Conclusion
Our study has demonstrated the prevalence of ovarian and deep endometriosis on ultrasound scans in women attending for early pregnancy assessment. Half of the women with evidence of endometriosis were asymptomatic and the diagnosis was made for the first time during pregnancy. In view of our findings, we propose that ultrasound may be a useful tool for the detection of endometriosis and to identify pregnant women who may benefit from specialist antenatal care. Further work is needed to determine whether women with a new first trimester ultrasound diagnosis of deep endometriosis are also at increased risk of adverse pregnancy outcomes.