What are the possible causes and recommended evaluation for a patient presenting with jelly‑like stools?

Jelly-Like Stools: Causes and Evaluation

Jelly-like stools most commonly represent mucus in the stool, which can occur in both inflammatory and non-inflammatory conditions, requiring a systematic evaluation starting with stool studies and serological testing to differentiate between organic disease and functional bowel disorders.

Understanding the Presentation

Jelly-like stools typically indicate the presence of mucus, which can be classified using the Bristol Stool Chart as types 5-6 (loose, mushy stool with mucus) versus type 7 (watery diarrhea). This distinction is clinically important because only watery stool (type 7) meets the definition of true diarrhea, while types 5-6 represent loose stool that may warrant different management 1.

Initial Evaluation Approach

Essential Blood Tests

The initial workup should include 1, 2:

• Complete blood count to screen for anemia suggesting organic disease 3
• Inflammatory markers (ESR or CRP) to assess for occult inflammation 3
• Celiac serology (IgA tissue transglutaminase with total IgA level) as celiac disease is the most common small bowel enteropathy and can present with mucoid stools 1, 2
• Thyroid-stimulating hormone (TSH) to exclude hyperthyroidism 2
• Electrolytes, liver function tests, iron studies, vitamin B12, and folate 1

Critical Stool Studies

Fecal calprotectin is the recommended initial screening test, with 93-95% sensitivity and 91-96% specificity for differentiating inflammatory bowel disease from non-inflammatory causes 4:

• Values <50 μg/g point toward non-inflammatory etiologies 4
• Values 50-250 μg/g require clinical correlation and may indicate low-grade inflammation 4
• Values >200-250 μg/g predict active inflammation and require endoscopic evaluation 4

Additional stool testing should include 4, 3:

• Stool culture for Clostridioides difficile is mandatory in all new presentations 4
• Stool culture and ova/parasites testing based on geographic area and clinical features 4, 3
• Fecal occult blood testing for screening purposes 4, 3

Differential Diagnosis Framework

Inflammatory Causes

Mucus production increases with mucosal inflammation 1:

• Inflammatory bowel disease (ulcerative colitis or Crohn's disease) - suggested by elevated fecal calprotectin >200 μg/g, elevated CRP/ESR, or alarm features 4
• Microscopic colitis - affects 10% of patients with chronic watery diarrhea and should be considered if symptoms persist despite negative initial workup 2
• Infectious colitis - particularly C. difficile, which must be excluded in all cases 4

Non-Inflammatory Causes

• Irritable bowel syndrome - diagnosis requires exclusion of celiac disease and inflammatory conditions first 2, 5
• Functional bowel disorders with fecal retention - can present with alternating stool consistency and mucus production 6
• Factitious diarrhea from laxative abuse - becomes increasingly common in specialist practice (20% at tertiary centers) and should be screened early 1

Age-Stratified Endoscopic Evaluation

Patients Under Age 45-50

Flexible sigmoidoscopy with biopsies is appropriate if initial blood and stool tests are unrevealing, as the diagnostic yield is not substantially different from colonoscopy in younger patients 1. However, colonoscopy should be performed if 2, 3:

• Alarm features present (blood in stool, anemia, weight loss, fever)
• Elevated inflammatory markers or fecal calprotectin >200 μg/g
• Positive family history of colorectal cancer or inflammatory bowel disease
• Symptoms refractory to treatment after excluding celiac disease

Patients Age 45-50 and Older

Full colonoscopy is recommended as the preferred investigation due to increased risk of colorectal neoplasia 1. Biopsies should be obtained from both affected and normal-appearing areas to exclude microscopic colitis 4.

Critical Pitfalls to Avoid

• Do not dismiss intermediate fecal calprotectin values (50-250 μg/g) without clinical correlation, as mild elevation may indicate subclinical inflammation requiring serial monitoring at 3-6 month intervals 4
• Do not rely solely on normal CRP to exclude active inflammation, as 15-20% of patients fail to mount a CRP response despite active disease 4
• Do not assume IBS diagnosis without first excluding celiac disease with serology, as it is the most common small bowel enteropathy and can mimic functional disorders 1, 2
• Do not overlook factitious diarrhea in patients with extensive negative workups, particularly those with healthcare connections or eating disorder history 1

When to Escalate Evaluation

Proceed to colonoscopy with biopsies regardless of initial test results if 4, 2:

• Hematochezia or alarm features present
• Fecal calprotectin >200-250 μg/g
• Rising calprotectin on serial monitoring suggesting disease flare
• Age ≥45-50 years without prior colorectal cancer screening
• Acute symptom onset in previously well-controlled disease

Special Considerations

In elderly patients (>60 years), maintain high suspicion for alternative diagnoses including colorectal cancer, ischemic colitis, segmental colitis associated with diverticulosis, NSAID-induced pathology, radiation colitis, or microscopic colitis 4. Fecal calprotectin helps prioritize elderly patients with low probability of inflammatory bowel disease for endoscopic evaluation 4.

For patients with persistent symptoms despite negative colonoscopy, consider small bowel evaluation with capsule endoscopy or dedicated small bowel imaging, particularly if celiac serology is positive or there are features suggesting small bowel disease 1.