What are the causes of a tuboovarian abscess?

Causes of Tuboovarian Abscess

Tuboovarian abscess is caused by ascending polymicrobial infection from the lower genital tract, most commonly involving sexually transmitted pathogens (Neisseria gonorrhoeae and Chlamydia trachomatis) along with anaerobic bacteria, gram-negative facultative bacteria, and streptococci. 1

Primary Causative Organisms

Sexually Transmitted Pathogens

• Chlamydia trachomatis has been recovered from the cervix of 5-39% of women with pelvic inflammatory disease (PID), with serologic evidence found in 20-40% of women with PID history 2
• Neisseria gonorrhoeae shows isolation rates from the cervix ranging from 27-80% among women with PID 2
• Between 10-40% of women with untreated gonococcal or chlamydial cervicitis develop clinical symptoms of acute PID, which can progress to tuboovarian abscess 2

Anaerobic and Facultative Bacteria

• Anaerobic bacteria are isolated from the upper genital tract of 25-50% of women with acute PID and include: 2

  • Bacteroides fragilis and Bacteroides bivius (particularly important as they cause tubal and epithelial destruction) 2, 3
  • Peptostreptococcus species 2
  • Peptococcus species 2

• Facultative bacteria commonly involved include: 2

  • Gardnerella vaginalis 2
  • Streptococcus species 2
  • Escherichia coli 2, 4
  • Haemophilus influenzae 2

Bacterial Vaginosis Connection

• Bacterial vaginosis (BV) has been identified as an antecedent to lower genital tract infection leading to polymicrobial acute PID and subsequent tuboovarian abscess 2
• The organisms involved in BV mirror the nongonococcal, nonchlamydial bacteria frequently isolated from the upper genital tract 2

Pathogenesis and Risk Factors

Mechanism of Infection

• Direct canalicular spread from the endocervix to the endometrial and fallopian tube mucosa is the primary route 2
• Noncanalicular spread via parametrial lymphatics can also occur 2

Contributing Factors

• Uterine instrumentation (particularly intrauterine device insertion) facilitates upward spread of vaginal and cervical bacteria 2
• Hormonal changes during menses lead to cervical alterations resulting in loss of mechanical barrier protection 2
• The bacteriostatic effect of cervical mucus is lowest at the onset of menses 2
• Retrograde menstruation may favor ascent to the tubes and peritoneum 2

Uncommon Causative Organisms

Rare Pathogens in Special Populations

• Pasteurella multocida has been reported in non-sexually active women with animal exposure (cat scratches), causing tuboovarian abscess through hematogenous spread 5
• Escherichia coli via suspected bowel translocation has been documented in virginal adolescent females, representing an extremely rare etiology 4

Clinical Implications

Polymicrobial Nature

• Tuboovarian abscess is characteristically polymicrobial with a preponderance of anaerobic organisms, regardless of whether an intrauterine device is present 3
• This polymicrobial nature necessitates broad-spectrum antimicrobial coverage including anaerobes, as organisms like Bacteroides fragilis cause significant tubal and epithelial destruction 1, 3

Key Pitfall to Avoid

• Never assume tuboovarian abscess is solely due to sexually transmitted infections—consider rare pathogens in non-sexually active women presenting with acute febrile pelvic illness, particularly those with animal exposure or potential bowel pathology 5, 4