Article, Urology

The evaluation and management of urolithiasis in the ED: A review of the literature

a b s t r a c t

Background: Urolithiasis is a common condition in the U.S. Patients frequently present to the emergency depart- ment (ED) for care, including analgesia and treatments to facilitate stone passage.

Objective: With the new evidence concerning the evaluation and treatment of urolithiasis, this review summa- rizes current literature regarding the ED management of urolithiasis.

Discussion: Urolithiasis occurs primarily through supersaturation of urine and commonly presents with flank pain, hematuria, and nausea/vomiting. History, examination, and assessment with several laboratory tests are cornerstones of evaluation. Urinalysis is not diagnostic, but it may be used in association with other assessments. Risk assessment tools and advanced imaging can assist with diagnosis. Computed tomography (CT) is often con- sidered the gold standard. Newer low-dose CT imaging may reduce radiation. Recent studies support ultrasound as an alternate Diagnostic modality, especially in pediatric and pregnant patients. Nonsteroidal anti-inflammato- ry drugs remain first-line therapy, with opioids or intravenous lidocaine reserved for refractory pain. Tamsulosin can increase passage in larger stones but has not demonstrated benefit in smaller stones. Nifedipine and intrave- nous fluids are not recommended to facilitate passage. Surgical intervention is based upon stone size, duration, and modifying factors. Patients who are discharged should be advised on dietary changes.

Conclusion: Urolithiasis is a common disease increasing in prevalence with the potential for significant morbidity. Focused evaluation with history, examination, and testing is important in diagnosis and management. Under- standing the clinical features, risk assessment tools, Imaging options, and treatment options can assist emergency physicians in the management of urolithiasis.

  1. Introduction
    1. Background

Urolithiasis is a common condition evaluated and managed in the emergency department (ED). Nephrolithiasis refers to stones within the kidney, while ureterolithiasis refers to stones within the ureter. Uro- lithiasis refers to stones within the kidneys, ureters, bladder, or urethra. This review will focus on urolithiasis. Approximately 11-16% of men and 7-8% of women will experience symptoms from urolithiasis by age 70 [1-5]. Over 70% of the population affected with urolithiasis is

* Corresponding author at: 3841 Roger Brooke Dr. Fort Sam Houston, TX 78234, United States.

E-mail address: [email protected] (B. Long).

between 20 and 50 years [3-7], with a recurrence rate approaching 50% over 10 years [6-8]. The prevalence of urolithiasis in 1994 was 5.2%, which has more than doubled in 2017. This increase in prevalence is associated with over one million ED visits annually, with over 40,000 surgical interventions [8-12]. Annual costs approach $5 billion, which will likely continue to increase [9,10,12,13]. One major issue with uro- lithiasis is the morbidity due to renal colic, which may result in sudden, Intense pain. Severe sequelae can include sepsis and death from an obstructed, infected stone. Recent prospective data suggest increase in infected urolithiasis incidence and rates of sepsis and severe sepsis, though mortality rates have remained stable [14]. Recurrence is also common, occurring in 15% of patients during the first year and 30- 50% within 10 years [2,12-17].

Men experience stones in a 2:1 ratio when compared with females, predominantly due to diet, climate, and other risk factors [1,2,12,16]. Additional risk factors for stone disease include obesity, decreased fluid intake, increasing age, Caucasian race, Lower socioeconomic status,

https://doi.org/10.1016/j.ajem.2018.01.003 0735-6757/

diabetes, and gout [1,2,5,12,16]. Conditions such as inflammatory bowel disease, pancreatitis, short gut syndrome, and hyperparathyroidism also increase the risk of stone formation due to the associated metabolic ab- normalities [1,2,12,18]

  1. Methods and objectives

In light of new evidence for both the evaluation and treatment of urolithiasis, this review was designed to summarize the current litera- ture regarding the treatment of urolithiasis for the emergency physi- cian. Authors searched PubMed and Google Scholar for articles using a combination of the following keywords and Medical Subject Headings: “Kidney stone“, “renal stone”, “nephrolithiasis”, and “urolithiasis”. The literature search was restricted to studies published in English. Authors decided which studies to include for the review by consensus. A total of 125 articles were selected for inclusion in this review.

  1. Discussion
    1. Anatomy and pathophysiology

Stone formation is predominantly due to an imbalance of urinary solute and solvent [19-21]. Solutes normally dissolve in a solution until a specific saturation point. Once the saturation point is exceeded, stones can form in the urine. Citrate, glycoproteins, and magnesium in- hibit crystal formation, while other materials, referred to as ‘nucleating centers’ (eg, epithelial cells, urinary casts, and red blood cells), form areas for crystal collection [12,18-22]. These nucleating centers acceler- ate crystal growth and coalesce into larger centers. Urinary pH may also affect stone formation by altering solubility. alkaline urine (defined as urinary pH N 6.7) enhances calcium phosphate crystal formation, while acidic urine (defined as urinary pH b 5.5) increases the risk of Uric acid stone formation [22-25]. Calcium stones are the most common, comprising over 80% of all Urinary stones, though many of these include a mixture of solutes [1,2,5,12,20,26-28]. Hypercalciuria, hyperuricos- uria, hypocitraturia, hyperoxaluria, and urinary pH abnormalities are risk factors for stone formation (Table 1) [1,2,5,12,26-30]. Dehydration reduces the available solvent, resulting in more concentrated urine and an increased risk of stone formation. Diets with high salt, high protein, or low calcium content also increase the risk of urolithiasis [5,12,29].

Stones which form in the kidney can be located in the parenchyma, calyx, pelvis, or ureter [1,2,5,12,29,30]. Once the stone has formed, stone size and location have the greatest effect on Patient symptoms and management [12,29,30]. Intra-renal stones are unlikely to result in pain or hydronephrosis [12,29,30].

Likelihood of stone passage relates to location, size, shape, and de- gree of ureteral obstruction [5,12,26,27,31]. As stones move down the ureter, there are three areas of decreased luminal diameter: 1) the ureteropelvic junction, 2) the site where the ureter crosses the iliac ves- sels, and 3) the area where the ureter meets the bladder wall and emerges in the ureteral orifice. These sites may result in stone impaction and obstruction [5,12,26,27,31].

Urinary flow obstruction can cause increased intraluminal pressure and hydronephrosis, which leads to stimulation of urothelium nerve endings and increased ureteral wall tension [12,32,33]. This causes col-

History and physical examination

Patients may present with a variety of symptoms. The most common symptoms are flank pain, hematuria, nausea, and vomiting [12,28, 31-35]. A variety of conditions can mimic renal colic, but the history, physical examination, and targeted testing are often diagnostic [12, 31-34]. Pain nature and location often changes based upon stone location, though the specific stone location is not necessarily directly correlated with the location of the pain [32,36]. The pain typically begins as waxing and waning in the acute phase. Pain that is constant in the acute phase can indicate a more severe obstruction, while intermittent pain is more commonly associated with an incomplete obstruction [2,3,12]. Due to the dual innervation of the gastrointestinal, genitouri- nary, and somatic systems, patients may feel pain in the intestines, groin, bladder, or genitalia [12,32,37,38]. Ipsilateral genital pain is a common location for referred pain with Distal ureteral stones. Stones not causing obstruction are believed to be asymptomatic, and findings of a nonobstructive stone on imaging warrant consideration of another etiology for the patient’s symptoms. Nausea and vomiting occur in ap- proximately half of patients with urolithiasis [34].

Hematuria is most commonly microscopic (up to 90% of cases), though it may be macroscopic. Using hematuria to predict the presence of urolithiasis possesses an accuracy of only 60%, and the absence of he- maturia does not rule out urolithiasis [5,12,28,32,35-37]. Hematuria is most common on the first day of symptoms, with sensitivity of 95%, but this decreases to 65% by days 3 to 4 [28]. Though approximately 85-90% of patients experience some form of hematuria, approximately 25% of patients with hematuria and flank pain do not have radiologic imaging evidence of urolithiasis [35].

Symptoms associated with urinary tract infection are common, in- cluding urgency, dysuria, frequency, and pain at the urethral meatus. These symptoms arise from bladder urothelial irritation as the stone passes the bladder wall. Once a stone passes completely into the blad- der, it may become asymptomatic. Urethral stones are commonly asymptomatic [28,33,34,39,40]. Older patients will more often present atypically, though CVA tenderness and hematuria remain common [39]. Careful inquiry concerning these symptoms is warranted for older patients.

Fevers, chills, and rigors are usually not present in uncomplicated urolithiasis and should raise concern for an infected stone [12,28, 38-40]. Hemodynamic abnormalities typically resolve with analgesia in patients with urolithiasis [41]. An upper urinary tract infection with

Table 1

Stone type and risk factors.

Stone type Metabolic abnormality Clinical setting Calcium oxalate Hypercalciuria Hyperparathyroidism,

immobilization, high vitamin D, sarcoidosis, Cushing syndrome, increased dietary sodium, genetic predisposition

Hyperoxaluria Increased oxalate absorption (inflammatory bowel disease), primary hyperoxaluria, high doses

of dietary Vitamin C

icky pain and prostaglandin release, associated with ureteral wall smooth Muscle spasms and pain. Renal and ureteral afferent nerves enter the spinal cord at T11 to L2, which are shared with gastrointestinal (GI) organs, other urinary organs, and genitalia. Patients may present with pain in association with these systems, which may mimic other medical and surgical conditions [12,28,32-34]. Nausea and vomiting re-

sult from stimulation of the celiac axis and vagal nerve afferents. Hema- turia is caused by the stone injuring the ureteral and bladder wall, as

Calcium phosphate Hypocitraturia

Hypercalciuria High Urine pH (N 7)

Struvite High urinary ammonium and bicarbonate levels

Uric acid Low urine pH (b5.5) Hyperuricosuria

Similar to calcium oxalate, as well as distal renal tubular acidosis, and intake of medications with Carbonic anhydrase inhibitory action

Urinary tract infection with urease-splitting organisms

Metabolic syndrome, insulin resistance, type 2 diabetes

well as irritation of superficial blood vessels [12,28,32-35].

Cystine Cystinuria Genetic disorder

urolithiasis is a major risk factor for sepsis and considered a Urologic emergency [38-40].

The patient should also be asked concerning prior episodes, proce- dures required for stone removal, family history of urolithiasis, fevers, chills, rigors, ability to tolerate oral intake, vomiting, and other urinary symptoms.

A patient with renal colic classically is unable to find a comfortable position, though this is not universal. Due to pain, tachycardia and hy- pertension may also be present. However, fever and hypotension are rare and warrant close evaluation for associated UTI or abscess and sep- sis. Upon examination, costovertebral tenderness is present in 25-52% of cases and is often severe [5,12,28,42]. The Abdominal examination usually reveals a soft, nontender, and nondistended abdomen. However, guarding (61%), rebound tenderness (29%), and rigidity (8%) can be present [12,28,42]. Evaluation of the genitalia and groin should be normal.

Laboratory testing

Laboratory testing in the ED often involves several assessments in- cluding serum chemistry and urinalysis. Patients may present with a small decrease in creatinine clearance, resulting in slight elevation of serum Creatinine levels [12,43]. However, this is rarely significant enough to qualify as acute renal injury [12,43]. More severe creatinine elevation may be found in patients with a solitary kidney or baseline elevation, though the most common cause is pre-renal injury due to de- hydration from nausea and vomiting [7,36,43]. Females of reproductive age require testing for pregnancy [5,7,12]. The serum white blood cell count component of the complete blood count may depict eleva- tion with increase in neutrophils, which can be due to a stress response with pain or urinary tract infection [12,40]. Physicians should not rely solely on CBC to differentiate complicated urolithiasis with infection from an uncomplicated stone, but rather as a supplement to clinical de- cision-making.

The urinalysis often demonstrates microscopic hematuria. Urinary crystals are common in normal patients and should not be used for di- agnosis of urolithiasis [28,31]. The presence of urinary white blood cells (WBCs), Leukocyte esterase, and nitrites can suggest urinary tract infection . Urinary WBCs are not definitive for UTI, as urolithiasis can cause ureteral inflammation; however, urinary WBCs can be used to assist in Treatment decisions. Approximately 8% of all patients with suspected urolithiasis experience concomitant UTI, diagnosed by uri- nary culture [44]. In one study by Abrahamian et al., pyuria N 5 WBC per high powered field (hpf) possessed a sensitivity of 86% and specific- ity 79% for UTI, while N 20 WBC/hpf demonstrated a sensitivity of 68% and specificity of 93%. Other moderate predictors of UTI with urolithiasis included Female gender, dysuria, increased Urinary frequency, chills, subjective fever, and measured fever N 37.9 ?C [44]. Patients with great- er levels of pyuria demonstrate greater risk of UTI in urolithiasis, with 10-20 WBC/hpf associated with a 9.1% likelihood of positive urine cul- ture, while N 50 WBC/hpf is associated with a 60% positive urine culture rate [45]. The presence of urinary nitrites or leukocyte esterase is asso- ciated with an increased likelihood of UTI [41,44,45]. The degree of leu- kocyte esterase positivity in urinalysis is also correlated with a higher rate of positive urinary cultures [45]. However, urinalysis with WBCs is not definitive for UTI. Therefore, it is important to also consider the clinical situation and other patient factors.

Other testing to assist in determining the etiology of urolithiasis in- cludes stone analysis, urine metabolic evaluation, and serum metabolic testing [1,2,5,12,46,47]. Many of these tests focus on electrolyte abnor- malities in the urine and serum. serum calcium, phosphorus, magne- sium, oxalate, sulfate, citrate, ammonium, cysteine, vitamin D levels, lactate dehydrogenase, and parathyroid hormone can assist with outpa- tient management, while urinalysis including urine electrolytes, uric acid, pH, calcium, and creatinine is also helpful [1,2,5,12,46,47]. This is

not required during the patient’s initial ED presentation, but may assist with outpatient management.

Risk assessment tools

In 1993, Elton et al. described a four-item, clinical prediction rule to diagnose ureteral calculi in the ED setting [48]. The authors used a com- bination of hematuria, flank pain, acute onset of symptoms, and a posi- tive kidney, ureter, bladder (KUB) x-ray to correctly classify 83% of patients in the derivation group and 90% of patients in the subsequent validation [48]. However, no further validations were performed on this rule.

In 2014, Moore et al. derived and validated the STONE score (Fig. 1) [49]. This scoring tool uses a combination of five criteria (sex, timing, or- igin, nausea, and hematuria) to stratify patients into a low, moderate, or high probability of having a Ureteral stone. Patients in the low probabil- ity group (score 0-5) had an 8.3% and 9.2% likelihood; patients in the moderate probability group (score 6-9) had a 51.6% and 51.3% likeli- hood; and patients in the high probability group had an 89.6% and 88.6% likelihood in the derivation and validation groups, respectively [49]. Subsequent external validations demonstrated a 13.5-21.8% prev- alence in the low probability group, 32.3-80.1% in the moderate proba- bility group, and 72.7-98.7% in the high probability group [50-53]. Schoenfeld et al. performed a validation study of the STONE score in a retrospective cohort study in patients ages 18 to 50 years presenting with flank pain consistent with uncomplicated urolithiasis [50]. Authors found a specificity of 84.4%, sensitivity of 78.6%, positive predictive value of 84.6%, and an area under the curve of 0.87 for the receiver operating characteristic curve when a score of >=8 was utilized [50]. Kim et al. mod- ified the score by adding a family history of stones and C-reactive pro- tein with a small improvement in test characteristics [53]. Daniels et al. added point-of-care ultrasound to the STONE score to create the STONE PLUS tool [54]. In the latter study, the presence of moderate or severe hydronephrosis improved the test characteristics in the low and moderate probability groups, but did not affect the high probability group [54]. Importantly, both modified STONE scores require further validation prior to routine use. While the STONE score is not able to defer CT imaging in all patients, it may be a valuable tool for engaging in shared decision-making with patients regarding imaging choices [52].

A separate score entitled the Risk of Kidney Stone (ROKS) nomo- gram was developed by Rule et al. in 2014 and uses a multivariate model to determine the likelihood of stone recurrence [55]. This rule in- cludes age, gender, race, family history of renal stones, location of prior stones, prior episodes of asymptomatic stones, gross hematuria, and Uric acid levels. Patients with high scores are at increased risk of stone recurrence and may benefit from dietary and lifestyle changes [55].

Imaging

Urolithiasis may be assessed with x-rays, ultrasound, computed to- mography (CT), or magnetic resonance imaging (MRI). While the ma- jority of calcium-containing stones are visible on x-ray, certain stone compositions (eg, cystine and uric acid stones) are radiolucent and not identifiable on x-rays [26,56]. Additionally, overlying bowel gas, pa- tient body habitus, and extra-renal calcifications can further limit the di- agnostic ability of x-rays [56]. As a result, the sensitivity and specificity have been reported as low as 59% and 71%, respectively [57]. Moreover, x-ray does not allow for the assessment of hydronephrosis or specific stone location [56,57].

Consequently, non-contrast CT has become the gold standard imag- ing modality for most patients with acute urolithiasis [56,58]. CT is able to detect and measure ureteral stones with a sensitivity and specificity of 98 to 100% regardless of size or stone composition [58,59]. Addition- ally, CT can help to determine the type of stone and the anticipated dif- ficulty with lithotripsy [60]. CT is likely able to diagnose other

Fig. 1. STONE scoring tool.

conditions responsible for patient symptoms if not due to urolithiasis. However, CT imaging exposes patients to radiation and several studies have already highlighted the significant radiation exposure that occurs between the initial presentation and follow-up imaging among patients presenting with urolithiasis [61-64].

This has led many to advocate for the use of low-dose CT imaging for renal stones [65,66]. Using the low-dose parameters has been demon- strated to reduce radiation exposure, while maintaining similar diag- nostic accuracy in most patients [67-70]. However, this modality was less accurate for detecting small stones (ie, b 3 mm) and when per- formed on patients with a body-mass index (BMI) N 30 kg/m2 [67-70]. This may be partially counteracted by increasing the radiation dose in proportion to BMI, while still maintaining lower overall radiation expo- sure than standard-dose CT [70,71]. Advances in technology have led to the recent development of ultra-low-dose CT, with radiation exposure levels approaching that of x-rays [72]. While further studies are needed, this shows significant promise in early literature [72,73].

It is often recommended to avoid intravenous contrast when

performing a CT to evaluate for urolithiasis due to concern regarding stone detection. However, intravenous contrast may be needed for the concomitant evaluation of alternate etiologies for the patient’s symp- toms. While the literature is limited, two studies have demonstrated that CT with intravenous contrast is able to reliably detect stones

>= 3 mm with 97-100% accuracy [74,75].

Ultrasound has been proposed as an alternate imaging modality to evaluate for the presence of urolithiasis. Ultrasound offers the advan- tage of not exposing the patient to ionizing radiation, as well as the abil- ity to be performed rapidly at the bedside. The presence of a stone is often indirectly assessed by evaluating for hydronephrosis. However, it is important to note that 11-15% of patients with urolithiasis may not have hydronephrosis on examination [76,77]. In some cases, this may be due to dehydration and can be reassessed after the patient has received intravenous fluids [78]. Interestingly, several studies have found that the degree of hydronephrosis has been correlated with in- creased stone size [76,77], while another study found that absence of hydronephrosis was associated with a significantly decreased rate of urologic interventions [79].

Stones can also be directly visualized on ultrasound, appearing as hyperechoic lines with distal shadowing. Adding Color Doppler will

often demonstrate the “twinkling sign”, which is the appearance of al- ternating colors located deep to the stone (ie, where the shadowing is typically seen on gray scale imaging) [80-83]. The “twinkling sign” has been suggested to be highly specific for the presence of a stone [80-83]. Another technique is to visualize the bladder in transverse view and assess for the presence of ureteral jets [84]. These will appear as intermittent bursts of fluid seen on each side of the bladder using color Doppler. Unilateral absence of ureteral jets is specific for the pres- ence of an obstructing ureteral stone [84-86].

Studies have demonstrated that ultrasound is 54-57% sensitive and 91-98% specific for the diagnosis of urolithiasis [87,88], leading some societies to recommend ultrasound as the initial imaging modality [26], while others recommend CT [65,89]. A recent non-inferiority study by Smith-Bindman et al. randomized ED patients to point-of- care ultrasound, radiology ultrasound, or CT [90]. Overall, 2759 patients were included with equal distributions to each group [90]. Ultrasound was determined to be 85% sensitive and 50% specific when compared with a gold standard of witnessed stone passage or surgical intervention [90]. However, there were no significant differences in outcomes be- tween all three groups and a very low rate of serious adverse events, while also reducing cumulative radiation exposure in both ultrasound groups [90]. Many of the patients randomized to ultrasound ultimately received CT [90]. Of note, while ultrasound was a less expensive individ- ual test, the overall Healthcare costs were not significantly different be- tween both groups [91]. Ultrasound is the imaging modality of choice for pregnant and pediatric patients, but may also be particularly valu- able to support the diagnosis when there is a moderate or High clinical suspicion of urolithiasis [26,56,84,86,92,93].

While not commonly utilized for the evaluation of acute urolithiasis, MRI is useful for the identification of urolithiasis in pregnant patients when ultrasound is non-diagnostic [86,92]. MRI has been suggested to be 93% accurate, and similar to ultrasound, does not require any ionizing radiation [94]. However, MRI is significantly more time-consuming and costly than the other modalities described above [86].

Treatment

Treatment of urolithiasis may involve medical or surgical interven- tions (Table 2). Pain relief should be initiated immediately in patients presenting with suspected urolithiasis. The pain associated with renal colic is due to the obstruction of urinary flow and resultant wall tension in the urinary tract [95,96]. This stimulates the release of prostaglandins, which further increase the pressure and pain [95,96]. Due to their direct effects on prostaglandin release and the inflammatory cascade, nonste- roidal anti-inflammatory drugs (NSAIDs) are an effective analgesic in patients with acute renal colic [97,98]. Opioids should be considered for refractory pain or patients who have contraindications to NSAIDs [96].

Another option that has been suggested is intravenous lidocaine. Li- docaine has been previously studied for the treatment of chronic pain with promising results [99]. The effect has been hypothesized to be due to inhibition of central and peripheral voltage-dependent sodium channels, G protein-coupled receptors, and N-methyl-D-aspartate (NMDA) receptors, though the primary mechanism remains unclear [100]. This has prompted several authors to study this in the treatment of renal colic [100-102]. One study of 240 ED patients randomized to li- docaine 1.5 mg/kg or morphine 0.1 mg/kg identified a statistically sig- nificant improvement in the pain scores at 5, 10, 15, and 20 min for the lidocaine treatment group [102]. Another randomized controlled trial of 110 ED patients compared morphine (0.1 mg/kg) with and with- out lidocaine (1.5 mg/kg) assessing time to being pain-free [100]. While the difference was not statistically significant, there was a trend favor- ing intravenous lidocaine [100]. No serious adverse events were identi- fied in either study [100,102]. Of note, none of the patients in either group received NSAIDs, so it remains unclear how beneficial lidocaine will be in patients after receiving NSAIDs [100,102].

Several meta-analyses have demonstrated the effectiveness of alpha-adrenergic agonists (eg, tamsulosin) for the medical manage- ment of urolithiasis, demonstrating higher stone passage rates [103-105], quicker time to stone passage [103], decreased analgesic requirement [103,104], and lower rates of hospitalization [103,104]. Importantly, the effects were only seen in patients with large stones (5-10 mm) with no difference in outcomes among patients with small- er stones (b 5 mm) [104,105]. Silodosin is a newer, selective alpha-1A- adrenoreceptor agonist which has been suggested to be superior to tamsulosin and placebo for the treatment of larger ureteral stones, but further trials are needed prior to routine use [106,107]. Nifedipine has also been suggested to facilitate stone passage by directly relaxing the ureteral wall. However, several studies have found that nifedipine is in- ferior to tamsulosin with respect to stone passage rates and pain relief, so it is not recommended at this time [108,109]. When prescribing tamsulosin, it is important for patients to be aware of the risk of ortho- static hypotension, which can be particularly problematic in older pa- tients. Patients should be advised on strategies to reduce orthostatic symptoms, and consideration should be given for taking the medica- tions at night before going to sleep.

Intravenous fluids have also been proposed as a treatment option. By

increasing urinary flow, it has been proposed that the stone may be pushed through the ureter [110]. However, this has not been demon- strated to facilitate stone passage or affect pain scores [110]. Therefore, intravenous fluids should be reserved for the treatment of dehydration and should not be considered as part of medical expulsive therapy.

The decision to pursue surgical intervention (eg, lithotripsy, ureteroscopic removal, percutaneous nephrolithotomy) often depends upon stone size, duration of symptoms, and modifying factors (eg, soli- tary kidney, renal transplant, renal dysfunction, associated pyelonephri- tis, refractory pain) [96,111]. One study found that the passage rate for 1-mm stones was 87%, 2-to-4-mm stones was 76%, 5-to-7-mm stones was 60%, 7-to-9-mm stones was 48%, and N 9-mm stones was 25% [112]. Another study found that stones <= 5 mm had a 68% change of spontaneously passing, while stones measuring 5-10 mm had a 47% passage rate [113]. Stone location has also been associated with differences in stone passage rates. Stones located in the proximal ureter (ie, above the sacroiliac joints) had a 48% rate of Spontaneous passage, middle ureter (ie, overlying the sacroiliac joints) had a 60% passage rate, distal ureter (ie, below the sacroiliac joints) had a 75% passage rate, and stones at the ureterovesical junction had a 79% passage rate [112]. While there is no strict size cutoff, most experts consider surgical intervention when the stones are N 15 mm or fail to spontaneously pass with medical management alone [26].

Disposition

Patients who have uncomplicated urolithiasis, are able to take fluids by mouth, not toxic appearing, and have pain adequately controlled are often appropriate for discharge [18,34,41,92,93] (Fig. 2). Most patients

Table 2

Treatment options for urolithiasis.

Treatment option Recommendation

NSAIDs Treatment of choice. May be given orally or parenterally.

Opioids Useful for severe, refractory pain and in those with contraindications to NSAIDs.

Intravenous lidocaine Initial data suggests possible benefit. Further studies needed.

Tamsulosin Beneficial for stone N 5 mm. side effects include orthostatic hypotension.

Nifedipine Not recommended at this time.

Intravenous fluids Use for hydration only. Not recommended to facilitate

stone passage.

NSAIDs, nonsteroidal anti-inflammatory drug.

with a first episode of urolithiasis may follow up with their primary care provider. Urology follow-up is recommended for patients with stones >= 5 mm or Recurrent episodes of urolithiasis [18,33,34,41,92, 93]. Patients with a suspected UTI and stone without fever, toxic appear- ance, or hydronephrosis may be discharged with oral antibiotics if close follow-up can be obtained. However, patients with intractable pain or vomiting, sepsis, single or transplant kidney with obstruction on imag- ing, acute renal failure, severe medical comorbidities, inability to follow- up, and those of advanced age warrant consideration for admission and Urology consultation. Other components associated with need for ad- mission include evidence of kidney injury or infection, history of prior urologic procedure, need for Opioid analgesia, and increasing size of stone [114]. Markers for ED revisit include proximal stone location, age b 30 years, and need for IV opioids [115]. If appropriate for dis- charge, patients should be provided with medications such as NSAIDs, oral opioid analgesics, and an antiemetic, and close follow-up should be ensured [18,92,93] (Fig. 2).

Prevention

It has been estimated that almost 50% of all patients with urolithiasis will have a recurrence within ten years [15,116]. While not all risk fac- tors are controllable, there are several dietary changes recommended to reduce the risk of stone recurrence. Patients should be advised to de- crease their sodium and animal protein intake, while maintaining ade- quate calcium intake [60,117-122]. Patients should also be counselled to increase water consumption with a goal of N 2l of fluid intake daily [60,119-123]. Some experts also recommend initiating a thiazide med- ication or citrate salt for patients with frequent episodes, though this may be deferred to the patient’s primary care physician or urologist [60,119,122,124,125].

  1. Conclusions

Urolithiasis is a common medical condition, resulting in over one million ED visits annually. The most common presentation includes flank pain, hematuria, nausea, and vomiting. However, classic symp- toms may not always be present. Urinalysis should not be relied on for diagnosis or exclusion of urolithiasis. Risk assessment tools and ad- vanced imaging may facilitate the diagnosis of urolithiasis. Imaging options include x-ray, CT, ultrasound, and MRI. While CT is often considered the gold standard for imaging, it is associated with signifi- cant radiation exposure, especially among patients with frequent episodes of urolithiasis. Newer low-dose CT imaging may reduce radia- tion exposure. Recent research has supported ultrasound as an alternate diagnostic modality, especially in pediatric and pregnant patients. NSAIDs remain the first-line therapy with opioids or intravenous lido- caine reserved for refractory pain. Tamsulosin can facilitate stone pas- sage in larger stones, but has not been demonstrated to be beneficial in smaller stones. Nifedipine and intravenous fluids are not recom- mended to facilitate passage. Surgical intervention is based upon stone size, duration, and modifying factors. Patients who are discharged should be advised on dietary changes. Knowledge of the clinical fea- tures, risk assessment tools, imaging options, and treatment options can assist ED providers in the evaluation and management of patients with urolithiasis.

Conflicts of interest

None.

Acknowledgements

MG, BL, and AK conceived the idea for this manuscript and contrib- uted substantially to the writing and editing of the review. Dr. White ap- proved this topic for review. This manuscript did not utilize any grants,

Image of Fig. 2

Fig. 2. Urolithiasis pathway.

and it has not been presented in abstract form. This clinical review has not been published, it is not under consideration for publication else- where, its publication is approved by all authors and tacitly or explicitly by the responsible authorities where the work was carried out, and that, if accepted, it will not be published elsewhere in the same form, in English or in any other language, including electronically without the written consent of the copyright-holder. This review does not reflect the views or opinions of the U.S. government, Department of Defense,

U.S. Army, U.S. Air Force, or SAUSHEC EM Residency Program.

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