This a special a special ultrasound scan (known as hysterosalpingo-contrast-sonography) during which a contrast medium is inserted in the uterus through the cervix and we can then see if the contrast medium fills the tubes and comes out at the other end.
It is a very well tolerated procedure and it will give a result straight away. It is very important to perform it during the first part of your cycle (before ovulation) to avoid displacing a potential pregnancy.