Committee Opinion No. 418: The Complete 11-14 Week Prenatal Sonographic Examination.

OBJECTIVE

Sonography during the first trimester provides an opportunity to assess a pregnancy in its early stage. This document provides an opinion about the implementation and content of prenatal sonographic examinations at 11-14 weeks gestation in Canada.

TARGET POPULATION: Pregnant women at 11-14 weeks gestation.

BENEFITS, HARMS, AND COSTS: The 11-14 week prenatal sonographic examination can provide important information that may contribute to pregnancy management. It can be used to confirm viability, establish gestational age, determine the number of fetuses, assess the adnexa/ovaries, and, in a multiple pregnancy, assess chorionicity and amnionicity. Scanning also offers an opportunity to detect fetal abnormalities and perform aneuploidy screening by measuring the nuchal translucency thickness. It may be valuable in screening for preeclampsia and other obstetrical disorders (by combining uterine artery Doppler scanning with other bio-clinical markers) and for invasive placentation. There are no physical harms to mother or fetus from offering a routine 11-14 week prenatal sonographic examination, and there are no extra costs for patients.

EVIDENCE: Articles related to routine 11-14 week prenatal sonography were identified in a search of EMBASE and MEDLINE using the search terms first trimester ultrasound, nuchal translucency, and 11-14 week ultrasound. The search included all articles published on the topic until May 2019. Abstracts were reviewed by one author, and articles deemed relevant were then reviewed in full to determine whether to include them in the study. Articles that were not in English and articles that did not pertain to 11-14 week prenatal sonography were excluded.

INTENDED AUDIENCE: This document is intended for sonographers, midwives, family physicians, obstetricians, and maternal-fetal medicine specialists.