Analysis of differences in Pelvic Organ Prolapse Quantification scores at different anatomical sites before and after anesthesia for guiding surgical planning in female patients with pelvic organ prolapse

Abstract

Objective

This study aimed to analyze the differences in Pelvic Organ Prolapse Quantitation (POP-Q) scores before and after anesthesia in patients with pelvic organ prolapse at different sites and explore the influence of POP-Q scores on surgical decision making.

Methods

A prospective observational study was conducted involving 60 female patients with pelvic organ prolapse who underwent surgical treatment at the Chongqing Health Center for Women and Children between January 2023 and June 2023. The cohort included 26 patients with uterine prolapse and 34 patients with cystocele. POP-Q scores and other relevant data were compared under two conditions: before anesthesia (with Valsalva maneuver) and after anesthesia (with cervical traction).

Results

There were no statistical differences in the mean age, menopausal status, mean body mass index, mean number of pregnancies, or related primary diseases between the two groups (p>0.05). The minimum tractive force required for cervical traction after anesthesia was 4.81 N. In both groups, the POP-Q scores for points C, D, and Bp were significantly higher after anesthesia than before anesthesia (p<0.05). In the uterine prolapse group, there were no significant changes in the scores for points Aa, Ba, and Ap before and after anesthesia (p>0.05). However, in the cystocele group, the score for point Aa decreased significantly after anesthesia compared to before anesthesia (p=0.016).

Conclusion

The increased scores of points C, D, and Bp after anesthesia suggest that the evaluations of uterine prolapse should be based on post-anesthesia measurements. Conversely, evaluations of cystocele should rely on pre-anesthesia measurements due to the decrease in point Aa scores observed after anesthesia.

1. Introduction

Pelvic organ prolapse (POP) refers to the downward displacement of pelvic organs, including the uterus, bladder, and rectum, leading to abnormal positioning and impaired function of these organs [1]. POP is frequently associated with urinary incontinence, fecal incontinence, perineal bulging, and other symptoms, significantly impacting women's quality of life [2].

The Pelvic Organ Prolapse Quantitation (POP-Q) system provides a standardized method for quantifying the extent of prolapse, serving as an objective criterion for evaluating POP [[3], [4], [5]]. The accuracy of POP-Q measurements directly influences the choice of surgical protocols and the success rate of surgery [6]. Traditionally, patients are placed in the lithotomy position, and the most severe degree of prolapse is assessed under the Valsalva maneuver [7]. This approach may be influenced by factors such as patient fatigue, improper exertion techniques, tension, or severe pelvic floor prolapse masking other pelvic defects (e.g., a significant cystocele obscuring mid-pelvic deficiencies). Recent studies have demonstrated notable differences between intraoperative POP-Q scores obtained under anesthesia and preoperative POP-Q scores. More pronounced prolapse has been observed under anesthesia compared to that observed during the Valsalva maneuver [8]. While these findings suggest that POP-Q evaluations performed under anesthesia may offer greater clinical utility, prior studies did not classify the specific sites of prolapse nor analyze the significance of these differences for surgical decision-making. This study aimed to investigate the discrepancies between POP-Q scores under the Valsalva maneuver before anesthesia and those measured after anesthesia across different anatomical sites of prolapse. Based on these findings, the reference value of such POP-Q differences for guiding surgical planning was preliminarily analyzed.

2. Patients and methods

This is a prospective observational study. Patients undergoing surgery at Chongqing Health Center for Women and Children between January 2023 and June 2023 were selected in this study. The inclusion criteria were as follows: (1) patients diagnosed with Stage III–IV pelvic floor prolapse and scheduled for pelvic floor repair surgery; (2) the availability of complete data. The exclusion criteria were: (1) patients who had undergone uterine or cervical surgical treatment within the past 3 months; (2) pregnant patients; (3) patients with incomplete uterine involution within 1 year postpartum; (4) patients unable to perform the Valsalva maneuver due to severe prolapse symptoms or personal factors; (5) patients in the acute stage of lower urinary tract infection, urinary tract malformation, or inflammatory changes; (6) patients unable to tolerate surgical anesthesia; (7) patients with other serious systemic diseases. This study has been approved by the Ethics Committee of Chongqing Health Center for Women and Children (No. [2023] EC [D] 070), and all patients provided written informed consent.

Patients' basic information (age, height, weight, body mass index, past history, maternity history, and menopause status) and POP-Q scores before and after anesthesia were recorded.

2.1. Determination of cervical traction force during anesthesia

In this study, a senior gynecologist measured parameters in 20 patients in the operating room under consistent conditions. Using a three-dimensional vaginal force-measuring device (to minimize cervical deformation during traction), we pulled the lateral margin of the cervix until cervical displacement ceased and significant resistance was observed, at which point traction was halted. The applied force (N) and the length of cervical extension (cm) were recorded. These values were used to construct a force–displacement curve (analogous to the fiber stress–strain curve). Finally, the mean value of the minimum tractive force (yield point: the force required to fix the C-point of the cervix) across the 20 patients was calculated and adopted as the standard tractive force for use during the operation [9].

2.2. POP-Q score measurements

The quantitative staging system proposed by Bump et al. [7] in the United States was adopted to intuitively show the state and grade of prolapse according to the reference points and diametral lines of the relevant chamber. The examination process was kept sterile, and the measurements were made using a colposcope and a sterile scale (in a measurement range of 1–10 cm).

The POP-Q score was measured in patients before anesthesia. All patients were asked to perform the Valsalva maneuver [10] and parameters of the POP-Q score (Aa, Ba, C, D, gh, pb, Ap, Bp, and tvl) were measured [11]. The plane of the hymen was defined as zero; the points above the hymen were negative; and the points below the hymen were positive. All measurements were in cm (±0.5 cm) and recorded in the grid format, and POP-Q staging was performed before surgery.

The POP-Q score was measured after anesthesia under mechanical stretch. The bladder was emptied with a catheter after general anesthesia in the operating room. During the examination, measurements were made using a colposcope (retraction of the posterior wall of the vagina), Allis forceps (continuous pulling of the lateral margin of the cervix), and a sterile scale (in a measurement range of 1–10 cm). The Allis forceps were used to pull the lateral margin of the cervix with a certain force on a horizontal axis, and all points except gh, tvl, and pb were measured once the prolapsed part was not moving and remained in continuous traction. All measurements were recorded in the grid format, and POP-Q staging was performed again after anesthesia.

The cystocele group involved the anterior vaginal wall (Aa or Ba ≥+2), with or without Stage I–II uterine and posterior vaginal wall prolapse. The uterine prolapse group involved the uterus (C≥+2 or D≥0), with or without Stage I-II cystocele prolapse and rectal prolapse. Cervical elongation was excluded based on POP-Q measurements and direct cervical length measurements with a Foley catheter [12].

2.3. Statistical analysis

SPSS 27.0 software package (IBM, Armonk, NY, USA) was used for statistical analysis. The measurement data conforming to the normal distribution were expressed as means ± standard deviations. One-way analysis of variance was used for comparison among multiple groups. Fisher's least significant difference test was used for pairwise comparison between groups. Kruskal–Wallis test was used for measurement data that did not conform to the normal distribution. Categorical data were compared by the chi-square test and Fisher's exact probability method. A p-value <0.05 was considered statistically significant.

3. Results

A total of 60 patients met the inclusion criteria and had complete data, including 34 patients in the cystocele group and 26 patients in the uterine prolapse group. Patients exhibited POP of Stage III or higher. The proportion of Stage IV prolapse was significantly higher in the uterine prolapse group compared to the cystocele group (27% vs. 5.9%, p=0.025). No statistically significant differences were observed in other clinical characteristics between the two groups (p>0.05), as detailed in Table 1.

Table 1.

Clinical features of the patients.

Clinical feature	Totala (n=60)	Cystocele groupa(n=34)	Uterine prolapsegroupa (n=26)	p-Valueb
POP-Q stage				0.025
Stage III	51 (85)	32 (94)	19 (73)
Stage IV	9 (15)	2 (5.9)	7 (27)
Age, year	64.15±12.90	65.85±10.67	61.92±15.28	0.2
Menopausal status				0.12
No	21 (35)	9 (26)	12 (46)
Yes	39 (65)	25 (74)	14 (54)
BMI, kg/m2	24.32±2.69	24.16±2.82	24.55±2.55	0.6
Number of pregnancies	3.55±1.79	3.62±2.02	3.46±1.48	0.7
Number of vaginal births	2.03±0.96	2.09±0.93	1.96±1.00	0.6
The maximum weight of the fetus	3487.50±368.30	3504.41±369.76	3465.38±372.50	0.7
Related primary diseases				0.8
No	31 (52)	17 (50)	14 (54)
Yes	29 (48)	17 (50)	12 (46)

BMI, body mass index; POP-Q, Pelvic Organ Prolapse Quantitation.

^aValues are presented as n (%) or mean±standard deviation.

^bThe bold value means that the result is statistically significant.

The lateral margin of the cervix was pulled using a three-dimensional vaginal force-measuring device until minimal resistance was encountered during the pulling process (i.e., when traction ceased). The applied force (N) and cervical extension length (cm) were recorded, and a force–displacement curve was plotted (Fig. 1). The mean tractive force across 20 patients was calculated to be 4.81 N.

Figure 1.

Curves of the positional changes of point C under different cervical traction forces. A total of 20 curves represented the 20 POP patients included in the study. The starting point of each curve was the initial value of point C for each patient during the initial assessment. As the traction force gradually increased, the position of point C descended (the y-axis value increased). When the maximum traction force was attained, the position of point C became constant (the turning point of the curve). At this moment, regardless of any changes in the external cervical traction force, the position of point C no longer varied (reaching a straight-line state). POP, pelvic organ prolapse; POP-Q, Pelvic Organ Prolapse Quantitation.

Among the 60 patients, scores for points C, D, and Bp measured under the Valsalva maneuver before anesthesia were significantly lower than those measured under mechanical traction after anesthesia (p<0.05). In the cystocele group, the point Aa scores measured under mechanical traction after anesthesia were significantly lower than those measured under the Valsalva maneuver before anesthesia (p<0.05), as shown in Table 2.

Table 2.

POP-Q scores of patients in different groups before and after anesthesia.

POP-Q point	Cystocele group (n=34)			Uterine prolapse group (n=26)
	Pre-anestheticValsalvaa	Mechanical pullafter anesthesiaa	p-Valueb	Pre-anestheticValsalvaa	Mechanical pullafter anesthesiaa	p-Valueb
Aa	2 (2.0–3.0)	2 (1.0–2.6)	0.016	0 (−2.0–2.0)	1 (0–2.0)	0.2
Ba	3 (2.0–3.1)	2.5 (2.0–3.5)	0.9	1 (−0.3–2.3)	2 (0.9–3.0)	0.2
C	0 (−2.0–1.0)	2 (1.0–3.0)	<0.001	2.5 (2.0–4.0)	3.8 (3.0–4.5)	0.002
D	−2 (−4.0 to −1.0)	−1 (−2.0–0)	0.007	0 (−1.0–1.0)	1 (0–1.5)	0.008
Ap	−3 (−3.0 to −1.8)	−2 (−3.0 to −1.0)	0.057	−2.5 (−3.0 to −2.0)	−2.5 (−3.0 to −1.0)	0.8
Bp	−2 (−3.0 to −1.0)	−1 (−2.1–0.3)	0.012	0 (−3.0–1.0)	−0.5 (−2.0–1.1)	0.005
gh	5 (4.5–5.0)	5 (4.5–5.0)	1	4.7 (3.5–5.0)	5 (4.0–5.0)	0.6
pb	3 (2.0–3.0)	2 (1.4–3.0)	0.8	2.7 (2.0–3.0)	3 (2.0–3.0)	1
tvl	6.8 (6.0–7.0)	6.5 (6.0–7.0)	0.2	7 (6.0–7.0)	6.7 (5.0–7.0)	0.9

POP-Q, Pelvic Organ Prolapse Quantification.

^aValues are presented as median (range).

^bBold values indicate statistically significant results.

After anesthesia, the movement of the point C was significantly greater in the cystocele group compared to the uterine prolapse group (p<0.05). Conversely, the movements of the points Aa, Ba, and Bp were significantly greater in the uterine prolapse group compared to the cystocele group (p<0.05), as presented in Table 3.

Table 3.

Changes of POP-Q point movement before and after anesthesia in patients with major cystocele and major uterine prolapse.

POP-Qpoint	Cystocelegroupa (n=34)	Uterine prolapsegroupa (n=26)	p-Valueb
Aa	−0.59±1.10	0.75±1.42	0.002
Ba	0.18±1.61	0.81±1.33	0.001
C	2.35±2.37	1.06±0.82	<0.001
D	1.24±2.59	1.08±0.69	1
Ap	0.49±1.76	0.12±1.88	0.4
Bp	0.93±1.26	1.52±1.63	<0.001
gh	−0.24±1.10	−0.19±1.52	1
pb	0.18±1.61	0.15±1.42	1
tvl	−0.07±1.60	−0.12±1.23	1

POP-Q, Pelvic Organ Prolapse Quantitation.

^aValues are presented as mean±standard deviation.

^bBold values indicate statistically significant results.

4. Discussion

The incidence rate of POP was 40% in the age group of 50–79 years, with 13% requiring surgical intervention [13,14]. In China, the reported incidence rate of pelvic floor dysfunction is as high as 28%, and it can reach 40% for individuals aged 45 years or older [15]. The POP-Q score plays an important role in guiding the selection of the surgical approach [16,17]. However, its accuracy remains a subject of debate. Vierhout et al. [18], Chao et al. [19], and Vineyard et al. [20] have noted discrepancies between preoperative and intraoperative POP-Q scores. These studies did not conduct separate statistical analyses based on different prolapse sites due to variations in defect locations and pathogenesis between first-level and second-level defects, which could affect the accuracy of judgment when mixed statistics are used. In our study, patients with uterine prolapse and cystocele were differentiated, and the differences in POP-Q scores before and after anesthesia were compared separately. Additionally, the causes of these differences were analyzed to evaluate their reference value in selecting appropriate surgical approaches.

An earlier study indicated that the tractive force of the cervix ranged from 4.91 N to 19.65 N, which is approximately equivalent to the weight force exerted by a mass of 0.5 kg–2.0 kg under Earth's gravity, reflecting the forces associated with natural uterine relaxation [21]. Vierhout et al. [18] selected 0.5 N as a constant tractive force to minimize excessive cervical traction. Smith et al. [9] chose 17.8 N as the constant tractive force during cervical tensile testing. Variations in tractive force across studies may be attributed to the following factors. First, differences in measurement methods and equipment can lead to inconsistent results. Second, the pelvic floor structure exhibits resistance to a certain degree of tractive force; however, the extent of force that populations in different regions can tolerate may vary. Third, excessive traction may cause injuries to pelvic muscles, ligaments, and other structures [22,23]. To standardize the intraoperative cervical tractive force, we recorded the C-point displacement of 20 patients under varying tractive forces, plotted the cervical force–displacement curve, and calculated that the minimum tractive force required for cervical traction after anesthesia was 4.81 N.

We found that in both the uterine prolapse and cystocele groups, the POP-Q scores for points C, D, and Bp under mechanical traction after anesthesia were higher than those obtained during the Valsalva maneuver before anesthesia. This finding is consistent with the results reported by Chaudhuri [8]. Doumouchtsis et al. [24] demonstrated that the values of points Aa, Ap, Ba, Bp, C, and D measured under mechanical stretch were all higher than those obtained during the Valsalva maneuver. However, we observed that compared to the Valsalva maneuver before anesthesia, the scores for points Aa, Ap, and Ba under traction after anesthesia did not significantly increase and even decreased in some cases. We believe this discrepancy may arise from the lack of classification of prolapse sites, as uterine prolapse represents a horizontal defect, while cystocele involves a two-level defect. These two types of prolapse differ fundamentally in nature, and combining them in statistical analysis inevitably introduces errors.

In the uterine prolapse group, the values of points C, D, and Bp under mechanical stretch after anesthesia were significantly higher than those during the Valsalva maneuver before anesthesia, whereas the scores for points Aa, Ba, and Ap remained unchanged. This increase in C, D, and Bp scores may be attributed to the relaxation of pelvic floor muscles induced by anesthesia. The stability of Aa, Ba, and Ap scores could indicate that the pre-anesthesia cystocele might result from bladder displacement secondary to uterine prolapse rather than true cystocele. Therefore, relying solely on the Valsalva maneuver scores before anesthesia for surgical planning in patients with uterine prolapse may not provide a comprehensive evaluation.

In the cystocele group, the values of points C, D, and Bp under mechanical traction after anesthesia increased significantly compared to those during the Valsalva maneuver before anesthesia, while the scores for points Ba and Ap showed no significant change. Analysis revealed that the degree of movement of points C, D, and Bp after anesthesia was greater in the cystocele group than in the uterine prolapse group, suggesting that patients with cystocele may also exhibit varying degrees of uterine prolapse. However, the vaginal wall prolapse during the Valsalva maneuver often masks the severity of uterine prolapse, which may not be fully evaluated by the POP-Q system during the Valsalva maneuver before anesthesia. Consequently, moderate-to-severe cystocele patients combined with mild-to-moderate uterine prolapse frequently undergo anterior vaginal wall repair or anterior pelvic floor reconstruction without addressing the uterine prolapse, leading to an increased postoperative recurrence rate. This aligns with Petros's “global theory” and Delancey's “horizontal support theory” and “compartment theory”, which propose that POP does not occur independently, and three-chamber prolapse typically coexists. The middle pelvic cavity serves as the core point of vertex support, and any abnormality in vertex support increases the incidence of anterior and posterior pelvic cavity prolapse [25,26]. Therefore, for patients with cystocele, the evaluation of points C and D should be based on measurements taken under anesthesia, and intraoperative correction of middle pelvic defects is necessary to prevent postoperative uterine prolapse recurrence.

Additionally, Chen et al. [27] suggested that the assessment of point Aa during the Valsalva maneuver is accurate. When the contractile force of the levator ani muscle decreases to a certain level and the genital hiatus opens, the vaginal wall bears the pressure difference caused by relatively high intra-abdominal pressure and relatively low atmospheric pressure, resulting in anterior vaginal wall displacement and prolapse. This pressure difference is adequately achieved during the Valsalva maneuver but becomes uneven during mechanical traction after anesthesia due to variations in the elasticity and length of the vaginal wall tissue, leading to inaccurate evaluation of the vaginal wall under mechanical traction. Point Ba is more influenced by uterine descent, and the increase in point C after anesthesia offsets the impact of lower abdominal pressure, explaining the lack of statistical difference in Ba point changes before and after anesthesia.

There are still some limitations in this study. First, the changes in POP-Q scores before and after anesthesia were monitored without additional imaging support. Dynamic monitoring of the movement degree of each prolapsed organ in different patient states could provide a more accurate assessment of individual patient conditions. Second, the sample size of this study was relatively small. Future studies should further analyze the differences between simple prolapse and mixed prolapse, expand the sample size, and investigate the characteristics of patients with posterior pelvic prolapse to enhance the generalizability of the findings.

5. Conclusion

The increased scores of points C, D, and Bp after anesthesia in both groups suggest that the evaluation of uterine prolapse should be based on results obtained after anesthesia. Conversely, the evaluation of cystocele should rely on results obtained before anesthesia due to the decrease in point Aa scores after anesthesia.

Author contributions

Study concept and design: Pan Hu, Hui Nie, Limei Zhao, Chunhua Han, Lubin Liu.

Data acquisition: Su Lin, Li Lei, Yingxia He, Lin Feng.

Data analysis: Su Lin, Pan Hu, Hui Nie, Li Lei.

Drafting of the manuscript: Su Lin, Pan Hu, Hui Nie.

Critical revision of the manuscript: Limei Zhao, Chunhua Han, Lubin Liu.

Conflicts of interest

The authors declare no conflict of interest.