a b s t r a c t

Background: Patients with renal colic commonly present to the emergency department (ED) and are usually treated with analgesics, antiemetics and hydration. Computed tomographic (CT) scan is commonly utilized in evaluating patients with suspected renal colic.

Objectives: We compared diagnosis and treatment plans before and after CT in patients with suspected renal colic with the aim to evaluate how often changes in diagnosis, treatment and disposition are made.

Methods: In this prospective observational study, we enrolled a convenience sample of clinically Stable ED patients older than 17 with suspected renal colic for whom CT was planned. Exclusion criteria were: chronic kidney disease, urinary tract infection, recent CT and history of previous Kidney stone. Pre-CT and Post-CT surveys were completed by the treating provider.

Results: The discharge diagnosis was renal colic in 62 of 93 enrolled patients (67%). Urinalysis showed blood in 52 of these patients (84%). CT confirmed obstructing kidney or Bladder stone in 50 patients. There were five cases of Alternative diagnoses noted on CT scan. After CT scan, 7 patients had changes in disposition. Sixteen providers felt that CT would not change management. In these cases, CT offered no alternative diagnosis and didn’t change disposition.

Conclusion: CT scan didn’t change management when providers did not expect it would. This indicates that providers who are confident with the diagnosis of renal colic should consider forgoing a CT scan. CT scan did occasionally find important alternative diagnoses and should be utilized when providers are considering other concerning pathology.

(C) 2014

Introduction

Renal colic represents a frequent presentation to the Emergency Department (ED). Up to 12% of the population will experience a urinary stone during their lifetime [1]. The classic presentation of urolithiasis is colicky flank pain that radiates to the groin. Gross or microscopic hematuria is often seen with a kidney stone, however, the absence of hematuria does not rule out the diagnosis (sensitivity 84%) [2]. The gold standard for the diagnosis of urolithiasis is computed tomography (CT) scan of the abdomen/pelvis without intravenous or

? Grants: This project was supported by an internal grant for resident education by the HealthPartners Institute for Education and Research.

?? Presentations: This project was presented as a poster abstract at the SAEM

Annual Meeting 2013 in Atlanta, GA.

* Corresponding author.

E-mail address: [email protected] (M.D. Zwank).

oral contrast. The high sensitivity (95%-100%) and specificity (94%- 96%) of CT scans for renal stones makes it a good choice to diagnose urolithiasis [3]. Overall, use of CT scans in the United States has been increasing immensely since 1993 to more than 85 million in 2011 [4]. This carries a heavy burden in monetary expense as well as radiation exposure.to patients.

The clinical management of most patients with renal colic is straightforward: pain is treated, a concomitant urinary tract infection is ruled out, and close follow-up is arranged. It can be argued the CT scan infrequently changes the acute treatment or disposition of these patients. As such, there is increasing concern about the radiation risk that accompanies the CT scans for these patients with a condition that often does not require immediate intervention. Clinicians need to think critically regarding the benefits versus the risks of ordering CT scan in patients with renal colic since most patients are younger and are at higher risk for developing cancer from the radiation.

0735-6757/$ – see front matter (C) 2014 http://dx.doi.org/10.1016/j.ajem.2013.12.031

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There have been few studies that compare diagnosis and treatment plans before and after obtaining CT in patients with suspected renal colic [5]. Despite this, it remains the standard of care in many institutions. Our goal was to evaluate how often changes in diagnosis, treatment, and disposition were made after obtaining the CT scan and our specific aim was to determine if CT alters the diagnosis, management, disposition, and follow-up of ED patients with suspected renal colic.

Methods

This was a prospective observational study conducted from March 2011 through October 2012 at an academic hospital with an Annual patient volume of 75 000. Internal review board approval was obtained. The subjects of the study were the medical providers, though inclusion and exclusion criteria were based on patient characteristics and presentation. We enrolled a convenience sample of emergency department patients with a chief complaint of flank pain or abdominal pain. A research assistant used the electronic track board in the ED to identify appropriate patients. The inclusion criteria were: abdominal or flank pain, most likely diagnosis is renal colic, age greater than 18, and clinically stable. Exclusion criteria included history of previous kidney stone, history of chronic kidney disease (Cr N 2.0), urinary tract infection, recent CT (b 6 months), and history of nephrectomy or renal transplant. Once a patient’s eligibility was determined, the provider was sequentially given a two part survey, with one part to be filled out prior to any testing results including the CT scan, and the second part to be completed after the CT scan (Appendix A and B).

Pre-CT surveys included: 3 most likely diagnoses for the patient, treatment plan, if the provider felt that the CT was going to change the management or disposition and if they anticipated any consults of other specialties. The post CT survey included: final diagnosis, Changes in management related to the CT scan, consults ordered and the patient’s final disposition.

Descriptive statistics were used for analysis.

Results

Ninety-three patients were enrolled (62 male, 31 female). Mean age was 39 (range, 19-74). The providers for these patients included 27 attending physicians, 33 resident physicians, and 30 physician assistants . All providers were from the emergency department except for three rotating residents from internal medicine/pediatrics combined residency. The resident physicians included 5 interns, 12 second residents, 15 third year residents and one first year pediatric emergency medicine fellow.

Sixty-two patients received a final diagnosis of renal colic. The most common alternative diagnosis was Musculoskeletal pain (11 patients) and non-specific back or abdominal pain (13 patients). Fifty had a symptomatic stone defined as a stone within the ureter or bladder detected on CT scan. Some degree of hydronephrosis was noted in all but one of these patients. The patient without hydronephrosis had a 13 mm stone in the renal pelvis that was thought to be symptomatic. Eight additional patients had stones noted within the renal parenchyma but no stone noted more distally.

Of the 4 remaining patients diagnosed with renal colic, one had mild hydronephrosis on CT without any stones and 3 had no findings noted on CT. Median stone size was 2 mm (range 1-13 mm) with 45/50	White blood cells present White blood cell count (median)	56 (60%) 1	15 (48%) 0	41 (66%) 2
stones 5 mm or less (Table 1). Urinalysis of the patients is summarized	Red blood cells	66 (71%)	14 (45%)	52 (84%)

Table 1

Symptomatic stone sizes

Stone size (mm)	Number of patients (%)
1	7 (14)
2	14 (28)
3	11 (22)
4	10 (20)
5	3 (6)
6	3 (6)
7	1 (2)
N 8	1 (2)
Total	50 (100)

Three of these patients were admitted for their diagnoses. The patients with simple ovarian cyst and ovarian tumor were scheduled for close outpatient follow-up.

Consistent with the inclusion criteria, providers felt that renal colic was the most likely diagnosis for all patients before the CT scan though in 57 cases, providers were considering other diagnoses. Prior to imaging, providers felt that all patients would likely be discharged home.

The provider felt that the CT scan would definitely change management for 30 patients, possibly change management for 47 patients and likely not change management for 16 patients. Among the 16 patients with a CT scan ordered despite a perceived lack of benefit, providers Most frequently cited two reasons: Patients had been seen previously in the ED (often several times) and PAs/ residents ordered the CT scan at the request of the attending. The group of definite or likely changes included all patients with significant alternative diagnoses, all seven patients with a change in disposition and all 13 instances of Urology consultation. All 16 providers who thought that CT would not change their management were correct. 10 of these patients had symptomatic Kidney stones ranging in size from 1 to 4 mm and 2 other patients had stones in the renal parenchyma but no obstructing stones. 4 patients had no pathology noted on CT. The final diagnosis of renal colic was more likely if the provider was not considering other diagnoses when ordering the CT (OR, 3.01; 95% CI, 1.13-8.0).

Of the 50 patients with a stone in the ureter or bladder, 13 had a change in their management plan. Most of the time, the change was simply a urology service consultation, There were 7 patients that had stones greater than or equal to 5 mm. Urology was consulted in four of these patients, and three were admitted.

Discussion

Physicians often order CT scans in patients for whom they are quite convinced of the diagnosis for one of several reasons. The usual arguments include determining stone size, location, and any resulting

Table 2

Urinalysis results

All patients Final diagnosis not Final diagnosis renal (n = 93) renal colic (n = 31) colic (n = 62)

in Table 2. Hematuria was present in 52/62 (84%) of the patients with final diagnosis of renal colic and in 14 patients with other final diagnoses.

present Red blood cell	8	0	31
count (median) Leukocyte esterase	22 (24%)	6 (19%)	16 (25.8%)
positive
Nitrite positive	1 (1%)	1 (3%)	0
Bacteria present	25 (27%)	10 (32%)	15 (24%)

Of all 93 cases, there were 5 cases of alternative diagnoses noted on CT scan; these were an ovarian tumor, 2 ovarian cysts (one complex, one simple), uncomplicated diverticulitis, and mesenteric edema.

M.D. Zwank et al. / American Journal of Emergency Medicine 32 (2014) 367–370 369

obstruction as well as ruling out other more ominous pathology. Of the reasons related to the kidney stone, the stone size has the greatest prognostic significance. In our study 42 (84%) of 50 of stones were less than 5 mm. Based on previous epidemiology studies, nearly all of these will pass spontaneously without intervention [6].

Of the 5 alternative diagnoses determined by CT, only 3 likely bear any clinical significance. These included an ovarian tumor, mesenteric edema of unclear etiology and diverticulitis. The other 2 diagnoses were 2 ovarian cysts that were discharged for outpatient follow up. In all of these cases, the provider was anticipating some benefit from the CT scan.

CT also contributed to changes in management of 13 patients and to altered disposition of three patients. All of the changes in management were for urology consultations and the three patients with disposition changes had symptomatic stones equal to or greater than 5 mm. These patients were all admitted to the urology service for procedural management of the stones. Though it is difficult to prove that the CT directly changed the management and disposition of these patients, it seems very likely that the presence of the stones and the size of the stones led to the consultations and admissions.

Providers who felt that there would be no benefit of the CT scan were correct. Of these patients, 75% had evidence of kidney stones either in the kidney or ureter on CT scan. All of these patients were discharged and none had alternative pathology found by CT scan. This would suggest that the provider’s gestalt for renal colic was reasonably accurate.

We are aware of 3 similar studies that evaluated alternative pathology among patients with flank pain. A study done in 2000 by Katz and colleagues came to somewhat similar conclusions as those presented here [7]. This study examined the CT results of 1000 patients with flank pain and found alternative or additional diagnoses in 101 patients. However, there was no comment on whether the findings required immediate or deferred treatment. A retrospective study published in 2006 by Hoppe found similar results [8]. In this study 1500 patients had an unenhanced CT scan due to flank pain, and the results of the CT scans were tabulated. This study found that of the patients enrolled 69% had urolithiasis. However, 14% of the patients had non-stone-related findings that required immediate or deferred treatment. Finally in a recently published article by Moore, 5,383 charts were reviewed. A non-kidney stone diagnosis was found in 5.4% with 2.8% categorized as acutely important [9]. In other words, the CT scan did change management in this minority of patients, and in a way that the providers were perhaps not anticipating. All 3 of these studies differed significantly from our current project in that they were retrospective and examined only diagnoses and not any factors related to provider diagnostic impression.

While the usefulness of CT is undeniable, there is a trade off. It is becoming widely accepted that cancer risks exist due to the high level of ionizing radiation that CTs utilize. Although prospective epidemi- ological studies linking radiation exposure from diagnostic imaging to cancer have not yet been conducted, quantitative information available from studies of Japanese atomic bomb survivors show increased risk of cancer [10]. Using methods published by the National Academy of Sciences’ National Research Council in the Biological Effects of Ionizing Radiation VII Phase 2 report, scientists have postulated that the increased lifetime attributable risks of cancer is likely to be associated with several commonly used CT studies, ranging from 0.23 cancers per 1000 patients for routine head CT scans, to 4 cancers per 1000 patients for multiphase abdomen and pelvis CT scans [11]. Of course, the rate of cancers from CT depends on patients’ ages, as well as the number of CT scans over the course of their lifetime [7]. This is particularly relevant for patients with kidney stones, as they are susceptible to repeat ED visits for renal colic and potentially multiple CT scans [12].

There are other drawbacks as well. CT scans are expensive. While exact charges and costs are difficult to ascertain, it is clear that the

thousands of CT scans performed across the country represent a large expense and a potential source of savings. Meanwhile, in busy EDs, there is High demand for timely CT scans. Any time a patient is in the scanner, access for other potentially critically ill patients is limited.

Physicians are paying attention to these issues and there is a growing body of opinion that CT scan might not be an appropriate initial imaging modality. This movement is especially strong outside of the United States. The European Association of Urology published guidelines in 2011 supporting ultrasound in place of CT as initial imaging [13]. An abundance of literature exists showing decent test performance characteristics of ultrasound including Emergency bedside ultrasound [14,15,5]. All but one of the patients in our study diagnosed with renal colic showed some degree of hydronephrosis on CT. Given this finding, one could argue that ultrasound would have been a good imaging modality at helping to confirm a diagnosis of renal colic while potentially avoiding CT. However, in the United States, both the American Urological Association and the American College of Radiology recommend CT scan as initial imaging for patients with suspected renal colic [16,17] Both societies do note an option for reduced-dose CT with similar test performance characteristics.

There were several limitations to this study. There were a small number of patients/providers enrolled at a single hospital. The limited numbers were mostly due to a need to complete the project while research assistants were available for subject recruitment and the relatively few CT studies that were ordered and met our inclusion criteria. It is difficult to assess if providers had biases when they filled out the surveys. It is possible that surveys were filled out to help justify CT ordering practices. Providers included PAs, residents and attendings–all at various stages in their training and careers. All but 5 of the residents were beyond the first year of training and all of the PAs had experience working in the ED. Of the five CTs ordered by interns, 3 showed kidney stones. At our hospital, all CT scan orders are at least discussed with attending physicians prior to ordering. As such, attendings had input into any CT scan decisions prior to the order. However, attendings did not always evaluate the patient prior to the CT scan being performed. As a general policy, attendings are involved earlier when there is ambiguity about such advanced imaging orders. While the current study evaluates clinicians’ confidence and gestalt, it does not attempt to specify factors that are incorporated into that assessment. Future studies should be directed towards risk assessment of patients presenting with symptoms consistent with renal colic. In the acute setting, the true value of CT is ruling out other acute pathology. If a Decision tool could be developed to help assess the likelihood of renal colic as a cause of a patient’s symptoms, some CT scans could likely be avoided. This tool could include factors such as unilateral symptoms, abruptness of onset, hematuria, sonographic

findings, and others.

In conclusion, CT scan did not change management when providers did not expect it would. This result indicates that providers who are confident with the diagnosis of renal colic and who do not anticipate benefit from a CT scan can trust their Low pre-test probability or ‘gestalt’ of low likelihood of benefit and should strongly consider not ordering a CT scan. These providers could alternatively consider ultrasound to confirm their suspicion. However, CT scan did occasionally find important alternative diagnoses. This is consistent with previous studies and solidifies the use of CT scan when providers are unsure of the diagnosis.

Appendix A. Pre-CT Survey

Do you believe that Renal Colic (i.e., pain due to a stone anywhere in the GU tract) is the source of this patient’s pain? Yes/No

Are you entertaining other diagnoses?

Yes/No

370 M.D. Zwank et al. / American Journal of Emergency Medicine 32 (2014) 367–370

If so, please list your top three diagnoses on your differential.

How do you plan to treat this patient? Circle all that apply.

IV fluids

pain medications – opiates

Pain medications – NSAIDs

Other medications – please specify:

Additional labs – please specify:

Additional imaging – please specify:

Urology consult

Surgery consult

What do you believe will be the patient’s disposition? Circle one.

Discharge home

Admit for observation/further management

Other – please specify:

Based on history and physical exam, do you expect that a CT scan will change your management of this patient? Yes/No/Maybe

Regions Hospital Emergency Department Renal Colic Study Subject #

Appendix B. Post-CT Survey

Do you believe that Renal Colic (ie, pain due to a stone anywhere in the GU tract) is the source of this patient’s pain? Yes/No

Now that you have the CT results, what is your final diagnosis?

Now that you have the CT results, how did you/how do you plan to treat this patient? Circle all that apply.

IV fluids

Pain medications – opiates

Pain medications – NSAIDs

Other medications – please specify:

Additional labs – please specify:

Additional imaging – please specify:

Urology consult

Surgery consult

Now that you have the CT results, what is the patient’s dispo? Circle one.

Discharge home

Admit for observation/further management

Other – please specify:

Regions Hospital Emergency Department Renal Colic Study Subject #

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