PTGER4 and endometriosis: Multiple linear regression analyses incorporating age, parity, menstrual phase, uterine size, co‐occurrence of ovarian endometrioma, deep endometriosis, or uterine fibroids, and use of iron supplements confirmed that adenomyotic lesions from the patients with EXB displayed significantly higher fibrotic content but significantly lower immunostaining levels of HIF‐1α, COX‐2, EP2, and EP4 (all p‐values <0.0083; all R2's ≥ 0.36).