Peritoneal dialysis

01Purpose and principlesWhat the treatment does and how it fits into care.

Fresh dialysis solution enters the peritoneal cavity through a permanent catheter, remains for a prescribed dwell and then drains. Urea, creatinine and potassium move down concentration gradients, while glucose or an alternative osmotic agent draws water from the circulation. Small-solute equilibration and water removal change over the dwell, so fill volume, number of exchanges, dwell length and solution strength must be tailored rather than copied between patients.

CAPD provides repeated manual exchanges spread across the day. APD can deliver shorter overnight cycles and a long daytime dwell; it may suit work, sleep and transport needs or particular peritoneal transport characteristics. Neither method is universally superior, and assisted PD can enable treatment when dexterity, vision or physical ability would otherwise be barriers. Home circumstances should be assessed for safe storage and technique without imposing unjustified social exclusions.

The main threats to continued PD are peritonitis, exit-site or tunnel infection, catheter flow failure, leak, hernia, ultrafiltration failure and loss of residual kidney function. Peritonitis can cause sepsis and permanent membrane injury, so every patient needs a written cloudy-bag plan. Long-term review integrates clinical wellbeing, urine and drain volumes, adequacy testing, peritoneal equilibration, nutrition and technique; numbers are interpreted together because satisfactory urea clearance does not correct uncontrolled fluid overload.

Key points

Peritoneal dialysis uses the patient's peritoneal capillaries as the blood compartment and instilled dialysate as the receiving compartment for diffusive solute clearance and osmotic ultrafiltration.
Continuous ambulatory peritoneal dialysis uses manual daytime exchanges; automated peritoneal dialysis uses a programmed cycler, usually overnight, and modality choice should reflect physiology, lifestyle and support.
A clean connection technique, daily exit-site care, a trained patient or assistant and rapid access to the PD team are core safety interventions, not optional extras.
Cloudy effluent is presumed PD peritonitis until confirmed or excluded: contact the PD unit immediately, send effluent cell count and differential, Gram stain and culture, then start the patient’s current centre-approved empirical intraperitoneal regimen after sampling without waiting for laboratory results.
Abdominal pain with clear fluid has a broad differential including constipation, hernia, obstruction, pancreatitis and ischaemia; conversely, some peritonitis episodes have little pain.
Monitor both peritoneal clearance and residual kidney function; preserving urine output can materially improve volume, potassium and overall solute control.
Repeated use of the strongest glucose solutions increases glucose exposure and can damage membrane and metabolic health; optimise salt intake, dwell design, icodextrin and residual diuresis with the PD team.
Icodextrin metabolites can cause falsely high glucose readings with incompatible meters, so only the glucose-monitoring technology approved by the renal service should be used.
Poor drain volume is often mechanical from constipation, catheter migration, kinking or fibrin, but never assume a machine alarm is harmless when pain, leak or infection is present.

02Indications, selection and cautionsWho may benefit, who needs urgent treatment and important alternatives.

Effective exchange

Prescribed fluid flows in without significant pain, dwells for the intended duration and drains near the expected volume with clear appearance.

PD peritonitis

Cloudy effluent, abdominal pain, fever, nausea or diarrhoea raises concern, although immunosuppressed or older people may have subtle systemic signs.

Exit-site infection

Purulent drainage with or without erythema at the catheter exit requires PD-team assessment and can extend along the subcutaneous tunnel.

Mechanical outflow failure

Slow or absent drainage, positional flow and recurrent cycler alarms suggest constipation, catheter displacement, kinking, omental trapping or fibrin.

Ultrafiltration failure

Falling net drain volume with oedema, hypertension or breathlessness may result from membrane transport change, leaks, prescription mismatch or excess salt intake.

Glucose exposure

Weight gain, hyperglycaemia and lipid disturbance can be aggravated by absorption of glucose from dialysate and should influence the broader prescription review.

Red flags requiring action

Cloudy drained fluid needs same-day renal contact even if pain is mild; delay in effluent testing and antimicrobial treatment increases technique failure and sepsis risk.
Hypotension, altered mental state, rising lactate or severe abdominal guarding with suspected peritonitis demands emergency sepsis and surgical differential assessment.
Sudden breathlessness after fill, pleuritic symptoms or a new unilateral effusion can reflect pleuroperitoneal leak and requires the PD team to stop or modify treatment.
Scrotal, abdominal-wall or wound swelling with loss of ultrafiltration suggests a dialysate leak or hernia and should not be managed by progressively larger fill volumes.
A low bedside glucose reading in an icodextrin user should be treated clinically, while any unexpectedly high reading obtained with an unapproved meter must be confirmed urgently by a compatible method.

03Assessment before treatmentTests and checks that guide safe selection.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Peritoneal effluent cell count and differentialFirst step
Why
Confirm inflammatory dialysate and support the diagnosis of PD-associated peritonitis.
Interpretation and limitations
Diagnose PD-associated peritonitis when at least 2 of 3 are present: abdominal pain and/or cloudy effluent; effluent WBC above 100/µL (above 0.1 × 10⁹/L) after a dwell of at least 2 hours with above 50% polymorphonuclear leukocytes; or a positive effluent culture. In rapid-cycle APD, above 50% polymorphonuclear leukocytes strongly supports peritonitis even if the absolute WBC is 100/µL or lower.
02
Effluent Gram stain and culture
Why
Identify the organism and permit targeted intraperitoneal treatment.
Interpretation and limitations
Inoculation into blood-culture bottles improves yield; collect before antibiotics if this does not delay safe empirical treatment and investigate repeated culture-negative episodes.
03
Exit-site and tunnel assessment
Why
Find superficial infection, cuff involvement or a collection that may sustain peritonitis.
Interpretation and limitations
Purulent discharge is more specific than erythema alone; ultrasound can support tunnel assessment when examination is uncertain.
04
Daily exchange and fluid record
Why
Quantify fill, drain, net ultrafiltration, urine, weight and blood pressure trends.
Interpretation and limitations
Falling net removal needs confirmation of prescription delivery, constipation, leaks, membrane function and salt intake rather than reflex high-glucose escalation.
05
Adequacy collection
Why
Measure combined peritoneal and residual urinary small-solute clearance on the centre schedule.
Interpretation and limitations
Collection errors are common; interpret Kt/V or creatinine clearance with symptoms, nutrition, body size and volume state rather than as an isolated pass mark.
06
Peritoneal equilibration test
Why
Characterise solute transport and ultrafiltration to guide dwell length and CAPD or APD design.
Interpretation and limitations
Transport status can change after peritonitis or over time, and the result guides prescription mechanics rather than labelling the person as a treatment success or failure.
07
Abdominal imaging
Why
Assess catheter position, constipation, obstruction, leak, hernia or surgical pathology when clinically indicated.
Interpretation and limitations
A plain radiograph may show migration and faecal loading; CT or specialist contrast studies answer selected complications and must not delay sepsis care.

04Treatment approachPreparation, options, escalation and aftercare.

01CLOUDYCloudy peritoneal effluentFirst stepA PD patient reports cloudy drainage, white flecks, abdominal discomfort or systemic illness.

1Tell the patient to contact the PD unit immediately, retain the bag if locally advised and attend the agreed urgent assessment route rather than waiting for the next exchange.
2Assess sepsis and abdominal red flags, examine the exit site and tunnel, and obtain effluent cell count, differential, Gram stain and culture correctly.
3After sampling, start the patient’s current PD-programme empirical intraperitoneal regimen without waiting for results; it must cover both Gram-positive and Gram-negative organisms. Do not substitute a generic agent or dose: centre resistance, allergy, residual function, APD/CAPD schedule, compatibility and dwell time determine the prescription. Add systemic sepsis treatment when indicated.
4Review clinical response and repeat fluid testing as the protocol directs, narrow treatment to culture and remove the catheter when refractory, fungal or other specialist criteria are met.

02DRAINPoor inflow or outflowExchanges are slow, drain volume falls or the cycler repeatedly alarms.

1AlternativeCheck clamps, transfer set, posture, fill volume, recent bowel activity and whether pain, cloudy fluid, leak or hernia indicates an urgent alternative problem.
2Treat constipation using the established PD bowel regimen and ask the trained unit to assess fibrin or approved flush measures; never probe the catheter blindly.
3Obtain catheter-position imaging and surgical or interventional review when conservative correction fails or migration, kinking or entrapment is suspected.
4Provide temporary prescription support through the renal team and use haemodialysis only when clearance or fluid needs cannot safely be met during salvage.

03VOLUMEFluid overload on PDWeight, oedema, blood pressure or breathlessness worsens despite reported exchanges.

1Confirm actual fill and drain records, urine volume, technique, salt and fluid intake, constipation and adherence before changing osmotic strength.
2Assess for heart failure, infection, loss of residual function, dialysate leak and a change in membrane transport or long-dwell reabsorption.
3Optimise dwell pattern, icodextrin or glucose concentration and residual diuretic strategy with the specialist PD prescriber and renal dietitian.
4EscalationEscalate urgently for pulmonary oedema or failed ultrafiltration, considering temporary or permanent modality transfer when PD cannot deliver safe volume control.

04PREVENTTechnique and infection preventionA person starts PD, has contamination or experiences a recurrent infection.

1Reassess hand hygiene, mask and connection practice through supportive observation by a PD nurse, correcting environmental and equipment barriers.
2Follow the centre's exit-site prophylaxis and contamination protocol, including immediate advice after a disconnection or wet contamination event.
3When systemic or intraperitoneal antibiotics are prescribed, consider antifungal prophylaxis according to current PD guidance and individual contraindications.
4Review organism pattern, dental or bowel source, tunnel disease and household support before attributing recurrence to patient fault.

05Regimens, contraindications and interactionsTreatment details and the circumstances that modify them.

Provide rapid Gram-positive and Gram-negative cover for suspected PD-associated peritonitis while culture results are pending.

Empirical intraperitoneal antibiotics

There is no universal agent or dose. Obtain the patient’s current PD-programme protocol and prescribe its intermittent or continuous intraperitoneal regimen after sampling, adjusted for modality, dwell, residual kidney function, allergy, compatibility and local susceptibility data; if that protocol is unavailable, contact PD nephrology and microbiology urgently.

Sepsis may also need systemic therapy; allergies, compatibility within dialysate, dwell time and drug levels for selected agents require specialist pharmacy oversight.

Reduce secondary fungal peritonitis after antibacterial courses, in line with the PD programme's adopted guideline.

Antifungal prophylaxis with antibiotic exposure

Give the centre-approved oral antifungal regimen for the duration specified whenever qualifying antibiotic treatment is used in a PD patient.

Check pregnancy, liver disease, QT and drug interactions, especially with calcineurin inhibitors or warfarin; product choice follows local microbiology policy.

Sustain ultrafiltration during a long dwell when glucose solution performance or exposure is problematic.

Icodextrin peritoneal solution

Use only for the single long dwell and fill volume prescribed by the specialist PD programme.

Use only compatible glucose meters because maltose interference can conceal true hypoglycaemia; rash, sodium changes, sterile peritonitis and fluid depletion require review.

Augment urinary sodium and water removal and reduce reliance on hypertonic peritoneal glucose exchanges.

Loop diuretic with residual kidney function

Titrate a renal-unit oral regimen to urine and volume response while residual diuresis remains clinically useful.

Monitor hearing at high exposure, electrolytes, pressure and dehydration; escalating dose cannot restore urine output after anuria and may threaten residual function if volume is over-reduced.

Prevent constipation-related catheter displacement, poor drainage, discomfort and bacterial translocation risk.

PD bowel regimen

Use the individual's regular osmotic and stimulant laxative plan to maintain soft predictable stools without dehydration.

Exclude obstruction when vomiting, severe pain or absolute constipation occurs; magnesium- or phosphate-containing preparations can accumulate in kidney failure.

06Complications, monitoring and follow-upAdverse effects, response and longer-term review.

Review daily weight, blood pressure, urine volume, net ultrafiltration and oedema pattern, escalating an abrupt fall in drain volume rather than averaging it away.
Track potassium, bicarbonate, calcium, phosphate, haemoglobin, albumin and glycaemia according to the PD programme and after prescription change or intercurrent illness.
Measure residual and peritoneal clearance using timed collections at the centre interval, repeating sooner when symptoms, urine or membrane behaviour changes.
Inspect the exit site and catheter tunnel regularly and record infection organisms and treatment response to distinguish relapse, recurrence and repeat episodes.
Reassess connection competence after peritonitis, hospital admission, cognitive or visual change, new carer involvement and equipment modification.
Monitor nutrition, protein intake, glucose absorption, weight composition and lipid or diabetic control with a renal dietitian rather than applying indiscriminate restriction.
Confirm that the patient and every care setting know the approved glucose meter when icodextrin is prescribed.

07Special situationsVariants, exceptions and circumstances that change the usual approach.

Cloudy bag is a clock

The urgency begins when abnormal effluent is noticed, not when fever or hypotension later confirms systemic illness.

Residual clearance is powerful

A small daily urine volume may add disproportionately useful fluid and solute removal to the peritoneal prescription.

Dwell time changes function

Longer exposure improves some solute equilibration but can permit glucose gradient dissipation and fluid reabsorption in faster transporters.

Constipation moves catheters

Loaded bowel can alter pelvic catheter position and outflow, making bowel review an essential technical intervention.

Technique review is supportive

Observation after infection should find system barriers and retraining needs, not presume carelessness or punish disclosure.

Dialysate glucose is absorbed

The osmotic prescription contributes energy and metabolic load, so nutrition and diabetes plans must account for it.

08Common pitfallsFrequent interpretation and management errors.

01
Do not reassure a patient with cloudy effluent merely because the abdomen is not tender or the temperature is normal.
02
Do not start antibiotics without collecting suitable effluent first when sampling can be achieved without unsafe delay.
03
Do not use oral or intravenous antibiotics alone for uncomplicated PD peritonitis when intraperitoneal treatment is the centre standard.
04
Do not repeatedly escalate high-glucose exchanges without investigating salt intake, membrane change, leaks, constipation and loss of residual function.
05
Do not use an unverified glucose meter in a patient receiving icodextrin-containing dialysate.
06
Do not interpret a Kt/V result as proof of satisfactory treatment while fluid overload, malnutrition or uraemic symptoms persist.
07
Do not force or instrument a poorly draining catheter outside a trained PD access protocol.