Gastrointestinal and Hepatobiliary · Pancreas · Original CTSI 1990; Modified CTSI 2004

Balthazar CT Severity Index and Modified CT Severity Index

Side-by-side comparison of the original Balthazar CT Severity Index and Modified CT Severity Index for grading the morphological severity of acute pancreatitis.

Purpose

To quantify the CT severity of acute pancreatitis using pancreatic and peripancreatic inflammatory changes, the extent of pancreatic necrosis and, in the modified index, extrapancreatic complications.

Component	Original Balthazar CTSI	Modified CTSI
Pancreatic inflammation	Grade A: normal pancreas = 0; Grade B: focal or diffuse enlargement = 1; Grade C: pancreatic abnormality with peripancreatic inflammation = 2; Grade D: single peripancreatic fluid collection = 3; Grade E: two or more fluid collections or gas in or adjacent to the pancreas = 4	Normal pancreas = 0; intrinsic pancreatic abnormality with or without peripancreatic inflammation = 2; pancreatic or peripancreatic fluid collection or peripancreatic fat necrosis = 4
Pancreatic necrosis	None = 0; up to 30% = 2; more than 30% to 50% = 4; more than 50% = 6	None = 0; up to 30% = 2; more than 30% = 4
Extrapancreatic complications	Not separately scored	One or more qualifying complications = 2 points in total: pleural effusion, ascites, vascular complication, extrapancreatic parenchymal complication or gastrointestinal tract involvement
Score calculation	Balthazar inflammatory grade points + pancreatic necrosis points; maximum score = 10	Pancreatic inflammation points + pancreatic necrosis points + extrapancreatic complication points; maximum score = 10
Severity category	Mild = 0–3; moderate = 4–6; severe = 7–10	Mild = 0–2; moderate = 4–6; severe = 8–10

How to use it

The original CTSI combines the Balthazar inflammatory grade, scored from 0 to 4, with the extent of pancreatic necrosis, scored from 0 to 6.
The modified CTSI simplifies both inflammation and necrosis scoring and adds 2 points for the presence of one or more extrapancreatic complications.
Both indices range from 0 to 10, but their severity bands are different because the modified CTSI produces only even-numbered totals.
These are morphological CT scores and are not equivalent to Revised Atlanta clinical severity, which is determined principally by organ failure and its duration.
Use Revised Atlanta terminology when describing pancreatic and peripancreatic collections, even when calculating an older CT severity index.

Common mistake

Do not confuse the Balthazar grade with the complete original CTSI: the CTSI requires addition of the pancreatic necrosis score. In the modified CTSI, extrapancreatic complications contribute 2 points in total, not 2 points for each complication.

Exam pearl

Original CTSI = inflammation 0–4 plus necrosis 0–6; modified CTSI = inflammation 0–4 plus necrosis 0–4 plus extrapancreatic complications 0 or 2.

Viva questions

What are the components of the original Balthazar CT Severity Index?: It is the sum of the Balthazar pancreatic and peripancreatic inflammatory grade, scored from 0 to 4, and the extent of pancreatic necrosis, scored from 0 to 6.
How are Balthazar grades A to E scored?: Grades A, B, C, D and E receive 0, 1, 2, 3 and 4 points respectively, progressing from a normal pancreas to multiple collections or gas in or adjacent to the pancreas.
How is pancreatic necrosis scored in the original CTSI?: No necrosis scores 0, up to 30% scores 2, more than 30% to 50% scores 4, and more than 50% scores 6.
How does the Modified CTSI differ from the original CTSI?: It simplifies pancreatic inflammation to 0, 2 or 4 points, simplifies necrosis to 0, 2 or 4 points, and adds 2 points for one or more extrapancreatic complications.
Which extrapancreatic complications are included in the Modified CTSI?: They include pleural effusion, ascites, vascular complications, extrapancreatic parenchymal complications and gastrointestinal tract involvement.
How are the original CTSI and Modified CTSI severity categories defined?: Original CTSI scores of 0–3, 4–6 and 7–10 indicate mild, moderate and severe disease. Modified CTSI scores of 0–2, 4–6 and 8–10 indicate mild, moderate and severe disease.
Is CT severity according to the Modified CTSI equivalent to Revised Atlanta clinical severity?: No. Modified CTSI is a morphological imaging score, whereas Revised Atlanta severity is based primarily on organ failure and whether it is transient or persists for more than 48 hours.
What is a common scoring error with extrapancreatic complications in the Modified CTSI?: Their presence adds only 2 points in total, irrespective of how many qualifying extrapancreatic complications are present.