PCNL (percutaneous nephrolithotomy, keyhole surgery through the back to remove kidney stones) is used for large and complex kidney stones, and like any operation it can have complications. In November 2018 I led a case discussion session on PCNL. The format was simple: I showed each case one step at a time and, at each turning point, asked the room what they would do next.
I opened with the different ways stone disease can present, including a patient with obesity, diabetes, high blood pressure, raised cholesterol and multiple stones. Then we worked through two cases. Both involved the veins of the kidney. The details below are limited to what matters for the teaching point.
Case one: a view that looked wrong
The first case was a complete staghorn stone, a large stone that fills and branches through the kidney's drainage system, which was relatively radiolucent, meaning it showed up faintly on X-ray. With the patient lying face down, we made a fluoroscopy guided puncture (using live X-ray imaging) into an upper calyx, one of the cup-shaped chambers at the top of the kidney. Two guidewires were passed down the ureter, the tube that drains the kidney to the bladder, and a 15 French metal sheath for mini PCNL was inserted.
Through the telescope, the expected view was the lining of the kidney's collecting system and the stone. Instead, we saw pale, smooth lining, the saline flow was falling, and there was a pulsing red blush. That combination was the first warning sign.
When the telescope was taken out, no blood came from the sheath. The vital signs were stable and the urine in the catheter was clear. A guidewire passed through the sheath moved freely up and down the inferior vena cava, the large vein that returns blood from the lower body to the heart. Contrast dye confirmed it: the sheath was sitting in a branch of the renal vein.
Managing the sheath in the vein
The next step was to pass a ureteric balloon dilator through the sheath and inflate it to 4 bar. There was no active bleeding anywhere, and the vital signs stayed stable.
On the third day after surgery there was still no active bleeding, the vital signs were stable and the urine was clear. The lesson for the room was to stop, recognise an unfamiliar view early, and confirm where the sheath is with contrast before deciding what to do.
Why bleeding happens during PCNL
The case led into a wider discussion of the causes of bleeding. A very dilated drainage system, or previous open surgery on the kidney, adds risk. So does a puncture that runs parallel to a calyx through the kidney tissue, where it can meet an artery or vein, or one that overshoots into the tissue and slices the lining off its bed.
Other causes include a patient's own tendency to bleed and too much twisting force from the telescope or the Amplatz sheath (the working tube placed through the tract) when trying to reach a nearby calyx. Perforating the vessels that run under the ribs can cause bleeding, as can stretching a narrow calyx neck with a sheath that is too large for it.
How I approach bleeding in theatre
My first rule is to stop and evaluate. Is the bleeding from an artery or a vein, how much is there, what caused it, and are the vital signs dropping? The Amplatz sheath can be blocked for 7 to 10 minutes, and a Foley catheter (a tube with a small balloon at its tip) with the balloon inflated to 3 ml may be used for this. Advancing the sheath to cover the bleeding point is another option, and so is stopping the procedure.
Two things can make matters worse. Fast irrigation, pushing fluid through quickly to clear the view, can aggravate the problem. And pneumatic lithotripsy, which breaks stones by mechanical impact, is best avoided in this situation; laser is the better choice.
Case two: stones that disappeared
The second patient had a first PCNL, face down, using mini PCNL instruments. Most of the stones were removed, but venous bleeding stopped us from going further. A few days later we carried out a second-look nephroscopy, a planned return to the kidney with the telescope, through a 16 French Amplatz sheath.
Small stones were visible through the mini PCNL telescope. Then, suddenly, two of them could not be seen, either through the telescope or on fluoroscopy. Contrast dye passed through the sheath and filled the vena cava. That raised the possibility that the stones had entered the venous system.
The procedure was stopped and a 12 French Foley catheter was placed through the Amplatz sheath. I made sure everyone in the operating theatre knew about the possibility of stone embolism, meaning stone fragments travelling in the bloodstream. After surgery the patient had an irritating dry cough, but few breathing symptoms, and the chest sounded clear.
By the third day there was no active bleeding, the vital signs were stable and the urine was clear. The remaining stones were later treated with RIRS (retrograde intrarenal surgery, using a flexible telescope passed up through the bladder and ureter), and the two missing stones could not be found in the kidney at that procedure.
What the two cases teach
Both cases turned on the same skill: noticing early that the view does not match what you expect, then confirming the position of the sheath with contrast before acting. Both also show the value of a calm, step-by-step response: control the vein, stop when needed, tell the whole team, and follow the patient closely. These are the lessons I wanted every surgeon in the room to take home.