The Acute Abdomen

Outline Definitions What causes an “acute abdomen” Differential Diagnosis History and physical Labs Diagnostic imaging High Risk Patients with Acute Abdomen

Acute Abdomen Symptoms and signs of acute intra- abdominal disease processes, usually treated best by surgical operation

The Epidemiology of Acute Abdominal Pain 5-10% of all ED visits. Among them, 14-40% patients need surgical intervention. Challenge for emergency physician (EP): About 1/3 have an atypical presentation. If misdiagnosis, mortality rate 2.5 times higher than correct diagnosis in the elderly.

Three Types of Abdominal Pain Visceral Pain Somatic (Parietal) Pain Referred Pain

The Physiology and Mechanisms of Abdominal Pain Visceral Pain Within the muscular walls of hollow organs and the capsules of solid organs. Stimulated primarily by stretching, distension, and excessive contractions. Characteristically deep, dull, aching or cramping, and poorly localized. Usually felt in the midline, unaccompanied by tenderness.

The Physiology and Mechanisms of Abdominal Pain Somatic (Parietal) Pain Afferent fibers: from T6 to L1, more localized. Characteristically sharper, aggravated by stimulation of the parietal peritoneum with movement, coughing, or walking. True parietal pain surgical cause of abdominal pain.

The Physiology and Mechanisms of Abdominal Pain Referred Pain Pain felt a site other than that of the primary noxious stimulus. Occurs in an area supplied by the same neurosegment as the involved organ. Most visceral pain is of this type. Usually intense and most often secondary to an inflammatory lesion. Subdiaphragm disorder~shoulder pain Biliary tract disorder~right shoulder pain Small bowel disorder~back pain

Causes of Acute Abdomen (DDx) Appendicitis Peritonitis Bowel Perforation Pancreatitis Diverticular disease Cholecystitis Perforating Gastric/Duodenal ulcer Ruptured Ectopic Pregnancy Ruptured or hemorrhagic ovarian cyst Pelvic Inflammatory Disease Abdominal Aortic Aneurysm Tubo-ovarian abscess

Acute Abdominal Pain in Patients Under and Over Age 50 Under 50 (6317 cases), % Over 50 (2406 cases), % Nonspecific abd. pain 39.5 Appendicitis 32.5 Cholecystitis 6.3 Obstruction 2.5 Pancreatitis 1.6 Diverticular disease <0.1 Cancer <0.1 Hernia <0.1 Vascular <0.1 Cholecystitis 20.5 Nonspecific abd. Pain 15.7 Appendicitis 15.2 Obstruction 12.5 Pancreatitis 7.3 Diverticular disease 5.5 Cancer 4.1 Hernia 3.1 Vascular 2.3

Important Extra-abdominal Causes of Abdominal Pain Systemic DKA Alcoholic ketoacidosis Uremia Sickle cell disease Porphyria SLE Vasculitis Glaucoma Hyperthyroidism Toxic Methanol poisoning Heavy metal toxicity Scorpion bite Black widow spider bite Thoracic Myocardial infarction/ Unstable angina Pneumonia Pulmonary embolism Herniated thoracic disc (neuralgia) Genitourinary Testicular torison Renal colic Infectious Strep pharyngitis (more often in children) Rocky Mountain Spotted Fever Monocucleosis Abdominal wall Muscle spasm Muscle hematoma Herpes zoster

History of Present Illness O nset P recipitating/ relieving Q uality R adiation S everity T iming Matched to clinical condition Emerges over time and then concentrates (acute appy) Sudden onset (perforated viscous)

High-Yield Historical Questions How old are you? (Advanced age mean increased risk) 2. Describe the position, character,and migration of the pain sudden coupled with weakness or fainting, less acute but still abrupt onset ,or begin gradually and maximize slowly Is the pain constant or intermittent? (Constant pain is worse) Have you ever had this before? (No prior episodes is worse) Did the pain start centrally and migrate to the right lower quadrant? (High specificity for appendicitis) 3. Have you noticed specific aggravating or relieving factors? (Eating, defecation or flatus) 4. Have you ever had abdominal surgery? (Consider obstruction in patients who report previous abdominal surgery)

High-Yield Historical Questions 5. Do you have nausea, vomiting, diarrhea or bowel habit change? (D/D true diarrhea, overflow incontinence or tenesmus) 6. Do you have HIV? (Consider occult and unusual infection, 30% mortality of surgical treatment) 7. How much alcohol do you drink per day? (Consider pancreatitis, hepatitis, or cirrhosis) 8. Are you pregnant? (Test for pregnancy-consider ectopic pregnancy, menstrual history, sexual exposure history) 9. Are you taking antibiotics or steroids? (These may mask infection) 10. Do you have a history of vascular or heart disease, hypertension, or atrial fibrillation? (Consider mesenteric ischemia and abdominal aneurysm)

Physical Examination Overall appearance ( Facial expression, diaphoresis, pallor, and degree of agitation) Walking and recumbent Vital signs Temperature (T > 40 °C or < 35° C  consider abdominal sepsis) Tachycardia Hypotension Inspection: scars, hernias, masses Auscultation ( Hyperactive BS, hypoactive BS or silent BS, Pulsatile bruit) Percussion Palpation : The most critical step Tenderness Rigidity and guarding (Only 21% > 70 y patients with PPU present with epigastria rigidity) “Board-like abdomen” Rectal digital examination rebounding pain

Laboratory Examination CBC & differential Serum electrolyte ( K, Bicarbonate ) Urinalysis ß-HCG – woman of childbearing age Bilirubin, Alk-p, ALT, AST, G-GT – RUQ pain, jaundice Amylase, lipase – epigastralgia PT, APTT EKG, CK – epigastralgia with aged patient

Five Major Categories of Acute Abdomen (BIOPI) Bleeding or rupture of vessels or tumor Ischemia or Infarction Obstruction Perforation Inflammation

Emergency Department Evaluation of Acute Abdomen History Menstruation history (LMP, ovulation, sexual exposure) Rapid pregnancy test: women of childbearing age. Lab: CBC, liver panel, EKG for elderly. Plain KUB: helpful in obstruction; 40% patients invisible free air. Ultrasound and CT scan: aneurysm, cholelithiasis, ectopic pregnancy, and ureterolithiasis.

Diagnostic Imaging

Important Imaging Studies for Acute Abdomen Standing CXR and KUB Ultrasound: for solid organs. CT of abdomen for abscess, free air, vessel, tumor and ischemia bowel.( gold standard for finding acute appendicitis) Angiography: Especially in non-diagnostic ischemia bowel.

Indications for Abdominal Plain Films Suspected Diagnosis Clinical Findings Perforated viscus Sudden-onset pain Rigid abdomen Decreased bowel sounds Bowel obstruction Prior abdominal surgery Abdominal distension Abnormal bowel sounds High risk for obstruction or volvulus Foreign body Mental retardation Psychosis Suspicion of rectal foreign body

Plain Films Upright CXR KUB (kidney/ureter/bladder) “Free” air Calcifications Air/ Fluid levels Reactive bowel patterns Foreign bodies Lateral Decubitus Film

Ultrasound Rapid, safe, low cost Operator dependent Fluid, inflammation, air in walls, masses Liver, GB, CBD, Spleen, Pancreas, Appendix, Kidney, Ovaries, Uterus

CT Scans Better than plain films and US for evaluation of solid and hollow organs Intravenous contrast Oral contrast Per rectal contrast High use in appendicitis, diverticulitis, abscess, pancreatitis

The Identification of High Risk Patients with Acute Abdomen Elderly > 65 y S/S of Shock Peritoneal sign (+) silent bowel sound Pulsatile mass Refractory pain post Tx The immunocompromised. (e.g. HIV) Women of childbearing age. Elevation of Band WBC Fever cause Hypothermia Acute renal failure Not post-surgical obstruction

Emergency Department Management of Acute Abdomen IV volume replacement and NG decompression Antibiotics: indicated if infection is suspected. Narcotic analgesia (?) Timing (?) Pro: Permit a more accurate history and PE. Morphine (2-5 mg IV) Con: Surgeon is hostile to this approach, consultation immediately.

When to Operate ? Peritonitis Abdominal pain/tenderness + sepsis Excluding primary peritonitis Abdominal pain/tenderness + sepsis Acute intestinal ischemia Pneumoperitoneum Make sure pancreatitis is excluded

When NOT to Operate ? Cholangitis Appendiceal abscess Acute diverticulitis + abscess Acute pancreatitis or hepatitis Ruptured ovarian cysts Long standing perforated ulcers? MI, Acute pericarditis PN, pulmonary infarction GE reflux, DKA, Adrenal Insufficiency Acute Porphyria Rectus muscle hematoma Pyelonephritis, Sickle cell crisis

Thank you