Forrest classification: the six endoscopic classes (Forrest 1974)

The Forrest classification describes what a bleeding peptic ulcer looks like at endoscopy. Class I means active bleeding, class II means signs of a recent bleed and class III means a clean ulcer base. This calculator takes the class the endoscopist has assigned and returns it in a standard form with the calculator's description of that class.

Not a medical device. Not a diagnosis or dosing recommendation.

Use this calculator via API

GI calculators
Forrest JA et al. · 1974
Worked examples
Frequently asked questions

What is the Forrest classification?

It's a shared vocabulary for ulcer appearance. Rather than a points score, it's a set of named classes, each tied to something the endoscopist can see. Magent doesn't look at endoscopy images. You give it a class, and it normalises the label (for example IIa becomes iia) and returns the matching description.

The Forrest classes

Ia   active spurting
Ib   active oozing
IIa  non-bleeding visible vessel
IIb  adherent clot
IIc  flat pigmented haematin / coffee-ground base
III  clean ulcer base

Exact expression the calculator uses:

forrest in {ia, ib, iia, iib, iic, iii} as assigned by the caller (Forrest 1974); Ia active spurting, Ib active oozing, IIa non-bleeding visible vessel, IIb adherent clot, IIc flat pigmented haematin / coffee-ground base, III clean ulcer base

Input

Input	Meaning	Values
`forrest`	The class assigned at endoscopy	ia, ib, iia, iib, iic, iii (any capitalisation)

How the classification works

Class	Calculator's description
`ia`	Active spurting hemorrhage
`ib`	Active oozing hemorrhage
`iia`	Non-bleeding visible vessel
`iib`	Adherent clot
`iic`	Flat pigmented haematin / coffee-ground base
`iii`	Clean ulcer base / no signs of recent hemorrhage

Normalise the label to lower case.
Look up the description for that class.
Mark the matching class in the criteria list. Exactly one is marked.

Worked examples

These use Magent's own expected values for the calculator.

Example 1: class Ia

Input ia.
Description: Active spurting hemorrhage.

Example 2: class IIa

Input iia.
Description: Non-bleeding visible vessel.

Example 3: class III

Input iii.
Description: Clean ulcer base / no signs of recent hemorrhage.

History of the Forrest classification

Forrest and colleagues described endoscopic findings in bleeding in "Endoscopy in gastrointestinal bleeding", published in the Lancet in 1974. The classes carry Forrest's name.

When it's used

When an endoscopist records the appearance of a peptic ulcer in someone with upper gastrointestinal bleeding.

Where it's used

Endoscopy units, endoscopy reports and research on ulcer bleeding.

Who uses it

Gastroenterologists, endoscopists and surgeons. The calculator standardises the label and wording.

Limits of the calculation

The class depends entirely on what the endoscopist saw. The calculator can't check it.
Two observers can assign different classes to the same ulcer.
The calculator returns no rebleeding rates and gives no advice about endoscopic or other steps.
This page doesn't say what a class means for a particular person.

Clinical decisions belong to a qualified clinician who knows the patient.

Glasgow-Blatchford score uses blood tests and bedside findings before endoscopy.
Pre-endoscopy Rockall score uses age, shock and comorbidity before endoscopy.

Glossary

Endoscopy: looking inside the gut with a camera on a flexible tube.
Visible vessel: a raised blood vessel in the ulcer base.
Adherent clot: a clot stuck to the ulcer that doesn't wash away.
Haematin: dark, altered blood pigment.

Common mistakes

Treating it as a score. The classes are labels, not points.
Reading II as worse than I. Class I is active bleeding; class II is signs of a recent bleed.
Expecting rebleeding figures. The calculator doesn't return any.

Source

Forrest JA, et al. Endoscopy in gastrointestinal bleeding. Lancet. 1974;2(7877):394-397. DOI: 10.1016/s0140-6736(74)91770-x. PMID: 4136718

Frequently asked questions

What are the Forrest classes?

Ia active spurting, Ib active oozing, IIa non-bleeding visible vessel, IIb adherent clot, IIc flat pigmented haematin or coffee-ground base and III clean ulcer base.

Does the calculator give rebleeding rates?

No. It returns the class and its description, nothing else.

Does it matter whether I type IIa or iia?

No. The label is case-insensitive and is returned in lower case.

Does the calculator look at endoscopy images?

No. The class is assigned by the person entering it.