[A proposed protocol for obstetrical ultrasound examination]

Ultrasound has a number of valuable functions in obstetrics including dating, confirming viability, counting the number of fetuses and the exclusion of gross fetal anomalies. During two routine obstetric ultrasound scans, between 11 and 14 gestational weeks and around 20 weeks, the fetus should be carefully examined after which the existence of anomalies can be confirmed or, with a limited certainty that ultrasound enables, excluded. In order to obtain high standards of ultrasound screening, a uniformed protocol is needed, which would enable standardized examination. In this paper the Novi Sad University Department of Obstetrics and Gynaecology presents a new protocol for ultrasound examination which would ensure standardized ultrasound scanning and adequate record keeping.

The protocol is based on contemporary recommendations of the Royal College of Obstetricians and Gynaecologists of Great Britain, the Royal College of Radiologists of Great Britain, the American College of Obstetricians and Gynaecologists, as well as protocols used in routine ultrasound examinations of low-risk population (1,2,3,4,5,6).

There are two protocols: one for scanning in the first and the other in the second/third trimester. All the findings are recorded in adequate forms. In the first trimester number, viability, gestational age and expected date of delivery are established (4,6). At the end of the first trimester an anomaly scan can be performed as well (8,9,10,11,12). It includes measuring of crown-rump length, nuchal translucency and fetal heart rate, and examination of placenta, skull, brain, spine, abdomen, stomach, bladder and upper and lower extremities. An adjusted risk of chromosomal abnormality is given, based on maternal age and nuchal translucency measurement. In the second and third trimester the usual fetal biometry is performed as well as a detailed scan of anatomy, which includes searching for ultrasound markers of chromosomal abnormality. At 23 weeks the transvaginal evaluation of cervical length is performed, in an attempt to screen for women at risk of preterm delivery. A new, adjusted risk of chromosomal risk can be given, based on maternal age, nuchal translucency measurement in the first trimester and presence/absence of ultrasound markers of chromosomal abnormality.

Ultrasound in obstetrics has a major role. All scans in pregnancy must have clear aims, which in early pregnancy are (2): establishing fetal viability; establishing gestational age; identification of multiple pregnancies and their horionicity; exclusion of major fetal anomalies; psychological support and in second trimester are (4,13): (1) establishing normal ultrasound appearances of the fetus, which does not mean that the fetus is normal. The expression 'normal' should be avoided because of possible medico-legal implications. (2) identification of: anomalies incompatible with life; anomalies linked with high morbidity and long-term handicap; fetal conditions than that can be treated during intrauterine life; fetal conditions that will need postnatal tests and therapy.

New protocol and forms will enable an easier systematic obstetric ultrasound examination.