CHAPTER 15 -Abdominal Pain
Acute Abdominal Pain
General Principles
• Diagnosing acute abdominal pain is challenging; requires careful
history and physical exam to distinguish urgent surgical from
nonoperative conditions.
• Pain severity does not always correlate with disease severity.
• Many patients have self-limited conditions, but subtle
symptoms can indicate catastrophic disease.
Mechanisms of Abdominal Pain
• Parietal Peritoneal Inflammation
• Steady, localized, aching pain.
• Exacerbated by palpation, coughing, or movement.
• Common causes: gastric/duodenal perforation, peritonitis,
pancreatic juice leakage.
• Leads to reflex muscle spasm over inflamed area.
• Obstruction of Hollow Viscera
• Colicky/intermittent pain, less localized than peritonitis.
• Small-bowel obstruction: poorly localized,
periumbilical/supraumbilical.
• Colonic obstruction: infraumbilical pain, radiates to lumbar
region.
• Biliary colic (misnomer): steady RUQ pain radiating to
back/scapula.
• Ureteral obstruction: severe flank/suprapubic pain radiating
to groin/genitalia.
• Vascular Disturbances
• Mesenteric ischemia: pain out of proportion to exam
findings.
• Rupturing AAA: pain radiating to sacrum, flank, or genitalia.
• Abdominal Wall Pain
• Constant, aching, worsens with movement or pressure.
• Example: rectus sheath hematoma (often with
anticoagulation).
Referred Pain
• Abdominal pain may be referred from thoracic, spinal, or genital
conditions. Approach to the Patient with Abdominal Pain
• Examples: Urgency and Initial Steps
• MI, pneumonia, pericarditis, esophageal disease → • Most abdominal pain cases allow for an orderly evaluation.
mimic abdominal pain. • Exception: exsanguinating intraabdominal hemorrhage (e.g.,
• Diaphragmatic pleuritis → RUQ or supraclavicular pain. ruptured aneurysm) → requires immediate surgery.
• Spinal nerve compression → worsens with cough/sneeze, • Delay for unnecessary tests can be fatal.
dermatomal distribution. • In contrast, intraluminal GI bleeding is usually managed
• Testicular/seminal vesicle disease → dull, aching nonoperatively.
abdominal discomfort.
Diagnosis and History
Metabolic Causes (“Abdominal Crises”) • Acute pain: diagnosis often possible; chronic pain: more
• Mimic intraabdominal disease. challenging (IBS is common).
• Examples: • History is crucial: chronological sequence of events often more
informative than pain location.
• Porphyria, lead colic → severe cramping pain.
• Extraabdominal causes (cardiac, pulmonary, GU) must be
• Diabetic ketoacidosis/uremia → nonspecific abdominal considered.
pain.
• Analgesia should not be withheld; it does not obscure
• C1 esterase deficiency (angioedema) → severe recurrent diagnosis.
abdominal pain.
• In women: obtain menstrual and pregnancy history (physiologic
• Black widow spider bite → intense abdominal and back changes in pregnancy can alter anatomy/labs).
pain with rigidity.
Physical Examination
Immunocompromised Patients
• Careful inspection (facies, posture, breathing) offers important
• Evaluation is very difficult; signs may be muted. clues.
• Causes include: • Exam should be gentle and thorough: rough palpation may
• Opportunistic infections (CMV, mycobacteria, protozoa, obscure findings.
fungi). • Rebound tenderness: best assessed via gentle percussion or
• Splenic abscess (Candida, Salmonella). cough test, not forceful palpation.
• Acalculous cholecystitis in AIDS or critically ill patients. • Pelvic and rectal exams are mandatory in abdominal pain
• Neutropenic enterocolitis (typhlitis) after chemotherapy. evaluation.
• Graft-versus-host disease post-transplant. • Abdominal signs may be minimal but highly significant.
• Auscultation is of limited diagnostic value; normal bowel sounds
Neurogenic & Functional Causes may occur even in major catastrophes.
• Neurogenic pain:
Laboratory Evaluation
• Burning, localized to peripheral nerve distribution.
• Seen in herpes zoster, nerve compression, diabetes, • WBC count: nonspecific (can be high in many conditions, normal
in perforation).
syphilis.
• Functional pain (IBS):
• Anemia may be more useful, especially with supportive history.
• Chronic, variable location, associated with stress and bowel • Urinalysis: hydration, renal disease, infection.
habit changes • Amylase: nonspecific, elevated in several conditions beyond
Acute Abdominal Pain
General Principles
• Diagnosing acute abdominal pain is challenging; requires careful
history and physical exam to distinguish urgent surgical from
nonoperative conditions.
• Pain severity does not always correlate with disease severity.
• Many patients have self-limited conditions, but subtle
symptoms can indicate catastrophic disease.
Mechanisms of Abdominal Pain
• Parietal Peritoneal Inflammation
• Steady, localized, aching pain.
• Exacerbated by palpation, coughing, or movement.
• Common causes: gastric/duodenal perforation, peritonitis,
pancreatic juice leakage.
• Leads to reflex muscle spasm over inflamed area.
• Obstruction of Hollow Viscera
• Colicky/intermittent pain, less localized than peritonitis.
• Small-bowel obstruction: poorly localized,
periumbilical/supraumbilical.
• Colonic obstruction: infraumbilical pain, radiates to lumbar
region.
• Biliary colic (misnomer): steady RUQ pain radiating to
back/scapula.
• Ureteral obstruction: severe flank/suprapubic pain radiating
to groin/genitalia.
• Vascular Disturbances
• Mesenteric ischemia: pain out of proportion to exam
findings.
• Rupturing AAA: pain radiating to sacrum, flank, or genitalia.
• Abdominal Wall Pain
• Constant, aching, worsens with movement or pressure.
• Example: rectus sheath hematoma (often with
anticoagulation).
Referred Pain
• Abdominal pain may be referred from thoracic, spinal, or genital
conditions. Approach to the Patient with Abdominal Pain
• Examples: Urgency and Initial Steps
• MI, pneumonia, pericarditis, esophageal disease → • Most abdominal pain cases allow for an orderly evaluation.
mimic abdominal pain. • Exception: exsanguinating intraabdominal hemorrhage (e.g.,
• Diaphragmatic pleuritis → RUQ or supraclavicular pain. ruptured aneurysm) → requires immediate surgery.
• Spinal nerve compression → worsens with cough/sneeze, • Delay for unnecessary tests can be fatal.
dermatomal distribution. • In contrast, intraluminal GI bleeding is usually managed
• Testicular/seminal vesicle disease → dull, aching nonoperatively.
abdominal discomfort.
Diagnosis and History
Metabolic Causes (“Abdominal Crises”) • Acute pain: diagnosis often possible; chronic pain: more
• Mimic intraabdominal disease. challenging (IBS is common).
• Examples: • History is crucial: chronological sequence of events often more
informative than pain location.
• Porphyria, lead colic → severe cramping pain.
• Extraabdominal causes (cardiac, pulmonary, GU) must be
• Diabetic ketoacidosis/uremia → nonspecific abdominal considered.
pain.
• Analgesia should not be withheld; it does not obscure
• C1 esterase deficiency (angioedema) → severe recurrent diagnosis.
abdominal pain.
• In women: obtain menstrual and pregnancy history (physiologic
• Black widow spider bite → intense abdominal and back changes in pregnancy can alter anatomy/labs).
pain with rigidity.
Physical Examination
Immunocompromised Patients
• Careful inspection (facies, posture, breathing) offers important
• Evaluation is very difficult; signs may be muted. clues.
• Causes include: • Exam should be gentle and thorough: rough palpation may
• Opportunistic infections (CMV, mycobacteria, protozoa, obscure findings.
fungi). • Rebound tenderness: best assessed via gentle percussion or
• Splenic abscess (Candida, Salmonella). cough test, not forceful palpation.
• Acalculous cholecystitis in AIDS or critically ill patients. • Pelvic and rectal exams are mandatory in abdominal pain
• Neutropenic enterocolitis (typhlitis) after chemotherapy. evaluation.
• Graft-versus-host disease post-transplant. • Abdominal signs may be minimal but highly significant.
• Auscultation is of limited diagnostic value; normal bowel sounds
Neurogenic & Functional Causes may occur even in major catastrophes.
• Neurogenic pain:
Laboratory Evaluation
• Burning, localized to peripheral nerve distribution.
• Seen in herpes zoster, nerve compression, diabetes, • WBC count: nonspecific (can be high in many conditions, normal
in perforation).
syphilis.
• Functional pain (IBS):
• Anemia may be more useful, especially with supportive history.
• Chronic, variable location, associated with stress and bowel • Urinalysis: hydration, renal disease, infection.
habit changes • Amylase: nonspecific, elevated in several conditions beyond
