Does Microscopic Hematuria After Pediatric Blunt Trauma Indicate Clinically Significant Injury?

BACKGROUND: Children are more likely to have urinary system injury after blunt abdominal trauma (BAT) because of anatomical vulnerabilities. Urinalysis (UA) is often performed during initial evaluation to screen for injury. The purpose of this study was to determine how often finding microscopic hematuria after BAT leads to further testing and whether this indicates a significant injury. METHODS: A retrospective review of children evaluated for BAT at Children's Health from 2013 to 2017 was performed. Patients included had microscopic hematuria on initial UA. Data collected included demographics, injury data, laboratory and imaging data, and outcomes. Analysis was performed using descriptive statistics, Fisher's exact, and independent t-test. RESULTS: Of 1059 patients treated for BAT during the study period, 203 (19%) exhibited microscopic hematuria on UA during the initial workup. Most UAs resulted after imaging was completed and did not impact management (158, 78%); twenty-two (14%) of these patients had urinary injury, which were diagnosed by imaging regardless of UA results. Forty-five (22%) patients were found to have microscopic hematuria that independently led to workup for urinary injury. Of these, nine patients had a urinary system injury: 6 low-grade renal and three bladder wall injuries, none of which required surgery. Those with and without urinary injury in this group underwent similar numbers of radiographic studies. CONCLUSIONS: Microscopic hematuria on screening UA after BAT may lead to extensive workup, regardless of the presence of symptoms. In patients who receive cross-sectional abdominal imaging, preceding UA adds little to the clinical workup of children with BAT.

Assessment of urinary dipstick in patients admitted to an ED for blunt abdominal trauma.

INTRODUCTION: Clinicians still face significant challenge in predicting intra-abdominal injuries in patients admitted to an emergency department for blunt abdominal trauma. This study was thus designed to investigate the value of dipstick urinalysis in patients with blunt abdominal trauma. METHODS: We performed a retrospective, multicenter, cohort study involving patients admitted to the emergency department for abdominal traumas, examined by means of urinary dipstick and abdominal CT scan. The primary endpoint was the correlation between microscopic hematuria detected via dipstick urinalysis (defined by the presence of blood on the dipstick urinalysis but without gross hematuria) and abdominal injury, as evidenced on CT scan. RESULTS: Of the 100 included patients, 56 experienced microscopic hematuria, 17 gross hematuria, and 44 no hematuria. Patients with abdominal injury were more likely to present with hypovolemic shock (odds ratio [OR]: 8.4; 95% confidence interval [CI]: 2.7-26), abdominal wall hematoma (OR: 3.1; 95% CI: 1.2-7.9), abdominal defense (OR: 5.2; 95% CI: 1.8-14.5), or anemia (OR: 3.6; 95% CI: 1.2-10.3). Moreover, dipstick urinalysis was less likely to predict injury, with just 72.2% sensitivity (95% CI: 54.8-85.8), 53.1% specificity (95% CI: 40.2-65.7), and positive and negative predictive values of 46.4% (95% CI: 33.0-60.3) and 77.3% (95% CI: 62.2-88.5), respectively. CONCLUSION: Dipstick urinalysis was neither adequately specific nor sensitive for predicting abdominal injury and should thus not be used as a key assessment component in patients suffering from blunt abdominal trauma, with physical exam and vital sign assessment the preferred choice.

A negative urinalysis is associated with a low likelihood of intra-abdominal injury after blunt abdominal trauma.

BACKGROUND: The utility of urinalysis (UA) to diagnose intra-abdominal (IA) or genitourinary (GU) injury after blunt trauma remains controversial. The purpose of this study was to determine the significance of UA in the blunt trauma patient. METHODS: A retrospective review of patients admitted for blunt abdominal trauma from 2011 to 2013. RESULTS: A total of 1,795 patients sustained blunt abdominal trauma: mean age of 44 ± 21 years; mean Injury Severity Score of 13 ± 10. Overall 810 patients had a negative UA (45%). Two patients (2/810 and .2%) had a GU injury and neither required intervention. Thirty-two patients (32/810 and 4.0%) had an IA injury, and 2 (2/810 and .02%) required intervention. The sensitivity for predicting GU injury requiring intervention was 1, and IA injury requiring intervention was .96. Negative predictive values were 1 and .99. CONCLUSIONS: A negative UA correlates with a low risk for GU and IA injury after blunt abdominal trauma. A negative UA should be evaluated prospectively as part of a clinical prediction score to rule out injury and avoid unnecessary radiation exposure from computed tomography imaging.

Routine urinalysis in patients with a blunt abdominal trauma mechanism is not valuable to detect urogenital injury.

OBJECTIVE: To investigate whether the routine performance of urinalysis in patients with a blunt trauma mechanism is still valuable. METHODS: Consecutive patients aged ≥16 years, admitted to a Dutch Level 1 trauma centre between January 2008 and August 2011, were included in this retrospective cohort study. Results of urinalysis (erythrocytes per µL) were divided into no, microscopic or macroscopic haematuria. Patients were divided into four groups based on whether a urinalysis was performed or not, with or without imaging for urogenital injury. Main outcome measures were the presence of urogenital injury and whether the findings on urine specimen and/or imaging led to clinical consequences. RESULTS: A total of 1815 patients were included. The prevalence of intra-abdominal and urogenital injuries was 13% and 8%, respectively. In 1363 patients (75%), urinalysis was performed and 1031 patients (57%) underwent imaging for urogenital injury as well. The presence of macroscopic haematuria (n=16) led to clinical consequences in 73% of the patients (11 out of 15), regardless of the findings on imaging. Microscopic haematuria on urinalysis in combination with no findings on imaging led to clinical consequences in 8 out of 212 patients (4%). Microscopic haematuria on urinalysis in patients who did not have imaging for urogenital injury did not lead to clinical consequences (0 out of 54 patients; 0%). All the 8 patients who underwent an intervention had positive findings on imaging. CONCLUSIONS: The results do not support the routine performance of urinalysis in patients admitted with a blunt trauma mechanism. Although urinalysis could be valuable in specific patient populations, we should consider omitting this investigation as a routine part of the assessment of trauma patients.

Microscopic hematuria as a marker of blunt abdominal trauma in rats: description of an experimental model.

BACKGROUND: Microscopic hematuria is an extremely important sign in blunt abdominal trauma (BAT) patients. Controversies still exist in the literature on whether microscopic hematuria is a sign of intra-abdominal extrarenal organ injury and is an indication for radiographic assessment of BAT patients. In this study, a new BAT rat model was developed, and we tried to determine the relationships between microscopic hematuria and extrarenal intra-abdominal organ injury. METHODS: After verifying our model, lethal and maximal sublethal intensity of impact energy determined in the rats. Animals allocated into six sublethal impact energy groups. BAT was induced by dropping a standard mass from variable heights. After 2 hours of examining period, macroscopic laparotomy findings, histopathological liver, spleen and renal injury grades, and microscopic hematuria levels were recorded in these six groups. RESULTS: According to our results, while the trauma intensity increase severity of the histopathological injury increases for all organs. Although there was a significant correlation between microscopic hematuria and trauma intensity, we could not show same relationship between microscopic hematuria and histopathological organ injury. On the other hand, microscopic hematuria was correlated with the macroscopic laparotomy findings. CONCLUSIONS: Microscopic hematuria could serve as a predictor of the severity of trauma and intra-abdominal organ injury. This study would support the use of abdominal imaging and attentive assessment for intra-abdominal organ injury in stable BAT patients with hematuria. The laparotomy threshold may be lowered for unstable BAT patients with hematuria.

Determination of urinary N-acetyl-ß-D glucosaminidase (NAG) levels in experimental blunt renal trauma.

BACKGROUND: We evaluated the applicability of urinary N-acetyl-beta-D glucosaminidase (NAG) levels in the diagnosis and follow-up in blunt kidney injury. METHODS: Twenty Sprague-Dawley rats were studied. In the Sham group, left kidney exploration was made. In the Trauma group, after left kidney exploration, a 20 g weight was dropped onto the kidneys. Urine was collected for analysis with strip and determination of urinary NAG and creatinine (Cr) levels at baseline and 0-6, 12-24, 24-36 and 36-48 postoperative hours. Mann-Whitney U and Kruskal-Wallis tests were used. RESULTS: Macroscopic examinations of traumatized kidneys revealed grade II and III injury, and histopathological examinations showed relevant changes. Macroscopic hematuria was observed in all traumatized rats. Urinary NAG/Cr levels in the Trauma group were found to be significantly higher than their base levels at 0-6, 12-24, 24-36, and 36-48 hours. In the Sham group, only the level of NAG/Cr at 0-6 hours was significantly higher. The increase in NAG/Cr levels at 0-6 hours was significantly higher in the Trauma group than in the Sham group. CONCLUSION: After isolated blunt renal trauma, urinary NAG levels increase in the early stage. However, more detailed clinical studies are needed to develop NAG levels as a criterion in the follow-up of blunt renal trauma.

Prospective comparison of microscopic and gross hematuria as predictors of bladder injury in blunt trauma.

OBJECTIVES: The evaluation of the genitourinary system in patients with blunt trauma remains controversial. Historically, patients with more than 50 red blood cells on urinalysis underwent additional genitourinary imaging. Retrospective studies have demonstrated that bladder injury is almost always associated with gross hematuria. We have prospectively demonstrated that bladder imaging is required for gross hematuria and unnecessary for microscopic hematuria. METHODS: Patients sustaining blunt trauma with hematuria were prospectively evaluated during a 3-year period. During the first 18 months of the study (first treatment arm), patients with microscopic hematuria (more than 50 red blood cells on urinalysis) underwent bladder imaging. During the second 18 months, patients underwent bladder imaging only for gross hematuria. RESULTS: A total of 8026 patients were evaluated. In the first arm, 214 patients underwent cystography for microscopic hematuria, and no bladder injuries were identified; 78 patients underwent cystography for gross hematuria, and 21 bladder injuries were identified. Chi-square analysis revealed no difference in the presence of microscopic hematuria to predict for bladder injury. In the second arm, 308 patients presented with microscopic hematuria, none of whom underwent cystography, and 91 patients underwent cystography for gross hematuria, with 15 bladder injuries identified. The presence of gross hematuria demonstrated 100% sensitivity and 98.5% specificity as a screening test for bladder injury. No bladder injuries were missed. CONCLUSIONS: The results of our study have shown that the presence of gross hematuria warrants evaluation of the bladder. The presence of gross hematuria demonstrated improved sensitivity, specificity, positive predictive value, negative predictive value, and accuracy over the presence of microscopic hematuria in the detection of bladder injury. Using gross hematuria as an indication for bladder imaging will eliminate unnecessary imaging without compromising the quality of patient care.

Prediction of posttraumatic adult respiratory distress syndrome by albumin excretion rate eight hours after admission.

BACKGROUND: Adult respiratory distress syndrome (ARDS) in trauma victims carries a mortality on the order of 50%. An early feature is an increased capillary permeability causing an extravasation of plasma proteins and water, leading to interstitial edema. In the kidney, the increase in microvascular permeability is manifested as increased albumin excretion detectable by sensitive immunoassay. METHODS: Forty seven trauma victims were studied for 5 days; 32 of them had Injury Severity Scores > 18. A diagnosis of ARDS was made on the recommendations of the American-European Consensus Conference on ARDS (1994). Eight patients developed ARDS, five developed pulmonary dysfunction, and the remainder showed no significant pulmonary abnormality. RESULTS: Using the near patient urine albumin immunoassay, albumin excretion rate (AER) was measured after admission. For patients with Injury Severity Score > 18, the median (95% confidence interval) AER 8 hours after admission was 63 (range, 40-99) microg per minute for those without impaired lung function and 339 (range, 162-454) microg per minute for those in the combined ARDS and pulmonary dysfunction group (Mann-Whitney test, p = 0.0004). The median AER was 51 (range, 27-98) microg per minute for patients with Injury Severity Score < 18. The positive predictive value for the development of ARDS or pulmonary dysfunction of AER > 130 microg per minute was 85%, with a negative predictive value of 95%. CONCLUSIONS: These data indicate that the capillary leak associated with the subsequent development of pulmonary dysfunction and ARDS can be detected within 8 hours of admission at the patient's bedside, thus providing a means of early identification of patients at greatest risk and allowing for early intervention.

Radiographic assessment of blunt renal trauma.

Recent reports in the urologic literature suggest that radiographic evaluation of normotensive blunt trauma patients with microscopic hematuria is no longer necessary. Several facilities, however, including the Los Angeles County-University of Southern California Medical Center continue to routinely perform intravenous pyelography in this setting. To further evaluate whether this practice is indicated, we retrospectively reviewed the records of 337 patients seen at our facility between May, 1986 and December, 1989 following blunt trauma with resultant microscopic hematuria but no shock. All patients were radiographically assessed with an intravenous pyelogram. Of the 337 studies, 30 (9%) had an abnormal result, including 28 renal contusions, 1 ureteropelvic junction (UPJ) disruption, and 1 non-functioning kidney (which on further evaluation revealed a congenitally absent kidney). A total of 1 significant urologic injury was identified. Thus, only one injury (0.3%) would have been missed if a policy of observation was followed in this group of patients. Our data support other reports in the urologic literature that radiographic staging is not necessary in managing blunt trauma patients with microscopic hematuria but no shock.

Emergency center laboratory evaluation of pediatric trauma victims.

Emergency center (ER) trauma evaluations often include leukocyte count (LC), serum amylase (SA), electrolytes (EL), and urine analysis. We reviewed records of 100 pediatric ER patients to determine utility of these tests in management of blunt injury. SA was evaluated in 65 patients and ranged from 30-146 U/L (mean 50.6 U/L); 14 patients with normal CT scans had SA from 30-68 U/L (mean 49.1 U/L). Six patients with intraabdominal or retroperitoneal injuries had SA from 30-130 U/L (mean 64.0 U/L), P = NS. LC was determined in 76 patients and ranged 2.3-28.3 k/ml (mean 13.8 k/ml). Patients with normal abdominal CT (12) had mean LC 14.8 k/ml (range 7.2-19.6 k/ml). Eight patients with injuries on CT had mean LC 14.4 k/ml (range 3.5-27.1 k/ml). ER, SA, and LC did not alter patient management. Thirty-four patients had serum sodium, 36 potassium, and 33 chloride and bicarbonate determinations. Sodium, potassium, and chloride levels were uniformly normal; bicarbonate and leukocyte counts were uniformly abnormal in initial evaluations. These changes are expected in response to severe injury and their determinations did not alter patient care. Combined laboratory urinarlysis (LA) and urine dipstick (DA) analysis for hematuria had sensitivity 75.0 per cent (specificity 81.6%). LA predicted injury with sensitivity 75.0 per cent (specificity 81.6%). DA predicted injury with sensitivity 60.0 per cent (specificity 79.2%). DA accurately represented LA results (sensitivity 100%, specificity of 94.5%). DA is a rapid and effective replacement of LA in evaluation of trauma patients in the emergency center.

Urinary lactic dehydrogenase as a marker of renal injury in blunt trauma patients with hematuria.

We evaluated the use of urinary lactic dehydrogenase (LDH) in predicting renal injury in a convenience sample of 36 blunt trauma patients with hematuria. The mean +/- SEM urinary LDH for the five patients with renal injuries was 129.4 +/- 35 U/L, which was not significantly different from the mean urinary LDH levels in either the 22 patients without demonstrable genitourinary or retroperitoneal injuries (92.9 +/- 20.7 U/L) or the nine patients with nonrenal genitourinary or retroperitoneal injuries (165 +/- 46 U/L). Urinary LDH at a threshold of 135 U/L was more specific (75% vs 53%, P less than .01) and more accurate (74% vs 57%, P less than .01) than hematuria at a threshold of 50 red blood cells per high-power field in predicting lacerations of the kidney or ureter; urinary LDH was less sensitive than hematuria at these thresholds (67% vs 100%), but not significantly. We conclude that urinary LDH is a nonspecific marker of cellular disruption anywhere along the genitourinary tract in otherwise healthy blunt trauma patients.

Detection and significance of microscopic hematuria in patients with blunt renal trauma.

Detection of hematuria is paramount in establishing injury to the urinary system. In 339 patients with blunt renal trauma in whom radiographic studies defined the severity of injury we compared the degree of microscopic hematuria determined by dipstick and microscopic urinalysis. The overall correlation between the 2 methods was low (Pearson's coefficient 0.41). However, more than 80 per cent of the urine samples with 50 to 100 red blood cells per high power field corresponded to a dipstick result of 3+. The dipstick method had greater than 97.5 per cent sensitivity and specificity for detection of microscopic hematuria. Only 7 of the 339 patients (less than 2 per cent) had a discharge diagnosis of other than renal contusion: 5 had renal artery thrombosis or avulsion of the renal vessels and 2 had minor cortical lacerations that were managed nonoperatively. Although microscopic hematuria may be quantified more accurately by microscopic analysis, it can be detected reliably with a high degree of sensitivity and specificity by dipstick analysis.

Urine dipstick vs. microscopic urinalysis in the evaluation of abdominal trauma.

This study was designed to assess the accuracy of the urine dipstick and its ability to predict injury to the urinary tract when compared to routine urinalysis: 1,485 patients had dipstick and microscopic urinalysis performed as part of their evaluation for blunt and penetrating trauma. Dipstick analysis was recorded as either positive or negative. Microhematuria was defined as greater than 0-1 RBC/HPF on microscopic analysis. Blunt trauma accounted for 1,347 (91%) of the patients and penetrating injuries accounted for 138 cases (9%): 1,209 (81.4%) of the specimens were dipstick negative, and 276 (18.6%) were dipstick positive. False negative results, consisting of a negative dipstick reading and greater than 1 RBC/HPF on microscopic analysis occurred in 100 (6.9%) of the cases. False positive dipstick readings occurred in 64 (4.3%) of the patients. There were no cases of a missed injury in the group of 100 false negatives. Cost savings by conversion to the use of dipsticks would have saved our institution about $63,000 per year. It is concluded that the urinary dipstick is a safe, accurate, and reliable screening test for the presence or absence of hematuria in patients sustaining either blunt or penetrating abdominal trauma.

Comparison of IVP and CT findings in patients with suspected severe renal injury.

Excretory urography (IVP) is the primary diagnostic tool for renal injury but has been indeterminate in diagnosing severe renal injuries in most cases. Computed tomography (CT) provides precise anatomic detail of renal injuries. The IVP and CT findings were compared in 22 patients with suspected severe renal injuries suggested by clinical examination and initial screening IVP. CT provided determinate diagnoses in all the cases of severe renal injury, while the IVP diagnoses were indeterminate in 82 per cent of these cases. Although clarification is needed on the accuracy of CT in diagnosing renal vascular injury, the CT diagnoses were accurate in all other types of severe renal injury (as well as minor renal injuries).