In determining the imaging modality of choice, consideration must be given to the tests‘ accuracy in identifying ureteral stones, the presence of
obstruction, as well as the tests‘ ability to identify diseases that mimic renal colic. In addition,
consideration must be given to the side effects of each test. Five radiographic modalities can be used: CT, ultrasound, IVP, MR, and a plain abdominal x-ray (KUB).
CT
In most centres, a non-contrast helical CT from the top of the kidneys to the bottom of the bladder is the preferred imaging modality. CT is highly sensitive and specific for the detection of renal stones. It is also helpful in determining signs of ureteral obstruction such as ureteral dilatation, perinephric stranding, dilatation of the collecting system, and renal
enlargement. The additional advantage is its superior ability to detect mimickers of renal colic. However, since contrast is not used, it can miss some cases of AAA and appendicitis and will miss most cases of renal infarction or dissection.
The main risk of CT is exposure to a significant amount of ionizing radiation. It should therefore be used judiciously in young patients, and especially in patients with multiple previous presentations of renal colic that have had prior CT studies. It should generally be avoided in pregnancy.
Ultrasound
In contrast to CT, ultrasound has no known side effects. However, it has only modest sensitivity for detecting ureteral stones. Ultrasound is most helpful in diagnosing stones in the proximal and distal ureter but is not sensitive for midureteral stones. It is also less sensitive than CT at detecting mimickers. It is, however, 98% sensitive for detecting hydronephrosis.
MR
MR Urography has poor sensitivity for detecting ureteral stones yet excellent sensitivity in detecting ureteric obstruction. It does not emit any ionizing radiation. However due to its cost, time required, lack of patient monitoring, and limited availability, it is currently rarely used for renal colic.
KUB
Although 90% of urinary calculi are radiopaque, plain abdominal radiographs are neither sensitive nor specific for the detection of nephrolithiasis and should not be used to rule in or rule out a stone. Once a stone has been detected however, the KUB can be used in follow-up to follow its progression.
TREATMENT
Renal Colic is usually an exquisitely painful
condition, and the top management priority should be rapid and adequate analgesia. Parenteral opioid analgesia such as intravenous morphine is the mainstay of treatment. Multiple doses are often necessary. In addition, NSAIDs such as Ibuprofen or
All contents copyright © 2012, University of Toronto. All rights reserved Naproxen (po), or Toradol (IV) should be given
concurrently unless there are contraindications such as peptic ulcer disease, renal impairment, or diabetes. NSAIDs should also usually be avoided in the elderly. To help facilitate passing of the stone, an alpha-blocker such as Tamsulosin (Flomax) 0.4mg once daily for 7-10 days should be prescribed for almost all patients with distal ureteric stones. Patients who are clinically dehydrated should be given an IV of normal saline. Excessive hydration of euvolemic patients should be avoided, as it has not been conclusively shown to aid in stone passage.
DISPOSITION
Absolute indications for urological consultation and admission are:
Intractable pain or vomiting Obstructed stone with infection Single kidney
Transplanted kidney with obstruction
The majority of patients can be discharged from the ED. They should be prescribed an oral opiate as well as an NSAID, and told to return if they develop fever, uncontrolled pain, or vomiting. Appropriate follow- up should be arranged with a urologist or their primary care physician. Urine straining and stone analysis will help with urological follow up in planning prophylactic treatment strategies.
PROGNOSIS
Over 80% of stones will pass spontaneously. In general, smaller stones are most likely to pass spontaneously. If the stone is 4 mm or smaller, they will eventually be passed 90% of the time. Stones 5-7 mm have a 50% chance of passing spontaneously. Stones larger than 7mm are unlikely to pass spontaneously, and should be referred for consideration of lithotripsy. More than half of patients will have a recurrent presentation of renal colic in less than 10 years.
SUMMARY
Renal colic typically presents with severe flank pain radiating to the groin causing the patient to be ‗writhing‘ in pain
The most important and cost effective test in presumed renal colic is a urinalysis
Non-contrast helical CT is the preferred imaging modality for most presentations of renal colic Morphine, NSAIDs, alpha-blockers, and fluid
rehydration are the mainstays of renal colic treatment
Absolute indications for urological consultation and admission are intractable pain or vomiting, obstructed stone with infection, single kidney, and transplanted kidney with obstruction
Most patients with renal colic can be discharged from the emergency department with specific instructions and follow-up
REFERENCES
1. Manthey DE, Nicks BA. Urologic stone disease In: Tintinalli J, et al. editors. Emergency Medicine: A Comprehensive Study Guide - 7th ed. New York: McGraw Hill, 2011:651-656 2. Leslie SW. Nephrolithiasis: Renal Colic In:
Emedicine, May 12, 2006.
3. Manthey DE, Teichman J. Nephrolithiasis. Emergency Medicine Clinics of North America 2001; 19:633-654.
4. Hollingsworth JM. Medical therapy to facilitate urinary stone passage:a meta-analysis. Lancet 2006; 368: 1171-1178.
WHAT‟S NEW
Multiple recent studies have demonstrated that alpha blockers such as Tamsulosin (Flomax) help facilitate the passage of distal ureteric stones. The presumed mechanism of action is related to ureteric smooth muscle relaxation. Based on the mounting evidence, Tamsulosin 0.4 mg per day for approximately 7 – 10 days should be prescribed for virtually all patients with distal ureteric stones.
All contents copyright © 2012, University of Toronto. All rights reserved