classification of acute pancreatitis...1942 –lagerlof classified pancreatitis as acute and chronic...

Classification

of Acute Pancreatitis

Andrzej Dąbrowski

Department of Gastroenterology

and Internal Medicine

Medical University of Bialystok, Poland

Why do we need good AP classification?

To improve clinical assessment of the AP

To facilitate communication between treating physicians

(uniformity)

For better reporting of clinical studies (common platform for

research)

Introduction – historical view

Pannala R et al. Pancreas 2009, 38, 355

Nicholaes Tulp (1593-1674) of

Amsterdam is credited with the

first description (1652) of acute

pancreatitis.


Pannala R et al. Pancreas 2009, 38, 355

Reginald Fitz in 1889 described

3 forms of acute pancreatitis

(hemorrhagic, suppurative, and

gangrenous) and proposed that

fat necrosis was a sequel of

severe pancreatitis


Frey CF, Pancreas 1986, 1, 62

1942 – Lagerlof classified pancreatitis as acute and chronic

based on clinical, functional, and pathologic observations from

autopsy and operative findings.

Beginning in 1955, Joske, then Janowitz in 1957, Howard in

1960, and Dreiling in 1964 developed a comprehensive

classification system of pancreatitis based on etiologic factors.

Blumenthal and Probstein in 1959 provided a classification

system based on etiology in which they then categorized 163

patients from clinical and autopsy criteria.

1963 - Marseille Classification of pancreatitis

I. Acute pancreatitis

II. Recurretnt acute pancreatitis

III. Recurrent chronic pancreatitis

IV. Chronic pancreatitis

1983 – Cambridge classification

1984 – the second Marseille symposium


Frey CF, Pancreas 1986, 1, 62

1983 – Cambridge classification

The Cambridge group defined the severity and complications of

acute pancreatitis.

An attack of acute pancreatitis was defined as “mild” if there was

no multisystem failure and “severe” if multisystem failure

occurred and/or there were early or late, local or systemic

complications.

The complications identified for definition were (a) phlegmon, an

inflammatory mass in and around the pancreas; (b) pseudocyst,

a localized collection of fluid containing high concentrations of

pancreatic enzymes within, adjacent to, or remote from the

pancreas: and (c) abscess, pus in or around the pancreas.

Atlanta classification (1992)

Bradley EL III, Arch Surg 1993, 128, 586

Definition

Acute

pancreatitis

(AP)

An acute inflammatory process of the pancreas with variable

involvement of other regional tissues or remote organ systems

Associated with raised pancreatic enzyme levels in blood

and/or urine

Severity

Mild AP Associated with minimal organ dysfunction and an uneventful

recovery; lacks the features of severe acute pancreatitis.

Usually normal enhancement of pancreatic parenchyma on

contrast-enhanced computed tomography

Severe AP Associated with organ failure and/or local complications such

as necrosis, abscess or pseudocyst

Predicted

severity

Ranson score ≥3 or APACHE II score ≥8



Definition

Organ failure and

systemic

complications

Shock Systolic blood pressure < 90 mmHg

Pulmonary

insufficiency

Pa O2≤60 mmHg

Renal failure Creatinine ≥177 µmol/l or ≤2 mg/dl after rehydration

Gastrointestinal

bleeding

500 ml in 24 h

Disseminated

intravascular

coagulation

Platelets ≤100, 000/mm3, fibrinogen < 1·0 g/l and fibrin-

split products > 80 µg/l

Severe metabolic

disturbances

Calcium ≤1·87 mmol/l or ≤7·5 mg/dl



Definition

Local

complications

Acute fluid

collections

Occur early in the course of acute pancreatitis, are located in

or near the pancreas and always lack a wall of granulation of

fibrous tissue. In about half of patients, spontaneous

regression occurs. In the other half, an acute fluid collection

develops into a pancreatic abscess or pseudocyst

Pancreatic

necrosis

Diffuse or focal area(s) of non-viable pancreatic parenchyma,

typically associated with peripancreatic fat necrosis

Non-enhanced pancreatic parenchyma > 3 cm or involving

more than 30% of the area of the pancreas



Definition

Local

complications

Acute

pseudocyst

Collection of pancreatic juice enclosed by a wall of fibrous or

granulation tissue, which arises as a result of acute pancreatitis,

pancreatic trauma or chronic pancreatitis, occurring at least 4

weeks after onset of symptoms, is round or ovoid and most

often sterile; when pus is present, lesion is termed a pancreatic

abscess

Pancreatic

abscess

Circumscribed, intra-abdominal collection of pus, usually in

proximity to the pancreas, containing little or no pancreatic

necrosis, which arises as a consequence of acute pancreatitis or

pancreatic trauma

Often 4 weeks or more after onset

Pancreatic abscess and infected pancreatic necrosis differ in

clinical expression and extent of associated necrosis

Definitions for organ failure and predicted

severe AP in guidelines published after 1993

Guideline Definitions for

organ failure

Definitions for severe AP

UK 2005 Refers to Atlanta

Classification

1992

At admission

Clinical assessment

BMI > 30 kg/m2

Pleural effusion

APACHE score > 8

At 24-48 h

Clinical assessment

Glasgow score ≥3

APACHE II score > 8

Persistent organ failure for 48 h (especially if

multiple and progressive)

CRP > 150 mg/l

Note: Organ failure present within 1 week, which resolves

within 48 h, should not be considered an indicator of a

severe attack of acute pancreatitisBollen TL et al., Br J Surg 2008, 95, 6

Definitions for organ failure and predicted

severe AP in guidelines published after 1993

Guideline Definitions for

organ failure

Definitions for severe AP

ACG 2006 Refers to Atlanta

Classification

1992

Note: Criteria of

organ failure will

change in the

future:

gastrointestinal

bleeding will

undoubtedly be

deleted

At admission

Age > 55 years

BMI > 30 kg/m2

Presence of organ failure

Pleural effusion/infiltrates

At 24-48 h

APACHE II score ≥ 8

Serum hematocrit ≥ 44%

Note: Ranson signs are no longer advocated, due to a

comprehensive evaluation of 110 studies that

concluded that Ranson signs provided very poor

predictive power of severity of acute pancreatitis

Bollen TL et al., Br J Surg 2008, 95, 6

Definitions of severe AP local complications

need revision

Bollen TL et al., Br J Surg 2008, 95, 6

Contrast-enhanced computed

tomography (CT) of a patient with

acute pancreatitis 30 days after onset

of symptoms. The fluid collection

seems to be homogeneous and

encapsulated (white arrows) and

could be interpreted as a pseudocyst

according to the Atlanta

Classification.

However, at operation the collection

was found to contain large amounts

of necrotic debris that CT had not

shown.

Acute

pseudocyst

(Atlanta 1992)

Collection of pancreatic juice enclosed by a wall of fibrous or granulation tissue,

which arises as a result of acute pancreatitis, pancreatic trauma or chronic

pancreatitis, occurring at least 4 weeks after onset of symptoms, is round or ovoid

and most often sterile; when pus is present, lesion is termed a pancreatic abscess

CT findings in AP

Besselink MGH et al, Pancreas 2006, 33, 331

The interobserver agreement of the Atlanta classification for categorizing

peripancreatic collections in acute pancreatitis on CT is poor. The Atlanta

classification should not be used to describe complications of acute

pancreatitis on CT.

CT findings in AP

Besselink MGH et al, Pancreas 2006, 33, 331

The use of the Atlanta classification on CT in

necrotizing pancreatitis. A, Computed

tomography scan 12 days after onset of disease.

The definitions chosen for this collection were

"pseudocyst" (n = 1), "pancreatic abscess" (n =

1), "pancreatic necrosis" (n = 1), and "mixture" (n

= 2). B, Computed tomography scan 27 days

after onset of disease. The definitions chosen for

this collection were "pancreatic abscess" (n = 3)

and "mixture" (n = 2). C, Computed tomography

scan 31 days after onset of disease. The

definitions chosen were "pancreatic necrosis" (n

= 1), "pancreatic abscess" (n = 1), "pseudocyst"

(n = 1), and "mixture" (n = 2).

Need for the revision

Although the Atlanta Classification has proved useful over the

following 16 years, many of the definitions proved confusing (used

inconsistently) and have not been accepted or utilized by the

pancreatic community (pancreatic gastroenterologists, surgeons, and

radiologists).

Revision of the Atlanta classification of AP

Acute Pancreatitis Classification Working Group. Revision of the Atlanta classification of acute pancreatitis

(3rd revision) . www. pancreasclub.com/resources/AtlantaClassification.pdf

DEFINITION OF ACUTE PANCREATITIS

The clinical definition of AP, whether in the presence or absence of

underlying chronic pancreatitis, requires two of the following three features:

1) abdominal pain suggestive strongly of AP,

2) serum amylase and/or lipase activity at least 3 times greater than the

upper limit of normal, and

3) characteristic findings of acute pancreatitis on transabdominal

ultrasonography or on CECT, which is considered to be the best, most

universally available imaging modality.




CLINICAL CLASSIFICATION (1st week)

DEFINITION OF SEVERITY OF ACUTE PANCREATITIS

The definition of the severity of acute pancreatitis (during the first week) is

based on clinical rather than morphologic parameters (thereafter; over the

first week) .

Initially at presentation and over the first 48 hours, patients should be

classified temporarily as having severe acute pancreatitis based on the

presence of the persistent systemic inflammatory response syndrome (SIRS)

and/or developing organ failure.

Several potential risk factors of severity and measurements related to the

acute pancreatitis that may reflect severity should be recorded ideally and

evaluated prospectively, including age, BMI, hematocrit, APACHE II scores,

and serum levels of C-reactive protein.

It should be stressed that serum amylase and lipase activities, while

important in the diagnosis of “acute pancreatitis,” are not of any

clinical importance in defining the severity of acute pancreatitis.




OVER THE FIRST WEEK

Over the first week, the distinction between non-severe old term: mild and

severe acute pancreatitis depends ultimately on the development of organ

failure.

Non-severe acute pancreatitis is defined as the absence of organ failure or

the presence of organ failure that does not exceed 48 hours in duration.

The definition of severe acute pancreatitis is the persistence of organ

failure that exceeds 48 hours duration (i.e., organ failure recorded at least

once during each of three consecutive days).

OF>48 hrs Severe AP




DEFINITION OF ORGAN FAILURE

Three organ systems should be assessed to define organ failure:

respiratory, cardiovascular, and renal.

Organ failure is best and most easily defined in accordance with the

Marshall scoring system as a score ≥2 for at least one of these three organ

systems: respiratory (pO2/FIO2); renal (serum creatinine in μmol/l or mg/dl);

and cardiovascular (systolic blood pressure in mm Hg).

Multi-system organ failure is defined as two or more organs failing over the

same 2- to 3-day period.


Acute Pancreatitis Classification Working Group. Revision of the

Atlanta classification of acute pancreatitis (3rd revision) . www.

pancreasclub.com/resources/AtlantaClassification.pdf

Marshall Scoring System

FIO2 = fraction of inspired oxygen




MORPHOLOGIC IMAGING-BASED CLASSIFICATION (used AFTER the first

week)

This new classification proposes the use of morphologic CECT criteria to

diagnose the specific type of acute pancreatitis:

• Acute interstitial edematous pancreatitis (IEP)

• Acute necrotizing pancreatitis.

A. Presence/absence and site(s) of necrosis, 3 subtypes:

• normal pancreatic parenchyma enhancement with peripancreatic

fluid collections (fat necrosis)

• one or more focal areas of nonenhancing pancreatic parenchyma

with peripancreatic fluid collections

• without peripancreatic fluid collections

B. Evidence for the presence/absence of infection (FNA, gas within

nonenhancing retroperitoneal tissue)




NECROTIZING PANCREATITIS

Pancreatic Parenchyma:

About 80% of patients with necrotizing pancreatitis have a variable extent

of pancreatic parenchymal necrosis on CECT.

The extent of necrosis is quantified in three categories: <30%, 30-50%,

and >50% of the total pancreatic parenchyma.

The presence of pancreatic parenchymal non-enhancement differentiates

necrotizing pancreatitis from IEP.

gland enlargement on CECT

minimal

diffuse

localized





Peripancreatic Tissues:

The presence or absence of necrosis in the peripancreatic tissues is more

difficult to evaluate by CECT, especially early in the course of the disease.

While the presence or absence of necrosis in the peripancreatic tissues is

not always possible to diagnose definitively with CECT, CECT may

suggest the presence of peripancreatic necrosis by the presence of

“thickening” of the paracolic gutters and of the base of the small bowel

mesentery, fat stranding and involvement of the anterior pararenal

spaces, or especially the presence of non-homogeneous fluid collections

containing solid components in one or more areas.



Characteristics of Necrosis:

The relative amount of liquid vs semi-solid components within areas of

necrosis varies with the time since onset of necrotizing pancreatitis.

As time evolves, the initially solid necrosis liquefies by a process of

liquefaction necrosis. Complete resolution of necrosis (weeks to months

later) may occur through liquefaction necrosis and eventual reabsorption

of the liquefaction. In some patients, complete reabsorption may never

occur.

If resorption does not take place, the area of liquefaction necrosis may

persist as an area of walled-off pancreatic necrosis (WOPN; organized

necrosis, necroma, or pancreatic sequestration) without symptoms or

may cause pain or mechanical obstruction of the duodenum and/or bile

duct.

solid

necrosis <1 week

semi-solid

necrosis

(PNPFC)>4 weeks

liquefied necrosis

(WOPN)

liquefaction liquefaction

(no resorption)





Infection:

Depending on the stage of the necrosis (primarily solid, semi-solid, or

liquefaction) and the organism(s) involved, the infected necrosis will have

varying amounts of suppuration (pus).

In the later stages of infected necrosis, the content may be predominantly

pus (in addition to some solid components) as the process of liquefaction

necrosis matures.

“Pancreatic abscess” according to the Atlanta Classification in 1992 is a

“localized collection of purulent material without significant necrotic

material;” most agree that the latter Atlanta definition of “pancreatic

abscess” is an exceedingly uncommon finding in necrotizing pancreatitis.

The current imaging-based classification does not use the term

“pancreatic abscess” in order to avoid this confusion.




Both acute IEP and necrotizing pancreatitis can be associated with

PANCREATIC AND PERIPANCREATIC FLUID COLLECTIONS




ACUTE PERIPANCREATIC FLUID COLLECTIONS (APFCs) (1st 4 weeks

after onset of IEP)

a. Sterile

b. Infected

These fluid collections arise in patients with IEP, have no solid

components, and result from parenchymal and/or peripancreatic

inflammation in the absence of necrosis. Resolve spontaneously within 6

weeks 40%, 80% if <6 cm; communication with pancreatic duct seen in

70%.

They exist predominantly adjacent to the pancreas, have no definable

wall, and are confined by the normal peripancreatic fascial planes,

primarily the anterior pararenal fascia.

APFCs arise presumably from rupture of the main duct or a small

peripheral pancreatic ductal side branch or they result from local edema

related to the pancreatic inflammation and have no connection with the

ductal system.

Old term: acute fluid collections




POST-NECROTIC PANCREATIC/PERIPANCREATIC FLUID COLLECTIONS

a. Sterile

b. Infected

Fluid collections arising in patients with acute necrotizing pancreatitis are

termed PNPFCs to distinguish them from APFCs and pseudocysts.

PNPFCs contain both fluid and necrotic contents to varying

degrees.

In PNPFCs, a continuum exists from the initial solid necrosis to

liquefaction necrosis, depending on duration of the disease since onset.

PNPFC may or may not have a connection with the pancreatic ductal

system.

NecrosisPNPFC

(necrosis+fluid)WOPN (infected or sterile)

late stage

Old term: acute fluid collections




PANCREATIC PSEUDOCYST

Non-infected

Pseudocysts on CECT become defined >4 weeks after onset of

pancreatitis as a well-circumscribed (clearly evident wall; capsule),

usually round or oval, homogeneous fluid collection surrounded by a well-

defined wall with no solid necrotic debris within the fluid collection.

Pseudocysts develop from an APFC that persists for >4 weeks after onset

of pancreatitis. Prior to 4 weeks, these collections are categorized as

APFC.

Old term: pancreatic pseudocyst




PANCREATIC PSEUDOCYST

Infected (suppurative)

Determination of presence or absence of infection in a pancreatic

pseudocyst is also potentially important.

An infected pancreatic pseudocyst contains purulent liquid without an

associated solid component (necrosis).

This definition differentiates pseudocyst from infected PNPFC and

infected WOPN. As with all peripancreatic fluid collections, image-guided

FNA with Gram stain and culture or the presence of extraluminal gas are

necessary to confirm the pre-interventional diagnosis of infection.

Old term: pancreatic abscess

http://www.laurentbrouat.com/wp-content/uploads/2009/10/boring-class.jpg

Acute pancreatitis has been described for the first time by:

A.Reginald Fitz

B.David Dreiling

C.Nicholaes Tulp

D.Hippokrates of Kos

What is the uncommon complication of acute pancreatitis:

A.Respiratory

B.Renal

C.Cardiovascular

D.Gastrointestinal bleeding

The true statement about acute peripancreatic fluid collections is:

A.Fluid collections arising in patients with acute necrotizing pancreatitis, but not in

patients with acute interstitial edematous pancreatitis.

B.Have no solid components, and result from parenchymal and/or peripancreatic

inflammation in the absence of necrosis.

C.Become defined >4 weeks after onset of pancreatitis as a well-circumscribed, usually

round or oval, homogeneous fluid collection surrounded by a well-defined wall with no

solid necrotic debris within the fluid collection.

D.Contain both fluid and necrotic contents to varying degrees.

classification of acute pancreatitis...1942 –lagerlof classified pancreatitis as acute and chronic...

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