O desempenho da medida da translucência nucal na predição do desfecho gestacional

Abstract

Purpose: nuchal translucency (NT) is the sonographic appearance of the fluid accumulation in the posterior cervical region of the fetus, in the first trimester of pregnancy. It is used as an excellent method of screening for aneuploidy. In this study, we evaluate the association of NT measurement in exams performed at the institution with the occurrence of pregnancy outcomes. Objectives: To characterize the studied sample according with the maternal age, paternal age, gestational age and head length, buttocks of the fetus at the time of the examination. Examine the association between NT thickness measurement with the spontaneous termination of pregnancy; with the presence of chromosomal changes and malformation. Methods: A retrospective, descriptive and transversal study. 687 cases of singleton pregnancies were included, who performed ultrasonography with NT measure, with known outcome of pregnancy. Pregnancy outcomes were: miscarriage, fetal death, chromosomal abnormalitiesanmalformation. ROC (Receiver Operator Characteristic) curve was constructed to determine the performance of the test, define the value for the one that was verified the test sensitivity with false positive rate of 5% and performed logistic regression analysis for each of the possible outcomes studied. Results: 664 cases were normal and 23 showed an outcome.The gestational age ranged between 11 and 14.57 weeks and the CRL ranged from 45.2mm to 83.8mm. The mothers age ranged from 12 to 47 years. The paternal age ranged from 15 to 65 years. The NT thickness distribution showed an average of 1.617. In our sample, from the established cutoff point of 2.44 mm, it was verified that the NT measurement was excellent predictor of chromosomal alterations with AUC of 0.9961, and a sensitivity of 100% with a false positive rate of 5%. Abortions had low values ofNT, which was confirmed by the AUC 0.54 and sensitivity of 0%. Stillbirth sensitivity of 20%, with AUC of 0.7254.Regarding the association of NT thickness in the presence of malformation, it was found a good discriminatory ability of the test (AUC - 0.070), with a sensitivity of 57% for the cutoff of 2.4mm and an odds ratio of 6.017 in the sample. Conclusions: The measurement of NT thickness in the studied sample, had good association with the occurrence of fetal death and not associated with the occurrence of abortion. The association with the presence of chromosomal and morphological changes was excellent.