OBJECTIVE:

To evaluate the diagnostic performance of first trimester ultrasound in the identification of structural defects that are detectable and potentially detectable at this stage of gestation.

MATERIALS AND METHODS:

Transversal and descriptive study carried out at the Maternal-Fetal Medicine Department of the Instituto Nacional de Perinatología Isidro Espinosa de los Reyes between March 2017 and October 2018. Inclusion criteria: Patients who attended the first trimester screening ultrasound and underwent early fetal anatomical evaluation. A diagnostic test-type study with calculation of diagnostic indices was performed.

RESULTS:

1652 first-trimester ultrasounds were found in which the prevalence of structural defects was 2%. Due to circumstances beyond the research, the gold standard could only be applied to 1610 patients from whom a detection rate of 83.62% of structural alterations and 100% specificity was obtained with the first-trimester ultrasound.

CONCLUSION:

The first-trimester ultrasound is ideal for performing the first fetal anatomical evaluation, with high acceptance among patients and physicians. This study does not replace but rather complements the fetal morphological assessment carried out in the second trimester; by combining both assessments the sensitivity is over 90% for detecting structural alterations.

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