sigmoidoscopy

The story

1. Ancient Greekσῖγμᾰ (sîgmă)
2. Proto-Indo-European*weyd-
3. Proto-Indo-European*wéydos
4. Proto-Hellenic*wéidos
5. Ancient Greekεἶδος (eîdos)
6. Ancient Greekσῑγμοειδής (sīgmoeidḗs)
7. Englishsigmoid
8. Proto-Indo-European*speḱ-
9. Proto-Indo-European*spéḱyeti
10. Proto-Hellenic*sképt͏̌omai
11. Ancient Greekσκέπτομαι (sképtomai)
12. Ancient Greekσκοπός (skopós)
13. Ancient Greekσκοπέω (skopéō)
14. English todaysigmoidoscopy

From sigmoid + -o- + -scopy.