Treatment of Kidney Stones by Percutaneous Nephrolithotomy: Evaluation of the Results of the First Series of Our Experience in the Urology Department of the Idrissa Pouye General Hospital in Dakar ()
1. Introduction
Urinary lithiasis is defined as the presence of crystal concretions or stones in the urinary tract. This pathology is increasingly frequent in our regions due to changes in dietary and professional habits and affects the younger population [1] . Its major symptomatology is nephritic colic-like lumbar pain. This pathology, considered benign, can be serious in certain cases because it is most often the cause of renal destruction (pyonephrosis), which is still frequent in our regions [2] .
The treatment of urinary lithiasis and endo-urology underwent a revolution worldwide with the advent of modern, minimally invasive techniques: percutaneous nephrolithotomy (PCNL), ureterorenoscopy (URS) and extracorporeal shock waves lithotripsy (ESWL). Percutaneous nephrolithotomy is, in most comparative studies and meta-analyses in the literature, the most effective technique with 90% - 97% efficacy, while that of Flexible URS varies from 70% - 95% for stones larger than 10 mm [3] [4] . Compared to ESWL, the overall success rate at three months for kidney stones is 70% - 80% [5] .
The principle of PCNL is the extraction of renal or ureteral calculi through a nephrostomy tunnel created by a transcutaneous route allowing the passage of endoscopic instruments to crush, pulverize or extract the calculi. This technique represents a very important advance that has significantly reduced the number of lumbotomies performed in young patients for benign lithiasis, especially given the technical progress and miniaturization of the instrumentation. Its complications are essentially hemorrhagic, infectious, and lesions of the neighboring organs [6] [7] [8] .
PCNL was performed for the first time in Senegal at the Urology Department of the Hospital General Idrissa Pouye (HOGIP) in 2015. While this technique is well codified in Western countries and Asia with a lot of data available in the literature, PCNL is still in its infancy in Sub-Saharan Africa. Thus, we have not found any related publications in West Africa. It is therefore important to describe the first experiences with this technique to use the interest recognized elsewhere for its effectiveness and its minimally invasive character.
The objective of this work, which is the first series in West Africa, was to evaluate the feasibility and study the results of PCNL a new therapeutic option in the management of kidney stones.
2. Patients and Methods
We conducted a cross-sectional descriptive study from January 2015 to January 2019, at the urology department of HOGIP. All patients who underwent PCNL treatment at HOGIP during the study period, and who had an available and duly completed medical record, operative report and anesthesia form, were included in our work.
The different variables studied were: marital status, medical and surgical history, circumstances of diagnosis, physical exam findings, imaging exams, location, size and density of the stones, preoperative laboratory assessment, operative modalities and postoperative data. Our data sources were the patients’ medical records, the operative report book and the hospitalization register.
We performed analyses of means, standard deviations and medians for quantitative variables; qualitative variables were studied in terms of frequencies. Statistical significance was accepted for µ < 0.05. Descriptive analyses were performed using Epi Info 7 software.
The surgical procedures were performed under general anesthesia with antibiotic prophylaxis. Patients were positioned either prone, modified supine or modified lateral decubitus. A ureteral catheterization with the injection of contrast reagent mixed with methylene blue was performed at the first stage of the operation. Then a calyceal puncture was performed under fluoroscopic or ultrasound control in the calyx defined preoperatively according to the position of the stone and its complexity. Once the puncture was successful (methylene blue was released through the puncture mandrel), a guide was put in place. A dilatation of the pathway was performed until the amplatz sheath was placed, which allowed access to the calyceal cavities through the nephroscope. The endo-renal lithotripsy used was laser, lithoclast or ultrasound. The drainage used was the double J(JJ) stent, ureteral stent, nephrostomy or drainage through the natural channels (Totally tubeless). The patient was evaluated postoperatively according to the stone free percentage rate, the control of biology and bacteriology and the rate of complications.
3. Results
Among 90 cases operated, the inclusion criteria allowed us to consider 82 cases or 91.11% for our study, and to exclude 8 cases or 8.89%. The average age of our patients was 45.95 years (Range: 16; 80 years). The age group [40 - 49] represented 28.05% of the patients (Table 1). Sex ratio was 1.15.
Regarding patients’ history, 4 patients (4.88%) had hyperparathyroidism while 7 had obstructive uropathy corresponding to 4 cases of pyeloureteral junction syndrome and 3 cases of ureteral stenosis.
Twelve patients had a history of open renal surgery (11 cases of nephrolithotomy and one case of pyelolithotomy).
Atypical back pain was present in 55 cases (45.83%) and renal colic in 32 cases (26.66%).
In our study, lumbar fossa tenderness was observed in 43 cases while 2 cases of large kidneys were outlined on physical examination.
Uro-CT-Scan was performed in all our patients to assess the different characteristics of the stones. Table 2 shows the distribution according to the location of the stones. The predominant sites were renal pelvis in 39 cases (31.2%) and inferior calyx in 34 cases (27.2%). Forty-three patients had two different stone locations in the kidney.
The size was specified in 76% of the stones. A size of 15 - 20 mm was observed in 29 cases (30.52%) and a size of over 20 mm was noted in 24 cases (25.26%) (Table 3).
The density was specified in 48.8% of the calculi (Table 4). A density of 500 - 1000 Hounsfield Unit (HU) was noted in 47.54% of the stones, while a density of 1000 - 1500 HU was noted in 42.62% of the stones.
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Table 1. Age distribution of 82 patients treated with PCNL for urinary lithiasis at HOGIP.
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Table 2. Distribution of stone location on CT-Scan in 82 patients treated with PCNL for urinary lithiasis at HOGIP.
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Table 3. Size distribution of stones in 82 patients treated with PCNL for urinary lithiasis at HOGIP.
Preoperative laboratory workup showed a mean creatinine level of 9.8 mg/l (SD: 2.46; Range: 6.1; 17.4); a mean hemoglobin level of 13.15 g/dl (SD: 1.8; Range: 9.3; 18.3). All patients had sterile urine at urine culture.
General anesthesia with orotracheal intubation was performed in all our patients.
Patients were placed in modified lateral decubitus in 34 cases (41.46%), prone position in 26 cases (31.70%) and supine position in 22 cases (26.84%) (Figure 1).
In 87.8% of the cases, only one access was needed for the entire PNLC procedure and in 10.97% of the cases, two accesses were performed.
Regarding energy source of lithotripsy, lithoclast was used in 54 cases (65.85%), Holmium laser in 24 cases (29.27%) and ultrasound in 4 cases (4.88%).
The overall success rate (stone free) in our series was 96%.
Nephrostomy was performed in 20 cases (32.92%) and the JJ stent in 17 cases (20.73%). It should be noted that in 34 cases (41.44%) no drainage was performed (Figure 2).
Post-operatively, the mean creatinine level was 9.62 mg/l (Range: 5; 8.7). The mean hemoglobin level was 11.32 g/dl (Range: 6.4; 16.9). The median hemoglobin level was 12.2 g/dl.
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Table 4. Distribution of stones according to density (HU) in 82 patients treated with PCNL for urinary lithiasis at HOGIP.
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Figure 1. Distribution of type of patient’s position in 82 patients treated with PCNL for urolithiasis at HOGIP.
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Figure 2. Distribution of type of drainage in 82 patients treated by PCNL for urinary lithiasis at HOGIP.
The urine culture control was positive in 10% of cases in our series.
Ten patients (12.19%) had complications, including 2 cases of intraoperative bleeding, 5 cases of acute pyelonephritis and 1 case of renal colic. Bleeding was noted at the puncture site, sometimes requiring a change in the drainage method into a nephrostomy. No transfusions were performed.
4. Discussion
Endourological treatment of kidney stones, regardless of the technique used, is currently recommended due to its excellent results and acceptable morbidity [9] . Thus, PCNL has a significant place in kidney stone management. It is currently performed routinely in the urology department of HOGIP.
The average age of our patients was 45.95 years (Range: 16; 80 years). The age group [40 - 49] was the most affected (28.05%). Li Jianxing et al. [10] reported a mean age of 43 years (Range: 6 months; 85 years) and Niang et al. [11] noted a mean age of 44.7 ± 13.9 years while Hosseini K et al. [12] reported a relatively younger mean age of 30.3 ± 6.5 years. In contrast, Palmero X et al. [9] reported a higher mean age of 50.7 ± 16.9 years.
Male predominance was noted in our series with a sex ratio of 1.15. In the series by Benchkroun A et al. [8] , the sex ratio was four men to three women (113 men and 85 women).
In our series, we noted the history of 11 cases of open nephrolithotomy and 1 case of pyelolithotomy in the surgical history.
According to the second international consultation on urolithiasis held in Paris in September 2007 [13] , the following recommendation was made: a history of open surgery does not contraindicate PCNL (Level of evidence III). Patients with a history of open nephrolithotomy who are treated with PCNL will, according to Margel et al. [14] , undergo longer operative times (203 ± 92 minutes versus 177 ± 52 minutes) with greater need for an additional procedure (29% versus 12%), but with no loss of efficacy or additional morbidity. However, these differences were not shown by Lojanapiwat et al. [15] .
Uro-CT-Scan was performed in all our patients. It allowed us to determine the different characteristics of the stones. In our series, the renal pelvis and the inferior calyx were the most represented sites with respectively 31.2% and 27.2% of cases. This order of frequency was noted by many authors in the literature. Benchkroun A. et al. [8] , in their study, showed 79.15% of renal pelvic lithiasis and 7.58% of inferior caliceal lithiasis. In our study, the most common stone size was between 15 and 20 mm, in 30.52% of cases. Calculi larger than 20 mm were found in 25.26% of cases. The results of Palmero X. et al. [9] were similar to our findings with 47.8% of stones between 10 and 20 mm and 45.3% larger than 20 mm. This reflects the preferred indication for PCNL for large stones over 20 mm.
In the standard PCNL technique, the patient was installed in the prone position as described by Theocharis K et al. [16] . In our study, the prone position was used in 31.7% of cases. It should be noted that this installation has some disadvantages, namely the change of position after the placement of the ureteral catheter and the respiratory and circulatory anesthetic difficulties, especially in obese patients. However, it reduces the risk of injuries such as perforations of the abdominal viscera, as reported in the studies by Tea-Kon et al. [17] and Theocharis et al. [16] . Although rare, colonic perforation has been reported in 0.2% - 0.3% by Sitki U et al. [18] .
Many types of precautions have been developed subsequently. Modified supine and modified lateral decubitus positions were reported in 26.82% and 41.46% of cases respectively in our study. These positions allow simultaneous anterograde and retrograde access to the calyces, allowing placement of the ureteral catheter and the PCNL itself. Youness El Harrech et al. [19] reported 159 modified supine PCNL in their study.
Yanbo W et al. [20] compared the efficacy and safety of prone and modified supine positions in a study in China. They showed that both positions were effective and safe for PCNL but the operative time was longer in the prone position (78 vs 88 min, P < 0.05). A randomized controlled study by Marco de Seo et al. [21] reported a significant time difference between the two positions (43 min in lateral decubitus versus 68 min in ventral decubitus).
In our study, 87.8% of patients had only one access. The puncture was performed in the lumbar region limited by the posterior axillary line, the 12th rib and the iliac crest. Neto et al. [22] reported that a puncture on the posterior axillary line is safe, even for a supra-costal puncture, whereas in the prone position, a puncture is performed 1 to 2 cm below this line, which increases the risk of perforation of neighboring organs. Fan et al. [23] demonstrated the advantages of the subcostal route compared to the supra-costal route in terms of time-saving for the placement of the puncture trocar, stone extraction and mobility of the Amplatz sheath. It should be noted that guided punctures can be performed by a urologist or a radiologist. In our study, all punctures were performed by a urologist. Watterson et al. [24] showed that if the puncture was performed by a urologist, there were fewer complications and a better fragment-free result. On the other hand, El-Assmy et al. [25] , in a comparative study of 661 punctures performed by a urologist and 612 by a radiologist, found no difference in either complications or outcome.
The treatment of calculi is carried out by endo-corporeal lithotripsy as described by Osman et al. [26] using ultrasound, pneumatic energy or laser fiber. In our study, lithoclast was used in 65.85% of cases and holmium laser in 29.27% of cases. Jou et al. [27] used the same laser fiber in 349 PCNL performed in 334 patients with a fragment-free result of 83.7%. In 3.7% of PCNL, and particularly in cases of very large stones, a pneumatic lithotripter was used in conjunction with the laser fiber to limit the operating time. In a more recent study, Jou et al. [28] showed that the laser could be used successfully for stones larger than 3 cm with an energy of 3.0 J for a fragment-free rate after PCNL of 61.4%. Recently, Lee et al. [29] compared the holmium laser with the Thulium laser with the latter providing more efficient fragmentation and deeper craters.
In our series, the overall success rate (stone free) was 96%. Three hundred and fifteen patients (156 males, 159 females, aged 13 to 85 years) were treated by PCNL between 1987 and 2002 by the team of Osman et al. [26] . At one month, the fragment-free rate was 96.5%, of which 45.7% were stone free immediately postoperatively, 21.3% became stone free secondarily by spontaneous migration of residual fragments and 23% became stone free by secondary treatment with another PCNL, ESWL or ureterorenoscopy. Benchkroun A. et al. [8] reported a success rate (stone free) of 92%. In contrast, Wickham et al. [30] reported a low success rate of 60%.
Drainage of the upper urinary tract was performed by nephrostomy in 32.92% of cases and by JJ stent in 20.73% of cases. It should be noted that in the majority of cases (41.44%), drainage was done by the natural route, also known as totally tubeless. Tubeless PCNL is a PCNL without nephrostomy but with a ureteral stent or a JJ stent. Tubeless PCNL developed by Bellman et al. [31] in 1997 is a valid alternative. A few years after Bellman, Goh and Wolf [32] and Lojanapiwat et al. [15] adopted the principle of not draining the kidney with a nephrostomy tube and proposed replacing the double J stent with a single ureteral tube, which has the advantage of being easily removed.
The overall complication rate in our series was 12.19%, which is comparable to the literature data.
Ballager et al. [33] reported a complication rate of 17.5% for a population of 750 patients.
Complication rate depends essentially on the experience of the operator, the technical platform, anatomical variations (for example retro-renal colon), and the presence of comorbid conditions.
The mortality rate in the literature is 0 to 0.7%, but no deaths were noted in our study. The major complications are hemorrhagic and septic.
Our experience shows that PCNL is an effective technique adapted to our developing country context. Our stone-free rate at the beginning of our practice is already good and could improve further with the increase in the number of cases which will further improve the experience of our team.
However, we noted certain limitations when carrying out this study. We try to list them: the problem of archiving files in our structures; lack of urine analysis before surgical procedures; the lack of means for patients to be able to carry out post-operative control scans.
5. Conclusion
Urinary lithiasis is becoming more and more frequent in our regions. The development of endo-urology offers several therapeutic options. Thus, PCNL occupies an important place in the management of kidney stones. It is being tested in our regions with excellent results and acceptable morbidity and complication rates.
Ethics Approval and Consent to Participate
This study was approved by the ethics committee of Hospital General Idrissa Pouye de Grand Yoff.