Predictors of Procedural Pain in Office Hysteroscopy

Introduction

Hysteroscopy is an indispensable tool in modern obstetrics and gynecology, allowing direct visualization of the uterine cavity for both investigative and therapeutic purposes [1]. It is particularly useful in the evaluation of abnormal uterine bleeding, uterine anomalies, retained intrauterine devices, and intrauterine pathology in infertile patients [1,2]. Unlike indirect imaging modalities, hysteroscopy allows real-time assessment of endometrial surfaces and submucosal lesions. Furthermore, biopsies and even therapeutic interventions can be performed during procedures [3].

Traditionally, transvaginal ultrasonography (TVUS) and saline infusion sonohysterography (SIS) are the first options when investigating uterine pathologies [4]. TVUS is widely available and cost-effective, but it has limited sensitivity for small or flat endometrial lesions [5]. SIS improves endometrial cavity distension and lesion detection, but its reliance on interpretation of fluid-tissue interfaces is a restriction that can affect diagnostic accuracy [6]. Today, hysteroscopy has become a gold standard imaging modality in the field, providing direct visualization that, when combined with histopathological examination, achieves excellent accuracy in characterizing benign, premalignant, and malignant intrauterine lesions [1,2,4].

Hysteroscopy is often performed without the need for general anesthesia and as an in-office procedure in many clinical settings [7]. The procedure can be completed within minutes, facilitates the possibility of biopsy sampling, is considered to cause minimal discomfort, and eliminates hospital admission and the risks associated with anesthesia [7,8]. Despite these advantages, evidence shows that pain is the principal limitation of office hysteroscopy [9]. Discomfort experienced during cervical passage, uterine distension, and instrument manipulation can lead to poor tolerance, incomplete examinations, and procedure failure [9]. Various strategies have been explored to mitigate pain, including oral or local analgesia, modified cervical dilation techniques, and patient positioning, but there is no consensus on the most effective approach, and understanding patient- and procedure-related factors that contribute to pain levels is essential to optimize pain prevention and ensure procedural success [10]. Poorly controlled pain reduces patient satisfaction and willingness to undergo repeat procedures while increasing the risk of incomplete examinations. As office-based gynecological procedures become increasingly common, developing effective pain management strategies has emerged as an important clinical goal. Identifying which patients and procedural factors are associated with greater discomfort is key to improving outcomes and patient experience.

Although pain during office hysteroscopy has been studied extensively, findings remain inconsistent about which anatomical and obstetric factors best predict pain intensity. Few studies have examined how multiple risk factors interact within the same patient population. The aim of this study was to quantify pain levels during office hysteroscopy using a visual analogue scale (VAS) and to identify independent risk factors associated with increased pain. By examining demographic characteristics, cervical anatomy, procedural variables, and analgesic interventions, we sought to develop evidence-based recommendations for minimizing discomfort and enhancing patient satisfaction in the practice of office hysteroscopy.

Material and Methods

ETHICAL ISSUES:

This study was conducted in compliance with the ethical principles of the Declaration of Helsinki and national regulations. Ethical approval was obtained from the Ethics Committee of the University of Health Sciences, Istanbul Kanuni Sultan Süleyman Training and Research Hospital (decision number: #148, dated July 22, 2020). The study protocol was also approved by the Dean’s Office of the University of Health Sciences. Written informed consent was obtained from all participants after providing detailed verbal and written explanations regarding the study. Patient data were anonymized and stored in secure, password-protected databases accessible only to the research team. Participants were informed they could withdraw at any time without affecting their care, and no financial compensation was offered.

STUDY DESIGN AND PARTICIPANTS:

This was a prospective observational study conducted at the Department of Obstetrics and Gynecology, University of Health Sciences, Kanuni Sultan Süleyman Training and Research Hospital, Istanbul, Turkey. The study was carried out between August 15, 2020, and October 15, 2020. All consecutive patients meeting inclusion criteria during the study period were enrolled using a convenience sampling approach

The study population consisted of women aged 18 to 70 years who presented with various gynecological concerns and underwent office hysteroscopy during the study period. Exclusion criteria were: patients younger than 18 or older than 70 years; patients with a thin and regular endometrial lining without intracavitary lesions; women with severe psychiatric disorders or sensory impairments such as visual or auditory deficits (due to the inability to assess pain using VAS); patients with suspected gynecologic malignancies; and those with a serum beta-hCG level above 5.3 mIU/mL. We excluded patients over age 70 years because of the higher prevalence of comorbidities and age-related anatomical changes that might confound pain assessment. Women with thin, regular endometrial lining without intracavitary lesions did not meet current clinical indications for hysteroscopy and were therefore excluded. We also excluded those with suspected malignancy to avoid delaying definitive treatment and because cancer-related anxiety could affect pain perception.

The clinical indication for office hysteroscopy was classified into predefined categories: abnormal uterine bleeding, increased endometrial thickness, suspected endometrial polyp or myoma, infertility, amenorrhea/oligomenorrhea, and suspicion of intrauterine foreign body. These indications were determined in accordance with current ACOG and ESGE (European Society for Gynaecological Endoscopy) guidelines. Patients with a history of hysteroscopy were also identified and categorized.

The sample size of 102 patients was determined based on feasibility within the study period. This sample provides adequate statistical power (>80%) to detect moderate effect sizes in multivariable regression analysis with up to 8 predictors (α=0.05).

BASELINE CLINICAL AND DEMOGRAPHIC DATA:

Age was recorded and height and weight were measured on the day of the procedure using a standardized digital stadiometer and scale. Body mass index (BMI) was calculated using the standard formula: weight in kilograms divided by the square of height in meters (kg/m²).

Medical history, including chronic systemic diseases (eg, diabetes mellitus, hypertension, thyroid disorders, coronary artery disease), was obtained from patients and verified using medical records. History of anxiety or panic disorder was confirmed by documented psychiatric diagnosis.

Menopausal status was classified as premenopausal or postmenopausal based on menstrual history and hormonal profile if necessary. Obstetric history, including gravidity, parity, number of abortions, previous cesarean deliveries, curettage, and mode of delivery (vaginal, cesarean, both, or none), was recorded. The uterine position was determined via bimanual pelvic examination and confirmed using TVUS. The presence of Müllerian anomalies, chronic pelvic pain, dysmenorrhea, and dyspareunia was assessed based on clinical history and physical examination. Dysmenorrhea was defined as cyclic lower abdominal or pelvic pain associated with menstruation, and dyspareunia as pain during or after sexual intercourse, consistent with the definitions of the American College of Obstetricians and Gynecologists (ACOG) [11].

HYSTEROSCOPY PROCEDURE AND TECHNICAL PARAMETERS:

All office hysteroscopies were performed by the same experienced gynecologist using a 4-mm diameter, 30-degree rigid hysteroscope (Olympus C-170 series) in a standard manner. The procedures were performed in the dorsal lithotomy position using a no-touch technique to access the cervical canal without the use of a speculum or tenaculum unless necessary. The uterine cavity was distended using isotonic saline solution under continuous flow, with intrauterine pressure maintained at approximately 80 mmHg using a hysteroscopic pump system. Hysteroscopy was planned during the early proliferative phase in premenopausal women (within the first 10 days of the menstrual cycle) and after the cessation of bleeding in postmenopausal women.

Surgeries such as polypectomy or adhesiolysis were recorded. The use of adjunct instruments such as speculum, tenaculum, or cervical dilators was noted. When administered, vaginal misoprostol 400 mcg was given 3 to 4 hours before the procedure as per institutional protocol. The total duration of the hysteroscopy procedure, defined as the time from insertion to removal of the hysteroscope, was measured in minutes.

VITAL SIGNS AND PAIN ASSESSMENT:

Vital signs, including body temperature, heart rate, systolic and diastolic blood pressure, and respiratory rate, were recorded at 3 time points: 15 minutes before the procedure, during the procedure, and 15 minutes after the procedure. All measurements were performed by a trained nurse using calibrated medical equipment.

Before the procedure, all patients received verbal instructions on using the VAS with a visual demonstration of the scale. They were asked to mark their pain level on a 10-cm line ranging from 0 (no pain) to 10 (worst imaginable pain). Each patient was asked to rate her pain level 15 minutes before and 15 minutes after the hysteroscopy. The intra-procedural pain score, representing the peak pain experienced during the intervention, was also recorded immediately after the procedure by asking the patient to retrospectively rate her experience.

ENDPOINTS:

The primary outcome was pain intensity during office hysteroscopy, assessed by VAS score immediately after the procedure. We examined patient demographic characteristics (age, BMI, menopausal status), obstetric history (parity, vaginal delivery, cesarean sections), anatomical features (uterine position, Müllerian anomalies), and procedural factors (duration, instrument use, operative interventions) as potential predictors. Secondary outcomes were vital sign changes measured before, during, and after the procedure.

STATISTICAL ANALYSIS:

All analyses were conducted using IBM SPSS version 27.0 (IBM Corp., Armonk, NY, USA). P<0.05 values were accepted as statistically significant results. Histogram and Q-Q plots were used to determine whether variables are normally distributed. Descriptive statistics are presented using mean±standard deviation for normally distributed continuous variables, median (25^th–75^th percentile) for non-normally distributed continuous variables and frequency (percentage) for categorical variables. Before, during and after intervention measurements were analyzed using repeated measures analysis of variance (ANOVA) for normally distributed continuous variables and Friedman’s ANOVA by ranks for non-normally distributed continuous variables. Between-groups analysis of VAS score was performed using a t test or one-way ANOVA depending on the number of groups. Pairwise comparisons were adjusted using Bonferroni correction method. Relationships between VAS scores and other continuous variables were evaluated using Pearson or Spearman correlation coefficients. Multivariable linear regression analysis (stepwise selection method) was performed to determine significant factors independently associated with VAS score. We used stepwise multivariable linear regression to identify independent predictors while controlling for confounding. Variables showing P<0.05 in univariate analysis were entered into the multivariable model. We verified standard model assumptions (linearity, normality of residuals, homoscedasticity, and absence of multicollinearity). There were no missing data for the primary outcome or key predictors. Statistically significant variables according to univariate analysis results were included in linear regression analysis.

Results

We evaluated demographic, obstetric, anatomical, and procedural variables in 102 women to identify independent predictors of pain during office hysteroscopy. A total of 102 women with a mean age of 41.62±7.94 years were included in the study. The median duration of office hysteroscopy was 5 minutes (IQR 4–10). Pain during the procedure, assessed by VAS score, averaged 4.91±2.97. Other demographic and clinical characteristics are summarized in Table 1.

Heart rate showed significant variation (P<0.001), increasing from baseline during the procedure and then decreasing after the intervention. Systolic (P<0.001) and diastolic blood pressure (P<0.001) demonstrated significant changes, with elevations during the procedure followed by post-procedure reductions. Respiratory rate also showed statistically significant alterations (P<0.001), increasing during the intervention before returning toward baseline levels (Table 2).

Patients without vaginal birth history reported significantly higher pain scores than those with vaginal deliveries (P<0.001) (Figure 1). Uterine position significantly influenced pain levels (P<0.001), with retroverted uteri associated with the most discomfort, followed by anteverted and normal positions (Figure 2, Table 3). These findings suggest that anatomical deviation from the normal uterine axis, whether retroversion or anteversion, contributes to procedural difficulty and patient discomfort, likely due to suboptimal instrument trajectory and increased manipulation requirements.

A weak negative correlation was determined between BMI and pain (r=−0.203, P=0.041), but the clinical significance of this finding is limited given the small effect size. The number of cesarean sections showed a weak positive correlation with pain (r=0.197, P=0.047). Procedure duration demonstrated a moderate positive correlation with pain intensity (r=0.439, P<0.001) (Figure 3). There were no other significant correlates with pain scores (Table 4).

According to multivariable linear regression, we determined that vaginal birth (b: −1.990, 95% CI: −3.087 – −0.892, P=0.001) was independently associated with low VAS scores while retroverted uterus (b: 2.261, 95% CI: 0.620–3.902, P=0.007) and longer office hysteroscopy (b: 0.196, 95% CI: 0.063–0.330, P=0.004) were independently associated with high VAS scores. In clinical terms, the identified independent risk factors demonstrated meaningful effects on pain intensity. Patients with retroverted uterus experienced an average of 2.26 points higher VAS scores compared to those with normal uterine position (95% CI: 0.62–3.90), while each additional minute of procedure time added approximately 0.2 points to the pain score (95% CI: 0.06–0.33). Conversely, prior vaginal delivery was associated with nearly 2-point reduction in pain scores (b=−1.99, 95% CI: −3.09 to −0.89). Other variables included in the analysis, body mass index (P=0.133), number of cesarean sections (P=0.955) and uterine position (P=0.068) were non-significant (Table 5).

Discussion

LIMITATIONS:

The generalizability of our findings is limited due to study design (single-center and sample size) and possible variations in procedural protocols. We also note that patient distribution across several key clinical and demographic variables was not homogeneous, which limits the strength of subgroup analyses. Variables such as menopausal status, birth history, uterine position, and the clinical indication for hysteroscopy were unevenly represented, and some subgroups (infertility, suspected foreign body, birth history) were relatively small. Additionally, several potentially relevant variables were either rare or present in limited sample size (abortion or curettage history, chronic pelvic pain, Müllerian anomalies, prior hysteroscopy experience, and intra-procedural factors like speculum or tenaculum use, cervical dilatation, operative intervention, and misoprostol administration). As a result, their true effect on pain perception may not have been evaluated meaningfully. Finally, pain was assessed solely using the visual analog scale (VAS), which, although widely used and validated, may be affected by personal characteristics, pain threshold differences, and comprehension of the use of the scale itself. It does not account for the qualitative, emotional, or functional aspects of pain, nor for patient satisfaction or procedural tolerability.

Conclusions

Office hysteroscopy pain is influenced by a combination of anatomical, obstetric, and procedural factors. Specifically, retroverted uterine position, absence of prior vaginal delivery, prolonged procedure duration, and a higher number of cesarean deliveries were associated with greater pain perception. BMI was negatively correlated with pain, albeit weakly. Vital sign changes observed during the procedure further support the presence of a physiological stress response. Anticipating increased discomfort in patients with these risk factors may guide clinicians to implement preventive strategies such as preprocedural counseling, shorter procedure times, or tailored analgesic approaches. Future multicenter prospective studies with larger and more evenly distributed cohorts, and with inclusion of psychological and procedural variables, are warranted to further refine patient-centered protocols and improve procedural tolerance in office hysteroscopy.