Prevalence of extrauterine pelvic lesions on transvaginal ultrasound in asymptomatic 20-39-year-old women.
OBJECTIVES
To estimate the prevalence of extrauterine pelvic lesions on transvaginal ultrasound examination of gynecologically asymptomatic women of fertile age, and to compare this prevalence between women with spontaneous menstrual cycles, those using the combined oral contraceptive (COC) pill and those using a gestagen intrauterine contraceptive device (IUD).


METHODS
Six hundred and forty-four gynecologically asymptomatic 20-39-year-old Caucasian women with no current or previous gynecological problems, who were recruited from a Swedish population registry, were examined with transvaginal ultrasound on cycle day 4-8. Our definition of ovarian cyst was a unilocular cyst with anechoic cyst contents ≥ 35 mm in mean diameter, or any other type of intraovarian lesion. The prevalence of extrauterine pelvic lesions was compared between women not using hormonal contraception and those using COC or a gestagen IUD.


RESULTS
Ovarian lesions were found in 24 (3.7%) women. One woman had bilateral ovarian lesions. An ultrasound diagnosis of paraovarian cyst was made in 41 (6.4%) women, of peritoneal cyst in four (0.6%) women and of hydrosalpinx in one (0.2%) woman. All incidentally detected lesions had a mean diameter of ≤ 5 cm. One 17-mm intraovarian lesion was suspicious for malignancy, and histology confirmed a Sertoli-Leydig cell tumor. The ultrasound diagnoses in the remaining 23 women were endometrioma (n = 10 (1.6%)), dermoid cyst (n = 5 (0.8%)), cystadenofibroma (n = 1 (0.2%)), mature teratoma (n = 1 (0.2%)) and functional cyst, i.e. a cyst that resolved within 3-5 months (n = 6 (0.9%)). Four women with an ultrasound diagnosis of a benign lesion were operated on, and the ultrasound diagnoses of endometrioma (n = 2), dermoid cyst (n = 1) and mature teratoma (n = 1) were confirmed histologically. The prevalence of persisting ovarian lesions was highest in women with spontaneous menstrual cycles (4.4% vs 0.9% and 0% in women using COC and gestagen IUD, respectively; P = 0.025), but age was the only factor independently associated with persisting ovarian masses, the prevalence increasing with age.


CONCLUSIONS
Benign ovarian lesions are found in about 1 in 25 gynecologically asymptomatic women aged 20-39 years with no history of gynecological disease. To be able to offer optimal management of such masses, their natural history needs to be elucidated in a large prospective observational study.