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 and air-fluid levels throughout the small bowel and colon, are consistent with fecal impaction. The patient's response to laxatives and normalization of bowel movements after treatment also support this diagnosis.
- Other Likely diagnoses
- Constipation-induced ileus: The patient's symptoms and CT scan findings could also be consistent with an ileus caused by constipation, particularly given the patient's history of constipation and recent dehydration.
- Medication-induced constipation: The patient's use of opioid pain medication and methamphetamine (desoxyn) could contribute to constipation, and the recent increase in constipation severity could be related to medication side effects.
- Dehydration-induced constipation: The patient's admission of poor hydration in the days leading up to the onset of constipation, combined with the physical findings and response to treatment, suggests that dehydration may have played a role in the development of constipation.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Intestinal obstruction: Although the CT scan suggests that the narrowing in the sigmoid colon may be due to peristalsis related to the impaction, an underlying stricture or mass could not be excluded. Intestinal obstruction is a potentially life-threatening condition that requires prompt diagnosis and treatment.
- Colorectal cancer: Although the patient has no family history of colorectal cancer or polyps, the presence of a possible stricture or mass in the sigmoid colon, as suggested by the CT scan, necessitates consideration of this diagnosis.
- Ischemic bowel: The patient's history of coronary artery disease and the presence of air-fluid levels throughout the small bowel and colon on the CT scan raise the possibility of ischemic bowel, which is a potentially life-threatening condition.
- 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 possible that the patient may have a predisposition to constipation related to a familial component.
- Methamphetamine-induced ischemic colitis: The patient's history of methamphetamine use, although prescribed, could potentially contribute to ischemic colitis, a rare but serious condition.