Pubic osteomyelitis, also referred to as infective synchondritis, is an infectious inflammatory condition affecting the pubic bone and symphysis.

Predisposing factors include –
•Extremes of age [children and elderly] where staphylococcus is the main pathogen
•Post parturition
•Post genitourinary procedures
•Parenteral drug abusers
•Athletes
•Pelvic malignancies
Very occasionally it may occur without any underlying cause.

Organisms involved are: Staphylococcal auerus, Pseudomonas aeruginosa, Streptococcus pneumoniae, E.coli.

Most of the patients present with fever, pubic pain, waddling gait, hip and groin pain.

Ultrasound features-
• A soft-tissue mass with a heterogeneous echotexture and mixed echogenicity in the pre-vesical space, or the space of Retzius – suggestive of abscess.
• If the abscess is liquefied, it may show cystic areas in the center with no flow.
• The mass may show increased vascularity due to inflammation.
• Irregular margins of the bone in close proximity suggesting bony erosion or frank destruction may be noted.

Role of ultrasound:
1. Establish a diagnosis
2. Ultrasound guided biopsy/aspiration [for culture of the organisms] and therapeutic aspiration of the abscess.
3. Non-invasive follow up of the patients as this disease requires prolonged treatment.

Differential diagnosis: The most important and possibly the only differential that needs to be considered is osteitis pubis- this is a sterile, painful, inflammatory condition involving the pubic bone, symphysis and surrounding structures. The imaging appearance may be quite similar, with bone destruction seen in a few cases. It is however, self-limiting and responds to anti-inflammatory agents.

Management: Prolonged anti-microbial treatment with occasional surgical debridement and curettage required for complete cure.