Female pelvic organ prolapse (FPOP) is one of the main diseases affecting the quality of life of middle aged and elderly women in non-neoplastic diseases. An aging population makes the incidence of this disease to increase year by year. Surgical operation is the main treatment. While the recurrence rate of classic repair surgery is high, the method of patch implantation reinforces the supporting force, which significantly reduce the recurrence rate. However, this method is costly and is associated with complications which may trigger new symptoms. As such, there is still no perfect surgical method. The main reason for this is that the assessment method of pelvic defects is crude and indirect, which results in the diagnosis of FPOP only representing external problems whereas, inner defected parts are not properly assessed. In recent years, research with the use of 2D and 3D MRI reconstructions on the anus levator muscle and ligament has become a hot topic. It found that the characteristic of the high resolution of soft tissue in the magnetic resonance imaging (MRI) has a big advantage in pelvic floor study.The investigators commenced the study of 3D reconstruction technology based on the MRI datasets in 2009. The investigators have mastered the most common, key technologies of MRI three-dimensional reconstruction. The investigators have done research targeted on the reconstruction methods of the normal pelvis, viscera, ligaments, pelvic floor muscles. This project is aimed at 3D reconstruction of the whole pelvic base on static and dynamic MRI images from FPOP patients, and establish the corresponding space coordinates assessment system to do location and quantitative research of the pelvic viscera and its support structure, thus providing a FPOP diagnosis platform that is more precise, direct and comprehensive.

Inclusion Criteria:

1. Female who were diagnosed with pelvic organ prolapse by using Pelvic Organ Prolapse Quantification (POP-Q) exams;
2. Without history of pelvic surgery;
3. Could cooperate smoothly with valsalva maneuver.

Exclusion Criteria:

1. Combined with gynecologic malignant tumors；
2. With MRI contraindications；
3. Female who refuse to undergo MRI evaluation.

This is a study comparing 60 cases (POP) to 20 controls (Non POP,with normal pelvic floor support) defined by using Pelvic Organ Prolapse Quantification (POP-Q) exams.All recruits will undergo the MRI evaluation,and the basic information of them will be recorded.