Uterus
Nontumor
Endometritis
Author: Stephanie L. Skala, M.D.
Editorial Board Member: Gulisa Turashvili, M.D., Ph.D.
Deputy Editor-in-Chief: Jennifer A. Bennett, M.D.
Last author update: 3 August 2021
Last staff update: 19 April 2023
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed search: Endometritis[TI] uterus[TIAB] pathology
Table of Contents
Definition / general | Essential features | ICD coding | Epidemiology | Sites | Pathophysiology | Etiology | Clinical features | Diagnosis | Prognostic factors | Case reports | Treatment | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review style answer #1 | Board review style question #2 | Board review style answer #2Cite this page: Skala SL. Endometritis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/uterusendometritis.html. Accessed April 23rd, 2024.
Definition / general
- Inflammatory process involving the endometrium
Essential features
- Endometrial stromal plasma cells required for the diagnosis of chronic endometritis
- Chronic endometritis is implicated in infertility and recurrent pregnancy loss
- Acute endometritis typically represents ascending infection from lower genital tract
- Xanthogranulomatous endometritis usually associated with cervical stenosis
ICD coding
Epidemiology
- Typically premenopausal women
Sites
- Endometrium
Pathophysiology
- Unknown
Etiology
- Chronic endometritis
- Unclear etiology
- Causative organisms include Streptococcus species, Escherichia coli, Enterococcus, Staphylococcus species and Mycoplasma / Ureaplasma species (Fertil Steril 2008;89:677)
- Acute endometritis
- Ascending infection from lower genital tract
- Causative organisms include Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, Mycoplasma species (Sex Transm Infect 2020;96:436)
- Group A streptococcal infection rarely causes postpartum endometritis (Postgrad Med 2020;132:526)
- May be secondary to retained products of conception
- Actinomyces-like organisms are a rare cause of acute and chronic endometritis with prolonged intrauterine device use (Int J Gynecol Pathol 2019;38:138)
- Ascending infection from lower genital tract
- Xanthogranulomatous endometritis
- Pyometra, cervical stenosis (Clin Case Rep 2021;9:e04299, J Midlife Health 2019;10:206)
- Granulomatous endometritis
- Tuberculosis (Am J Obstet Gynecol 2020;223:737.e1)
- Sarcoidosis (Int J Surg Pathol 2017;25:246)
- Coccidioidomycosis (Arch Pathol Lab Med 1986;110:232)
- Postendometrial ablation (Br J Obstet Gynaecol 1992;99:928)
- Cytomegalovirus (Am J Surg Pathol 1992;16:716)
Clinical features
- Chronic endometritis
- Often asymptomatic (Int J Gynecol Pathol 2010;29:44, Am J Reprod Immunol 2011;66:410)
- Abnormal uterine bleeding, pelvic discomfort (Int J Gynecol Pathol 2010;29:44, Am J Reprod Immunol 2011;66:410)
- Associated with moderate to severe intrauterine adhesions (Fertil Steril 2019;111:1002)
- May be associated with unexplained infertility, unexplained recurrent miscarriages and repeated implantation failure after in vitro fertilization embryo transfer (Mod Pathol 2010;23:1136, Fertil Steril 2011;95:1156, Fertil Steril 2010;93:437)
- Somewhat controversial
- Acute endometritis
- Fever, pelvic pain, vaginal discharge
Diagnosis
- Microscopic examination is the gold standard
- Hysteroscopic scoring systems have been proposed (J Minim Invasive Gynecol 2020;27:1127)
- Features: endometrial hyperemia (focal or diffuse), hemorrhagic spots, dilated endometrial vessels, micropolyps, endometrial polyp
Prognostic factors
- Women with cured chronic endometritis may have higher ongoing pregnancy rate / live birth rate, clinical pregnancy rate and implantation rate (Fertil Steril 2018;110:103)
- Untreated acute endometritis has a fatality rate ~17% (StatPearls: Endometritis [Accessed 3 August 2021])
- Acute endometritis is not associated with infertility (Am J Obstet Gynecol 2003;188:141)
Case reports
- 61 year old woman with pyometra and enlarged uterus (J Midlife Health 2019;10:206)
- 70 year old woman with intrauterine device in place for 42 years (Acta Medica (Hradec Kralove) 2019;62:35)
- 74 year old woman with endometrial fluid collection and clinical concern for endometrial cancer (Radiol Case Rep 2018;14:121)
Treatment
- Chronic endometritis
- Antibiotic therapy (often empiric treatment with doxycycline [first line] or metronidazole / ciprofloxacin [second line]) (Am J Reprod Immunol 2017;78:e12719)
- Acute endometritis
- Oral antibiotics for mild disease (doxycycline / metronidazole, levofloxacin / metronidazole or amoxicillin / clavulanate) (StatPearls: Endometritis [Accessed 3 August 2021])
- IV antiobiotics (such as gentamicin or clindamycin) if more severe (StatPearls: Endometritis [Accessed 3 August 2021])
Microscopic (histologic) description
- Chronic endometritis
- Plasma cells (required) with or without lymphoid follicles
- Presence of eosinophils associated with plasma cells (Hum Pathol 2010;41:33)
- Currently no specific guidelines about required number of plasma cells or whether detection of rare plasma cells by IHC alone is sufficient (Int J Gynecol Pathol 2020 Dec 14 [Epub ahead of print])
- Plasma cells can be seen in disordered proliferative or breakdown endometrium in the absence of infection (Hum Pathol 2007;38:581)
- Spindled stromal cells
- Endometrial dating is unreliable due to frequent out of phase morphology (Am J Reprod Immunol 2011;66:410)
- Higher prevalence in proliferative phase (Reprod Biomed Online 2018;36:78)
- Note: structural abnormalities (endometrial polyp, submucosal leiomyoma) can be associated with plasma cells; such cases should not be diagnosed as chronic endometritis
- Plasma cells (required) with or without lymphoid follicles
- Acute endometritis
- Neutrophils infiltrating and destroying endometrial epithelium
- Neutrophils filling gland lumina
- With or without microabscess formation
- Granulomatous endometritis
- Clusters of epithelioid histiocytes rimmed by lymphocytes
- Cytopathic effects if viral etiology (herpes simplex virus, cytomegalovirus)
- Tuberculosis: necrotizing granulomas with multinucleated giant cells, usually in superficial functional endometrium (Am J Obstet Gynecol 2020;223:737.e1)
- Sarcoidosis: nonnecrotizing granulomatous inflammation, more commonly in myometrium
- Xanthogranulomatous endometritis
- Abundant foamy histiocytes, siderophages, neutrophils, plasma cells, lymphocytes
- With or without fibrosis, calcification
Microscopic (histologic) images
Contributed by Stephanie L. Skala, M.D. and Yuri Tachibana, M.D.
Chronic endometritis
Spindled endometrial stroma
Endometrial stromal plasma cells
Eosinophils and plasma cells
Plasma cells
CD138
MUM1 highlights plasma cells
Xanthogranulomatous endometritis
Foamy histiocytes and eosinophils
Lymphoid follicles and histiocytes
Acute endometritis
Prominent intraluminal neutrophils
Positive stains
- Chronic endometritis
- CD138 / syndecan in plasma cells (Arch Pathol Lab Med 2004;128:1000)
- MUM1 in plasma cells; higher sensitivity, cleaner background (Int J Surg Pathol 2019;27:372)
Sample pathology report
- Endometrium, biopsy:
- Chronic endometritis
Differential diagnosis
- Predecidualized endometrial stromal cells:
- Lack "clock face" chromatin
- Plasma cell markers negative
- Lymphoma:
- Atypical proliferation of clonal lymphoid cells
Board review style question #1
What clinical scenario is most likely associated with the endometrial biopsy findings shown above?
- Cervical stenosis
- Chlamydia
- Tuberculosis
- Use of intrauterine device
Board review style answer #1
Board review style question #2
Which of the following conditions is thought to be associated with infertility and recurrent pregnancy loss?
- Acute endometritis
- Chronic endometritis
- Granulomatous endometritis
- Xanthogranulomatous endometritis
Board review style answer #2
