Pus Proficiency: Understanding Purulent Drainage

Wound drainage management is an essential component of wound care. The presence of purulent drainage indicates infection and healing status. Non-healing wounds affect millions of individuals in the United States, impacting a significant portion of those over 65. Knowledge of the characteristics, implications, and proper management of purulent drainage is crucial for optimal wound healing.

Purulent Drainage: The Basics

Characteristics

Purulent drainage, or pus, is a thick, opaque fluid formed by the body as an inflammatory response to infection. It usually contains dead white blood cells, bacteria, tissue debris, and various proteins accumulated during the infection-fighting phase.

The appearance of pus varies from cream-colored to yellow-green, but it may be brown or pink-tinged depending on the presence of blood or other pathogens. There is almost always some odor – from slight to intense.

Mechanism

Pus formation begins as part of the body’s immune response to pathogen invasion. When bacteria breach the skin’s protective barrier, neutrophils (specialized white blood cells) are called into action. They engage in phagocytosis, consuming the invading pathogens and subsequently dying. The accumulation of these dead neutrophils with other debris creates the appearance of pus.

This process is called the inflammatory cascade:

• Pathogen invades, triggering an immune response
• Neutrophils migrate to the site
• Phagocytosis
• Dead neutrophils and debris accumulate
• Purulent drainage forms

Clinical Significance

The presence of pus usually indicates infection and requires medical attention—however, not all purulent drainage results from a serious infection. The context, quantity, and associated symptoms must all be considered.

Clinical indicators that treatment by a medical professional should be sought include:

• Volume changes. Any increase in the volume of pus is suspicious for the progression of an infection.
• Color transitions. Normal wound drainage is pale or has a slight hue. Purulent drainage is milky and thick. If the pus appears green, yellow, or brown, it indicates a progression of the infection.
• Consistency. Normal wound drainage is thin; purulent drainage is much thicker.
• Associated wound characteristics. Normal healing wounds should only have a mild odor, if any. Foul odors indicate the presence of infection. The skin around the wound may be warm and may have red streaks, which can point towards cellulitis.
• Systemic symptoms. Tenderness, fever, and elevated white blood cell count may be seen when infection is present.

Assessment and Management of Purulent Drainage

Visual examination

As with any wound, the basic principles of examination apply:

1. Identify the wound type and cause.
2. Evaluate the patient’s overall health. This will indicate the healing potential. Certain groups, such as the elderly, diabetics, and immunocompromised individuals, are prone to delayed healing of all types.
3. Document the wound’s characteristics, including the size, depth, and location.
4. Check for infection. Signs of exudate are not necessarily indicative of infection. The appearance and type of drainage should be documented. There are several types of drainage to look out for.
   • Sanguineous: Appearing during the first few hours of injury, it contains primarily fresh blood and is pink or bright red. In a full-thickness or partial-thickness wound, this may last for a few days after an injury but should decrease rapidly.
   • Serous: This exudate is light and clear and consists of serous fluid. It is often seen with venous insufficiency ulcers and partial-thickness wounds, but it does not give off an odor. It is considered beneficial as it contains proteins, sugars, and leukocytes that facilitate healing. This fluid is produced during the inflammatory stage and is normal. However, an excessive amount that soaks a dressing several times a day may indicate edema or infection.
   • Serosanguineous: With a combination of serous and sanguineous drainage, serosanguineous is the most common type of discharge. It is usually pale and thin in appearance with a reddish tinge. It is frequently an indicator of a clearing infection.
   • Serous purulent drainage: This thin and pale drainage is composed primarily of white blood cells and appears during the inflammatory wound healing stage in the initial 48-72 hours after an injury.
5. Make sure the wound is progressing normally through the wound healing stages.
   • Hemostasis – Fibrin clot forms to stop acute bleeding
   • Inflammation – Neutrophils and macrophages are activated to fight off invading microbes, releasing cytokines and other inflammatory agents
   • Proliferation – Cell growth and activity produce new skin and blood vessels
   • Remodeling – The skin is healed; the extracellular matrix remodels itself
6. Reassess the wound regularly. All wounds, but particularly infected wounds, should be regularly reassessed by the care team. Any distinct changes should be noted, and the appropriate healthcare team member should be notified immediately.

Measurement and Diagnosis

Culturing wounds

Optimal diagnosis and management of infections are crucial for healing. All open wounds are colonized with bacteria, and wound healing can still occur despite their presence. A wide variety of aerobic and anaerobic bacteria can contaminate wounds. However, it is not the number of bacteria that matters but the bacterial species.

Two techniques for swabbing the wound for culture have been used: the Levine technique and the Z technique. With the Levine technique, the specimen is obtained from a much more limited area, but the swab is rotated with enough pressure to express fluid from the wound. Recent studies have shown that the Levine technique is preferred for obtaining bacterial cultures.

With the Z technique, the swab is rotated between the fingers and manipulated in a zigzag fashion across the wound without touching the edges.

Other Diagnostic Methods

While a culture swab remains the primary method for diagnosing bacterial colonization of the wound, other methods may be needed depending on the patient, location, and severity of the wound.

• Wound biopsies can be invaluable for diagnosing invasive burn wounds. If there are bacteria in the deep dermis on biopsy, it correlates with the risk of sepsis in a burn patient. A bone biopsy is the gold standard for diagnosing osteomyelitis.
• Laboratory studies can be useful tools for managing chronic wounds; however, they are often not necessary, as routine blood work is not required. Some studies that may be used for certain patients include serum prealbumin for evaluating nutritional status, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), which can help confirm the diagnosis of osteomyelitis or be used to monitor treatment efficacy.
• Ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI) may be useful for delineating fluid collections, necrotic tissue, or inflammation in select circumstances.

Assessment and Documentation

As wounds are often cared for by a multidisciplinary team, consistent documentation is necessary to communicate with the various members of the team. While there are many ways to document wounds, there are a few standardized tools that may be useful in your practice. These may be helpful in both the initial diagnosis of the wound, as discussed above, and in subsequent check ins to measure progress.

Bates Jensen Wound Assessment Tool

This method looks at 15 items for wound measurement and observations. Of the 15 items, 13 are scored: size, depth, edges, undermining, necrotic tissue type and amount, exudate type and amount, skin color surrounding the wound, peripheral edema and induration, granulation tissue, and epithelialization. The two non-scored items are the location and shape of the wound. Each scored item ranges from one to five on a scale, indicating the severity level, with five being the most severe. These items are added for a maximum score of 65. The total score can be plotted to track progression.

TIMERS

This assessment tool does not use a scale but relies on the observation of the caregiver. The six categories included:

1. Tissue management
2. Infection/inflammation
3. Moisture
4. Epithelial edge
5. Repair/regeneration
6. Social factors

Providers should rely on their experience and observation to assess wounds in these areas when using this assessment method.

REEDA

While this tool is primarily used for perineal wounds, its criteria (redness, edema, ecchymoses, discharge, and approximation) have been used by some wound experts in assessing other wounds. This method also relies on the judgement of the clinician to assess the wound.

Software can also be helpful in assessing and documenting wounds. With AI-powered wound imaging platforms, images of wounds can be compared to a database of millions of other wound images, helping providers make more accurate diagnoses and better track wound healing and treatment plans.

Treatment for Purulent Drainage

Treatment for purulent wounds must be instituted promptly to avoid further complications. Options will vary based on size, location, stage of wound healing, and the patient’s overall health. The two key steps are to prevent further damage and keep the area clean to avoid further contamination.

Dressing selection and cleansing methods will also depend on the type of infection. Another step in the treatment plan is assessing the patient’s overall risk. For instance, wounds with venous insufficiency will also require elevation and compression to manage drainage. Negative pressure wound therapy may be used for deeper or chronic wounds.

Antibiotics may be prescribed, and in cases where an abscess develops, drainage or surgical debridement may be necessary to facilitate recovery. 

Complications

If a person does not receive treatment for a wound infection, the infection can spread to other parts of the body. 

Cellulitis is an illness that affects the skin’s deeper tissues and layers. The typical presentation is warmth and red streaks at the wound site. Fever, lightheadedness, nausea, and vomiting are possible additional symptoms. 

Osteomyelitis is a bacterial infection of the bone that causes pain, swelling, and redness in the surrounding area. Other symptoms that osteomyelitis patients may experience include fever and fatigue. 

Sepsis occurs when the bacteria enter the bloodstream, causing widespread infection – this requires immediate hospitalization.

Necrotizing soft tissue wounds are rare, but when they occur, they are life-threatening emergencies. They are categorized based on the layer of soft tissue involvement and may be necrotizing cellulitis, necrotizing fasciitis, or necrotizing myositis. 

The hallmarks of the disease, including bullae, crepitus, gas/emphysema on X-ray, hypotension, and skin necrosis, are seldom seen at presentation. The diagnosis remains primarily clinical.

The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) has been used to distinguish between necrotizing and non-necrotizing skin and soft tissue infections. It was developed in 2004 and has shown promising results in predicting the severity of these infections. Its parameters include :

• C-reactive protein
• White blood cell count
• Hemoglobin
• Sodium
• Creatinine
• Glucose

However, if there is high suspicion of necrotizing fasciitis, surgical debridement should proceed without delay.

Multidisciplinary Approach

Infected wounds require care and attention from multiple team members. This may involve specialists beyond the wound care team, including surgeons, infectious disease specialists, and physical therapists. One crucial member often overlooked is the patient, since patient involvement  in their own care can offer several benefits.

Improved Self-Management

Patient education allows each individual to participate actively in their care. Understanding the nature of the wound and the importance of wound hygiene can improve healing. Those who are better informed are more likely to comply with the recommended practices.

Prevention of Complications

Proper wound care can reduce complications such as infections and delayed healing. Educating patients on the signs of infection and other complications will often lead to earlier intervention.

Healthy Lifestyle Choices

It is an optimal moment to inform patients about the impact of lifestyle choices on healing. Counseling them about nutrition, smoking cessation, and managing chronic conditions such as diabetes can significantly influence the success of the treatment.

Superior Surgical Wound Care

In this category, the basics, such as keeping the incision site clean and dry, apply to nearly all surgical wounds. To help with healing, each patient will be provided with wound care specific to their situation.

Improved Communication

When patients are better educated about the process, they become better at communicating their progress to their healthcare providers. Clear communication ensures patients understand their treatment plans, medications, and follow-up appointments. This collaboration is essential for recovery.

Reduced Healthcare Costs

Better-informed patients have fewer complications, hospital readmissions, and additional treatments.

Managing Purulent Drainage: Today and in the Future

Much purulent drainage wound care remains basic: assess, culture, and manage the wound with proper cleaning, dressing, and other topical or systemic treatments as needed. Treatment of these wounds requires a team approach for optimal results. Other treatments are being used to accelerate healing, such as bacteriophage treatment, growth factor applications, bioengineered tissues, and stem cell treatments. These and other novel dressings offer promising adjuncts to treating these wounds.