Urolithiasis/Endourology Cessation of Ureteral Colic Does Not Necessarily Mean that a Ureteral Stone Has Been Expelled Natalia Hernandez,* Sarah Mozafarpour,* Yan Song and Brian H. Eisner† From the Department of Urology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts Purpose: We evaluated whether cessation of renal colic is consistent with an expelled ureteral stone or whether imaging may be indicated even in the absence of symptoms. Materials and Methods: We performed a retrospective study of patients who presented to our institution with acute renal colic and ureteral stone, and were subsequently evaluated at a followup visit where they reported complete cessa- tion of pain for at least 72 hours. Results: Study inclusion criteria were met by 52 patients, who reported no pain for at least 72 hours at the time of the followup visit. A persistent ureteral stone was demonstrated in 14 of the 52 patients (26%) although they denied any associated symptoms. Multivariate logistic regression did not show an associa- tion between stone size or location and the likelihood of passage in this cohort. Conclusions: Cessation of pain was associated with ureteral stone passage in almost 75% of this study cohort but 26% of patients still had persistent ure- teral stones. We recommend routine followup imaging in all patients with ureteral stones to document stone passage and avoid the risks of silent ure- teral obstruction. Key Words: ureter, ureteral calculi, renal colic, diagnostic imaging, abdominal pain UROLITHIASIS is a worldwide health concern affecting approximately 1 of 11 people in the United States. 1 In patients with acute ureteral obstruc- tion a rapid increase in ureteral pressure results in dilatation of the ureter and renal collecting system, which may cause renal colic. 2,3 The intervention rate of obstructing ure- teral stones varies based on stone size. While stones less than 2 mm pass spontaneously 95% of the time, stones greater than 4 mm pass spon- taneously only 50% of the time with the remaining 50% requiring inter- vention for stone removal. 4 In the absence of a concurrent urinary tract infection or unremitting renal colic current guidelines endorse a trial of spontaneous passage of ureteral stones less than 10 mm with periodic evaluation. 5,6 However, there is currently no consensus on the need for or type of imaging that should be obtained after a trial of spontaneous passage to determine whether a stone remains in the ureter. Furthermore, little data have been published in the literature examining the relationship between stone expulsion and the cession of patient pain. The purpose of the current study was to determine whether resolution of symptoms reported by the patient is sufficient to determine that the patient has passed a ureteral stone or Abbreviation and Acronym KUB ¼ plain x-ray of kidneys, ureters and bladder Accepted for publication October 22, 2017. * Equal study contribution. † Correspondence: Department of Urology, GRB 1102, Massachusetts General Hospital, 55 Fruit St., Boston, Massachusetts 02114 (tele- phone: 617-726-3512; FAX: 617-726-6131; e-mail: [email protected] ). Editor’s Note: This article is the fourth of 5 published in this issue for which category 1 CME credits can be earned. Instructions for obtaining credits are given with the questions on pages 1074 and 1075. 0022-5347/18/1994-1011/0 THE JOURNAL OF UROLOGY ® Ó 2018 by AMERICAN UROLOGICAL ASSOCIATION EDUCATION AND RESEARCH,INC. https://doi.org/10.1016/j.juro.2017.10.032 Vol. 199, 1011-1014, April 2018 Printed in U.S.A. www.jurology.com j 1011 Downloaded for Anonymous User (n/a) at Kaiser Permanente from ClinicalKey.com by Elsevier on April 19, 2018. For personal use only. No other uses without permission. Copyright ©2018. Elsevier Inc. All rights reserved.
Cessation of Ureteral Colic Does Not Necessarily Mean that a Ureteral Stone Has Been Expelled
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Cessation of Ureteral Colic Does Not Necessarily Mean that a Ureteral Stone Has Been ExpelledUrolithiasis/Endourology
Cessation of Ureteral Colic Does Not Necessarily Mean that a Ureteral Stone Has Been Expelled
Natalia Hernandez,* Sarah Mozafarpour,* Yan Song and Brian H. Eisner†
From the Department of Urology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
Abbreviation
GRB 1102, Massachusetts General Hospital, 55 Fruit St., Boston, Massachusetts 02114 (tele- phone: 617-726-3512; FAX: 617-726-6131; e-mail: [email protected]).
Editor’s Note: This article is the fourth of 5 published in this issue for which category 1 CME credits can be earned. Instructions for obtaining credits are given with the questions on pages 1074 and 1075.
Purpose: We evaluated whether cessation of renal colic is consistent with an expelled ureteral stone or whether imaging may be indicated even in the absence of symptoms.
Materials and Methods: We performed a retrospective study of patients who presented to our institution with acute renal colic and ureteral stone, and were subsequently evaluated at a followup visit where they reported complete cessa- tion of pain for at least 72 hours.
Results: Study inclusion criteria were met by 52 patients, who reported no pain for at least 72 hours at the time of the followup visit. A persistent ureteral stone was demonstrated in 14 of the 52 patients (26%) although they denied any associated symptoms. Multivariate logistic regression did not show an associa- tion between stone size or location and the likelihood of passage in this cohort.
Conclusions: Cessation of pain was associated with ureteral stone passage in almost 75% of this study cohort but 26% of patients still had persistent ure- teral stones. We recommend routine followup imaging in all patients with ureteral stones to document stone passage and avoid the risks of silent ure- teral obstruction.
Key Words: ureter, ureteral calculi, renal colic, diagnostic imaging,
abdominal pain
UROLITHIASIS is a worldwide health concern affecting approximately 1 of 11 people in the United States.1 In patients with acute ureteral obstruc- tion a rapid increase in ureteral pressure results in dilatation of the ureter and renal collecting system, which may cause renal colic.2,3 The intervention rate of obstructing ure- teral stones varies based on stone size. While stones less than 2 mm pass spontaneously 95% of the time, stones greater than 4 mm pass spon- taneously only 50% of the time with the remaining 50% requiring inter- vention for stone removal.4 In the absence of a concurrent urinary tract infection or unremitting renal colic
0022-5347/18/1994-1011/0
2018 by AMERICAN UROLOGICAL ASSOCIATION EDUCATION AND RESE
Downloaded for Anonymous User (n/ For personal use only. No other us
current guidelines endorse a trial of spontaneous passage of ureteral stones less than 10 mm with periodic evaluation.5,6 However, there is currently no consensus on the need for or type of imaging that should be obtained after a trial of spontaneous passage to determine whether a stone remains in the ureter. Furthermore, little data have been published in the literature examining the relationship between stone expulsion and the cession of patient pain.
The purpose of the current study was to determine whether resolution of symptoms reported by the patient is sufficient to determine that the patient has passed a ureteral stone or
ARCH, INC.
Printed in U.S.A. www.jurology.com j 1011
a) at Kaiser Permanente from ClinicalKey.com by Elsevier on April 19, 2018. es without permission. Copyright ©2018. Elsevier Inc. All rights reserved.
1012 CESSATION OF URETERAL COLIC
whether additional followup imaging is important to evaluate for a persistent ureteral stone.
No. Pts (%)
Overall 52 Male 38 (73.1) Female 14 (26.9) Hypertension 12 (23.1) Diabetes mellitus 3 (5.8) Nausea 20 (38.5) Vomiting 12 (23.1) Pain: Back 8 (15.4) Abdomen 13 (25) Flank (costovertebral angle) 37 (71.2) Lower quadrant 12 (23.1) Scrotum/labia 7 (13.5)
Hematuria 50 (96.1) Dysuria 12 (15.6) Frequency 4 (5.2) Blood in dipstick 37 (71.1) Leukocyte esterase 6 (11.5) 1st Stone episode 31 (59.6) Stone history: Passage 21 (40.4) Procedure 9 (17.3%)
No patient had gout or evidence of nitrates.
METHODS Institutional review board approval was obtained prior to study initiation. We performed a HIPAA (Health Insur- ance Portability and Accountability Act) compliant, retrospective review of the medical records of patients with acute colic who presented to a tertiary care academic medical center from 2010 to 2014. Study inclusion criteria were 1) imaging evidence of a single ureteral stone at the time of colic in the emergency department, 2) documen- tation of patient symptoms, including whether the patient had been pain free and symptom free for at least 72 hours at the time of the followup appointment, 3) definitive documentation of the presence or absence of a ureteral stone on followup imaging or ureteroscopic evaluation and 4) no patient history report of stone passage via the ure- thra. Patients who presented with multiple or bilateral ureteral stones were excluded from analysis.
Our practice pattern pertains to the patients included in this study. A patient seen in the emergency department with an obstructing ureteral stone and renal colic is typi- cally seen in the urology clinic for followup 3 to 6 weeks after the initial stone event with followup imaging. If the patient has not passed the stone based on followup imag- ing at 6 weeks, the patient is offered observation, shock wave lithotripsy or ureteroscopy based on patient factors and the appropriateness of these treatments. In this retrospective study all patients with persistent ureteral stones elected and consented to ureteroscopy.
Statistical analysis was performed using SPSS, version 22. Baseline variables are described using the mean SD or the percent as appropriate. Multivariate logistic regression analysis was done to examine the as- sociations of stone size and location on the stone presence. Statistical significance was considered at p <0.05.
RESULTS Of the 52 patients who met study inclusion criteria 14 (26.9%) were female and 38 (73.1%) were male. Mean age was 51.2 14.2 years (range 25 to 74). The table lists patient characteristics at the emer- gency department visit. At presentation 26 patients had right ureteral stones while the other half of the patients had left ureteral stones. Some degree of hydronephrosis was noted in 43 patients (82%) while 18% demonstrated no hydronephrosis. Mean axial stone diameter was 4.2 2.2 mm and mean coronal stone diameter was 4.9 2.4 mm. Stone location was in the ureteropelvic junction in 1.9% of cases, the proximal ureter in 28.8%, the distal ure- ter in 28.8% and the ureterovesical junction in 40.4%. Pain scores on a scale of 1 to 10 upon patient admission to the emergency department did not differ between those who did vs did not subse- quently pass stones (mean 7.1 2.7 vs 6.7 3.6,
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p not significant). No patients demonstrated renal forniceal rupture at presentation
Mean time to followup evaluation was 35.8 37.7 days. The followup imaging modality included KUB only in 1.9% of patients, renal ultrasound only in 48.1%, KUB plus renal ultrasound in 13.5% and computerized tomography in 30.8%. Of the 52 patients who met inclusion criteria (ie no pain for greater than 72 hours) 14 (26%) still had stones in the ureter. None of these stones was in a signifi- cantly different location compared to the location at the time of initial imaging. These persistent ure- teral stones were detected by imaging, including KUB in 3 patients, computerized tomography in 9 and ureteroscopic evaluation in 3. Of note, the patients who underwent ureteroscopy were those who refused additional imaging for a variety of reasons. No patient underwent ureteroscopy which failed to reveal a stone. In the remaining 38 of 52 patients (74%) followup imaging showed interval passage of the ureteral stone in question.
At the time of followup microscopic hematuria was present in 50% of the patients who had passed the stone and 16% with persistent ureteral stones (p <0.05). Multivariate logistic regression did not reveal any association of stone size or location with stone passage in our study.
DISCUSSION Renal colic in patients with urolithiasis results from obstruction of the flow of urine when stones become lodged in the ureter.3 Colicky pain is caused by the distension of nerve endings exacerbated by
te from ClinicalKey.com by Elsevier on April 19, 2018. Copyright ©2018. Elsevier Inc. All rights reserved.
CESSATION OF URETERAL COLIC 1013
increases in ureteral pressure. Subsequently rela- tive ischemia of the ureter, activation of the inflammatory cascade and mucosal irritation have also been implicated as sources of pain due to ure- teral obstruction by calculi.2,3,7 However, for rea- sons which to our knowledge are unknown, sometimes stones causing hydronephrosis and ure- teral obstruction fail to cause pain altogether or initially cause pain but then cease to do so. This situation is known as silent obstruction or silent hydronephrosis.8,9
Many clinicians are aware that the rate of spon- taneous ureteral stone passage is based on stone size, that is the smaller the stone, the higher the probability that the stone will pass.4 While stones less than 2 mm require intervention only 5% of the time, those greater than 4 mm require intervention 50% or more of the time.4 The current study is concerned with stones that may potentially cause silent ureteral obstruction. It is aimed at helping clinicians understand the importance of followup imaging in patients with ureteral stones in whom pain has resolved but who did not observe the stone pass via the urethra.
There is no consensus on followup imaging in the patient who presents with a ureteral stone. The joint AUA (American Urological Association)/ Endourological Society guidelines state that “repeat imaging [to evaluate for ureteral stone passage] can include KUB x-ray, renal/bladder ultrasound, or computed tomography.”5,6 A white paper from the AUA describes 2 distinct patients who are treated with observation, including 1 who brings a stone in hand and whose symptoms resolve, requiring no further imaging, and 1 who remains symptomatic with further imaging recommended.10 However, the patient who does not bring a stone in hand but de- nies symptoms is not directly addressed in this white paper.
The purpose of our study was to understand whether the cessation of renal colic that is specif- ically queried about and described during the fol- lowup appointment is consistent with stone passage. We found that cessation of pain for more than 72 hours was associated with stone passage in 74% of patients but 26% of patients still had a ure- teral stone despite reporting complete cessation of pain for more than 3 days.
Why are these data important? Ureteral obstruction is known to cause irreversible renal damage and the presence of symptoms is not a prerequisite for this renal damage.8,9 A study eval- uating patients with known ureteral stones that were not causing symptoms (ie silent ureteral stones) showed that these patients presented with significant renal impairment. In addition, after treatment the stricture rate in patients with silent
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hydronephrosis due to ureteral calculi was 8%, which is significantly higher than what is expected for standard ureteroscopy and may reflect an increased risk of stricture in patients with long- term silent obstruction due to ureteral stones.8
The 52 patients in the current study were seen a mean of 36 days after the initial emergency department presentation with renal colic. They reported at least 72 hours of no symptoms at the time of followup. The 14 patients (26%) with a persistent ureteral stone at that time had silent ureteral stones, similar to those in the study by Marchini et al.8 In our practice to avoid the renal impairment observed by Marchini et al we obtain routine followup imaging 4 to 6 weeks after the initial ureteral stone diagnosis. While our study is small, it suggests that routine imaging is important in the followup of patients with ureteral stones even if patients report absent symptoms at the followup evaluation.
It is interesting to ask why patients would cease to have pain if they have a persistent ureteral stone. The pathophysiology of this phenomenon is unclear and to our knowledge it has not been previously studied systematically. We hypothesize that there are 2 potential mechanisms. 1) As the glomerular filtration rate in the contralateral unobstructed kidney increases with persistent obstruction, perhaps the decrease in outflow from the ipsilateral kidney may lead to a decrease in pain from an obstructing ureteral stone. 2) Perhaps these ure- teral stones resulted in presentation to the emer- gency department because at that time they caused significant ureteral obstruction but subsequent to that they moved to a slightly different position in the ureter. This may have caused less obstruction and, therefore, less pain.
Another interesting finding in this study is the differences in microscopic hematuria at the time of the followup appointment. Somewhat paradoxically 50% of the patients who had passed the stones demonstrated microhematuria but only 16% with persistent stones showed microscopic hematuria. It is well known that patients with a ureteral stone event may have persistent microscopic hematuria for up to several months after the event. It is likely that our small sample size makes it difficult to evaluate the role of microscopic hematuria in pre- dicting stone passage.
Our study has several limitations. It is retro- spective in nature and the cohort number was small at 52 patients. It is possible that with a larger sample size factors that are believed to influence stone passage, such as stone size and location, may become significant predictors, although in our study they were not predictive. Nonetheless, we found that 26% of asymptomatic patients still had
from ClinicalKey.com by Elsevier on April 19, 2018. opyright ©2018. Elsevier Inc. All rights reserved.
1014 CESSATION OF URETERAL COLIC
persistent ureterolithiasis and we think that this is important clinical information for physicians who evaluate patients with ureteral stones. Ureteral wall thickness has recently been discussed as a po- tential predictor of stone impaction but it was not measured in this study.
Hopefully in the future prospective studies will be performed to further understand the natural history of ureteral stones in patients in whom pain completely ceases.
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CONCLUSIONS This small pilot study demonstrates that cessation of pain is not predictive of stone passage in all patients who present with pain and an obstructing ureteral stone. Based on these findings we recommend followup imaging in all patients who do not demonstrate physical evidence of stone passage (ie who do not bring in a stone for anal- ysis or who visualized passage but could not collect the stone).
REFERENCES
1. Scales CD Jr, Smith AC, Hanley JM et al: Prevalence of kidney stones in the United States. Eur Urol 2012; 62: 160.
2. Heid F and Jage J: The treatment of pain in urology. BJU Int 2002; 90: 481.
3. Travaglini F, Bartoletti R, Gacci M et al: Patho- physiology of reno-ureteral colic. Urol Int, suppl., 2004; 72: 20.
4. Miller OF and Kane CJ: Time to stone passage for observed ureteral calculi: a guide for patient education. J Urol 1999; 162: 688.
5. Assimos D, Krambeck A, Miller NL et al: Surgical management of stones: American Urological Association/Endourological Society guideline, part I. J Urol 2016; 196: 1153.
6. Assimos D, Krambeck A, Miller NL et al: Surgical management of stones: American Urological Association/Endourological Society guideline, part II. J Urol 2016; 196: 1161.
7. Cervero F and Sann H: Mechanically evoked re- sponses of afferent fibres innervating the guinea-pig’s ureter: an in vitro study. J Physiol 1989; 412: 245.
te from ClinicalKey.com by E Copyright ©2018. Elsevier In
8. Marchini GS, Vicentini FC, Monga M et al: Irreversible renal function impairment due to silent ureteral stones. Urology 2016; 93: 33.
9. Wimpissinger F, Turk C, Kheyfets O et al: The silence of the stones: asymptomatic ureteral calculi. J Urol 2007; 178: 1341.
10. Fulgham PF, Assimos DG, Pearle MS et al: Clinical Effectiveness Protocols for Imaging in the Management of Ureteral Calculous Disease: AUA Technology Assessment. Linthicum: American Urological Association 2012.
EDITORIAL COMMENT
Urologist: “Did you pass your kidney stone?” calculus on vaginal examination. Urinalysis should
Patient: “Yes.” Urologist: “Did you get an x-ray or actually see
your stone pass?” Patient: “No, but it doesn’t hurt anymoredso I
must have passed my stone.” Silent obstruction. How many times have we as
urologists had this conversation? Finally, there is literature that examines this question: Is the absence of pain sufficient to diagnose passage of a kidney stone? Hernandez et al have answered this question and the verdict is that absence of symp- toms is an unreliable predictor of stone passage, ie up to 26% of patients may have a persistently obstructing stone.
A physical examination should assess for abdominal or back tenderness, which are strong predictors of an obstructing calculus. An astute clinician might detect a ureteral vesical junction
always be performed to look for microhematuria. Ultrasound should be assessed not only for hydro- nephrosis but also for ureteral jets (transvaginal ultrasound increases sensitivity) (reference 9 in article). Any single abnormality of the above merits further evaluation. After decision making with the patient, low dose computerized tomography or diagnostic ureteroscopy is indicated. The failure to diagnose silent obstruction carries risk manage- ment consequences but more importantly perma- nent nephron lossdthe worst case is the tragic loss of a functioning kidney (reference 9 in article).
Roger L. Sur Department of Urology
University of California San Diego Health
San Diego, California
lsevier on April 19, 2018. c. All rights reserved.
Cessation of Ureteral Colic Does Not Necessarily Mean that a Ureteral Stone Has Been Expelled
Methods
Results
Discussion
Conclusions
References
Cessation of Ureteral Colic Does Not Necessarily Mean that a Ureteral Stone Has Been Expelled
Natalia Hernandez,* Sarah Mozafarpour,* Yan Song and Brian H. Eisner†
From the Department of Urology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
Abbreviation
GRB 1102, Massachusetts General Hospital, 55 Fruit St., Boston, Massachusetts 02114 (tele- phone: 617-726-3512; FAX: 617-726-6131; e-mail: [email protected]).
Editor’s Note: This article is the fourth of 5 published in this issue for which category 1 CME credits can be earned. Instructions for obtaining credits are given with the questions on pages 1074 and 1075.
Purpose: We evaluated whether cessation of renal colic is consistent with an expelled ureteral stone or whether imaging may be indicated even in the absence of symptoms.
Materials and Methods: We performed a retrospective study of patients who presented to our institution with acute renal colic and ureteral stone, and were subsequently evaluated at a followup visit where they reported complete cessa- tion of pain for at least 72 hours.
Results: Study inclusion criteria were met by 52 patients, who reported no pain for at least 72 hours at the time of the followup visit. A persistent ureteral stone was demonstrated in 14 of the 52 patients (26%) although they denied any associated symptoms. Multivariate logistic regression did not show an associa- tion between stone size or location and the likelihood of passage in this cohort.
Conclusions: Cessation of pain was associated with ureteral stone passage in almost 75% of this study cohort but 26% of patients still had persistent ure- teral stones. We recommend routine followup imaging in all patients with ureteral stones to document stone passage and avoid the risks of silent ure- teral obstruction.
Key Words: ureter, ureteral calculi, renal colic, diagnostic imaging,
abdominal pain
UROLITHIASIS is a worldwide health concern affecting approximately 1 of 11 people in the United States.1 In patients with acute ureteral obstruc- tion a rapid increase in ureteral pressure results in dilatation of the ureter and renal collecting system, which may cause renal colic.2,3 The intervention rate of obstructing ure- teral stones varies based on stone size. While stones less than 2 mm pass spontaneously 95% of the time, stones greater than 4 mm pass spon- taneously only 50% of the time with the remaining 50% requiring inter- vention for stone removal.4 In the absence of a concurrent urinary tract infection or unremitting renal colic
0022-5347/18/1994-1011/0
2018 by AMERICAN UROLOGICAL ASSOCIATION EDUCATION AND RESE
Downloaded for Anonymous User (n/ For personal use only. No other us
current guidelines endorse a trial of spontaneous passage of ureteral stones less than 10 mm with periodic evaluation.5,6 However, there is currently no consensus on the need for or type of imaging that should be obtained after a trial of spontaneous passage to determine whether a stone remains in the ureter. Furthermore, little data have been published in the literature examining the relationship between stone expulsion and the cession of patient pain.
The purpose of the current study was to determine whether resolution of symptoms reported by the patient is sufficient to determine that the patient has passed a ureteral stone or
ARCH, INC.
Printed in U.S.A. www.jurology.com j 1011
a) at Kaiser Permanente from ClinicalKey.com by Elsevier on April 19, 2018. es without permission. Copyright ©2018. Elsevier Inc. All rights reserved.
1012 CESSATION OF URETERAL COLIC
whether additional followup imaging is important to evaluate for a persistent ureteral stone.
No. Pts (%)
Overall 52 Male 38 (73.1) Female 14 (26.9) Hypertension 12 (23.1) Diabetes mellitus 3 (5.8) Nausea 20 (38.5) Vomiting 12 (23.1) Pain: Back 8 (15.4) Abdomen 13 (25) Flank (costovertebral angle) 37 (71.2) Lower quadrant 12 (23.1) Scrotum/labia 7 (13.5)
Hematuria 50 (96.1) Dysuria 12 (15.6) Frequency 4 (5.2) Blood in dipstick 37 (71.1) Leukocyte esterase 6 (11.5) 1st Stone episode 31 (59.6) Stone history: Passage 21 (40.4) Procedure 9 (17.3%)
No patient had gout or evidence of nitrates.
METHODS Institutional review board approval was obtained prior to study initiation. We performed a HIPAA (Health Insur- ance Portability and Accountability Act) compliant, retrospective review of the medical records of patients with acute colic who presented to a tertiary care academic medical center from 2010 to 2014. Study inclusion criteria were 1) imaging evidence of a single ureteral stone at the time of colic in the emergency department, 2) documen- tation of patient symptoms, including whether the patient had been pain free and symptom free for at least 72 hours at the time of the followup appointment, 3) definitive documentation of the presence or absence of a ureteral stone on followup imaging or ureteroscopic evaluation and 4) no patient history report of stone passage via the ure- thra. Patients who presented with multiple or bilateral ureteral stones were excluded from analysis.
Our practice pattern pertains to the patients included in this study. A patient seen in the emergency department with an obstructing ureteral stone and renal colic is typi- cally seen in the urology clinic for followup 3 to 6 weeks after the initial stone event with followup imaging. If the patient has not passed the stone based on followup imag- ing at 6 weeks, the patient is offered observation, shock wave lithotripsy or ureteroscopy based on patient factors and the appropriateness of these treatments. In this retrospective study all patients with persistent ureteral stones elected and consented to ureteroscopy.
Statistical analysis was performed using SPSS, version 22. Baseline variables are described using the mean SD or the percent as appropriate. Multivariate logistic regression analysis was done to examine the as- sociations of stone size and location on the stone presence. Statistical significance was considered at p <0.05.
RESULTS Of the 52 patients who met study inclusion criteria 14 (26.9%) were female and 38 (73.1%) were male. Mean age was 51.2 14.2 years (range 25 to 74). The table lists patient characteristics at the emer- gency department visit. At presentation 26 patients had right ureteral stones while the other half of the patients had left ureteral stones. Some degree of hydronephrosis was noted in 43 patients (82%) while 18% demonstrated no hydronephrosis. Mean axial stone diameter was 4.2 2.2 mm and mean coronal stone diameter was 4.9 2.4 mm. Stone location was in the ureteropelvic junction in 1.9% of cases, the proximal ureter in 28.8%, the distal ure- ter in 28.8% and the ureterovesical junction in 40.4%. Pain scores on a scale of 1 to 10 upon patient admission to the emergency department did not differ between those who did vs did not subse- quently pass stones (mean 7.1 2.7 vs 6.7 3.6,
Downloaded for Anonymous User (n/a) at Kaiser Permanen For personal use only. No other uses without permission.
p not significant). No patients demonstrated renal forniceal rupture at presentation
Mean time to followup evaluation was 35.8 37.7 days. The followup imaging modality included KUB only in 1.9% of patients, renal ultrasound only in 48.1%, KUB plus renal ultrasound in 13.5% and computerized tomography in 30.8%. Of the 52 patients who met inclusion criteria (ie no pain for greater than 72 hours) 14 (26%) still had stones in the ureter. None of these stones was in a signifi- cantly different location compared to the location at the time of initial imaging. These persistent ure- teral stones were detected by imaging, including KUB in 3 patients, computerized tomography in 9 and ureteroscopic evaluation in 3. Of note, the patients who underwent ureteroscopy were those who refused additional imaging for a variety of reasons. No patient underwent ureteroscopy which failed to reveal a stone. In the remaining 38 of 52 patients (74%) followup imaging showed interval passage of the ureteral stone in question.
At the time of followup microscopic hematuria was present in 50% of the patients who had passed the stone and 16% with persistent ureteral stones (p <0.05). Multivariate logistic regression did not reveal any association of stone size or location with stone passage in our study.
DISCUSSION Renal colic in patients with urolithiasis results from obstruction of the flow of urine when stones become lodged in the ureter.3 Colicky pain is caused by the distension of nerve endings exacerbated by
te from ClinicalKey.com by Elsevier on April 19, 2018. Copyright ©2018. Elsevier Inc. All rights reserved.
CESSATION OF URETERAL COLIC 1013
increases in ureteral pressure. Subsequently rela- tive ischemia of the ureter, activation of the inflammatory cascade and mucosal irritation have also been implicated as sources of pain due to ure- teral obstruction by calculi.2,3,7 However, for rea- sons which to our knowledge are unknown, sometimes stones causing hydronephrosis and ure- teral obstruction fail to cause pain altogether or initially cause pain but then cease to do so. This situation is known as silent obstruction or silent hydronephrosis.8,9
Many clinicians are aware that the rate of spon- taneous ureteral stone passage is based on stone size, that is the smaller the stone, the higher the probability that the stone will pass.4 While stones less than 2 mm require intervention only 5% of the time, those greater than 4 mm require intervention 50% or more of the time.4 The current study is concerned with stones that may potentially cause silent ureteral obstruction. It is aimed at helping clinicians understand the importance of followup imaging in patients with ureteral stones in whom pain has resolved but who did not observe the stone pass via the urethra.
There is no consensus on followup imaging in the patient who presents with a ureteral stone. The joint AUA (American Urological Association)/ Endourological Society guidelines state that “repeat imaging [to evaluate for ureteral stone passage] can include KUB x-ray, renal/bladder ultrasound, or computed tomography.”5,6 A white paper from the AUA describes 2 distinct patients who are treated with observation, including 1 who brings a stone in hand and whose symptoms resolve, requiring no further imaging, and 1 who remains symptomatic with further imaging recommended.10 However, the patient who does not bring a stone in hand but de- nies symptoms is not directly addressed in this white paper.
The purpose of our study was to understand whether the cessation of renal colic that is specif- ically queried about and described during the fol- lowup appointment is consistent with stone passage. We found that cessation of pain for more than 72 hours was associated with stone passage in 74% of patients but 26% of patients still had a ure- teral stone despite reporting complete cessation of pain for more than 3 days.
Why are these data important? Ureteral obstruction is known to cause irreversible renal damage and the presence of symptoms is not a prerequisite for this renal damage.8,9 A study eval- uating patients with known ureteral stones that were not causing symptoms (ie silent ureteral stones) showed that these patients presented with significant renal impairment. In addition, after treatment the stricture rate in patients with silent
Downloaded for Anonymous User (n/a) at Kaiser Permanente For personal use only. No other uses without permission. C
hydronephrosis due to ureteral calculi was 8%, which is significantly higher than what is expected for standard ureteroscopy and may reflect an increased risk of stricture in patients with long- term silent obstruction due to ureteral stones.8
The 52 patients in the current study were seen a mean of 36 days after the initial emergency department presentation with renal colic. They reported at least 72 hours of no symptoms at the time of followup. The 14 patients (26%) with a persistent ureteral stone at that time had silent ureteral stones, similar to those in the study by Marchini et al.8 In our practice to avoid the renal impairment observed by Marchini et al we obtain routine followup imaging 4 to 6 weeks after the initial ureteral stone diagnosis. While our study is small, it suggests that routine imaging is important in the followup of patients with ureteral stones even if patients report absent symptoms at the followup evaluation.
It is interesting to ask why patients would cease to have pain if they have a persistent ureteral stone. The pathophysiology of this phenomenon is unclear and to our knowledge it has not been previously studied systematically. We hypothesize that there are 2 potential mechanisms. 1) As the glomerular filtration rate in the contralateral unobstructed kidney increases with persistent obstruction, perhaps the decrease in outflow from the ipsilateral kidney may lead to a decrease in pain from an obstructing ureteral stone. 2) Perhaps these ure- teral stones resulted in presentation to the emer- gency department because at that time they caused significant ureteral obstruction but subsequent to that they moved to a slightly different position in the ureter. This may have caused less obstruction and, therefore, less pain.
Another interesting finding in this study is the differences in microscopic hematuria at the time of the followup appointment. Somewhat paradoxically 50% of the patients who had passed the stones demonstrated microhematuria but only 16% with persistent stones showed microscopic hematuria. It is well known that patients with a ureteral stone event may have persistent microscopic hematuria for up to several months after the event. It is likely that our small sample size makes it difficult to evaluate the role of microscopic hematuria in pre- dicting stone passage.
Our study has several limitations. It is retro- spective in nature and the cohort number was small at 52 patients. It is possible that with a larger sample size factors that are believed to influence stone passage, such as stone size and location, may become significant predictors, although in our study they were not predictive. Nonetheless, we found that 26% of asymptomatic patients still had
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1014 CESSATION OF URETERAL COLIC
persistent ureterolithiasis and we think that this is important clinical information for physicians who evaluate patients with ureteral stones. Ureteral wall thickness has recently been discussed as a po- tential predictor of stone impaction but it was not measured in this study.
Hopefully in the future prospective studies will be performed to further understand the natural history of ureteral stones in patients in whom pain completely ceases.
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CONCLUSIONS This small pilot study demonstrates that cessation of pain is not predictive of stone passage in all patients who present with pain and an obstructing ureteral stone. Based on these findings we recommend followup imaging in all patients who do not demonstrate physical evidence of stone passage (ie who do not bring in a stone for anal- ysis or who visualized passage but could not collect the stone).
REFERENCES
1. Scales CD Jr, Smith AC, Hanley JM et al: Prevalence of kidney stones in the United States. Eur Urol 2012; 62: 160.
2. Heid F and Jage J: The treatment of pain in urology. BJU Int 2002; 90: 481.
3. Travaglini F, Bartoletti R, Gacci M et al: Patho- physiology of reno-ureteral colic. Urol Int, suppl., 2004; 72: 20.
4. Miller OF and Kane CJ: Time to stone passage for observed ureteral calculi: a guide for patient education. J Urol 1999; 162: 688.
5. Assimos D, Krambeck A, Miller NL et al: Surgical management of stones: American Urological Association/Endourological Society guideline, part I. J Urol 2016; 196: 1153.
6. Assimos D, Krambeck A, Miller NL et al: Surgical management of stones: American Urological Association/Endourological Society guideline, part II. J Urol 2016; 196: 1161.
7. Cervero F and Sann H: Mechanically evoked re- sponses of afferent fibres innervating the guinea-pig’s ureter: an in vitro study. J Physiol 1989; 412: 245.
te from ClinicalKey.com by E Copyright ©2018. Elsevier In
8. Marchini GS, Vicentini FC, Monga M et al: Irreversible renal function impairment due to silent ureteral stones. Urology 2016; 93: 33.
9. Wimpissinger F, Turk C, Kheyfets O et al: The silence of the stones: asymptomatic ureteral calculi. J Urol 2007; 178: 1341.
10. Fulgham PF, Assimos DG, Pearle MS et al: Clinical Effectiveness Protocols for Imaging in the Management of Ureteral Calculous Disease: AUA Technology Assessment. Linthicum: American Urological Association 2012.
EDITORIAL COMMENT
Urologist: “Did you pass your kidney stone?” calculus on vaginal examination. Urinalysis should
Patient: “Yes.” Urologist: “Did you get an x-ray or actually see
your stone pass?” Patient: “No, but it doesn’t hurt anymoredso I
must have passed my stone.” Silent obstruction. How many times have we as
urologists had this conversation? Finally, there is literature that examines this question: Is the absence of pain sufficient to diagnose passage of a kidney stone? Hernandez et al have answered this question and the verdict is that absence of symp- toms is an unreliable predictor of stone passage, ie up to 26% of patients may have a persistently obstructing stone.
A physical examination should assess for abdominal or back tenderness, which are strong predictors of an obstructing calculus. An astute clinician might detect a ureteral vesical junction
always be performed to look for microhematuria. Ultrasound should be assessed not only for hydro- nephrosis but also for ureteral jets (transvaginal ultrasound increases sensitivity) (reference 9 in article). Any single abnormality of the above merits further evaluation. After decision making with the patient, low dose computerized tomography or diagnostic ureteroscopy is indicated. The failure to diagnose silent obstruction carries risk manage- ment consequences but more importantly perma- nent nephron lossdthe worst case is the tragic loss of a functioning kidney (reference 9 in article).
Roger L. Sur Department of Urology
University of California San Diego Health
San Diego, California
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Cessation of Ureteral Colic Does Not Necessarily Mean that a Ureteral Stone Has Been Expelled
Methods
Results
Discussion
Conclusions
References
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