Percutaneous Nephrostolithotomy for Treatment of Impacted Ureteropelvic Junction Calculus

Abstract

Percutaneous nephrostolithotomy (PCNL) is a minimally invasive urologic procedure used to treat large kidney stones or stones which are not accessible from a retrograde approach. When untreated, these stones can cause chronic pain, infections, and over time, decreased renal function. The indications for PCNL include total renal stone burden greater than 20 mm, lower pole stone burden greater than 10 mm, or any stone burden which cannot be treated with ureteroscopy or extracorporeal shockwave lithotripsy, such as in the setting of a ureteral stricture or ureteropelvic junction obstruction. During the procedure, the patient is typically positioned prone, and a needle is used to puncture the kidney through the flank. As in the case of our procedure, a pre-existing nephrostomy tube can also be used. After wire access to the kidney is obtained, the tract is dilated and an access sheath is placed to facilitate irrigation and insertion of instruments. Large stones can be removed through ultrasonic lithotripsy, pneumatic (ballistic) lithotripsy, laser lithotripsy (typically holmium:YAG or thulium lasers), and combination devices that integrate ultrasonic and pneumatic mechanisms. Smaller stones, such as in our case, can be extracted using graspers. In this video, we present a left-sided PCNL in which we remove a total of 2.1 cm of renal stone burden. Following stone removal, a ureteral stent and nephrostomy tube were placed to enable maximal drainage of the kidney. Postoperative CT showed complete clearance of stone burden.

Keywords

Percutaneous nephrostolithotomy; percutaneous nephrolithotomy; nephrolithiasis; kidney stone.

Case Overview

Background

Nephrolithiasis is a common condition with a prevalence of approximately 10% in the United States.¹ Approximately 1 in 11 patients will experience a kidney stone episode in their lives, and the presence of stone event yield a 50% risk of subsequent stone episodes.² Renal calculi are most commonly formed from calcium oxalate, though other types such as calcium phosphate, uric acid, ammonium acid urate, protein matrix, cystine, and certain drugs are possible. The most common modifiable risk factors for stone formation include dehydration, obesity, hypertension, diabetes, and dietary intake.²

While most small stones may be managed medically and can pass spontaneously, up to 30% require surgical intervention, and this risk increases with larger stone size.³ Shockwave lithotripsy (SWL) or ureteroscopy (URS) with laser lithotripsy are recommended in symptomatic patients with less than 20 mm of stone burden, excluding the lower renal pole.⁴ SWL or URS can be used for lower pole stones measuring less than 10 mm, but only URS is recommended for lower pole stones larger than 10 mm.⁴ PCNL can be used in any instance where there is large renal stone burden or the stones are not accessible by SWL or URS.^4,5 PCNL has a higher stone-free rate for stones greater than 10 mm in size.

Focused History of the Patient

The patient is a 71-year-old female with history of hypertension, coronary artery disease with drug-eluting coronary stents on clopidogrel and aspirin, heart failure with reduced ejection fraction, atrial fibrillation status post cardioversion, stage III chronic kidney disease and low anterior resection with end colostomy for colon adenocarcinoma. She presented initially with severe left flank pain. On CT imaging of the abdomen, she was found to have a left-sided, 2.1-cm renal calculus at the ureteropelvic junction (UPJ) with chronic-appearing hydronephrosis. She underwent nephrostomy tube placement for drainage of the kidney. Given the significant degree of atrophy in the left kidney, we determined that it would not be possible to access the stone through a retrograde approach, so the patient was scheduled for a left PCNL.

Her preoperative urine culture showed 50,000–100,000 colonies/mL of mixed urogenital flora for which she was treated with trimethoprim-sulfamethoxazole. The patient stopped taking clopidogrel 5 days prior to surgery and she was deemed ASA class III by our anesthesiologist.

Physical Exam

The patient was afebrile with normal heart rate and blood pressure. She had a nephrostomy tube protruding from the left flank and draining clear yellow urine. There was mild tenderness to palpation over the left flank at the site of the nephrostomy tube.

Imaging

The patient underwent a preoperative non-contrast CT of the abdomen and pelvis which showed an atrophic left kidney with the nephrostomy tube positioned in the renal pelvis. There was a 2.1-cm stone at the left UPJ in addition to the smaller stones/calcifications in the lower pole of the kidney.

Natural History

Non-obstructing kidney stones typically do not cause symptoms unless they shift and cause obstruction of the urine flow out of the kidney, which can occur at the UPJ or anywhere along the ureter. Most types of renal calculi do not typically dissolve and may grow over time, depending on the patient’s metabolism, excretory function, and dietary habits. Many small, non-obstructing stones may remain asymptomatic for long periods of time.⁶ Chronic stones may enlarge into staghorn calculi over time, occupying the entirety of the kidney. These stones may cause flank pain from obstruction or recurring urinary tract infections. Untreated chronically obstructing stones may result in renal atrophy and damage, as in the case of our patient.⁷ This predisposes the patient to chronic kidney disease, end stage renal disease, and hypertension.^7-9

Options for Treatment

Three main options exist for treatment of kidney stones. The first is extracorporeal shockwave lithotripsy, which uses focused shock waves targeted at the stone to fragment it within the kidney or proximal ureter.⁴ This method relies on spontaneous stone passage following the lithotripsy and is intended for small stones. The second option involves retrograde ureteroscopy, in which a flexible or rigid ureteroscope is inserted through the urethra, bladder, and ureter into the kidney.⁴ A holmium or thulium laser is used to fragment the stone, and large fragments are removed using a wire basket. The final technique, which is demonstrated in this video, involves PCNL, in which a puncture through the flank is made into the kidney, and this access is used to directly remove stones from the kidney.⁴ This may be combined with laser or ultrasonic lithotripsy, pneumatic (ballistic) lithotripsy, or a combination devices that integrate ultrasonic and pneumatic mechanisms depending on the size and location of the stones within the kidney.

Rationale for Treatment

The goal of PCNL is to relieve flank pain and reduce the risk of infection caused by large kidney stones. This is done through complete removal of all stone fragments where possible.

Special Considerations

Patients with very large stones are best suited for PCNL as it has the highest stone-free rate. Patients on anticoagulation should discontinue this in the appropriate timeframe to decrease the risk of perioperative bleeding complications.¹⁰ In patients with recurring urinary tract infections, antibiotic treatment should be initiated for at least 7 days preoperatively to reduce sepsis risk.¹¹

Discussion

Nephrolithiasis is a common condition which affects 1 in 11 individuals.² Although many renal calculi are treated with conservative management, surgical intervention is occasionally required. PCNL is typically used to surgically manage large renal calculi greater than 2 cm in size and often require the use of laser, ultrasonic, and/or pneumatic lithotripsy devices.⁴ In this procedure, we were able to retrieve multiple stones through an established tract with only the use of endoscopic stone grasping forceps, as lithotripsy was not required.

The first step of PCNL involves access into the kidney through the flank. This can be performed using interventional radiology access through a pre-placed percutaneous nephrostomy tube or may be done by the surgeon on the day of the procedure. Multiple techniques exist for surgical percutaneous access. The most common method involves the use of fluoroscopy to triangulate to the renal calyces with the use of a spinal needle.¹² A ureteral catheter is often placed to inject opacifying contrast into the renal collecting system to aid in targeting. Ultrasound guidance can also be used, with the surgeon visualizing the target calyx and advancing the needle with or without additional fluoroscopy.¹³ The final technique involves retrograde access into the kidney with insertion of a retrograde percutaneous needle which originates in the target calyx and exits the patient’s flank.¹⁴

The most common complications with PCNL include bleeding, sepsis, and positioning-related injuries.¹⁵ Prone position is the most common approach used for PCNL. Patients with pre-existing comorbidities also are at increased risk of cardiopulmonary compromise when positioned prone. For this reason, the patient is flipped from supine to prone position from the stretcher to the operating table, and the stretcher remains in the operating room until the anesthesiologist can confirm the patient has adequate hemodynamic and ventilatory parameters to proceed with PCNL. If the patient exhibits hemodynamic instability, the patient may be quickly returned to the stretcher in the supine position. Finally, musculoskeletal positioning injuries such as neurapraxias should be considered, with adequate padding and support for the patient’s extremities.

There has been a trend toward positioning modifications for PCNL. The split-leg position allows for access to the urethra for retrograde stone treatment simultaneous with PCNL to perform endoscopic combined intrarenal surgery, thereby reducing total operative time.¹⁶ In select patient scenarios, variations of supine positioning have gained momentum as a method to reduce operative time, reduce complication rates, and facilitate retrograde procedures.^17-19 Supine positioning has also been associated with the use of smaller access sheaths in mini-PCNL, further reducing the risk of postoperative complications.²⁰

In this procedure, we used an existing percutaneous nephrostomy tube to access the left kidney and performed a left PCNL for an impacted renal calculus at the UPJ. Another non-obstructing stone was also removed. A ureteral stent was able to be placed across the UPJ for optimal drainage of the kidney. A Foley catheter was placed through the nephrostomy tract (acting as a nephrostomy tube) to promote hemostasis and serve as an additional outlet for drainage. The total blood loss in the procedure was minimal, and the total operating time was one hour. A non-contrast CT of the abdomen and pelvis postoperatively revealed complete clearance of stone burden from the left kidney. Her nephrostomy tube was clamped on postoperative day 1, and there was no leakage of urine around the flank incision, indicating adequate drainage of urine into the bladder. Her flank remained dry and the urethral catheter was removed. The patient was discharged on postoperative day 2. The patient was seen one month later and was found to be doing well without any flank pain. Her ureteral stent was removed one month later with plans to continue surveillance of her nephrolithiasis with a CT abdomen and pelvis in three months.

Equipment

• Olympus offset rigid nephroscope with graspers.
• Boston Scientific NephroMax High Pressure Nephrostomy Balloon Catheter Kit.
• Boston Scientific Sensor nitinol guidewire and Amplatz Super Stiff guidewire.
• Boston Scientific 10-French Dual Lumen Ureteral catheter.
• Boston Scientific 6-French x 26-cm Contour ureteral stent.
• 20-French council tip Foley catheter.
• #11 Blade scalpel.
• 2-0 Nylon suture.

Disclosures

Nothing to disclose.

Statement of Consent

The patient referred to in this video article has given her informed consent to be filmed and is aware that information and images will be published online.