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Article of the week: Ultrasound guidance can be used safely for renal tract dilatation during percutaneous nephrolithotomy

Every week, the Editor-in-Chief selects an Article of the Week from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an editorial written by a prominent member of the urological community and a visual abstract prepared by a trainee urologist; we invite you to use the comment tools at the bottom of each post to join the conversation. 

If you only have time to read one article this week, we recommend this one. 

Ultrasound guidance can be used safely for renal tract dilatation during percutaneous nephrolithotomy

Manuel Armas-Phan*, David T. Tzou*, David B. Bayne*, Scott V. Wiener*, Marshall L. Stoller* and Thomas Chi*

*Department of Urology, University of California, San Francisco, CA and Division of Urology, University of Arizona, Tucson, AZ, USA

Abstract

Objectives

To compare clinical outcomes in patients who underwent percutaneous nephrolithotomy (PCNL) with renal tract dilatation performed under fluoroscopic guidance vs renal tract dilatation with ultrasound guidance.

Patients and Methods

We conducted a prospective observational cohort study, enrolling successive patients undergoing PCNL between July 2015 and March 2018. Included in this retrospective analysis were cases where the renal puncture was successfully obtained with ultrasound guidance. Cases were then grouped according to whether fluoroscopy was used to guide renal tract dilatation or not. All statistical analyses were performed using Stata version 15.1 including univariate (Fisher’s exact test, Welch’s t‐test) and multivariate analyses (binomial logistic regression, ordinal logistic regression, and linear regression).

Results

A total of 176 patients underwent PCNL with successful ultrasonography‐guided renal puncture, of whom 38 and 138 underwent renal tract dilatation with fluoroscopic vs ultrasound guidance, respectively. There were no statistically significant differences in patient age, gender, body mass index (BMI), preoperative hydronephrosis, stone burden, procedure laterality, number of dilated tracts, and calyceal puncture location between the two groups. Among ultrasound tract dilatations, a higher proportion of patients were placed in the modified dorsal lithotomy position as opposed to prone, and a significantly shorter operating time was observed. Only modified dorsal lithotomy position remained statistically significant after multivariate regression. There were no statistically significant differences in postoperative stone clearance, complication rate, or intra‐operative estimated blood loss. A 5‐unit increase in a patient’s BMI was associated with 30% greater odds of increasingly severe Clavien–Dindo complications. A 5‐mm decrease in the preoperative stone burden was associated with 20% greater odds of stone‐free status. No variables predicted estimated blood loss with statistical significance.

Conclusions

Renal tract dilatation can be safely performed in the absence of fluoroscopic guidance. Compared to using fluoroscopy, the present study demonstrated that ultrasonography‐guided dilatations can be safely performed without higher complication or bleeding rates. This can be done using a variety of surgical positions, and future studies centred on improving dilatation techniques could be of impactful clinical value.

Editorial: Zero‐radiation stone treatment

In this month’s BJUI, Armas‐Phan et al. [1] report on a prospective observational trial of fluoroscopic vs ultrasound (US)‐guided tract dilatation during percutaneous nephrolithotomy (PCNL). A total of 176 patients underwent successful initial US‐only guided puncture; of these patients, 138 had US‐only dilatation, while in 38 fluoroscopy was required. The authors found no difference in patient factors (e.g. age, gender, body mass index [BMI]) or stone factors (hydronephrosis, stone burden, number of tracts or puncture location). On multivariate analysis, US dilatation was more likely to be performed in the modified dorsal lithotomy position (compared to prone), but there was no significant difference in important outcomes such as stone clearance, complication rates or blood loss.

Whilst only reporting on access (and not necessarily dilatation), the Clinical Research Office of the Endourological Society PCNL Global Study shows us that worldwide fluoroscopic access is by far the most common (88.3% of cases) [2] and there are relatively few reports of US‐guided dilatation in the literature. The technique does produce technical challenges as the surgeon needs to confidently identify the depth of the dilators or balloon and be sure of its location relative to calyceal anatomy. Whilst dilating short is not usually a problem as simply re‐dilating can be done, dilating too far carries serious risk of perforation of the pelvicalyceal system and vascular injury. The authors’ described technique does rely on good kidney and guidewire visualisation, and if this is not possible then fluoroscopy is used instead. Thus, even in this series with experts at this technique, 38 (22%) underwent fluoroscopic dilatation after US‐guided puncture, and of the 138 with intended US dilatation, seven (5%) were converted to fluoroscopy. Furthermore, 115 patients never entered this series as they underwent initial fluoroscopic‐guided puncture. Thus, it is important to realise that this is a series of select patients being treated by expert enthusiasts of this technique and fluoroscopy should be available in the operating theatre, as it is not possible to do this technique for all patients. In particular, obesity limits the visualisation under US and the authors have previously shown that renal access drops from 76.9% of normal‐weight patients (BMI <25 kg/m2) to 45.6% for those classified as obese (BMI >30 kg/m2) [3]. An alternative strategy to avoid radiation is to use endoscopic combined intrarenal surgery (ECIRS), as the depth of dilatation can be monitored by direct visualisation via the flexible ureteroscope.

Patients and healthcare professionals are increasingly aware of the risks posed by ionising radiation. Ferrandino et al. [4] analysed radiation exposure of patients presenting with acute stone episodes in an American setting. The mean dose was a staggering 29.7 mSv and 20% of patients received >50 mSV. There is also awareness of risk to the operating staff from endourological procedures and although doses are relatively low [5], these can accumulate during a lifetime of operating, with risks of not only malignancy but also cataract formation [6]. Whilst I am sure we all wear protective lead gowns in the operating theatre, how many people wear lead glasses? A recent study showed that, at typical workload, the annual dose to the lens of the eye was 29 mSv in interventional endourology [7].

As urologists, we should all be aware of these risks and follow the ALARA (As Low As Reasonably Achievable) principals of keeping doses to a minimum. Thus, this paper [1] is particularly welcome and shows zero‐radiation procedures can be safely performed. The authors now attempt this technique for all PCNL procedures and achieve US‐only puncture and dilatation in over half of their patients. Hopefully, this paper will inspire us all to look at reducing or eliminating radiation usage in our stone procedures and this will be good for patients and surgeons alike.

by Matt Bultitude

 

References

  1. Armas‐Phan MTzou DTBayne DB et al. Ultrasound guidance can be used safely for renal tract dilatation during percutaneous nephrolithotomy. BJUI 2019; 125: 284-91
  2. De La Rosette JAssimos DDesai M et al. The Clinical Research Office of the Endourological Society Percutaneous Nephrolithotomy Global Study: indications, complications, and outcomes in 5803 patients. J Endourol 20112511– 7
  3. Usawachintachit MMasic SChang HAllen IChi TUltrasound guidance to assist percutaneous nephrolithotomy reduces radiation exposure in obese patients. Urology 20169832– 8
  4. Ferrandino MNBagrodia APierre SA et al. Radiation exposure in the acute and short‐term management of urolithiasis at 2 academic centers. J Urol 2009181668– 72
  5. Galonnier FTraxer ORosec M et al. Surgical staff radiation protection during fluoroscopy‐guided urologic interventions. J Endourol 201630638– 43
  6. Hartmann JDistler FBaumuller M et al. Risk of radiation‐induced cataracts: investigation of radiation exposure to the eye lens during endourologic procedures. J Endourol 201832897– 903
  7. Hristova‐Popova JZagorska ASaltirov I et al. Risk of radiation exposure to medical staff involved in interventional endourology. Radiat Prot Dosimetry 2015165268– 71

 

 

What’s the Diagnosis?

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This patient was referred with incidental left sided hydronephrosis on ultrasound.

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Rocktober – Keep on rocking #urojc

We celebrated the two-year anniversary of the international urology journal club this month (@iurojc) with record participation. There were over 500 tweets in the 48 hour discussion of this month’s article, published in New England Journal of Medicine on September 18, 2014, Ultrasound versus Computed Tomography for Suspected Nephrolithiasis. It was a true multidisciplinary discussion with nephrologists, EM docs, and study author, radiologist Rebecca Smith-Bindman tweeting.

This was a multi-institutional prospective randomized control study evaluating bedside and radiology ultrasonography versus CT as the first test performed for patients presenting to the ED with flank or abdominal pain. Patients who initially underwent ultrasound could also receive a CT if the provider felt necessary based on clinical presentation and ultrasound findings. In terms of the primary endpoints, authors found no significant difference across the three groups in high-risk diagnoses with complications related to missed or delayed diagnoses. There was significantly less 6-month cumulative radiation exposure in patients assigned to the ultrasonography groups compared to those assigned to CT. Conclusions of this study in the form of a tweet: Get US first #noharmdone #lessradiation.

Conversation first focused on clarifying the main conclusions of this article. Notably, ED physicians were the focus of this study, who care whether the patient will be admitted or sent home. Information about size, location, etc of stones was omitted from the study since the goal was not definitive stone treatment.

Some of the limitations of the study were brought up early on. First of all, obese patients were excluded (men >129 kg and women >113 kg).

Additionally, the definition of being diagnosed with a stone only applied to individuals who reported passing a stone or having a stone surgically removed.

Much of the conversation focused on how this approach may be beneficial in recurrent stone-formers, although at least a KUB likely needed before taking a patient to the OR.

One of the main issues seemed to be the practicality of universally applying the “ultrasound first” approach. Many institutions do not have ultrasound readily available during night or weekend hours.

ER folks disagreed, and thought that point-of-care ultrasound could be easily adopted.

@soph_cash suggested urologists be the ones to perform ultrasound. Although an important skill to learn, the idea was quickly put to rest.

Author Rebecca Smith-Bindman made a brief appearance in support of the evidence in the study.

Coincidentally, the twitter-based nephrology journal club, #nephjc, discussed the same article this month. @hswapnil tweeted a useful chart comparing radiation doses (think about this next time you eat a banana) https://www.xkcd.com/radiation/

Although the conclusions among nephrologists were similar, @uretericbud said it best:

Overall, the consensus seemed to be that the paper presents good evidence for starting with ultrasound in the ED but applying this in all institutions may be difficult. Ultrasound also has limited use for urologists who are focused on stone treatment rather than catastrophic misses. Finally, some concluding thoughts from participants:

Thank you to all the tweeps over the last two years who have provided knowledge, insight, and a healthy dose of comedy to make #urojc such a huge success. Plugging an idea floated by @CanesDavid

This month’s best tweet prize was sponsored by one beautiful thing vintage furniture.

Lastly, here are the symplur analytics for the month.

Ariel Fredrick is a PGY-2 urology resident at Lahey Hospital in Burlington, Massachusetts.

 

Inadvertent ureteric trauma with an indwelling urethral catheter: limitations of ultrasonography in urological diagnosis

We present a 85-year-old man with a suspected diagnosis of urosepsis and a background of a permanent indwelling catheter, which was consequently shown to have been misplaced in his left ureter. This rare phenomenon is associated with a significant diagnostic dilemma resulting in unrecognised damage unless the clinician has a high index of suspicion. Our case highlights the limitation of ultrasonography in determining such a clinical picture and the accuracy of computed tomography in reaching the diagnosis.

Authors: Desai, Devang; Lah, Kevin; Mackenzie, Ian; Gianduzzo, Troy.
Royal Brisbane and Women’s Hospital, Brisbane, Australia
Corresponding Author: Desai, Devang

 

Introduction
Urethral catheterisation is a common procedure used in the management of LUTS.  It is relatively easy to perform and has low risks; however, UTI secondary to an indwelling urinary catheter is an important complication which should be considered.  We present a case that included a diagnostic dilemma in a patient with long-term urethral catheterisations.

Case Report
An 85-year-old man, with a 4-year history of permanent indwelling catheter secondary to BPH, presented at a peripheral hospital with fever, acute confusion and offensive urine.  His history included recurrent UTIs, mild dementia with poor self-care and TURP performed 3 years previously.  On examination, he had a temperature of 39.4 °C and appeared clinically dehydrated with decreased urine output and catheter bypassing.  Physical examination was unremarkable.  Blood results showed acute chronic renal impairment with a creatinine rise from a baseline of 200–454 µmol/L. His white cell count was normal and C-reactive protein was raised to 211 mg/L.  Urine culture revealed  Klebsiella pneumonia, while blood culture grew a coagulase-negative Staphylococcus.  Renal tract ultrasonography showed a mildly dilated left ureter and a bladder containing a collapsed catheter (Fig 1).  CT was ordered for further evaluation.

12-051-Fig-1

Fig. 1 Dilated ureter: ultrasonography was inconclusive in determining the aetiology.

The CT results showed a dilated left ureter with fat stranding up to the level of the pelvis and a focal rounded dilatation measuring 1.95 x 2.15 cm with a locule of air visible adjacent to the catheter tip. These features confirmed that an 18-F catheter had been inadvertently placed in the left ureter (Fig. 2A,B). Upon removal of the catheter, 100 mL of blood-stained fluid was drained. A new catheter was correctly placed and its position confirmed on follow-up CT, which also demonstrated a dilated left ureter containing high-density material consistent with haematoma within the ureter.

12-051-coronal arrow12-051-transverse arrow

Fig. 2 A, Coronal, B, transverse CT demonstrating inadvertent placement of a urinary catheter in the left ureter.

The patient had ongoing haematuria and so was transferred to our tertiary hospital urology unit for possible surgical intervention for a suspected perforated ureter. Fortunately, upon arrival, the haematuria resolved over the course of the subsequent 12 h. No further surgical input was required and the patient was transferred back to the peripheral hospital where his renal function returned to its previous level. Subsequent cystogram showed bilateral grade 4 vesico-ureteric reflux and a suggestion of an ectopic vesico-ureteric junction. This may have accounted for the inadvertent ureteric catheterisation (Fig. 3).

12-051-cystogram_1001_1003

Fig. 3 Follow-up cystogram demonstrating grade 4 bilateral vesico-ureteric reflux and suggestion of ectopic vesico-ureteric junction.

Discussion
Urethral catherisation is a common procedure in the management of lower urinary tract obstruction. Ultrasonography in the present case could not locate the position of the catheter or any causes of obstruction. Only the dilated left ureter was noted. CT was more desirable for its accuracy and non-operator dependency. Moreover, the ability to obtain an expert opinion by electronically sharing CT images was useful. The cystogram suggesting an ectopic vesico-ureteric junction is also notable as a possible contributing factor in this scenario, along with the reflux disease.

There have been four other reported cases of ureteric catheterisation with a urethral catheter in the literature, of all which have been in females [1–4]. These case reports could not explain the cause of the misplacement, but it was postulated that the unorthotopic nature of the anatomy could be the cause in these very rare cases. Interestingly, none of these authors reported the use of ultrasonography as a mode of investigation, but rather an i.v. pyelogram or a cystogram. Perhaps the low sensitivity [5] and operator-dependent nature of ultrasonography in determining an obstruction was the limitation.

References
1. Singh N, Eardley I. An uncommon complication of urethral catheterization. BJU Int 1996; 77:316–7.

2. Kim M, Park K. Unusual complication of urethral catheterization: A case report. J Korean Med Sci 2008; 23: 161–2

3. Kato H. Incorrect positioning of an indwelling urethral catheter in the ureter. Int J Urol 1997; 4: 417–8.

4. Hara N, Koike H, Bilim V, Takahashi K. Placement of a urethral catheter into the ureter: An unexpected complication after retropubic suspension. Int J Urol 2005; 12: 217–9.

5. Rengifo Abbad D, Rodriguez C Caravaca G, Barreales Tolosa L, Villar del Campo MC, Martel Villagran J, Trapero Garcia MA. Diagnostic validity of helical CT compared to ultrasonography in renal-ureteral colic. Archivos Espanoles de Urologia 2010; 63: 139–44.

 

Date added to bjui.org: 11/04/2013

DOI: 10.1002/BJUIw-2012-051-web

 

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