In an 80-year-old man presenting with new-onset lower abdominal bloating, what is the appropriate initial assessment and management?

Lower Abdominal Bloating in an 80-Year-Old Male

In an 80-year-old man with new-onset lower abdominal bloating, mechanical bowel obstruction and colorectal malignancy must be excluded first through urgent clinical assessment, laboratory testing, and CT imaging before considering functional causes. 1, 2

Immediate Priority: Exclude Life-Threatening Causes

The age of 80 years places this patient at high risk for serious organic pathology that requires urgent evaluation:

• Obtain vital signs, assess for peritoneal signs, and examine for abdominal distention, tenderness, and bowel sounds to identify signs of obstruction or perforation 1
• Ask specifically about the last bowel movement and passage of flatus, as inability to pass gas suggests mechanical obstruction 1
• Inquire about prior abdominal surgeries (85% sensitivity for adhesive small bowel obstruction if present) 1
• Screen for alarm features including unintentional weight loss >10%, rectal bleeding, anemia, nocturnal symptoms, and progressive worsening 2

Essential Initial Workup

Order complete blood count, comprehensive metabolic panel, and plain abdominal radiography immediately to assess for leukocytosis, electrolyte abnormalities, and bowel gas patterns 1

CT abdomen/pelvis with IV contrast is the highest-yield initial imaging study and should be obtained urgently to exclude:

• Mechanical bowel obstruction (adhesions cause 55-75% of small bowel obstructions in elderly patients) 1
• Colorectal cancer (responsible for 60% of large bowel obstructions) 1
• Volvulus or diverticular disease (account for 30% of large bowel obstructions) 1
• Bowel ischemia, perforation, or abscess 1

Age-Specific Considerations

Patients over age 50 require colonoscopy to exclude colorectal malignancy if initial imaging does not reveal an acute surgical emergency 1

In elderly males, consider colonic pseudo-obstruction (Ogilvie syndrome), which presents with massive colonic distention without mechanical obstruction and can be triggered by medications, metabolic disturbances, or recent illness 3

If Organic Causes Are Excluded

Only after ruling out mechanical obstruction, malignancy, and other serious pathology should functional causes be considered:

• Screen for carbohydrate malabsorption (lactose, fructose) with 2-week dietary restriction trial before ordering breath testing 1
• Obtain tissue transglutaminase IgA with total IgA to exclude celiac disease 1, 2
• Consider small intestinal bacterial overgrowth (SIBO) testing only in refractory cases with glucose or lactulose breath testing 1

Treatment Approach for Functional Bloating

If Rome IV criteria for functional abdominal bloating are met (bothersome symptoms >8 weeks without meeting IBS, constipation, or dyspepsia criteria):

• Refer to a gastroenterology dietitian for low-FODMAP diet trial (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) 1
• Avoid probiotics, as they are not effective for bloating and distention 1
• Consider central neuromodulators (tricyclic antidepressants or SSRIs) to reduce visceral hypersensitivity if symptoms persist 1
• If constipation is present, treat with appropriate laxatives (osmotic agents, secretagogues like linaclotide or lubiprostone) 1, 4

Critical Pitfalls to Avoid

Do not attribute bloating to functional causes in an 80-year-old without first excluding malignancy and obstruction through imaging and endoscopy 1, 2

Do not code as IBS (K58.x) unless abdominal pain is specifically related to defecation with altered bowel habits 2

Do not delay surgical consultation if imaging reveals bowel obstruction, as elderly patients have higher morbidity and mortality from delayed intervention 1

Recognize that up to 50% of patients may have overlapping conditions requiring multiple diagnostic codes and treatment approaches 2