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An ex-intravenous drug user was admitted four times during a 2 year period from December 2006, with the same complaint of vulval abscess which required repeat incision and drainage procedures. In January 2009, a pelvic x-ray showed widening of the symphysis pubis, marginal irregularities, and severe erosive changes which were consistent with pubic osteomyelitis. She was treated with intravenous ciprofloxacin and clindamycin for 2 weeks and was discharged on oral antibiotics for 6 weeks. She recovered well and her condition has significantly improved with no recurrent infection so far. She is now being followed up every 4–6 weeks at the orthopaedics outpatient clinic.
Although pubic osteomyelitis is an uncommon cause of the common condition vulval abscess, it accounts for only 2% of all osteomyelitis of bone. Groups at risk include intravenous drug users, patients with pelvic malignancy, diabetes, following sports injury, surgery, after dental extraction1 and patients who have undergone urological or gynaecological procedures such as female incontinence surgery. It presents with significant diagnostic and treatment challenges. Pelvic x-ray can diagnose this condition and prevent further damage to the pelvis, which may result in pelvic girdle instability and could have a long term impact on the quality of life. We believe it is important to alert physicians and surgeons to this unusual presentation of pubic osteomyelitis in the gynaecology clinic.
A 48-year-old woman, menopausal for 2 years, had been suffering from recurrent vulval abscess since December 2006. She is an ex-intravenous drug user; the last time she injected a drug was December 2006. The infection started with fluctuant swelling of her right labia, following injecting drugs in the right groin and mons pubis, measuring 10 cm × 12 cm with no draining sinuses, which was initially treated with oral amoxicillin–clavulanic acid (Augmentin). The initial vulval abscess seemed to be an extension of local infection relating to drug injecting behaviour, with secondary spread to the pubic bones causing osteomyelitis. At first, the swelling responded but then recurred within 4 months from the onset of her first symptoms. Though she was managed with intravenous antibiotics (teicoplanin, metronidazole, and ciprofloxacin), the swelling did not resolve and needed incision and drainage. Thereafter, the patient was admitted four times within a period of just over 2 years with the same complaint, and needed repeat incision and drainage. Finally in January 2009, she was readmitted to the gynaecology department with pain and swelling over the right labia and mons pubis measuring 5 cm × 6 cm.
On examination, the patient was apyrexial, haemodynamically stable, her abdomen was soft and non- tender, and her chest was clear on auscultation. There was erythema and induration over the mons pubis. She had suprapubic pain and tenderness which increased on weight bearing, but no inguinal lymphadenopathy was noted. She was hepatitis C PCR positive, but hepatitis B and HIV negative. She received treatment with interferon in 2003 and is now followed up annually at the gastrointestinal clinic. She was thin and malnourished.
Blood biochemistry showed elevated C reactive protein (CRP) value of 116 mg/l and a white cell count of 13.4×109/l with polymorphonuclear leucocytosis. Because of chronic hepatitis C she had deranged liver function tests (LFTs), and liver ultrasound showed mild fibrosis. Blood cultures did not show any evidence of bacteraemia. Cultures from the abscess did not show any growth of any microorganisms, the reason being that she had been intermittently on antibiotics. Perianal ultrasound confirmed significant subcutaneous abscess collection. On pelvic x-ray there was widening of the symphysis pubis, and marginal irregularities suggesting severe erosive changes which were consistent with pubic osteomyelitis (fig 1). Subsequent blood tests showed a decrease in CRP and white cell count, and blood cultures were negative. A repeat pelvic x-ray after a month showed the same picture, although the suprapubic pain and tenderness had resolved.
After discussions with the microbiology team, the patient was treated with intravenous ciprofloxacin and clindamycin for 2 weeks. She was discharged on oral antibiotics for 6 weeks and a follow-up in the outpatient was arranged.
Following the course of antibiotics the patient recovered well and her quality of life is much better at present. There has been no recurrence so far. She is followed up regularly in the orthopaedic clinic. Her CRP value and white cell count are now normal.
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
Competing interests: None.
Patient consent: Patient/guardian consent was obtained for publication.