Ultrasound or Fluoroscopy for Percutaneous Nephrolithotomy Access,Is There Really a Difference? A Review of Literature

Abstract

Objective:

To compare whether the outcomes of ultrasound-guided access percutaneous nephrolithotomy (USGA-PCNL) are similar to standard fluoroscopy-guided access percutaneous nephrolithotomy (FGA-PCNL).

Methods:

A review was developed by using the MEDLINE and Scopus databases and following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol. Studies comparing the USGA-PCNL and the FGA-PCNL were included. Case reports, editorials and letters, unpublished studies, posters, and comments abstracts were excluded.

Results:

We found 12 published articles that compared USGA-PCNL and FGA-PCNL. These included six randomized controlled trials, three case–control trials, and three meta-analyses. The overall results showed no difference in the success of percutaneous access, bleeding, blood transfusion, operative time, postoperative complications, or hospital stay.

Conclusion:

The reported data demonstrate that there are no significant differences between the fluoroscopic-guided access PCNL and the ultrasonographic access PCNL. The choice of puncture depends on the surgeon's expertise in a particular technique and the patient and stone characteristics. Both approaches are equally safe and effective in experienced hands. It is important to recall that the use of one technique does not exclude the use of the other, and they can sometimes be complementary to each other.

Introduction

Percutaneous nephrolithotomy (PCNL) is the preferred procedure when treating big stones in endourology. The American Urological Association strongly recommends this approach as the first-line therapy in symptomatic patients with a total renal stone burden >20 mm because of two reasons: the higher stone-free rate (SFR) it offers, and as a less invasive technique when compared with open, laparoscopic, or robotic approaches.¹ The European Association of Urology also stipulates PCNL as a first-line treatment in patients with renal stones >20 mm, and it recommends it as an alternative for stones between 10 and 20 mm.² In addition, it is considered a good option for caliceal diverticular stones.³

The imaging modalities used for renal puncture and to get percutaneous access largely depend on the surgeon. Historically, PCNL has been performed under fluoroscopic guidance (FG).⁴ Although the main disadvantage is the radiation exposure that comes with it,^4
–6 occasionally the visualization may be inadequate, and in some cases contrast-induced nephropathy may occur.⁶ Hence, ultrasonographic guidance (UG), for puncture of the desired calix and tract dilatation, was developed to theoretically overcome these potential disadvantages. Nowadays, a combinant approach using both FG and UG is increasingly being used to overcome a difficult kidney puncture.

Since ultrasound (US) appeared as a new PCNL access modality, there have been numerous studies published in the literature that compare this technique with that of the traditional puncture by fluoroscopy. The aim of this literature review was to evaluate all published studies that compared US vs fluoroscopy for PCNL access and demonstrate whether there is any benefit of one in terms of the surgical and postoperative outcomes.

Materials and Methods

We did a narrative review by using the MEDLINE and Scopus databases with no time period restriction from inception until December 2019.

The keywords used were as follows: “percutaneous nephrolithotomy,” “nephrolithotomy,” “PCNL,” “PNL,” “ultrasonographic,” “ultrasound,” “ultrasound-guided,” “fluoroscopic,” “fluoroscopy,” “kidney stones,” “complications,” and “outcomes.” Boolean operators (AND, OR) were used to refine the search. The references of each included study were also reviewed, and no language restrictions were applied.

Nonhuman studies, case reports, editorials and letters, unpublished studies, posters, and comments were excluded. The analysis was made by a narrative synthesis.

Results

We found 12 published articles that compared UG and FG for PCNL access. These included six randomized controlled trials (RCTs), three case–control trials (CCTs), and three meta-analyses (Table 1).

Table 1.

Ultrasonographic Guidance Versus Fluoroscopic Guidance for Percutaneous Nephrolithotomy Access

Study design	N	Grouping	Age	Stone size (mean)	Access time (mean)	Operating time (mean)	Fluoroscopy time (mean)	Success rate of puncture	Complications	SFR	Post PCNL nephrostomy tube	Retreatment rate
Basiri et al. 2008,⁷ RCT	100	50 USGA	40.7	24 mm	11 minutes	NA	0.69 minutes	94% collecting system, 90% desired calix	10% bleeding, 4% blood transfusion, 2% angiographic embolization	NA	Nephrostomy tube	NA
		50 FGA	41.6	27 mm	5.5 minutes		0.95 minutes	96% collecting system and desired calix			Nephrostomy tube
Falahatkar et al., 2010,⁸ CCT	28	14 USGA	46.5	51.07 mm	NA	88.92 minutes	NA	NA	7.14% blood transfusion, 14.28% fever	78.60%	Tubeless PCNL except with complications	NA
		14 FGA	45.2	41.92 mm		79.28 minutes			21.43% blood transfusion, 7.14% fever	71.40%	Tubeless PCNL except with complications
Karami et al. 2010,⁹ RCT	60	30 USGA	40.8	>2.5 cm	14.5 ± 2.6	44.7 ± 6.4 minutes	NA	100%	6.7% bleeding, 3.3% blood transfusion, 3.3% fever	86.70%	Tubeless PCNL	NA
		30 FGA	39.4		9.4 ± 2.3	34.9 ± 5.1 minutes		100%	3.3% bleeding, 3.3% fever	90.00%	Tubeless PCNL
Agarwal et al., 2011,¹⁰ RCT	224	112 USGA	31	2.8 cm²	1.8 minutes	NA	14.4 seconds	100%	Two points each group had late second postoperative week moderate bleeding treated conservatively	100.00%	Nephrostomy tube	0.00%
		112 FGA	35	2.3 cm²	3.2 minutes		28.6 seconds	100%		100.00%	Nephrostomy tube
Basiri et al., 2013,¹¹ RCT	89	43 USGA	45.7	352 mm²	NA	110.2 minutes	NA	NA	11.6% blood transfusion, 2.32% fever	90.00%	Nephrostomy tube	NA
		46 FGA	44.8	345 cm²		111.3 minutes			19.5% blood transfusion, 15.21% fever	65.20%	Nephrostomy tube
Andonian et al., 2013,¹² CCT	906	453 USGA	50.2	349 mm²	NA	79.3 minutes	NA	99.30%	6% bleeding, 3.8% blood transfusion, 1.3% hydrothorax, 2.9% pelvic perforation	79.80%	Nephrostomy tube >92%	11.00%
		453 FGA	47.9	456.6 mm²		84.6 minutes		97.10%	13% bleeding, 11.1% blood transfusion, 1.4% hydrothorax, 4% pelvic perforation	73.50%	Nephrostomy tube >92%	17.50%
Jagtap et al., 2014,¹³ RCT	64	32 USGA	40.7	2.1 cm	152.9 seconds	50.3 minutes	9 seconds	NA	xClavien I 6.2% (fever, hematuria), xClavien II 3.1% urinary leakage	100.00%	Upon individual case (nephrostomy tube or Double-J stent)	0.00%
		32 FGA	44.5	2.2 cm	144.3 seconds	49.2 minutes	43.8 seconds		xClavien I 9.4%, xClavien II 6.2%	100.00%	Upon individual case (nephrostomy tube or Double-J stent)	0.00%
Ng et al., 2017,¹⁴ CCT	184	72 USGA	55.6	≥1 cm	NA	169 minutes	NA	NA	No statistical differences in terms of bleeding or other complication xClavien	63.70%	Jacque catheter (17.6F) and Double-J stent	16.70%
		112 FGA	52.6			169 minutes				43.70%	Jacque catheter (22F) and Double-J stent	3.20%
Sun et al., 2017,¹⁵ RCT	86	43 USGA	42.9	29.4 mm	NA	108.4 minutes	NA	NA	7% bleeding, 4.7% fever	79.10%	Not specified	NA
		43 FGA	45.1	30.1 mm		113.2 minutes			11.6% bleeding, 4% fever	69.80%	Not specified
Wang et al., 2015,¹⁶ META	3019	1574 USGA	NA	NA	p = 0.06	NA	2.6 minutes longer for FGA compared to USGA	NA	8.4% lower blood transfusion rate (p = 0.0001), lower bleeding (p = 0.03)	86.20%		NA
		1445 FGA							11.80%	81.90%
Liu et al., 2016,¹⁷ META	2979	1527 USGA	NA	NA	p = 0.0001	p = 0.75	NA	p = 0.88	Bleeding and blood transfusion (p = 0.44), fever (p = 0.21)	p = 0.41		NA
		1452 FGA
Yang et al., 2018,¹⁸ META	966	481 USGA	42.3	24.8 mm	p = 0.41	p = 0.48	NA	NA	Lower complication rates (xClavien I, II) p = 0.03	p = 0.79		NA
		485 FGA	41.7	26.5 mm					No statistical differences in terms of bleeding, fever, renal perforation, or xClavien III, IV

N = number of patients; RCT = randomized controlled trial; CCT = clinical control trial; META = meta-analysis; USGA = ultrasound -guided access; FGA = fluoroscopy-guided access; SFR = stone-free rate; NA = not available; x, modified Clavien-Dindo classification system; PCNL = percutaneous nephrolithotomy.

The first RCT published in 2008 by Basiri and colleagues⁷ compared 50 ultrasound-guided access (USGA) vs 50 fluoroscopy-guided access (FGA) for PCNL. The mean age was 40.7 and 41.6 years respectively. The success rate of puncture to the desired calix was 90% for the USGA and 96% for the FGA. The mean size of the stone was 24 mm for the USGA and 27 mm for the FGA. The time for renal puncture and access to the stone was significantly lower in the FGA group. In terms of complications, there was just one pelvic perforation in the USGA group that recovered after a week. In addition, blood transfusion was needed in two patients in the USGA group and one patient in the FGA group, with angiographic embolization needed in one patient for both groups. In general terms, the logistic regression analysis did not demonstrate a significant complication difference between the two groups.

A few years later in 2019, Falahatkar and colleagues⁸ published a CCT in 28 patients. PCNL was performed in 14 cases each by USGA and FGA. The mean ages for the USGA and FGA groups were 46.5 and 45.2 years, respectively. There was no significant difference in operating times (88.9 minutes vs 79.2 minutes), mean stone burden (51 mm vs 41.9 mm), SFR (78.6% vs 71.4%), or other complications between the USGA and FGA groups respectively. The main complications were intraoperative bleeding and fever. Although one patient in the USGA-PCNL and three in the FGA-PCNL needed transfusion, fever occurred in a few patients in both groups who were successfully treated with antibiotics and antipyretics. Renal pelvis perforation and visceral organ trauma were not reported in either group.

The same year, Karami and colleagues⁹ published an RCT with 60 patients. Of them, 30 underwent USGA-PCNL and 30 underwent FGA-PCNL. There was no significant difference in terms of age (40.8 vs 39.4 years old), stone diameter (28.7 mm vs 27.4 mm), number of stones, SFR (86.7% vs 90%), or complications seen in both groups. Intraoperative bleeding was noted in two patients in the USGA group and one patient in the FGA group, whereas fever was noted in one patient for both groups. Besides that, the mean operating time and mean access time were lower in the USGA group (p < 0.05).

In 2011, Agarwal and colleagues¹⁰ reported an RCT on 224 patients, of whom half had USGA-PCNL and half had FGA-PCNL. In this study, there was a significant difference in the mean access time, operation time, and fluoroscopy time exposure, all of which were lower in the USGA group. Likewise, the number of attempts to get to the desire calix was lower in the USGA. The access success and SFR was 100% in both groups. The radiation exposure needed for the track formation was expectedly shorter with the USGA-PCNL, although in some cases they needed to use the fluoroscopy due to difficulties experienced during the surgery. Two patients in each group had minor bleeding treated conservatively, and none of them needed reintervention.

Basiri and colleagues published another RCT about PCNL access 5 years after their previous study.¹¹ This time, they included 89 patients, 43 in the USGA group and 46 in the FGA group. There was a significant difference in the hospital stay, in favor of the USGA group. Seven patients developed fever in the FGA group, whereas only one had fever in the USGA group. There was no difference in outcome noted between them and no major complications were seen.

Andonian and colleagues¹² published their CCT study in 2013, where they prospectively collected data from 3306 patients from the International Clinical Research Office of the Endourological Society (CROES) database. A total of 2853 (86.3%) and 453 (13.7%) patients underwent FGA-PCNL and USGA-PCNL, respectively. A matched sample of 453 patients from each group was taken, including prior treatment, gender, comorbidities, and renal function. Renal abnormalities and stone burden were higher in the FGA group, and the outcomes in terms of complications with bleeding and transfusion were also higher in this group. Further, the operative time with USGA-PCNL was significantly shorter than FGA-PCNL, with significantly shorter retreatment rates with the former (11% vs 17.5%). There were no significant differences in the success rate of puncture, other complications, or SFR. On multivariate analysis, both the sheath size and the number of punctures were related to the bleeding risk. The smaller sheaths (24–26F) were associated with a three times increased risk of hemorrhage, whereas the larger sheaths (27–30F) were associated with a 4.9 times increased risk of hemorrhage.

In 2014, Jagtap and colleagues¹³ published an RCT where 32 patients underwent USGA-PCNL and 32 underwent standard FGA-PCNL. The mean access time to the desired calix and the number of attempts were similar in both groups. The mean fluoroscopy time was significantly lower in the USGA group, although six of them needed to use fluoroscopy to get into the calix. There were no significant differences in the total operative time, postoperative complications, hemoglobin drop, hospital stay, or SFR, which was 100% in both groups. None of the patients needed any reintervention.

Ng and colleagues¹⁴ performed a CCT in 184 patients. A total of 72 patients underwent USGA-PCNL and 112 underwent FGA-PCNL. There were no differences in the duration of surgery, SFR, or intraoperative/postoperative complications according to Clavien-Dindo classification. On univariate analysis, second-look procedures were significantly higher in the FGA-PCNL group, but on the multivariate analysis there was no significant differences between the two study groups.

In 2017, Sun and colleagues¹⁵ performed an RCT of 86 patients, with 43 patients each undergoing USGA-PCNL and FGA-PCNL. The mean age was similar in both groups (42.9 years vs 45.1 years). There was no significant difference in stone diameter, location or number, and the SFR; operating time and complication rates (fever and bleeding) were also similar in both the groups.

Wang and colleagues¹⁶ did a metanalysis comparing both USGA-PCNL and FGA-PCNL for studies published between 2000 and 2014. A total of 14 studies (3019 patients) were included in the final analysis, of which 5 were RCTs with 608 patients and 9 were CCTs with 2411 patients. Of these, 1574 (52%) patients had USGA-PCNL and 1445 (48%) had FGA-PCNL. There were no significant differences in the operative duration for percutaneous access in four RCT and five CCT, nor on length of hospital stay. On the contrary, there was a significant difference in the SFR, complications rate, intraoperative bleeding, and blood transfusion rates. The SFR was higher in the USGA-PCNL group (86.2% vs 81.9%) of the 13 analyzed studies that mentioned these data (5 RCT and 8 CCT). The complication rate was significantly higher for the FGA-PCNL group (11.8% vs 8.4%) in the 12 studies reporting this information (5 RCT and 7 CCT). Five studies reported blood transfusion data (four RCTs and one CCT), and these were also higher in the FGA-PCNL group. Six studies reported on intraoperative blood loss (all the CCT), and it was significantly lower in the USGA-PCNL group.

In 2016, there was another meta-analysis about this subject by Liu and colleagues¹⁷ and they included 18 studies (6 RCT and 12 CCT) with a total of 2919 patients. There was no significant difference in the SFR, operation time, hospital stay, percutaneous access rate (in 11 studies), decrease in hemoglobin, or postoperative pyrexia. The advantages of USGA-PCNL were shorter puncture time, higher success rate of first puncture (in 12 studies), less blood loss, and transfusion requirement. The complications seen were perforation of the renal pelvis in two patients for each group, pneumothorax in five FGA-PCNL patients and two USGA-PCNL patients, and bowel injury in one patient in the fluoroscopy group.

Lastly, in 2018, Yang and colleagues published another meta-analysis where they identified and analyzed eight RCTs comparing USGA-PCNL and FGA-PCNL.¹⁸ Of the 966 patients, 481 (49.8%) had undergone USGA-PCNL and 485 (50.2%) had undergone FGA-PCNL. There were no differences in terms of mean age of the USGA-PCNL and FGA-PCNL (42.3 vs 41.7 years), body mass index (24.8 vs 24.4 kg/m²), or stone size. There was no statistical difference in SFR in seven studies (799 patients), success rate for percutaneous access (six studies), time necessary for entrance into the target calix (six studies), procedural duration (four studies), hospital stay (four studies), transfusion rate (three studies), drop in hemoglobin after surgery (four studies), and auxiliary procedure rate (two studies). No statistical difference was found in both groups when analyzing Clavien grade III and IV complications and neither in reference to intraoperative bleeding, renal pelvis perforation, or postoperative fever. There was only one study conducted by Zhu and colleagues⁴ that mentioned a significantly lower complication rate in the USGA-PCNL group when compared with the FGA-PCNL group; however, none of the other studies showed a difference in this aspect. However, Clavien grades I–II were higher in the FGA-PCNL group.

Discussion

Over the past decade, there has been an improvement in PCNL technique, technology, and equipment needed to perform the procedure.¹⁹ Although percutaneous renal access still remains challenging, each percutaneous technique has advantages and disadvantages and no single technique is ideal in all circumstances; however, US is always complementary to fluoroscopy in difficult cases. It is perhaps advantageous to know both these techniques and determine the best approach that is tailored to an individual patient.

Quality of access

There appears to be no significant difference in the mean access rate^7,10,13 and success rate of puncture^7,10,12 when comparing US or fluroscopy for puncture. Two out of the three meta-analyses included also agreed in this aspect. The other meta-analysis conducted by Liu and colleagues¹⁷ described a shorter puncture time and a higher success rate of first puncture with the help of US. This could reflect the study that was designed in China, where ultrasonography is commonly used in many centers. The competence of US-guided PCNL was described by Song and associates,²⁰ suggesting that 60 cases are needed for the competence to have a high SFR and without major complications, and this also allows a reduction in the screening time and procedural time.

Operating time

The other field of interest is the operating time, which did not show a significant difference on the evaluated trials,^{8,10,11,14,15} nor in the three meta-analyses published. Nevertheless, in three RCTs^9,12,13 there was a significant lower procedural time in the USGA-PCNL group.

Bleeding

In terms of bleeding, there was no significant difference in almost all the studies included in this review that compared USGA-PCNL and FGA-PCNL.

Three studies^8,9,12 mentioned bleeding requiring blood transfusion, with successful recovery of patients. Wang and colleagues¹³ mentioned a higher intraoperative bleeding in the FGA-PCNL group, which they attributed to a bigger diameter access sheath used,^12,21 when compared with the USGA-PCNL group, and also because of the longer operating time in the former group. Nonetheless, after adjusting for sheath size and number of tracts, there was no statistically significant difference between both groups.

Colonic perforation

Of all the studies, just one¹⁸ mentioned bowel injury in the FGA-PCNL group, with a successful recovery. None of the other studies mentioned this in their results.

In a study by El-Nahas and colleagues,²² in 5039 patients who underwent standard FGA-PCNL in one single institution, they concluded that independent risk factors for colonic perforation were advanced patient age and the presence of a horseshoe kidney. Similarly, in a report by Vallancien and colleagues²³ of standard PCNL in 250 patients who had 2 colonic perforations, it was concluded that even after taking all possible precautions, colonic perforation can still occur.

It is important to identify the independent risk factors for colonic perforation, and early diagnosis and proper management are essential for minimizing patient morbidity and avoiding serious implications from this.

Renal pelvis perforation

There seems to be no significant difference in renal pelvis perforation rate between both PCNL approaches, in spite of what is mentioned in the CROES study,¹⁴ that showed a lower incidence of pelvic perforation in the US group (2.9% vs 4%, p = 0.460). By reducing the renal movement, the risk of collecting system perforation can be reduced.¹⁰

Fever

There was no significant difference between the USGA-PCNL and FGA-PCNL groups, and all patients were successfully treated with antibiotics and antipyretics.

Hospital stay

Focusing on the length of hospital stay, there was no significant difference between the USGA-PCNL and FGA-PCNL groups. The average hospital stay was between 2 and 3 days.

Radiation exposure

One of the primary consequences of fluoroscopic-guided PCNL is the radiation exposure. It is well known that in spite of having all the necessary protection to avoid this, there is always an amount of radiation that the physicians and patients receive. The International Commission on Radiation Protection recommends the annual limit of 20 mSv in the lens of the eye, 500 mSv in the skin, and 500 mSv in the extremities.^24,25 However, if possible, even this should be avoided. This is one of the primary advantages of USGA-PCNL.²⁶

In this review, as expected we found a significantly higher mean fluoroscopy time in the FGA group.^7,10,13 One meta-analysis¹⁶ described that the X-ray exposure was 2.6 minutes longer for the FGA group compared with the USGA group. The use of US in endourological procedures is a safe and efficient alternative not just for the pediatric population, with a success rate of 89.2%, but also for adults whether it is in a prone or supine position.²⁷

Success rate of puncture and SFR

The success rate of renal puncture and the SFR are perhaps one of the most important topics to evaluate. The four RCT that we included^7,9,10,12 showed no significant difference in the success rate of puncture. This correlates with a previous report of nephrostomy tube placement success rate published by Montanari and colleagues²⁸ demonstrating that the US- and fluoroscopy PCNL-guided access had a success rate of 98% in both groups. Gupta and colleagues²⁹ published a similar success rate but only studied USGA-PCNL. There were two studies that stated that the fluoroscopy group had a higher rate of multiple tracts compared with the US group. One was by Andonian and colleagues,¹² where they contributed this to lead to slightly more bleeding seen in the FGA-PCNL. The other study, by Agarwal and colleagues,¹⁰ showed that the mean number of attempts required for successful puncture in the desired calix was significantly lower in the USGA-PCNL group. The reason was attributed to the three-dimensional anatomy and visualization of the surrounding viscera that the real-time US gave, which helped the needle-guide to assess the accurate depth and plane of puncture to reach the desired calix.

The SFR did not show any significant difference when comparing both approaches in all but two of the studies selected in this review. The first was the RCT by Basiri and coworkers⁷ that did not mention this aspect, and the second was the meta-analysis by Wang et al.,¹⁶ where the SFR reported was higher in the USGA-PCNL group (86.2% vs 81.9%). Conversely, the most recent meta-analyses published in 2016¹⁷ and 2019¹⁸ did not show any difference in bleeding or SFR between the two techniques.

Conclusion

Our study showed that there is no significant difference between fluoroscopy and US-guided PCNL and both approaches seem to be safe and effective. The choice depends on the surgeon's expertise in a particular technique along with patient and stone characteristics. Nonetheless, in experienced hands managing both these techniques, the performance of US-guided PCNL offers the advantage of a lower radiation exposure. US seems to be supportive of fluoroscopy, especially in difficult cases, although the use of one technique does not exclude the use of other, and they can be used in a complementary fashion.

Footnotes

Disclaimer

This research is a review paper and does not involve research in humans or animals.

Authors' Contribution

M.C.: Project development, data collection, and article writing; S.D., Y.B., and H.K.: Data analysis; O.T., B.S.: Project development, data collection, and article editing.

Author Disclosure Statement

Prof. O.T. is a consultant for Coloplast, Rocamed, Olympus, EMS, Boston Scientific, and IPG. No competing financial interests exist.

Funding Information

No funding was received for this article.

Abbreviations Used

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