Diagnosing Polyps on Transvaginal Sonography: Is Sonohysterography Always Necessary?

Endometrial polyps are localized overgrowth of glands, stroma, and blood vessels and reported in 13% to 50% of women with dysfunctional uterine bleeding. Transvaginal ultrasound (TVUS) is the initial noninvasive modality of choice for the evaluation of endometrial polyps. The addition of intrauterine contrast by adding saline during saline infusion sonohysterography (SIS) has been reported to improve diagnostic accuracy in detecting of endometrial polyps. Given all the technical advances in ultrasound instrumentation and technology over the last 10 years, we wanted to revisit the diagnostic accuracy and associated confidence level of TVUS and SIS for detecting endometrial polyps.

The aims of this study was to determine the diagnostic accuracy of TVUS in detecting endometrial polyps in patients with abnormal uterine bleeding or infertility and to determine if SIS is necessary when the level of confidence that a polyp is present is high.

A total of 144 patients who underwent both TVUS and SIS for the evaluation of abnormal uterine bleeding and infertility were retrospectively identified and independently reviewed by 2 blinded readers. Examinations were graded as polyps absent, equivocal for polyps, and polyps definitely present. Interreader agreement for TVUS grade was assessed using Cohen kappa. Hysteroscopy and histopathology were used as the reference standard for the final diagnosis. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value were calculated, and confidence intervals (CIs) were computed.

From the combined assessments of both readers (288 reads), 24.7% were definitively positive for polyps, 47.2% were negative, and 28.1% were equivocal by TVUS. Interreader agreement was good with a kappa of 0.66 (95% CI, 0.56-0.76). Among the 108 reads where hysteroscopy/histopathology results were available, even when diagnostic confidence for the presence of polyps was high, TVUS had a PPV of 65.2% (95% CI, 42.1%-88.9%). This PPV was significantly lower than the corresponding PPV of SIS of 88.5% (95% CI, 77.4-100.0%; P = 0.021 for the difference).

Saline infusion sonohysterography has better diagnostic accuracy for the detection and exclusion of endometrial polyps than TVUS, even in cases where the diagnostic confidence for the presence of polyps is high. Saline infusion sonohysterography may still be needed to confirm a TVUS diagnosis for polyps to limit the number of negative hysteroscopies.