The lowest part of the peritoneal cavity in women is the rectum and the uterine sink, which is also the site of the peritoneal turnings. Abdominal lesions are most commonly caused by fluid accumulation due to infection, which can easily accumulate in this area or cavity, also known as the Douglas cavity, and the patient may experience distension and discomfort in the pelvic floor. If a secondary infection develops and a pelvic abscess is formed, the patient may also have a significant feeling of urgency and even fever, which can be further diagnosed by a puncture through the posterior vaginal vault. For patients with ectopic pregnancy who also have intra-abdominal bleeding, a posterior vaginal fornix puncture can be performed to obtain bloody fluid for reference and guidance in clinical treatment, and a caesarean section should be actively chosen. The lowest part of the female peritoneal cavity has certain anatomical and physiological significance for clinical treatment.