Objectives: Pelvic pain is a common presenting complaint at gynecologic office visits and ultrasonography is the imaging modality of choice for the female pelvis. However, the clinical utility of ultrasonography for the assessment of women with pelvic pain in the outpatient setting has not been well described. The objective of this study is to describe the findings on pelvic ultrasound in young women undergoing evaluation for pelvic pain.

Methods: A retrospective chart review identified all female patients 30 years or younger who underwent pelvic sonography in an American Institute of Ultrasound in Medicine (AIUM) certified ambulatory unit for the indication of “pelvic pain” or “dyspareunia” from January 2018 to January 2020 at a safety net hospital in Denver, CO. Ultrasounds were categorized as normal, abnormal, or indeterminate. Prevalence was calculated as the percentage of patients with abnormal ultrasound findings. The relationship between abnormal ultrasound findings and demographic variables was also assessed.

Results: 195 patients were included, of whom 5.6% had abnormal ultrasound findings. Six patients had adnexal masses (3.1%), two patients had pelvic adhesions (1.0%), two patients had uterine anomalies (1.0%), and one patient had fibroids (0.5%). There were no differences in demographic characteristics between patients with normal and abnormal or indeterminate ultrasound findings.

Conclusions: The prevalence of ultrasound abnormalities in young women with non-acute pelvic pain evaluated in the outpatient setting is low. In a safety net hospital setting with limited resources, providers should consider alternative methods of evaluation prior to utilizing pelvic ultrasound in this clinical scenario.

Pelvic pain; Dyspareunia; Pelvic ultrasound; Adnexal masses

AIUM: American Institute of Ultrasound in Medicine; ACOG: American College of Obstetricians and Gynecologists

Pelvic pain is the single most common presenting complaint at gynecologic office visits and is thought to be the indication for about 40% of laparoscopies and 10-15% of hysterectomies [1]. Ultrasonography is the imaging modality of choice for the female pelvis as it is widely available, non-invasive, relatively inexpensive, does not use ionizing radiation, and is able to wellcharacterize the pelvic organs [2]. However, the clinical utility of ultrasonography for the assessment of young women with pelvic pain in the outpatient setting has not been well described. The American College of Obstetricians and Gynecologists (ACOG) does not routinely recommend imaging in the evaluation of non-acute pelvic pain, but rather suggests that laboratory and imaging tests should be tailored to the individual after a thorough history and physical exam [3]. In a safety-net academic integrated healthcare system, the authors have noted that pelvic ultrasound is often ordered as a first-line assessment tool for the evaluation of non-acute pelvic pain. While there may be structural causes of pain, such as uterine fibroids, adnexal masses, adenomyosis, or uterine anomalies, these are relatively uncommon in young patients [4-6]. This brings into question the utility of ultrasound as a means of evaluation in these patients. The objective of this study is to describe the findings on pelvic ultrasound in young women undergoing evaluation for pelvic pain.

This was a cross-sectional study. Approval was obtained from the Quality Improvement Committee; as this study does not constitute human subject research, informed consent was not required. A retrospective chart review was performed to identify all female patients 30 years or younger who underwent pelvic sonography in our AIUM-certified ultrasound unit at Denver Health Medical Center, a safety-net academic hospital, for the indication of “pelvic pain” or “dyspareunia” from January 2018 to January 2020. This study was intended to be pragmatic and relied on the referring provider’s diagnosis of pelvic pain. Patients were excluded if they had a previously documented abnormal ultrasound, a history of surgical management of an adnexal mass, a documented history of endometriosis, were pregnant, or were referred for pain in conjunction with an intrauterine device position check. Three-dimensional ultrasound was performed if a uterine anomaly was suspected. In our practice, patients endorsing acute pelvic pain are most often evaluated in the emergency department and are, therefore, not included in this sample.

Ultrasounds were performed by specialist gynecologic sonographers and read by experts in gynecologic ultrasound. Ultrasounds were categorized as normal, abnormal, or indeterminate. We defined an abnormal ultrasound as one demonstrating one or more fibroids greater than or equal to 3 cm; adnexal masses, including physiologic ovarian cysts greater than or equal to 5 cm or any size non-physiologic cyst; adenomyosis; uterine anomalies, including bicornuate uterus, septate uterus, and didelphys uterus; or pelvic adhesions. Indeterminate ultrasounds included those for which the interpretation was unclear on physiologic or non-physiologic ovarian cysts. These ultrasounds were reviewed again by two experts in gynecologic ultrasound and re-categorized as normal or abnormal with the exception of three studies which remained indeterminate. For patients with an abnormal or indeterminate ultrasound, the authors caucused and performed image and chart review to determine whether the ultrasound findings demonstrated “low,” “possible,” or “high” likelihood of being the etiology of the patient’s pain.

For this cross-sectional study, assuming a prevalence of abnormal ultrasounds of 15% in this population, precision of 5%, and α=0.05, we aimed to identify 196 patients to include in our analysis. Prevalence was calculated as the percentage of patients with abnormal ultrasound findings. The relationship between abnormal ultrasound findings and demographic variables was assessed using Wilcoxon rank sum tests for continuous variables and chi-square and Fisher’s exact tests for categorical variables. All statistical analyses were performed with STATA software version 15.0 (College Station, Texas).

A total of 309 pelvic ultrasounds were performed in this population over the two-year period of the study. Of these, 104 were excluded as illustrated in Figure 1. The remaining 195 patients were included in the final analysis. Transvaginal ultrasound was performed in 186 patients (95.4%) and transabdominal ultrasound was performed in nine patients (4.6%). The indication for the ultrasound was pelvic pain in 162 patients (83.1%), dyspareunia in 21 patients (10.8%), and both pelvic pain and dyspareunia in 12 patients (6.2%). Demographic characteristics are shown in Table 1.

We identified a total of 11 abnormal ultrasounds for a prevalence of 5.6%. The abnormal findings are further categorized in Table 2. We also identified three indeterminate ultrasounds, making the prevalence of abnormal or indeterminate ultrasounds 7.2%. There were no significant differences in age, parity, body mass index (BMI), ethnicity, or previous normal ultrasounds between patients with normal ultrasound findings and those with abnormal or indeterminate ultrasound findings. Despite the fact that structural abnormalities are relatively uncommon in young women, as demonstrated here, these patients are frequently referred for pelvic ultrasound as an initial step in the evaluation of non-acute pelvic pain.

Furthermore, even in patients with abnormal ultrasound findings, the ultrasound results were felt to be unlikely to explain their pelvic pain. Table 3 describes the findings in the abnormal and indeterminate ultrasounds as well as the likelihood of the clinical correlation with the patient’s pain symptoms. For example, the ultrasound for patient #3 demonstrated a 1.5 cm left adnexal mass, which is unlikely to explain the clinical symptoms of suprapubic cramping and urinary frequency. Conversely, the ultrasound for patient #8 demonstrated an 11.1 cm left ovarian dermoid, which is very likely to cause dyspareunia. In total, we identified four patients (2.1%) for which the ultrasound findings were highly likely to explain the clinical symptoms.

The majority of patients in our study had a normal pelvic ultrasound. Although we identified 14 abnormal or indeterminate ultrasounds, even fewer of these abnormal ultrasounds were likely to demonstrate the etiology of the patient’s presenting complaint. Our findings are consistent with those previously published. In the Nurses Health Study II, Marshall et al., found an incidence of fibroids diagnosed by hysterectomy, ultrasound, or pelvic exam of 4.3 per 1000 person-years in women ages 25- 29, compared to 14.7 per 1000 person-years in women ages 35- 39 and 22.5 per 1000 person years in women ages 40-44 [4]. Similarly, Yu et al., demonstrated a prevalence of adenomyosis of 0.3% in women age 26-30 compared to 1.5% in women age 41-45 [5]. Given the very low prevalence of these structural abnormalities in young women compared to older women, these findings are unlikely to explain non-acute pelvic pain symptoms in this population.

Many providers may feel that a pelvic ultrasound is a benign test. However, there are associated costs, including utilization of resources and the invasive nature of transvaginal ultrasound. Given the low yield of pelvic ultrasound in women age 30 or younger with non-acute pelvic pain, the authors would suggest performing a thorough physical exam to assess for symptoms of pelvic floor dysfunction, which is much more common and affects up to 25% of this population [7,8]. In a safety net hospital setting with limited resources, our suggestion would be to utilize pelvic ultrasound only for those for whom other etiologies cannot be identified. Further studies are needed to determine if there is a subset of young patients who would benefit from ultrasound as the initial diagnostic test.

To our knowledge, this is the first study to evaluate the clinical utility of ultrasonography for the assessment of young women with non-acute pelvic pain. Strengths of our study include a large sample size of nearly 200 patients with imaging performed in a specialized gynecologic ultrasound unit with clinical faculty who are experts in gynecologic ultrasound. Given that it is an integrated healthcare system, we were able to complete chart reviews on those patients with abnormal findings. This was a pragmatic study looking at referral indication for ultrasound, therefore providing good clinical application. However, a limitation of our study is that we did not use strict criteria for the diagnosis or definition of pelvic pain. Additionally, the correlation between ultrasound findings and the clinical picture were inherently subjective.

Table 1: Demographics, presented as n (%) or median (range).

Table 2: Abnormal ultrasound results.

Table 3: Correlation of ultrasound results and clinical indication.

We have demonstrated that the prevalence of ultrasound abnormalities in young women with non-acute pelvic pain is low and thus the clinical utility of pelvic ultrasound for initial evaluation in this population is also low. In our safety net integrated healthcare system, we will be using these findings to avoid utilizing pelvic ultrasound in the initial evaluation of these patients.

1. Gelbaya TA, El-Halwagy HE. Focus on primary care: chronic pelvic pain in women. Obstetrical & gynecological survey. 2001; 56: 757- 764.

2. Derchi LE, Serafini G, Gandolfo N, Gandolfo NG, Martinoli C. Ultrasound in gynecology. Eur radiol. 2001; 11: 2137-2155.

3. American College of Obstetricians and Gynecologists. Chronic Pelvic Pain: ACOG Practice Bulletin, Number 218. Obstetrics and gynecology. 2020; 135: e98-e109.

4. Marshall LM, Spiegelman D, Barbieri RL, Goldman MB, Manson JE, Colditz GA, et al. Variation in the incidence of uterine leiomyoma among premenopausal women by age and race. Obstet Gynecol. 1997; 90: 967-973.

5. Yu O, Schulze-Rath R, Grafton J, Hansen K, Scholes D, Reed SD. Adenomyosis incidence, prevalence and treatment: United States population-based study 2006-2015. Am J Obstet Gynecol. 2020; 223: 94.e1-.e10.

6. Saravelos SH, Cocksedge KA, Li TC. Prevalence and diagnosis of congenital uterine anomalies in women with reproductive failure: a critical appraisal. Hum Reprod Update. 2008; 14: 415-429.

7. Reiter RC, Gambone JC. Nongynecologic somatic pathology in women with chronic pelvic pain and negative laparoscopy. J Reprod Med. 1991; 36: 253-259.

8. Tu FF, As-Sanie S, Steege JF. Prevalence of pelvic musculoskeletal disorders in a female chronic pelvic pain clinic. J Reprod Med. 2006; 51: 185-189.