What is convexity?
What does convexity aim to do?
Instances/problems which convexity can alleviate or work around?
– Instances where convexity is generally not advisable
Considerations when using convex products
– Ostomy Belts & Convexity
– The difference between pre-cut and cut-to-fit products and their impact on convexity
– Stoma Nurse Review During Long Term Use
– Convexity-related problems to look out for during use
I think Convexity might be for me, what should I do next?
Some Convexity Products
Convexity is one of the ostomy world’s buzz words as it’s a well proven, cost effective solution to many of the more common problems associated stoma and peristomal issues. If you have ever had problems managing your stoma, especially with leakage related problems, and sought advice online then no doubt someone will have asked you if you’ve ever tried convexity products.
Whilst the word convexity is often bandied about the many ostomy support forums, groups and mailing lists on the internet the truth is that convexity is only for a quite specific set of conditions and those who can use these special products needs to be determined by a stoma care nurse/WOCN first so as to ensure that the patient’s needs are met and that any problems which can arise from long term convexity wear can be managed accordingly. If a patient were to just start wearing convexity products off their own initiative, and they were in fact not in need of them, or they were being incorrectly applied, or their prolonged wear was not being managed, then they could end up causing more problems than they start with, and even possibly cause damage to their stoma.
In this editorial article we aim to look exactly what convexity is, the different product types out there, as well as examining what its used for and how to correctly use it. We also offer a heads up on the problems that can be associated with convexity wear over a long period of time are, as well as what you should do next if you are curious about trying this style of product.
The majority of ostomy pouch flanges which are available on the market today have a flat adhesive back to them. However, as the name suggests, convex products have a back which protrudes out giving the flange a stepped side-profile appearance. Concavity products, which curve inwards, also exist although they are far less common than their convex brothers. Convex products are available as two piece and one piece products. (If you struggle to remember the difference between concave flanges and convex flanges, then the easier to remember is that concave products curve in towards the pouch – like a cave mouth.)
An example of a convexity flange.The Coloplast Assura with Light Convexity. Note how the centre is raised out.
Speaking purely from a personal standpoint I prefer two piece products for convexity as they are far stronger, offer a longer wear time making them more skin friendly (as I’m not having to remove the pouch once or twice a day) and on the whole I found them to be more effective at their job. However, as I say, that’s just my personal view from my own usage; your opinion might vary wildly from that though.
There are many different convexity products available but most, if not all, revolve around two different types of product; namely Fixed and Non-Fixed.
The Fixed convexity ranges feature products in which the flange itself has been designed, strengthened and moulded into the stepped shape. These give the possibility of a moderate or deep convexity step, and therefore are considered strongest convexity products which can address the largest stoma management problems which can benefit from the use of convex flanges. With the Fixed product steps being moulded and strengthened they are less flexible than traditional flat flanges.
The Non-Fixed range of convexity products are usually based around little plastic rings which clip into existing traditional flat/non-convex product ranges to give them a shallow convex step. These are considered the more gentle convexity product as not only as the step the rings create are less than those in the Fixed ranges, but also because they are softer steps which flex more with the body.
Aside from these two different types of convexity category, there are also three different levels of curvature – shallow, moderate and deep. So when you mix these two areas of convexity product selection together you have a large choice, and a lot of flexibility, over which convex product could be right for you.
Convexity is used to in an aid to giving the appliance a better, longer lasting seal around the stoma by aiming to give a mirror image of the peristomal “plane” – this being the skin around your stoma if it were to be viewed sideways on.
It can also help the stoma to protrude more from the skin by applying pressure around (pushing on) the peristomal skin a bit.
The medical reasons or problems which might benefit from the ostomate using a convexity product are varied, and include – but are not limited to – the following.
Stomas which are flush to the skin, or retracted (pulled inwards)
These stoma types make it difficult for the stool output to be deposited over the flange edge and into the pouch, instead being more likely to just pump be out of the stoma in-between the flange and peristomal skin layers. This is especially problematic for retracted stomas where stoma “seal” products such as Eakins Seals can be difficult to apply effectively.
Most loop ostomies
These stoma types can be prone to stoma retraction.
Any ostomy with a telescoping stoma
This is where the stoma protrudes more during the waking hours. During the patient’s sleeping hours the stoma can become flush to the skin and lead to leakage problems in bed.
This is an example of a retracted stoma.This would benefit from a convex flange.
Wrinkles or creases near the stoma
Creases in the skin near the stoma, be them natural or as a result of surgical after effects, can often prevent flat flanges sticking to them and create a natural cavity behind the flange for the stool to collect in and usually be the most common cause of stoma pouch leakage for that ostomate.
These can also cause similar problems to wrinkles and creases.
Having a stoma in a flabby/flaccid abdomen can cause it to crater. This is where the stoma will sit at the bottom of a hollow in the belly, and it’s incredibly difficult to get a flat flange to stick effectively or with any longevity in these regions.
Your stoma nurse will be able to advise you more fully on whether you should try convexity or not, and all ostomates – regardless of their reasons – should consult a stoma nurse before switching to convexity based products. For more details on why, see section: I think Convexity might be for me, what should I do next?
That said if you have any of the following indicators then you will find the likelihood of the stoma nurse giving you the go ahead to try convexity to be very low. These indicators include – but are not limited to:
A well fashioned stoma
These are “text book” quality stomas which have no real problems as a result of incorrect or problematic surgical creation
If your stoma has a nice spout shape and length to it then it is able to carry your stool output over any problems which convexity may aid with, and deposit the stool into the pouch with little chance of convexity-related leakage problems.
If you have a hernia poking against your peristomal skin then it is not advisable to use convexity based products.
On the whole, the application and wear of a convex flange is no different than that of the standard flat ostomy flange products. However, there are some factors one may need to consider with the use of convexity which would not normally be required during the use of standard flat flanges.
According to a panel held by ostomy products manufacturer Hollister, over 50% of all convexity-wearing ostomates would benefit from, or need to wear an ostomy belt. These belts help maintain an even pressure over the peristomal skin, and for some patients they can be used to enhance the convex effect by applying more pressure than achieved when wearing the flange without a belt. They can also help hold the flange in place on flaccid abdomens, or those ostomates whose stomas are located within a skin fold.
These specially designed belts attach directly to the flange itself, or to the pouch which is in turn attached to the flange. Not all ostomy belts have the same attaching ends, so it’s usually a good idea to use the belt that is manufactured by the same company as your convexity product.
Everyone’s stoma is different. No two are the same. While some ostomates are lucky and have nice rounded stomas, some of us are not so lucky and have sized or shaped stomas.
The irregular stoma ostomates usually use cut-to-fit ostomy flange which will come to them with a pre-defined circular hole cut into it, and then the ostomate will cut out the shape of their stoma into the flange to make it fit better. This is done accurately with the aid of a pre-drawn template, or as time passes by – practise.
However, these cut-to-fit flanges are not necessarily the best first choice for people looking to use convexity. The same Hollister panel which I mentioned earlier has also declared that it is most likely to be more beneficial for the convexity wearing ostomate to use a pre-cut (perfectly round hole) flange and an ostomy seal, rather than using a convexity flange cut to an irregular shape.
The reasons for this are pressure-related. Pre-cut flanges exert the pressure directly onto the immediate peristomal skin in an even manner. Flanges which are cut to an irregular shape may not be exerting the correct pressure to the correct area of your skin.
The panel also concluded that stomas which are significantly smaller than the maximum possible flange aperture will be receiving a vastly reduced convexity effect.
Therefore, because of this, it is advisable to talk to your stoma nurse about which product would be best for you to use with your stoma pre-cut with or without a seal, or cut-to-fit. Unfortunately I cannot really advise you here because – like I said at the start of this section – everyone’s stoma is different and needs evaluating in person by a professional stoma care nurse or equivalent practitioner.
Convexity products are regarded as pressure-related equipment and as such they should really be reviewed at regular intervals by the stoma care nurse –approximately every 6 months once all initial issues are resolved.
The reason for this is because as with any pressure-related device they can cause skin issues such as sores and ulcers. Also, the ostomate can lose or gain weight which can affect the peristomal plane, an alternatively if any herniae were to develop then the convexity would require review again as it will be adding increased pressure to the skin at the point where the herniae is pushing through.
You can also help your stoma nurse, and yourself, by keeping a close eye on your peristomal skin and abdomen whilst using convexity products.
Here is a list of some (but not necessarily all) of the problems and conditions which an ostomate may encounter during long term use of convexity products. These issues would require a follow-up with the Stoma Nurse/WOCN.
If you think you could benefit from wearing a convexity product then your next stop without exception is to contact your stoma nurse, or if you do not have one then a GP would be the logical alternative.
If you’ve read this whole article then you know the reasons for the necessity of you to go to your stoma care nurse, but what will he or she look at to determine if you are suitable for convexity or not?
The meeting will be very much a physical assessment of your stoma and abdomen’s condition. The nurse will check your abdomen to see what folds and creases there are, as well as checking your peristomal plane. The nurse will also assess your stoma, ideally when it is at rest and when its functioning, and check to see if telescopes at all.
Should the nurse consider you suitable for convexity then the second stage of the assessment determines which convexity products you are likely to need and if any extra products are needed such as rings, or ostomy belts etc as we’ve already discussed.
If you were considering enquiring about convexity products, or if after reading this editorial you are wondering if they are right for you then we say “ask your stoma nurse”. You’ve nothing to lose, and everything to gain. Convexity is a very easy-to-use solution and can be used early on in the life of your stoma, so there’s no need to suffer in silence if you are experiencing leakage, or stoma function problems. If convexity is suitable for you then you could possibly overcome your issues with something as simple as a carefully considered change of appliance.
Coloplast Sensura Convex:
ConvaTec Esteem Synergy with Convex-IT
CliniMed/Welland FreeStyle Vie Convex One Piece Closed
Hollister Moderma Flex Convex
Making Sense of Convexity– Hollister Inc.
Convex Flanges – Badgut.org
(Canadian Society of Intestinal Research)
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