Chapter 5 - Ultrasound and early pregnancy

Summary

Ultrasound is an integral part of early pregnancy assessment. This chapter covers the normal findings in early pregnancy, the ultrasound diagnosis of early pregnancy failure, and the spectrum of appearances of perigestational hemorrhage. It discusses the first-trimester evaluation of chorionicity and amnionicity in multiple gestations. Chorionicity is the most important prognostic indicator in multiple gestations therefore it is vital to make an accurate determination of this any time a multiple pregnancy is seen. Monochorionic diamniotic twins are at risk for specific complications such as twin-twin transfusion syndrome; this makes the prognosis worse than for dichorionic twins. Knowledge of the normal imaging findings and expected developmental milestones is vital for accurate interpretation. Recognition of monochorionic pregnancies and significant anomalies allows for appropriate early referral for specialist evaluation. Ultrasound is the most accurate way to triage patients with pain and/or bleeding in the first trimester.