Diagnostic accuracy of transvaginal ultrasound examination for assigning a specific diagnosis to adnexal masses: A meta-analysis

Abstract

Transvaginal ultrasound (TVUS) is a standard imaging modality for differentiating patients with benign or malignant suspected adnexal mass. To date, numerous studies have assessed the diagnostic accuracy of TVUS in various settings but with variable results. Therefore, the purpose of the present study was to perform a meta-analysis to evaluate the diagnostic accuracy of TVUS for the differentiation of adnexal masses. An electronic search in the Medline, Scopus, Cochrane and Embase databases from inception till November 2019 was carried out. Meta-analysis was performed to obtain pooled sensitivity and specificity of TVUS to distinguish malignant from benign adnexal masses. The quality assessment of diagnostic accuracy studies-2 tool was used to assess the quality of trials. A total of 41 studies with 18,391 patients were included. The pooled sensitivity and specificity of TVUS was 92% (95% CI: 90-94%) and 89% (95% CI: 85-92%), respectively. The area under the receiver operating characteristic curve was 0.96 (95% CI: 0.84-1.00). There was considerable heterogeneity with a statistically significant chi-square test (P<0.001) and I² of 99%. Meta-regression results indicated that index test standards, patient selection bias and study design were potential sources of heterogeneity (P<0.05). The funnel plot was symmetrical and low publication bias was confirmed by an insignificant Deek's test (P=0.90). The present systematic review and meta-analysis indicated that TVUS is useful in differentiating between benign and malignant tumours among patients with suspected adnexal mass with high sensitivity and specificity.

Keywords: adnexal tumour; meta-analysis; transvaginal ultrasonography; validation studies.

Figure 1

Search strategy of the review.

Figure 2

Quality assessment using the quality assessment of diagnostic accuracy studies-2 tool indicating the percentage risk of bias for each characteristic.

Figure 3

Forest plot indicating the pooled sensitivity and specificity for transvaginal ultrasound. A point estimate and 95% CI of each individual study is presented by a square and horizontal lines, respectively. Diamonds indicate combined sensitivity and specificity with the red line indicating the combined point estimate.

Figure 4

Likelihood ratio scatter diagram providing a summary matrix of the positive and negative likelihood ratio of TVUS for diagnosing adnexal masses. The scatter diagram suggested that TVUS is useful only for confirming the diagnosis of adnexal masses (when positive). LRN, likelihood ratio negative; LRP, likelihood ratio positive; LLQ, left lower quadrant; LUQ, left upper quadrant; RLQ, right lower quadrant; RUQ, right upper quadrant; TVUS, transvaginal ultrasound.

Figure 5

SROC with pooled estimates of SENS and SPEC and AUC for transvaginal ultrasound in the diagnosis of adnexal masses. An AUC value closer to 1 is indicative of a better diagnostic value. SROC, summary receiver operator characteristic curve; AUC, area under the curve; SENS, sensitivity; SPEC, specificity.

Figure 6

Fagan nomogram for calculating post-test probabilities of the disease from the LR of the test result. The straight line drawn from the patient's pre-test probability of the disease through the LR of the test result points to the post-test probability of the disease. LR, likelihood ratio; Prob, probability; Pos, positive; Neg, negative.

Figure 7

Bivariate boxplot of the sensitivity and specificity in the included studies. The inner oval region represents the median distribution of the data points and the outer oval represents the 95% confidence boundary. Studies outside this grey area are considered as outliers. LOGIT_SENS, logit sensitivity; LOGIT_SPEC, logit specificity.

Figure 8

Meta-regression plot for different variables to explore sources of heterogeneity in the meta-analysis. Point estimates are depicted by red circles and 95% Cis are depicted by horizontal lines for each variable. Statistically significant results are marked by asterisks. ^*P<0.05; ^**P<0.01.

Figure 9

Deek's funnel plot for assessing publication bias in the included studies with super-imposed regression line. The statistically insignificant P-value (0.90) for the slope coefficient suggests symmetry in the data and a low likelihood of publication bias. ESS, effective sample size.