Understanding Seropurulent Drainage

Whether seropurulent or serous, it can be challenging to make a distinction between the different types of wound drainage, also known as exudate. But recognizing the type of wound drainage present and knowing how to treat it are essential wound care skills.

We spoke with two wound care experts on how to identify and treat one exudate type known as seropurulent wound drainage.

What is seropurulent drainage?

Seropurulent wound drainage signifies a characteristic change from standard wound drainage, said Kristie Shytle, MSN, RN, AGNP-BC, a nurse practitioner at the Duke Raleigh Hospital Wound Healing Center in Raleigh, North Carolina. “Its presence can indicate the beginning of an acute infection but can also be a clinical sign of a treated infection improving,” Shytle said.

Wound drainage is a spectrum and has multiple characteristics, said John Gambol, MD, Lead Physician at the Wound Care Centers at USC Verdugo Hills Hospital in Glendale and Placentia Linda Hospital in Placentia, and Medical Director for Wound Care Advantage, a California-based wound care services company.

The classification and quantification between wound drainage that is serous, serosanguineous, seropurulent, and purulent can be very subjective, he said.

“A change in drainage should prompt one to investigate why there was a change,” Gambol said. “While a change may mean there is poor edema control, it may also indicate the presence of infection.” He added that if any suspicious characteristics are present, a culture should be obtained.

Gambol, who is board-certified in emergency, undersea and hyperbaric medicine, and wound care, said that when there is significant bacterial colonization of a wound or a localized wound infection, the drainage is usually classified as seropurulent.

Seropurulent drainage can develop in any wound. However, it is most seen in venous leg ulcers with gram-negative colonization, said Gambol. “Occasionally a gout wound with tophi can develop seropurulent or purulent drainage secondary to the immune response from the gout.”

Wounds of full-thickness injury are at the highest risk of infection, added Shytle.

Physical characteristics

Seropurulent wound drainage can have a variation of characteristics as follows, said Shytle.

• Color: Can range from yellow (darker than serosanguineous drainage), tan, or even light green
• Consistency: Thin
• Odor: May be malodorous or even “sweet,” such as with Pseudomonas — though some wounds may not have any odor at all when in the early stages of infection.

Seropurulent drainage is often yellow, said Gambol. If seropurulent drainage is green, it raises suspicion the wound has a Pseudomonas colonization or infection.

Seropurulent vs. purulent

When caring for patients with wounds, it’s helpful to know how seropurulent differs from purulent drainage.

“Seropurulent drainage is lighter in color and thinner than purulent drainage. Pus or purulent (thick, milky) drainage is an indication of an active infection,” said Shytle.

Additionally, Shytle highlighted the physical characteristics of purulent wound drainage:

• Color: Milky white, tan, brown, milky yellow, or green
• Consistency: Thick, with moderate to copious amount of drainage
• Odor: Malodorous

Gambol added that an odor may or may not be present with an infection. “Purulent drainage with a foul odor is often consistent with an anaerobic infection,” he said.

Although odor can help guide treatment, odor alone should not be relied upon for a diagnosis. If any suspicious odor is present, obtain a culture, he suggested.

“Consider obtaining imaging studies to look for deep abscess or fluid collection that is not apparent on physical examination,” said Gambol about purulent wounds.

Proper seropurulent exudate treatment

Treatment of seropurulent drainage depends on the wound location, size, and amount of drainage, according to Gambol.

“In wounds with seropurulent or purulent drainage, or an increase in serous drainage, wound cultures are medically necessary to determine the bacterial etiology present and to guide optimal therapy,” he said.

Pseudomonas is a common cause of seropurulent drainage, he added. “It’s essential to know if the Pseudomonas is resistant or sensitive to the quinolone class of antibiotics, such as ciprofloxacin or levofloxacin,” he recommended.

It’s key to remember that wound infections can frequently be treated or managed with a topical antibiotic or antimicrobial agents, if there is no sign of systemic infection or sepsis present, Gambol said.

“If the patient is a low risk for serious infection such as cellulitis or a systemic infection, consider wound care with topical products that can reduce critical bacterial colonization and infection,” added Shytle.

Wound cleansers such as hypochlorous acid solutions break down the membrane of bacterial cell walls and are generally non-cytotoxic unlike alcohol and hydrogen peroxide, she said.

“Use of topical dressings that contain silver can also disrupt the bacterial cell wall and membrane leading to bacterial cell death. There are many silver alginate dressings that effectively reduce bacterial presence and manage the drainage away from the wound bed,” Shytle said.

Challenges to navigate

According to Gambol, wounds with light and moderate drainage are easier to manage than wounds with heavy drainage.

However, it’s important to remember that wound size is also a major factor. “It’s easier to obtain and utilize antimicrobial dressings with wounds smaller than 10 cm by 10 cm,” Gambol said. “With larger wound sizes, obtaining adequate amounts of antimicrobial dressings can be cost prohibitive.”

“In chronic wounds, which are wounds that have not shown expected healing outcomes or have been present for four months or longer, bacterial contamination and colonization are higher, so wound cultures may not always be helpful in identifying the bacterial culprit,” added Shytle.

Frequently, wounds will become colonized by bacteria or a low-grade wound infection that can progress to an infection of the surrounding skin and soft tissue, Gambol said.

“Other disease processes that can cause seropurulent drainage without infection should be considered if drainage persists and cultures are negative,” he said. “Pyoderma should be considered as one of these. Pyoderma gangrenosum is frequently complicated by gram-negative bacterial colonization.”

Gambol noted that one frequent mistake when treating a leg wound with heavy drainage is to use more dressings to help better absorb the drainage. “Without adequate compression, it leads to increased moisture of the wound bed and frequently wound deterioration,” he said.

When treating drainage in a leg wound, it’s important to remember compression regardless of dressing, can significantly decrease the amount of drainage, Gambol said.

Seropurulent drainage is a complex bodily fluid that serves as an indicator of infection or inflammation. By understanding its characteristics and potential causes, wound care clinicians can effectively diagnose and treat various conditions, ensuring patients receive appropriate care without complications.