However, there are a few possibilities for what you might be referring to:

At first glance, the viewer sees what looks like a bowl of soup inside the patient’s anatomy (specifically, the rectum). The viewer can see a yellow, murky broth filled with wriggling creatures.

The doctor proceeds to extract the contents. The "soup" is revealed to be live eels—specifically small, slippery swamp eels—swimming inside the patient's body. The doctor pulls them out one by one. The visual is grotesque and surreal, looking like a magic trick gone wrong.