The POP-Q (Pelvic Organ Prolapse Quantification) system uses nine standardized landmarks. A woman with a stage III anterior vaginal wall prolapse has Aa = +2 cm, Ba = +5 cm, C = –5 cm, D = –7 cm, Ap = –2 cm, Bp = –2 cm. What do the measurements Aa and Ba represent, and what does Ba = +5 indicate specifically?
- A Aa is the most distal point of the anterior vaginal wall relative to the hymen; Ba +5 means anterior vaginal wall prolapses 5 cm beyond the hymen
- B Aa is a fixed point on the anterior vaginal wall 3 cm proximal to the hymen; Ba is the most distal position of the remaining anterior vaginal wall above Aa; Ba +5 indicates the most dependent part of the anterior wall is 5 cm beyond the hymen ✓
- C Aa and Ba both measure the anterior fornix; Ba +5 indicates bladder descent of 5 cm
- D Aa is the anterior urethral meatus; Ba is the bladder neck; +5 indicates both are well beyond the hymen
Explanation
In the POP-Q system, Aa is a fixed point on the anterior vaginal wall located 3 cm proximal to the external urethral meatus (approximating the urethrovesical junction), with a range from –3 cm (normal, 3 cm inside hymen) to +3 cm (3 cm beyond hymen). Ba is the most distal (lowest) position of any part of the upper anterior vaginal wall between Aa and the anterior vaginal apex (C); it ranges from –3 to the value of C. A Ba of +5 indicates that the most dependent portion of the upper anterior vaginal wall (anterior vaginal bulge/cystocele) protrudes 5 cm beyond the hymenal plane, consistent with a large cystocele. Stage III prolapse = most distal prolapse point >1 cm beyond the hymen but not completely everted.
Reference: Shaw's Textbook of Gynaecology, 17th ed.
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Written and medically reviewed by the StethoPrep medical team.