There are two small pouches close to the uterus, one on either side, called the cul-de-sacs. The anterior cul-de-sac is located between the bladder and the uterus. The posterior cul-de-sac is found between the uterus and the rectum. They are also called the excavatio recto-uterina (posterior) and excavatio vesico-uterina (anterior). Refer to the accompanying photo to see exactly where they are located.
In women undergoing fertility treatment, fluid in the cul-de-sac (as seen on ultrasound) is a common finding in ovarian hyperstimulation syndrome (OHSS). If the doctor suspects that you have this condition, he or she will likely suggest that you have an ultrasound to check for fluid in the cul-de-sac and measure your ovaries (enlarged ovaries are also common in OHSS).