Terminology and Diagnosis
A pinpoint, non-healing wound in the sacrum is most accurately termed a Stage III or Stage IV pressure injury (also called pressure ulcer), depending on the depth of tissue involvement. 1 The term "pressure injury" or "pressure ulcer" is preferred over outdated terminology such as "decubitus ulcer" or "bedsore." 1
Classification Based on Depth
The specific stage depends on what tissue layers are visible or palpable:
- Stage III pressure injury: Full-thickness tissue loss exposing subcutaneous fat, but bone, muscle, and tendon are not visible or directly palpable 1
- Stage IV pressure injury: Full-thickness tissue loss with exposed bone, muscle, ligament, or tendon, which may involve undermining, tunneling, and osteomyelitis when bone is exposed and infected 1
Important caveat: If the wound is covered by eschar or slough, it must be classified as "unstageable" until debrided, as the true depth cannot be determined. 1
Why Sacral Wounds Are "Pinpoint" and Non-Healing
Sacral pressure injuries commonly present with a deceptively small surface opening despite extensive underlying tissue damage. 2 This occurs because:
- The sacrum is the most common location for pressure ulcers, accounting for 39-40% of all pressure injuries 1, 3
- These wounds frequently develop sinus tracts (tunneling) beneath the skin surface, creating a small entry point with large, deep basement involvement 2
- The lower sacral segments (below S3/S4) have subcutaneous bone with poor intrinsic blood supply, predisposing to deep tissue injury 4
Clinical Assessment Requirements
Complete documentation should include: 1
- Stage (III or IV based on deepest tissue involvement)
- Wound dimensions (length, width, depth)
- Amount and type of necrotic tissue present
- Exudate characteristics (amount, color, consistency)
- Surrounding skin condition
- Presence of undermining or tunneling 2
Risk Factors in This Population
Patients with sacral pressure injuries typically present with: 3, 5
- Advanced age (median 76 years, with 47% between 60-80 years and 37% ≥80 years)
- Limited mobility or immobilization
- Cardiovascular disease (72% of cases)
- Neurological diseases (46% of cases)
- Nutritional deficiencies: low albumin (mean 2.56 g/dL), anemia (mean hemoglobin 10.43 g/dL)
- Diabetes (18% of cases)
Evaluation for Underlying Osteomyelitis
Critical consideration: When bone is exposed or palpable in a Stage IV sacral pressure injury, pelvic osteomyelitis (POM) must be suspected. 4 The lower sacral segments are particularly vulnerable because the bone is subcutaneous with poor blood supply. 4
Imaging approach for suspected bone involvement: 4
- MRI without and with IV contrast is the preferred initial imaging (sensitivity 96%, specificity 94% for spine infection)
- CT with IV contrast can evaluate osseous detail and paraspinal soft tissue abnormalities (sensitivity 79%, specificity 100%)
- Plain radiographs are insensitive for early osteomyelitis
Prognosis and Mortality
Important prognostic information: 3
- Mortality in hospitalized patients with pressure injuries is 37%, with 23% dying within the first 7 days due to critical underlying conditions
- Sacral ulcers have lower recurrence rates after surgical repair compared to ischial or trochanteric ulcers 1
- Non-healing is associated with lower hemoglobin, poor mobility, inability to take oral nutrition, and lower mean arterial pressure 5