An internal scan allows better visualisation of the womb and its contents. This is because the soundwaves do not have to travel far because the tip of the probe is inserted very close to the womb and gives a much better picture than an abdominal (transabdominal) scan. With this approach, the soundwaves have to travel through your tummy wall and occasionally the images obtained are not clear enough to make a definitive diagnosis. Thus, in very early pregnancy, in overweight women or when the womb is tilted backwards, or when a clear diagnosis cannot be reached with a transabdominal scan, a transvaginal approach might be necessary.