A prospective study of the role of ultrasound in the management of adnexal masses in pregnancy.

Objective: To assess the clinical relevance of adnexal masses in pregnancy and the usefulness of ultrasound in their management.

Design: A prospective study on pregnancy complicated by adnexal masses.

Setting: Department of Obstetrics and Gynaecology in Italy.

Population: 6636 women with pregnancy in utero followed in our clinic from January 1996 to December 1999.

Methods: From 1996 to 1999, all ovarian cysts with a diameter exceeding 3 cm were prospectively recorded and followed. The management was expectant except in case of symptoms or suspected malignant features. Cysts suggestive of borderline tumours were treated expectantly.

Main Outcome Measures: Clinical relevance of adnexal masses in pregnancy, the outcome of these pregnancies and the usefulness of ultrasound examination in their management.

Results: We detected 82 cysts in 79 of 6636 women (1.2 in 100 term pregnancies). Sixty-eight women were asymptomatic at the time of diagnosis, whereas 11 (13.9%) were diagnosed because of pain. Diagnosis occurred in the first trimester for 57 cases and in the second or third trimester in 22 (27.8%). One-half of the cysts were simple and anechoic at ultrasound. Fifty-seven had a diameter not exceeding 5 cm. Forty-two cyst resolved in pregnancy without treatment. Three cysts required surgery within few days (torsion). One woman required laparotomy at the 37th week of gestation, due to torsion. When one case of termination was excluded, 78 women delivered at term (66 vaginally, 12 by caesarean section). Nineteen women underwent surgery after pregnancy. We recorded three Stage Ia borderline tumours, accounting for 3/82 cysts (3.6%) and 3/30 persisting masses (10%).

Conclusion: Ultrasound allows definition of ovarian cysts in pregnancy and this positively impacts on management. The incidence of cancer among persistent masses is lower than previously reported. Acute complications in stable cysts are extremely uncommon after the first trimester. An expectant management is successful in the majority of cases and should be considered more often. Routine removal of persistent cysts is not justified.