1. What is your preferred pain regimen in acute renal colic? What do you like to give for home pain control?
Many consider NSAIDs to be first-line for renal colic pain, as they directly affect the ureter, inhibiting the synthesis of prostaglandins. A prospective, double-blinded, placebo-controlled RCT from 2006, however, found that morphine plus ketorolac provided superior pain relief when compared to morphine alone, and decreased the incidence of vomiting (Safdar, 2006). A 2005 Cochrane review showed that both NSAIDs or opiates reduced pain in acute renal colic, and that NSAIDs had a more favorable side effect profile (Holdgate, 2005).
Most emergency physicians seem to prefer a combination approach of ketorolac (Toradol) (or other NSAID if the patient can tolerate PO) with an opiate agent (typically morphine or hydromorphone). These drugs are often paired with an anti-emetic, as renal colic can cause a significant amount of nausea. One common regimen for an adult is ketorolac 30 mg IV (or 60 mg IM)+ morphine 0.1 mg/kg IV + metoclopramide 10 mg IV. Interestingly, metoclopramide is one of the few anti-emetics that has been studied with regards to renal colic; some small series suggest it also aids in pain relief on its own, and is less sedating than others in its class (Muller, 1990).
It is important to note that parenteral (neither IV nor IM) ketorolac has never really been shown to be superior to oral ibuprofen in terms of pain relief or time of onset to pain relief. If the patient is tolerating PO, ibuprofen is an appropriate substitute.
The prior dogma of forced IV hydration does not improve pain, or increase the rate of stone passage, and may, in fact, worsen pain in cases of obstruction (Springhart, 2006). A few studies have tried intranasal desmopressin, for its antidiuretic properties, and have found it to decrease pain in acute renal colic (Roshani, 2010), although not widely employed in practice.
For home pain control, following a combination method of attack is common as well. Most patients are discharged on a short course of NSAIDs (ibuprofen 400 – 600 mg PO Q8) + an opiate/acetaminophen combination drug (oxycodone/APAP or hydrocodone/APAP) for breakthrough pain.
2. When do you use ED ultrasound? If it shows hydronephrosis, how does this affect your management?
The issue of when and how to employ ultrasound in a patient with presumed (or known) renal colic requires restatement of the goals of ED management. With the growing literature demonstrating the risks of ionizing radiation, CT scanning should be avoided where possible. An ultrasound coupled with a good history and physical examination along with a urinalysis (looking for infection) may obviate the need for a CT scan to attain diagnostic certainty in the right patient population, namely the young and otherwise healthy in whom your suspicion of renal colic is very high (especially those with a history of same). For more on the question of whether or not to employ CT, and the necessity of definitive diagnosis, please also see question four.
Ultrasound in renal colic can involve attempting to visualize the stone, and/or evaluate for unilateral hydronephrosis. With regards to the former, ultrasound has only modest sensitivity, 60-80%, depending on operator and patient characteristics, and does poorly with small stones (<5mm), obese patients, and mid-ureteral stones. This sensitivity, when compared to the 97-99% sensitivity of CT in detecting stones, makes ultrasound seem questionable as a diagnostic modality for visualizing renal stones. In terms of hydronephrosis, however, ultrasound has a sensitivity around 92%, (Sheafor, 2000), a respectable level seen in numerous series on the topic. It is worth mentioning that some radiologists and ultrasonographers believe the false negative rate for hydronephrosis on renal ultrasound to be has high as 22% (Koelliker, 1997) due to anatomic variants, full bladder, etc.. It is in answering the question of whether or not hydronephrosis is present that most emergency physicians employ a bedside renal ultrasound (Noble, 2004).
The presence of a history, physical and urinalysis consistent with nephrolithiasis in a young (most experts arbitrarily say <50) otherwise healthy patient (no underlying renal disease, normal renal function), coupled with the absence of other complications (infection, acute kidney injury, etc.), even with an ultrasound showing hydronephrosis, is still often sent home with Urology follow up in less than one week. Which is to say that even patients with a complete obstruction do not necessarily require emergent decompression of their nephrolithiasis. Some emergency physicians use the presence or absence of hydronephrosis on a bedside ultrasound to risk stratify the time to follow-up and the need to discuss the case with a urologist prior to discharge. There is also a precedent for combining a bedside ultrasound showing hydronephrosis with clinical gestalt to enhance the predicted likelihood of a diagnosis of nephrolithiasis by emergency physicians (Rosen, 1998).
3. Do you give alpha-blockers to aid stone expulsion (tamsulosin or terazosin)?
In 2007, the best studies on this treatment modality were collected and published in a systematic review (Singh, 2007). The conclusion of this systematic review was that the use of alpha-blockers increased the rate of passage of moderately-sized, distal ureteral stones. However, the sixteen studies reviewed were not high quality (none were randomized, none were double-blinded) and the authors stated that further research should be done to confirm their conclusions.
Since then, two studies have found no benefit to tamsulosin for treatment of renal colic. Ferre, et al., 2009, published a randomized, controlled trial 0f 80 subjects which did not show a difference in spontaneous stone passage at fourteen days, time to passage of stone (average stone size 3.6 mm), pain, return ED visits, or adverse outcomes. This was the first published, randomized trial and the first published trial of ED patients.
In December 2010, a multicenter, placebo-controlled, randomized, double-blind study was published in Archives of Internal Medicine, comparing tamsulosin to placebo (Vincendeau, 2010). This study was also performed on ED patients. This trial concluded that tamsulosin did not decrease the time to stone passage (primary endpoint), use of pain medications, or the rate of surgical procedures (secondary endpoints). One caveat to this study was that the vast majority of stones were < 3 mm and some experts contend that tamsulosin may have its greatest benefit in stones > 5 mm. The controversy continues in the Urology literature with some RDCTs amongst clinic patients showing a benefit (Abdel-Mequid, 2010; Al-Ansari, 2010) and others showing none (Hermanns, 2009; Agrawal, 2009). Many, if not most, of our urology colleagues continue to use alpha-blockers for nephrolithiasis, although this practice does not appear to be well-supported by the recent literature, with the bulk of studies showing no effect, especially in ED patients.
4. Who do you CT? Who do you not CT?
Helical CT has become the diagnostic modality of choice in urolithiasis in the last ten years because of its high sensitivity (97%) and specificity (96%) (Sheafor, 2000). In addition to diagnosis, CT provides a great deal of additional information about kidney stones including size, location, presence or absence of hydronephrosis, density of the stone (Hounsfield units) to help determine best treatment options, other complicating issues associated with nephrolithiasis, and other diagnoses if nephrolithiasis is not present.
Many emergency physicians scan all adult patients on their first presentation of unilateral flank pain, presumed to be renal colic. This practice is potentially supported by a small Canadian series that looked at 132 patients and examined the effects of CT scan on diagnosis and disposition, grouped by pre-test likelihood. In 40 of the cases (33%) CT revealed alternate pathology, including 19 with very high pre-test likelihood of a nephrolithiasis diagnosis according to their physician in whom significant other pathology was found (lymphoma, AAA, metastases, undiagnosed malignancies, etc.) (Ha, 2004). This study, and others like it, are a sobering reminder of significant diagnostic uncertainty in the patient with a first episode of unilateral flank pain.
Some commentators, however, feel it is reasonable in a young person with a classic presentation to get an renal ultrasound (and possibly an ultrasound of the abdominal aorta while in the neighborhood, and/or a KUB, although sensitivity is quite low, around 50-60% even for radiopaque stones) and make a diagnosis based on the clinical picture and ultrasound findings, deferring definitive imaging to an outpatient setting, or if a return ED visit is required due to clinical course.