What is an Infected Submucosal Myoma (Pyomyoma)?
An infected submucosal myoma, also called a pyomyoma, is a rare but serious complication where a uterine fibroid (leiomyoma) becomes infected and suppurative, typically following vascular compromise and subsequent bacterial seeding.
Pathophysiology
Pyomyoma develops when a fibroid undergoes necrosis followed by bacterial infection. The most likely mechanism involves vascular compromise of the fibroid tissue, creating an environment for bacterial colonization through direct extension, hematogenous spread, or lymphatic dissemination 1. The pathology reveals a degenerating fibroid with hemorrhage, necrosis, cystic degeneration, and inflammatory changes, with pus often containing polymicrobial organisms 1.
Clinical Context and Risk Factors
Pyomyoma occurs most commonly in specific clinical scenarios:
- Pregnancy and immediate postpartum period 2, 1
- Post-uterine artery embolization (UAE) - an extremely rare complication occurring in only 10 reported cases after UFE 3
- Postmenopausal status
- Recent uterine instrumentation
- Immunocompromised patients 1
However, spontaneous pyomyoma can occur even in nulligravid females without risk factors, though this is exceptionally rare 1.
Clinical Presentation
Patients typically present with:
- Fever that may be refractory to broad-spectrum antibiotics 2
- Abdominal pain (though notably, uterine tenderness may be absent 2)
- Signs of sepsis in severe cases
- Leukocytosis and hypotension 1
A critical pitfall: The causative organism may be resistant to standard antibiotics. For example, Mycoplasma hominis (which causes pyomyoma) is resistant to broad-spectrum penicillin antibiotics 2.
Diagnostic Approach
Diagnosis requires a high index of suspicion, as clinical presentation is often vague and imaging findings nonspecific 3, 4. When fever persists despite appropriate antibiotic therapy in a patient with known fibroids:
- CT or MRI imaging should be obtained to identify degenerative changes, gas within the fibroid, or fluid collections 3, 4
- Definitive diagnosis is only possible with surgery and pathological examination 1
- Consider additional imaging studies even when physical examination is unremarkable 2
Management Considerations
The traditional management has been hysterectomy with IV antibiotics 5, 4. However, fertility-sparing approaches are increasingly successful for submucosal pyomyomas 3, 5:
- Hysteroscopic transcervical resection is particularly suitable for submucosal pyomyomas due to favorable anatomical accessibility 3
- Conservative management combining IV antibiotics, image-guided drainage, and surgical debridement can preserve fertility 5
- Laparoscopic myomectomy has been successful in select cases 1
For ruptured pyomyoma with peritonitis, immediate surgical intervention with total abdominal hysterectomy, peritoneal irrigation, and drainage is necessary to prevent mortality from sepsis and respiratory distress syndrome 4.
Critical Clinical Pearls
- Pyomyoma should be considered in any patient with sepsis, known fibroids, and no other identifiable infection source 1
- Submucosal location offers the best opportunity for uterine-sparing management 3
- Delayed presentation can occur up to 42 days post-UAE 3
- Prompt recognition and treatment are essential to avoid major morbidity and mortality 3, 4