Infected pancreatic necrosis

Diffusion-Weighted Magnetic Resonance Imaging Is an Ideal Imaging Method to Detect Infection in Pancreatic Collections: A Brief Primer for the Gastroenterologists

Background: The development of infection in pancreatitis significantly increases the mortality rate up to 100% in the absence of any intervention. Therefore, it is extremely important to diagnose these cases at an early stage. The objectives of this study were to assess the diagnostic performance of computed tomography (CT) and diffusion-weighted MR imaging (DW-MRI) in the diagnosis of infection in pancreatic collections.

Materials and methods: Prospective observational study of abdominal collections due to pancreatitis that underwent both CT and DW-MRI from August 2018 to July 2020 were enrolled in the study. The collections were analysed for infections - air foci in CT and diffusion restriction on DW-MRI.

Results: Of the 39 patients recruited in the study, infected collections were present in 17, and 22 cases had sterile collections. On CT, air foci within the collection were present only in seven of the cases in our study (sensitivity 35%, specificity 95.4%, PPV 85.7%, NPV 65.6%). DW-MRI detected infection in all 17 cases (sensitivity 100%, specificity 72.7%, PPV 74%, NPV 100%).

Discussion: Thirteen out of 17 collections suspicious for infection on DW-MR showed microbiological growth on culture examination. We believe that this is likely due to the patient's prior antibiotic use, which might have altered the micro-environment or inflammatory cell and bacterial content of the collection.

Conclusion: DW-MRI is complementary and superior to CT in detecting infection in pancreatic collections. CT may be used to detect disease burden, extent and vascular complication.

Serum C-reactive protein, procalcitonin, and lactate dehydrogenase for the diagnosis of pancreatic necrosis

BACKGROUND

The treatment of people with pancreatic necrosis differs from that of people with oedematous pancreatitis. It is important to know the diagnostic accuracy of serum C-reactive protein (CRP), serum procalcitonin, and serum lactate dehydrogenase (LDH) as a triage test for the detection of pancreatic necrosis in people with acute pancreatitis, so that an informed decision can be made as to whether the person with pancreatic necrosis needs further investigations such as computed tomography (CT) scan or magnetic resonance imaging (MRI) scan and treatment for pancreatic necrosis started. There is currently no standard clinical practice, although CRP, particularly an increasing trend of CRP, is often used as a triage test to determine whether the person requires further imaging. There is also currently no systematic review of the diagnostic test accuracy of CRP, procalcitonin, and LDH for the diagnosis of pancreatic necrosis in people with acute pancreatitis.

OBJECTIVES

To compare the diagnostic accuracy of CRP, procalcitonin, or LDH (index test), either alone or in combination, in the diagnosis of necrotising pancreatitis in people with acute pancreatitis and without organ failure.

SEARCH METHODS

We searched MEDLINE, Embase, Science Citation Index Expanded, National Institute for Health Research (NIHR HTA and DARE), and other databases until March 2017. We searched the references of the included studies to identify additional studies. We did not restrict studies based on language or publication status, or whether data were collected prospectively or retrospectively. We also performed a 'related search' and 'citing reference' search in MEDLINE and Embase.

SELECTION CRITERIA

We included all studies that evaluated the diagnostic test accuracy of CRP, procalcitonin, and LDH for the diagnosis of pancreatic necrosis in people with acute pancreatitis using the following reference standards, either alone or in combination: radiological features of pancreatic necrosis (contrast-enhanced CT or MRI), surgeon's judgement of pancreatic necrosis during surgery, or histological confirmation of pancreatic necrosis. Had we found case-control studies, we planned to exclude them because they are prone to bias; however, we did not locate any. Two review authors independently identified the relevant studies from the retrieved references.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data, including methodological quality assessment, from the included studies. As the included studies reported CRP, procalcitonin, and LDH on different days of admission and measured at different cut-off levels, it was not possible to perform a meta-analysis using the bivariate model as planned. We have reported the sensitivity, specificity, post-test probability of a positive and negative index test along with 95% confidence interval (CI) on each of the different days of admission and measured at different cut-off levels.

MAIN RESULTS

A total of three studies including 242 participants met the inclusion criteria for this review. One study reported the diagnostic performance of CRP for two threshold levels (> 200 mg/L and > 279 mg/L) without stating the day on which the CRP was measured. One study reported the diagnostic performance of procalcitonin on day 1 (1 day after admission) using a threshold level of 0.5 ng/mL. One study reported the diagnostic performance of CRP on day 3 (3 days after admission) using a threshold level of 140 mg/L and LDH on day 5 (5 days after admission) using a threshold level of 290 U/L. The sensitivities and specificities varied: the point estimate of the sensitivities ranged from 0.72 to 0.88, while the point estimate of the specificities ranged from 0.75 to 1.00 for the different index tests on different days of hospital admission. However, the confidence intervals were wide: confidence intervals of sensitivities ranged from 0.51 to 0.97, while those of specificities ranged from 0.18 to 1.00 for the different tests on different days of hospital admission. Overall, none of the tests assessed in this review were sufficiently accurate to suggest that they could be useful in clinical practice.

AUTHORS' CONCLUSIONS

The paucity of data and methodological deficiencies in the studies meant that it was not possible to arrive at any conclusions regarding the diagnostic test accuracy of the index test because of the uncertainty of the results. Further well-designed diagnostic test accuracy studies with prespecified index test thresholds of CRP, procalcitonin, LDH; appropriate follow-up (for at least two weeks to ensure that the person does not have pancreatic necrosis, as early scans may not indicate pancreatic necrosis); and clearly defined reference standards (of surgical or radiological confirmation of pancreatic necrosis) are important to reliably determine the diagnostic accuracy of CRP, procalcitonin, and LDH.

Antibiotic therapy for prophylaxis against infection of pancreatic necrosis in acute pancreatitis

BACKGROUND

Pancreatic necrosis may complicate severe acute pancreatitis, and is detectable by computed tomography (CT). If it becomes infected mortality increases, but the use of prophylactic antibiotics raises concerns about antibiotic resistance and fungal infection.

OBJECTIVES

To determine the efficacy and safety of prophylactic antibiotics in acute pancreatitis complicated by CT proven pancreatic necrosis.

SEARCH STRATEGY

Searches were updated in November 2008, in The Cochrane Library (Issue 2, 2008), MEDLINE, EMBASE, and CINAHL. Conference proceedings and references from found articles were also searched.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing antibiotics versus placebo in acute pancreatitis with CT proven necrosis.

DATA COLLECTION AND ANALYSIS

Primary outcomes were mortality and pancreatic infection rates. Secondary end-points included non pancreatic infection, all sites infection, operative rates, fungal infections, and antibiotic resistance. Subgroup analyses were performed for antibiotic regimen (beta-lactam, quinolone, and imipenem).

MAIN RESULTS

Seven evaluable studies randomised 404 patients. There was no statistically significant effect on reduction of mortality with therapy: 8.4% versus controls 14.4%, and infected pancreatic necrosis rates: 19.7% versus controls 24.4%. Non-pancreatic infection rates and the incidence of overall infections were not significantly reduced with antibiotics: 23.7% versus 36%; 37.5% versus 51.9% respectively. Operative treatment and fungal infections were not significantly different. Insufficient data were provided concerning antibiotic resistance.With beta-lactam antibiotic prophylaxis there was less mortality (9.4% treatment, 15% controls), and less infected pancreatic necrosis (16.8% treatment group, 24.2% controls) but this was not statistically significant. The incidence of non-pancreatic infections was non-significantly different (21% versus 32.5%), as was the incidence of overall infections (34.4% versus 52.8%), and operative treatment rates. No significant differences were seen with quinolone plus imidazole in any of the end points measured. Imipenem on its own showed no difference in the incidence of mortality, but there was a significant reduction in the rate of pancreatic infection (p=0.02; RR 0.34, 95% CI 0.13 to 0.84).

AUTHORS' CONCLUSIONS

No benefit of antibiotics in preventing infection of pancreatic necrosis or mortality was found, except for when imipenem (a beta-lactam) was considered on its own, where a significantly decrease in pancreatic infection was found. None of the studies included in this review were adequately powered. Further better designed studies are needed if the use of antibiotic prophylaxis is to be recommended.

What is the outcome for patients presenting with severe acute pancreatitis requiring a hospital stay of more than one month?

OBJECTIVE

The aim of this study was to investigate the clinical progression of patients who had severe acute pancreatitis (AP) and a stay in hospital of more than a month.

METHODS

A total of 24 patients (median age: 57 years) were included in this eight-year retrospective study. Cure was defined as the restoration of the pancreatic parenchyma, and the disappearance of all pseudocysts and pancreatic fistulae. Data including the duration of hospital stay, disease severity and pancreatic sequelae were also collected.

RESULTS

The median total duration of the hospital stay was 67 days. The overall mortality rate was 20.8%, whereas the mortality rate due to AP was 12.5%. The average healing period was 7.7 months. On univariate analysis, patients who also had respiratory diseases, chronic alcoholism, necrotizing superinfection, pseudocyst, food intolerance and/or hospital-acquired infection took significantly longer to heal. After cure, we observed pancreatic and/or hepatic duct stenoses in 50% of cases, and the onset or aggravation of diabetes in 25%.

CONCLUSION

In patients hospitalized for more than one month because of necrotizing AP, the rate of mortality is around 20%, with a final hospital stay of two months and a healing period of more than seven months. In addition, half of the patients presented with pancreatic or biliary sequelae.

Severe acute pancreatitis: Pathogenetic aspects and prognostic factors

Approximately 20% of patients with acute pancreatitis develop a severe disease associated with complications and high risk of mortality. The purpose of this study is to review pathogenesis and prognostic factors of severe acute pancreatitis (SAP). An extensive medline search was undertaken with focusing on pathogenesis, complications and prognostic evaluation of SAP. Cytokines and other inflammatory markers play a major role in the pathogenesis and course of SAP and can be used as prognostic markers in its early phase. Other markers such as simple prognostic scores have been found to be as effective as multifactorial scoring systems (MFSS) at 48 h with the advantage of simplicity, efficacy, low cost, accuracy and early prediction of SAP. Recently, several laboratory markers including hematocrit, blood urea nitrogen (BUN), creatinine, matrix metalloproteinase-9 (MMP-9) and serum amyloid A (SAA) have been used as early predictors of severity within the first 24 h. The last few years have witnessed a tremendous progress in understanding the pathogenesis and predicting the outcome of SAP. In this review we classified the prognostic markers into predictors of severity, pancreatic necrosis (PN), infected PN (IPN) and mortality.

Value of routine clinical tests in predicting the development of infected pancreatic necrosis in severe acute pancreatitis

OBJECTIVE

Fine-needle aspiration (FNA) is the procedure of choice for accurate diagnosis of infected necrosis. However, invasive procedures increase the risk of secondary pancreatic infection and the timing of FNA is still a matter for debate. Our objective was to assess the value of routine clinical tests to determine the minimal risk for infected necrosis, thereby optimizing timing and selection of patients for image-guided FNA.

MATERIAL AND METHODS

This prospective, non-randomized study comprised 90 patients with acute necrotizing pancreatitis. The data of 52 patients were used for discriminant function analysis to determine the differences between patients with infected necrosis and those with sterile necrosis. Cut-off points for variables were established using receiver operating characteristic (ROC) curve analysis and logistic regression was performed to determine the risk of infected necrosis. The clinical relevance of the defined diagnostic system was prospectively tested in a further 38 consecutive patients with acute necrotizing pancreatitis (ANP).

RESULTS

Discriminant function analysis showed that C-reactive protein (CRP) and white blood cell (WBC) values were significant discriminators between patients with sterile necrosis and those with infected necrosis. Cut-off values of 81 mg/l for CRP and 13 x 10(9)/l for WBC were established. The predicted risk for infected necrosis is approx. 1.4% if both tests are below the defined cut-off values. Consequently, we found FNA unnecessary in this subset of patients, unless otherwise indicated, as this invasive procedure per se carries a certain risk of bacterial contamination.

CONCLUSIONS

Routine clinical tests are helpful in diagnosing the development of infected necrosis. Based on the application of classification functions, the timing and selection of patients for image-guided FNA can be optimized.

Complications of acute pancreatitis: clinical and CT evaluation

Mortality of acute pancreatitis is dependent on the development of potentially lethal complications that can coexist and occur at any time following an acute attack. The nature and clinical relevance of these complications differ, contingent on the time of occurrence following a severe episode of pancreatitis. They can be divided into (1), early complications that manifest at the onset or within the first 2 to 3 days, (2) intermediate complications that occur predominantly during the second to fifth week, and (3) late complications that usually manifest months or years following the resolution of an acute attack. Early complications are systemic in nature with diverse clinical manifestations of the cardiovascular, pulmonary, renal, and/or metabolic systems. Intermediate complications are abdominal, pancreatic, and retroperitoneal, and are mostly septic in nature, associated with pancreatic or peripancreatic fat necrosis and pseudocysts. Late, life-threatening complications are mainly vascular or hemorrhagic in nature or involve the development of chronic pancreatic ascites. The early detection and objective evaluation of these complications by clinical and imaging methods leads to specific treatment options in the continuous attempt to decrease mortality rates in acute pancreatitis.

Diagnosis, objective assessment of severity, and management of acute pancreatitis. Santorini consensus conference

BACKGROUND

The diagnosis, early assessment, and management of severe acute pancreatitis remain difficult clinical problems. This article presents the consensus obtained at a meeting convened to consider the evidence in these areas. The aim of the article is to provide outcome statements to guide clinical practice, with an assessment of the supporting evidence for each statement.

METHOD

Working groups considered the published evidence in the areas of diagnosis, assessment of severity, nonoperative treatment, and surgical treatment of severe acute pancreatitis. Outcome statements were defined to summarize the conclusions on each point considered. The findings were discussed and agreed on by all participants. A careful assessment was made of the strength of the available evidence (proven, probable, possible, unproven, or inappropriate).

FINDINGS AND CONCLUSIONS

There is reliable evidence to support much current practice. Clear guidance can be given in most areas examined, and several areas were identified where further investigation would be helpful. Diagnosis using plasma concentrations of pancreatic enzymes is reliable. Rapid advances are taking place in the assessment of severity. Several new therapeutic strategies show real promise for the reduction of morbidity and mortality rates. Surgical debridement is required for infected pancreatic necrosis, but is less often necessary for sterile necrosis.