Final answer:
The nonsegmented worm found during a colonoscopy with the described symptoms is most likely a nematode, a type of round-bodied worm that can cause intestinal issues.
Step-by-step explanation:
A nonsegmented worm found in an individual during a routine colonoscopy, especially with symptoms of abdominal cramps, nausea, and vomiting, is likely a nematode. Nematodes are unsegmented round-bodied worms and include common intestinal parasites like roundworms, pinworms, hookworms, and whipworms. They have a full digestive system and can sometimes cause mild to severe symptoms, depending on the size of the infestation and the specific nematode species.
Tapeworms and flukes, which are part of the phylum Platyhelminthes, are flat-bodied worms; tapeworms are segmented while flukes are non-segmented. However, the typical symptoms associated with these parasites differ from those experienced by the individual in the question, and the description of the organism as nonsegmented yet not a fluke leads to the conclusion that it is likely a nematode.