetal Medicine Foundation. Fetal NB images were assessed regarding adequate magnification, mid-sagittal view and transducer held parallel to the direction of the nose. The transvaginal and transabdominal as well as anterior and posterior fetal back groups were compared using χ(2) test. RESULTS: We considered 874 fetal NB images for auditing. Fetal NB was considered present in 865 images (99%). During the audit process, we identified 72 (8.2%) cases of disagreement between examiner and auditor assessments. Disagreement was higher when image quality was poor (62 cases = 7%). Transvaginal approach performed better in the following criteria: adequate magnification (p < 0.001), midline (p < 0.001) and completely adequate (p < 0.001). CONCLUSION: A peer reviewed audit program for fetal NB is feasible in a clinical scenario. Image quality appears to play an important role in compliance to image standards audited and in agreement between examiner and auditor.