How does the author use foreshadowing in the novel, Two Wrongs?

When Bill describes his illness to Emmy in dialogue during the final section, he mentions an X-ray, says that the left lung “­is practically gone” (449), and says that “luckily there are no spots” (449) on the other lung. Yet despite being offered these details, the reader does not know Bill’s actual diagnosis. Instead, Fitzgerald foreshadows something ominous without revealing the full truth, which keeps the reader in suspense while preserving a sense of verisimilitude.