Results
During the two-year study period, 1442 consecutive women with suspected early pregnancy complications attended the Early Pregnancy Assessment Unit for a total 1711 ultrasound scans that were all carried out by a single clinician. When women presented for more than one pregnancy during the study period, only findings from the first pregnancy were included in the data collection. Of the 1442 women, 101 (7.0%, 95% CI 5.7 – 8.3) were excluded from the data analysis as they did not undergo a transvaginal ultrasound scan. The median age of the 1341 women included in the final data analysis was 33 years (range 16 – 51), the median parity was 0 (range 0 - 9) and the median BMI was 23.3 (range 15.8 – 56.2). 1233/1341 (91.9%, 95% CI 90.5 – 93.4) women conceived spontaneously and the remaining 108 women conceived after fertility treatment. There were 72 women with a previous diagnosis of endometriosis, 44 of whom had undergone surgical excision of the disease. The indications for attendance at the Early Pregnancy Clinic are provided in the supplementary material (Table S1).
Evidence of ovarian endometriomas and/or deep endometriosis was found in a total of 66/1341 (4.9%, 95% CI 3.8 – 6.2) women. Demographic characteristics of women with and without ultrasound evidence of endometriosis are shown in Table 1. We found ovarian endometriomas in 9/66 (13.6%, 95% CI 5.3 – 21.9) women, 33/66 (50.0%, 95% CI 37.9 - 62.1) had deep endometriosis and 24/66 (36.4%, 95% CI 24.8 – 48.0) had evidence of both ovarian and deep endometriosis. In women with ovarian endometrioma, 26 cysts were identified in the right ovary and 22 in the left ovary. In the 57 women with endometriotic nodules, the most common site was the rectovaginal space (n = 50) and in the region of the uterosacral ligaments (n = 37). The median number of nodules was 2 (range 0 - 7). Bowel involvement was diagnosed in 17/57 (29.8%, 95% CI 17.9 – 41.7) women with deep endometriosis and 2/57 (3.5%, 95% CI 0 – 8.3) had evidence of bladder/vesicouterine involvement.
For 33/66 (50%, 95% CI 37.9 – 62.1) women with evidence of endometriosis, this was a new diagnosis made for the first time during their early pregnancy scan. The remaining 33 women were aware of the diagnosis prior to their pregnancy. A further 39/1341 (2.9%, 95% CI 2.0 – 3.8) women reported a previous diagnosis of endometriosis, of which 32/39 (82.1, 95% CI 70.1 – 94.1) had undergone surgical treatment. However, none of these 39 women had evidence of active endometriotic lesions on ultrasound at the time of their attendance to the early pregnancy unit.
The proportion of women with endometriosis who conceived after fertility treatment (21.2%, 95% CI 12.1-33.0) was much higher compared to women without endometriosis (7.5%, 95% CI 6.1-9.0). A total 8/33 (24.2%, 95% CI 9.6 – 38.8) of women with known endometriosis conceived following fertility treatment which was similar to 6/33 (18.2%, 95% CI 5.0 – 31.4) women with a new diagnosis (p = 0.5540).
The list of all gynaecological diagnoses following pelvic ultrasound examination are documented in Table 2. In 33/66 (50%, 95% CI 37.4 – 62.6) women with evidence of endometriosis, endometriosis was an isolated abnormality. In the remaining 33 women, concomitant abnormalities were also noted on pelvic ultrasound examination (Table 3).
The results of a univariate analysis suggested that the presence of endometriosis was significantly associated with infertility, low parity, congenital uterine anomalies, fibroids and adenomyosis. The largest effect was for congenital uterine anomalies, where the odds of concurrent endometriosis was five times higher than in women without. There was also some difference between ethnicities. The results of the univariate analysis are included in the supplementary material (Table S2). The results of a multivariate analysis examining these associations is shown in Table 4. The analysis suggested that ethnicity, infertility, congenital uterine anomalies and fibroids were associated with the presence of endometriosis. After adjusting for these variables, there was no further evidence that either parity or adenomyosis were associated with the presence of endometriosis. East Asian women had the highest chance of endometriosis, with odds over 50% higher than for Caucasian women. Women that conceived following fertility treatment had a higher endometriosis risk, with the odds being over three times higher than those who did not undergo fertility treatment. The presence of congenital uterine anomalies remained strongly associated with the presence of endometriosis.