Recurrent Pelvic Abscess and Osteomyelitis in an 82-Year-Old Man, Osteomyelitis Pubis with Urinary Tract–Urinary Fistula

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 Osteomyelitis pubis with urinary tract urinary fistula

Osteomyelitis pubis with urinary tract–urinary fistula is a rare but serious condition that involves infection of the pubic bone (osteomyelitis) complicated by an abnormal fistulous communication between the urinary tract and surrounding tissues, often leading to further infection and complex urological issues.

1. Cause and Etiology

Osteomyelitis pubis is an inflammatory bone infection of the pubic symphysis and adjacent rami. When complicated by a urinary tract–urinary fistula, the etiology typically involves:

  • Iatrogenic injury: Pelvic surgeries (e.g., prostatectomy, cystectomy, urethral surgery), catheterization, or radiation therapy can damage the urinary tract and pubic bone, predisposing to infection and fistula formation.
  • Trauma: Pelvic fractures, especially those involving the pubic symphysis, can cause both bony infection and urinary tract disruption.
  • Chronic urinary tract infections: Especially in patients with neurogenic bladder or chronic catheterization, bacteria can spread from the bladder or urethra to adjacent bone.
  • Postoperative complications: Following urological procedures, particularly in elderly or immunocompromised individuals.
  • Osteomyelitis extends from infected pressure ulcers (less common) in debilitated patients.

2. Pathophysiology

The pathophysiological sequence includes:

  • Initial infection: Bacterial seeding of the pubic symphysis can occur hematogenously or via direct extension from the urinary tract.
  • Bone necrosis and abscess formation: Infection causes inflammation, edema, and osteolysis.
  • Fistula formation: Chronic infection and necrosis may result in a fistulous tract between the urinary tract (urethra, bladder) and pubic symphysis or surrounding soft tissue.
  • Ongoing contamination: Urine leakage into infected tissues perpetuates infection and impairs healing.
  • Chronic osteomyelitis: Establishes a persistent inflammatory cycle, possibly with sequestrum formation and sinus tracts.

3. Epidemiology

  • Incidence: Rare; exact epidemiologic data is limited due to underreporting.
  • Risk groups:
    • Males > females (due to higher rates of pelvic urological surgeries in men).
    • Elderly patients with comorbidities (e.g., diabetes, malignancy, chronic catheter use).
    • Postoperative or post-traumatic patients.
    • Athletes (non-infectious osteitis pubis may precede infection).

4. Clinical Presentation

Patients may present with:

  • Pubic or suprapubic pain: Worsened by walking or hip movement.
  • Difficulty ambulating or antalgic gait.
  • Urinary symptoms:
    • Dysuria, hematuria, frequency.
    • Urine leakage from unexpected sites (in case of external fistula).
  • Systemic signs:
    • Fever, chills, and malaise in the acute phase.
  • Pelvic tenderness: On examination.
  • Chronic draining sinus: Over the pubic region in longstanding cases.

5. Imaging Features

Radiologic evaluation is crucial. Modalities include:

a. Plain Radiography:

  • Often normal early.
  • Later findings: Erosions, osteolysis, periosteal reaction.

b. MRI (modality of choice):

  • Marrow edema (hypointense on T1, hyperintense on T2/STIR).
  • Bone destruction.
  • Abscess formation.
  • Fistulous tract: Enhanced linear track from bladder or urethra to pubic bone.

c. CT Scan:

  • Better for cortical bone erosion.
  • Identifies sequestrum, gas formation, or abscess.
  • Can visualize fistula if contrast extravasates.

d. Fistulography or CT Cystogram:

  • Demonstrates communication between the urinary tract and bone/soft tissue.
  • Helps in preoperative planning.

e. Ultrasound:

  • May detect fluid collections or sinus tracts.

6. Microbiology

Common organisms:

  • Gram-negative uropathogens: Escherichia coli, Proteus, Klebsiella.
  • Gram-positive cocci: Staphylococcus aureus (especially MRSA).
  • Anaerobes and mixed flora: In chronic or polymicrobial infections.
  • Mycobacterium tuberculosis: In endemic areas or immunosuppressed patients.

Cultures should be obtained from:

  • Blood.
  • Urine.
  • Bone biopsy or surgical debridement.

7. Treatment

Management is multidisciplinary, involving urology, infectious disease, and orthopedic surgery.

a. Antibiotic Therapy:

  • Empirical coverage: Broad-spectrum IV antibiotics targeting uropathogens and bone infections.
  • Targeted therapy: Based on culture and sensitivity, typically for 6–12 weeks.

b. Surgical Management:

  • Fistula repair: Requires closure of urinary fistula, often with tissue flaps.
  • Bladder diversion: Temporary (suprapubic catheter) or permanent in severe cases.
  • Debridement: Removal of necrotic bone, sinus tracts, and abscesses.
  • Bone stabilization: Rarely needed, but may involve reconstruction or fixation.

c. Urinary Diversion:

  • Suprapubic or percutaneous nephrostomy to rest the bladder and allow healing.

d. Hyperbaric Oxygen Therapy:

  • Occasionally used to promote bone and soft tissue healing in chronic cases.

8. Prognosis

Prognosis depends on:

  • Timely diagnosis: Delayed treatment increases the risk of chronic infection.
  • Extent of fistula and bone involvement.
  • Patient comorbidities: Diabetes, immunosuppression, prior radiation.
  • Success of surgical intervention.
  • Response to antibiotics.

With aggressive treatment, outcomes can be favorable, but chronic osteomyelitis or fistula recurrence is possible. Failure to address the underlying urinary source can result in persistent or recurrent infection.


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Case Study: Recurrent Pelvic Abscess and Osteomyelitis in an 82-Year-Old Man 

Osteomyelitis Pubis with Urinary Tract–Urinary Fistula

doi:10.1259/bjrcr.20210217

Abstract

Prostate cancer accounts for 13% of all new cancer diagnoses in the UK. Urosymphyseal fistulas are a rare complication that can occur post-radiotherapy and surgery for prostate cancer. Patients often present with non-specific symptoms such as suprapubic tenderness, poor mobility, recurrent urinary infections, and difficulty passing urine. These can be difficult to diagnose clinically and extremely problematic and debilitating for patients. The management of these patients is often complex and requires input from urology, orthopaedics, and microbiology. At present, there are no clear guidelines for diagnosing these conditions. Recommended investigations include blood tests, urine culture, and imaging. The preferred imaging modality is pelvic MRI. This article explores three rare cases of such complications and the classic imaging findings on CT and MRI to aid the diagnosis of urosymphyseal fistula.

Osteomyelitis Pubis with Urinary Tract–Urinary Fistula

History and Imaging Findings

  1. A 78-year-old man was admitted with severe lower abdominal pain and a 3 cm tender, irreducible lump palpable in the suprapubic region.

  2. He had a prior history of prostate cancer (stage T3 b, Gleason score 4 + 3 = 7) and had undergone radical whole-pelvis radiotherapy.

  3. A CT scan was performed for further evaluation.

Quiz 1:

  1. There is definitive evidence of pubic osteomyelitis on the CT scan.
     (1) True
     (2) False

Explanation: The CT scan revealed cortical bone destruction consistent with osteomyelitis, which is a definitive radiologic sign of bone infection. This supports the diagnosis of pubic osteomyelitis.

  1. Considering the clinical history, an MRI should be performed to evaluate for a urosymphyseal fistula.
     (1) True
     (2) False

Explanation: Given the patient's history of pelvic radiotherapy and the presence of suprapubic fluid collections extending toward the anterior bladder region, a urosymphyseal fistula is suspected. MRI is the most sensitive modality to detect soft tissue abnormalities and fistulous tracts, and is therefore appropriate.

Findings and Diagnosis

Findings:
Initial CT imaging demonstrated an irregular fluid collection with peripheral rim enhancement extending into the prevesical (retropubic) fat. Cortical bone destruction of the pubic symphysis was also noted, consistent with osteomyelitis.

The patient subsequently underwent pelvic MRI, which demonstrated low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. The short tau inversion recovery (STIR) sequence revealed signal abnormalities in both pubic bones adjacent to the symphysis pubis, with inflammatory changes extending into the parasymphyseal musculature, including the obturator and adductor muscle groups (highlighted by the red box – “Lorax sign”).

Additionally, multiple soft tissue fluid collections and abscesses were identified on MRI. Following administration of intravenous contrast, enhancement consistent with osteomyelitis was observed, particularly involving the affected pubic bones and surrounding soft tissues.

These findings are suggestive of a fistulous tract extending from the prostate to the pubic symphysis, potentially leading to osteomyelitis and osteonecrosis. On closer inspection of the imaging, the fistula was seen to extend to the base of the penis, with contrast enhancement observed in the perineal region.

Differential Diagnosis

  • Pubic bone osteomyelitis

  • Abscess

  • Urosymphyseal fistula

  • Metastasis causing bony destruction

Final Diagnosis
Urosymphyseal fistula

Treatment

Management of such cases is often complex and requires a multidisciplinary approach, involving urology, orthopedic surgery, and microbiology.

While antibiotic therapy is initiated to prevent urosepsis, conservative management alone rarely succeeds, and surgical intervention is frequently necessary.
Surgical procedures may include resection of infected bone, fistulectomy, and urinary diversion.
Depending on the case, complete cystectomy with ileal conduit formation may be performed.

Discussion

Osteomyelitis Pubis with Urinary Tract–Urinary Fistula
Osteomyelitis pubis secondary to a urosymphyseal fistula is a rarely reported condition, with fewer than 50 cases documented in the literature.
It represents an uncommon complication of prostate surgery and radiation therapy.
Accurate diagnosis relies heavily on recognizing the clinical presentation and imaging features.

Patients often present with nonspecific symptoms, which can lead to misdiagnosis, especially if they have not initially sought urological consultation.
Although the exact pathophysiology of urosymphyseal fistulas remains unclear, accumulating case data have led to a better understanding.
Urosymphyseal fistulas after prostate cancer treatment have been associated with prostatectomy followed by endoscopic management, transurethral resection of the prostate (TURP), and pelvic radiotherapy.
Surgical and radiation treatments increase the risk of fibrotic stricture formation.
As a result, endoscopic procedures such as cystoscopy are often employed to manage urethral strictures and bladder outlet obstruction.

However, these interventions may contribute to urogenital fistula formation, leading to secondary pubic osteomyelitis, likely due to urine sequestration near the symphysis, providing a route for bacterial contamination.

Imaging for osteomyelitis often requires a combination of modalities for accurate diagnosis, including plain radiographs, CT, and MRI.
Nuclear medicine offers high sensitivity but is often nonspecific.
CT scanning provides excellent multiplanar reconstruction, allowing detection of even subtle osseous changes.
MRI is considered the most sensitive and specific imaging modality, as documented in the literature, and is less invasive compared to retrograde studies.

Learning Points

  • In any patient with a history of prostate cancer treated with surgery or radiation, urosymphyseal fistula or pubic osteomyelitis should be considered.

  • CT imaging is valuable for the early detection of bony involvement in osteomyelitis.

  • MRI is recognized in the literature as the most sensitive and specific imaging modality for diagnosing this condition.

References

 

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