What is the proper procedure for performing a gastrointestinal (GI) assessment?

How to Perform a GI Assessment

Systematic Physical Examination

Begin with inspection of the abdomen for distension, visible peristalsis, pulsations, skin changes, surgical scars, and asymmetry. 1 Note any signs of peritonitis including guarding, rebound tenderness, or rigidity which may indicate perforation. 1

Auscultation

• Listen for bowel sounds in all four quadrants, noting character, frequency, and pitch. 1
• Absent bowel sounds suggest peritonitis or ileus. 1
• Hyperactive, high-pitched bowel sounds indicate early bowel obstruction. 1
• While bowel sounds remain an important indicator of GI function, only 11.4% of nurses and 47.6% of doctors can make correct clinical judgments based on auscultatory findings alone, so this should not be the sole determinant. 2

Percussion

• Percuss all four quadrants to detect abnormal fluid, masses, or organomegaly. 1
• Assess for shifting dullness and fluid thrill when ascites is suspected. 1
• Identify tympany associated with bowel distension or pneumoperitoneum. 1

Palpation

• Begin with light palpation away from areas of reported pain, progressing to deeper palpation. 1
• Assess for masses, organomegaly, tenderness, guarding, and rebound tenderness. 1
• Perform special maneuvers as indicated: Murphy's sign for cholecystitis, psoas sign for appendicitis, obturator sign for pelvic inflammation. 1
• Digital rectal examination should be performed when indicated, especially for suspected lower GI pathology. 1

Clinical examination may be unreliable in patients with excess skin or flaccid abdomen (such as post-bariatric surgery patients), so maintain a lower threshold for imaging in these populations. 1

Symptom Documentation

List symptoms in order of importance to the patient and record all current medications, especially opioids and cyclizine which can affect GI motility. 3

Key symptoms to document include:

• Abdominal pain (location, character, duration, radiation) 3
• Distension 3
• Nausea/vomiting 3
• Constipation 3
• Diarrhea 3
• Weight loss 3

For standardized assessment, validated tools include the CDAI (Crohn's Disease Activity Index) and HBI (Harvey-Bradshaw Index) for inflammatory bowel disease, though in clinical practice gastroenterologists typically rely on global clinical judgment. 3

Nutritional Assessment

Measure height and weight, ask usual weight in health, and document weight change over the last 2 weeks, 3 months, and 6 months to calculate BMI and percentage weight loss. 3

Additional nutritional measures if undernourished or steatorrhea present:

• Vitamins A, E, D 3
• INR 3
• Iron, ferritin 3
• B12, red blood cell folate 3
• Selenium, zinc, copper 3

Laboratory Assessment

Complete blood count, electrolytes, liver enzymes, renal function (including potassium and magnesium), bone chemistry, thyroid function, glucose, and inflammatory markers (ESR, CRP) are mandatory. 3, 1

Additional testing based on clinical suspicion:

• Anti-tissue transglutaminase for coeliac disease 3
• Myeloma screen 3
• Serum albumin and pre-albumin to assess nutritional status and inflammation 1
• Fecal calprotectin as a marker of intestinal inflammation 3
• Stool analysis, culture, and C. difficile toxin testing 3
• Leukocytosis, neutrophilia, elevated amylase, and lactic acidosis may suggest perforation or necrosis 1

Imaging Studies

CT scan with IV contrast is the recommended primary imaging study for suspected abdominal pathology, with superior sensitivity (93-96%) and specificity (93-100%). 1

Imaging Algorithm:

• First-line: CT abdomen/pelvis with IV contrast for most acute presentations 1
• Alternative: Abdominal ultrasound as screening test with moderate sensitivity (88%) when CT unavailable 1
• Avoid: Plain abdominal X-rays have limited sensitivity (74-84%) and specificity (50-72%); use only when other modalities unavailable 1

Specific Clinical Scenarios:

• Bowel obstruction: CT scan preferred; water-soluble contrast enema if CT unavailable 1
• Perforation: CT scan for stable patients; do not delay surgery if clear signs of diffuse peritonitis 1
• Pregnant patients: Ultrasound and MRI to limit radiation exposure 1
• Appendicitis: Helical CT abdomen/pelvis with IV contrast 1
• Female childbearing age: Pregnancy testing before ionizing radiation 1

For small bowel evaluation specifically:

• MR enterography (≥1.5T) or CT enterography (≥16 slices, ideally 64+) with oral contrast preparation 3
• Patients should fast from solids 4-6 hours before, with hyperosmolar oral agents (mannitol, PEG, sorbitol) ingested 45 minutes before examination 3

Endoscopic Assessment

Ileocolonoscopy with visualization of terminal ileum and all colonic segments should be performed at baseline, with two biopsies of every segment including normal and abnormal areas. 3

• Upper GI endoscopy and biopsies are useful in pediatric patients and adults with upper GI symptoms 3
• Video capsule endoscopy is recommended when ileocolonoscopy and imaging are negative but high clinical suspicion remains 3
• Device-assisted enteroscopy (single or double-balloon) requires 12-hour fasting for oral approach, standard colonoscopy prep for retrograde approach, and deep sedation or general anesthesia 3, 4
• Always use CO2 insufflation instead of room air for device-assisted enteroscopy to improve intubation depth and reduce post-procedural discomfort. 3, 4

Critical Pitfalls to Avoid

Do not delay surgical exploration if there is high clinical suspicion and alarming signs/symptoms, even with negative radiological assessment. 1 CT scan should never expose the patient to unsafe delays in treatment for conditions requiring immediate intervention. 1

• Clinical examination is unreliable in post-bariatric surgery patients due to excess skin and flaccid abdomen 1
• Early involvement of a surgeon is required in cases of suspected perforation 1
• Perform simple bedside assessment of orthostatic pulse rate change (lying to standing) to identify postural orthostatic tachycardia syndrome in patients with autonomic dysfunction 3
• Consider autonomic neuropathy if orthostatic, pupillary, or sudomotor dysfunction accompanies dysmotility 3