Most Common Cause of Chronic Endometritis
Chlamydia trachomatis is the most common sexually transmitted bacterial cause of chronic endometritis, though common polymicrobial bacteria including Enterococcus, Escherichia coli, Streptococcus, and Staphylococcus species collectively represent the predominant etiologic agents in most cases. 1, 2
Primary Etiologic Agents
The microbial etiology of chronic endometritis is predominantly polymicrobial rather than attributable to a single organism:
Sexually Transmitted Pathogens
- Chlamydia trachomatis is recovered from the cervix in 5-39% of women with pelvic inflammatory disease and shows serologic evidence in 20-40% of women with PID history, making it the leading sexually transmitted bacterial cause 3, 1
- Neisseria gonorrhoeae is isolated from the cervix in 27-80% of acute PID cases, though its role in chronic endometritis specifically is less well-defined 3, 2
- Between 10-40% of untreated chlamydial or gonococcal cervicitis cases progress to symptomatic upper genital tract infection 3, 2
Common Bacterial Pathogens
- Polymicrobial common bacteria are the most frequently detected organisms in chronic endometritis, including Escherichia coli, Enterococcus faecalis, Streptococcus, and Staphylococcus species 4, 5
- Anaerobic bacteria (Bacteroides, Peptostreptococcus, Peptococcus) and facultative bacteria (Gardnerella vaginalis, Haemophilus influenzae) are isolated from the upper genital tract in 25-50% of acute PID cases 3, 2
- Bacterial vaginosis serves as an antecedent condition, with BV-associated organisms contributing to polymicrobial chronic endometritis 3, 2
Other Microbial Agents
- Mycoplasma hominis and Ureaplasma urealyticum are detected in the genital tract, though their specific role in chronic endometritis remains uncertain 3, 4
- Mycobacterium tuberculosis represents a rare but important cause in endemic regions 6
Clinical Context and Diagnostic Considerations
The distinction between acute and chronic endometritis is critical: acute PID typically involves ascending sexually transmitted infections, while chronic endometritis often results from persistent low-grade polymicrobial infection 7, 8
Key Risk Factors for Bacterial Ascent
- Uterine instrumentation (particularly IUD insertion) mechanically introduces organisms into the upper tract 3, 9
- Hormonal changes during menstruation alter the cervical mucus barrier 3, 9
- Cervical stenosis can lead to isolated endometritis 3
- Retained placental tissue, endometrial polyps, or intrauterine lesions predispose to chronic infection 6
Diagnostic Approach
- Histopathological detection of plasma cells in the endometrial stroma is the gold standard for diagnosis, with CD138 immunohistochemistry improving detection sensitivity 7, 5, 6
- Microbial culture identifies culturable organisms but misses fastidious or nonculturable bacteria 5
- Molecular PCR methods detect both culturable and nonculturable pathogens (Chlamydia, Enterococcus, E. coli, Gardnerella, Klebsiella, Mycoplasma, Neisseria, Staphylococcus, Streptococcus) with 75% sensitivity and 100% specificity when compared to combined classical diagnostic methods 5
Clinical Implications
Chronic endometritis is found in 2.8-56.8% of infertile women, 14-67.5% of women with recurrent implantation failure, and 9.3-67.6% of women with recurrent pregnancy loss 7
Treatment Efficacy
- Oral antibiotic therapy targeting the identified organisms is the most effective treatment 7, 4
- Patients with cured chronic endometritis demonstrate significantly higher ongoing pregnancy rates, clinical pregnancy rates, and implantation rates compared to those with persistent infection 7
Common Pitfalls
- Asymptomatic presentation leads to underdiagnosis—chronic endometritis often lacks specific symptoms despite significant reproductive impact 7, 6, 8
- Relying solely on culture misses nonculturable organisms; molecular methods provide more comprehensive pathogen identification 5
- Failure to screen for sexually transmitted infections in reproductive-age women delays diagnosis and allows progression to chronic disease 1, 2