Impaired inflammatory state of the endometrium: a multifaceted approach to endometrial inflammation. Current insights and future directions

Abstract

New insights into the complex and fine-regulated inflammatory mechanisms involved in the endometrium reveal multiple facets to the problem of endometrial inflammation. However, the entity termed chronic endometritis is to date restricted to infectious etiology and managed with antibiotics. Conversely, the concept of impaired inflammatory state of the endometrium (IISE) provides a more global approach to defective endometrial inflammation, considering both infectious and non-infectious etiology. A non-systematic review was done through a search on MEDLINE, EMBASE, Global Health, The Cochrane Library, Health Technology Assessment Database and Web of Science, research registers. Pertinent original and review articles, published in English or French until December 31, 2019, were selected. A compelling body of evidence demonstrates transient, repeated and persistent IISE to be a major factor of most problematic disorders in obstetrics/gynecology, such as endometrial polyps, unexplained infertility, miscarriage, placenta-related pathology and endometrial cancer. When scheduled accordingly, hysteroscopy can play a key role in the IISE assessment. Robust data suggests the pertinence of minimal-effective anti-inflammatory regimens for therapeutic IISE targeting. This review provides a comprehensive update on the multiple facets of inflammation in the endometrial physiology and pathology. Further research is needed to improve classification, diagnosis and treatment of IISE.

Keywords: chronic endometritis; endometrial polyp; impaired inflammatory state of the endometrium; infertility.

Fig. 1

Schematic illustration of acute inflammation orchestrated by the innate and adaptive immune system

Fig. 2

Causes, mechanisms and features of chronic inflammation

Fig. 3

Time-dependent fluctuations of the main endometrial leukocyte populations throughout the menstrual cycle and early pregnancy

Fig. 4

Hysteroscopic signs of what is termed chronic endometritis. A) micropolyps; B) hyperemia: red spots and petechiae; C) spontaneous bleeding and stromal edema; D) “chronic endometritis-like” redness and edema at day 14 of the menstrual cycle: progestin-only contraception