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Three Part Question

In [patients with suspected acute renal colic, no fever and normal serum creatinine level], is [bedside ultrasound performed by an emergency physician along with outpatient follow-up or imaging] safe for diagnosis and discharge when compared to [traditional emergency department urinary tree imaging (intravenous pyelograpy or CT-scan)]

Clinical Scenario

A 34 years old man presents to the emergency department at 11:00PM with severe left flank pain and vomiting which began abruptly 4 hours ago. The patient is not known for any health problem nor does he take any medication. He denies fever of chills. You suspect obstructing renal colic. His creatinine level is normal. You administer him NSAIDs and opioid medication, which relieves his pain. You wonder if this patient can safely be discharged at home if your bedside ultrasound is reassuring, with outpatient imaging and follow-up.

Search Strategy

The search was performed on October 20th, 2013.

MEDLINE (through PubMED)
"Renal Colic/ultrasonography"[Mesh]

EMBASE
renal AND ('colic'/exp OR colic) AND bedside AND ('ultrasound'/exp OR ultrasound)

Search Outcome

No BestBETs review was found on this subject.
No Cochrane review was found on this subject.
www.clinicaltrials.org was searched for an ongoing trial on this topic. 4 trials were found to be relevant on this subject.
MEDLINE: one paper was found to be relevant to the question. One paper cited in this article was also found to be relevant and was included for analysis.
EMBASE: 17 articles were screened for relevance. Of those, 4 papers were found to be relevant to the question.

A total of 6 studies were found to be relevant to the question

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Henderson 1998 USA	Pts between 18 and 65 y.o. presenting with symptoms of ureteral colic. Exclusion: Pregnant patients, allergy to contrast, creatinine > 1.8 mg/dl.	Prospective observational study KUB x-ray, 500 ml bolus of normal saline, BUS and formal IVP study. Positive for nephroureterolithiasis if hydronephrosis on BUS or calcification on KUB	Sensitivity of KUB + BUS	97,1% (CI = 93.1-100%)	1- Various ultrasound training and experience 2- Gold standard is IVP 3- All degrees of hydronephrosis considered equally positive 4- High sensitivity possibly because of NS bolus prior to exam 5- Low specificity (resolution of colic in the time between BUS and IVP? False positive caused by bolus?) 6- No outcome data on false negative (n=2) patients (delayed nephrograms
			Specificity	58.9% (CI = 43.5-74.3%)
			PPV	80.7%
			NPV	92.0%
Moak 2012 USA	Patients awaiting for CTscan for presumed renal colic. Pregnant patients, younger than 18 y.o., in custody or unable to consent were excluded	Prospective observational Likelihood of acute ureterolithiasis on VAS, based on clinical findings and UA, on BUS and on CTscan Clinically significant change determined to be 20%	Modification of likelihood by more than 20% based on BUS	30.8% of cases (CI = 22.5-40.6%)	1- Majority of physicians evaluating likelihood were residents in training 2- High NPV for stones >= 5 mm only
			Modification of likelihood by more than 20% based on CTscan	51.4% of cases (CI = 41.6-61.1%)
			Sensitivity of BUS compared to CT for any stone	76.3% (CI = 59.4-88.0%)
			Specificity of BUS compared to CT for any stone	78.3% (CI = 66.4-86.9%)
			PPV of BUS compared to CT for any stone	65.9% (CI = 50.0-79.1%)
			NPV of BUS compared to CT for any stone	85.7% (CI = 74.1-92.9%)
			Sensitivity of BUS compared to CT for stones >= 5mm	90.0% (CI = 54.1-99.5%)
			Specificity of BUS compared to CT for stones >= 5mm	63.9% (CI = 53.4-73.2%)
			PPV of BUS compared to CT for stones >= 5mm	20.4% (CI = 10.3-35.8%)
			NPV of BUS compared to CT for stones >= 5mm	98.4% (CI = 90.3-99.9%)
Fox 2013 USA	Adult patients with suspected renal colic. Excluded if empty bladder or TJF =< 3 in 4 minutes.	Prospective pilot study (abstract only). Duplex BUS of the bladder. 4 minutes evaluation of RJF and TFJ. RJF =< 40% of TJF was considered positive for acute renal colic	Sensitivity for acute ureterolithiasis of BUS compared to CTscan	90% (67-99%)	1- Performed by non-clinician research assistants 2- Limited training 3- Small sample (41 pts) 4- Pilot study
			Specificity	67% (41-87%)
			PPV	74% (52-90%)
			NPV	86% (57-98%)
Kartal 2006 Turkey	Adult patients presenting to ED with unilateral flank pain Exclusions: Patients < 14, fever, pregnant, unable to give informed consent	Prospective non-randomized clinical study Urinanalysis for RBC, BUS. Patients discharged home according to algorithm if positive BUS and positive urianalysis and outpatient follow up in urology	+ BUS and + urianalsysis	99/122 (81%) with confirmed stone. All but 3 discharged home w/o adverse event. Others hospitalized for various reasons	1- Patients with negative BUS and positive urinalaysis for RBCs were sent for radiology exam and were not discharged home. However, they seem to be the safest group for outpatient strategy 2- No outcome data on size of stones or need for surgical/rescue therapy for each group 3- Main outcome is rule-in of nephroureterolithiasis rather than rule-out pathology or complex pathology
			– BUS and + urinanalysis	22/24 (92%) with confirmed stone
			– BUS and – urinanalysis	11/27 (41%) with confirmed stone
			+ BUS and – urinanalysis	44/54 (81%) with confirmed stone
			Overall sensitivity of BUS	80.7%
			Overall specificity of BUS	37.2%
Gaspari 2005 USA	Adults presenting with flank pain believed to be consistent with renal colic. Exclusion: Fever, trauma, known current kidney stone, unstable vital signs and inability to provide consent.	Prospective observational study Patients underwent CT scan, BUS and urinalaysis	Sensitivity of BUS for HN	86.8% (CI = 78.9-92.3%)	1- Most BUS performed by only 2 emergency physicians 2- No safety data according to BUS results 3- HN is a surrogate for diagnosis of renal colic
			Specificity	82.4% (CI = 74.1-88.1)

Comment(s)

Most studies are comparing BUS with usual methods of diagnosis (CT scan or IVP). The diagnosis accuracy of the BUS is mainly based on the presence or absence of HN. Only one study (Kartal, 2006) tries to prospectively validate the accuracy and safety of routine laboratory tests plus BUS to rule in diagnosis of renal colic. Sensitivity/specificity/PPV/NPV are used as surrogate endpoints for safety; however a low sensitivity is clinically irrelevant if stones are small or creates no complication for the patient.

Clinical Bottom Line

Diagnosis accuracy of BUS for acute nephroureterolithiasis is highly variable depending on the protocol used and on the training of the operator. Its use appears to be safe to rule in renal colic as the most probable diagnosis and to rule out renal colic caused by a stone likely to necessitate rescue therapy. Various protocols can improve diagnosis accuracy (fluid bolus prior to BUS, KUB x-ray, bladder duplex ultrasound and urinalaysis). Definitive value of BUS for ED diagnosis of renal colic will likely be answered in upcoming clinical trials. Abbreviations CI : Confidence interval (95% unless otherwise specified) KUB : Kidney, ureters and bladder BUS : Bedside ultrasound, performed by emergency physician IVP : Intravenous pyelography VAS : Visual analog scale UA : Urinanalysis NPV : Negative predictive value PPV : Positive predictive value RJF : Relative jet frequency TJF : Total jet frequency US : Ultrasound RBC : Red blood cells ED : Emergency department

References

1. Dalziel, P.J. and V.E. Noble Bedside ultrasound and the assessment of renal colic: a review Emerg Med J 2013. 30(1): p. 3-8.
2. Henderson, S.O., et al. Bedside emergency department ultrasonography plus radiography of the kidneys, ureters, and bladder vs intravenous pyelography in the evaluation of suspected ureteral colic Acad Emerg Med 1998. 5(7): p. 666-71.
3. Moak, J.H., M.S. Lyons, and C.J. Lindsell Bedside renal ultrasound in the evaluation of suspected ureterolithiasis Am J Emerg Med 2012. 30(1): p. 218-21.
4. Fox, J., et al. Bedside urinary bladder duplex ultrasonography for the detection of obstructing ureteral calculi in the emergency department SAEM abstract 2013, p. 299.
5. Kartal, M., et al. Prospective validation of a current algorithm including bedside US performed by emergency physicians for patients with acute flank pain suspected for renal colic Emerg Med J 2006. 23(5): p. 341-4.
6. Gaspari, R.J. and K. Horst Emergency ultrasound and urinalysis in the evaluation of flank pain Acad Emerg Med 2005. 12(12): p. 1180-4.