QUANTIFYING AND STAGING PROLAPSE

Historically, outcome measures for pelvic organ prolapse were single-organ instruments that required supplementation with diagnostic tests for accuracy and reproducibility. For example, the degrees of a cystocele could be staged using a standing-voiding cystourethrogram. To be accurate over time, these scales required repetition of the diagnostic tests to maintain the accuracy of the staging through the patient’s treatment and follow-up. More commonly, staging is done by physical examination alone, without the benefit of diagnostic tests. When physical examination of the patient with prolapse is done, the clinician can only speculate about which organs may be included in the prolapse in the descent of the anterior or posterior vaginal wall or the top of the vault. In this situation, the terms anterior vaginal wall prolapse and posterior vaginal wall prolapse are more appropriate than the terms cystocele or rectocele.

Researchers and clinicians recognized the need for a more comprehensive staging system that included all the pelvic organs. Although some of the older scales, such as the traditional four-stage classification system,² are still in limited use, the POP-Q is the most widely recognized internationally.³^–⁶

Pelvic Organ Prolapse Questionnaire

The POP-Q provides a descriptive and quantifying system for the relative position of the organs within the pelvis and enables objective staging of pelvic prolapse. The system, adapted from several classifications by Baden and Walker,⁷ was developed by the International Continence Society Committee on Standardisation of Terminology, Subcommittee on Pelvic Organ Prolapse and Pelvic Floor Dysfunction, in collaboration with the American Urogynecologic Society and the Society of Gynecologic Surgeons.¹ The POP-Q system arose from the efforts of the committee to develop a terminology standardization document. The original document was drafted in 1993 and refined in 1994. In 1994, it underwent a 1-year review and trial, during which time several minor revisions were made.

Reproducibility studies for the POP-Q were conducted in six centers in the United States and Europe, documenting interobserver and intraobserver reliability and clinical utility of the system in 240 women.⁸^–¹² Interobserver reliability was studied in 48 women with a mean age of 61 ± 14 years, parity of 3 ± 2, and weight of 74 ± 31 kg. Correlations for each of the nine measurements (r = 0.817, 0.895, 0.522, 0.767, 0.746, 0.747, 0.913, 0.514, and 0.488) were highly significant (P = 0.0008 to <0.0001). Staging and substaging were reported to be highly reproducible (tau_b = 0.702 and 0.652, respectively). In 69% of subjects, the stages identified were identical, and in the re-mainder, they did not vary by more than one stage among observers. Intraobserver reliability was studied in 25 women. Correlations (r) for the nine measurements were 0.780, 0.934, 0.765, 0.759, 0.859, 0.826, 0.812, 0.659, and 0.431. The position of the subject during measurement was found to affect staging, with upright examinations reflecting greater prolapse. Staging and substaging were reported to be highly reproducible (tau_b = 0.712 and 0.712, respectively). In 64% of subjects, the stages identified were identical, and in the remainder, they did not vary by more than one stage. All variation was increased in the upright position.¹² The standardization studies were done in the English language, and the standardization document was formally adopted by the International Continence Society in October 1995.

The Pelvic Organ Prolapse Questionnaire Descriptive System

The POP-Q descriptive system allows the clinician to quantify precisely a woman’s pelvic support without assigning a severity value; to make accurate, site-specific observations of the stability or progression of prolapse over time; and to accurately describe outcome of surgical repair. The system uses six reference points (Fig. 30-1) and a 3 × 3 grid (Fig. 30-2) for recording a quantitative description of pelvic organ support.

Figure 30-1 Six sites used for pelvic organ support quantitation (points Aa, Ba, C, D, Bp, and AP), genital hiatus (gh), perineal body (pb), and total vaginal length (tvl).

(From Bump RC, Mattiasson A, Bo K, et al: The standardization of terminology of female pelvic organ prolapse and pelvic floor dysfunction. Am J Obstet Gynecol 175:10-17, 1996.)

Figure 30-2 Three-by-three grid for recording a quantitative description of pelvic organ support.

(From Bump RC, Mattiasson A, Bo K, et al: The standardization of terminology of female pelvic organ prolapse and pelvic floor dysfunction. Am J Obstet Gynecol 175:10-17, 1996.)

The POP-Q descriptive system uses the hymen as the best available fixed point of reference that can be consistently and precisely identified. Six points—two on the anterior vaginal wall, two in the superior vagina, and two on the posterior vaginal wall—are located with reference to the plane of the hymen. The anatomic positions of the six points are recorded as centimeters above or proximal to the hymen (negative number) or centimeters below or distal to the hymen (positive number), with the plane of the hymen recorded as 0.

Points Aa and Ba are located on the anterior vaginal wall. Point Aa (range, −3 to 3 cm relative to the hymen) is located in the midline of the anterior vaginal wall 3 cm proximal to the external urethral meatus. This point corresponds to the approximate location of the urethrovesical crease, a landmark that is obliterated in many patients. Point Ba (−3 cm in the absence of prolapse) represents the most distal or dependent position of any part of the upper anterior vaginal wall from the vaginal cuff or anterior vaginal fornix to point Aa. In women with total post-hysterectomy vaginal eversion, point Ba has a positive value equal to the position of the cuff.

Two points on the superior vagina represent the most proximal locations of the lower reproductive tract in a normal position. Point C represents the most distal or dependent edge of the cervix or the leading edge of the vaginal wall cuff (i.e., hysterectomy scar) after total hysterectomy. Point D represents the location of the posterior fornix or pouch of Douglas in a woman who still has a cervix and the level of uterosacral ligament attachment to the proximal posterior cervix. It is helpful in differentiating suspensory failure of the uterosacral–cardinal ligament complex from cervical elongation (symmetric or eccentric), in which the location of point C is significantly more positive than the location of point D. Point D is omitted in the absence of the cervix.

There are two points on the posterior vaginal wall. Point Bp (−4 cm in the absence of prolapse) represents the most distal or dependent position of any part of the upper posterior vaginal wall from the vaginal cuff or posterior vaginal fornix to point Ap. In a woman with total post-hysterectomy vaginal eversion, point Bp has a positive value equal to the position of the cuff. Point Ap (−3 to 3 cm relative to the hymen) is located in the midline of the posterior vaginal wall 3 cm proximal to the hymen.

The numbers in the descriptive system can be recorded in the grid or, more commonly, as a series of numbers (e.g., −2, −2, −6, −7, −3, −3, 10, 3, 2), which represents clinical findings for the six vaginal points relative to the hymen and the total vaginal length (tvl), genital hiatus, and perineal body. The position of the patient during measurement should be documented, because the upright position potentially increases the stage of the descent.