ENDOMETRITE: let's clarify

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The term endometritis refers to an inflammatory process affecting the endometrium. Two forms of endometritis can be distinguished, an acute and a chronic form. L'acute endometritis is generally preceded by pelvic inflammatory disease (PID) or an invasive gynaecological procedure and is manifested by the following symptoms: pelvic pain, vaginal discharge, dysfunctional uterine bleeding, changes in inflammatory indices, and hyperpyrexia. L'chronic endometritis is a chronic inflammatory disease characterised by the abnormal presence of plasma cells and natural killer cells in the endometrial stroma and is associated with reproductive failure. Aetiological factors of chronic endometritis include:

• Pathogens. Among the most common: Escherichia coli, Enterococcus faecalis, Streptococcus agalactiae (in 77.5% of cases), Mycoplasma/Ureaplasma (25%) and Chlamydia (13%)
• l'use of intrauterine devices 
• local radiotherapy treatments that reduce immune defences

In the literature, the prevalence of chronic endometritis is often underestimated because it is difficult to diagnose and varies between 15 and 50%. Most women with chronic endometritis are asymptomatic or present with non-specific symptoms such as pelvic pain, dysfunctional uterine bleeding, dyspareunia, leucorrhoea. Endometrial biopsy, preferably performed during the secretory phase of the menstrual cycle, is the gold-standard diagnostic of chronic endometritis. The biopsy allows the presence of CD 138+ plasma cells and CD56+ natural killer cells in the endometrial stroma to be confirmed by immunohistochemistry.¹. Proper evolution of pregnancy is enabled by an adequate endometrial immunological environment. Aberrant activation of immune cells at the level of the endometrial stroma, in fact, may cause alteration of the receptivity of the endometrium with consequent abnormalities in embryo implantation and in the evolution of pregnancy.^2-3-4. Data from the literature suggest a prevalence of chronic endometritis ranging from 7% to 58% in women diagnosed with polyabortion³. Recent studies in the field of reproductive medicine have also shown that antibiotic and corticosteroid treatment in the case of a positive histological diagnosis of chronic endometritis has improved the outcome of IVF cycles, although pharmacological protocols are not yet unambiguous and standardised. ^3-4.

1. Michael P. Rimmer, Katherine Fishwick, Ian Henderson et al. Quantifying CD138+ cells in the endometrium to assess chronic endometritis in women at risk of recurrent pregnancy loss: A prospective cohort study and rapid review. J. Obstet. Gynaecol. Res. Vol. 47, No. 2: 689-697, February 2021
2. Update 2022 ESHRE Recurrent Pregnancy Loss Guideline Development Group
3. Cicinelli E, Matteo M, Tinelli R, et al. Prevalence of chronic endometritis in repeated unexplained implantation failure and the IVF success rate after antibiotic therapy. Hum Reprod. 2015 Feb;30(2):323-30.
4. Simone Giulini, Valentina Grisendi, Giovanna Sighinolfi, et al. Chronic endometritis in recurrent implantation failure: Use of prednisone and IVF outcome, Journal of Reproductive Immunology 2022