Per Abdomen Examination

Patient Positioning & Preparation

• Patient lies supine, legs extended, arms resting by the sides
• The entire abdomen must be exposed — from the nipple line to the inguinal ligaments (saphenous openings)
• Examination in good light, preferably daylight
• The patient should be relaxed; a pillow under the knees reduces abdominal wall tension
• The examiner stands to the right of the patient
• Inspect from the side, tangentially, and from each end of the bed

1. INSPECTION

Skin & Subcutaneous Tissue

• Scars: linear scars (healing by first intention) vs. broad/irregular scars (wound infection); note their location to infer previous surgeries
• Erythema: localized redness from hot-water bottle application — marks the site of pain
• Dilated veins:
  • Periumbilical (caput medusae) → portal hypertension/obstruction
  • Lateral flanks (upward flow) → inferior vena cava obstruction
  • To determine direction of flow: compress vein with two index fingers, milk it empty, release one finger at a time — the vein fills rapidly from the direction of flow
• Subcutaneous nodules near umbilicus: may indicate intra-abdominal carcinoma (especially gastric)
• Striae, bruising (Cullen's sign at umbilicus, Grey Turner's sign at flanks in acute pancreatitis)

Umbilicus

• Normally located midway between xiphisternum and symphysis pubis
• Displaced upward → pelvic mass
• Displaced downward → ascites (Tanyol's sign)
• Everted → ascites or large mass
• Tucked in (inverted) → obesity
• Pushed to one side → mass on the contralateral side

Contour of the Abdomen

• Normal: neither retracted nor distended
• Generalised retraction: found in thin/cachectic individuals
• Symmetrical distension — the "5 Fs":
  • Fat (obesity): umbilicus deeply inverted
  • Fluid (ascites): umbilicus everted, flanks full
  • Flatus (gaseous distension): tympanitic
  • Faeces (obstruction/constipation)
  • Foetus (pregnancy)
• Localised distension: upper abdomen (gastric/hepatic/pancreatic enlargement), lower abdomen (uterine/bladder/colonic mass), right iliac fossa (caecal distension in large bowel obstruction — better seen than felt)
• Visceroptosis: undue protrusion of the lower abdomen when the patient stands

Movement with Respiration

• Restricted or absent movement → peritonitis (the abdomen does not move freely with breathing)
• Visible peristalsis: dilated bowel loops may show visible peristaltic waves — significant of obstruction
• In thin patients, normal aortic pulsation may be visible in the epigastrium

Hernia Orifices

• Inspect the umbilical, epigastric, inguinal, and femoral regions for bulges, especially with coughing

2. AUSCULTATION

• Place the stethoscope lightly on the abdomen; listen in more than one quadrant
• Before declaring the abdomen silent, listen for at least 2 minutes

Bowel Sounds

Note: bowel sounds alone are an unreliable sole criterion for obstruction — they must be interpreted alongside other findings.

Vascular Sounds

• Bruit over the aorta (epigastric midline): aortic aneurysm or aortic stenosis
• Renal artery bruit (above the umbilicus, 2 cm lateral): renal artery stenosis (cause of renovascular hypertension)
• Hepatic bruit: hepatocellular carcinoma or alcoholic hepatitis
• Venous hum at the umbilicus (Cruveilhier–Baumgarten sign): portal hypertension with large paraumbilical varices
• Friction rub over the liver or spleen: hepatic/splenic infarction, perihepatitis (Fitz-Hugh–Curtis syndrome)

Stethoscope as a Tender-Detector

3. PERCUSSION

• Begin with cursory light percussion across all four quadrants to map areas of dullness and tympany
• Dullness = solid/fluid; Tympany = gas

Liver Percussion

• Percuss the upper border of liver dullness (normally at the 5th intercostal space in the midclavicular line)
• Percuss the lower border in the midclavicular line (normally at the right costal margin)
• Normal liver span: 6–12 cm in the midclavicular line
• Loss of liver dullness: free gas under the diaphragm (perforated viscus) — a surgical emergency

Splenic Percussion

• Percuss at the 10th rib posterior to the midaxillary line — splenic dullness is distinct from gastric or colonic tympany
• Traube's space (9th–11th ribs in midaxillary line): normally tympanitic; dullness suggests splenomegaly

Ascites Detection by Percussion

1. Flank dullness: percuss from the umbilicus laterally toward the flank — the note changes from tympany to dullness when fluid is reached; mark the level
2. Shifting dullness (most sensitive clinical test): roll the patient to the lateral decubitus position — the dull note shifts downward and the flank becomes resonant (fluid shifts with gravity)
3. Fluid thrill (large ascites): place one hand flat on one flank, flick the other flank — a transmitted fluid impulse is felt; ask an assistant to press a hand edge along the midline to block transmission through the abdominal wall fat

Bladder Percussion

• A distended bladder produces dullness in the suprapubic region, obliterating the normal transverse skin crease

Percussion of Masses

• Dull = solid or cystic (no gas)
• Central/umbilical dullness with resonance in flanks = solid mass
• Flanks dull with central tympany = ascites (gas-containing bowel floats centrally)

4. PALPATION

Principles

• Warm hands, short fingernails
• Patient must be relaxed; examiner kneels to the level of the bed
• Begin in the quadrant farthest from the pain and work toward it last
• Light palpation precedes deep palpation

Light Palpation

• Entire abdomen surveyed gently (1–2 cm depth) with fingers together
• Detects:
  • Superficial tenderness: the patient winces or tenses
  • Guarding (voluntary): patient voluntarily tightens the muscles
  • Guarding (involuntary/rigidity): persistent board-like rigidity despite distraction — indicates peritoneal irritation
  • Superficial masses: hernias, lipomas, subcutaneous hematomas, lymph nodes

Deep Palpation

• Applies 4–6 cm pressure to palpate deep organs
• The four quadrants are systematically examined
• Identifies: hepatomegaly, splenomegaly, renal masses, abdominal aorta, masses (neoplasm, abscess, lymph nodes)
• Neoplasms (liver, gallbladder, pancreas, stomach, intestine, kidney), abscesses (appendicitis, diverticulitis, Crohn disease), and aortic aneurysms may present as deep masses

Signs of Peritoneal Irritation

Palpation of Specific Organs

Liver

• Begin at the right iliac fossa, move toward the costal margin with each inspiration
• Liver edge descends during deep inspiration — felt as a ridge under the fingers
• Note: size (cm below costal margin in MCL), surface texture (smooth vs nodular), edge (sharp vs rounded), consistency (soft, firm, hard), tenderness
• Causes of hepatomegaly: CCF, viral hepatitis, cirrhosis (early), hepatocellular carcinoma, secondaries, malaria, leukaemia, lymphoma

Spleen

• Begin at the RIF (as massive splenomegaly reaches to the RIF)
• Palpate diagonally toward the left costal margin with each inspiration
• Support the left costal margin with the left hand; palpate below the costal margin with the right
• Cannot get above the splenic edge (differentiates from renal mass); has a notch on the medial border; dull to percussion
• Causes of splenomegaly: malaria, portal hypertension, haematological malignancies, infections (EBV, typhoid), haemolytic anaemias

Kidneys (Bimanual)

• Right kidney: right hand in the right loin posteriorly, left hand anteriorly in the right flank
• Can "ballot" the kidney between both hands — ballottement is characteristic of a renal mass
• Key features distinguishing kidney from spleen: can get above the renal mass, resonant to percussion (bowel in front), ballottable, moves with respiration but descends vertically (not diagonally)

Gallbladder

• Palpated below the liver edge at the tip of the 9th costal cartilage (lateral to the MCL)
• Murphy's sign: press under the right costal margin in the MCL; ask patient to inspire deeply — sharp arrest of inspiration due to pain as the inflamed gallbladder descends onto the examining fingers → positive in acute cholecystitis
• Courvoisier's law: a palpable, non-tender gallbladder with jaundice suggests malignant biliary obstruction (not gallstones, which cause a fibrotic, non-distensible gallbladder)

Aorta

• Palpated in the epigastric/para-umbilical region
• Normal aortic pulsation is palpable but narrow
• An expansile pulsatile mass (pulsation in all directions) suggests aortic aneurysm (>3 cm)
• Transmitted pulsation (e.g., from a mass overlying the aorta) pulsates only in one direction

Urinary Bladder

• A distended bladder is a smooth, rounded, dull, midline swelling arising from the pelvis
• May be palpable up to the umbilicus or beyond in chronic retention

5. SPECIAL EXAMINATION

Inguinal/Femoral Regions

• Inspect and palpate the inguinal canal and femoral ring for hernias (ask the patient to cough)
• Examine the external genitalia in males: scrotum, testes, epididymis, vas deferens

Rectal/Pelvic Examination

• Digital rectal examination (DRE) is part of a complete abdominal exam when indicated
• Allows palpation of rectal masses, cervix, pouch of Douglas, prostate, and stool character
• Inspect perianal region: fissures, fistulas, hemorrhoids, skin tags

External Genitalia

• Examine in all patients with acute abdominal pain or urological symptoms

Summary: Sequence of Findings and Their Clinical Significance

Illustrative Images

Necrotizing Fasciitis

Definition

The term was introduced by Wilson (1951–52) to encompass both gas-forming and non-gas-forming necrotizing soft-tissue infections along the fascial plane. Earlier names included "hospital gangrene" (Joseph Jones, 1871), "streptococcal gangrene," and "hemolytic streptococcal gangrene."

Epidemiology

• In the US: approximately 3,800–5,800 admissions/year for necrotizing soft-tissue infections
• Incidence: ~59–76 cases per million patient-years
• Deaths from NF (US, 2003–2013): ~4.8 deaths per million patient-years
• Higher mortality in Black, Hispanic, and Native American individuals
• Pediatric prevalence: ~0.8 per million patient-years (worldwide, 2010–2015)
• Peaks in the neonatal period and in children aged 1–2 years (truncal, often monomicrobial)

Etiology & Pathogenesis

Portal of Entry

• Most cases are community-acquired via breaks in the skin: cuts, scrapes, minor trauma, insect bites, animal bites, IV drug injection sites, prior surgical sites, varicella lesions, burns
• In ~50% of cases, no portal of entry is identified ("cryptic" NF) — infection begins in deep tissues at sites of muscle strain, bruise, or nonpenetrating trauma
• In tropical climates: snake bites (notably Naja atra)

Microbial Mechanism

1. Polymicrobial synergy: Facultative gram-negative organisms lower the oxidation-reduction potential of tissue, enabling anaerobic growth. Anaerobes, in turn, impede phagocyte function and favour aerobic proliferation.
2. Toxin-mediated injury: Clostridial alpha-toxin causes tissue necrosis and cardiovascular collapse. S. aureus and streptococci produce exotoxins triggering TNF and cytokine release → SIRS → septic shock → multi-organ failure.

Classification

Microbiologic Types

The simpler classification — polymicrobial vs. monomicrobial — is most widely used in current literature.

Anatomic Variants

• Cervicofacial/Craniofacial NF: spread from odontogenic infections, peritonsillar abscesses — high mortality given proximity to airway
• Perineal/Genital (Fournier's Gangrene): NF of the perineum, scrotum, and penis; urological/colorectal source; polymicrobial; extremely destructive
• Truncal NF: includes abdominal wall; neonatal NF most frequently involves the abdominal wall and has higher mortality than adult NF
• Limb NF: extremities are most commonly involved; amputation may be required

Clinical Features

Early Signs

• Pain out of proportion to clinical findings — the most important early clue; tenderness extends beyond the area of visible erythema
• Erythema, swelling, warmth, and tenderness spreading rapidly both proximally and distally within 24 hours
• Brawny (woody) oedema of the skin
• Systemic: low-grade fever, tachycardia out of proportion to fever, anxiety, diaphoresis

Progression (24–96 hours)

• Erythema darkens from red → purple → blue
• Appearance of blisters and bullae containing clear yellow or later dark purple/haemorrhagic fluid
• Crepitus (surgical emphysema): caused by gas-producing organisms — present in only 13–31% of patients; its absence does NOT rule out NF
• Skin anaesthesia: characteristic — results from thrombosis of cutaneous nerves and vessels; a dangerous sign of deep necrosis
• Bacteraemia with possible metastatic abscesses

Late Signs (Day 4–5 onwards)

• Frank gangrene of affected skin — black necrotic eschars
• Malodorous serosanguineous ("dishwater") discharge
• Extensive sloughing of skin
• Systemic: septic shock, cardiovascular collapse (especially with V. vulnificus and streptococcal TSS), multi-organ failure, confusion, rapid deterioration of consciousness

Key early warning triad: (1) pain out of proportion, (2) swelling/erythema with brawny oedema, (3) systemic toxicity.

Clinical Photograph

Diagnosis

Bedside Test (Finger Test)

• Lack of bleeding
• Murky "dishwater" discharge
• No resistance to probing (tissue planes dissect easily — the fascial layer separates without resistance)

Laboratory: LRINEC Score

• ≤5: low risk (<50%)
• 6–7: intermediate — raises suspicion
• ≥8: high risk (>75% probability)

⚠️ Important limitation: The LRINEC score ≥6 misses many cases, especially Vibrio infections and cervical NF. Clinical suspicion must always override a low LRINEC score. The score is a screening aid, not a diagnostic criterion.

Imaging

Crucially, even MRI and CT do not definitively exclude NF — a normal imaging study does not rule out the diagnosis if clinical suspicion is high. Surgical exploration remains the gold standard.

Histopathology (Biopsy/Frozen Section)

• Necrosis of fascia and subcutaneous fat
• Polymorphonuclear infiltrate
• Thrombosis of vessels in the subcutaneous tissue
• Gram stain of aspirated fluid: chains of gram-positive cocci with few or no WBCs (in Group A Strep cryptic NF)

Differential Diagnosis

• Severe cellulitis (no fascial involvement, no systemic toxicity)
• Gas gangrene / clostridial myonecrosis (muscle involved, crepitus marked)
• Pyomyositis (abscess in muscle belly, fascia usually spared)
• Trauma with haematoma formation
• Neutrophilic dermatoses (Sweet's syndrome)
• Deep vein thrombosis / phlebitis
• Bursitis

Management

Resuscitation

• Aggressive IV fluid resuscitation — NF lesions drain large volumes
• Close monitoring of vitals, electrolytes, urine output
• ICU admission for haemodynamically unstable patients

1. Surgical Debridement — The Cornerstone

• Radical surgical debridement is the mainstay of treatment — antibiotics alone are insufficient
• Surgical intervention within 24 hours of onset is strongly associated with improved outcomes; delays beyond 24 hours significantly increase mortality
• Debridement must be staged and daily — a single debridement rarely achieves full clearance; daily returns to theatre until no further necrotic tissue is found on surgical exploration
• Amputation may be necessary for severe limb disease; risk is higher in diabetic patients
• Wound closure after final debridement: vacuum-assisted closure (VAC) devices then split-thickness skin grafting

2. Antibiotics (Adjunctive but Crucial)

• Anti-MRSA agent: Vancomycin OR Linezolid OR Daptomycin
• PLUS one of:
  • Piperacillin-tazobactam
  • Carbapenem (imipenem/meropenem)
  • Ceftriaxone + metronidazole
  • Fluoroquinolone + metronidazole

• Penicillin G + Clindamycin (clindamycin suppresses toxin production via ribosomal inhibition even at static doses)

• Final surgical debridement completed
• Afebrile for 48–72 hours
• Clinical stabilization

3. Supportive Care

• Aggressive resuscitation, vasopressors if required
• Blood products for coagulopathy / severe anaemia
• Nutritional support (high protein for wound healing)

4. Hyperbaric Oxygen (HBO)

• Insufficient evidence to support routine use
• Some studies suggest potential benefit; research ongoing — not recommended as first-line

5. IV Immunoglobulin (IVIG)

• Early studies showed some benefit, particularly in streptococcal TSS complicating NF
• No strong evidence to support routine use in NF

Prognosis & Prognostic Factors

• Age >50 years
• Underlying diabetes mellitus or atherosclerosis
• Delay in diagnosis and surgical intervention >7 days
• Infection involving the trunk (vs. extremities)
• Haemodynamic instability / septic shock at presentation
• Vibrio vulnificus or polymicrobial infection
• Neonatal NF (higher mortality than adult)

• Amputation (common with limb disease, especially in diabetics)
• Prolonged hospital course with repeated operations
• Extensive skin grafting requirements
• Long, laborious recovery process following discharge

Summary Table