Introduction
Endometriosis is an oestrogen-dependent chronic inflammatory condition, characterised by the presence of endometrial-like tissue outside of the uterus.1 Three subtypes of endometriosis are described: superficial peritoneal, ovarian (endometrioma), and deep (infiltrating).2 The true prevalence of endometriosis is unknown. It is estimated to affect between 6–10% of women of reproductive age3 and is present in 50% of women with infertility who have evidence of normal ovulation and normospermic partners.4 In 50-60% of women, endometriosis is associated with debilitating pelvic pain which can have an adverse effect on quality of life.5 However, a proportion of women are relatively asymptomatic and less likely to attend for diagnostic tests or seek treatment.
The gold standard for diagnosis of endometriosis is histological examination of lesions excised during surgery.6However, when surgery is used to detect endometriosis, long delays of up to 7-8 years after onset of symptoms have been reported.7 There are no accurate non-invasive biomarkers for endometriosis and ultrasound or MRI are the only diagnostic tests which could be used as alternatives to surgery. Following recent advancements in technology and training, ultrasound is widely acknowledged as the first line investigation of choice in women with suspected endometriosis.8,9 A standardised approach for ultrasound assessment is well described in a recent consensus statement.10 Transvaginal ultrasound has been shown to have good concordance with laparoscopy for the diagnosis of deep endometriosis (kappa 0.76) and is highly reproducible for the detection of endometriotic cysts and nodules.11,12However, ultrasound is not a sensitive tool for the diagnosis of superficial endometriosis.11
Naftalin et al. found evidence of ovarian and/or deep endometriosis on transvaginal ultrasound examination in 6.4% of women attending a general gynaecology clinic.13 There have been no studies on the prevalence of ovarian endometriomas and deep endometriosis in pregnancy and there is no consensus regarding specialist care for women with endometriosis in pregnancy. Recent literature suggests that women with endometriosis have a higher risk of spontaneous miscarriage, preterm birth, small for gestational age babies, placenta praevia, antepartum haemorrhage, postpartum haemorrhage and preterm birth.14,15 Exacoustos et al reported that women with deep endometriosis have increased rates of Caesarean sections and surgical complications.16 Imaging offers the potential to diagnose endometriosis in early pregnancy and identify women at higher risk of adverse pregnancy outcomes.
The aim of this study was to assess the prevalence of ovarian endometriomas and deep endometriosis in women attending a dedicated early pregnancy assessment unit.