Final answer:
Ivy's belief that her kidneys are falling out without further symptoms or medical evidence points to a somatic symptom disorder, a psychological issue where there is excessive anxiety over physical symptoms. This does not align with the nature of PTSD or physical disorders such as kidney stones or spinal cord issues.
Step-by-step explanation:
Ivy may have symptoms associated with somatic symptom disorder. This condition involves excessively thinking about and being anxious about one's physical symptoms to the point where it disrupts daily life. Given Ivy's conviction that her kidneys are falling despite the lack of medical evidence, this might point to a psychological issue rather than a purely physical one such as appendicitis, UTI, or PID, which her doctor mentioned are usually accompanied by additional symptoms. However, her concern does not align with the symptoms or underlying causes of PTSD, which is a reaction to psychological trauma and not typically associated with specific physical pain without a related traumatic event.
In the context of kidney health, while symptoms of kidney stones include severe 'loin to groin' pain and other issues, there is no direct mention of Ivy having such symptoms. Moreover, her doctor's consideration of her past treatment in Vietnam for a compressed spinal cord suggests the symptom is not related to it, as abdominal pain is not usually a result of spinal issues. Thus, based on the given information, somatic symptom disorder seems to be the most likely explanation for Ivy's symptoms.