Tubo-ovarian abscess

A tubo-ovarian abscess (TOA) is one of the complications of pelvic inflammatory disease (PID).

Clinical presentation

Patients typically present with fever, elevated WBC count, lower abodminal-pelvic pain, an adnexal mass(es) and / or vaginal discharge. Fever and leukocytosis may sometimes be absent.

Pathology

Tubo-ovarian abscess are often polymicrobial with a preponderance of anaerobic organisms ⁹.

Radiographic features

The clinical context is extremely important in radiological interpretation.

Plain film

• plain film features are non specific
• may show evidence of a soft tissue density mass
• there may be an added adynamic ileus

Pelvic ultrasound

This is the initial imaging modality of choice

• often shows complex retro-uretine / adnenal mass(es)

CT

Can be helpful adjunct to ultrasound especially in determining the extent of disease ³. 

• usually shows thick walled fluid density pelvic masses. 
• a tubular configuration is more conclusive of a pyosalpinx.

MRI

Can be useful especially when sonography is inconclusive or non-diagnosticor if gas content is difficult to be differentiated from bowel gas ⁵.

Typically seen as thick walled fluid filled pelvic mass(es)¹²

• T1 - abscess contents typically hypo-intense
• T2 - abscess contents typically of heterogenous signal or hyper-intense

Complications

• rupture of abscess

Treatment

Initial treatment can be with antibiotictherapy. Radiological guided drainage or surgery may be required patients resistant to antibiotic treatment. Drainage may be performed from a trans-vaginal, trans-gluteal, or trans-abdominal approach dependant on patient and operator preference ⁴.

Differential diagnosis

Clinical features of infection is a key to aid diagnosis as a number of other pathologies can give similar appearances ¹.

• pelvic malignancy
• complex diverticular abscess
• complex appendiceal abscess
• pelvic endometriosis