Fertile Ground

Emily (Leisha Hailey) and Nate Weaver (Gale Harold) are a happily married couple living in New York. Nate is a recognized artist, Emily a fashion designer, and the two are expecting their first child. Emily suffers a terrible miscarriage during a dinner party and she is informed that the scarring left on her womb means she will never be able to conceive again.
To give them both a fresh start, Nate and Emily move out into the countryside to Nate's family home, which has been uninhabited for some time. At first enchanted by it, Emily is horrified when a skeleton is discovered on the property, but it is obvious that the body is very old, so no danger can be attached to the house. After Emily discovers an old trunk filled with old baby things in the cellar, she pays a visit to the local Historical Society and is told that the house has a past she and Nate were unaware of. Several suspicious deaths have occurred at the property in the 18th and 19th century, and Nate's aunt had vanished without a trace when the house was new.
Nate grows distant and cold towards Emily as he starts painting again, acting strangely. Tense and isolated, Emily starts to see visions of a woman covered with blood, and faints. After seeing the doctor, who thinks she is suffering from trauma, she gets a phone call to tell her that she is actually pregnant. Ordered to spend the bulk of her pregnancy in bed resting due to the high risk of miscarriage, Emily starts to get bored and frustrated by Nate, who is working longer and longer hours and seems uninterested in her or the coming baby. Emily's visions continue; she organizes a party for her city friends to rid herself of the loneliness. At the party, she believes that Nate's agent is having an affair with him. Later, the agent somehow falls through the window of Emily's studio and is hospitalized. Nate thinks Emily may have pushed her as he saw her walk away from the window after the woman fell.
When Nate is informed that his agent has died, he storms out angrily. Emily reads through a folder of press cuttings left by the Historical Society and discovers that all the women who died at the house were killed by their husbands. Every woman had been pregnant at the time; supposedly, the house "changed" their husbands and turned them evil. Emily has another vision of the dead woman and believes that Nate is coming back to kill her. She calls her best friend, who tells her that she will come and pick her up.
Terrified, Emily hides in her bedroom with a knife when she hears Nate come back into the house. She tries to stab him with the knife but instead stabs her friendâwho had driven back with Nate. Emily climbs up onto the roof to save herself. She believes she is fighting one of the ghosts of the house; they fall from the roof and she stabs him repeatedly. After killing him, Emily realizes she has actually killed Nate.
At the hospital, a scan reveals that Emily is not pregnant although she believes she is. The doctor's phone call, Nate acting strange, and the ghostly visions were all in her head: symptoms of psychosis. Emily is left in a padded room, rocking her imaginary child in her arms.

Question: What reveals Emily is not pregnant?
Answer: Scan