Transvaginal ultrasounds showing an ectopic pregnancy (left) and a normal intrauterine pregnancy (right).  In the image on the left, the uterus is empty, and there is a fetus located in the pelvis (arrow).  In the image on the right, a fetus is seen developing within the body of the uterus, surrounded by amniotic fluid (black). (Courtesy of Dr. N. Jaffer)