Background. Bedside sonography performed by emergency physicians is frequently utilized for real-time clinical decision-making in the emergency department (ED) setting. This includes the sonographic evaluation of pain or bleeding in the first trimester of pregnancy. The detection of intrauterine pregnancy (IUP) or life-threatening conditions, including ectopic pregnancy, is critical. Objectives. This paper will review several important pearls and avoidable pitfalls of this diagnostic modality by brief presentation of illustrative cases followed by discussion of key principles. Case Reports. Three patients evaluated in the ED for bleeding or pain occurring during the first trimester of pregnancy will be presented. Conclusions. When conducting emergency bedside ultrasound for the evaluation of first trimester pregnancy, it is important to avoid common pitfalls that can place your patient at risk.