What Is Serous Drainage

  • Talita Utomo BSc Biomedical Science, University of Sheffield

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Serous drainage: A comprehensive guide to the watery fluid of healing

Meet serous drainage, the unsung hero in our bodies. This unassuming, clear fluid quietly aids in healing, preventing inflammation, and alerts us if any harmful microorganism is slowly invading our bodies. In this guide, we'll uncover its hidden importance and appreciate the vital role serous drainage plays in keeping us healthy!


Serous fluid or drainage is a clear, watery, and pale-yellowish bodily fluid that is commonly found in various parts of the body. It is a type of exudate, which is a fluid that leaks out of blood vessels and into nearby tissues.1 A small amount of serous drainage is expected to leak out of a newly forming scab or wound. Still, a larger amount of this fluid could be an indicator of an increased population of harmful microorganisms living and growing, potentially indicating an infection.

Understanding serous drainage is very important as it holds diagnostic value, helping in the identification of wound healing stages and early detection of potential complications. Effective management of serous drainage is essential for wound care, as neglecting it can lead to infections and delayed healing. This understanding is crucial for patients, as it reduces pain and promotes faster recovery. This article will briefly explain what serous drainage is, if you should be worried if you see this exudate out of your healing wounds, and how to manage it.

The nature of serous fluid

Serous fluid is primarily made of water, electrolytes (such as sodium and chloride), and small amounts of proteins, including albumin. It is generally thin, transparent, and slightly thicker than water. Serous fluid can be found in several parts of the body, including the pleural cavity (between the layers of the pleura surrounding the lungs), pericardial cavity (around the heart), and peritoneal cavity (in the abdominal area).4 These cavities are lined with serous membranes that secrete and contain serous fluid. The serous fluid constantly lubricates the pleural surface throughout lung inflation and deflation, facilitating effortless sliding over each other. Serous drainage also keeps the organs from sticking to one another when they are moving by acting as a cushion and barrier. Additionally, surface tension produced by the serous fluid draws the two pleura in the lungs together. 5 While its primary function is to act as a lubricant, serous fluid also gives the cells of serous membranes nutrition and oxygen. 

Serous drainage in wounds & surgical sites

Many diseases can cause serious leakage, which is frequently the body's response to an infection or inflammation. Pleural effusion is a lung illness caused by pneumonia that can cause serous fluid to build up in the pleural cavity. Similarly, serous drainage can increase due to heart failure, leading to fluid accumulation in the lungs and other bodily cavities. This serous fluid could be a great tool to diagnose the severity of pleural effusions.6 When the peritoneum lining the abdominal cavity becomes inflamed, a condition known as peritonitis, the body may respond by producing serous fluid. Serous drainage can also be produced in the digestive system as a result of inflammation brought on by inflammatory bowel illnesses, including Crohn's disease and ulcerative colitis.7

Additionally, serous drainage is essential in surgical and wound-healing conditions. As part of the body's natural healing process, serous leakage is frequently observed in post-operative wound care.8 Serous fluid production is also a common occurrence in burn patients as their bodies try to repair injured tissues. When the body heals from tissue trauma following orthopaedic surgeries, serous drainage may also occur, requiring careful observation and attention.9 

Clinical significance

Despite being usually clear and odourless, serous fluid can be an important diagnostic tool for determining infections or consequences. Anything different from its typical traits may be seen as a warning and have diagnostic value. Pus in the fluid and increased viscosity are changes that might indicate an infection or other problems. Another indicator is a significant increase in serous discharge. Moreover, when such issues exist, serous drainage changes frequently correspond with symptoms such as fever, chills, and fatigue. If you experience these complications, do visit a healthcare provider. 

Management and care

It is of the utmost importance to follow recommended procedures for wound care and surgical sites regarding serous drainage control. Strict guidelines, checks, and delicate cleaning methods must be followed. It is crucial to choose the suitable dressings carefully and change them as directed by your healthcare practitioner to properly control serous discharge. Sterile saline irrigation of wounds may also promote the elimination of contaminants and encourage healing. Careful application of antibiotics in conjunction with good nutrition is essential to prevent infection and promote recovery. Necessary acts that patients are recommended to take include enough hydration, proper pain management, and learning about the early indicators of complications. Patients are also frequently urged to stop smoking and strengthen their immune systems.10

In some operations, surgical drains are also utilised to remove extra serous fluid. Surgeons will install these drains when surgical operations or large wounds cause a considerable accumulation of serous fluid.  To reduce the risk of infection, healthcare practitioners must ensure that these drains are fitted properly and kept in good condition. It is essential to regularly evaluate serous fluid production since it offers significant insights into the healing process and any potential problems.11 While aiming to make the patient as comfortable as possible, the choice of drain type and procedure should be in accordance with the individual patient's requirements as well as the nature of the procedure or wound. By combining these actions, healthcare practitioners may effectively handle serous drainage, reduce the likelihood of infection, and facilitate maximum recovery. 


Serous drainage, often overshadowed by more conspicuous bodily fluids, is a clear and watery substance that plays a critical role in healing and protection within our bodies. Its primary functions include lubricating serous membranes, preventing tissue adhesion, and nourishing these vital structures. Changes in serous drainage characteristics, such as pus in the fluid or increased volume, can serve as indicators of infections or complications, making it a valuable diagnostic tool. In medical contexts, it is encountered in common conditions like pneumonia, heart failure, peritonitis, and inflammatory bowel diseases. In surgical and wound healing scenarios, serous drainage management is essential to prevent infection and support the recovery process, often involving the use of surgical drains. By recognising changes in serous fluid characteristics, healthcare professionals can promptly diagnose and address complications, ultimately ensuring better patient outcomes. Proper wound care and management and the strategic use of dressings & surgical drains are critical components in effective serous drainage control. 


What is serous drainage, and what role does it play in wound healing?

Serous drainage is a watery and clear bodily fluid found in bodily cavities and wounds. Serous drainage production is a natural process commonly found in the first stages of the healing process.

What is the function of serous drainage?

Serous drainage is a lubricant that reduces friction between layers of serous membranes. It also acts as a cushion to prevent organs from sticking to each other and provides nutrition and oxygen to cells of serous membranes.

When do I need to see the doctor regarding serous drainage?

When you notice changes in the fluid, such as the presence of pus and increased thickness, if you feel pain and increased amounts of fluid, you should contact your healthcare provider.

How can you actively participate in serious drainage management?

You should follow your healthcare provider’s instructions, regularly clean or disinfect the wound site as per instructions, be hydrated, have a good and nutritious diet, and maintain a healthy lifestyle (such as not smoking and exercising regularly).


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  2. Vowden K, Vowden P. Understanding exudate management and the role of exudate in the healing process. British Journal of Community Nursing [Internet]. 2003 Nov 1 [cited 2023 Oct 26];8(Sup5):S4–13. Available from: https://www.magonlinelibrary.com/doi/epdf/10.12968/bjcn.2003.8.Sup5.12607
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  7. Elliot MS, Todd IP. Primary suture of the perineal wound using constant suction and irrigation, following rectal excision for inflammatory bowel disease. Annals of The Royal College of Surgeons of England [Internet]. 1985 [cited 2023 Oct 26];67(1):6. Available from: https://www-ncbi-nlm-nih-gov.sheffield.idm.oclc.org/pmc/articles/PMC2498226/?page=1
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  9. Rudy HL, Cho W, Oster BA, Morris MT, Schulz J. Treatment of Isolated Serosanguinous Incision Drainage after Thoracolumbar Surgery: Is Surgical Management Always Necessary? Surgical Infections. 2019 Oct 7
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  11. Rajaraman Durai, A. Mownah, Ng PCH. Use of Drains in Surgery: A Review. Journal of perioperative practice [Internet]. 2009 Jun 1 [cited 2023 Oct 26];19(6):180–6. Available from: https://journals-sagepub-com.sheffield.idm.oclc.org/doi/epdf/10.1177/175045890901900603

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Talita Utomo

BSc Biomedical Science, University of Sheffield

Talita is a second-year Biomedical Science student with a passion for science and a commitment to making a meaningful impact. Beyond her professional journey, she has discovered an interest in writing health articles, combining her scientific background with effective communication skills.

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