Approach to abdominal pain Pongkamon Tongpong

Outlines Introduction Types Approach to acute care History taking and physical examination Investigations Differential diagnosis Special settings Cases

Introduction Abdominal pain can be a challenging complaint Benign complaint but it can also herald serious acute pathology Clinicians have to determine which patients can be safely observed or treated symptomatically and which required further investigation or specialist referral Accuracy of history and physical examination for the serious causes of abdominal pain, alone or combined with focused investigations, have yield good results

Outlines Introduction Types Approach to acute care History taking and physical examination Investigations Differential diagnosis Special settings Cases

Types Acute VS Chronic Visceral VS parietal VS referred pain Chronic : duration more than 7 days Visceral VS parietal VS referred pain Surgical VS non-surgical conditions : required surgical management

Types of pain Parietal pain Visceral pain Referred pain

Nerve transmission Two distinct types of afferent nerve fibers (autonomic and somatic nervous system) Unmyelinated C fibers - visceral Myelinated A-δ fibers - somatic-parietal Interplay between the two systems results in a third type of pain, referred pain

VISCERAL PAIN Transmitted by C fibers - muscle, periosteum, mesentery, peritoneum, and viscera Dull, cramping, burning, poorly localized More gradual in onset and longer in duration than somatic pain Usually perceived in the midline, in the epigastrium, periumbilical region, or hypogastrium

Distribution of autonomic nervous system

Abdominal visceral nociceptors Respond to mechanical and chemical stimuli Mechanical signal are stretch Cutting, tearing, or crushing of viscera does not result in pain Stretch receptors are located in muscular layers of hollow viscera Between muscularis mucosa and submucosa Serosa of solid organs, and in the mesentery (adjacent to large vessels)

Mechanoreceptor stimulation Distention of hollow viscus (e.g., intestinal obstruction) Forceful muscular contractions (e.g., biliary pain or renal colic) Rapid stretching of solid organ serosa or capsule (e.g., hepatic congestion) Torsion of mesentery (e.g., cecal volvulus) Tension from traction on mesenteric vessels (e.g., retroperitoneal or pancreatic tumor)

Chemical nociceptors Contained mainly in mucosa and submucosa of hollow viscera Activated directly by substances released Response to local mechanical injury, inflammation, tissue ischemia and necrosis, and noxious thermal or radiation injury

SOMATIC-PARIETAL PAIN Mediated by A-δ fibers Distributed principally to skin and muscle Sudden, well-localized pain, such as that which follows an acute injury Convey pain sensations through spinal nerves Activates local regulatory reflexes and long spinal reflexes Transmitting pain sensation to central nervous system

Somatic-parietal pain Aggravated by movement or vibration Reach spinal cord in peripheral nerves Sixth thoracic (T6) to first lumbar (L1) vertebra

REFERRED PAIN Result from adjacent structures that subsequently migrate away from each other For example, central tendon of the diaphragm begins its development in the neck Shows diaphragmatic irritation from a subphrenic hematoma or splenic rupture may be perceived as shoulder pain (Kehr's sign)

Outlines Introduction Types Approach to acute care History taking and physical examination Investigations Differential diagnosis Special settings Cases

APPROACH TO ACUTE CARE A: Airway B: Breathing C: Circulation If hemodynamic instability is apparent Surgical consultation should be sought immediately Consideration to endotracheal intubation and resuscitation

GI organs KUB organs Genital organs

Outlines Introduction Types Approach to acute care History taking and physical examination Investigations Differential diagnosis Special settings Cases

History taking Onset of pain , frequency, duration Character : visceral pain usually dull, poorly localized. Parietal pain usually sharp and very well localized. Location of pain Radiation of pain Severity of pain Aggravating or relieving factors ex. Food , exertion, defecation, antacid Associated symptoms : fever, N/V, diarrhea, constipation, GI bleeding, jaundice, change in stool and urine color, abnormal vaginal bleeding

History taking Past medical and surgical history Family history of bowel disorder Alcohol intake Medication (included over-the-counter drugs) Menstruation and contraception in women

Physical examination Vital signs General appearance : posture, degree of discomfort, facial expression, breathing pattern Abdominal examination Systemic examination eg. cardiac arrhythmia

Abdominal Examination Inspection - entire abdomen, from the nipple line to the thighs Assessment of bowel sounds and their character At least two minutes and in more than one quadrant Distinguish high-pitched of a mechanical small intestinal obstruction from the more hollow sounds of toxic megacolon

Abdominal Examination Tenderness is detected, an assessment for rebound tenderness to look for evidence of peritonitis Palpation, ask for pain location and that area should be palpated last to detect involuntary guarding and muscle rigidity Patient with rigid abdomen rarely revealed any additional findings (eg. mass) Genital, Rectal, and Pelvic Examinations

Outlines Introduction Types Approach to acute care History taking and physical examination Investigations Differential diagnosis Special settings Cases

LABORATORY DATA Complete blood count, and urinalysis Determination of serum electrolyte, blood urea nitrogen, creatinine, and glucose Urine pregnancy testing in all women of reproductive age with abdominal pain Liver biochemical tests and serum amylase levels for patients with upper abdominal pain or with jaundice

LABORATORY DATA Metabolic acidosis, an elevated serum lactate level, or a depressed bicarbonate level Associated with tissue hypoperfusion and shock Likely to require urgent surgical intervention or intensive care

Imaging High-speed helical CT Sensitivity and specificity of CT scanning for acute appendicitis are 94% and 95%, Negative CT scan in the setting of acute abdominal pain has considerable value in excluding common disorders

Ultrasonography Rapid, bedside test to detect fluid in the abdominal cavity

OTHER DIAGNOSTIC TESTS MRI and radionuclide scanning and endoscopy A secondary role in the evaluation Guided by results of CT or ultrasound

Outlines Introduction Types Approach to acute care History taking and physical examination Investigations Differential diagnosis Special settings Cases

Causes of acute abdominal pain Etiology Patients (%) Non-specific abdominal pain 35 Appendicitis 17 Bowel obstruction 15 Urologic disease 6 Biliary disease 5 Diverticular disease 4 Pancreatitis 2 Medical illnesses 1 Other

Parietal pain

Parietal pain

Visceral pain 1. Epigastrium 2. Mid-abdomen 3. Hypogastrium

Outlines Introduction Types Approach to acute care History taking and physical examination Investigations Differential diagnosis Special settings Cases

Extremes of Age Cause in infancy - intussusception, pyelonephritis, gastroesophageal reflux, Meckel's diverticulitis, and bacterial or viral enteritis In children - Meckel's diverticulitis, cystitis, pneumonitis, enteritis, mesenteric lymphadenitis, and inflammatory bowel disease are prevalent

Extremes of Age In adolescents – PID, IBS and other common causes In children of all ages, two of the most common causes of pain are acute appendicitis and abdominal trauma secondary to child abuse

Pregnancy Develop acute appendicitis and cholecystitis at the same rate as their nonpregnant Placental abruption and pain related to tension on the broad ligament, must be consider Radiation injury to the developing fetus must be considered

Immunocompromised Hosts Neutropenic enterocolitis Drug-induced pancreatitis Graft-versus-host disease Pneumatosis intestinalis Cytomegalovirus (CMV) and fungal infection

HIV associated Primary peritonitis Spontaneous intestinal perforation, usually secondary to CMV infection Tuberculous peritonitis is a consideration

ACUTE APPENDICITIS Overall incidence of appendicitis is approximately 11/10,000 population Typically, begins with prodromal symptoms of anorexia, nausea, and vague periumbilical pain Pain migrates to RLQ and peritoneal signs develop In uncomplicated appendicitis, a low-grade fever to 38 C and mild leukocytosis A higher temperature and WBC are associated with perforation and abscess formation

ACUTE BILIARY DISEASE Range from biliary pain to acute cholecystitis Biliary pain is a syndrome of RUQ or epigastric pain, usually postprandial Caused by transient obstruction of the cystic duct by gallstone Self-limited, generally < 6 hours, persistance in cholecystitis

ACUTE BILIARY DISEASE Dull ache and localized to RUQ or epigastrium Radiate around the back to the right scapula Nausea, vomiting, and low-grade fever are common On examination, right upper quadrant tenderness, guarding, and Murphy's sign are diagnostic Mild elevations in serum total bilirubin and alkaline phosphatase levels

ACUTE BILIARY DISEASE Ultrasound evaluation of RUQ is the key diagnostic test Finding of stones with gallbladder wall thickening, pericholecystic fluid, and sonographic Murphy's sign Diabetic, with WBC over 15,000/mm3, are at particular risk for gangrenous cholecystitis

SMALL BOWEL OBSTRUCTION In pediatric patients, intussusception, intestinal atresia, and meconium ileus In adults, about 70% of cases are caused by postoperative adhesions and incarcerated hernias Small bowel obstruction is characterized by sudden, sharp, periumbilical abdominal pain Nausea and vomiting occur soon after onset of pain

SMALL BOWEL OBSTRUCTION Frequent bilious emesis with epigastric pain is suggestive of high intestinal obstruction Cramping periumbilical pain with infrequent feculent emesis is more typical of distal intestinal obstruction Fever, tachycardia, and orthostatic hypotension Abdominal distention Diffusely tender to percussion and palpation, but peritoneal signs are absent

SMALL BOWEL OBSTRUCTION Plain abdomen reveal dilated loops of small intestine with air-fluid levels Decompressed distal small bowel and colon CT is superior for establishing the diagnosis and location of intestinal obstruction

ACUTE DIVERTICULITIS 80% of affected patients are older than 50 years Usually present with constant, dull, left lower quadrant pain and fever Constipation or obstipation

ACUTE DIVERTICULITIS LLQ tenderness and mass In severe cases, generalized peritonitis may be present CT is reliable in confirming the diagnosis, with a sensitivity of 97% Severity of diverticulitis, as determined by CT, is described using the Hinchey grading system

ACUTE PANCREATITIS Typically begins as acute pain in epigastrium To back or left scapular region Fever, anorexia, nausea, and vomiting are typical Flank or periumbilical ecchymoses (Grey-Turner's or Cullen's sign) Develop in setting of pancreatic necrosis with hemorrhage Extremities are cool and cyanotic

ACUTE PANCREATITIS White blood cell counts of 12,000 to 20,000 Elevated serum and urine amylase levels are usually present within the first few hours of pain Abdominal ultrasonography for identifying gallstones CT is reserved for patients with severe or complicated pancreatitis

PERFORATED PEPTIC ULCER Acutely with excruciating abdominal pain Abdominal examination reveals peritonitis, with rebound tenderness, guarding, or abdominal muscular rigidity Pneumoperitoneum is identified on an abdominal radiograph in 75% of patients

ACUTE MESENTERIC ISCHEMIA More common in superior mesenteric artery than celiac or inferior mesenteric artery Because of less acute angle Acute mesenteric embolism, mesenteric thrombosis, and nonocclusive mesenteric ischemia each account for one third of cases A mortality rate of 60% to 100%

ACUTE MESENTERIC ISCHEMIA Epigastric and periumbilical pain out of proportion Other symptoms - diarrhea, vomiting, bloating, and melena Shock is present in about 25% of cases CT is the best initial diagnostic test

ABDOMINAL COMPARTMENT SYNDROME Elevated intra-abdominal pressure In a patient who survives massive volume resuscitation Resulting visceral or retroperitoneal edema Elevated intra-abdominal pressure in turn compromises visceral perfusion Kidney is particularly prone to underperfusion in this setting Kidney failure may be the first sign of ACS