Fistula

Base HP	Stage HP
60	0

Ingame Appearance

Entity ID
71.0

Found In
Boss






Degraded Boss
Small



Medium



Large

Dropped Items
Boss

Fistula is a boss that can appear:

• in The Cellar.
• in The Caves and the Flooded Caves.

The large Fistula has 60 HP, the medium forms have 15 HP, and the small forms have 8 HP.

Behavior

• Moves around the room slowly, bouncing off the walls.
• When enough health is depleted, the one large Fistula breaks into four medium Fistulas.
  • Medium forms behave identically but move slightly faster.
• Each of the four medium Fistulas breaks into two small Fistulas.
  • Small forms behave identically but move very fast.
• Each of the smallest Fistulas spawns a Charger on defeat unless they are over a pit or other obstacle.
• All stages of Fistula will do 1 full heart of contact damage.

Champion Versions

• Dark Grey: 15% larger with 25% more HP (75). Spawns Boom Flies instead of Chargers. Each piece travels much slower and splits into three medium Fistulas as opposed to the original's four, similar to Teratoma.

Gallery

• 

  Fistula in-game.

• 

  Medium-sized Fistula.

• 

  Small Fistula.

• 

  Dark Grey Champion Fistula before Repentance.

• 

  Medium-sized Dark Grey Champion Fistula before Repentance.

• 

  Small Dark Grey Champion Fistula before Repentance.

• 

  Fistula as one of Delirium's forms.

Trivia

• Fistula appeared in the original The Binding of Isaac.
• A fistula is an abnormal connection between organs, intestines, and other tissues.
• Fistula’s splittings after taking enough damage is a reference to the game Asteroid, where asteroids would float diagonally and split after taking enough damage. This was confirmed by Edmund McMillen.
• Fistula used to be a Caves/Catacombs boss in the original The Binding of Isaac, but as of Rebirth, it is a Cellar boss.
  • It has been moved back into the Caves as of Repentance.
• Teratoma is the posthumous version of Fistula.
• Unlike the original The Binding of Isaac, Fistula doesn't bounce off of rocks.
• Fistula was inspired by a boss of the same name in another Edmund McMillen game, C-Word.
• Fistuloid is an enemy variant of this boss combined with what looks to be a Charger or Spitty.
• The Matriarch is a boss added in Booster Pack #5 that is simultaneously based of a Fistuloid, Chub, and this boss. The Matriarch will also spawn small Fistulas throughout the battle.
• Mother will spawn a unique Fistula during one of her attacks.
• Fistula is one of four bosses that can be spawned by It Lives, the other three being Chub, Polycephalus and Teratoma.