A scan for a lack of periods usually consists of two different scans: the abdominal scan gives a good overview, but for most gynaecological ultrasounds we prefer to perform a vaginal ultrasound, where a narrow probe is inserted. A vaginal ultrasound may sound awkward, but it is generally a far gentler examination than a cervical smear. Although the vaginal ultrasound is done after bladder emptying, if you are attending QDOS for the first time, or re-visiting after a few years, we prefer to begin with abdominal pictures. Water in the bladder makes the abdominal scan clearer, so it helps if you have had two glasses of any liquid to drink before your appointment. If you have visited for a vaginal ultrasound before, you may have been advised not to worry about bladder filling for your next appointment.