Differential Diagnosis
- Single most likely diagnosis
- Fecal impaction: The patient's history of mild constipation, recent onset of severe constipation, and inability to pass stool, along with the CT scan findings of a large amount of stool in the distal colon, support this diagnosis. The patient's response to laxatives and normal bowel movements after treatment also suggest fecal impaction.
- Other Likely diagnoses
- Constipation-induced ileus: The patient's symptoms and CT scan findings, including air-fluid levels and proximal colon distension, could also be consistent with an ileus caused by constipation.
- Dehydration-induced constipation: The patient's admission of poor hydration in the days leading up to the onset of constipation, along with the consumption of constipating foods, supports this diagnosis.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Intestinal obstruction: Although the CT scan suggests that an underlying stricture or mass would not be excluded, the patient's response to laxatives and lack of other symptoms make this less likely. However, it is crucial to consider this diagnosis due to its potential severity.
- Colorectal cancer: Despite the patient's lack of family history, colorectal cancer is a significant concern in patients over 50, and the CT scan findings of an area of narrowing in the sigmoid colon warrant consideration of this diagnosis.
- Volvulus: The patient's symptoms and CT scan findings could also be consistent with a volvulus, although this is less likely given the patient's response to laxatives.
- Rare diagnoses
- Parkinson's disease-related constipation: Although the patient's mother has Parkinson's disease, there is no indication that the patient has the disease himself. However, it is worth considering given the potential for genetic predisposition.
- Medication-induced constipation: The patient's use of stimulant medication for ADHD and rosuvastatin for high cholesterol could contribute to constipation, although this is likely not the primary cause of the patient's symptoms.