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April 2013, Volume 63, Issue 4

Original Article

Traumatic pancreatic injury - an elusive diagnosis: experience from a developing country urban trauma referral centre

Ayaz Ahmed Memon  ( Department of General Surgery, Aga Khan University Hospital, Karachi. )
Hasnain Zafar  ( Department of General Surgery, Aga Khan University Hospital, Karachi. )
Rushna Raza  ( Department of General Surgery, Aga Khan University Hospital, Karachi. )
Ghulam Murtaza  ( Department of General Surgery, Aga Khan University Hospital, Karachi. )

Abstract

Objective: To determine the frequency of pancreatic injury in patients presenting with trauma and to review the mechanism of injury, management, subsequent complications and in-hospital mortality rate associated with these patients.
Methods: The retrospective study included all patients over 18 years of age presenting with pancreatic injury due to trauma at the Aga Khan University Hospital, Karachi, between January 1990 and December 2009. Patients with iatrogenic pancreatic injury were excluded. The severity of the injury was assessed using the Injury Severity Score, while it was graded according to the scale defined by the American Association for the Surgery of Trauma. SPSS 17 was used for statistical analysis.
Results: A total of 30 patients were identified representing just 1.5% of the total adult abdominal trauma patients. The mean age of the patients was 28±9.7 years. There were 28 (93.3%) males and just 2 (6.6%) females. The complication rate was 80% (n=24) and the mortality rate was 23.3% (n=7). Of the 30 patients, 19 (63%) had been transferred from some other medical facility. The mean length of hospital stay was 16.4±20.6 days (range 5-97 days).
Conclusion: Surgical management in pancreatic trauma patients should be dictated by the degree and location of pancreatic injury, associated injuries and time from event to presentation. Mortality was primarily determined by associated life-threatening injuries.
Keywords: Pancreatic trauma, Pancreatic fistula, Pancreatic pseudocyst, Developing country. (JPMA 63: 440; 2013)

Introduction

Pancreatic injuries continue to challenge trauma surgeons. The relative rarity of these unforgiving injuries with an incidence of around 3-4% in patients with abdominal trauma,1 compounded with the difficulty of diagnosing them in a timely manner, and the high morbidity and mortality associated with them explain some of the anxiety they evoke.
The deep, central, and retroperitoneal location of the pancreas confers protection to this organ, but it also means that pancreatic injuries rarely occur alone and are often associated with other intra-abdominal injuries.2 Mortality of pancreatic trauma ranges from 9% to 46% and is related to the associated injuries, as much as to the pancreatic injury itself; hence wisdom dictates that the patients must be managed as all other trauma patients with the aim of ensuring haemodynamic stability first, before any specific treatment of the pancreatic injury is undertaken. Early recognition, adherence to the basic concepts of haemostasis of associated vascular injury, minimising bacterial contamination, accurate assessment of the pancreatic injury, judicious resection and adequate drainage can significantly diminish morbidity and mortality.3,4
The relative dearth of data on pancreatic trauma in international literature is compounded by a virtual absence of information about the epidemiology and outcomes of such injuries from the developing world. The likelihood of missed diagnoses, delayed intervention and, therefore, poorer outcomes seems higher in the face of limited resources, diagnostic capabilities and uneven inter-institutional referral that is prevalent in these setups. We, therefore, reviewed our own institutional experience as a major urban referral centre for complex multi-organ trauma from the last two decades.

Patients and Methods

The retrospective analytical study was conducted at the Aga Khan University Hospital, Karachi, and reviewed the medical records of all patients aged 18 years and older, who presented with pancreatic trauma over the last 20 years i.e. 1990-2009. The study was exempted from Ethical Review Committee approval as per institutional guidelines as it was a retrospective review of patient files. Patient consent that data can be used for any scientific study is taken as a routine at the institute. The data was retrieved from hospital records using International Classification of Diseases (ICD) code 863.81-84, 863.91-94. Patients with iatrogenic pancreatic injuries were excluded from the study. The variables collected included socio-demographic parameters, clinical indicators, laboratory and radiological investigations, hospital management and its outcomes. Total hospital stay, complications and in-hospital mortality were considered major outcomes. The severity of the injury was assessed using the Injury Severity Score (ISS) and the pancreatic injury was graded using the American Association for the Surgery of Trauma (AAST) pancreatic injury scale (Table-1).5


Data were analysed using SPSS 17.0. Continuous variables were analysed as means and standard deviations, whereas categorical variables were analysed as frequencies and percentages. Correlation of pancreatic injury with ISS was determined by Pearson correlation coefficient.

Results

Thirty patients were identified with objective radiological or operative evidence of pancreatic trauma during the study period. The mean age of these patients was 28±9.7 years with male predominance (n=28; 93.3%). Pancreatic injury was observed in 1.5% of the total patients presenting with trauma. Of the 30 patients, 19 (63%) had been transferred from some other medical facility, while 11 (36.6%) patients primarily presented to our emergency department.
Eleven (36.6%) patients had blunt trauma out of which 9 (30%) were involved in road traffic accidents, and 2 (6.6%) had fallen from a height. Besides, 19 (63%) patients received penetrating injuries, out of which 14 (46.6%) had gunshot injuries, 3 (10%) had stab wounds and 2 (6.66%) individuals sustained secondary bomb blast injuries.
The mean revised trauma score of the injured at the time of Emergency Room (ER) presentation was 7.43±0.4 (range 3.47-7.84). Eight (26.7%) patients presented with profound shock; 12 (40%) had vitals corresponding to mild shock; and 27 (90%) had signs of acute surgical abdomen.
The mean ISS at presentation was 24.7±11.7 (1–75) with 5 (16.67%) patients having a score of 75 (considered non-survivable). Only 2 (6.6%) patients had isolated pancreatic injury, whereas all other patients had associated injuries to bowel, solid organs or vascular structures. Altogether 46.7% patients presented within 1-2 hours of injury. Mean length of hospital stay was 16.4±20.6 days, and was higher in patients transferred from other hospitals.
On arrival at ER, serum amylase was done in 10 (33.3%) patients and was found raised in 7 (23.3%). Focussed abdominal sonography for trauma (FAST) was done in 9 (30%) patients and was positive in all. Computed tomography (CT) scan was done on 13 (43.3%) patients, and pancreatic trauma was diagnosed in 10 (76%) of them, while in the other 3 (10%), initial CT scans were inconclusive. Subsequent CT scans of 2 (6.6%) of these patients revealed pancreatic injury. Endoscopic retrograde cholangiopancreatography (ERCP) and magnetic resonance cholangiopancreatography (MRCP) were not done in any of the 30 patients.
Most of the patients had grade 3 or 4 injuries (n=16; 53.3%) out of which 14 (46.6%) underwent surgery. However, 27 (90%) patients required surgical intervention regardless of their pancreatic injury grade as the indication for surgery was primarily due to associated injuries. Pancreatic resection was done in 5 (16.6%) patients with injury to the distal part of pancreas, and drainage procedures were carried out in 18 (60%) patients with injuries of lesser severity. There was a moderate correlation between ISS and the grade of pancreatic injury (Pearson Correlation coefficient= 0.62; p-value <0.012) with higher ISS predicting higher grades.
Individual details of all patients presenting with blunt and penetrating pancreatic trauma were noted (Table-2, 3).


Isolated pancreatic injury was identified in 2 (6.6%) patients; one of them had a grade 2 injury secondary to blunt trauma. The patient had a delayed presentation after developing pseudocyst as a complication. The other victim had grade 1 pancreatic injury due to penetrating trauma. Both of these patients were managed conservatively.
Complications observed in this study included pancreatic fistula (n=5, 16.7%), paralytic ileus (n=4, 13.3%), pancreatic abscess (n=4, 13.3%), pseudocyst (n=5, 16.6%), and sepsis (n=2, 6.6%). All of them were witnessed in patients transferred from other facilities. Mortality rate was 23.3% (n=7), but none of the deaths were considered to be a direct consequence of pancreatic injury. Five (16.6%) deaths were due to exsanguinations, while sepsis and multi-organ failure secondary to other associated injuries was established as a cause of death in 2 (6.6%) patients.

Discussion

In our study, the frequency of pancreatic injury was 1.5% of total adult trauma patients per year with a complication rate of 80% and mortality of 23.3%.
Trauma is one of the leading causes of morbidity and mortality in under-developed and developed countries. Likewise, in Pakistan, trauma is a major reason for morbidity and mortality in early age groups. As with all previous pancreatic trauma series reporting incidence rate ranging from 0.21%-1%,4,6-8 this study also demonstrated the rarity of pancreatic injury in trauma patients.
The male predominance found in our study has also been reported in other studies from different regions of the world. Literature shows that males accounted for 88%, 76%, and 75% of the patients.8-10 This higher proportion may be explained by the higher percentage of males involved in trauma incidents.
Penetrating trauma was the leading cause of injury to pancreas in our study group. The mechanism of injury reported varies from region to region, depicting the type of trauma received. Studies from the United Kingdom have demonstrated blunt trauma as the mechanism of injury in around 82% of the patients with pancreatic injury.4,8 However, results from US and South Africa demonstrate penetrating trauma as the leading cause.11,12
As experienced by other trauma series, our study also validated the fact that victims belonged to young age group with a mean age of 28 years.
Isolated pancreatic injuries are uncommon.11,13 Such injuries, especially those which are low-grade in nature, maybe sub-clinical or present with delayed complications, can be managed conservatively with favourable outcomes, as also experienced in another series.13
Most patients in our study sustained grade 2-4 injury. However, a trauma series published from Scotland identified grade 2 injuries as the major burden of injury (i.e. 84% in their experience). Other published series showed that grade 1-3 pancreatic injuries were predominantly present.3,6 Our institute is a major tertiary care centre receiving referrals from surrounding hospitals. The higher injury grade in this study might be related to a greater proportion of transferred patients, as they also had greater severity or complexity of injury. This fact is also established in other studies which showed that the transferred group had grade 3-4 injuries as compared to the victims presenting primarily to the trauma centre.4 More than 90% of the patients in our study had associated injuries to other abdominal organs; most commonly hepatic, splenic and gastric injuries. Due to the unique anatomical position of the pancreas, the incidence of associated injuries has been reported to range between 73-100% of patients who have sustained pancreatic trauma.7,10,14,15
Interestingly, we identified combined pancreaticoduodenal injury in 16.7% of cases; all were the result of penetrating trauma. A study reported simultaneous duodenal injuries in 6% of its patients,8 while in cases of penetrating trauma the incidence of pancreaticoduodenal injury was between 12-21%.14,15
Although the highest concentration of amylase in the human body is in the pancreas, hyper-amylasaemia is not a reliable indicator of pancreatic trauma. In addition, there is evidence that isolated brain injury can cause elevated amylase levels through a central mechanism that remains to be clarified.16 Nonetheless, the presence of hyper-amylasaemia should raise the index of suspicion for pancreatic injury. In a report of 73 patients with documented blunt injury to the pancreas, serum amylase levels were elevated in 61 (84%) patients and normal in 12 (16%).17 Similar results were also experienced in this study. CT scan was done on 13 patients and pancreatic trauma was diagnosed in 10 (76%) of them. Although the sensitivity of CT scan in this study is higher compared to other series i.e. 45.4%,18 but in the other 3, initial CT scans were inconclusive. Subsequent, CT scans of 2 of these patients revealed pancreatic injury.
We did damage control surgery in 4 patients because they were hypovolaemic shock secondary to associated severe intra-abdominal vascular and other organ injuries. All of them died and their early mortality was the result of haemorrhagic shock with concomitant injuries. Other series have also commented on this finding.12,19-21
Complications were seen in 80% of our cases. Pancreatic fistula, abscess and pseudocyst predominated, and these were mostly seen in patients who were transferred from other hospitals with severe pancreatic injuries. These findings may indicate delay in treatment of more than 24 hours. Published series have reported complication rates between 12-62% and with a higher rate of complications in patients with delayed treatment.22-25
We failed to find any correlation between either the grade of pancreatic injury or the ISS with the length of hospital stay. This is probably reflective of the fact that the most grievously injured patients died shortly after presentation, while most moderately injured ones had a prolonged and complicated hospital stay with the minimally injured having an intermediate length of hospital stay.
Mortality after pancreatic trauma ranges from 9%-46%7and is usually the result of haemorrhagic shock and sepsis. It is rare for isolated pancreatic trauma to directly result in death. In this study, mortality was either a result of haemodynamic shock or multi-organ failure secondary to sepsis. Mortality rate in this study was 23.3%; however, severity of injury to pancreas does not reflect higher mortality.4,7,8,11

Conclusion

Pancreatic trauma is a rare entity and rarely found in isolation. Delayed presentation and diagnosis leads to increased morbidity. Initial CT scan might be inconclusive, so the injury must be presumed by the mechanism of injury. Surgical management in such patients should be dictated by the degree and location of pancreatic injury, associated injuries and time from event to presentation. The demographics, management and outcomes of pancreatic trauma from a limited-volume urban trauma referral centre in Pakistan compared favourably with literature from the West.

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