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Convex Ostomy Skin Barriers

Convex Ostomy Skin Barriers

Convex ostomy skin barriers (also known as wafers, baseplates or flanges) are so-called because of the way the flange part of the system adheres to the peristomal skin area.

In this case, the flange protrudes towards the skin which gives it a ‘convex’ appearance and hence the name. These products are not meant for every patient but only for those with certain stoma types. They are used under the direction of a doctor or a stoma nurse. Routine use without prescription from these professionals can lead to the long-term stoma or peristomal area complications.

“One of the guiding principles of ostomy care is to establish and maintain a secure and predictable seal. Products that incorporate convexity are often considered an important tool for achieving this goal. Convexity is defined as A curvature on the skin side of the barrier or accessory. Convex products are frequently cited as the preferred means to manage flat or retracted stomas and to compensate for irregular peristomal planes such as creases or folds. Although a variety of convex products are available with different depths and shapes, there is little supporting evidence to guide their selection and use.

The origins of convex product development are not known. Limitations in early ostomy product availability and the need to cope with poorly constructed stomas or irregular body contours were historically addressed by creative use of pastes, belts, rings, and medical adhesives. During the 1980s and early 1990s, multiple ostomy product manufacturers designed and released firm convex skin barriers designed for both 1- and 2-piece pouching systems. More recently, manufacturers have introduced additional accessories with convex features such as barrier rings and soft convex skin barriers.

Although the terms ‘convex’ and ‘convexity’ are consistently used to describe the curvature on the adhesive side of the skin barrier or accessory, other descriptors remain undefined. There are no industry standards for the depth, profile, tension, firmness, softness, and flexibility of products with a convex feature.”1

Patients who think they can benefit from using convex ostomy products should consult their ostomy nurse, who will do a physical stoma and abdominal examination. The nurse will be interested in the physical appearance of the stoma, if any scars, the condition of the peristomal skin, and the influence of abdominal folds and contours, if any.  It is only after such an examination that the health professional will be able to advise the patient accordingly.

How Convex Ostomy Skin Barriers work

The protruding peristomal convex curvature forces the stoma out. The curvature also creates a more secure adhesive that conforms to the peristomal skin. This mechanism offers superior results in the management of complicated stoma than the standard flat barriers would give.

Convex Ostomy wafers can be part of:

  • One-piece ostomy systems: the ostomy pouch and the flange cannot be separated.
  • Two-piece ostomy systems: the flange and the pouch are separable. This way, you may change the pouches without needing to remove the skin barrier.

Classification of convex barriers according to the type

  • Fixed convex flange. These are molded and strengthened flanges. Their design makes them ideal for many stoma issues. This type can further be divided into the deep or moderate convexity depending on the degree of the protrusion.
  • Non-fixed convex flanges. These are made with plastic rings, which are fixed to standard flat flanges. The attachment creates a convex appearance, which is usually not as deep as in fixed convex flanges. However, non-fixed convex flanges tend to be soft and more malleable, adapting to the body’s contours easily.

A combination of these types of convex flanges and their respective ostomy systems represent a wide variety of products for the caregiver and the patient to choose from.

Indications for ostomy convex products

In general, convex products are used in cases where a flat flange would not be effective in preventing stomal discharge and leakage. Six common situations include:

  1. Flat or introverted stomas
  2. Post loop-ostomy surgery. This type of stoma is almost always retracted
  3. Wrinkled peristomal skin
  4. Irregular surgical scars
  5. A Telescoping stoma. These are stomas that protrude when the patient is upright but retract when reclining.
  6. Flabby uneven abdomen

Importance of the use of ostomy convex products

“Ostomy surgery results in a dramatic alteration in elimination processes and body image – changes that impact both the patient and family. Peristomal skin complications further magnify this alteration, negatively affecting patient adjustment. For the healthcare system, peristomal skin complications usually mean resource utilization – increased patient care needs and the struggle to attain an optimal functional status or comfortable state of well-being are expensive. When addressing prevention and treatment, an outcomes measurement plan that tracks and documents 1) clinical effectiveness of the intervention; 2) impact on functional status and well being, 3) satisfaction with care provided, and 4) cost should be considered. Measuring outcomes documents intervention effectiveness and demonstrates the value of services.

As in most situations, treatment is more expensive than prevention. Additional patient visits, equipment expenses, embarrassment about leakage and odor problems, plus lost work days and altered social activities, are costs that could be avoided or significantly decreased with routine surveillance.

The skin plays an important role in ostomy care, providing the surface on which the pouching system is adhered. Intact, dry epidermis and a well-fitted pouching system enable a sustained, predictable wear time. When skin integrity is compromised or when drains or an open incision infringe on adhesives, potential for pouch leakage exists. The cyclical pattern of pouch leakage/skin erosion/pouch leakage must be broken to enable epidermal resurfacing and restoration of an intact seal. Peristomal skin protection is the cornerstone of ostomy management; treatment of the skin relies on methods to create dry surfaces, fill irregular contours, and treat infections, while an adhesive seal is maintained.”2

Complications associated with using Convex Ostomy Skin Barriers

“Every year thousands of people undergo surgical procedures for diversion resulting in an intestinal or urological stoma. Advances in ostomy equipment/pouches and wound care options, as well as access to wound ostomy continence (WOC) nursing expertise have led to better outcomes for this patient population. However, this progress has been hindered by today’s shorter hospital stays and laparoscopic procedures, which result in less time for patients to learn ostomy basics and measures to prevent skin complications. The surgeon’s goal is a well-constructed stoma. Unfortunately, this goal is not always achieved, as 10 to 70% of ostomy patients experience some type of peristomal skin problems. Many of these issues can be prevented when an enterostomal therapy (ET) or WOC nurse is an integral part of patients’ preoperative and postoperative care. However, as some colorectal surgeons and consequently their patients do not have access to a WOC nurse, it is important for the surgeon be able to identify and manage any peristomal complications that may occur.

Thousands of patients suffer from some type of peristomal skin disturbance at some point while living with an ostomy whether temporary or permanent. There are mechanical, chemical, microbial culprits to these skin complications. These dermatological conditions can range from an abrasion or skin stripping to the more complex, pyoderma gangrenosum.”3

The main mechanism of convex ostomy products is persistent pressure on the area around the stoma. This pressure can cause problems in the peristomal skin, including:

  • Skin irritation, redness and pain. “Contact dermatitis occurs in stoma patients as a response of the skin to contact with external agents. The etiology may be either an irritant or an allergic reaction. Irritant contact dermatitis -the most common type- is caused by mechanical injury to the skin from pouch removal, contact of the skin with stoma effluent, or irritation from solvents, cements or other products acting alone or in combination. Treatment of irritant contact dermatitis should include removal of the irritant chemicals, pouch refitting, and often patient education. Peristomal skin medications are usually not necessary, since the problem should resolve when the underlying cause has been removed. If the skin is erythematous and moist, applying the Stanley procedure will help to absorb moisture and provide an intact surface for adhesion of the appliance. This involves the application of three layers of a skin-barrier powder / and alcohol-free skin prep onto any denuded peristomal skin. Each layer is allowed to completely dry between applications.
    Allergic contact dermatitis is an allergic reaction to a specific stomal product. Because allergic contact dermatitis is relatively rare, it is important to search for an irritant cause first. If the condition is considered to be allergic, then patch testing should be performed to identify the causative agent and to confirm that the reaction is allergic. It is important not to attribute what might be a simple irritant contact dermatitis to an allergic reaction, since this restricts the patient’s ability to use thee adhesive material that has been implicated in the allergic reaction, even though the material may otherwise have been useful for the patient.”4
  • Skin lacerations, stoma injury and bleeding.
    “Stoma trauma or lacerations is an injury or cut on the stoma mucosa. This can occur when the appliance opening is too small or is improperly placed over the stoma, with shaving, or as a result of direct in jury to the stoma. A laceration appears as a yellow to white linear discoloration in the mucosa where the injury occurred. Bleeding may occur at the site and there may be blood in the pouch. No pain is evident as there are no nerve endings in the mucosal layer of the bowel. Management of a stoma laceration is to identify and correct the cause. The appliance should be altered to fit the stoma appropriately. If the stoma mucosa is bleeding significantly at the time of appliance change, direct pressure should be applied to the site until bleeding is controlled.”5
  • Infection and gangrene formation. “Gangrene is a term that describes dead or dying body tissue(s) that occur because the local blood supply to the tissue is either lost or is inadequate to keep the tissue alive. Gangrene has been recognized as a localized area of tissue death since ancient times.  The Greeks used the term gangraina to describe putrefaction (death) of tissue. Although many laypeople associate the term gangrene with a bacterial infection, the medical use of the term includes any cause that compromises the blood supply that results in tissue death. Consequently, a person can be diagnosed with gangrene but does not have to be ‘infected.’  There are two major types of gangrene, referred to as dry and wet. Many cases of dry gangrene are not infected. All cases of wet gangrene are considered to be infected, almost always by bacteria.”6
  • Peristomal hernia. “Peristomal hernia is an incisional hernia that develops at the site of a colostomy or ileostomy, and is among the more common complications of intestinal stomas. The hernia sac usually lies within the attenuated layers of the abdominal wall, but in some instances may tract subcutaneously adjacent to the stoma. Like many stomal complications, formation of a hernia often results from one or more technical errors, which underscores the importance of proper preoperative planning and close attention to detail in the operating room. Other factors that may contribute to the development of peristomal hernias include obesity, advanced age, malignancy, malnutrition, steroid use, and increased abdominal pressure from ascites, chronic pulmonary disease, or obstructive uropathy.”7

“Peristomal skin complications have many implications for the patients and the care givers assisting them. Ranging from mild erythema to deep, full thickness ulceration, from contact dermatitis to PPG, peristomal skin complications have a wide range of causes, treatments and effects on our society as a whole. Preventative measures are often just as important as the wound care treatments themselves, and the best way to ensure that complications are avoided is to partner with qualified and experienced health care providers for preoperative as well as postoperative care. Specially trained ostomy nurses may assist patients by not only treating complications of the stoma, but just as importantly by helping the patients take good care of their stoma, and maintain a good fit of the products they use.

With proper prevention and care, the quality of life of patients with stomas can be high. Anxiety, financial considerations, and disability can be assuaged with proper care and teamwork between medical staff, patient, and family.”8

To improve the efficiency of convex ostomy skin barriers, accessories such as ostomy belts can be used. These belts assist holding the convex flange more securely to the peristomal skin area.

As with standard flanges, convex types are manufactured as pre-cut or cut-to-fit and their use should be determined after consulting with your health care provider.


(1) Alvey, B., & Beck, D. E. (2008). Peristomal dermatology. Clinics in colon and rectal surgery, 21(01), 041-044. Available online at

(2) Hoeflok, J., Salvadalena, G., Pridham, S., Droste, W., McNichol, L., & Gray, M. (2017). Use of convexity in ostomy care: Results of an International Consensus Meeting. Journal of Wound, Ostomy, and Continence Nursing, 44(1), 55. Available online at

(3) Rolstad, B. S., & Erwin-Toth, P. L. (2004). Peristomal skin complications: prevention and management. Ostomy Wound Management, 50(9), 68-77. Available online at

(4) Gordon, P. H., & Nivatvongs, S. (2007). Principles and practice of surgery for the colon, rectum, and anus. CRC Press. Available online at

(5) Fischer, J. E., Bland, K. I., & Callery, M. P. (Eds.). (2006). Mastery of surgery. Lippincott Williams & Wilkins. Available online at

(6) Zulfekar, A., Shirin, S. (2012). Gangrene. Technical Report. Available online at

(7) Pearl, R. K., & Sone, J. H. (2002). Management of peristomal hernia: techniques of repair. Nyhus and Condon‘s Hernia, 5th edn. Lippincott Williams & Wilkins, Philadelphia, 415-422. Available online at

(8) Doctor, K., & Colibaseanu, D. T. (2017). Peristomal skin complications: causes, effects, and treatments. Chronic Wound Care Manage Res, 4, 1-6. Available online at

María Laura Márquez
13 October, 2018

Written by

María Laura Márquez, general doctor graduated from The University of Oriente in 2018, Venezuela. My interests in the world of medicine and science, are focused on surgery and its breakthroughs. Nowadays I practice my more:

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