Vulval abscess can be caused by actinomycetes infection, boils, folliculitis, cancer, Crohn’s disease, diabetes mellitus, gonorrhoea, staphylococcal infection, immune deficiency conditions, and most uncommonly by osteomyelitis. Osteomyelitis of the pubic symphysis is a rare disease. It is an infective inflammation of bone whose causative organisms differ according to the risk factors. Patients with recent pelvic surgery usually have polymicrobial infection, involving faecal flora. Staphylococcus aureus
is the major cause among athletes, whereas Pseudomonas aeruginosa
infection is the predominant pathogen in intravenous drug users.2 Klebsiella pneumoniae
infection has been reported in the diabetic patients.3
The clinical presentation of pubic osteomyelitis is similar to that of osteitis pubis, which is a self limiting condition.
Osteitis pubis is a non-infective inflammation of the symphysis pubis, without a distinct aetiology. It has often been reported following urological or gynaecological procedures, and is also associated with trauma, rheumatic disorders, pregnancy and parturition.
Both pubic osteomyelitis and osteitis pubis may present as abdominal, pelvic or groin pain. The most common complaint in both of these inflammatory diseases is pain with weight lifting. A waddling gait may be observed. On examination, hip motion will exacerbate pain, and its range may be restricted. The most obvious and specific finding is tenderness of the pubic bone in the superior or inferior pubic rami.
Historically, confusion has existed between osteitis pubis, pubic osteomyelitis, and septic arthritis of the symphysis pubis. All of these present with the same features. For unclear reasons, septic arthritis of the pubic symphysis is much more common in intravenous drug users, accounting for 9% of septic arthritis in the population. There is no significant radiographic differentiation between these three diseases.2
The biochemistry is normal or slightly inflammatory in osteitis pubis, but frankly inflammatory in osteomyelitis with increased leucocyte cell count, raised CRP and erythrocyte sedimentation rate.2
Aspiration is the ultimate diagnostic test. In cases of osteomyelitis pubis, culture of the aspirate will usually lead to the diagnosis, sometimes even after antibiotic treatment. Pelvic radiographs may show irregular borders over the pubic symphysis and rami. Varying degrees of articular surface irregularity, erosion, sclerosis, and osteophyte formation may be present. MRI may show bone marrow oedema in the pubic bones early in the course of osteitis pubis. The presence of fluid should raise suspicion for an underlying infection, such as osteomyelitis.
Distinguishing between osteitis and osteomyelitis pubis can be difficult with bone scans and MRI alone. Although a definitive diagnosis often requires biopsy and culture, a biopsy was not performed in the patient discussed here as the patient improved after starting on antibiotics. Lack of improvement with rest and non-steroidal anti-inflammatory drugs (NSAIDs) plus a good response to antibiotics confirmed the diagnosis of osteomyelitis pubis.
Osteitis is a self limiting condition and its treatment aims to reduce inflammation with rest and oral NSAIDs. Ice or heat may provide additional symptomatic relief. Since osteomyelitis is present in 97% of these patients with the same complaints, antibiotic treatment is recommended for a period of 8 weeks—the first 2 weeks intravenous and next 6 weeks oral.4
However, patients are often maintained on oral antibiotics for 3 months, especially if there is a long preceding history. Surgical debridement may be required if there is no response to medical treatment. Failure to identify the disease processes of osteomyelitis could lead to lifelong complications such as pelvic instability, etc.
One similar case has been reported to date, in India, involving a woman who presented with a genital sore, which was treated as chancroid. On further investigation, it proved to be the opening of a sinus secondary to chronic osteomyelitis of the pubic symphysis.5
- Consider osteomyelitis pubis as a cause of vulval abscess.
- Pelvic x-rays should be performed in a patient with recurrent vulval abscess.
- A multidisciplinary approach should be taken to the treatment of patients with recurrent vulval abscess.
- Prolonged antibiotic treatment is required in such cases.