Located in a woman’s pelvic cavity, the fornix is a rounded crypt between a woman’s cervix and vagina, collectively referred to as the vaginal fornix. The fornix area is short for the female vaginal vault, an anatomical structure located within the female pelvic cavity. The fornix is a circular depression between the cervix and the vagina, which is divided into four parts according to its position: anterior, posterior, left, and right, among which the posterior fornix is the deepest, and is adjacent to the peritoneum, the vaginal wall, and the lowest pelvic cavity of the rectovaginal depression, which is clinically useful for puncture, drainage, or as a surgical access. The fornix is closely related to the diagnosis of female reproductive system diseases. Firstly, the posterior fornix is the deepest part of the vaginal fornix, which is often used as a puncture site to diagnose ectopic pregnancy or pelvic blood; secondly, the fornix is the most commonly used site for the administration of female intra-vaginal medication, and lastly, women should pay attention to avoiding fornix cracks caused by undue exertion in labor and delivery. The fornix is an important anatomical structure in the female body and is of great significance to the normal functioning of the female reproductive system. If you feel unwell, please go to a regular hospital as soon as possible, complete the relevant examinations and follow the doctor’s instructions for treatment, so as to avoid delaying the condition.