Examination of the relationship between post-voiding residual urine volume and patient-reported urinary symptoms in postmenopausal women

Abstract

Introduction and Hypothesis

Post-void residual (PVR) urine volume is routinely evaluated in women with urinary incontinence and/or pelvic organ prolapse (POP). However, its clinical relevance in postmenopausal women without these conditions remains insufficiently defined. This exploratory study aimed to investigate the association between PVR volume and patient-reported urinary symptom burden, as measured by the King’s Health Questionnaire (KHQ), in postmenopausal women without urinary incontinence or prolapse. A secondary objective was to descriptively compare PVR volumes and uroflowmetry parameters between women reporting no urinary impact and those reporting mild-to-moderate impact.

Methods

Seventy postmenopausal women evaluated at the Gynecology and Urogynecology Clinics of Karadeniz Technical University Faculty of Medicine between 2022 and 2024 were enrolled in this cross-sectional observational study. Demographic data, uroflowmetry parameters, PVR volumes measured by transabdominal ultrasonography, and KHQ scores were recorded. Participants were stratified according to their response to a global KHQ impact item reflecting perceived urinary burden. Statistical analyses were conducted using SPSS, with significance set at p < 0.05. No a priori sample size or power calculation was performed, and the study should therefore be interpreted as exploratory. Correlation coefficients and 95% confidence intervals were calculated.

Results

The mean age of participants was 55.5 ± 4.1 years. As expected based on the stratification criterion, women reporting urinary impact demonstrated higher KHQ domain scores. However, no statistically significant differences were observed between groups in uroflowmetry parameters or PVR volumes. Furthermore, no significant correlations were identified between PVR volume and KHQ scores in the overall cohort (p > 0.05). All correlations were weak and confidence intervals crossed zero.

Conclusions

In this exploratory cross-sectional cohort of postmenopausal women without incontinence or prolapse, no statistically significant association was detected between PVR volume and patient-reported urinary impact. Given the limited sample size, exploratory symptom stratification, and use of a predominantly incontinence-oriented questionnaire, these findings should be interpreted as inconclusive rather than confirmatory of absence of association. In addition, the use of the King’s Health Questionnaire, which is primarily designed for urinary incontinence, may have limited the ability to capture voiding-specific symptoms. Larger, methodologically standardized studies are warranted to clarify the role of PVR in this population.

Brief summary

This study found no association between post-void residual urine volume and voiding symptoms or quality of life in postmenopausal women without incontinence or prolapse.

Introduction

Menopause is defined as the absence of menstruation for 12 consecutive months [1–3]. The postmenopausal phase is characterized by hormonal changes due to cessation of ovarian function [4].

These physiological changes may vary significantly among women. While some experience minimal symptoms, others may go through more severe and disruptive effects. Hormonal changes during this period particularly affect the urogenital system [5, 6].

The primary cause of urogenital symptoms is a decrease in estrogen levels [7]. This hormonal decline can lead to vaginal dryness, atrophy, urinary symptoms, and sexual dysfunction. Common urinary symptoms include recurrent urinary tract infections, frequent urination, urgency, urinary incontinence, and incomplete bladder emptying [7].

Regardless of age, the initial tests for evaluating urinary symptoms in women typically include urinalysis and urine culture [8]. These tests help detect or rule out urinary tract infections. Another key first-line evaluation is the measurement of post-void residual (PVR) urine volume — the amount of urine remaining in the bladder after voiding [8, 9].

In postmenopausal women, PVR measurement provides information regarding bladder emptying efficiency and potential risk of infection [8, 9].

Although PVR measurement is widely used in the evaluation of women with urinary incontinence or pelvic organ prolapse, its potential role in the broader spectrum of lower urinary tract symptoms has not been clearly established. Elevated PVR has been associated with an increased risk of urinary tract infections, incomplete bladder emptying, and reduced quality of life, highlighting its possible clinical relevance beyond incontinence and prolapse. However, most previous studies have primarily focused on populations with overt pelvic floor disorders, leaving uncertainty about whether PVR contributes to or correlates with urinary symptoms in postmenopausal women without these conditions. Addressing this knowledge gap is important, as identifying a relationship between PVR and urinary symptoms in this population may facilitate earlier recognition of bladder dysfunction, improve symptom management, and support the development of more tailored therapeutic strategies. However, it should be noted that the clinical relevance of PVR is most clearly established in populations with bladder outlet obstruction, neurogenic dysfunction, or advanced pelvic floor disorders, and its role in otherwise healthy postmenopausal women remains uncertain.

Although PVR measurement is commonly used in women with urinary incontinence and pelvic organ prolapse, its clinical significance in postmenopausal women without overt pelvic floor dysfunction remains unclear. Moreover, data evaluating the relationship between residual urine volume and patient-reported urinary symptoms in non-incontinent postmenopausal populations are limited. Therefore, this exploratory study aimed to investigate the association between PVR volume and urinary symptom burden in postmenopausal women without urinary incontinence or pelvic organ prolapse.

Material & method

A total of 70 patients who presented to the Gynecology and Urogynecology outpatient clinics of the Department of Obstetrics and Gynecology at Karadeniz Technical University between 2022 and 2024 and met the study inclusion criteria were enrolled. The study was designed as a cross - sectional study.

Inclusion criteria for the study

The study was conducted among postmenopausal women who were evaluated at the Gynecology and Urogynecology outpatient clinic of the Department of Obstetrics and Gynecology at Karadeniz Technical University (KTÜ). Importantly, these patients did not present to the clinic with complaints related to lower urinary tract symptoms. All participants were initially asked to void, and urinary tract infection was ruled out using a dipstick urinalysis. Only those who were asymptomatic during urination and tested negative for both nitrite and leukocyte esterase were included.

Eligible participants met all of the following criteria:

• Postmenopausal status, defined as women aged 50–70 years with at least 12 consecutive months of amenorrhea (to ensure age-related standardization)

• Voluntary participation and provision of informed consent

• No evidence of urinary tract infection (confirmed by negative dipstick test for nitrite and leukocyte esterase)

• Absence of systemic diseases known to affect urinary tract function (e.g., diabetes mellitus, hypertension)

• Not using medications that could alter urinary system function (e.g., diuretic antihypertensives, antidiabetics)

• No history or clinical findings of urinary incontinence and/or palpable pelvic organ prolapse

Exclusion criteria for participation in the study

Participants were excluded from the study if they met any of the following criteria:

• Declined or did not provide informed consent to participate

• Presence of a urinary tract infection (confirmed by positive dipstick for nitrite and/or leukocyte esterase)

• Diagnosis of a systemic disease that may affect urinary tract function (e.g., diabetes mellitus, hypertension)

• Use of medications known to influence urinary function (e.g., diuretic antihypertensives, antidiabetic agents)

• Presence of urinary incontinence and/or a history of palpable pelvic organ prolapse

• Detection of second-degree or higher pelvic organ prolapse during pelvic examination

• Women who had previously had surgery for either POP or incontinence

Recorded demographic data

For each participant included in the study, an individual follow-up form was created to systematically record demographic and clinical information. The following variables were documented:

• Age

• Body Mass Index (BMI)

• Obstetric history, including gravida, parity, abortion, and curettage

• Medical and surgical history

• Current medication use

Uroflowmeter data recorded in the study

The uroflowmetry procedure was performed on participants who were confirmed to be free of urinary tract infection and met the study inclusion criteria. All measurements were conducted under outpatient clinic conditions, ensuring patient privacy and that each participant was alone during the procedure. The following uroflowmetric parameters were recorded:

• Mean urine flow rate (mL/s)

• Maximum urine flow rate (mL/s)

• Voided urine volume (mL)

• Time to maximum flow (s)

Ultrasound data recorded in the study

Following the voiding test, post-void residual (PVR) urine volume was measured using transabdominal ultrasonography (TAUS) performed immediately after micturition. All ultrasound examinations were conducted by the same clinician (K.U.) to ensure consistency. A 3.5 MHz convex probe was used for the assessment. Measurements were obtained from sagittal and transverse sections of the bladder, using images acquired by placing the probe a few centimeters above the pubic symphysis. Bladder volume was calculated using the technique described by Szabo et al. in 1981 [10].

Questionnaire form used and recorded in the study

To evaluate urinary symptoms and their impact on quality of life, the King’s Health Questionnaire (KHQ) was administered to all participants by the same researcher (K.U.).

King’s health questionnaire

The KHQ, developed by Kelleher et al. in 1997 [11], is a validated instrument for assessing the quality of life in individuals with urinary symptoms. The Turkish validity and reliability study of the questionnaire was conducted by Kaya et al. [12]. It consists of 21 questions grouped into nine categories:

• General health perception

• Impact of incontinence

• Role limitations

• Physical limitations

• Social limitations

• Personal relationships

• Emotions

• Sleep/energy

• Severity measures

Each category is scored independently. For the purposes of this study, data were analyzed both collectively and comparatively based on participants’ responses to Question 2 of the KHQ. This question was used to distinguish participants based on the presence of urinary symptoms other than incontinence.

This grouping strategy was exploratory and intended to reflect perceived urinary impact rather than to serve as a validated diagnostic classification of voiding dysfunction. Because classification was derived from a global KHQ item, subsequent between-group comparisons of KHQ domain scores should be interpreted as descriptive rather than independent inferential analyses. It should be emphasized that the KHQ is primarily designed to assess quality of life in women with urinary incontinence and may not adequately capture voiding-phase symptoms such as hesitancy, intermittency, straining, or sensation of incomplete emptying.

Accordingly, participants were divided into two groups:

• Group Asymptomatic: 40 patients who reported no urinary symptoms

• Group Symptomatic: 30 patients who reported mild to moderate urinary symptoms

It should be noted that symptom-based grouping relied on a single item of the King’s Health Questionnaire, which may not fully capture the complexity or spectrum of lower urinary tract symptoms. Comparative analyses were performed between these two groups to assess the relationship between post-void residual urine volume and the presence of voiding symptoms. These groupings were exploratory and should not be interpreted as clinically validated categories of voiding dysfunction.

Statistical analysis

All statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS), version 21.0. The collected data, including demographic characteristics, uroflowmetry results, ultrasonography measurements, and questionnaire scores, were systematically evaluated.

The Shapiro-Wilk test was used to assess the normality of data distribution. To investigate the relationship between post-void residual urine volume and symptom scores obtained from the King’s Health Questionnaire, the Spearman correlation test was applied due to the non-parametric nature of the data.

A p-value < 0.05 was considered indicative of statistical significance in all analyses. No a priori sample size or power calculation was performed. Therefore, the study may be underpowered to detect small-to-moderate associations, and the results should be interpreted with caution. Confidence intervals (95%) for correlation coefficients were calculated using Fisher’s z transformation.

Results

A total of 70 postmenopausal women who met the study inclusion criteria were included in the analysis. Patients were stratified into two groups based on their response to the KHQ item “How much do you think your urinary problem affects your life?“, listed under the “Incontinence Impact” domain.

Group Asymptomatic consisted of 40 patients who reported no impact.

Group Symptomatic included 30 patients who reported a slight or moderate impact.

Although none of the patients reported urinary incontinence, other urinary symptoms were considered in this stratification.

The mean age of the participants was 55.5 ± 4.1 years, with an age range of 50 to 67 years. The mean Body Mass Index (BMI) was 27.0, and the mean gravida and parity values were 3 and 2, respectively. None of the patients had a notable medical or surgical history, and none were using medications. The demographic characteristics of the study population are presented in (Table 1). Comparative analysis between the two groups revealed no statistically significant differences in demographic variables (p > 0.05), as shown in (Table 1).

Table 1.

Demographic data and comparative analysis of groups

	All patients n = 70	Group Asymptomatic n = 40	Group Symptomatic n = 30	p
Age	55,5 ± 4,1 (50–67)	55,5 ± 4,2 (50–67)	55,6 ± 4,2 (50–66)	0,921
Weight	74,5 ± 8,5 (57–96)	74 ± 8,6 (57–93)	74,8 ± 7,6 (62–96)	0,580
Height	164,5 ± 7,4 (152–182)	164,8 ± 7,5 (152–179)	164,1 ± 7,4 (152–182)	0,682
Body Mass Index	27 (20–36)	27 (20–36)	27 (20–34)	0,409
Gravida	3 (0–8)	3 (0–7)	3 (0–8)	1
Parity	2 (0–6)	3 (0–5)	2 (0–6)	0,286
Abortion	0 (0–4)	0 (0–1)	1 (0–4)	0,072
Curettage	0 (0–4)	0 (0–4)	1 (0–4)	0,831

The mean total King’s Health Questionnaire (KHQ) score was 73.4 ± 64.7. Detailed scores for each domain of the questionnaire are provided in (Table 2). As anticipated given the grouping criterion, participants classified as symptomatic demonstrated higher scores across most KHQ domains (p < 0.05). These comparisons were performed to descriptively characterize perceived symptom burden between groups rather than to validate the grouping structure.

Table 2.

Comparison of King’s health questionnaire results and uroflowmetry data across groups

		All patients n = 70	Group Asymptomatic n = 40	Group Symptomatic n = 30	p
King’s Health Questionnaire	General Health Perception	28,9 ± 16,3 (0–75)	25 ± 16 (0–75)	34,2 ± 15,4 (0–50)	0,018
	Incontinence Impact	18,1 ± 23,2 (0–66,6)	0	42,2 ± 14,9 (33,3–66,6)	< 0,001
	Role Limitations	4 ± 9,6 (0–33,3)	0,4 ± 2,6 (0–16,6)	8,9 ± 12,9 (0–33,3)	< 0,001
	Physical Limitations	9 ± 15,9 (0–83,3)	1,2 ± 4,4 (0–16,6)	19,4 ± 19,6 (0–83,30)	< 0,001
	Social Limitations	1,7 ± 6,2 (0–33,3)	0	3,9 ± 9,1 (0–33,3)	0,009
	Personal Relationships	0,2 ± 1,3 (0–11,1)	0	0,4 ± 2 (0–11,1)	0,251
	Emotions	3,2 ± 9,1 (0–33,3)	1,1 ± 5,5 (0–33,3)	6,1 ± 12,1 (0–33,3)	0,024
	Sleep/Energy	8,1 ± 10 (0–33,3)	3,7 ± 7 (0–16,6)	14 ± 10,5 (0–33,3)	< 0,001
	Severity Measures	0,9 ± 4,1 (0–26,6)	0	2,2 ± 6,1 (0–26,6)	0,025
	Total Score	73,4 ± 64,7 (0- 291,4)	31,5 ± 22,5 (0–85,9)	129,3 ± 60,3 (33,3- 219,4)	< 0,001
Volume voided		368,6 ± 231,1 (26,5- 1206)	351,7 ± 243,6 (26,5- 1206)	391,1 ± 215,2 (47,4- 787)	0,477
Maximum Urine Flow Rate		35,6 ± 20,1 (4,3–91)	33,4 ± 20,6 (4,3–91)	38,6 ± 19,4 (6,5–90,3)	0,285
Average Urine Flow Rate		12,9 ± 6,1 (2,3–29,1)	12,1 ± 5,9 (2,3–24,7)	13,9 ± 6,2 (3,9–29,1)	0,228
Urination Time		28,7 ± 16,7 (5,4–94,4)	28,6 ± 16,7 (5,4–89,3)	28,9 ± 16,9 (7–94,4)	0,939
Post-Void Residual Urine Volume		38,7 ± 37,6 (1- 171)	40 ± 42,2 (1- 171)	37,1 ± 31,2 (1- 154)	0,738

These findings are detailed in (Table 2).

The mean voided urine volume, as measured by uroflowmetry, was 368.6 ± 231.1 mL, and the mean post-void residual (PVR) urine volume, assessed by transabdominal ultrasonography, was 38.7 ± 37.6 mL. These results are summarized in (Table 2). When comparing uroflowmetry parameters and post-void residual urine volumes between Group Asymptomatic and Group Symptomatic, no statistically significant differences were observed (p > 0.05). The data are presented in (Table 2). It should be noted that PVR values in this cohort were predominantly within clinically accepted normal limits, resulting in limited variability.

In the overall patient population, no statistically significant correlations were found between post-void residual urine volume and KHQ domain scores (p > 0.05). These results are shown in (Table 3). Similarly, no significant correlations were observed between post-void residual urine volume and KHQ scores in either Group Asymptomatic or Group Symptomatic when analyzed separately (p > 0.05). The corresponding data are summarized in (Table 3). All observed correlation coefficients were weak, and their corresponding 95% confidence intervals consistently crossed zero, indicating a lack of statistically and clinically meaningful associations.

Table 3.

Correlation between post-void residual urine volume and KHQ scores (with 95% Confidence Intervals)

		All patients n = 70 Post-void residual urine volume	Group Asymptomatic n = 40 Post-void residual urine volume	Group Symptomatic n = 30 Post-void residual urine volume
KHQ - General Health Perception	Correlation Coefficient %95 CI (p value)	-0,103 (-0,33 − 0,14) p = 0,396	-0,151 (-0,32 − 0,17) p = 0,351	0,007 (-0,36 − 0,37) p = 0,970
KHQ - Incontinence Impact		-0,070 (-0,30 − 0,17) p = 0,564	-	-0,153 (-0,48 − 0,23) p = 0,418
KHQ - Role Limitations		-0,061 (-0,29 − 0,18) p = 0,616	-0,010 (-0,32 − 0,30) p = 0,953	-0,090 (-0,43 − 0,27) p = 0,637
KHQ - Physical Limitations		-0,031 (-0,26 − 0,21) p = 0,797	-0,028 (-0,34 − 0,29) p = 0,861	-0,010 (-0,38 − 0,36) p = 0,960
KHQ - Social Limitations		-0,020 (-0,25 − 0,22) p = 0,867	-	-0,016 (-0,38 − 0,35) p = 0,932
KHQ - Personal Relationships		-0,009 (-0,24 − 0,23) p = 0,942	-	-0,006 (-0,37 − 0,36) p = 0,973
KHQ - Emotions		-0,049 (-0,28 − 0,19) p = 0,688	-0,040 (-0,35 − 0,28) p = 0,807	-0,052 (-0,41 − 0,31) p = 0,790
KHQ - Sleep/Energy		0,017 (-0,22 − 0,25) p = 0,891	-0,036 (-0,34 − 0,29) p = 0,826	0,145 (-0,24 − 0,49) p = 0,446
KHQ - Severity Measures		-0,103 (-0,33 − 0,14) p = 0,396	-	-0,179 (-0,50 − 0,21) p = 0,344
KHQ - Total Score		-0,083 (-0,31 − 0,16) p = 0,494	-0,135 (-0,41 − 0,18) p = 0,405	-0,074 (-0,42 − 0,30) p = 0,698

Discussion

The present study explored the relationship between post-void residual (PVR) urine volume and patient-reported urinary symptoms in postmenopausal women without urinary incontinence or pelvic organ prolapse. No statistically significant association was detected between PVR volume and symptom burden. However, these findings should be interpreted cautiously, as the highly selective inclusion criteria resulted in a relatively homogeneous and low-risk cohort with limited variability in both residual urine volume and symptom severity. While this design minimized potential confounding factors and allowed evaluation of PVR in a non-pathological population, it may also have reduced the ability to detect subtle or clinically meaningful associations. Therefore, the absence of a detected association should not be interpreted as definitive evidence against a potential relationship between bladder emptying and symptom burden, particularly beyond the relatively narrow physiological range represented in this study population.

The study population consisted of clinically stable postmenopausal women without significant comorbidities, prior pelvic surgery, or medications known to affect lower urinary tract function. This homogeneity allowed a more focused evaluation of bladder emptying parameters in a relatively non-pathological population.

Estrogen deficiency during the postmenopausal period has been associated with structural and functional changes in the lower urinary tract and pelvic floor due to the presence of estrogen receptors in urethral, bladder, and vaginal tissues [13–18]. Consequently, postmenopausal women may experience a wide spectrum of urinary symptoms, including frequency, urgency, dysuria, recurrent urinary tract infections, urinary incontinence, and pelvic organ prolapse. Age-related alterations in pelvic floor support and connective tissue integrity may further contribute to these symptoms.

Although none of the participants had urinary incontinence or pelvic organ prolapse, 42.9% reported mild-to-moderate urinary symptoms. Reported prevalence rates of non-incontinence urinary symptoms in postmenopausal women vary across studies, but many investigations report frequencies approaching 50% [19, 20]. Therefore, the prevalence observed in the present cohort appears broadly consistent with the existing literature.

To evaluate the impact of urinary symptoms on quality of life, the King’s Health Questionnaire (KHQ) was administered to all participants [11, 12]. Overall KHQ scores were relatively low, indicating limited quality-of-life impairment within the cohort. Given the absence of urinary incontinence and pelvic organ prolapse, these findings were expected and further support the clinically mild nature of symptoms in the study population.

Uroflowmetry findings generally suggested preserved voiding function within the study population. Mean voided volume and mean urine flow rate were within commonly accepted physiological ranges [21–24], indicating adequate bladder emptying and detrusor activity. Although average voiding time was relatively prolonged, this finding may reflect age-related changes in pelvic floor dynamics or cautious voiding behavior in postmenopausal women, even in the absence of overt lower urinary tract dysfunction.

Maximum urine flow rates were higher than commonly reported reference ranges. However, maximum flow rate is partially effort-dependent and may be influenced by abdominal straining, voided volume variability, and individual voiding dynamics. In addition, the carefully selected nature of the study cohort—excluding women with pelvic floor disorders, systemic disease, or prior pelvic surgery—may have contributed to relatively preserved outlet function and bladder contractility. Importantly, elevated maximum flow rates in the absence of obstructive symptoms are not generally considered pathological.

The mean post-void residual (PVR) urine volume observed in this study was 38.7 mL, remaining below the generally accepted upper limit of 50–100 mL [25], and suggesting preserved bladder emptying in this relatively low-risk cohort. The absence of urinary incontinence, pelvic organ prolapse, and major comorbidities likely contributed to the low and narrowly distributed PVR values observed across participants. Under such physiological conditions, minor variations in residual urine volume may not necessarily translate into clinically perceptible urinary symptoms or measurable quality-of-life impairment. Furthermore, the limited variability of PVR measurements may have reduced the statistical ability to detect meaningful associations between residual urine volume and patient-reported symptom burden.

When the cohort was divided into two groups based on the presence of voiding symptoms other than incontinence, no statistically significant differences were found in demographic characteristics. However, as expected, King’s Health Questionnaire scores were significantly higher in patients with voiding symptoms, except in the ‘Interpersonal Relationships’ domain. This suggests that even in the absence of incontinence, voiding-related complaints can negatively impact quality of life, particularly in physical, emotional, and functional domains.

As symptom classification was based on a global KHQ impact item, differences in KHQ domain scores between groups likely reflect internal consistency of perceived urinary burden rather than independent validation of symptom severity.

Despite these quality of life differences, no statistically significant differences were observed in uroflowmetry parameters between the symptomatic and asymptomatic groups. This indicates that objective voiding function, as measured by uroflowmetry and PVR volume, may not differ markedly between postmenopausal women with and without mild to moderate voiding complaints, provided incontinence is not present. This outcome may be explained by the relatively mild symptom severity in the affected group, which appears insufficient to produce measurable changes in uroflowmetry metrics.

Although impaired bladder emptying is generally expected to negatively affect urinary symptoms and quality of life, no statistically significant association was observed between post-void residual urine volume and King’s Health Questionnaire scores in the present cohort. This finding may be related to the overall mild symptom burden, low and narrowly distributed PVR values, and the absence of urinary incontinence or pelvic organ prolapse within the study population. Previous studies have similarly demonstrated limited correlation between subjective lower urinary tract symptoms and objective voiding parameters, supporting the concept that symptom perception and measurable functional findings may represent partially independent domains [26, 27]. Variability in patient selection, underlying pathophysiology, and outcome measures may further contribute to this dissociation. Our findings therefore support the interpretation that mild urinary symptoms in relatively healthy postmenopausal women may not necessarily reflect impaired bladder emptying. Similar discrepancies between objective findings and patient-reported outcomes have also been described in broader urogynecological populations, including studies involving surgical pelvic floor interventions [26].

Although the King’s Health Questionnaire is a validated and widely accepted instrument, it was primarily designed to assess quality of life in women with urinary incontinence. As such, its sensitivity in detecting and characterizing non-incontinence-related voiding symptoms may be limited. This conceptual discrepancy between an objective bladder emptying parameter (PVR) and a predominantly incontinence-focused quality-of-life instrument may have contributed to the absence of a detected association in the present study. Future studies using voiding-specific symptom instruments may provide a more accurate assessment of the relationship between bladder emptying and lower urinary tract symptoms in postmenopausal women.

Strengths and limitations

A major strength of this study is the homogeneity of the patient population. Participants had no significant medical or surgical history and were not using medications known to influence lower urinary tract function. By excluding women with urinary incontinence and/or pelvic organ prolapse, the study focused on a narrowly defined cohort of asymptomatic or mildly symptomatic postmenopausal women, allowing a clearer evaluation of the relationship between post-void residual (PVR) volume and urinary symptoms in a non-pathological setting.

Nevertheless, several important limitations should be acknowledged. First, although the study was prospectively designed, its analytical structure is cross-sectional, and therefore causal relationships cannot be established.

Second, no a priori sample size or power calculation was performed. Given the relatively small sample size, the limited variability in PVR values, and the generally mild symptom burden, the study may have been underpowered to detect clinically meaningful associations. Consequently, the absence of statistically significant findings should be interpreted as limited precision rather than definitive evidence of no relationship.

Third, symptom characterization relied on the King’s Health Questionnaire, which is primarily designed for urinary incontinence and may not adequately capture voiding-phase symptoms such as hesitancy, straining, weak stream, or incomplete emptying. In addition, symptom grouping based on a single KHQ item may have introduced misclassification bias and limited construct validity.

Another important limitation relates to the variability in voided volumes and the lack of standardized bladder filling conditions.In addition, PVR measurements were based on a single assessment rather than repeated measurements. Given the known physiological variability of residual urine volume, this approach may have introduced random measurement error and reduced the ability to detect subtle associations.

Since both uroflowmetry parameters and PVR are volume-dependent, this heterogeneity may have introduced measurement bias and reduced comparability across participants.

Furthermore, the statistical analysis was limited to bivariate correlations, and no multivariable adjustments were performed for potential confounders such as age, body mass index, parity, or voided volume.

Finally, the highly selective inclusion criteria resulted in a relatively healthy and homogeneous study population. While this approach reduced confounding, it also limits the generalizability of the findings to broader urogynecological populations.

Taken together, these limitations indicate that the present findings should be interpreted as exploratory and hypothesis-generating. The absence of a detected association does not necessarily imply the absence of a clinically meaningful relationship, particularly in the context of methodological constraints and limited variability within the study parameters.

Conclusion

In this exploratory cohort of postmenopausal women without urinary incontinence or pelvic organ prolapse, no statistically significant association was detected between post-void residual urine volume and patient-reported urinary symptoms. However, given the limited sample size, restricted variability of PVR measurements, and methodological constraints, these findings should be considered exploratory rather than definitive. Further adequately powered and methodologically standardized studies are needed to better clarify the clinical relevance of PVR in this population.

Abbreviations

PVR

Post-void residual

KHQ

King’s Health Questionnaire

BMI

Body Mass Index

TAUS

Transabdominal Ultrasonography

Authors' contributions

KU: Data Collection, Manuscript writing. OD: Project development, Data collection, Statystical analysis, Manuscript writing.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Data availability

The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

Ethical approval was obtained from the Karadeniz Technical University Faculty of Medicine Scientific Research Ethics Committee (Protocol No: 2022/22, April 14, 2022). Written informed consent was obtained from all participants prior to enrollment. The study was conducted in accordance with the Declaration of Helsinki.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.