What are the levels of uterine support described by DeLancey's system?

DeLancey's Three Levels of Uterine and Vaginal Support

DeLancey's system describes three distinct anatomical levels of pelvic support, each with unique structural characteristics and functional roles in maintaining vaginal and uterine position.

Level I: Apical Suspension (Upper Third of Vagina)

• The upper third of the vagina is suspended vertically from the pelvic sidewalls by the paracolpium, which is a continuation of the cardinal ligament 1.
• The uterosacral ligament serves as the main apical fixation structure, providing suspension in the sacral direction 2.
• These vertical fibers of the paracolpium are critical in preventing vaginal apex prolapse and vaginal eversion after hysterectomy 1.
• The cardinal ligament at this level is primarily composed of vascular systems, lymph vessels, and loose connective tissue around them, rather than tough connective tissue structures 2.
• MRI imaging of Level I defects shows a characteristic "chevron sign" when bilateral fascial defects are present 3.

Level II: Lateral Attachment (Middle Third of Vagina)

• The middle third of the vagina attaches laterally to the arcus tendineus fasciae pelvis (ATFP) and the fascia of the levator ani muscles through the paracolpium 1.
• The ATFP is the edge of the superior fascia of the pelvic diaphragm, bounded by the obturator fascia, with a smooth surface close to the levator ani muscle 2.
• This level provides lateral support rather than vertical suspension 1.
• Contrary to earlier assumptions, there are no strong ligamentous structures connecting directly to the ATFP at the lateral vaginal wall 2.
• The ATFP fuses with the vaginal fascia in approximately the middle to lower one-third segments of the vagina 2.
• MRI imaging of Level II defects demonstrates the "saddlebags sign" when bilateral paravaginal defects are present 3.

Level III: Distal Fusion (Lower Third of Vagina)

• The lower third of the vagina fuses directly with the perineal membrane, levator ani muscles, and perineal body 1.
• This level represents direct fusion rather than suspension or lateral attachment 1.
• Dense connective structures fix the bilateral angles of the bladder triangle, starting from the cervix and vagina and ending in the bladder muscle wall 2.
• MRI imaging of Level III defects shows the "mustache sign" when bilateral fascial defects are present 3.

Clinical Significance

• The three-level system can be conceptualized as forming a "double hammock" structure of fascial ligament support above the levator ani muscle, with two parallel planes providing comprehensive pelvic organ support 2.
• Level I vertical suspension is the critical differentiating factor between vaginal eversion (where apical support fails) and isolated cystocele-rectocele where the vaginal apex remains well-suspended 1.
• Surgical interventions target specific levels based on the site of support failure, with Level II representing the upper border where certain suspension procedures are performed 4.