Interpretation
In this population, approximately half of women with endometriosis were asymptomatic of endometriosis and were diagnosed for the first time in pregnancy. This is in agreement with previous studies which showed that endometriosis is a relatively common finding in asymptomatic, fertile women.22 In our study population, women with endometriosis were more likely to have conceived using assisted reproductive techniques. The proportion of women with a new diagnosis of endometriosis that conceived following fertility treatment was similar to that of women with known endometriosis. These findings support the theory that women with difficulty conceiving or undergoing fertility treatment are likely to have a higher prevalence of pelvic endometriosis.4,23 In our study, the proportion of pregnancies conceived following fertility treatment was high, which is likely to reflect the high number of IVF treatment cycles performed in the local central urban area.
Our study demonstrated that only 14% of women with ultrasound features of endometriosis had evidence of endometrioma in the absence of deep nodules. These findings support those of Exacoustos et al (2018) that reported ovarian endometriomas as rarely isolated lesions, but commonly associated with pouch of Douglas obliteration, pelvic adhesions and the presence of endometriotic nodules.24 Our study showed that 15% of women of East Asian origin had evidence of pelvic endometriosis. This supports previous findings that moderate-to-severe endometriosis is more common in women with East or South East Asian ethnicity attending a tertiary referral centre.25
The relationship between adenomyosis and endometriosis has previously been described in the literature. Naftalin et al (2012) found that women with a previous or current diagnosis of endometriosis were significantly more likely to have adenomyosis, with an odds ratio of 4.06 (95% CI: 2.25–7.33).13 Di Donato et al (2014) demonstrated a 21.8% prevalence of adenomyosis in women affected by endometriosis.26 In our study of pregnant women with endometriosis we did not find as strong an association with adenomyosis as previously reported. However, women in our study population were much younger (median age 33 vs 40 in the study by Naftalin et al.)13 which could explain our finding of much lower prevalence of adenomyosis in women with and without endometriosis.