Non-Angled Intercostal Percutaneous Access Under Full Expiration: Safety Is Not an Issue Anymore

Introduction

Percutaneous nephrolithotomy (PCNL) is a well-established procedure for the management of urinary stone disease. The initial step in any effective PCNL is the accurate creation of a nephrostomy tract that allows direct access for better stone handling. Straight access to the tip of the appropriate calix is a critical technique that conveys to the ease of the procedure and attains higher stone clearance rates. Frequently, the renal anatomy favors an approach through the upper pole. ¹ Stone burden and location are another two important factors that influence the approach preference of most urologists. ^1,2 Access through the upper pole provides ideal alignment with most of the renal collecting system and provides direct visualization of the upper ureter. The indications for upper pole access are staghorn calculi, large upper caliceal calculi, calculi associated with ureteropelvic junction (UPJ) pathology, calculi in anomalous kidneys, and large upper-ureteral calculi. ^2,3 Upper pole access can be achieved using both intercostal or subcostal approaches. Occasionally, the optimal angle of entry is best accomplished by a puncture above the costal margin. Nevertheless, intercostal approach remains disputable among various urologists and is still a major concern because of its potential complications. ⁴

The objective of this study is to demonstrate that intercostal access through the upper pole can be realized in a safe way to provide optimal approach to the intrarenal collecting system and allow less angulation and less bleeding and yield higher stone clearance rates with a near-normal frequency of complications.

Materials and Methods

The study population consisted of 361 patients, 67.1% males and 32.9% females, mean age 49.27 years, who underwent PCNL surgery from 2010 to 2015 at Saint George Hospital University Medical Center in Beirut, Lebanon. A single operator conducted all the PCNL procedures. The indications for PCNL used were staghorn calculi, a stone burden greater than 2 cm in the upper pole or greater than 1.5 cm in the lower pole, extracorporeal shockwave lithotripsy or flexible ureterorenoscopic treatment failures, or for the treatment of concurrent intrarenal pathology such as UPJ obstruction. ⁵ Patients with a history of open nephrolithotomy, those who underwent a redo PCNL, those requiring two or more access tracts, those with missing data, and those who underwent a two-step PCNL procedure with nephrostomies performed by an interventional radiologist were excluded from this study. A retrospective review of the remaining 304 patients was performed. Patient characteristics, stone burden and location, preoperative and postoperative hemoglobin, location of the access tract, puncture site, operative and hospitalization time, postoperative kidney, ureter, and bladder radiograph (KUB), opioid use, and complications were recorded.

We herein describe the surgical technique used to access the targeted calix (Fig. 1). Under general anesthesia, the patient is placed in lithotomy position, and a 6F open-end ureteral catheter is advanced in a retrograde manner into the renal pelvis allowing the injection of contrast to opacify the collecting system. Patient is then placed in prone position, and the C-arm fluoroscopy is placed in an anteroposterior position. The collecting system is opacified by retrograde infusion of nonionic contrast medium through the open-end catheter. Using the bull's eye technique, the designated calix is determined intraoperatively, and the decision regarding the site of skin incision and angle of puncture is made. The C-arm fluoroscopy is rotated 30° toward the surgeon and placed in a lateral position. An 18G diamond-tip needle is held over the targeted calix, and the direction of the needle is confirmed after obtaining a bull's eye fluoroscopic image. With the help of the anesthesiologist, respiration is suspended at full expiration while the needle is advanced until it reaches the pelvicaliceal system. The C-arm fluoroscopy is then medially rotated to a vertical position (90°), and the needle is further delicately advanced until reaching the desired renal calix. The above-designated step is essentially used to assess the depth of the collecting system. Needle position in the pelvicaliceal system is next confirmed by either urine aspiration or by injecting methylene blue through the open-end catheter and detecting the efflux of material from the needle. A sensor guidewire (0.35F) is thenceforth properly advanced within the pelvicaliceal system. Subsequently, a 10F fascial dilator is placed over the guidewire to dilate the tract. High-pressure balloon NephroMax^® (Boston Scientific) is then used for a one-step dilatation to 30F. Amplatz sheath (30F) is pushed forward over the inflated balloon into the determined calix. The Amplatz sheath serves as a tamponade and to evacuate the flush solutions. ⁴ Moreover, a rigid nephroscope (24F) is introduced so the collecting system is visually examined, and the open-end catheter is identified and pulled through the Amplatz sheath. A through-and-through safety guidewire is next antegradely inserted through the open-end catheter. Afterward, the calculus is identified and, if the stone is too large to be removed, it is fragmented using a lithotripter. All fragments are then retrieved using suction or stone grasper. Irrigation with isotonic solution is further used to remove all stone debris. Successively, a thorough visual and fluoroscopic inspection is performed to ensure a stone-free status. Under fluoroscopic guidance, a double lumen catheter is then placed over the safety guidewire, and another guidewire is then introduced and advanced until it reaches the bladder. Depending on the patient's height, a 6F 26 cm or 6F 28 cm Double-J ureteral stent is placed next in an antegrade manner. Nephrostomy tube (22F) is finally placed draining the kidney into a collecting bag.

OPEN IN VIEWER

FIG. 1.

X-ray images of a patient's renal unit. (A) Preoperative KUB showing right staghorn calculi involving all calices. (B) Preoperative KUB showing right staghorn calculi involving all calices. (C) Oblique image of access needle targeting right upper pole calix. (D) Upper pole access established and guidewire pushed down the ureteropelvic junction. (E) One-step balloon dilation and Amplatz sheath advanced into the upper pole. (F) Stone free after a single percutaneous access. KUB = kidney, ureter, and bladder radiograph.

To rule out any possible pneumothorax complications, a postoperative Chest X-ray is performed routinely and twice on every patient: First in the recovery room and next the following day. In addition, a plain KUB is performed on the first postoperative day to document stone clearance. Patients with no calcifications or with residual stones <4 mm are considered stone free and usually do not require further treatment. The nephrostomy is finally clamped and removed if the postoperative film was satisfactory.

Statistical Analysis

Data were collected from electronic medical records and operative reports at our institution. Data analysis was conducted using Stata/IC 10.0. Bivariate analysis was conducted using Pearson's Chi-square, and logistic regression model was run. The critical alpha level was set at 0.05.

Results

Percutaneous access was performed in 284 cases (93.42%) for stone removal, in 8 cases (2.63%) for Endopyelotomy, in 10 cases (3.29%) for Endopyelotomy and stone removal, in 1 case (0.33%) for a retained Double-J ureteral stent removal, and in 1 case (0.33%) for intrarenal tumor resection. One hundred fifty-five of the patients (50.98%) underwent at least one prior treatment modality; 121 patients (39.8%) had no previous treatment, while 28 patients (9.21%) remained unknown. History of stones was present in 163 patients (53.62%), 115 patients (37.83%) had no known history, and 26 patients (8.55%) were undetermined (Table 1). The average stone surface area was 9.02 cm², and the stone locations were distributed as follows: 118 cases of Staghorn calculi (40.13%), 32 cases of multiple calculi (10.88%), 20 cases of upper pole calculi (6.80%), 10 cases of interpolar calculi (3.40%), 59 cases of lower pole calculi (20.1%), 38 cases of pelvic calculi (12.92%), and 17 cases of impacted UPJ or upper ureteral calculi (5.78%).

A total of 166 (54.61%) access tracts were intercostal (Group I) and 138 (45.39%) were subcostal (Group II). The mean ages of Groups I and II were 48.53 and 49.57 years, respectively. In Group I, 101 (60.84%) patients were males, while 65 (39.16%) were females. In contrast, 74.64% (103) of the patients in Group II were males vs 25.36% (35) females. The average BMI of the intercostal and subcostal groups was 28.60 ± 6.48 kg/m² and 28.73 ± 5.01 kg/m², respectively. The average stone surface area was 9.18 ± 7.66 cm² in Group I vs 8.83 ± 8.26 cm² in the subcostal group.

In the intercostal access group 87 (52.41%) of the punctures were in the upper pole calix, 70 (42.17%) were in the interpolar calix, and 9 (5.42%) were in the lower pole calix. On the contrary in Group II, 2 (1.45%) of the puncture sites were in the upper pole calix, 11 (7.97%) were in the interpolar calix, and 125 (90.58%) in the lower pole calix (Table 2). Staghorn calculi were accessed 59.32% of the time through intercostal access with the upper pole calix being an evident preference (33.9%). Similarly, the upper pole calix was favored in the management of 58.82% of the UPJ impacted or upper ureteral stones. In contrast, subcostal lower pole calix access was selected for 88.13% of inferior lobe calculi.

The average drop in hemoglobin in Group II was 1.9 ± 1.2 g/dL compared to 1.48 ± 1.11 g/dL in Group I (p-value = 0.0040). Moreover, 97.50% of Group I and 94.93% of Group II did not require any blood transfusion.

The mean average operation time in the intercostal group is 88.61 ± 37.13 minutes, which is lower than the mean average time of the subcostal group at 102.58 ± 51.06 minutes. In addition, a total of 38 (22.89%) patients of the intercostal group required opioids for postoperative pain relief while 27 (19.57%) only in the subcostal group (Table 3).

Regarding the postoperative KUB, we considered patients with stone-free X-ray results and those with residual stones of <4 mm as clinically stone free. Patients were stone free in 88.05% and 78.52% of the cases in the intercostal and subcostal groups, respectively. Moreover, Group II patients were twice more likely to have residual stones >4 mm compared to Group I (p-value = 0.029). In Group I cases, 7.83% required further secondary procedures for management of residual stones vs 11.59% in Group II (Table 4).

Patients undergoing PCNL at our institutions are usually admitted on early morning of the same day of operation. The average hospitalization stay for the intercostal and the subcostal groups was 2.24 and 2.43 days, respectively. Complications were recorded according to modified Clavien classification system (Table 5). A total of 31 out of 304 patients (10.2%) with complications were described in both groups. Grade I complications were reported in 7 (2.28%) patients, Grade II in 21 (6.90%), and Grade IIIb in 3 (0.98%). There were no Grade IV or Grade V complications. No cases of pneumothorax were reported in any of the two groups. Overall complication rate was 7.83% in Group I and 13.04% in Group II. Although the complication rate was higher in Group II, the difference was not statistically significant (p-value >0.05).

Discussion

Since its early introduction in the late 1970s, notable advancements have been achieved in the field of percutaneous renal surgeries. The idea of percutaneous approach was initially introduced to effectively manage nephrolithiasis in a minimally invasive technique and with acceptable complication rates. ⁵ As mentioned earlier, an upper pole calix access provides a direct trajectory along the kidney axis and comes to terms with the best understanding of the intrarenal anatomy. ⁶ Entry through the upper pole calix allows convenient maneuvering with the rigid nephroscope along the normal axis of the kidney with minimal angulation and, consequently, lesser bleeding. ⁷ In the article entitle, “Angular Percutaneous Renal Access,” Liatsikos et al. ⁸ described the subcostal triangulation technique they adapted to reach the upper pole calix. Using this technique, an average blood transfusion rate of 45% and an average length of hospital stay of 4.6 days were reported. The overall rate of complications was 24%. ⁸ In contrast, our results show a significantly low transfusion rate (7.47%), an overall complications rate of 10.2%, and a shorter average hospital stay. These findings can be explained with the better exposure to all calices in the intercostal access. The direct access to the posterior upper pole calix offers a short and straight trajectory to the renal pelvis and the upper ureter. ^{6 –8} Using intercostal nontilted direct access, the tip of the desired calix can be reached without applying significant torque or angulation and without violating the interlobar vessels. ^2,7,8

In our series, the operative time was significantly less in the intercostal approach compared to the subcostal access (p-value: 0.0064). Moreover, Group II patients were twice more likely to have residual stones >4 mm compared to Group I (p-value = 0.029). In addition, patients who underwent PCNL using the intercostal approach required less secondary procedures. The opportunity to straightly advance the Amplatz sheath from the upper pole into the renal pelvis, the upper ureter, and lower pole provides urologists with the greatest visibility of the operative field and minimizes the risk of renal tissue laceration especially when using a rigid nephroscope. ^{2,6 –8} McAllister and colleagues explained that an injury to the intercostal artery is a potential mechanism of the increased risk of bleeding and transfusions after intercostal PCNL. ⁹ Therefore, they recommended that placing the access tract immediately lateral to the paraspinal muscles and in the lower half of the 11th intercostal space, but at least 5 mm above the 12th rib, decreases the potential for pain, bleeding, and need for transfusion. ^9,10,11 Similarly, every necessary precaution is taken to avoid direct puncture into the pelvis or near the infundibulum. According to Sampaio et al. injury to an interlobar vessel was seen in 67% of punctures to the upper pole infundibulum; however, no arterial injury was detected when the puncture was made through the center of the caliceal papilla. ^7,12 Our data revealed that postoperative bleeding was significantly less in Group I with a minimal rate of blood transfusion. With decreased capability for maneuver using rigid nephroscope, severe injury to the interlobar vessels might occur if angulation of the tract is used to reach the stone-bearing area. ^{6 –8,12} Such drawback can be avoided when using direct intercostal approach.

In most patients, a trajectory to the posterior upper pole calix through the intercostal space is possible without breaching the pleural space and can be accomplished when it is accessed during full expiration. ¹³ It is essential to understand the anatomy of the kidney in relation to diaphragm, the pleura, and the lung to achieve a safe puncture and avoid complications. ^10,13 In the midscapular line, the parietal pleura inserts at the level of the 12th rib medially. The lateral half of the 12th rib lies below the parietal pleura as it courses superiorly. Therefore, Raza and colleagues deduce that by staying above the lateral half of the 12th rib, an injury to the pleura can be avoided. ¹⁰ Our data reveal no significant difference in the complication rate between both groups. Using the standardized technique previously described, no cases of pneumothorax were reported.

This retrospective study of a series of PCNL procedures performed by one operator is subject to bias. The learning curve of a single surgeon progresses with time, practice, and experience. This may lead to an increase in the success rate and fewer complications. Second, in our study the drop in hemoglobin was used to assess the superiority of intercostal vs subcostal approaches. Puncture site is the most imperative cause of postoperative bleeding in PCNL, but not the only one. Turna and colleagues state that staghorn stones, multiple tracts, history of diabetes, and large stone burden are significantly associated with increased renal hemorrhage. ¹⁴ Third, due to the retrospective nature of our data, the difference between the 11th intercostal space approach, which is anatomically transthoracic but extrapleural, and the high 10th intercostal space access, which is anatomically both transthoracic and transpleural, was not addressed. This raises questions that may be used as hypotheses for further research.

Conclusions

Our findings show that compared to subcostal access, intercostal approach is relatively a safe technique that provides optimal approach to the intrarenal collecting system and allows less angulation and less bleeding and yields higher stone clearance rates with a near-normal frequency of complications. Under full expiration, intercostal access could be advocated in PCNL to obtain a direct non-angled access to the tip of the desired posterior calix.