Article, Traumatology

Combination of white blood cell count with liver enzymes in the diagnosis of blunt liver laceration

Original Contribution

Combination of white blood cell count with liver enzymes in the diagnosis of blunt Liver laceration

Wei-Che Lee MD a,b,c, Liang-Chi Kuo MD a,b, Yuan-Chia Cheng MD a,b, Chao-Wen Chen MD a,b,c, Yen-Ko Lin MD a,b,

Tsung-Ying Lin MD a,b, Hsing-Lin Lin MD a,b,c,d,?

aDepartment of Trauma, Kaohsiung Medical university hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan

bDepartment of Emergency Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University,

Kaohsiung 807, Taiwan

cDepartment of Surgery, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan

dGraduate Institute of Healthcare Administration, Kaohsiung Medical University, Kaohsiung 807, Taiwan

Received 28 March 2009; revised 31 May 2009; accepted 8 June 2009

Abstract

Background: It is sometimes difficult to decide whether to perform abdominal computed tomographic scans for possible liver laceration in patients who have sustained less severe or minor blunt abdominal trauma. This study was conducted to find out whether the basic laboratory workup could provide information of possible liver laceration in blunt abdominal trauma patients and act as an indication for CT scans.

Methods: In this retrospective case-control study, we included 289 patients who had sustained blunt Abdominal injury for which they received abdominal CT scans in our emergency department. Of the 289 patients, the study group (n = 42) included patients who had been found to have liver lacerations after obtaining the CT; the controls (n = 42) were those not found to have such injuries by the same method with matching of age and sex.

Results: In patients with blunt abdominal injuries, there is a strong difference in liver laceration between elevation of white blood cell counts (P = .001), aspartate aminotransferase (P b .001), and alanine aminotransferase (ALT) (P b .001). A logistic regression model demonstrated that WBC count and AST were independently associated with liver laceration. With elevations of serum AST greater than 100 IU/L, ALT greater than 80 IU/L, and WBC count greater than 10 000/mm3, we found a sensitivity and specificity of 90.0% and 92.3%, respectively, in the 42 liver laceration victims.

ConclusionIn patients with blunt abdominal trauma, elevated WBC counts together with elevated ASTand ALT are strongly associated with liver laceration and warrant further imaging studies and management.

(C) 2010

* Corresponding author. Department of Trauma, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan. Tel.: +886 73125895×7553; fax: +886 73208255.

E-mail addresses: [email protected] (W.-C. Lee), [email protected] (L.-C. Kuo), [email protected] (Y.-C. Cheng), [email protected] (C.-W. Chen), [email protected] (Y.-K. Lin), [email protected] (T.-Y. Lin), [email protected] (H.-L. Lin).

Introduction

In trauma patients, when blunt abdominal injuries occur, the liver is the second most commonly injured organ [1]. When patients present with less significant or occult blunt abdominal trauma in an emergency department (ED), it is

0735-6757/$ – see front matter (C) 2010 doi:10.1016/j.ajem.2009.06.005

sometimes difficult to determine whether further examina- tion is needed to diagnosis whether there is liver laceration. Although right upper quadrant pain during physical examination may indicate Hepatic injury in conscious patients, this is still a fairly unreliable indicator of injury even in skilled and experienced hands [1-6]. Focused abdominal sonography for trauma (FAST) can sensitively detect free fluid in the abdomen and pelvis [7-9]. However, the positive rate is about 64% sensitivity for documented injuries in a previous study [10]. When there are parench- ymal injuries of liver only, with no free fluid, the sensitivity will be even lower [2]. Therefore, routine abdominal Computed tomographic scans have been suggested for hemodynamic stable patients with suspicious blunt

abdominal trauma [11].

In Taiwan and throughout many Western Counties, most patients with abdominal injuries arrive at the EDs of district general hospitals that are equipped with CT. However, in many parts of the world, CT scanning is readily available in urban areas but not in rural and remote areas–for example, Australia, Africa, and India have substantial variability in the distance to CT facilities [12]. In addition, considering the potential risks carried in the CT Imaging study, including possible renal toxicity of and allergic reaction to the contrast or the potentially adverse effect of the radiation dosage, especially in a pregnant woman, it is difficult to determine whether obtaining CT scans in these patients is advisable. Therefore, it would be desirable to identify some factors that can help to make this decision and initiate prompt treatment of abdominal injury.

Various pediatric studies have investigated the association between liver enzymes and hepatic injuries [13-16]. Another study found an association between WBC count and intraabdominal injury [17]. However, WBC count is considered to be nonspecific and has never been described as a possible diagnostic indicator of liver laceration.

Combining hepatic enzymes and WBC counts to predict hepatic injury is common practice among pediatric surgeons and by some adult trauma surgeons as well. However, the relevance of these is that this known clinical observation has not had significant published data to support it. Therefore, we retrospectively reviewed liver laceration patients and analyzed the differences of WBC counts and hepatic enzymes in the initial laboratory workup. We attempted to make clear whether WBC counts could help predict liver laceration when used in conjunction with liver enzymes.

Materials and methods

Study design

In this retrospective case-control study, we studied the records of all visitors to the ED for blunt abdominal injuries generated from our trauma registry. The data were collected

from a 1200-bed hospital in southern Taiwan and were reviewed. The study hospital is a university teaching hospital that provides health care service to approximately 1.5 million people within the Kaohsiung metropolitan area and has more than 80 000 visits to the ED annually. Although fully equipped with level I trauma center facilities, the victims sent to the study hospital had a wide range of trauma triage status due to lack of strict dispatch policy, as trauma surgeons at the scene were occupied by patients from less severe trauma to Serious injuries. Therefore, our trauma patients varied widely. Before the study, the protocol was approved by the institutional review board of the study hospital.

Data collection and processing

This study included all patients who were sent to our ED with blunt abdominal injury. Starting from arrival, all patients were treated by 1 of the 4 trauma surgeons in our ED. Abdominal CT scans were performed when there was

(1) severe and persistent right upper quadrant pain of the abdomen, (2) intraabdominal fluid found by FAST, (3) unstable vital signs with any suspicion of intraabdominal injury, or (4) high-risk mechanism as judged by the attending trauma surgeon.

We aggregated data surveys between January 1, 2005, and August 31, 2008, for patients who had blunt abdominal contusion accidents and were sent to our ED having their Blood drawn within 6 hours. The studied patients were initially given a diagnosis of blunt abdominal injury upon admission to our ED and underwent abdominal CT scans for detection of intraabdominal injury. Case and control patients (patients with abdominal trauma without liver laceration) were age, sex, and vital signs matched 1:1 for the same period. Patient data were collected from various medical records, including physician, nurse, and emergency medical technician records and records of laboratory and imaging studies. Data collection forms also included trauma mechan- isms, disposition, and follow-up after discharge. Although a junior trauma surgeon reviewed the medical chart, a senior trauma surgeon supervised and reviewed the data for completeness for double checking. Liver laceration was diagnosed and graded by an abdominal CT scan, reported by a radiologist and confirmed by the senior trauma surgeon. If the diagnosis and grade assigned by these 2 experts did not match, then the CT was reevaluated for consensus.

Vital signs, including pulse rate, respiratory rate, and blood pressure, were taken on arrival at the ED. All laboratory data, including aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatinine clearance, blood urea nitrogen, and complete blood cell counts, were collected. Liver laceration was diagnosed and graded by CT scans.

Patients were excluded if they had Traumatic cardiac arrest or had profound shock on arrival, had been transferred from other hospitals after primary treatment, or had concomitant other major trauma that warranted transfusion or further

Variables

Liver laceration (n = 42)

Control (n = 42)

P

Age (y)

34.79 +- 19.02

33.63 +- 18.43

.801a

Female

24

28

.069b

Systolic blood

122 +- 22

132 +- 25

.135a

pressure

Diastolic blood

76 +- 18

81 +- 17

.212a

pressure

Heart rate

91 +- 23

89 +- 18

.641a

Temperature

36.3 +- 1.0

36.7 +- 0.7

.066a

WBC

12 996 +- 5.724

8.573 +- 3.751

.001a

AST

375 +- 311

95 +- 160

b.001a

ALT

287 +- 238

74 +- 125

b.001a

P values are based on the Student t testa and ?2 testb.

management rather than intraabdominal injury. Patients who left the hospital against medical advice, had missing medical records, had a medical history of hepatitis, and did not have blood drawn more than 6 hours after trauma were also excluded. All patients having liver laceration were admitted to our hospital and those who had sustained blunt abdominal contusion if discharged from our ED were asked to follow-up at trauma outpatient clinic in our hospital 3 days later for a double check.

Table 1 Demographics and averaged physiologic parameters and variables in both groups

The grade of liver laceration was determined by CT scans based on the criteria established by the American Associa- tion for the Surgery of Trauma Organ Injury Scale for Hepatic Injuries [18]. Since reporting our data, there have been no changes to our working protocols for patients with suspected liver injuries based upon abnormal enzymatic findings. However, some patients with normal liver enzymes would have CT scans if the trauma surgeons had any suspicions of liver laceration.

Primary data analysis

Mean and SD were calculated for continuous variables. ?2 test and Student t test were used to evaluate the association between various categorical and continuous variables. One-way analysis of variance was used to analyze the difference of variables by laceration grade. Binary logistic regression analysis with “forward: conditional” model was used to identify which variables were predictive of liver laceration. Odds ratios were calculated by logistic

regression. All P values were 2-sided and considered significant at P b .05. All statistical operations were performed using SPSS 14.0 for Windows (SPSS Inc, Chicago, Ill).

Results

Characteristics of study sample

In total, during the study period, 289 patients were admitted to our ED and received enhanced abdominal CT scans. Forty-two of these patients were diagnosed as having liver laceration at discharge and could not be excluded for any of the reasons described above. These 42 patients were assigned to the study group, which consisted of Males and females ranging equally in age from 3 to 91 years old. The controls were recruited from the same 289 patients admitted for abdominal blunt trauma, having no liver laceration when examined by CT scans. As can be seen from (Table 1), the 2 groups were matched with respect to sex and age, and there were also no significant group differences in clinical characteristics including systolic and diastolic blood pres- sures, heart rate, and body temperature.

Main results

Compared to the controls, patients with liver lacerations had significantly higher WBC counts (P = .001), AST (P b

.001), and ALT (P b .001) (Table 1). In the group with liver lacerations, the greater the severity of laceration, the greater was the WBC count (mean of WBC count from grades I to V, 10 913/mm3, 15 375/mm3, 12 946/mm3, 12 366/mm3, and 28 670/mm3, respectively).

In the study group, the grades of liver laceration (from I to V) were significantly different in AST (P = .002) and WBC (P = .003) but not ALT (P = .144). Nevertheless, in general, the more severe the laceration, the greater would be the level of hepatic enzymes (Table 2).

We used multivariate logistic regression to determine whether WBC, AST, and ALT could serve to predict liver laceration. The WBC count and AST remained as significant multivariate predictors of liver laceration in our patients with blunt abdominal injuries (P = .002 and 0.010, respectively). The odds ratio for WBC count and AST in the prediction of

Table 2 Analysis of WBC and hepatic enzymes between grades

I (7)

II (12)

III (11)

IV (10)

V (2)

P

AST

264 +- 262

167 +- 158

355 +- 160

432 +- 211

914 +- 377

.002

ALT

199 +- 226

132 +- 133

296 +- 152

377 +- 241

372 +- 192

.144

WBC

10 913 +- 4483

15 375 +- 6161

12 946 +- 4211

12 366 +- 4447

28 670 +- 9744

.003

One-way analysis of variance was performed comparing grade of hepatic injury against AST, ALT, and WBC count.

Factor

B

Odds

P

95% CI

ratio

Lower

Upper

AST

0.007

1.007

.002

1.003

1.012

WBC

0.298

1.347

.010

1.072

1.692

liver laceration were 1.347 (95% confidence interval [CI], 1.072-1.692) and 1.007 (95% CI, 1.003-1.012) (Table 3).

Table 3 Logistic regression analysis of potential risk factors for liver laceration of blunt abdominal injury

The risk factors included in the logistic regression model were AST, ALT, and WBC count.

Because of the 3 parameters having significant difference between the control and case groups, we cut a value for these 3 variables after reviewing the lower AST and ALT level reported in the previous studies. In a prospective study by Karaduman et al [15] in 87 consecutive hemodynamically stable pediatric Multiple trauma patients, they found a sudden rise up to 110.5 U/L in AST and 63.5 U/L in ALT indicating an intraabdominal injury, and severe hepatic injury should be suspected with higher levels of AST and ALT. In the study by Karam et al [13], they suggested that cutoff values for hepatic enzymes beneath cannot rule out liver injury after blunt abdominal trauma in children. Among their 16 patients with liver injury, 10 (63%) had AST less than 450 IU/L and 7 (44%) had ALT less than 250 IU/L. Two patients had radiologic evidence of grade III liver injury with AST as low as 95 and 92 and ALT of 80 and 86, below all cutoff values recommended in the literature. They suggested that diagnosis of such lesions still relies on clinical and radiologic findings, as do other intraabdominal Organ injuries. Therefore, we used the cutoff value with serum levels of AST greater than 100 IU/L, ALT greater than 80 IU/L, and WBC count greater than 10 000/mm3 in combination. When these 3 parameters were used together, 90% sensitivity and 92.3% specificity in the liver laceration group were found.

Discussion

In the ED, patients sustaining blunt abdominal trauma with liver laceration may present with unstable hemody- namics and obvious hemoperitoneum. These patients do not bring diagnostic challenges because the strategy is clear. They generally receive prompt abdominal radiography studies that clearly illustrate the injuries after celiotomy for lesion repair or Damage controls in the operation room. However, in some circumstances, the liver lacerations were less significant or occult, making the decision to obtain abdominal CT difficult. In our study, we found that WBC counts and hepatic enzymes were significantly different in the 2 groups. The WBC counts can be a predictor of liver laceration. When combining these parameters, the sensitivity and specificity were high when cutoff values were set. These

serum biomarkers are available in almost every ED around the clock and compose basic laboratory workup in every patient with more significant trauma. Thus, an “early warning system” of possible existence of liver laceration can be easily set up.

In the case of blunt abdominal injury, the first clue surely lies in the hands of the physicians in the ED. Detailed physical examination could raise the suspicion of liver laceration when right upper quadrant abdominal pain or tenderness were complained about. Nevertheless, this finding is certainly equivocal. The pain is difficult to distinguish from that caused by blunt trauma of the local thoracic-abdominal wall. It was also unreliable when the patient was intoxicated, agitated, or compromised by various states. In trauma patients, a negative finding in physical examination cannot rule out any possible internal organ injury, and this is only meaningful when the finding is positive. However, even when there is a positive finding, it does not necessarily point to any specific injury. Another useful tool for initial survey is FAST, which is viewed as the “stethoscope” in trauma care [19]. It has long been widely accepted in detecting hemoperitoneum and also plays an important role in evaluating pregnant trauma patients. Unfortunately, FAST has limited value if the blunt abdominal trauma does not produce hemoperitoneum, and it may miss nearly one third of the abdominal injuries when used as the sole diagnostic tool in evaluating victims of blunt abdominal trauma [20]. Therefore, it would be a great help if the laboratory data could provide early warning for this potentially lethal injury.

Both AST and ALT have been previously reported to indicate hepatic injury [16,21]. One previous observational cohort study has reported serum ALT to be a sensitive diagnostic marker when evaluating harm caused by blunt hepatic injuries [22]. We found that AST is also sensitive to diagnose liver laceration because its levels rise higher than that of ALT. Although 4 (12.9%) and 6 (18.8%) of the patients with liver lacerations had AST and ALT levels less than 40 mg/dL in our study, all of them only had grades I and II injuries. Therefore, even in some patients whose enzyme levels are within normal levels and liver laceration cannot be completely ruled out, they can still provide some clues concerning liver injury, especially in patients with high-grade liver laceration. On the other hand, using combination of elevated WBC counts and liver enzymes as an indication of selecting patients for CT scans may bring some stable patients into this image study. These patients would otherwise possibly only be observed without further survey or even be discharged. Should liver laceration, even grade I or II, was found by CT scans, admission and even more aggressive study would surely be suggested. Also, this might alert the ED physicians for more detailed evaluation of possible coexisting injuries in these seemingly stable patients.

Leukocytosis is a very nonspecific indicator of inflamma- tion in general, dependent on individual variability and a

number of other factors. Theoretically, it would develop as demargination occurs as time passes after injury. If the laboratory draws were too early (or perhaps too late as well), this laboratory abnormality may not be present. However, in our study, the group with liver laceration had significantly different WBC counts from the control group (P = .001). In addition, different grades of liver laceration also had significantly different WBC counts (P = .003). We also found a trend that the more severe the laceration of the patients, the higher the WBC count, but the relationship was not conclusive. A similar relationship was found between grade and AST, though not with ALT.

Therefore, we proposed using a combination of the 3 parameters to detect the injury in the liver laceration patients. We set a cutoff value for each parameter and combined these to estimate the sensitivity and specificity after reviewing the lower AST and ALT value reported in the previous studies. When cutoff values of 10 000/mm3 for WBC counts, 100 IU/ L for AST, and 80 IU/L for ALT were set, we found there was 90% sensitivity and 92.3% specificity in our liver laceration group. Therefore, we established the evidence for common practice among pediatric surgeons and by some adult trauma surgeons in the diagnosis of liver laceration.

Limitations

Although this study is a retrospective study, there might be some limitations. Although liver enzymes have significant difference between liver laceration or without, they may be confounded by the presence of hepatitis or by the time that blood is drawn. However, we tried to exclude patients who had medical history of hepatitis and confined our patients to the group having their blood drawn within 6 hours to reduce the study bias. In fact, with this effort and the short transport time from trauma scene to ED in Taiwan (generally b 30 minutes), most of our patients had their first blood test within 60 minutes after injury. The patients’ WBC counts might also be influenced with the same problems. However, in our case group patients, they had not only liver laceration but also other Associated injuries after trauma as well, which may also influence WBC counts. Nevertheless, in both groups, WBC counts were higher than that of the normal population, and the case group was higher than the control one. Because most of our blunt abdominal patient injuries were caused by Motorcycle accidents, we attempted to eliminate confounders caused by other lesions, and most of our patients only had torso contusion without other major trauma.

In this study, we posed a question that was not able to be answered by our study design. We had hoped to analyze white blood cell count and serum hepatic enzymes to be used as an initial screening test to determine which blunt abdominal trauma patients not meeting standard criteria for abdominal CT scan would warrant getting a CT scan to detect liver injury. Unfortunately, this was not the group of patients

Fig. 1 Proposed algorithm for managing patients with occult hepatic injuries after blunt abdominal trauma.

that we eventually studied. Instead, we studied patients who met standard criteria for abdominal CT scan after blunt abdominal trauma. What we were able to demonstrate is that liver injuries severe enough to warrant a CT scan resulted in elevations of white blood cell count and serum hepatic enzymes. What we were not able to demonstrate with the study design is that these tests could be used as an initial screening to determine which patients not meeting standard criteria for CT scanning should still undergo a CT scan so as not to miss a liver injury. Thus, our study design also cannot prove whether there is any clinical significance to detecting minor liver injuries that may be picked up in a CT scan done on a patient not meeting standard criteria for CT scanning after blunt abdominal trauma. However, we attempted to find a useful tool to diagnose critical problems with high specificity in undetermined hemodynamically stable trauma patients before further examination. Although it is inevitable that sensitivity would decrease, the combination for diagnosis will exhibit higher specificity when applied to general trauma patients. In our study, it was a single- institution experience and so its sample size was relatively small; we henceforth propose an algorithm for prospective studies in patients with blunt abdominal trauma and having

occult hepatic injuries (Fig. 1). In this study, we did not rule out the liver laceration below the cutoff values, we suggested when to obtain abdominal CT for further evaluation. We hope in the future, based upon the data, that CT can be reduced in patients with normal clinical findings and normal liver enzymes.

Conclusion

In conclusion, this study suggests that, in patients sustaining blunt abdominal trauma, concomitant serum levels of AST greater than 100 IU/L, ALT greater than 80 IU/L, and WBC count greater than 10 000/mm3 strongly indicate liver laceration, and more active diagnostic strategy should be taken.

References

  1. Carrillo EH, Platz A, Miller FB, et al. Non-operative management of Blunt hepatic trauma. Br J Surg 1998;85:461-8.
  2. Richards JR, McGahan JP, Pali MJ, et al. Sonographic detection of blunt hepatic trauma: hemoperitoneum and parenchymal patterns of injury. J Trauma 1999;47:1092-7.
  3. Ferrera PC, Verdile VP, Bartfield JM, et al. Injuries distracting from Intraabdominal injuries after blunt trauma. Am J Emerg Med 1998;16: 145-9.
  4. Mackersie RC, Tiwary AD, Shackford SR, et al. intra-abdominal injury following blunt trauma. Identifying the high-risk patient using objective risk factors. Arch Surg 1989;124:809-13.
  5. Carrillo EH, Spain DA, Wohltmann CD, et al. Interventional techniques are useful adjuncts in Nonoperative management of hepatic injuries. J Trauma 1999;46:619-22 [discussion 22-4].
  6. Schurink GW, Bode PJ, van Luijt PA, et al. The value of physical examination in the diagnosis of patients with blunt abdominal trauma: a retrospective study. Injury 1997;28:261-5.
  7. Nural MS, Yardan T, Guven H, et al. Diagnostic value of ultrasonography in the evaluation of blunt abdominal trauma. Diagn Interv Radiol 2005;11:41-4.
  8. Brown MA, Casola G, Sirlin CB, et al. Blunt abdominal trauma: screening us in 2,693 patients. Radiology 2001;218:352-8.
  9. Sirlin CB, Brown MA, Andrade-Barreto OA, et al. Blunt abdominal trauma: clinical value of negative screening US scans. Radiology 2004;230:661-8.
  10. Kirkpatrick AW, Sirois M, Laupland KB, et al. Prospective evaluation of hand-held focused abdominal sonography for trauma (FAST) in blunt abdominal trauma. Can J Surg 2005;48:453-60.
  11. Miller MT, Pasquale MD, Bromberg WJ, et al. Not so FAST. J Trauma

2003;54:52-9 [discussion 9-60].

  1. Mendelow AD, Timothy J, Steers JW, et al. Management of patients with head injury. Lancet 2008;372:685-7.
  2. Karam O, La Scala G, Le Coultre C, et al. Liver function tests in children with blunt abdominal traumas. Eur J Pediatr Surg 2007;17: 313-6.
  3. Capraro AJ, Mooney D, Waltzman ML. The use of routine laboratory studies as Screening tools in pediatric abdominal trauma. Pediatr Emerg Care 2006;22:480-4.
  4. Karaduman D, Sarioglu-Buke A, Kilic I, et al. The role of elevated liver transaminase levels in children with blunt abdominal trauma. Injury 2003;34:249-52.
  5. Puranik SR, Hayes JS, Long J, et al. Liver enzymes as predictors of liver damage due to blunt abdominal trauma in children. South Med J 2002;95:203-6.
  6. Holmes JF, Sokolove PE, Land C, et al. Identification of intra- abdominal injuries in children hospitalized following blunt torso trauma. Acad Emerg Med 1999;6:799-806.
  7. Cogbill TH, Moore EE, Feliciano DV, et al. Hepatic enzyme response and hyperpyrexia after severe liver injury. Am Surg 1992; 58:395-9.
  8. Rozycki GS, Ballard RB, Feliciano DV, et al. Surgeon-performed ultrasound for the assessment of truncal injuries: lessons learned from 1540 patients. Ann Surg 1998;228:557-67.
  9. Chiu WC, Cushing BM, Rodriguez A, et al. Abdominal injuries without hemoperitoneum: a potential limitation of focused abdominal sonography for trauma (FAST). J Trauma 1997;42:617-23 [discussion 23-5].
  10. Stassen NA, Lukan JK, Carrillo EH, et al. Examination of the role of Abdominal computed tomography in the evaluation of victims of trauma with increased aspartate aminotransferase in the era of focused abdominal sonography for trauma. Surgery 2002;132:642-6 [discus- sion 6-7].
  11. Srivastava AR, Kumar S, Agarwal GG, et al. Blunt abdominal injury: serum ALT-A marker of liver injury and a guide to assessment of its severity. Injury 2007;38:1069-74.

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