Percutaneous nephrolithotomy (PCNL) at The Holly Hospital

What is percutaneous nephrolithotomy?

Percutaneous nephrolithotomy (PCNL) is an operation to remove kidney stones that are too large, or otherwise unsuitable, to treat with less invasive methods. A telescope and instruments are passed into the kidney through a small puncture in your back to break up and remove the stone.

What conditions does it treat?

PCNL treats large kidney stones, generally over 2cm, or stones with an irregular or 'staghorn' shape that blocks part of the kidney's drainage system. It's also used for stones that aren't suitable for shockwave lithotripsy (ESWL) or ureteroscopy, for example because they're too hard or difficult to see clearly on X-ray.

Left untreated, stones like this tend to keep growing and can eventually damage the kidney, even if they aren't currently causing symptoms.

What are the benefits?

PCNL offers the best chance of clearing a large stone in a single procedure, with a reported success rate of around 75% to 98% across studies, which is generally higher than ESWL or ureteroscopy achieve for stones of this size.

It's also faster to recover from, less painful, and has fewer complications than open surgery, which it has largely replaced. Stone fragments removed during the procedure can be analysed to identify what they're made of, helping to reduce the chance of new stones forming.

Are there different types or surgical approaches?

PCNL is most often done lying face down (prone), though some centres use a face-up or side-lying position instead (supine or modified supine), each with its own advantages depending on the stone's location and your individual circumstances. Standard-sized instruments are typical, though smaller 'mini' instruments are used for suitable stones in some centres.

A drainage tube and internal stent are usually left in place afterwards to support healing, though a 'tubeless' approach, with nothing left in place, is increasingly used for suitable cases in some centres. Occasionally, if a stone is very infected, the kidney is drained for a period first before the stone itself is removed in a later, separate operation.

Alternatives to PCNL, which your consultant will discuss with you, include:

• observation: stones smaller than 5mm often pass by themselves, though stones larger than 7mm rarely do
• extracorporeal shockwave lithotripsy (ESWL): shockwaves fired through the skin break the stone into fragments you pass yourself
• flexible ureteroscopy: a thin, flexible telescope is passed up through the bladder and ureter into the kidney, where the stone is broken up with a laser
• open surgery: rarely needed nowadays, and generally only if the other options aren't suitable or don't succeed.

What happens before the procedure?

Urine and blood tests beforehand check your kidney function and rule out infection; if an infection is found, surgery is postponed until it clears. You'll usually need to stop blood-thinning medicines, such as warfarin, aspirin or clopidogrel, beforehand, after discussing timing with your team.

A pre-assessment appointment checks your fitness for surgery and the anaesthetic, so it's important to attend, since missing it can delay or cancel your operation. On the day, you'll need to:

• stop eating for 6 hours beforehand, though clear, non-fizzy fluids are allowed up to 2 hours before
• sign a consent form and have the correct side marked
• wear compression stockings to help reduce the risk of blood clots
• bring all your usual medicines, including anything bought over the counter or herbal remedies

What happens during the procedure?

1. You're given a general anaesthetic, occasionally a spinal anaesthetic instead, so you're asleep or numb from the waist down throughout.
2. A telescope is passed into your bladder and a fine tube guided up to the kidney, so contrast dye can be injected to show it clearly on X-ray.
3. You're turned onto your front, or occasionally another position, and the kidney is punctured through the skin of your back with a fine needle, guided by X-ray or ultrasound.
4. The needle track is gradually stretched to create a passage sized to fit the telescope being used.
5. The telescope is passed along this track to find the stone, which is broken up using a laser, a mechanical device or an ultrasound probe, and the fragments are removed.
6. A temporary drainage tube or internal stent, along with a bladder catheter, is often left in place to support healing and drainage.

The procedure typically takes 1 to 3 hours, depending on the size and complexity of the stone.

What does recovery look like?

In hospital

You're cared for in a recovery area until awake, which can take an hour or two, and encouraged to move your feet and ankles in bed to aid circulation, before returning to the ward. A bladder catheter is usually removed the morning after surgery, and a kidney drainage tube within a day or two, sometimes confirmed by an X-ray first.

If an internal stent was left in place, this is usually removed a few weeks later in a short, separate procedure under local anaesthetic, taking only a few minutes. Hospital stays are reported anywhere from 1 to 5 days depending on the centre and your individual recovery, with 2 to 3 days typical, and an X-ray or scan the day after surgery checks whether all the stone has been cleared.

At home

Some blood in your urine is normal for up to about 2 weeks. Drink plenty of fluids, aiming for around 2 litres (about 3.5 pints) a day, or twice your normal intake for the first 24 to 48 hours, to help flush your system and reduce the risk of infection or blockage.

Expect some soreness for several weeks, which painkillers can help with, and avoid heavy lifting or straining for about 4 weeks. Avoid lying still for long periods too, since this raises the risk of chest infection or blood clots.

Most people return to work within 1 to 2 weeks, up to 4 if the job is physically demanding, and shouldn't drive until able to perform an emergency stop confidently, checking with their insurer beforehand. A follow-up appointment, typically 6 to 8 weeks later though this varies by centre, checks your recovery and whether any stone fragments remain, and your team can advise on diet and fluid changes to help prevent new stones forming.

What are the risks and complications?

As with any operation, PCNL carries some risks:

• mild bleeding into the urine: expected in almost everyone, and settles by itself
• needing a temporary bladder catheter: most patients
• urinary infection needing antibiotics: about 1 in 10 to 1 in 2
• needing more than one puncture site to clear the stone: about 1 in 10 to 1 in 2
• some stone fragments remaining, needing further treatment: about 1 in 20 to 1 in 5
• new stones forming again over the next 5 to 10 years, needing further treatment: about 1 in 2
• sepsis (a serious infection) needing an unexpected intensive care admission: about 1 in 100 to 1 in 10
• moderately severe bleeding needing a procedure to block the blood supply (embolisation): about 1 in 100 to 1 in 50; some sources report around 5 in 100 needing a blood transfusion
• not being able to get proper access to the kidney, needing further surgery or a different approach: about 1 in 100 to 1 in 50
• infection at the puncture site in your back: about 1 in 100
• anaesthetic or heart and circulation problems possibly needing intensive care: about 1 in 250 to 1 in 50
• serious damage to the kidney's blood vessels needing emergency removal of the kidney: less than 1 in 1,000
• rarely, injury to the lung, bowel, spleen or liver needing surgery
• a general hospital-acquired infection risk of around 4 to 6 in 100 overall, though specific risks such as MRSA colonisation and bloodstream infection are individually much rarer.