Fecal Impaction is the Most Likely Diagnosis
In a bedridden patient with home nursing presenting with intestinal obstruction after a fall, fecal impaction (Option D) is the most likely diagnosis. This population has multiple risk factors including immobility, likely medication use, and advanced age that predispose to severe constipation and impaction 1.
Clinical Reasoning for This Patient Population
Why Fecal Impaction is Most Likely
Bedridden patients are at extremely high risk for fecal impaction, which commonly presents with signs of intestinal obstruction 1, 2. The key clinical context here includes:
- Immobility is a primary risk factor - bedridden status dramatically slows gastrointestinal motility 1
- Fecal impaction frequently mimics mechanical obstruction with abdominal distention, pain, and inability to pass stool 2
- The presentation can be identical to other causes of obstruction, making clinical suspicion based on risk factors essential 2
- Elderly bedridden patients often have neuropsychiatric conditions or use medications (antipsychotics, opioids) that further slow bowel motility 1, 2
Why Other Options Are Less Likely
Sigmoid volvulus (Option A) typically occurs in elderly institutionalized patients but presents more acutely with sudden onset of severe pain and massive abdominal distention. While possible, it's less common than fecal impaction in this population 3.
Colorectal cancer (Option B) would typically have a more gradual onset with warning signs like rectal bleeding, weight loss, or change in bowel habits over weeks to months 4. The acute presentation after a fall makes this less likely as the primary diagnosis.
Pseudoobstruction (Option C) is a consideration in bedridden patients, but fecal impaction is far more common and should be excluded first 3. Pseudoobstruction often occurs after surgery, trauma, or with specific metabolic disturbances 4.
Diagnostic Approach
Digital rectal examination is the critical first step - it can immediately identify a fecal impaction in 80% of cases and is both diagnostic and potentially therapeutic 5, 2.
If rectal examination is negative but suspicion remains high:
- CT abdomen/pelvis is the gold standard with approximately 90% accuracy for identifying the level and cause of obstruction 4
- CT can demonstrate a large sigmoid fecalith and any complications like hydronephrosis from mass effect 1
- Plain radiographs have limited value (50-60% sensitivity) and may delay definitive diagnosis 4
Critical Pitfall to Avoid
Fecal impaction can present with overflow diarrhea, which may mislead clinicians into thinking the patient has gastroenteritis rather than obstruction 5. This paradoxical diarrhea occurs when liquid stool passes around the impacted mass and is a particularly dangerous presentation in elderly patients 5.
The diagnosis of fecal impaction should only be made after excluding other mechanical causes of obstruction through appropriate imaging, as the presenting signs are often indistinguishable from other obstructive pathology 2.