IOTA Simple Rules Risk calculator

Clinical inputs

• Ultrasound center
• B1 unilocular cyst
• B2 solid parts smaller than 7 mm
• B3 acoustic shadows
• B4 smooth multilocular tumor smaller than 100 mm
• B5 no blood flow, color score 1
• M1 irregular solid tumor
• M2 ascites
• M3 at least 4 papillary structures
• M4 irregular multilocular-solid tumor at least 100 mm
• M5 very strong flow, color score 4

Primary source

Timmerman D et al. Predicting the risk of malignancy in adnexal masses based on the Simple Rules from the International Ovarian Tumor Analysis group. Am J Obstet Gynecol. DOI: 10.1016/j.ajog.2016.01.007. PMID: 26800772. Table 8 of the author manuscript, updated on all 4848 patients: intercept −0.97; B1 −3.41; B2 −2.25; B3 −1.66; B4 −2.75; B5 −1.86; M1 2.19; M2 2.65; M3 1.53; M4 0.98; M5 1.55; oncology center 0.92. Risk = exp(RS) / (1 + exp(RS)), where RS adds the intercept to each feature that is present. The manuscript's worked example is an oncology-center mass with B3, M2, and M5: RS = −0.97 − 1.66 + 2.65 + 1.55 + 0.92 = 2.49, and the risk is 92.3%. The validation text evaluates a 1% risk cutoff and a 30% risk cutoff, and says a risk of 30% or higher is the high-risk group. (2016)