Correlation between IOTA Simple Ultrasound Rules and Histopathological Findings in Adnexal Masses: A Tertiary Hospital-Based Study from Bangladesh

Background: Preoperative differentiation of benign vs malignant adnexal masses is essential for timely oncology referral and avoiding unnecessary sur- gery. We evaluated the diagnostic accuracy of the International Ovarian Tu- mor Analysis (IOTA) Simple Rules (SRs) in a tertiary oncology center in Bang- ladesh. Methods: In this prospective study, 94 consecutive patients underwent standardized transvaginal/transabdominal ultrasonography and subsequent surgery with histopathology as reference. Masses were classified per IOTA SRs as benign, malignant, or indeterminate. Diagnostic metrics were calculated for conclusive SR classifications. Results: Of 94 analyzable cases, histopathology showed 53 benign (56.4%) and 41 malignant (43.6%). SR categorization yielded 48 benign (51.1%), 38 malignant (40.4%), and 8 indeterminate (8.5%). For conclusive cases (n = 86), IOTA SRs achieved sensitivity 84.2% (95% CI 68.8 - 94.0), specificity 87.2% (74.3 - 95.1), PPV 84.2%, NPV 87.2%, and over- all accuracy 85.9% (76.6 - 92.5). The most frequent malignant features were M1 (irregular solid tumor) and M5 (very strong Doppler flow). Conclusion: IOTA SRs demonstrated robust, low- cost diagnostic performance in this ter- tiary oncology setting. Slightly lower estimates than some multicenter series likely reflect single-center design, higher malignancy prevalence, and operator variability. Larger multicenter studies in LMICs are warranted for broader val- idation. How to cite this paper: Khatoon, F., Begum, S.A., Akter, N., Parvin, M., Nahar, K., Alam, F. and Hassan, Md.R. (2025) Correlation between IOTA Simple Ultra- sound Rules and Histopathological Find- ings in Adnexal Masses: A Tertiary Hospi- tal-Based Study from Bangladesh. Open Journal of Obstetrics and Gynecology, 15, 2124-2137. https://doi.org/10.4236/ojog.2025.1512179 Received: November 27, 2025 Accepted: December 21, 2025 Published: December 24, 2025 Copyright © 2025 by author(s) and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access F. Khatoon et al. DOI: 10.4236/ojog.2025.1512179 2125 Open Journal of Obstetrics and Gynecology

Adnexal Masses, IOTA Simple Rules, Ultrasonography, Diagnostic Accuracy, Bangladesh 1. Introduction Adnexal masses are a frequent diagnostic and therapeutic challenge in gynecol- ogy, encompassing conditions ranging from functional cysts to malignant ovarian neoplasms. Globally, ovarian cancer is the most lethal gynecological malignancy, accounting for over 295,000 new cases and 185,000 deaths annually, with five-year survival rates below 30% in many low - and middle-income countries. Early dif- ferentiation of malignant from benign adnexal masses is therefore pivotal to ex- pedite referral to gynecologic oncolo gy for malignancy and avoid unnecessary radical procedures for benign disease [1]-[5]. Over the last three decades, multiple strategies have been explored to improve preoperative diagnosis. Tumor markers such as CA -125, while widely used, have limited specificity, particularly in premenopausal women [6]-[8]. Risk algorithms such as the Risk of Malignancy Index (RMI) and the OVA1 test combine CA-125, menopausal status and imaging, but are either too resource -intensive or incon- sistently validated outside high-income settings [9]-[11]. In contrast, ultrasonog- raphy remains the first-line modality for adnexal mass evaluation due to its acces- sibility, non-invasiveness and affordability. However, its diagnostic reliability has traditionally been undermined by operator dependence and lack o f standardized interpretation criteria. To address these limitations, the International Ovarian Tumor Analysis (IOTA) group developed standardized ultrasound terminology and the widely used IOTA Simple Rules (SRs) comprising five benign (B) and five malignant (M) features. In a large multicenter prospective validation (~2,000 patients, 19 centers), SRs showed excellent discrimination (sensitivity 92%, specificity 96%) with conclusive

for ~77% of masses; adding expert judgment for inconclusive cases main- tained strong performance (91% sensi tivity, 93% specificity) [12] [13]. As the IOTA framework matured, the three -step strategy— simple descriptors → SRs → expert review— enabled non-expert sonographers to classify ~84% of masses us- ing the first two steps, achieving sensitivity 95.2%, specificity 97.7%, and accuracy 97.2% on ex ternal validation; a recent meta- analysis similarly reported pooled sensitivity and specificity near 94% [14] [15]. Regional evidence from Asia supports clinical utility. A large Indian study found that IOTA SR and the ADNEX model achieved high diagnostic accuracy (~91%) and outperformed RMI 4; O -RADS showed the highest sensitivity (98%) while ADNEX provided the highest specificity (93%) [16]. According to GLOBOCAN 2022, Bangladesh recorded an estimated 2,846 new ovarian cancer cases and 1,857 deaths, underscoring the need for accurate, low - F. Khatoon et al. DOI: 10.4236/ojog.2025.1512179 2126 Open Journal of Obstetrics and Gynecology cost triage tools such as the IOTA Simple Rules [17] [18]. Preliminary national data from Chittagong Medical College Hospital (n = 45) showed IOTA SRs out- performing RMI 4 (accuracy 93.3% vs 73.3%) [19] [20]. Taken together, global validation, Asian data, and early Bangladeshi experience highlight the diagnostic accuracy and feasibility of IOTA SRs. Yet adequately pow- ered, tertiary oncology– based Bangladeshi studies remain scarce, particularly re- garding the indeterminate group that challenges decision-making. Therefore, this study evaluated the diagnostic accuracy of IOTA Simple Ultrasound Rules against histopathology in a tertiary oncology hospital in Bangladesh, estimating sensitiv- ity, specificity, PPV, NPV, and outcomes of inconclusive cases, and describing the histopathological spectrum of adnexal masses in this cohort. 2. Materials and Methods 2.1. Study Settings This study was conducted at the Department of Gynecologic Oncology, Bangla- desh Medical University, Shahbagh, Dhaka. Patients presenting with suspected adnexal masses to the outpatient and inpatient departments of Gynecologic On- cology and Obstetrics & Gynaecology units were included. 2.2. Study Design A prospective, cross-sectional study design was employed to evaluate the diagnos- tic performance of the IOTA Simple Ultrasound Rules in distinguishing benign from malignant adnexal masses, using histopathological diagnosis as the reference standard. 2.3. Study Procedure Ethical approval was obtained from the Institutional Review Board (IRB) of Bang- ladesh Medical University before commencing the study. A total of 94 consecutive patients with clinically suspected adnexal masses, fulfilling inclusion criteria, were recruited from outpatient and inpatient departments. Written informed consent was obtained after explaining the study objectives, procedures, and voluntary par- ticipation. Each participant underwent transvaginal ultrasonography (TVS) using either a Voluson P8 or Philips ultrasound machine. Ultrasound examinations followed the standardized guidelines of the IOTA group (Timmerman et al., 2008). When TVS was insufficient due to mass size or position, transabdominal ultrasonography was performed. The IOTA Simple Ultrasound Rules were applied to classify adnexal masses based on specific sonographic features. A mass was classified as benign if one or more benign features were present without any malignant features, malignant if one or more malignant features were present without benign features, and incon- clusive if both benign and malignant features coexisted or if none of the defined features were identified. F. Khatoon et al. DOI: 10.4236/ojog.2025.1512179 2127 Open Journal of Obstetrics and Gynecology Malignant features (M -Rules) included: irregular solid tumors (M1), ascites (M2), four or more papillary projections (M3), irregular multilocular solid tumors ≥100 mm (M4), and very strong blood flow (color score 4, M5). Benign features (B-Rules) included: unilocular cysts (B1), solid components <7 mm (B2), acoustic shadows (B3), smooth multilocular tumors <100 mm (B4), and absent detectable blood flow (color score 1, B5). All participants underwent surgical removal of the adnexal mass within 120 days of ultrasound assessment. The surgical approach— laparoscopy or laparot- omy— was based on clinical indications. Excised specimens were examined histo- pathologically, serving as the definitive diagnostic reference. Ultrasound evalua- tions and interpretations were completed before surgery and before histopatho- logical results were available to avoid bias. 2.4. Sample Size The sample size of 94 was calculated based on the estimated prevalence of ad- nexal masses, anticipated sensitivity and specificity of the IOTA rules, desired precision, and confidence levels, providing adequate power to evaluate diagnos- tic accuracy. 2.5. Data Collection Data were collected using a structured questionnaire capturing demographic details, clinical history, sonographic findings, serum CA-125 levels, and histopathological outcomes. Investigators conducted patient interviews and reviewed medical rec- ords. Confidentiality was maintained by assigning unique identification numbers, with data accessible only to the research team and used solely for this study. 2.6. Data Analysis Data were entered and analyzed using SPSS version 24. Quantitative variables were expressed as mean ± standard deviation (SD), and categorical variables as frequencies and percentages. Diagnostic performance metrics— sensitivity, speci- ficity, PPV, and NPV — were calculated against histopathological diagnosis. The proportion of inconclusive cases by IOTA and their histopathological outcomes were recorded. The distribution of final histopathological diagnoses was analyzed. Statistical significance was set at p < 0.05 with 95% confidence intervals. 2.7. Ethical Considerations The study adhered to the Declaration of Helsinki (1964) and its amendments. Written informed consent was obtained after explaining the objectives, methods, risks, and benefits. No experimental drugs or procedures beyond standard clinical care were used. Co nfidentiality and anonymity were rigorously maintained via unique identifiers, with data access restricted to the research team. The study posed no additional risks or burdens beyond routine clinical management. No conflicts of interest were declared. F. Khatoon et al. DOI: 10.4236/ojog.2025.1512179 2128 Open Journal of Obstetrics and Gynecology 3. Results 3.1. Age and Menopausal Distribution Table 1 summarizes malignancy increased with age, from 32–39% in younger groups to 63% among women older than 50 years. Postmenopausal women show higher malignancy (43.9%) than premenopausal (37%), highlighting increased risk after menopause. Table 1 . Age and menopausal distribution of respondents in benign and malignant tumor. (n = 94) Characteristics Benign (%) Malignant (%) Age Group (in Years) 10 - 30 years 23 (67.6%) 11 (32.4%) 30 - 50 years 20 (60.6%) 13 (39.4%) >50 years 10 (37.0%) 17 (63.0%) Menopausal status (n = 84) Premenopausal 17 (63.0%) 10 (37.0%) Postmenopausal 32 (56.1%) 25 (43.9%) 3.2. Sonographic Categorization of Adnexal Masses The sonographic assessment of adnexal masses using the IOTA Simple Ultra- sound Rules classified the masses into three categories. Among the 94 cases, 48 (51.1%) were categorized as benign, 38 (40.4%) as malignant, and 8 (8.5%) were inconclusive or indeterminate (Figure 1 ). Figure 1 . Sonographic categorization of adnexal mass by IOTA simple rules. 3.3. Association of the Sonographic Findings and IOTA Classification The majority of adnexal masses were unilateral across all histopathological groups, found in 95.9% of benign, 97.4% of malignant, and all (100%) indetermi- nate cases, with no statistically significant difference (p = 0.8). Bilateral involve- F. Khatoon et al. DOI: 10.4236/ojog.2025.1512179 2129 Open Journal of Obstetrics and Gynecology ment was rare. A significant association was observed in terms of locularity (p < 0.001): unilocular cysts were most frequently seen in benign cases (89.8%), while multilocular morphology predominated among malignant masses (71.1%). Re- garding consistency, cystic structures were dominant in benign tumors (79.6%), whereas malignant lesions more often exhibited mixed (50.0%) or solid (13.2%) components (p < 0.001). The presence of free fluid was another strongly discrim- inating feature, significantly more common in malignant cases (71.1%) compared to benign (8.2%) and indeterminate groups (25.0%) (p < 0.001 ) (Table 2 ). Table 2 . Association of the sonographic findings and IOTA classification among the par- ticipants. (n = 94) Characteristics Benign (n = 48) Malignant (n = 38) Indeterminate (n = 8) p-value Number Unilateral 47 (95.9%) 37 (97.4%) 8 (100.0%) 0.8 Bilateral 1 (2.0%) 1 (2.6%) 0 (0.0%) Locularity Unilocular 44 (89.8%) 11 (28.9%) 6 (75.0%) <0.001 Multilocular 4 (8.2%) 27 (71.1%) 2 (25.0%) Consistency Cystic 39 (79.6%) 14 (36.8%) 4 (50.0%) <0.001 Mixed 8 (16.3%) 19 (50.0%) 2 (25.0%) Solid 1 (2.0%) 5 (13.2%) 2 (25.0%) Free Fluid Yes 4 (8.2%) 27 (71.1%) 2 (25.0%) <0.001 No 43 (87.8%) 11 (28.9%) 6 (75.0%) 3.4. IOTA Sonography Diagnostic Performance The IOTA Simple Sonographic categorization demonstrated high diagnostic ac- curacy in differentiating benign and malignant adnexal masses when compared to histopathological diagnosis, with a sensitivity of 84.21% and specificity of 87.23%. The positive predi ctive value (PPV) was 84.21%, while the negative pre- dictive value (NPV) was 87.23%, resulting in an overall accuracy of 85.88% (Ta- ble 3). Table 3. Diagnostic accuracy of sonographic categorization compared to histopathological diagnosis. (n = 86) Diagnosis Test Sensitivity (%) Specificity (%) PPV (%) NPV (%) Accuracy (%) Sonography vs Histopathology 84.21 (68.75, 93.98) 87.23 (74.26, 95.12) 84.21 (68.75, 93.98) 87.23 (74.26, 95.12) 85.88 (76.64, 92.49) 3.5. Distribution of IOTA Ultrasound Features Among malignant features, M1 (Irregular solid tumor) was the most frequently observed, comprising 38.9% of malignant findings, followed by M5 (Very strong F. Khatoon et al. DOI: 10.4236/ojog.2025.1512179 2130 Open Journal of Obstetrics and Gynecology blood flow) at 27.8%. For benign features, B1 (Unilocular cyst) and B5 (No de- tectable blood flow (color score 1) were the predominant findings, each account- ing for 32.9% of benign feature occurrences (Figure 2 ). Figure 2 . Distribution of IOTA ultrasound features. (n = 94) 3.6. Association between Sonographic Categorization and Histopathological Diagnosis There was a statistically significant association between IOTA Simple Rules and histopathology (p < 0.001). Of sonographically malignant masses, 84.2% were ma- lignant histologically; of sonographically benign, 87.2% were benign. Indetermi- nate cases (n = 8) showed 37.5% malignant and 62.5% benign outcomes (Table 4). Table 4 . Association between sonographic categorization and histopathological diagnosis. (n = 94) Sonographic Categorization Malignant n (%) Benign n (%) Total p-value Malignant 32 (84.2) 6 (15.8) 38 <0.001 Benign 6 (12.8) 41 (87.2) 47 Indeterminate 3 (37.5) 5 (62.5) 8 Total 41 53 94 3.7. Distribution of Histopathological Diagnoses Among the 94 participants included in the study, the distribution of histopatho- logical diagnoses revealed that the majority of adnexal masses were benign. Spe- cifically, 53 cases (56.4%) were histologically confirmed as benign tumors, whereas 41 cases (43.6%) were diagnosed as malignant (Figure 3 ). F. Khatoon et al. DOI: 10.4236/ojog.2025.1512179 2131 Open Journal of Obstetrics and Gynecology Figure 3 . Histological classification of Adnexal Mass. (n = 94) 3.8. Sonographic Pattern Analysis of Inconclusive Cases Table 5 details the specific sonographic rule combinations observed among the 8 cases categorized as indeterminate by IOTA and their corresponding histopatho- logical outcomes. The most frequently observed combination was M2 + B2, found in 3 cases, two of which were benign and one malignant. Two cases exhibited the pattern B3 + M4 + M5 (acoustic shadows with irregular multilocular solid tumors and very strong blood flow), and three cases showed B3 + M4, both patterns also resulting in benign histopathological diagnoses. Table 5 . Comparison between sonographic and histopathological findings of inconclusive cases. (n = 8) Sonographic findings (IOTA rules) Frequency Histopathology Benign Malignant M2 + B2 3 2 1 B3 + M4 + M5 2 2 B3 + M4 3 3 3.9. Prevalence and Diagnostic Accuracy of Benign Sonographic Features Table 6 summarizes benign ultrasound features (n = 57) and their diagnostic yield, where “Predicted” denotes correctly identified benign cases and “Result” the total instances of each feature. B2 (solid components <7 mm) was most frequent (13 cases) and most predictive (92.3%). B1 (unilocular cyst) and B3 (acoustic shadows) each appeared in 12 cases, with predictive values of 75.0% and 83.6%, respectively. B5 (absent blood flow, color score 1) occurred in 12 cases with a 75.0% predictive value. B4 (smooth multilocular tumors <100 mm) was least pre- dictive at 50.0% (8 cases). F. Khatoon et al. DOI: 10.4236/ojog.2025.1512179 2132 Open Journal of Obstetrics and Gynecology Table 6 . Prevalence and predictive power of benign factors. (n = 57) Benign Predicted Result Percentage % B1 9 12 75. 0 B2 12 13 92.3 B3 10 12 83.6 B4 4 8 50.0 B5 9 12 75.0 Table 7 summarizes the distribution and predictive accuracy of malignant ul- trasound features. Among these, M5 (very strong blood flow, color score 4) was the most commonly observed malignant criterion, found in 16 cases with a pre- dictive accuracy of 91.2%. M1 (irregular solid tumor) and M4 (irregular multiloc- ular solid tumors ≥100 mm) were also frequent, observed in 9 and 7 cases respec- tively, with predictive accuracies of approximately 79% and 94%. Features such as M2 (ascites) showed strong predictive value exceeding 90%. Although M3 (pres- ence of four or more papillary projections) was rare in this cohort (1 case), it achieved perfect predictive accuracy of 100%. Table 7 . Prevalence and predictive power of malignant factors. (n = 38) Malignant Predicted Results Percentage % M1 7 9 78.9 M2 4 5 92.9 M3 1 1 100 M4 6 7 94.4 M5 14 16 91.2 Table 8 presents the frequency and diagnostic distribution of combined benign and malignant ultrasound features per IOTA Simple Rules in adnexal masses. Among the 94 cases analyzed, benign features B1 (unilocular cyst), B2 (solid com- ponent <7 mm), B3 (acoustic sh adows), B4 (smooth multilocular tumors <100 mm), and B5 (absent blood flow, color score 1) were recorded alongside malig- nant features M1–M5. The most frequent benign features were B2 (13 cases) and B1/B3 (12 each), while malignant features M5 (16) and M4 ( 7) were most com- mon. Overall, 53/94 (56.4%) cases were benign and 41/94 (43.6%) were malignant. Table 8 . Observed combinations of benign and malignant ultrasound features of IOTA simple rules ranked by frequency (n = 94). Applicable B factors Applicable M factors FREQ Benign Malignant Rate of Malignancy SN B1 B2 B3 B4 B5 M1 M2 M3 M4 M5 12 13 12 8 12 9 5 1 7 16 53 41 43.6% 4. Discussion The study ’s findings indicate that applying the IOTA Simple Ultrasound Rules (SR) for diagnosing adnexal masses is a credible and effective method, aligning accurately with the histopathological results. Our findings indicate that IOTA SR F. Khatoon et al. DOI: 10.4236/ojog.2025.1512179 2133 Open Journal of Obstetrics and Gynecology is useful for differentiating benign from malignant adnexal masses and will help to manage these patients, especially in Bangladesh, a country with limited access to advanced diagnostic tools. The correlation between the ultrasound features and the histopathology findings underscores the opportunity for ultrasound to be a non-invasive, low-cost option for early diagnosis and pre-operative assessment. In this tertiary oncology cohort, IOTA Simple Rules (SRs) showed robust diag- nostic performance (sensitivity 84.2%, specificity 87.2%, accuracy 85.9%) with an indeterminate rate of 8.5%. Malignancy prevalence was high (43.6%), consistent with referral-center case mix. As high disease prevalence increases the proportion of true malignant cases, it can mathematically lower the negative predictive value (NPV), meaning even a negative test result carries a relatively higher residual risk of malignancy in such se ttings . Feature-level trends were coherent: multilocular- ity, mixed/solid composition, and free fluid associated with malignancy, whereas unilocular and cystic morphology favored benign disease. Among single features, B2 (solid components <7 mm) and B3 (acoustic shadows) were strongly predictive of benignity, while M1 (irregular solid tumor) and M5 (very strong Doppler flow) dominated malignant findings. Our accuracy sits at the lower end of seminal IOTA validations (typically sen- sitivity/specificity ~90 - 96%) but remains clinically robust [12] [14] [15].The in- determinate proportion (8.5%) closely matches large external validations report- ing ~7 - 11% [12] [14] [15]. Consistent with IOTA descriptors, acoustic shadows (B3) were benign-leaning— commonly seen in fibromas or dermoids— while asci- tes and solid/multilocular -solid architecture tracked with malignancy [12 ] [15] [21]. Head-to-head and synthesis studies from Asia report comparable or slightly higher performance for SRs and related models. Indian and regional cohorts have shown mid -80s to mid -90s sensitivities/specificities for SRs and ADNEX, even with non-expert examiners [16] [21] [22]. In particular, Khastgir et al. found SRs and ADNEX to outperform RMI 4 overall; O-RADS tended to maximize sensitiv- ity but sometimes at the expense of specificity— an effect echoed in systematic comparisons [16] [21] [23]. Against this backdrop, our point estimates are plau- sible for a high- prevalence oncology setting and align with the directionality of feature-outcome associations reported elsewhere [12] [14]-[16] [21] [23] [24]. Several context factors likely explain the modestly lower sensitivity/specificity than multicenter benchmarks: (i) case mix/prevalence — our malignancy rate of 43.6% can depress NPV and alter decision thresholds; (ii) operator variability — features such as papillary projections (M3), vascular flow scoring (M5), and the recognition of subtle solid components or septations are particularly prone to sub- jective interpretation, affecting SR accuracy; (iii) equipment and protocol hetero- geneity— different platforms and the need to alternate TVS/TAS in large or high- rising masses; and (iv) time to surgery (≤120 days) — interval change in lesion characteristics can introduce verification drift. These factors are typical in LMIC oncology pathways and likely account for part of the gap from idealized multicen- F. Khatoon et al. DOI: 10.4236/ojog.2025.1512179 2134 Open Journal of Obstetrics and Gynecology ter conditions [12] [14] [15] [22]. Indeterminate SR classifications were uncommon (8/94) yet clinically im- portant. In our series, mixed patterns yielded mixed outcomes ( e.g., M2 + B2 oc- curred in three cases, two benign and one malignant ), whereas B3 + M4 + M5 skewed malignant and B3+M4 skewed benign. This reinforces standard escala- tion: apply SRs first; if indeterminate, proceed to a secondary risk tool (e.g., AD- NEX) or expert review, as recommended in the IOTA three-step strategy to reduce indeterminacy while preserving specificity [14] [15] [22]. In resource-constrained settings, this tiered approach can foc us on oncologic referrals and limit unneces- sary laparotomies. Adnexal masses, particularly ovarian tumors, are a significant clinical challenge because of the difficulty in early diagnosis and the potential for malignancy, espe- cially in low -resource settings like Bangladesh. Many patients present with ad- vanced-stage disease, which is often associated with poorer prognosis and survival rates. For Bangladesh and similar contexts, SRs offer a low-cost, teachable frame- work with performance that compares favorably to biomarker-heavy indices. Our data echo prior Bangladeshi experience where SRs outperformed RMI 4 against histopathology [20]. Given the high malignancy prevalence in oncology centers, emphasizing structured SR acquisition, Doppler standardization, and brief up- skilling on feature recognition could lift sensitivity without sacrificing specificity. Embedding a protocolized fallback (ADNEX or expert adjudication) for indeter- minate scans would further streamline triage. Stratified analyses by menopausal status and histotype, plus decision -curve evaluation, would clarify where SRs add the most net clinical benefit and how to operationalize them across referral tiers. Considering future research, IOTA SR should be evaluated alongside other in- dicators like serum CA-125 and contrast-enhanced ultrasound to further improve the ability to differentiate benign from malignant masses. In addition, larger pro- spective multicenter studies with varied demographics would help validate IOTA SR across different clinical situations and its use in detecting early -stage malig- nancies. Finally, a review of borderline and uncommon malignancies would help refine the rules and enhance the specificity of the system. 5. Strengths and Limitations This study has several strengths. Its prospective design with histopathology as the gold standard ensured a reliable assessment of diagnostic accuracy. The compre- hensive evaluation of all IOTA Simple Rule features, including indeterminate cases, allowed de tailed feature -level analysis. Conducted in a tertiary oncology center, the study captured a clinically relevant spectrum of adnexal masses and provides contextually relevant evidence for Bangladesh and other LMIC settings, addressing a critical regional k nowledge gap. However, there are notable limita- tions. The single-center design and relatively small sample size may limit the gen- eralizability of findings. Operator dependence of ultrasound, despite adherence to F. Khatoon et al. DOI: 10.4236/ojog.2025.1512179 2135 Open Journal of Obstetrics and Gynecology IOTA protocols, could introduce variability in feature detection. Referral bias to- ward complex or high-risk cases may have led to an overrepresentation of malig- nant lesions, influencing sensitivity and specificity estimates. While the IOTA Simple Ultrasound Rules demonstrated robust diagnostic performance in our co- hort, the observed sensitivity (84.2%) and specificity (87.2%) were slightly lower than the ranges reported in large multicenter validations (92 - 96%). This differ- ence may reflect several factors, including the relatively small sample size, single - center design, and operator experience variability. Additionally, as a tertiary on- cology center, our cohort likely included a higher proportion of complex or ad- vanced masses, which could affect the performance metrics. These considerations should be considered when interpreting the results and underscore the need for larger, multicenter studies in Bangladesh to confirm generalizability. 6. Conclusion The IOTA Simple Ultrasound Rules demonstrated strong diagnostic performance in differentiating benign and malignant adnexal masses in a tertiary oncology set- ting in Bangladesh, with high sensitivity, specificity, and overall accuracy. Feature- level analysi s confirmed that key sonographic markers such as multilocularity, solid components, and ascites effectively discriminate malignancy, while indeter- minate cases highlight the need for careful evaluation. These findings support the feasibility and clinical utility of implementing IOTA protocols in LMIC contexts, potentially improving early detection, guiding appropriate referrals, and reducing unnecessary surgical interventions. However, further large -scale, multicenter studies are warranted to validate these results and ensure broader applicability across diverse healthcare settings. Author Contributions All authors contributed to the development of this work. Conflicts of Interest The authors declare no conflicts of interest regarding the publication of this paper.

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