Diagnosis of paraovarian cysts using transvaginal sonography combined with CA 125 determination

Abstract

Paraovarian cysts arise from the broad ligament between the Fallopian tube and the ovary1 and they appear sonographically as thin-walled, smooth-margined, usually unilocular cysts. In the literature, there are few reports addressing specifically the sonographic evaluation of these cysts, and results are conflicting1-5. We wish to add to the literature on paraovarian cyst diagnosis by reporting our findings on the diagnostic accuracy of transvaginal sonography alone or in combination with serum cancer antigen (CA 125) determination. A total of 315 adnexal masses in 313 non-pregnant women were included in this prospective study. The mean ± SD age of the study population was 41 ± 15 (range, 15–80) years. Two hundred and thirty-six (75%) patients were premenopausal and 79 (25%) were postmenopausal. One or 2 days prior to surgery all women underwent a detailed transvaginal ultrasound examination by an experienced operator and, on the same day, CA 125 was determined. Using B-mode sonography a paraovarian cyst was diagnosed when a unilocular ovoid cyst with an anechoic content and with a thin wall and smooth margin was seen, clearly separate from a normal ovary4, 5. At surgery, all adnexa were examined carefully and all adnexal masses removed. Seventeen of 313 women were found to have paraovarian cysts (prevalence, 5.4%). In these 17 paraovarian cysts the mean ± SD diameter was 47 ± 11 mm. In eight paraovarian cysts suspected on transvaginal sonography (Figure 1), the diagnosis was confirmed by surgery. Of 307 sonographic diagnoses of absence of paraovarian cysts, 298 were confirmed by surgical evaluation. In the nine false-negative cases, the presence of paraovarian cysts was missed because the sonographic appearance resembled that of a simple ovarian cyst (Figure 2). Adhesions or symptomatic adnexal masses were present in 44% of the false-negative cases (three severe pelvic adhesions and one torsion). The diagnostic accuracy of the combined methods for paraovarian cysts is reported in Table 1. The kappa index of 0.63 suggests good agreement between transvaginal sonography and surgery. The association with serum CA 125 measurement did not increase significantly the diagnostic accuracy of B-mode transvaginal sonography. Transvaginal ultrasound image of a paraovarian cyst: sonography showed a thin, smooth inner wall with an anechoic content separated from the normal ipsilateral ovary (calipers). A false-negative case. The presence of a paraovarian cyst was missed because of the failure to identify the ipsilateral ovary. Our study suggests the important role in the diagnosis of paraovarian cysts of transvaginal ultrasound performed by an experienced sonographer, showing good specificity with a good kappa value, but relatively low sensitivity. The co-existing presence of pelvic adhesions in some false-negative cases partially explains this low sensitivity. These data are at odds with those of Kim et al.4, who report a higher sensitivity (71%), and are in partial agreement with the data of Barloon et al.1, who report a very low sensitivity (7%). The absence of false-positive cases in our series is in accordance with the findings of Valentin6 who, in a small series of 167 cases with six paraovarian cysts, found a comparable specificity but a higher sensitivity (83%). Our findings confirm the high positive predictive value of transvaginal sonography in the characterization of several kinds of adnexal mass7, 8. S. Guerriero*, S. Ajossa*, S. Piras*, M. Angiolucci*, O. Marisa*, G. B. Melis*, * Department of Obstetrics and Gynecology, University of Cagliari, Ospedale San Giovanni di Dio, Via Ospedale 46, 09124, Cagliari, Italy