Dialysis Modality Basics: Haemodialysis vs Peritoneal Dialysis

Haemodialysis (HD) is the most common form of dialysis worldwide. It works by drawing your blood out of the body through a vascular access point, passing it through an external filter called a dialyser, and returning the cleaned blood to your circulation. The dialyser contains thousands of tiny hollow fibres that act as a semi-permeable membrane, allowing waste products like urea and creatinine, along with excess fluid, to pass through while keeping essential blood cells and proteins in place.

A standard in-centre haemodialysis session lasts between three and a half to five hours and is typically scheduled three times per week — usually on a Monday-Wednesday-Friday or Tuesday-Thursday-Saturday pattern. During each session, a nurse or technician monitors your blood pressure, fluid removal rate, and overall well-being. The dialysis machine controls the speed of blood flow, the composition of the dialysis fluid, and how much fluid is removed during the session.

For haemodialysis to work, you need a reliable vascular access. The preferred option is an arteriovenous (AV) fistula, which is created surgically by connecting an artery to a vein in your arm. This causes the vein to grow larger and stronger, making it suitable for repeated needle access. An AV fistula typically needs to be created three to six months before you start dialysis so it has time to mature. Alternatives include an AV graft (a synthetic tube connecting artery and vein) and a central venous catheter, though these carry higher risks of infection and clotting.

Home haemodialysis is an increasingly available option that allows you to dialyse in your own home after completing a training programme. Home HD can be done on a conventional three-times-per-week schedule or more frequently — some patients do shorter daily sessions or longer overnight sessions. Research suggests that more frequent or longer haemodialysis sessions can improve blood pressure control, reduce the need for medications, and improve overall well-being.

Peritoneal dialysis (PD) takes a fundamentally different approach to filtering your blood. Instead of using an external machine with a synthetic filter, PD uses a membrane that is already inside your body — the peritoneum. This thin layer of tissue lines your abdominal cavity and, like the dialyser membrane in HD, it is semi-permeable, meaning it allows waste products and excess fluid to pass through while retaining blood cells and essential proteins.

During peritoneal dialysis, a sterile cleansing solution called dialysate is introduced into your abdominal cavity through a soft, flexible catheter that is surgically placed through your abdominal wall. The catheter is permanent and remains in place for as long as you are on PD. Once the dialysate is inside your abdomen, it draws waste products and extra fluid across the peritoneal membrane through a process called osmosis and diffusion. After a set dwell time — the period during which the solution remains in your abdomen — the used dialysate is drained out and replaced with fresh solution.

There are two main types of peritoneal dialysis. Continuous ambulatory peritoneal dialysis (CAPD) involves performing manual exchanges throughout the day, typically three to four times, with each exchange taking about 30 to 40 minutes. Automated peritoneal dialysis (APD) uses a machine called a cycler that performs multiple exchanges automatically while you sleep, usually over 8 to 10 hours overnight. Some patients use a combination of both approaches.

PD is almost always performed at home, giving you far more control over your treatment schedule. Most patients complete a training programme of one to two weeks with a specialist PD nurse before starting treatment independently. The training covers how to perform exchanges, maintain sterility, recognise signs of infection, and troubleshoot common problems.

While both haemodialysis and peritoneal dialysis achieve the same fundamental goal — removing waste and excess fluid from your body — they differ significantly in how they fit into your daily life. Understanding these practical differences is often more helpful than comparing clinical outcomes, because both modalities are effective treatments and survival rates are broadly similar in the first several years.

The sections below break down the most important areas of difference to help you think through which modality might suit you best. Keep in mind that everyone's situation is unique, and what matters most to one person may be less important to another.

One of the most noticeable differences between HD and PD is how they structure your time. In-centre haemodialysis requires you to be at a dialysis unit for approximately four hours, three times per week. When you factor in travel time, check-in, needle insertion, and post-treatment recovery, a dialysis day can easily consume five to six hours or more. Many patients describe HD days as largely "lost" to treatment, particularly if they experience fatigue or low blood pressure after sessions.

Peritoneal dialysis, by contrast, is done every day but tends to integrate more naturally into your routine. If you are on APD, the cycler runs overnight while you sleep, meaning your daytime hours remain largely free. CAPD exchanges take around 30 to 40 minutes each and are spread throughout the day — you might do one in the morning, one at lunchtime, one in the late afternoon, and one before bed. While this means you are never fully "off" from dialysis, many PD patients find that the treatment fits around their existing schedule rather than dictating it.

Home haemodialysis offers a middle ground. If you are trained to dialyse at home, you may have more flexibility in choosing when to do your sessions. Some home HD patients do shorter, more frequent sessions (such as two to three hours, five to six times per week), which can reduce the dramatic fluid shifts and post-treatment fatigue associated with conventional three-times-per-week HD.

Centre-based haemodialysis means travelling to a hospital or standalone dialysis unit for every session. For some patients, this is reassuring — you are surrounded by trained staff, and any problems during treatment can be addressed immediately. The social aspect can also be positive; many patients form friendships with others at the unit. However, the need to travel regularly can be a significant burden, especially if you live in a rural area or have limited transport options.

Peritoneal dialysis is done at home, which many patients find liberating. You avoid the regular commute to a dialysis centre, and you can create a comfortable treatment environment in your own space. However, home-based treatment does require a dedicated, clean area for performing exchanges and storing supplies. PD supplies — boxes of dialysate bags and associated equipment — take up meaningful storage space, and deliveries are typically made monthly. You will need a clean, dry area to store these supplies and a well-lit, draught-free space for performing your exchanges.

Your home situation matters more than you might initially think. If you live in a small flat with limited storage, the practicalities of PD supply storage may be challenging. Conversely, if you live a long distance from a dialysis centre, PD may be far more convenient than making three trips per week for HD. These logistical factors are worth considering alongside the medical aspects of each modality.

Peritoneal dialysis generally offers more day-to-day independence. You manage your own treatment, set your own schedule (within clinical guidelines), and do not rely on a dialysis centre's timetable. This sense of control can be psychologically valuable — many PD patients report feeling more like an active participant in their care rather than a passive recipient of treatment.

With centre-based haemodialysis, the clinical team handles most aspects of your treatment. You turn up, are connected to the machine, and the nurses manage the session. Some patients find this comforting — they do not want the responsibility of managing their own dialysis, and they prefer to have trained professionals overseeing every treatment. This can be especially relevant for older patients or those who feel anxious about self-managing a medical treatment.

Home haemodialysis, like PD, offers greater independence, though it requires a more intensive training programme and, in many cases, a care partner who can be present during sessions in case of emergencies. The level of independence you want — and feel comfortable with — is an important factor in your decision.

It is worth noting that independence in PD comes with responsibility. You need to be diligent about hygiene, consistent with your exchange schedule, and attentive to any signs of infection or complications. If the idea of taking this level of ownership over your treatment feels empowering, PD may be a strong fit. If it feels burdensome, centre-based HD may be more appropriate.

Dietary restrictions are a reality of life on dialysis, but they differ between HD and PD. Haemodialysis patients typically have stricter limits on fluid intake because fluid accumulates between sessions (which are two or three days apart). Potassium and phosphorus restrictions are also common, as these minerals build up when the kidneys are not functioning and are only removed during dialysis sessions.

Peritoneal dialysis patients often have a more relaxed fluid allowance because PD is performed daily, providing more continuous fluid removal. Potassium restrictions may also be less strict on PD for some patients. However, PD introduces a dietary consideration that HD patients do not face: the dialysate solution contains glucose (sugar), and a significant amount of this glucose is absorbed through the peritoneum during each exchange. This extra calorie load can lead to weight gain, elevated blood sugar, and raised triglyceride levels. PD patients are generally advised to be mindful of their overall calorie and carbohydrate intake to offset the glucose absorbed from the dialysate.

Protein needs are actually higher on PD than on HD, because protein is lost through the peritoneal membrane during each exchange. Your renal dietitian will help you develop a meal plan that accounts for these specific nutritional requirements. Both modalities require ongoing attention to diet, but the particular focus areas differ.

Travel is possible on both modalities, but the logistics differ considerably. If you are on centre-based haemodialysis, travelling requires arranging dialysis sessions at a unit near your destination. This is called "holiday dialysis" in the UK, and while many centres accommodate visiting patients, it requires advance planning — sometimes weeks or months in advance, depending on availability. International travel adds further complexity, including potential costs if treatment abroad is not covered by your health system.

Peritoneal dialysis tends to be more travel-friendly. Your dialysate supplier can usually arrange deliveries to your destination within the UK, and for international travel, many suppliers have networks that can ship supplies overseas. You carry your treatment with you in a sense — all you need is a clean space to perform your exchanges. APD patients do need to travel with their cycler machine, which is portable but adds to your luggage. CAPD patients only need their bags and connection equipment, which is lighter and more compact.

Home haemodialysis patients may also find travel challenging, as they cannot easily transport their dialysis machine. Most home HD patients revert to centre-based dialysis when travelling, which requires the same advance arrangements as any centre-based HD patient would need.

Your medical history and current health status can influence which modality is most appropriate. While many patients have a genuine choice, certain conditions may favour one option over the other. Your nephrologist will assess these factors as part of the shared decision-making process.

Haemodialysis may be preferred if you have had extensive abdominal surgery, abdominal hernias, or inflammatory bowel disease, as these conditions can compromise the peritoneal membrane or make catheter placement difficult. Patients with very limited residual kidney function may also achieve better clearance on HD, as the treatment is more intensive per session. Additionally, if you have significant vision or dexterity problems that make it difficult to manage the sterile connection process, centre-based HD — where the clinical team handles the technical aspects — may be safer.

Peritoneal dialysis may be preferred if you have significant cardiovascular instability, as PD provides gentler, more continuous fluid removal without the dramatic blood pressure swings that can occur during HD sessions. PD is often favoured for patients who wish to preserve their remaining kidney function for as long as possible, as research suggests that residual kidney function may decline more slowly on PD than on HD in the first few years. PD is also generally preferred for young children and may be chosen for patients who have poor vascular access options.

Neither modality is absolutely contraindicated in most patients. If you have a strong preference for one modality, discuss this openly with your nephrologist — in many cases, clinical concerns can be managed and your preference accommodated. The most important thing is that you are informed and actively involved in the decision.

It is also worth knowing that clinical outcomes for HD and PD are broadly comparable. Large studies have found similar survival rates in the first several years of treatment, though there are differences in specific complications. HD carries risks related to vascular access (infection, clotting, failure) and the haemodynamic stress of intermittent treatment. PD carries risks of peritonitis (infection of the peritoneal cavity) and, over time, changes to the peritoneal membrane that may reduce its effectiveness as a filter.

Choosing between haemodialysis and peritoneal dialysis is a deeply personal decision, and there is no single answer that is right for everyone. The best approach is to think about what matters most to you in your daily life and then consider how each modality aligns with those priorities.

Start by reflecting on a few key questions. How important is maintaining your current work schedule? Do you value independence and self-management, or would you prefer to have a clinical team handle your treatment? What is your home environment like — do you have space for supplies and a clean area for exchanges? How often do you travel, and how important is travel flexibility to you? Do you have a care partner who is willing to support you with home treatment, or are you managing on your own?

Many renal units offer pre-dialysis education programmes where you can learn about both modalities in detail, speak to patients who are on each type, and even visit a dialysis centre and see PD equipment. Take advantage of these opportunities if they are available to you. Hearing from people who are actually living with each modality can be far more informative than reading about them.

Remember that your choice is not necessarily permanent. Many patients switch modalities at some point — sometimes by choice, sometimes because of a change in medical circumstances. Starting on one modality does not lock you in. If you try PD and find it is not working for your lifestyle, you can transfer to HD, and vice versa. Knowing that you have this flexibility can take some of the pressure off the initial decision.

If you are feeling stuck or overwhelmed, it can help to write down your priorities and concerns. Some patients find it useful to create a structured comparison, listing the pros and cons of each modality as they relate to their specific situation. Your renal team — including your nephrologist, specialist nurse, and renal social worker — can help you work through these factors.

Going into your modality discussion with prepared questions can help you make the most of the conversation. Here are some questions that many patients find useful:

• Am I a suitable candidate for both HD and PD? Understanding whether any medical factors limit your options is the essential first step.
• What does the vascular access or catheter placement process involve? Both modalities require a surgical procedure to create access. Ask about the timeline, what to expect, and how long before you can start treatment.
• What is the training process for PD or home HD? If you are considering a home-based modality, understanding the training commitment and ongoing support available is important.
• How will my current medications and health conditions affect my experience on each modality? Your nephrologist can explain how conditions like diabetes, heart disease, or previous surgeries may influence your day-to-day experience on HD versus PD.
• What happens if the modality I choose does not work out? Knowing that switching is an option — and understanding the process — can reduce the anxiety around making a choice.
• What support is available for home-based treatment? Ask about 24-hour helplines, home visits, and how quickly the team can respond if you have a problem outside of normal hours.
• Can I speak to patients who are currently on each modality? Peer support and real-world perspectives are invaluable when making this decision.

Your nephrologist wants you to be an active participant in this decision. Do not be afraid to ask as many questions as you need, take notes, or bring a family member or friend to the appointment for support. This is your treatment and your life — your voice matters most in this conversation.