Ultrasound is the backbone of modern obstetric and gynecology practice. Recent technological breakthroughs in diagnostic ultrasound, including the advent of color Doppler, power Doppler, three-dimensional and four dimensional imaging, have led ultrasound to surpass the expectations of Ian Donald, its visionary father. The text is divided into three parts general aspects, obstetrics, and gynecology. The first and second textbooks were successful in this endeavor, but with the explosion of knowledge, it was clear that an expanded and updated third edition would be invaluable. Section one deals with a variety of topics that lay the foundation for the rest of the book. Section two addresses the myriad subtopics in obstetric ultrasound that optimize the care of pregnant women and fetal patients. The last section addresses the essential role that ultrasound plays in the many dimensions of clinical gynecology.