Authors: Idorenyin Cletus Akpayak (Department of Surgery, Division of Urology, Jos University Teaching Hospital, Jos, Nigeria), Chukwudum Dennis Ikeh (Department of Surgery, Division of Urology, Jos University Teaching Hospital, Jos, Nigeria)
Categories: Original Article, Minimally invasive surgery, percutaneous nephrolithotomy, renal stones, Calculs rénaux, chirurgie mini-invasive, NLPC
Source: Annals of African Medicine
Doi: 10.4103/aam.aam_5_25
Authors: Idorenyin Cletus Akpayak, Chukwudum Dennis Ikeh
Percutaneous nephrolithotomy (PCNL) is considered one of the most significant advances in minimally invasive urologic surgery. It offers a better stone-free rate compared to other available treatment modalities of renal stones at a lower complication rate compared to open surgery. Despite the availability of extracorporeal shock wave lithotripsy and flexible ureteroscopy, PCNL remains the gold standard modality for large and complex renal stones. Here, we review our initial experience with standard PCNL in the prone position for renal stones >1.5 cm with respect to stone clearance rate and complications as seen in our patients.
Records of 24 patients who had standard PCNL and pneumatic lithotripsy between September 2020 and September 2023 were reviewed retrospectively. All the patients who had the standard PCNL for renal stones >1.5 cm were the subjects of this study. Data on patients’ demographics, indication for the surgery, location of stone, size of stone, postoperative nephrostomy placement, nephrostomy tract size, complications, duration of surgery, duration of hospital stay, and status of stone clearance were obtained, and the data were subjected to statistical analysis.
A total of 24 patients underwent the standard PCNL. The mean age of the patients was 47.0 ± 10.28 years (16 males and 8 females; 17–68 years). Flank pain was the main indication for the surgery. The mean stone size was 2.5 cm (range: 1.6–3.3 cm). The mean Hounsfield unit was 1248.2 HU (range: 927–1502HU). At a single session, we achieved 100% stone clearance in 20 (83.3%) patients. Two (8.3%) of our patients required a second session of PCNL due to intraoperative bleeding and perforation of the pelvicalyceal system necessitating termination of the procedure and insertion of nephrostomy tube. In another 2 (8.3%) patients, the stones migrated and became inaccessible. One (4.2%) patient stayed for 10 days due to persistent urine leak, which eventually stopped after the insertion of a double-J stent and administration of antibiotics. The Clavien–Dindo grading system was used to classify postoperative complications. A total of 14 (58.3%) patients had Grade I complications, while 3 (12.5%) patients had Grade II and 1 (4.2%) had Grade IIIa complications.
PCNL is an effective minimally invasive technique for the treatment of large renal stones. Our initial experience suggests that the complication rate in PCNL is well within the acceptable limit.
Percutaneous nephrolithotomy (PCNL) was first introduced as a therapeutic option for renal stones in 1976 by Johansson and Fernström.[1] The technique was further refined by Peter Alken and other reputable PCNL pioneers.[23] It is currently the gold standard in the treatment of large and complex renal stones.[45]
PCNL is considered one of the most significant advances in minimally invasive urologic surgery and still stands at the forefront of innovations as well as excellence in urologic surgery.[6] It offers a better stone-free rate (SFR) when compared to other available minimally invasive modalities for the treatment of renal stones and at a lower complication rate compared to open surgery.[789] Hence, despite the availability of extracorporeal shock wave lithotripsy and flexible ureteroscopy (fURS), PCNL remains the modality of choice for large and complex renal stones.[45]
In addition, further improvements and innovations in stone disintegration devices, including yttrium–aluminum–garnet laser, thulium fiber laser, and combination of pneumatic and ultrasonic lithotripter (e.g., Swiss LithoClast Master) as well as Swiss LithoClast Trilogy and ShockPulse lithotripters, have contributed significantly to the desirable high SFR offered by the PCNL.[10]
PCNL is traditionally carried out in the prone position.[1112] Recently, there has been a vigorous campaign by many experts who want PCNL to be performed in the supine position. Yet, the perceived advantages of the supine position for PCNL have not shown clinical superiority when compared to the more familiar prone approach.[1314] Performing PCNL in the traditional prone position has cognate advantages and still enjoys many proponents. These advantages include, but not limited to, easier access to all calyceal systems and increased space for renal puncture.[1415] In terms of anesthesia, Edgcombe et al.,[16] in their review of anesthesia in the prone position in 2008, recognized that anesthesia in the prone position is safe once there is a clear understanding of the physiologic changes and risk associated with the position.
Standard PCNL, which implies the use of nephroscope size 22Fr and above, has encountered several modifications/miniaturizations over the years in an attempt to reduce, particularly the bleeding complication of the PCNL. Currently, this modification has given rise to miniPCNL, SuperminiPCNL, ultraminiPCNL, and microPCNL.[1718] The standard PCNL, however, still enjoys higher SFRs when compared to her miniaturized congeners, especially for large and complex renal stones and therefore still widely practiced.[1920]
While PCNL has gained widespread popularity and its outcomes widely reported in many regions of the world, literature on the subject is lacking in our environment. We, therefore, review our initial experience with standard PCNL in the prone position for renal stones >1.5 cm with respect to stone clearance rate and complications, particularly bleeding, sepsis, and urinary leakage as seen in our patients.
A total of 24 patients who underwent PCNL and pneumatic lithotripsy between September 2020 and September 2023 were enrolled retrospectively. This hospital-based retrospective study was carried out at Dica Frontier Hospital in Jos, North Central Nigeria. The patients who had the standard PCNL for renal stones measuring more than 1.5 cm or more located within the lower calyx, midcalyx, or the renal pelvis were included in this study. All the patients were thoroughly evaluated and had complete blood count, urinalysis, and urine microscopy/culture/sensitivity. They also had serum electrolytes/urea/creatinine and clotting profile. Where indicated, chest X-ray, electrocardiogram, and echocardiogram were done before surgery. All patients had computed tomography (CT) urography preoperatively to locate the stone, measure its size, and plan the renal access. Patients who had isolated upper calyceal stone were treated mostly by fURS and were therefore excluded from this review. All anticoagulation and antiplatelet treatment were stopped for the appropriate duration of time before surgery.
Data on patients’ demographics, indication for the surgery, location of stone, size of stone, postoperative nephrostomy placement, nephrostomy tract size, intraoperative and postoperative complications, blood transfusion, duration of surgery, duration of hospital stay, and status of stone clearance were obtained. The data were entered into and analyzed using SPSS^®^ version 22 (IBM Corporation, Armonk, New York, US).
The PCNL was performed under general anesthesia with muscle relaxation. The patient was first placed in the lithotomy position, and cystoscopy was carried out to gain retrograde access to the ureter with cannulation of the ipsilateral ureteric orifice with a 5Fr ureteral catheter. Retrograde pyelogram was then performed with Ultravist-300 in 1 dilution to delineate the anatomy of the pelvicalyceal system (PCS). Then, the patient was repositioned in the prone position with pillows under the chest and the pelvis. Soft padding was ensured for pressure points at the knees and head to avoid pressure sores.
Percutaneous access was then obtained with a size 18G puncture needle with the guide of fluoroscopy using biplanar technique. The needle was angled at 40°–60° against the skin at about the posterior axillary line. Mental estimation of the depth of the calyx was done with the C-arm at anteroposterior position. The C-arm was then turned oblique toward the surgeon to confirm the depth. Minor adjustment in the angle of the puncture, where required, was carried out by withdrawing the needle almost to the skin. Confirmation of the correct position of the needle was noted with the egress of urine. A size 0.035 inch Cobra guidewire was placed under the fluoroscopy image guidance to coil in the pelvis, upper calyx, or preferably down the ureter. Dilatation was carried out first with an 8Fr size fascial dilator and then serially with Amplatz dilator, up to 26Fr or 28Fr size and an Amplatz sheath placed over the dilator. The dilatation was monitored throughout by fluoroscopy. Nephroscopy was then carried out using a size 24Fr nephroscope (Richard Wolf medical instrument). The stones were fragmented using a 2.0 mm pneumatic lithotripter probe (Lithomed) and the fragments were removed using biprong or triprong forceps. Irrigation was achieved with normal saline mostly under gravity with pressure increased only when vision became poor. In all patients, the C-arm (Adonis Medical Systems) was used to guide the steps of the procedure. The principle of ALARA was duly followed and all theater personnel had adequate protection by wearing lead aprons and thyroid shields.
A nephrostomy tube (size 18Fr) was placed at the end of the procedure in all patients. A Foley catheter was left in place to rest the bladder and monitor bleeding. The catheter was removed on the 2^nd^ day after the operation. Intravenous antibiotics were given for 48 h postoperatively and subsequently oral antibiotics. The nephrostomy tube was left on free drainage for the first 24 h and then clamped for another 24 h. It was then removed 72 h postoperatively and patients discharged home if there was no pain or urine leakage. Postoperative analgesia consisted of parenteral pentazocine for 24 h and then oral nonsteroidal analgesics thereafter.
At follow-up, radiological investigations were tailored to postoperative clinical evaluation of the patients and included plain abdominal X-ray and CT urography. Complete stone clearance was defined as complete resolution of symptom (flank pain) that warranted the procedure and absence of stone on radiological evaluation.
The perioperative complications were evaluated using the Clavien–Dindo grading system [Table 1].[21] The Clavien–Dindo scores were given based on the type of treatment required to manage a given complication. Specifically, in adopting this most acceptable grading system, for PCNL, urine leakage from the access site for <24 h was considered a gGrade 1, while urine leak lasting more than 24 h was recorded as Grade 2 complication because it necessitated prolonged hospitalization. Whereas, persistent urine leak (PUL) that necessitated cystoscopy and double-J (DJ) stent placement was considered a Grade 3 complication.[22]
A total of 24 patients underwent the standard PCNL in the prone position. The mean age of the patients was 47.0 ± 10.28 years (range: 17–68 years), consisting 16 males and 8 females. Flank pain was the main indication for the surgery. All the patients had general anesthesia.
The mean stone size was 2.5cm (range, 1.6– 3.3cm). The mean stone Hounsfield unit was 1248.2HU (range, 927 – 1502HU). Most of the stones were located in the renal pelvis (13, 54.2%), while 5 (20.8%) were calyceal and 3 (12.5%) were staghorn stones. One patient (4.2%) had a co-existing stone in the middle calyx and the renal pelvic stone [Table 2].
At a single session, we achieved 100% stone clearance in 20 (83.3%) patients. Two (8.3%) patients required a second session of PCNL due to intraoperative bleeding and perforation of the PCS necessitating termination of the procedure and insertion of the nephrostomy tube. In another 2 (8.3%) patients, the stones migrated and became inaccessible.
The mean intraoperative time was 71.05 ± 19.07 min. The mean hospital stay for the patients was 3.2 ± 2.7 days. One (4.2%) patient stayed for 10 days due to PUL, which eventually stopped after insertion of the DJ stent and administration of antibiotics.
All patients had normal of haemoglobin concentration prior to surgery. The Clavein-Dindo grading system was used to classify postoperative complications. A total of 14 (58.3%) patients had Grade I complication while 3 (12.5%) patients had Grade II complications [Tables 3 and 4].
PCNL is recommended by the European Association Urology (EAU) guideline as the first-line surgical strategy for renal stones 2 cm and above.[4] Our study included patients with stone size above 1.5 cm as PCNL is an still excellent modality for even lower stone sizes, particularly as the alternative fURS comes with high expense and mostly out of the reach of our patients.
The popularity that PCNL enjoys is primarily related to its ability to render patients stone free compared to other minimally invasive strategies for renal stone treatment.[78] The recorded SFR for renal stones by many authors following PCNL ranges from 66% to 93.3%.[232425] The SFR in our patients was 83.3%, which is within the recorded range.
Part of the reason for variations in the reported SFR may be due to the imaging modality used in the postoperative evaluation of patients. The imaging modality used in this assessment has not been uniform by the authors and ranges from X-ray alone, ultrasonography alone, the combination of X-ray and ultrasonography, or the use of CT. Furthermore, the postoperative assessment of the stone-free status and the definition of what constitute stone-free status (<2 mm, <4 mm or no fragments) have not been agreed upon.[26] The reasons behind the undesirable residual fragments (RFs) include multiple stones, staghorn stones, stone migration, presence of stone in an inaccessible calyx, complex PCS anatomy, and termination due to bleeding or perforation of the PCS. In our series, 4 (16.7%) patients had residual stone fragments. The RF was due to stone migration in 2 (8.3%) patients, while in another 2 (8.3%) patients, it was due to bleeding and perforation of the PCS.
Although PCNL efficacy is unmatchable with other minimally invasive treatment strategies, it is associated with relatively higher complication rates.[2728] The Clavien–Dindo classification system is recommended by the EAU guidelines to standardize the reporting of the perioperative complications of urologic surgeries including PCNL.[29] Based on the Clavien–Dindo classification, most of our patients had Grade 1 complications mainly due to bleeding and postoperative urine leakage. Similarly, 2 (8.3%) patients had Grade 2 complications which were due to bleeding and urosepsis.
Most of the bleeding during PCNL arises from the renal parenchyma and in most cases is not significant. However, significant bleeding requiring blood transfusion can occur.[30] The recorded independent risk factors for bleeding complication during PCNL include large tract size, supracostal access, multiple access, perforation of the PCS, and increasing intraoperative time.[31] In PCNL, excessive bleeding requiring blood transfusion may result from injury or tear of the PCS resulting in injury to the infundibular vessels that lie close to the infundibulum. Infundibular tear occurs principally during tract dilatation or during stone manipulation.
Most of our patients had minor bleeding, and we encountered bleeding necessitating blood transfusion in 4.2% of our patients. This was related to the perforation of the PCS and also warranted the suspension of the procedure due to poor vision.
Following PCNL, sepsis can occur due to pyelolymphatic, pyelovenous, and pyelotubular backflow as well as forniceal rupture.[30] We documented urosepsis in 8.3% of our patients. Various authors have found postoperative sepsis/fever in 15%–30%.[323334]
PCNL is carried out in an uncomplicated stone or complicated stone scenario, giving rise to a clean-contaminated and contaminated wound, respectively. In addition, many risk factors are associated with sepsis following PCNL. These include but not limited to positive urine culture, pyonephrosis, staghorn stone, diabetes, anomalous kidney, prolonged operative time, multiple renal access, and nephrostomy tube placement.[32] In our study, of the two patients who developed sepsis, one had type II diabetes mellitus and postoperative PUL. These resolved following antibiotics treatment and DJ stenting, while sepsis resolved in the other patient with only antibiotics treatment.
Nephrostomy tube (NT) placement after PCNL helps achieve hemostasis and prevent urinoma formation from urine extravasation.[35] However, urine leakage from the access site after removal of the NT remains an uncomfortable problem for many patients.[36]
Tefekli et al.[37] modified the Clavien–Dindo classification and scored urine leak lasting more than 24 h as a Grade 2 complication. Blood clots, edema residual stone fragments, and the presence of hydronephrosis are the common factors responsible for this bothersome complication.
In our study, 37.5% of patients had various degrees of urine leak after removal of the NT lasting <24 h. Shin et al.[38] similarly found that 15% of their patient had urine leak for <24 h. We used gauze and Gamgee dressing to reduce the soilage of the patients clothing and the beddings within this period.
In 1 (4.2%) of our patients, the leak lasted for 1 week necessitating cystoscopy and the insertion of a DJ stent which eventually stopped the urine leak. Lee et al.[39] also had applied DJ stenting to stop urine leak post-PCNL in 1.5% of their patients who developed PUL that lasted more than 1 week. PUL prolongs hospital stay and could defeat the minimally invasive advantage conferred by PCNL. Most authors recommend the insertion of a DJ stent if urine leak exceeds 48 h to reduce the hospital stay.[40]
In our series, we treated 3 (12.5%) patients with staghorn stones. PCNL is more challenging when used in the treatment of staghorn stones. The complication rate of 7%–27% was reported by different authors.[2728] The higher rate of bleeding, sepsis, and other morbidity is closely associated with multiple tracts that are sometimes required for satisfactory stone clearance, longer operative time, etc.
One (4.2%) of the patients with the staghorn stone also had an anomalous kidney which, in this case, was a horse-shoe kidney. Renal stone is one of the most common complications of the horse-shoe kidney.[41] However, in general, the complication rates reported for PCNL in horse-shoe kidney is as for normal renal units.[42] We did not encounter unusual complications with our patient.
In our study, we did not encounter rare complication such as colonic perforation, solid-organ (liver and splenic) injuries, or thoracic injuries (hemothorax, hydrothorax, pneumothorax, and nephron-pleural fistula). We carried out CT urography in all our patients before surgery and carefully screened out patients at risk of colonic, splenic, and liver injuries to avoid this complication.
While PCNL for experts is a routine procedure, for the PCNL surgeon still on the learning curve, every step of the procedure could be intimidating. Challenges such as poor logical analysis of the fluoroscopic images, choosing the wrong entry calyx, tract loss, overdilatation, equipment failure, and inability to deal with clots at nephoscopy can bear catastrophic consequences and lead to failure of the procedure.[40] We had encountered kinking of guide wire, tract loss and PCS perforation/overdilation in 4.2%, 8.3% and 33.3% respectively of our patients in the initial stages of our series.
We recognize that our study has limitations. On the one hand, the retrospective data collection comes with its inherent weakness. On the other hand, with the small sample size, it could be said that the findings may not be generalized to the large population. However, we feel strongly about sharing our findings, as this technique is currently making in-roads into our environment and would serve as a reference for larger-scale prospective studies in the future.
Standard PCNL is an efficient minimally invasive technique with respect to lower and treatable complication rates, short hospital-stay, and excellent stone clearance rate.
There are no conflicts of interest.