What is the step‑by‑step abdominal examination and which physical signs indicate specific abdominal pathologies?

Systematic Abdominal Examination and Pathologic Signs

Begin with inspection for distension, visible peristalsis, pulsations, skin changes, surgical scars, and asymmetry, then proceed sequentially through auscultation, percussion, and palpation—always examining away from areas of reported pain first. 1

Step-by-Step Examination Sequence

1. Inspection

• Observe for abdominal distension, which when combined with absence of flatus (90%) and feces (80.6%) suggests large bowel obstruction. 2
• Look for visible peristalsis, pulsations, asymmetry, and surgical scars that may indicate adhesive disease. 1
• Check for body wall ecchymoses: Cullen's sign (periumbilical) or Grey-Turner's sign (flank discoloration) indicate severe acute pancreatitis with retroperitoneal hemorrhage. 3
• Note that clinical examination may be unreliable in post-bariatric surgery patients due to excess skin and flaccid abdomen. 1

2. Auscultation (Perform BEFORE Palpation)

• Listen in all four quadrants for bowel sound character, frequency, and pitch. 1
• Absent bowel sounds suggest peritonitis or ileus. 2, 1
• Hyperactive, high-pitched bowel sounds indicate early bowel obstruction. 1
• Rater agreement for auscultation is acceptable (72% agreement in normal subjects, 64-94% in obstruction), making it a helpful clinical tool in acute abdominal pain. 4

3. 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
• Tympany indicates bowel distension or pneumoperitoneum. 1
• Percussion combined with palpation remains a useful bedside technique for detecting splenic enlargement when clinical suspicion is high. 5

4. 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 based on clinical suspicion:
  • Murphy's sign for cholecystitis 1
  • Psoas sign (increased likelihood of appendicitis when positive) 2
  • Obturator sign 1
• Digital rectal examination should be performed for suspected lower GI pathology, including palpable rectal cancer. 2, 1

Physical Signs Indicating Specific Pathologies

Peritonitis/Perforation

• Diffuse or localized tenderness with guarding and rebound tenderness indicates peritonitis. 2
• Absent bowel sounds are typical of peritonitis. 2
• Fever, tachypnea, tachycardia, and confusion characterize an acutely ill patient with perforation. 2
• The toxic symptoms of peritonitis are usually delayed but are considered an ominous sign. 2

Bowel Obstruction

• Abdominal distension (65.3%), absence of flatus (90%), and absence of feces (80.6%) are the most common findings in large bowel obstruction. 2
• Hyperactive bowel sounds early, progressing to absent sounds later. 2, 1
• Tenderness on examination is present, but peritoneal signs suggest strangulation or ischemia. 2
• Physical examination has only 48% sensitivity for detecting bowel strangulation, even in experienced hands. 2

Appendicitis

• Positive psoas sign, fever, or migratory pain to the right lower quadrant increases likelihood of appendicitis. 2
• Vomiting before pain makes appendicitis unlikely. 2
• Right lower quadrant tenderness with guarding. 2

Acute Pancreatitis

• Epigastric or diffuse upper abdominal tenderness on examination. 3
• Cullen's sign (periumbilical ecchymosis) or Grey-Turner's sign (flank ecchymosis) may be present in severe cases with retroperitoneal hemorrhage. 3

Mandatory Laboratory Assessment

Complete blood count, electrolytes, liver enzymes, and inflammatory markers (CRP) are mandatory in assessing acute abdomen. 1

Specific Laboratory Findings by Pathology:

• Leukocytosis, neutrophilia, elevated amylase, and lactic acidosis suggest perforation or necrosis. 2
• CRP >75 mg/L and WBC >10,000/mm³ suggest peritonitis, though sensitivity and specificity are relatively low. 2
• Elevated urea nitrogen and metabolic alkalosis occur with vomiting and dehydration in obstruction. 2
• Serum lipase >3 times upper limit of normal is diagnostic for acute pancreatitis (preferred over amylase due to higher specificity). 3
• Stool for Clostridium difficile toxin testing is recommended when infectious causes are suspected. 2

Imaging Algorithm

CT scan with IV contrast is the primary imaging study for suspected abdominal pathology, with superior sensitivity (93-96%) and specificity (93-100%). 2, 1

Imaging Hierarchy by Clinical Scenario:

For Suspected Obstruction:

• First-line: Abdominal ultrasound (88% sensitivity) or plain X-ray (74-84% sensitivity) as screening tests. 2
• Definitive: CT scan (93-96% sensitivity, 93-100% specificity) provides optimal information about complications. 2
• If CT unavailable, water-soluble contrast enema is a valid alternative (96% sensitivity, 98% specificity). 2

For Suspected Perforation:

• CT scan is recommended for stable patients to define cause and site of perforation. 2
• However, if there are clear signs of diffuse peritonitis, CT should NOT delay appropriate surgical treatment. 2, 1
• Ultrasound (76% specificity) performs better than plain X-ray but worse than CT. 2

For Pregnant Patients:

• Ultrasound and MRI are preferred to limit radiation exposure. 2, 1
• Low-dose CT can be used in selected cases when diagnosis remains uncertain. 1

For Suspected Appendicitis:

• Helical CT of abdomen and pelvis with IV contrast is recommended. 1
• Staged algorithms using ultrasound first, followed by CT if inconclusive, have been proposed. 2

Critical Pitfalls to Avoid

Do NOT delay surgical exploration if there is high clinical suspicion and alarming signs, even with negative radiological assessment. 1

• Early involvement of a surgeon is required in cases of suspected perforation. 2, 1
• Plain abdominal X-rays have limited value (sensitivity 74-84%, specificity 50-72%) and should only be used when other modalities are unavailable. 2
• CT scan should never expose the patient to unsafe delays in treatment for conditions requiring immediate intervention. 1
• In incomplete bowel obstruction, watery diarrhea may be present and mistaken for gastroenteritis. 2
• Stools may still be present in patients with relatively high obstruction who present early. 2
• Pain is often less prominent in elderly patients with bowel obstruction. 2
• Clinical examination may be unreliable in post-bariatric surgery patients due to excess skin and flaccid abdomen. 1