What is the next step in workup and treatment for a patient presenting with abdominal pain and suspected colorectal pathology?

Next Steps in Workup and Treatment for Abdominal Pain with Suspected Colorectal Pathology

For patients presenting with abdominal pain and suspected colorectal pathology, computed tomography (CT) scan of the abdomen and pelvis with oral and intravenous contrast should be the initial diagnostic test, followed by colonoscopy if indicated by CT findings or clinical presentation. 1

Initial Diagnostic Approach

• CT scan of the abdomen and pelvis with oral and intravenous contrast is highly accurate (sensitivity/specificity 95%) for diagnosing conditions like diverticulitis and should be considered to confirm diagnosis in patients without prior imaging-confirmed diagnosis 1
• Laboratory tests including complete blood count, sedimentation rate, and serum chemistries should be ordered to assess for inflammation and rule out other causes 1
• Stool Hemoccult testing is recommended as a screening measure for occult bleeding 1

Specific Diagnostic Considerations Based on Suspected Pathology

For Suspected Diverticulitis:

• CT scan is the gold standard for confirming diagnosis and evaluating for potential complications such as abscess, perforation, or fistula 1, 2
• Colonoscopy should be delayed by 6-8 weeks after an acute episode of diverticulitis or until complete resolution of symptoms, whichever is longer 1
• Colonoscopy is advised after an episode of complicated diverticulitis and after a first episode of uncomplicated diverticulitis to rule out malignancy (colon cancer risk is 7.9% in complicated diverticulitis and 1.3% in uncomplicated diverticulitis) 1

For Suspected Inflammatory Bowel Disease (IBD):

• Anoscopy should be performed as part of the physical examination for patients with suspected anorectal pathology when feasible and tolerated 1
• Colonoscopy with biopsies is essential for diagnosis of IBD, particularly to differentiate between Crohn's disease and ulcerative colitis 1
• For patients with IBD symptoms, laboratory tests should include inflammatory markers (CRP, ESR), complete blood count, and stool studies to rule out infectious causes 1

For Suspected Irritable Bowel Syndrome (IBS):

• Limited diagnostic workup is appropriate for patients meeting Rome IV criteria for IBS, particularly IBS-C and IBS-M, who are 21 and 11 times more likely respectively to have these conditions than not have them 1
• Colonoscopy should be considered in patients with IBS-D to exclude microscopic colitis, particularly in females ≥50 years with autoimmune disease, nocturnal diarrhea, weight loss, or use of NSAIDs, PPIs, SSRIs, or statins 1

Treatment Approach

For Diverticulitis:

• Uncomplicated diverticulitis: Acetaminophen is recommended as the primary analgesic for pain control 2
• Clear liquid diet during the acute phase helps reduce pain by minimizing mechanical irritation of the inflamed colon 2
• Antibiotics should be used selectively rather than routinely, specifically for patients with comorbidities, frailty, refractory symptoms, vomiting, or elevated inflammatory markers 2
• Complicated diverticulitis (abscess, perforation, fistula) requires antibiotic treatment covering Gram-negative bacteria and anaerobes 1
• Percutaneous drainage should be considered for abscesses larger than 3cm, while smaller abscesses may respond to antibiotic therapy alone 1

For Inflammatory Bowel Disease:

• Active ulcerative colitis: Topical mesalazine or topical steroid combined with oral mesalazine or corticosteroids is recommended for distal disease 1
• Severe ulcerative colitis requires intravenous therapy, close monitoring, and joint management with a colorectal surgeon 1
• For Crohn's disease, treatment depends on disease location, pattern (inflammatory, stricturing, fistulating), and activity 1
• Infliximab should be considered for penetrating ileocecal Crohn's disease following adequate resolution of intra-abdominal abscesses 1

For Irritable Bowel Syndrome:

• For abdominal pain in IBS, antispasmodic (anticholinergic) medications are recommended, particularly when symptoms are exacerbated by meals 1
• Tricyclic antidepressants should be considered if pain is frequent or persistent 1, 3
• Patient education about IBS as a disorder of gut-brain interaction can lead to symptom improvement 1

Special Considerations

• Patients over age 50 with abdominal pain should undergo colonoscopy due to higher pretest probability of colon cancer 1, 4
• For patients with IBD, surveillance colonoscopy should begin 8-10 years after disease onset for extensive colitis or 15-20 years for left-sided disease to monitor for dysplasia or colorectal cancer 5, 6
• Be aware that 17-28% of IBD patients may develop colorectal cancer before the recommended surveillance starting points 6

Common Pitfalls to Avoid

• Do not blindly attribute painless rectal bleeding to hemorrhoids, as it may be a sign of colorectal cancer, IBD, diverticular disease, or angiodysplasia 1
• Avoid delaying treatment with corticosteroids for suspected acute ulcerative colitis while waiting for stool microbiology results 1
• Do not perform colonoscopy during acute diverticulitis due to increased risk of perforation; delay for 6-8 weeks after resolution 1
• Recognize that clinical suspicion of diverticulitis alone is correct in only 40-65% of patients, highlighting the importance of imaging confirmation 1