Update on second trimester ultrasound scanning in pregnancy

Second trimester ultrasound is a standardised examination in pregnancy that should be routinely offered to all pregnant women, both for monitoring foetal growth and for screening for malformations. It should be performed between 18 and 24 weeks (in Spain from 18 + 0 to 22 + 0 weeks of gestation), by trained personnel and with appropriate equipment. The report should reflect foetal position and movements, biometry, amount of amniotic fluid, placental location and appearance, and foetal morphology. The foetal anatomy should include the study of the head (ossification and neurosonography), neck (discarding masses), thoracic cavity and its contents, abdomen and pelvis (studying stomach, umbilical vein, entrance of umbilical cord, kidneys, bladder), spine (in sagittal, coronal and axial planes), extremities (three segments, movement), and genitalia. Special attention should be paid to foetal heart examination (situs, four chamber view, left ventricular and right ventricular outflow-tracts, three-vessel and three-vessel-and trachea views). Neurosonography is also important with the transventricular, transcerebellar and transthalamic plane.