Introduction

A wound is a breakage in the normal structure of the skin and tissues and can occur due to external injuries or surgery. A small amount of thin, colourless liquid is normal in most wounds (known as exudate) and is essential to the healing process.^1,2 However, if this liquid deviates from this consistency, it may indicate purulent drainage.

Purulent drainage is a type of liquid (pus) that oozes from a wound, which has:³

• A thick texture 
• A “milky“ appearance
• A Yellow, green, white or brown colour – this is due to the presence of white blood cells and bacteria 
• A distinct or unpleasant odour 

Purulent drainage is often a sign of wound infection. Purulent drainage will often increase as an infection worsens. Infection can interfere with the healing process and cause further complications if left untreated. Earlier identification with earlier and appropriate treatment can help speed up healing and prevent complications.^1-4,6 

Other symptoms of an infected wound can include:^1-4,6 

• Skin discoloration e.g. redness
• Oedema (swelling) 
• Warmth
• Increase in pain
• Fever
• Chills
• Nausea and/or vomiting 
• Non-healing wound 

Causes

During the early stages of healing, wound drainage is a result of the blood vessels dilating to allow tissue to repair and recover. However, when drainage becomes purulent, it is often due to wound infection. Infected wounds can be caused by bacteria.

Our skin contains bacteria (normal flora) which are normally harmless if the skin is unbroken. However, open skin or tissues either through injury or surgery can allow entry and growth of bacteria in the wound, which can then spread further. The most common types of bacteria that cause wound infection in patients include:⁵

• Staphylococcus aureus (the most common natural skin flora)
• Methicillin-resistant Staphylococcus aureus (MRSA)
• Escherichia coli (E. coli) 
• pseudomonas aeruginosa 
• Streptococcus

Infection of the wound can make the healing process longer and if left untreated can cause further complications. Pus is a product of the body's natural defence mechanism against infection, where the white blood cells aim to destroy the bacteria. As a result, white blood cells, bacteria and liquefied tissue debris accumulate at the site of infection and collectively appear as purulent drainage. Wound infection may become chronic (lasting more than 8 weeks), which can prolong the healing stage to as much as several months. This can cause further pain, discomfort and psychological distress.^2,8 

Contributing factors 

Anyone is susceptible to purulent drainage, but various factors can pose a greater risk of wound infections and slower wound healing.^2,6

The risk of wound infection can increase due to:

• Poor wound dressing 
• Poor hand hygiene 
• Unhygienic environmental conditions e.g., dust, mold, unclean surfaces 
• Open wounds Large, jagged edges or deep wound 
• The wound was caused by a contaminated or foreign object 
• The wound was caused by a bite from organisms like insects or animals 

Certain health conditions and/or medications can also increase the risk of infection:

• Advancing age 
• Obesity 
• Repeated trauma 
• Type 1 or 2 diabetes
• Weakened immune system e.g., HIV/AIDs, cancer, or immunosuppressant medications 
• Poor blood circulation e.g., anaemia, heart diseases, lung diseases, kidney impairment, rheumatoid arthritis 
• Lack of mobility or immobility e.g., paralysis or bed-bound 
• Malnutrition 
• Inappropriate antibiotic use e.g. prescribed when not needed, wrong antibiotic prescribed etc
• On radiation therapy or chemotherapy 
• Had previous surgery 
• Excessive alcohol use
• Excessive smoking
• Drug abuse

Complications 

Infections are the most common complication of untreated purulent drainage, which can worsen and have the potential to spread to other parts of the body if left untreated. Further serious complications may include:^2-6

• Tetanus (a.k.a lockjaw)
• Cellulitis – a bacterial infection of deeper layers of the skin. This can cause redness, swelling, nausea, dizziness, fever, vomiting and pain 
• Osteomyelitis – a bacterial infection of the bone or bone marrow. This can cause redness, pain, swelling, tiredness and fever
• Necrotising infection – although rare, it is a bacterial infection that can lead to widespread tissue loss throughout the body. This requires urgent medical treatment 
• Septicaemia – bacteria in the blood, also known as blood poisoning or sepsis. It can be life-threatening and requires urgent medical treatment 

Treatment and management 

Recognising early signs of purulent drainage and wound infection can aid in effective diagnosis and treatment. Effective treatment should consider a holistic assessment of you as an individual, the type of wound, the site of the wound and the wound care environment.

Treatment of purulent drainage and wound infection can vary depending on several factors including the site, severity and if you have any other underlying health conditions. Regular monitoring of the progress of healing is needed so treatment plans can be readjusted as necessary.^2,6,8-10

Treatment may include the following: 

Wound care

Your healthcare provider may help and advise on how to keep the wound clean, with proper precautions e.g., hand washing before dressing the wound, antiseptic fluid and clean dressing. Keep your dressing dry and clean, and replace it if it becomes damp or dirty. Do note if your dressing is unintentionally soaked several times a day, it indicates that you are experiencing abnormal wound drainage. Seek a healthcare provider immediately to prevent further complications.

Antibiotics and medications 

Your healthcare provider may prescribe you with antibiotics and/or pain relief. If you are already on antibiotics or any other medication, it would be worth reviewing with your healthcare provider. For severe or deeper infections, intravenous antibiotics may be considered. For individuals with a life-threatening infection (e.g. sepsis), urgent hospital admission with a higher level of monitoring will be required.

Drainage procedures

Some cases of bacterial infections resolve with topical antibiotics. However, in other cases where there is a localised collection of pus (an abscess), an incision and drainage may be recommended. This option may be done if:

• The abscess is larger, where drainage of the pus would help promote healing
• The abscess is associated with symptoms like fever or chills
• The abscess persists despite antibiotic treatment
• It is required to prevent the spread of infection 
• The abscess is in certain body parts such as joints, to prevent further complications 
• You have other underlying conditions like being immunocompromised, as drainage will prevent more severe infections 

Surgical interventions 

In severe cases, surgical procedures may be required to remove the infected tissues or address the source of infection. 

Prevention 

There are several things you can do to minimise the risk of purulent drainage and wound infection, such as:^8-10

• Maintaining good personal hygiene 
• Proper wound care
• Appropriate medication e.g. antibiotic use as advised by your healthcare provider
• Maintaining and monitoring any underlying conditions e.g. well-controlled diabetes 
• Maintaining a healthy lifestyle with balanced nutrition, regular exercise, and adequate rest 
• Proper monitoring of your healing progress 

FAQs

How long does it take for a wound to heal?

Generally minor wounds heal in days, while larger or surgical wounds may take weeks to months. However, there are various factors that can affect healing time, such as wound type, size and individual health. For example, individuals with poor blood supply, obesity, malnutrition etc., are more likely to have a poorer rate of wound healing.

What is purulent drainage?

Purulent drainage is the presence of pus, a thick “milky” fluid. This pus consists of a mixture of bacteria, dead white blood cells and tissue debris. It is often a sign of infected wounds.

What causes purulent drainage in wounds?

Purulent drainage is typically caused by bacterial infections in wounds. This results in an immune response that produces pus as the body attempts to combat the infection. 

What are the signs of wound infection?

Signs of wound infection can include increased swelling, redness, pain, warmth, and the presence of pus or a foul odour. Fever and systemic symptoms may also indicate infection.

How is purulent drainage treated?

Treatment for purulent drainage can vary depending on individual needs, the type of wound, the site of the wound and if the individual has any underlying health conditions. Generally, treatment involves antibiotics, proper wound cleaning, and drainage if necessary. 

When is drainage of an abscess necessary?

Healthcare professionals assess the need based on specific criteria. Drainage is considered when an abscess is large, persistent, is associated with symptoms in other parts of the body, or is located in critical areas.

How can I prevent purulent drainage in wounds?

Preventive measures include maintaining wound hygiene and care, infection control, appropriate antibiotic use, and addressing any risk factors.

What promotes wound healing?

Various lifestyle factors can support optimal wound healing, such as proper wound care, a balanced diet, maintaining good general health, and avoiding excessive smoking and alcohol intake. 

When should I seek medical attention for a wound?

Seek your healthcare provider promptly if you notice any worsening signs and symptoms like pain, fever, and signs of infection or prolonged healing. Receiving early and effective treatment will help prevent any complications.

Summary

There are various types of fluid drainage throughout the healing process of a wound. Purulent drainage is a type of liquid which has a thick texture and a “milky” appearance, which can be yellow, green, white, or brown in colour and may also present with a distinct odour. Purulent drainage is an indication of wound infection and poor wound healing.

It is important to monitor your wound healing. Seek advice from your healthcare provider promptly if you notice signs of purulent drainage or have any questions or concerns. Early and appropriate treatment allows wounds to heal safely, preventing more serious health complications.