The document discusses pelvic organ prolapse and its classification using the POP-Q system. The POP-Q system divides prolapse into 5 stages based on the position of various vaginal landmarks relative to the hymen. Stage 0 means no prolapse, while stage 1 is mild with the most distal portion of the prolapse within 1 cm of the hymen. Stages get progressively worse up to stage 4 where the entire lower genital tract is everted outside the vaginal opening. Positive numbers indicate points outside the vagina, while negative numbers are within.