Article

ED presentations of acute renal infarction

Brief Report

ED presentations of acute Renal infarction

Chien-Cheng Huang MDa,b, Hong-Chang Lo MDc, Hsien-Hao Huang MDc,

Wei-Fong Kao MDc, David Hung-Tsang Yen MD, PhDc,d,*, Lee-Min Wang MDc,

Chun-I Huang MDc, Chen-Hsen Lee MDc

aDepartment of Emergency Medicine, Cathay General Hospital, Taipei, Taiwan, R.O.C.

bFu Jen Catholic University School of Medicine, Taipei, Taiwan, R.O.C.

cDepartment of Emergency Medicine, Taipei Veterans General Hospital, College of Medicine, National Yang-Ming University, Taipei, Taiwan, R.O.C.

dInstitute of Emergency and Critical Care Medicine, National Yang-Ming University, Taipei, Taiwan, R.O.C.

Received 5 April 2006; revised 20 June 2006; accepted 21 June 2006

Abstract

Objective: The objective of the study was to investigate initial clinical characteristics that can suggest an early diagnosis of patients with acute renal infarction presenting with flank and/or abdominal pain in the emergency department (ED).

Methods: From January 1, 1996, through December 31, 2005, 20 adult patients with renal infarction diagnosed by contrast-enhanced computed tomography in the ED were enrolled. Medical records, including demographic data, risk factors for thromboembolism, initial clinical presentations, laboratory data, treatment programs and outcomes, were retrospectively reviewed and analyzed.

Results: Mean patient age was 60.3 years (range, 21-80). The estimated incidence of renal infarction was 0.004% (20 of 481540) among the ED census. The median time of onset of symptoms before the ED visit was 31 hours (range, 1-285). Eighteen patients (90%) had a history of more than 1 risk factor for Thromboembolic events. In clinical presentations, all the patients had either abdominal or flank pain and tenderness. Nineteen patients (95%) had an elevated serum lactate dehydrogenase level with a mean F SD of 812.1 F 569.4 U/L. Sixteen patients (80%) presented with the triad–persisting flank or abdominal pain/tenderness, elevated serum lactate dehydrogenase level, and proteinuria. Among all 20 patients, 10 patients (50%) were diagnosed as having renal infarction at the initial ED visit. No specific clinical characteristics could be identified to distinguish those patients diagnosed early and those with delayed diagnosis. All 20 patients received medical treatment with coumadin, which was given in combination with heparin treatment in 11, peripheral intravenous and/or local intra-arterial thrombolytics with urokinase in 5, and Mitral valve replacement in 1. No patient died. Although 4 patients had a mildly elevated serum creatinine level (N1.5 mg/dL) during hospitalization, none of them needs dialysis after more than 1 year of follow-up.

Conclusions: In this study, we delineated specifically clinical features for emergency physicians to raise their suspicion index for an early diagnosis of patients with renal infarction, a disease which is uncommon and is usually delayed or missed at initial ED presentation.

D 2007

* Corresponding author. Tel.: +886 2 8757377; fax: +886 2 8757842.

E-mail address: [email protected] (D.H.-T. Yen).

0735-6757/$ – see front matter D 2007 doi:10.1016/j.ajem.2006.06.010

Introduction

Renal infarction is an uncommon disease with an estimated incidence rate of about 0.007% of emergency department (ED) visits [1,6]. Because of its rareness and its often being mimicked by other more common diseases such as urolithiasis, lumbago, or other abdominal lesions at clinical presentation, acute renal infarction is rarely detected early in clinical practice [5,7]. Previous reports demonstrat- ed that acute renal infarction was usually found incidentally while treating patients with other diseases [1,2,6,7] or an uncommon mimic [8] presenting with flank pain. In emergency medicine, sporadic cases, presenting with common clinical characteristics or an Unusual presentation or complication, have been reported in recent years [3,9-13]. Whenever acute renal infarction is not diagnosed at the time of presentation, no definite treatment can be administrated. Patients who have delayed diagnosis or are misdiagnosed initially will be subject to persistent clinical symptoms, risk of Renal impairment [4,7], and even possible mortality [4,7]. It should be emphasized that an early diagnosis of acute renal infarction is mandatory to establish effective immedi- ate and long-term therapy for the preservation of renal function [1]. The purpose of this study was to investigate the clinical characteristics that can be reasonably suggestive of further diagnostic imaging for an early diagnosis of acute renal infarction in patients who present with acute flank and/or abdominal pain in the ED.

Table 1 Summary of demographic data, risk factors for

thromboembolism, etiology, and affected sites in all study patients (N = 20)

Age (y)a Male-female

Risk factors for thromboembolismb,c Hypertension

Atherosclerosis of abdominal aorta on contrast-enhanced CT

Atrial fibrillation

Prior thromboembolic eventsd Valvular heart disease Coagulation dysfunction or hematologic disease

Etiology of renal infarctionb Cardiac origine Coagulation dysfunction or hematologic disease

Spontaneous Renal artery dissection Idiopathic

60.3 F 16.5

4:1

13 (65%)

10 (50%)

10 (50%)

5 (25%)

4 (20%)

2 (10%)

15 (75%)

2 (10%)

1 (5%)

2 (10%)

Methods

Cases were initially identified via a hospital computer database using a hospital discharge diagnosis with Interna- tional Classification of Diseases code of 593.81. Only adult patients (age N14 years) with a diagnosis of renal infarction confirmed by contrast-enhanced computed tomography (CT) [1] in our ED were included in this study. From January 1, 1996, to December 31, 2005, a total of 20 adult patients met the inclusion criteria of renal infarction in the

Results

Twenty adult patients who met the inclusion criteria for renal infarction were recruited for this study. Eighteen additional hospitalized patients, whose renal infarction was trauma-induced or was simultaneously associated with other cardiovascular events or systemic life-threatening diseases such as acute myocardial infarction, Infective endocarditis, mesenteric infarction, and sepsis, were ex- cluded to eliminate possibly confounding data from this study. The incidence of renal infarction was 0.004% (20 of 481540) among the total ED census. The mean age of all 20 patients was 60.3 F 16.5 (SD) years. Only 2 patients were aged younger than 45 years. One 21-year-old female patient had valvular heart disease, and a 38-year-old male patient had protein C and Protein S deficiency (Table 1). Eighteen patients (90%) had a history of more than 1 risk factor for thromboembolic events; 12 patients (60%) had more than 2 risk factors. The most common etiology of

ED. The CT image of renal infarction was defined as a

triangular-shaped peripheral area of the renal parenchyma

Side of renal infarction on contrast-enhanced CTb

that was slightly hypodense on native scans at the

Right

9 (45%)

predefined display window settings, had soft-tissue densities

Left

7 (35%)

(20-40 HU), remained hypodense after contrast injection,

Bilateralf

4 (20%)

and showed no enhancement [1]. Additional features

included cortical rim sign [15], perirenal stranding with

Concomitant splenic infarction on

contrast-enhanced CTb,f

4 (20%)

thickening of the Gerota fascia, and an absence of urinary excretion of Contrast material [6]. The medical records of all

20 patients, including demographic data, risk factors for thromboembolism, initial clinical presentations, laboratory data, treatment programs, and outcomes, were reviewed and analyzed. Clinical features were compared by univariate analysis. Continuous data are presented as mean F SD or median (range) when appropriate. Dichotomous values were

given as frequencies and percentages.

a Mean F SD.

b Number (%).

c The risk factors for thromboembolism were quoted from previous articles [1,2,4-7].

d Including coronary artery disease, cerebral infarction, and peripheral artery disease.

e Including atrial fibrillation, cardiac thrombus, or valvular heart disease.

f Among the 4 patients, 3 patients had bilateral renal infarction and concomitant splenic infarction.

renal infarction was considered to be of cardiac origin, which was observed in 15 patients (75%) who had either atrial fibrillation, valvular heart disease, or cardiac throm- bus. Right side renal infarction was more frequent than left side or bilateral involvement. Four patients (20%) had bilateral renal infarction, including 3 who had concomitant splenic infarction.

Table 3 Summary of treatment and outcomes in all study

patients (N = 20)

Analgesics use

(intravenous NSAID or narcotics)

Poor response before anticoagulation or thrombolytics treatmenta,b

Pain subsided after anticoagulation or thrombolytics treatment (h)c

Treatment programs Anticoagulantsb Coumadin only Coumadin + UFH Coumadin + LMWH

19/20

19 (100%)

66.8 F 28.8

14 (70%)

2

4

7

Coumadin + UFH + UK (IV + IRA)

Anticoagulant + MVRb Coumadin + MVR

Renal function impairment due to renal infarction initiallyb,d

Persistent renal function impairment after treatmentb

Mortality Hospital stay (d)c

2

1 (5%)

1

4 (20%)

3 (15%)

0

12.1 F 6.5

NSAID indicates nonsteroidal anti-inflammatory drug; UFH, unfractio-

nated heparin; MVR, mitral valve replacement; LMWH, Low Molecular Weight Heparin; UK, urokinase; IRA, intrarenal arterial injection; IV, intravenous injection.

a At least 2 analgesics used or persistent pain after analgesics were given.

b Number (%).

c Mean F SD.

d New onset serum creatinine level z1.5 mg/dL.

Among the 20 patients, there were 19 (95%) who had sudden onset of clinical presentations. The median time from onset of symptoms and signs to the ED visit was

31 hours (range, 1-285) (Table 2). The median time of confirmed diagnosis by contrast-enhanced CT after the ED visit was 3 hours (range, 2-72). All patients had either abdominal or flank pain and tenderness. Fourteen patients (70%) had both flank and abdominal manifestations. With respect to laboratory data, 19 patients (95%) had an elevated serum Lactate dehydrogenase level with a mean F SD of 812.1 F 569.4 U/L. Mildly elevated mean white blood cell count and Serum C-reactive protein levels were

Coumadin + UFH + LMWH

1

Anticoagulant + thrombolyticsb

5 (25%)

Coumadin + UK (IRA)

2

Coumadin + UFH + UK (IV)

1

found. Urinalysis using a dipstick revealed proteinuria in 16 patients (80%) and hematuria in 9 patients (45%).

Table 2 Summary of initial clinical presentations and

laboratory data in all study patients (N = 20)

Duration of symptoms/signs before ED visit (h) Median (range) 31 (1-285)

Duration of making diagnosis after ED visit (h)

Median (range)

Sudden-onset symptoms/signsa Symptoms/signsa

Abdominal or flank pain/tenderness

3 (2-72)

19 (95%)

20 (100%)

Laboratory data (reference range)

WBC (4500-11000/mm3)b

Segment neutrophil (45%-75%)b LDH (95-213 U/L)b,c

CRP (0-0.5 mg/dL)b

AST (5-45 U/L)b

ALT (0-40 U/L)b

ALP (10-100 U/L)b

BUN (0-20 mg/dL)b

Creatinine (0-1.5 mg/dL)b Urinalysisa

Proteinuria (dipstick) Hematuria (dipstick) Pyuria (N5/HPF)

12904.7 F 4771.6

76.6 F 10.7

812.1 F 569.4

2.9 F 3.9

60.3 F 34.3

50.3 F 26.3

78.9 F 20.8

19.8 F 6.0

1.3 F 0.3

16 (80%)

9 (45%)

3 (15%)

WBC indicates white blood cell; AST, aspartate aminotransferase; ALT,

alanine aminotransferase; ALP, alkaline phosphatase; CRP, C-reactive protein; BUN, blood urea nitrogen; HPF, high-power field.

a Number (%).

b Mean F SD.

c The serum LDH level was ordered initially in 5 patients before the diagnosis of renal infarction. However, it was checked in all study patients within 24 hours after ED visit.

Abdominal pain/tenderness

17 (85%)

Flank pain/tenderness

17 (85%)

Back pain/tenderness

2 (10%)

Nausea/vomiting

3 (15%)

Fever/chills

1 (5%)

Nineteen patients (95%) received analgesics for pain control, but all had a poor response before the start of anticoagulant or thrombolytic therapy. It took a mean of

66.8 hours to control pain after anticoagulant or thrombo- lytic therapy (Table 3). The evaluation of pain under control was based on the chart record, which documented the flank and/or abdominal pain subsided from subjective patient’s description or objective physician’s examination. All

20 patients received medical treatment with coumadin, which was given in combination with heparin in 12 patients, with peripheral intravenous and/or local intra-arterial thrombolytics with urokinase in 5, and with mitral valve replacement in 1. Four patients, who were all revisiting cases, had new onset of renal impairment initially with a mean F SD serum creatinine level of 1.75 F 0.17 mg/dL. Renal function did not recover or worsen during more than 1 year of follow-up after discharge in 3 patients, one of whom had received urokinase and coumadin. No patient died or needed dialysis during hospitalization.

Normal ordered laboratory datab

10 (100%)

Subjectively partial pain control by medications

9 (90%)

Impression of urolithiasisc

8 (80%)

Impression of Peptic ulcer disease

1 (10%)

Impression of stool impaction, relieved by enema

1 (10%)

There may be multiple reasons accounting for the Delay in diagnosis in 10 patients (Table 4). Accordingly, emer- gency physicians (EPs) may have considered that these patients had clinical presentations suggestive of urolithiasis or other common gastrointestinal diseases. To investigate whether there existed clinical factors that were predictive of an early diagnosis of renal infarction, we compared all the parameters between 10 early-diagnosed patients and 10 delayed-diagnosed patients. No statistically significant differences were noted.

Discussion

The actual incidence of renal infarction is still unknown. Lessman et al [7] reported on 17 patients during a period of

14 years from either clinical practice or autopsy. An estimated incidence of 0.007% (17 of 248842) was found

in a previous report [1] and 0.004% (20 of 481540) in the current study at a single ED setting. Based on the relative lower incidence compared with other intra-abdominal conditions that can mimic renal infarction (eg, urolithiasis), EPs will probably only encounter less than 10 patients with acute renal infarction throughout decades of clinical practice. Nevertheless, if the correct diagnosis cannot be made earlier, it can result in a certain degree of comorbidity or even mortality in those patients who have Multiple organ dysfunction [4].

The clinical characteristics of the 20 patients in this study, including age, previous thromboembolic events, side of infarction, and clinical symptoms and signs, were comparable with those in previous case-series studies [1,4,6,7]. The important laboratory findings that referred to renal infarction have included positive findings of blood in urine in 53.8% to 100% of patients, elevated serum LDH level in 81.8% to 100% of patients, and serum creatinine level greater than 1.5 mg/dL in 27.2% to 88.2% of patients. We compared the initial clinical presentations and routine laboratory results between 10 patients with early diagnosis and 10 patients with delayed (revisit) diagnosis. No statistically significant difference was identified for any of the parameters. Domanovits et al [1] suggested that for all

patients presenting with the triad–high risk of thrombo- embolic event, persisting flank/abdominal/back pain, ele- vated serum levels of LDH and/or hematuria within 24 hours after pain onset–CT should be performed to detect possible renal infarction or other abdominal lesions. In our study, we found 16 patients (80%) had the triad of persisting flank or abdominal pain/tenderness, elevated LDH level, and pro- teinuria. If we use hematuria to replace proteinuria in this triad, however, only 9 patients (45%) cohere with it.

The key step for achieving an early diagnosis of renal infarction is that EPs have high alertness with regard to ordering determinate imaging studies, that is, a contrast- enhanced CT to differentiate renal infarction from other diseases that clinically mimic renal infarction based on clinical presentations. The imaging tools that have been reported in previous articles to have been used for the

Table 4 Reasons for delay in diagnosis of 10 patients with

renal infarction at First visita

a Number (%). Some patients had multiple reasons.

b Normal laboratory data including complete blood count, urinal- ysis, and liver panel, but no serum lactate dehydrogenase data.

c No hematuria or pyuria was noted in 7 patients. All the 8 patients did not have visible stones on kidney-ureter-bladder radiographs.

Fig. 1 Contrast-enhanced CT scan of a 49-year-old man with atrial fibrillation and sudden-onset bilateral flank pain showed multiple wedge-shaped hypodense lesions (arrow head) over bilateral kidneys (A) and spleen (B) in favor of infarction in bilateral kidneys and spleen.

Fig. 2 Proposed diagnostic flowchart for patients with suspected renal infarction.

diagnosis of renal infarction include angiography [7], Doppler sonography [16], CT scan of the abdomen [1,4,6], renal isotope scan [4,7], and excretory urography [7]. Angiography is the criterion standard for diagnosing acute renal infarction. Although unenhanced helical CT is now considered to be the investigation tool of choice for the diagnosis of renal colic [14], it cannot easily detect renal artery or venous thromboembolism. Contrast-enhanced CT, which has several advantages including a great improve- ment in technology for easy interpretation and detection of other retroperitoneal or intraperitoneal adjacent lesions, as well as being noninvasive and potentially available 24 hours a day, has been regarded as having an acceptable capability for the diagnosis of acute renal infarction in ED use [1,4,6]. In addition to differentiating abscess, cyst, tumor, or adjacent lesions around the kidney, it may also detect extrarenal causes of acute abdominal pain including appendicitis, leaking aortic aneurysm, Biliary tract diseases, diverticulitis, and gynecologic disease.

All 20 cases in this study had the classic finding of a wedge-shaped zone of peripheral diminished density

without Contrast enhancement (Fig. 1). No recognizable false-negative or associated tumor was found in any of our patients during hospitalization and follow-up. In this study, we advocated that in those patients with clinical presentation suggestive of high probability of renal infarction, unen- hanced CT scans of the abdomen should be followed by enhanced scans if no calculi are detected. We made the correct diagnosis of renal infarction in 10 of 20 patients (50%) at the time of their first visit to our ED. To our knowledge, this result is higher than previous reports that range from 0% to 40.5% at admission [1,4,6,7]. Accord- ingly, to enhance alertness or understanding with regard to this uncommon disease, we propose a diagnostic flow chart as a practical and effective method that may help the EP to diagnose patients with renal infarction earlier (Fig. 2).

The management of renal infarction remains controver- sial. Recent case-series studies have demonstrated that medical management with anticoagulants and/or intrave- nous or intra-arterial thrombolytics is feasible, with success obtained in most cases [1,4,6]. Our results showed that anticoagulant and/or thrombolytic therapy provided favor- able outcomes with good recovery of renal function in 17 patients (85%) and no need for dialysis in 3 patients with Chronic renal insufficiency during hospitalization and more than 1 year of follow-up. In terms of the recovery of normal renal function as the outcome assessment of treatment programs, 4 patients who received intrarenal or intravenous thrombolytics and anticoagulants did not show a better outcome than those receiving anticoagulants only. This finding may be attributed to those patients being diagnosed too late to have better response to thrombolytic therapy, which cannot reverse insult from prolonged renal ischemia. Given that renal impairment may correlate with a no-flow period in the renal artery, the duration from initial symptoms and signs to definite diagnosis may be a major factor in predicting renal outcomes. A trend of increase in mean serum urea level was reported by Hanznov et al [4] when the diagnosis of renal embolus was made on admission or the first hospital day, with the concentration increasing from 59.9 F 50.2 to 89.6 F 107.2 mg/dL on day 3. There was no significant difference in serum urea level at discharge between those patients whose diagnosis was made on the first hospital day and those whose diagnosis was made on subsequent days. This does not imply that an early diagnosis is not mandatory for the preservation of renal infarction. Potentially, chronic renal failure or even mortality may occur in patients with Multiple comorbidities if the correct diagnosis is not made soon enough. In this study, the 4 patients with renal impairment did not experience a longer time in the ED workup for a definite diagnosis of renal infarction than those with normal renal function. However, 3 patients with persistent renal impairment all had a delayed diagnosis. Among these patients, one had bilateral renal infarction and another had splenic infarction concomitantly without improvement by thrombolytic therapy. It follows that both

the duration and range of infarction are major factors closely related to subsequent renal function.

Limitations

There are several limitations of this investigation. First, data were collected from a retrospective chart review; and some clinical presentations or records may not have been documented completely. Second, in patient selection, many hospitalized patients with life-threatening cardiovascular diseases or systemic diseases at the time of diagnosis of renal infarction were excluded to clarify the initial clinical characteristics of this entity. We therefore may have neglected renal infarction as a potential sequelae or complication from other systemic diseases. Third, patients with a false-negative result for renal infarction that was undetected by contrast-enhanced CT or other imaging studies may not have been recruited in this study. Furthermore, we did not use the criterion standard investi- gation of renal artery angiography for diagnosis of renal infarction in this study. However, with the improvement in CT technology (especially in spiral CT) in recent years, the accuracy in the diagnosis of renal infarction by contrast- enhanced CT has been accepted and applied in recent studies [1,4,6,15].

Conclusions

In conclusion, we delineated the initial clinical character- istics of 20 patients with acute renal infarction who presented at a single ED setting at a medical center over the past 10 years. The predominate clinical features of these patients included old age, risk factors for thromboembolism, sudden onset of abdominal or flank pain, elevated serum LDH level, and proteinuria. Contrast-enhanced CT was used to make a Prompt diagnosis of renal infarction. Anti- coagulants, coumadin only or with heparin, provided

favorable outcomes, as did additional thrombolytics, for treatment of all study patients. That the recovery of renal function cannot be achieved by using these standard treatment modalities for all patients may emphasize the other imperative component, an early diagnosis, for a better prognosis of this disease.

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