Wide Genital Hiatus (GH) and Short Perineal Body (PB) as Risk Factors for Stage III-IV Uterine Prolapse

Background: Pelvic organ prolapse (POP) is a medical condition characterized by the descent of the uterus and other pelvic organs into the vaginal lumen due to weakened pelvic floor structures, resulting in clinical manifestations such as protrusion through the vaginal canal. The incidence of POP is increasing significantly, particularly among older women. The perineal body and genital hiatus are believed to play roles in the occurrence of POP. The perineal body is a crucial component of the pelvic floor as it supports the vagina and uterus, while a wide genital hiatus is implicated in the progression and association with uterine prolapse. Understanding the dimensions of the perineal body and genital hiatus may provide new insights into the risk factors for POP. This study aims to demonstrate that a wide genital hiatus and short perineal body are risk factors for POP, particularly in cases of stage III-IV uterine prolapse.

Methods: This case-control analytic study assessed the relationship between a wide genital hiatus and a short perineal body with the occurrence of POP. The case group included patients with stage III-IV uterine prolapse, while the control group comprised individuals without prolapse.

Results: A narrow genital hiatus (<5 cm) and a short perineal body (<3 cm) were found to be significant risk factors for POP. A narrow genital hiatus increased the risk of stage III–IV uterine prolapse by fourfold (OR 4.91; 95% CI 3.92–57.28; p <0.004). Similarly, a short perineal body was also identified as a significant risk factor, increasing the risk of uterine prolapse fourfold (OR 4.66; 95% CI 3.75–56.22; p <0.018).

Conclusion: A narrow genital hiatus (<5 cm) and a short perineal body (<3 cm) are significant risk factors for pelvic organ prolapse, increasing the risk by fourfold.

Introduction

Pelvic Organ Prolapse (POP) is a medical condition characterized by the descent of the uterus and other pelvic organs into the vaginal lumen due to weakened pelvic floor structures, resulting in clinical manifestations such as protrusion through or beyond the vaginal canal. The incidence of POP has significantly increased, particularly among older women, necessitating management strategies that address contributory risk factors to reduce morbidity associated with the condition [1], [2]. Barber and Maher estimated that approximately 50% of women will experience POP during their lifetime, with the proportion of at-risk women expected to increase, projecting that 25% of women will be over 65 years old by 2030 [3], [4]. By 2050, symptomatic cases of POP are estimated to increase by 46% to 200%, affecting approximately 4.9 million to 9.2 million women [3]. Despite these alarming statistics, only 12% of women diagnosed with POP during physical examinations report related symptoms [5].

The perineal body (PB) is a crucial component of the pelvic floor, positioned directly below the vagina and uterus [6]. Studies have shown that a wide genital hiatus (GH) may play a role in the progression of POP and is associated with uterine prolapse. Delancey reported that women with prolapse have larger GH dimensions compared to controls and that GH size may influence the recurrence of prolapse following surgical repair [7]. Weakness in the levator ani muscle, caused by trauma or injury, along with an enlarged GH, contributes to the progression of POP [8]. In Indonesia, a study reported 30 cases of uterine prolapse treated in the Obstetrics and Gynecology ward of RSUP Dr. Sardjito Hospital in 2013, while 82 cases of POP were reported in 2009 at RSUP Prof. Ngoerah Hospital, increasing to 91 cases in 2015, with 36 requiring surgical intervention [9]. Risk factors such as parity over three and menopausal status have been identified as significant contributors to POP [10]. However, hormonal therapy and BMI have shown inconsistent correlations with the incidence of POP [11], [12].

Understanding the roles of the genital hiatus and perineal body in POP risk provides valuable insights into this condition. This study aims to demonstrate that a wide genital hiatus and short perineal body are significant risk factors for the occurrence of stage III-IV uterine prolapse.

Materials and Methods

Study Design and Population

This study employed an analytical case-control design to assess the relationship between genital hiatus (GH) width and perineal body (PB) length with pelvic organ prolapse (POP). The case group consisted of women diagnosed with stage III-IV uterine prolapse based on the Pelvic Organ Prolapse Quantification (POP-Q) system, while the control group included women without prolapse. The study was conducted at RSUP Prof. Dr. I.G.N.G. Ngoerah General Hospital, Denpasar, Indonesia, from January to December 2024.

Inclusion and Exclusion Criteria

The inclusion criteria for cases included women diagnosed with stage III-IV uterine prolapse using the POP-Q system. Controls were women without any prolapse identified during clinical examination. Exclusion criteria included women with prior pelvic surgery, congenital pelvic anomalies, or incomplete medical records.

Sample Size

The sample size was calculated using the formula for case-control studies, with an expected odds ratio of 4, a confidence interval of 95%, and a power of 80%. The required sample size for each group was 45, resulting in a total of 90 participants.

Data Collection

Clinical data were collected from medical records and direct pelvic examinations performed by trained clinicians using the POP-Q system. Measurements of genital hiatus width and perineal body length were taken in centimeters. A genital hiatus width ≥5 cm and a perineal body length ≥3 cm were categorized as normal, while measurements below these thresholds were considered narrow and short, respectively.

Statistical Analysis

Data analysis was performed using SPSS v25. Univariate analysis was used to describe the distribution of variables. The chi-square test and logistic regression analysis were conducted to evaluate the association between genital hiatus width, perineal body length, and the presence of stage III-IV uterine prolapse. Results were presented as odds ratios (ORs) with 95% confidence intervals (CIs), and a p-value <0.05 was considered statistically significant.

Results

Distribution of Age, Parity, BMI, and Occupation in Case and Control Groups

The distribution of age, parity, BMI, and occupation among patients with stage III-IV uterine prolapse treated at RSUP Prof. Dr. I.G.N.G. Ngoerah General Hospital, Denpasar, from January 2023 to December 2023, is presented in Table I. The majority of cases were observed in patients aged ≥65 years, comprising 16 cases (36.3%), followed by patients aged 60–64 years with 10 cases (22.8%). Other age groups included 55–59 years and 50–54 years, each with 6 cases (13.6%), while the 45–49 years group accounted for 4 cases (9.1%). The smallest number of cases was found in patients aged 40–44 years and <40 years, each contributing 1 case (2.3%).

Table I. Distribution of Medical Records Data of Uterine Prolapse Patients

Patient characteristics	Frequency (n)	Proportion (%)
Age
35–39 years	1	2.3
40–44 years	1	2.3
45–49 years	4	9.1
50–54 years	6	13.6
55–59 years	6	13.6
60–64 years	10	22.8
>65 years	16	36.3
Parity
Nulliparous	2	4.5
Primiparous	2	4.5
Multiparous	40	91.0
BMI
Underweight (<18.5 kg/m²)	3	6.8
Normal (18.5–24.9 kg/m²)	21	47.7
Overweight (>25 kg/m²)	20	45.5
Occupation
Light	36	81.9
Heavy	8	18.1
Total	44	100

Regarding parity, multiparous women constituted the majority, with 40 cases (91.0%), whereas nulliparous and primiparous women accounted for only 2 cases each (4.5%). In terms of BMI, the highest number of cases was observed in patients with a normal BMI (18.5–24.9 kg/m²), totaling 21 cases (47.7%), followed by overweight patients (>25 kg/m²) with 20 cases (45.5%). Patients categorized as underweight (<18.5 kg/m²) represented the smallest group, with only 3 cases (6.8%).

When examining occupation, most cases were observed in patients performing light work, accounting for 36 cases (81.9%), while those involved in heavy work contributed 8 cases (18.1%). These findings highlight the demographic and occupational characteristics associated with patients experiencing stage III–IV uterine prolapse in this study.

Distribution of Age, BMI, Parity, and Occupation in Case and Control Groups

In this case-control study, statistical tests were conducted to evaluate the relationships between age, BMI, parity, and occupation in the case and control groups. Independent t-tests were applied to the age and BMI variables, while the Mann-Whitney U test was used for parity, and Fisher’s exact test was employed for occupation. The mean age of women in the case group was 61.81 ± 10.8 years, compared to 56.23 ± 6.3 years in the control group, with a p-value of 0.350 (p > 0.05). This indicates no significant difference in age between the case and control groups. Similarly, the mean BMI of women in the case group was 24.30 ± 3.3 kg/m², while in the control group it was 25.57 ± 2.9 kg/m², with a p-value of 0.646 (p > 0.05), showing no significant difference in BMI between the groups.

The median parity for both the case and control groups was 2, with an interquartile range of 2 in both groups. The p-value was 0.515 (p > 0.05), indicating no significant difference in parity between the case and control groups. Regarding occupation, 17 women (77.3%) in the case group and 19 women (86.4%) in the control group were involved in heavy work. Fisher’s exact test yielded a p-value of 0.404 (p > 0.05), indicating no significant difference in the prevalence of heavy work between the two groups.

As shown in Table II, the p-values for age, BMI, parity, and occupation are all greater than 0.05, indicating no significant differences in these variables between the case and control groups. These findings suggest that these factors did not significantly differentiate women with stage III-IV uterine prolapse from those without prolapse in this study.

Table II. Characteristics of Subjects Based on Case and Control Groups

Variable	Group	Control (n = 22)	p-value
Age (years), mean ± SD	61.81 ± 10.8	56.23 ± 6.3	0.350a
BMI (kg/m²), mean ± SD	24.30 ± 3.3	25.57 ± 2.9	0.646a
Parity (children), median ± SD	2.00 ± 0.0	2.00 ± 0.0	0.515b
Occupation, n (%)
Light	17 (77.3%)	19 (86.4%)	0.404c
Heavy	5 (22.7%)	3 (13.6%)

Relationship Between Genital Hiatus Width and Pelvic Organ Prolapse Incidence in Patients with Stage III-IV Uterine Prolapse

The width of the genital hiatus was categorized into two groups: wide (genital hiatus width ≥5 cm) and narrow (genital hiatus width <5 cm). To evaluate the relationship between genital hiatus width and the incidence of pelvic organ prolapse (POP) in patients with stage III–IV uterine prolapse, a Chi-Square test was conducted. The results are presented in Table III.

Table III. Risk of Genital Hiatus Width with Incidence of Pelvic Organ Prolapse in Stage III-IV Uterine Prolapse Patients

Genital Hiatus	Case (n)	Control (n)	OR	95% CI
Wide (≥5 cm)	17	9	4.91	3.92–57.28
Narrow (<5 cm)	5	13

The analysis showed that a wide genital hiatus is a significant risk factor for the occurrence of POP in patients with stage III-IV uterine prolapse (p = 0.002) compared to a narrow genital hiatus. This finding underscores the importance of genital hiatus width as a key anatomical factor contributing to the progression of advanced uterine prolapse.

Relationship Between Perineal Body Length and Pelvic Organ Prolapse Incidence in Patients with Stage III-IV Uterine Prolapse

The length of the perineal body was categorized into two groups: short (≤3 cm) and long (≥4 cm). To assess the relationship between perineal body length and the incidence of pelvic organ prolapse (POP) in patients with stage III–IV uterine prolapse, a Chi-Square test was performed. The results are detailed in Table IV.

Table IV. Risk of Perineal Body Length with Incidence of Pelvic Organ Prolapse in Stage III-IV Uterine Prolapse Patients

Perineal body	Case (n)	Control (n)	OR	95% CI
Short (≤3 cm)	16	8	4.66	3.73–56.22
Long (≥4 cm)	6	14

The analysis revealed that a short perineal body is a significant risk factor for the occurrence of POP in patients with stage III-IV uterine prolapse (p = 0.018) compared to a long perineal body. This finding highlights the role of perineal body length as a critical anatomical factor in the progression of advanced uterine prolapse.

Discussion

Pelvic organ prolapse (POP), including uterine prolapse, is a condition caused by the weakening of pelvic floor structures, leading to the descent of the uterus and other organs into or through the vaginal canal. This study analyzed the relationships between age, parity, BMI, occupation, genital hiatus width, and perineal body length with the incidence of stage III–IV uterine prolapse, finding significant associations with anatomical factors such as genital hiatus width and perineal body length. The results showed no statistically significant differences between the case and control groups regarding age, parity, BMI, or occupation. Similar findings were reported by Vergeldt et al. [13], who highlighted that while BMI and parity are significant risk factors for POP when considered categorically, their significance diminishes when analyzed as continuous variables. Shalom et al. [14] also observed no significant differences in BMI between groups with varying stages of prolapse. However, advanced age, multiparity, and BMI remain widely acknowledged as contributing factors to POP development [15].

In this study, a wide genital hiatus was identified as a significant risk factor for stage III-IV uterine prolapse, with an odds ratio (OR) of 4.91 (95% CI: 3.92–57.28, p = 0.004). This finding aligns with previous studies, including Trowbridge et al. [16], who found that women over 60 years old with advanced uterine prolapse often exhibit a genital hiatus width >5 cm (p < 0.05). Similarly, a study by Dökmeci et al. [17] reported a significant association between a wide genital hiatus and POP in Turkish women, supporting the role of levator ani muscle dysfunction and ligamentous stretching in prolapse progression.

A short perineal body was also identified as a significant risk factor for advanced uterine prolapse, with an OR of 4.66 (95% CI: 3.73–56.22, p = 0.018). The perineal body is considered the “center of gravity” for the perineum, providing support to surrounding pelvic structures. Nisa et al. [18] demonstrated that women with a perineal body length ≤3 cm were at significantly higher risk for stage III-IV uterine prolapse (p = 0.001). This finding is consistent with Purwara et al. [19], who reported that older women with shorter perineal bodies were more likely to develop advanced prolapse, highlighting age-related changes in collagen composition and tissue elasticity.

The results also confirm that damage to the levator ani muscle leads to genital hiatus widening and subsequent prolapse. Moalli et al. [20] noted that the genital hiatus and perineal body are critical anatomical landmarks evaluated using the Pelvic Organ Prolapse Quantification (POP-Q) system, with their dimensions being predictive of prolapse severity. Additionally, Kim et al. [21] reported that a short perineal body increased the risk of POP by 6.3 times (p < 0.001), supporting the hypothesis that pelvic floor support diminishes with age-related changes in connective tissue properties. These findings emphasize the importance of anatomical factors in POP development. A wide genital hiatus and a short perineal body compromise the structural integrity of the pelvic floor, predisposing women to advanced uterine prolapse. Future research should explore preventive measures and interventions targeting these risk factors to reduce the burden of POP.

Conclusion

This study concludes that a wide genital hiatus and a short perineal body are significant risk factors for the development of stage III-IV uterine prolapse. These anatomical factors compromise pelvic floor support, contributing to the progression of advanced uterine prolapse.

Based on these findings, further research is recommended to explore the predictive value of a wide genital hiatus and a short perineal body in the occurrence of stage III–IV uterine prolapse. Additionally, larger-scale studies involving a more extensive sample size are necessary to validate the results and establish these factors as reliable indicators for identifying women at risk of advanced uterine prolapse.