P-757 The classification and management of adnexal masses identified during pregnancy
Authors: Barcroft J , Pandrich M , Landolfo C , Del Forno S , Parker N , Cooper N , Pikovsky M , Murugesu S , Novak A , Kyriacou C , Al Memar M , Yazbek J , Timmerman D , Saso S , Bourne T 
Published: June 2023

Abstract

Study question
How do we classify adnexal masses (ovarian cysts) identified during pregnancy and how should we manage them?

Summary answer
Adnexal masses (ovarian cysts) should be managed expectantly in pregnancy, given the low rate of complications and low prevalence of malignancy.

What is known already
Conservative management of adnexal masses (ovarian cysts) is preferable during pregnancy, due to the maternal and fetal risks associated with surgery. Accurate diagnosis is key to safe expectant management. Various ultrasound-based models exist to classify adnexal masses; however, none have been validated for use in pregnancy. Adnexal mass morphology can change during pregnancy due to decidualisation, which is often difficult to distinguish from underlying neoplastic processes. We aim to evaluate:(1) the performance of current methods of adnexal mass classification in pregnancy, (2) understand the natural course of adnexal masses in pregnancy, particularly the presence of decidualisation and incidence of complications.

Study design, size, duration
Retrospective analysis of prospectively collected data between January 2017- November 2022. To classify adnexal masses (ovarian cysts), we evaluated: Expert subjective assessment (SA), IOTA Simple Rules (SR) and the IOTA Assessment of Different Neoplasias of the Adnexa (ADNEX) model. The end point was either the histological examination of tissue removed at surgery or the subjective classification of adnexal masses at the postnatal scan in women managed conservatively.

Participants/materials, setting, methods
Women with an adnexal mass identified on gynaecological ultrasound in pregnancy at a tertiary London University Hospital were included. Relevant clinical data was extracted, including age, gestation and cyst-related complications. Adnexal masses were classified at the first antenatal and postnatal ultrasound examination according to SA, SR and the ADNEX model (10% risk of malignancy cut off) and correlated to histology for adnexal masses managed surgically. IOTA simple descriptors were used to classify benign adnexal masses.

Main results and the role of chance
254 women (median age 33-years old, range:18-49) with an adnexal mass/cyst were included at a median gestation of 12 weeks, (range:4-36). 13 (5.1%) conceived through assisted reproductive techniques. Spontaneous resolution occurred in 24.5% of cases, and 21 were lost to follow up (8.3%). According to Simple Descriptors, 38.6% were simple, 22.0% were endometriomas and 19.7% were dermoid cysts.
Antenatally, SA outperformed ADNEX, based on specificity (94.6 vs.92.2%) and sensitivity (60 vs.55.6%) respectively. SA and ADNEX had a negative predictive value(NPV) of 96.1% and 98.3% respectively. Postnatally, SA had a higher sensitivity than ADNEX (75 vs.50%), but a lower specificity (94.1 vs.96.9%). SA and ADNEX had a NPV of 94.1% and 97.5% respectively.
Three (1.3%) underwent acute surgery during pregnancy: one ovarian torsion (9/40), and two cyst ruptures (11/40, 30/40). Presumed decidualisation occurred in 29.5% of endometriomas. Three (1.3%) underwent cyst removal during caesarean section, two for suspicion of BOTs (one had suspected decidualisation) and one for patient preference. On histology, the suspected decidualised mass was a serous BOT, and the suspected BOT was a struma ovarii.
In the postnatal period (12 weeks), four underwent surgery for suspicion of BOTs, two were confirmed BOTs and two were benign cystadenomas on histology.

Limitations, reasons for caution
The dataset as expected contains a relatively small number of malignancies (prevalence 3.9%) and so any analysis of test performance to discriminate between benign and malignant disease must be interpreted with caution. A larger prospective multicentre study is needed to do this.

Wider implications of the findings
Our data suggest that a number of cysts in pregnancy will resolve, a few will be associated with acute complications and the risk of malignancy is very low. Accordingly, the study supports an expectant management approach for adnexal masses (ovarian cysts) detected in pregnancy.

Trial registration number
Not applicable