# Seminar 06: Abdominal Emergencies ## Year 3: Emergency Medicine Clerkship --- ## Learning Objectives By the end of this seminar, students will be able to: 1. Identify surgical abdominal emergencies 2. Evaluate acute abdominal pain systematically 3. Diagnose and manage appendicitis and cholecystitis 4. Recognize bowel obstruction and perforation 5. Manage gastrointestinal bleeding 6. Apply appropriate imaging strategies --- ## Seminar Outline ### I. Approach to Abdominal Pain The systematic approach to abdominal pain begins with a thorough history that explores the location, quality, timing, and severity of pain. Location provides critical diagnostic information, as right upper quadrant pain suggests biliary or hepatic pathology while right lower quadrant pain raises concern for appendicitis. The quality of pain offers diagnostic clues, with sharp pain suggesting peritoneal irritation, crampy pain indicating hollow viscus obstruction, and burning pain associated with peptic ulcer disease. Temporal characteristics help distinguish surgical emergencies from more benign conditions, as sudden onset suggests perforation or vascular catastrophe while gradual progression is typical of inflammatory processes. The physical examination provides essential diagnostic information that complements the history. Assessment for guarding differentiates voluntary guarding, which patients can relax with reassurance, from involuntary guarding, which indicates peritoneal irritation and cannot be suppressed. Rigidity represents the most concerning finding and strongly suggests peritonitis requiring surgical evaluation. Rebound tenderness, while classically taught, causes unnecessary patient discomfort and can be assessed more gently through percussion tenderness. Bowel sounds vary from hyperactive in early obstruction to absent in advanced ileus or peritonitis. Red flag findings mandate immediate action and surgical consultation. Hemodynamic instability with abdominal pain suggests intra-abdominal hemorrhage, sepsis from perforation, or mesenteric ischemia. Rigidity with fever indicates peritonitis and likely requires emergent surgical intervention. Pain that is disproportionately severe compared to physical findings classically suggests mesenteric ischemia, one of the most time-sensitive abdominal emergencies. A pulsatile abdominal mass in a patient with pain and hypotension represents ruptured abdominal aortic aneurysm until proven otherwise. Imaging strategy depends on clinical presentation and suspected diagnosis. Plain radiography rapidly identifies free air under the diaphragm suggesting perforation, air-fluid levels in obstruction, and radiopaque foreign bodies. Computed tomography with contrast provides the most comprehensive evaluation and should be obtained when the diagnosis is uncertain or to characterize the extent of pathology. Ultrasound serves as first-line imaging for right upper quadrant pain, appendicitis in children and pregnant women, and abdominal aortic aneurysm. Every reproductive-age woman with abdominal pain requires a pregnancy test before imaging to evaluate for ectopic pregnancy. Panel A: Anatomic diagram showing abdominal quadrants with differential diagnoses by location. Panel B: Physical examination techniques demonstrating guarding, rebound, and percussion tenderness. Panel C: Algorithm for imaging selection based on clinical presentation. Panel D: Red flag findings requiring immediate surgical consultation. --- ### II. Appendicitis Appendicitis remains one of the most common surgical emergencies encountered in the emergency department. The classic presentation involves periumbilical pain that migrates to the right lower quadrant as inflammation progresses to involve the parietal peritoneum. Anorexia is nearly universal and precedes or accompanies the onset of pain in most cases. Nausea and vomiting typically develop after pain onset, and this temporal sequence helps distinguish appendicitis from gastroenteritis where vomiting often precedes pain. Low-grade fever develops as inflammation progresses, with high fever suggesting perforation or abscess formation. Physical examination reveals several classic signs of appendicitis, though no single finding is pathognomonic. McBurney's point tenderness, located one-third of the distance from the anterior superior iliac spine to the umbilicus, represents the most reliable finding. Rovsing's sign, right lower quadrant pain elicited by palpation of the left lower quadrant, suggests peritoneal irritation. The psoas sign produces pain with hip extension in retrocecal appendicitis, while the obturator sign causes pain with hip flexion and internal rotation when the appendix lies near the obturator internus. Atypical presentations occur with retrocecal appendices, pelvic appendices in women, and during pregnancy when the enlarging uterus displaces the appendix superiorly. Diagnostic evaluation combines clinical assessment with imaging in most cases. Clinical diagnosis alone may be sufficient in young men with classic presentations and high pretest probability. Risk stratification using the Alvarado score helps guide the need for imaging and disposition. CT scan provides sensitivity exceeding 95% and specificity approaching 95%, with findings including appendiceal diameter greater than 6 mm, wall thickening, periappendiceal stranding, and appendicolith. Ultrasound serves as first-line imaging in children and pregnant women to avoid radiation exposure, with MRI reserved for pregnant patients when ultrasound is inconclusive. Management of appendicitis has traditionally been surgical appendectomy, preferably via laparoscopic approach. Perioperative antibiotics covering enteric flora should be administered, typically cefoxitin or the combination of ceftriaxone and metronidazole. Perforated appendicitis with abscess may benefit from initial percutaneous drainage with interval appendectomy after inflammation resolves. Emerging evidence supports antibiotic-only treatment for selected patients with uncomplicated appendicitis, though most experts still recommend appendectomy as definitive therapy given the risk of recurrence with conservative management. Panel A: Anatomic diagram showing appendiceal positions including retrocecal and pelvic variants. Panel B: Physical examination signs including McBurney's point, psoas sign, and obturator sign. Panel C: CT findings of appendicitis with appendicolith and periappendiceal inflammation. Panel D: Management algorithm including surgical and conservative approaches. --- ### III. Biliary Disease Biliary colic represents the mildest form of symptomatic cholelithiasis and occurs when gallstones temporarily obstruct the cystic duct. Patients experience episodic right upper quadrant or epigastric pain, often precipitated by fatty meals that stimulate gallbladder contraction. Pain typically lasts less than six hours and resolves completely between episodes without fever or systemic symptoms. Ultrasound demonstrates gallstones without evidence of gallbladder wall thickening or pericholecystic fluid. Management includes pain control, dietary modification with fat restriction, and referral for elective cholecystectomy to prevent progression to more serious complications. Acute cholecystitis develops when cystic duct obstruction persists, causing gallbladder distension, wall inflammation, and potential infection. Pain is more severe and persistent than biliary colic, lasting longer than six hours and often accompanied by fever. Murphy's sign, inspiratory arrest during right upper quadrant palpation due to contact between the inflamed gallbladder and the examining fingers, provides the most specific physical finding. Laboratory evaluation reveals leukocytosis and may show mild elevation of hepatic transaminases. Ultrasound findings supporting the diagnosis include gallstones, gallbladder wall thickening greater than 3 mm, and pericholecystic fluid, while HIDA scan demonstrating non-visualization of the gallbladder confirms cystic duct obstruction when ultrasound is equivocal. Ascending cholangitis represents a life-threatening infection of the biliary system caused by obstruction of the common bile duct, most commonly from choledocholithiasis. Charcot's triad of fever, right upper quadrant pain, and jaundice is present in approximately 70% of cases. Reynolds' pentad adds hypotension and altered mental status to Charcot's triad, indicating severe sepsis with high mortality. Laboratory findings include elevated bilirubin, alkaline phosphatase, and often transaminases. Emergent biliary decompression via ERCP is essential, as mortality increases dramatically with delayed drainage. Treatment of biliary disease varies by severity and presentation. Biliary colic requires elective cholecystectomy after pain control and dietary counseling. Acute cholecystitis mandates hospital admission with NPO status, intravenous fluids, and antibiotics covering enteric gram-negative organisms and anaerobes, followed by cholecystectomy preferably within 72 hours of presentation. Delayed surgery is associated with increased technical difficulty and complication rates. Cholangitis requires emergent ERCP for biliary decompression in addition to broad-spectrum antibiotics, with cholecystectomy performed after resolution of acute infection. Panel A: Ultrasound images comparing normal gallbladder, biliary colic with stones, and acute cholecystitis with wall thickening. Panel B: Clinical spectrum from biliary colic through cholecystitis to cholangitis. Panel C: HIDA scan showing non-visualization in acute cholecystitis. Panel D: Treatment algorithm based on biliary disease severity. --- ### IV. Bowel Obstruction Small bowel obstruction results most commonly from adhesions following prior abdominal surgery, which accounts for approximately 75% of cases. Other causes include hernias, which should always be sought on physical examination, malignancy, and inflammatory strictures from Crohn's disease. Patients present with crampy abdominal pain, nausea, vomiting that may become feculent in distal obstruction, abdominal distension, and obstipation. Physical examination reveals a distended abdomen with hyperactive or high-pitched bowel sounds in early obstruction, progressing to diminished sounds as the bowel fatigues. Large bowel obstruction occurs most frequently from colorectal malignancy, followed by volvulus and complicated diverticular disease. Abdominal distension is more prominent than in small bowel obstruction, while vomiting may be less pronounced or absent, particularly in distal obstruction with a competent ileocecal valve. The risk of cecal perforation increases significantly when cecal diameter exceeds 12 cm. Sigmoid volvulus classically occurs in elderly, institutionalized, or neurologically impaired patients and produces the characteristic "coffee bean" or "bent inner tube" sign on plain radiography. Diagnostic imaging begins with plain abdominal radiography, which demonstrates dilated loops of bowel with air-fluid levels. Small bowel is identified by central location and valvulae conniventes that cross the entire lumen, while large bowel is peripheral with haustral markings that only partially cross the lumen. CT scan with contrast identifies the transition point where dilated bowel meets decompressed bowel, determines the cause of obstruction, and evaluates for complications including strangulation. CT findings concerning for strangulation include bowel wall thickening, mesenteric haziness, and pneumatosis intestinalis. Initial management of bowel obstruction is conservative in most cases of partial or simple obstruction. Patients should receive nothing by mouth, have a nasogastric tube placed for decompression, and receive aggressive intravenous fluid resuscitation to replace third-space losses. Electrolyte abnormalities, particularly hypokalemia and hypochloremia from vomiting, require correction. Surgical intervention is indicated for complete obstruction, failure of conservative management after 24-48 hours, or signs of strangulation. Strangulated bowel represents a surgical emergency, with clinical indicators including constant rather than crampy pain, localized tenderness with peritoneal signs, fever, tachycardia, and leukocytosis. Panel A: Plain radiograph showing small bowel obstruction with dilated loops and air-fluid levels. Panel B: CT images demonstrating transition point and differentiation of simple from strangulated obstruction. Panel C: Radiographic appearance of sigmoid volvulus with coffee bean sign. Panel D: Management algorithm for small bowel obstruction including surgical indications. --- ### V. Gastrointestinal Bleeding Upper gastrointestinal bleeding originates proximal to the ligament of Treitz and presents with hematemesis, coffee-ground emesis, or melena. The most common causes include peptic ulcer disease, esophageal or gastric varices, Mallory-Weiss tears, and erosive gastritis. Risk stratification using validated scoring systems such as Glasgow-Blatchford or AIMS65 helps determine the need for admission, ICU-level care, and timing of endoscopy. Initial management prioritizes hemodynamic stabilization with two large-bore intravenous lines, crystalloid resuscitation, and preparation for blood transfusion including type and screen or crossmatch. Lower gastrointestinal bleeding presents with hematochezia or maroon-colored stool and originates distal to the ligament of Treitz. Common causes include diverticulosis, angiodysplasia, hemorrhoids, and colorectal malignancy. Importantly, massive upper GI bleeding can present with hematochezia due to rapid transit, and unstable patients with bright red blood per rectum require consideration of upper sources. Most lower GI bleeds are self-limited, with evaluation proceeding to colonoscopy after stabilization and bowel preparation. Variceal bleeding in patients with portal hypertension carries high mortality and requires specific management. Octreotide reduces portal venous pressure and should be administered as a 50 microgram bolus followed by continuous infusion at 50 micrograms per hour. Prophylactic antibiotics, typically ceftriaxone, significantly reduce mortality by preventing spontaneous bacterial peritonitis and other infections. Urgent endoscopy for band ligation or sclerotherapy provides definitive hemostasis. Balloon tamponade using a Sengstaken-Blakemore or Minnesota tube serves as a temporizing measure when endoscopy is delayed or unsuccessful, while transjugular intrahepatic portosystemic shunt (TIPS) is reserved for refractory cases. Transfusion strategy in GI bleeding has evolved based on evidence supporting restrictive thresholds. A hemoglobin threshold of 7 g/dL for transfusion improves outcomes compared to liberal strategies in stable patients. Variceal bleeding represents a special case where overtransfusion may increase portal pressure and worsen bleeding, with a target hemoglobin of approximately 8 g/dL recommended. Coagulopathy from anticoagulation, liver disease, or massive transfusion requires correction with fresh frozen plasma, platelets, or specific reversal agents. Massive transfusion protocols should be activated for patients requiring large-volume resuscitation with balanced ratios of packed red blood cells, plasma, and platelets. Panel A: Endoscopic images of common upper GI bleeding sources including peptic ulcer, varices, and Mallory-Weiss tear. Panel B: Algorithm for risk stratification and initial management of upper GI bleeding. Panel C: Management of variceal bleeding including pharmacotherapy and endoscopic intervention. Panel D: Transfusion thresholds and massive transfusion protocol activation criteria. --- ### VI. Diverticular Disease Acute diverticulitis occurs when diverticula, outpouchings of colonic mucosa through the muscular wall, become inflamed or infected. The classic presentation includes left lower quadrant pain, often described as "left-sided appendicitis," accompanied by fever and leukocytosis. Patients may report changes in bowel habits including constipation or diarrhea, and urinary symptoms can occur with inflammation adjacent to the bladder. Physical examination reveals left lower quadrant tenderness, though right-sided diverticulitis occurs more commonly in Asian populations. CT scan with intravenous contrast represents the diagnostic imaging modality of choice for suspected diverticulitis. Findings include colonic wall thickening, pericolonic fat stranding, and the presence of diverticula. The CT also identifies complications including abscess formation, perforation with free air, fistula to adjacent structures, and obstruction from stricture. Staging of diverticulitis severity guides management decisions, with uncomplicated disease showing inflammation without abscess or perforation. Management of uncomplicated diverticulitis has evolved, with growing evidence that antibiotics may not be necessary for all cases. When antibiotics are prescribed, outpatient regimens include ciprofloxacin plus metronidazole or amoxicillin-clavulanate, while inpatient treatment typically uses ceftriaxone plus metronidazole or piperacillin-tazobactam. Duration of therapy is generally 7-10 days, though shorter courses may be adequate. Bowel rest with clear liquid diet advancing as tolerated accompanies antibiotic therapy. Complicated diverticulitis requires more aggressive management tailored to the specific complication. Abscesses smaller than 3 cm often respond to antibiotics alone, while larger collections require percutaneous drainage with antibiotic coverage. Free perforation with diffuse peritonitis mandates emergent surgical intervention, typically requiring sigmoid resection with colostomy (Hartmann procedure). Fistulas to bladder, vagina, or skin represent indications for elective surgical resection. Following resolution of acute diverticulitis, colonoscopy should be performed in 6-8 weeks to exclude underlying malignancy, and high-fiber diet is recommended to reduce recurrence risk. Panel A: CT images showing uncomplicated diverticulitis with wall thickening and fat stranding. Panel B: CT findings of complicated diverticulitis including abscess and perforation. Panel C: Management algorithm based on diverticulitis classification and severity. Panel D: Surgical options for complicated diverticulitis including percutaneous drainage and Hartmann procedure. --- ### VII. Mesenteric Ischemia Acute mesenteric ischemia represents one of the most challenging and time-sensitive abdominal emergencies, with mortality rates exceeding 60-80% even with optimal treatment. The classic presentation features severe abdominal pain that is dramatically out of proportion to physical examination findings, often described as "pain out of proportion to exam." Risk factors include atrial fibrillation predisposing to arterial embolism, atherosclerotic disease causing arterial thrombosis, hypercoagulable states leading to venous thrombosis, and low-flow states causing non-occlusive mesenteric ischemia (NOMI). The pathophysiology varies by etiology but ultimately results in bowel ischemia and infarction. Arterial embolism, most commonly from cardiac sources, produces sudden onset of severe pain often with rapid progression to bowel necrosis. Arterial thrombosis typically occurs in patients with underlying mesenteric atherosclerosis, sometimes preceded by symptoms of chronic mesenteric ischemia. Mesenteric venous thrombosis has a more insidious onset and is associated with hypercoagulable states, cirrhosis, and intra-abdominal inflammation. NOMI occurs in critically ill patients with hypoperfusion from cardiogenic or septic shock. Diagnosis requires high clinical suspicion given the potential for rapid deterioration. Laboratory findings include elevated lactate, though this is nonspecific and may be normal early in the disease course. CT angiography represents the imaging modality of choice, providing visualization of arterial and venous occlusion as well as bowel wall changes including thickening, lack of enhancement, and pneumatosis intestinalis indicating infarction. Plain radiography may show late findings including thumbprinting from bowel wall edema and air in the bowel wall (pneumatosis) or portal venous system. Management requires aggressive resuscitation, anticoagulation, and urgent vascular surgery consultation. Intravenous fluid resuscitation corrects hypovolemia and supports mesenteric perfusion. Broad-spectrum antibiotics cover enteric flora given the risk of bacterial translocation. Anticoagulation with heparin prevents propagation of thrombosis. Definitive treatment depends on etiology and bowel viability, with options including catheter-directed thrombolysis, surgical embolectomy, mesenteric bypass, and resection of nonviable bowel. Second-look laparotomy may be necessary to reassess bowel viability after revascularization. Panel A: CT angiography showing superior mesenteric artery occlusion with embolic filling defect. Panel B: CT findings of bowel ischemia including wall thickening and pneumatosis. Panel C: Comparison of arterial embolism, arterial thrombosis, venous thrombosis, and NOMI presentations. Panel D: Management algorithm including resuscitation, anticoagulation, and surgical intervention. --- ### VIII. Pancreatitis Acute pancreatitis presents with characteristic epigastric pain radiating to the back, often described as a band-like or boring sensation. Patients frequently report that pain is worse when lying supine and improved when sitting forward. Nausea and vomiting are nearly universal accompanying symptoms. The two most common causes are gallstones, which trigger pancreatitis through transient ampullary obstruction, and alcohol, which has direct toxic effects on pancreatic acinar cells. Other causes include medications, hypertriglyceridemia, post-ERCP inflammation, and idiopathic cases. Diagnosis requires two of three criteria: characteristic abdominal pain, lipase elevation greater than three times the upper limit of normal, and characteristic imaging findings. Serum lipase is more sensitive and specific than amylase and remains elevated longer. CT scan is not necessary for diagnosis in typical cases but should be obtained when the diagnosis is uncertain, presentation is atypical, or the patient fails to improve as expected to evaluate for complications. Abdominal ultrasound should be performed in all patients to evaluate for gallstones as an etiology. Severity assessment helps predict outcomes and guide management intensity. Mild pancreatitis has no organ failure or local complications and typically resolves within a week with supportive care. Moderately severe pancreatitis features transient organ failure lasting less than 48 hours or local complications without persistent organ failure. Severe pancreatitis is defined by persistent organ failure exceeding 48 hours and carries mortality rates of 20-40%. Scoring systems including Ranson's criteria, BISAP, and APACHE II help predict severity, with early markers including elevated BUN, hematocrit, and creatinine on admission. Management of acute pancreatitis centers on aggressive supportive care. Intravenous fluid resuscitation with lactated Ringer's solution is essential, with goal-directed therapy targeting urine output and hemodynamic parameters. Pain control with opioids provides patient comfort. Traditional prolonged NPO status has given way to early enteral nutrition, often within 24-48 hours if tolerated, which maintains gut barrier function and reduces infectious complications. Prophylactic antibiotics are not indicated and should be reserved for documented infected necrosis. Gallstone pancreatitis warrants cholecystectomy during the same hospitalization to prevent recurrence, while severe cases require ICU monitoring for organ failure. Panel A: CT images showing pancreatic edema, peripancreatic stranding, and necrosis. Panel B: Diagnostic criteria and laboratory findings in acute pancreatitis. Panel C: Severity classification with Ranson criteria and BISAP scoring. Panel D: Management algorithm including fluid resuscitation, nutrition, and indications for intervention. --- ### IX. Other Surgical Emergencies Perforated viscus represents a surgical emergency requiring rapid recognition and intervention. Peptic ulcer disease causes the majority of cases, though perforation can occur from diverticulitis, appendicitis, malignancy, or trauma. Patients present with sudden onset of severe abdominal pain, often with a history of preceding symptoms related to the underlying condition. Physical examination reveals generalized peritonitis with rigidity, absent bowel sounds, and hemodynamic instability in severe cases. Upright chest radiograph or CT demonstrates free air under the diaphragm, and management requires emergent surgical exploration after brief resuscitation and broad-spectrum antibiotics. Incarcerated and strangulated hernias occur when bowel or other abdominal contents become trapped within a hernia defect. Incarceration refers to irreducibility without compromised blood supply, while strangulation indicates vascular compromise leading to bowel ischemia. Patients present with a painful, irreducible bulge at the hernia site, often with nausea, vomiting, and obstructive symptoms. Signs suggesting strangulation include fever, overlying skin erythema, and exquisite tenderness. Manual reduction should be attempted for incarcerated hernias without signs of strangulation, while strangulated hernias require emergent surgical exploration. Toxic megacolon represents a life-threatening complication of colonic inflammation from Clostridioides difficile infection, inflammatory bowel disease, or ischemic colitis. The condition is defined by colonic dilation exceeding 6 cm in the setting of systemic toxicity including fever, tachycardia, and leukocytosis. Patients appear severely ill with abdominal distension and often bloody diarrhea. Plain radiography demonstrates the dilated colon, and CT may show wall thickening and complications. Management includes NPO status, nasogastric decompression, intravenous fluids, and antibiotics, with surgical consultation for possible colectomy if medical management fails. Volvulus occurs when the colon twists around its mesentery, causing obstruction and potential vascular compromise. Sigmoid volvulus is most common and typically occurs in elderly, institutionalized, or neurologically impaired patients. Plain radiography reveals the classic "coffee bean" or "omega" sign of the twisted sigmoid. Cecal volvulus is less common and usually requires surgical intervention. Management of sigmoid volvulus begins with endoscopic decompression using flexible sigmoidoscopy in the absence of peritonitis, though recurrence rates are high, making elective surgical resection advisable. Cecal volvulus typically requires surgical intervention with cecopexy or right hemicolectomy. Panel A: Upright chest radiograph and CT demonstrating free intraperitoneal air from perforation. Panel B: Physical examination and imaging of incarcerated inguinal hernia with signs of strangulation. Panel C: Plain radiograph showing toxic megacolon with dilated transverse colon. Panel D: Radiographic appearance of sigmoid volvulus with coffee bean sign and endoscopic decompression. --- ### X. Anorectal Emergencies Perianal abscess develops from infection of anal glands and presents with severe perianal pain, swelling, and a fluctuant mass on examination. The perianal space is most commonly affected, though abscesses can extend to involve ischiorectal, intersphincteric, or supralevator spaces. Patients may have fever and leukocytosis, particularly with larger or deeper collections. Treatment requires incision and drainage, which can often be performed in the emergency department for superficial perianal abscesses. Antibiotics are not routinely necessary unless significant cellulitis is present or the patient is immunocompromised. Patients should be counseled that approximately 30-50% of perianal abscesses will develop a fistula-in-ano requiring additional treatment. Anal fissure causes severe pain during and after defecation, often described as passing broken glass, with bright red blood on the toilet paper or stool surface. Most fissures occur in the posterior midline due to relatively poor blood supply in this region, and fissures located laterally should raise suspicion for inflammatory bowel disease, sexually transmitted infection, or malignancy. Physical examination reveals a linear tear in the anal canal, often with a sentinel pile externally and hypertrophied anal papilla internally in chronic cases. Initial treatment includes fiber supplementation, stool softeners, sitz baths, and topical agents including nitroglycerin or calcium channel blockers to reduce sphincter spasm. Chronic fissures refractory to medical management may require lateral internal sphincterotomy. Hemorrhoids are classified as internal, arising above the dentate line, or external, arising below. Internal hemorrhoids are covered by insensate mucosa and present with painless bright red bleeding, often coating the stool or dripping into the toilet. External hemorrhoids are covered by sensitive anoderm and cause pain only when thrombosed. Thrombosed external hemorrhoids present with sudden onset of severe perianal pain and a visible, tender, bluish mass. If the patient presents within 72 hours of symptom onset with severe pain, excision of the thrombosed hemorrhoid provides rapid relief. Conservative management with sitz baths, fiber, and topical agents is appropriate for less severe cases or presentations beyond 72 hours when symptoms are improving. Fournier's gangrene is a rapidly progressive necrotizing fasciitis of the perineum and genitalia that carries mortality rates of 20-40% even with optimal treatment. Risk factors include diabetes mellitus, immunocompromise, chronic alcoholism, and local trauma or surgery. Patients present with severe perineal pain, swelling, and erythema that rapidly progresses. Crepitus from subcutaneous gas may be palpable, and systemic toxicity develops quickly. Diagnosis is clinical and should not be delayed for imaging, though CT may demonstrate subcutaneous emphysema. Management requires emergent wide surgical debridement, often with multiple returns to the operating room, along with broad-spectrum antibiotics covering gram-positive, gram-negative, and anaerobic organisms. Mortality increases significantly with each hour of delayed surgical intervention. Panel A: Classification of perianal abscesses by anatomic space and surgical drainage approaches. Panel B: Posterior midline anal fissure with sentinel pile and management algorithm. Panel C: Internal versus external hemorrhoids with thrombosed external hemorrhoid appearance. Panel D: Fournier's gangrene clinical presentation and CT findings with surgical debridement extent. --- ## Summary - Appendicitis: periumbilical pain migrating to RLQ, anorexia, CT for diagnosis, laparoscopic appendectomy is definitive treatment - Cholecystitis: RUQ pain >6 hours, positive Murphy's sign, ultrasound showing stones and wall thickening, surgery within 72 hours - Cholangitis: Charcot's triad (fever, RUQ pain, jaundice), emergent ERCP for biliary decompression is life-saving - Small bowel obstruction: adhesions most common cause, crampy pain, vomiting, distension, surgical intervention for strangulation or failed conservative management - Upper GI bleeding: hematemesis or melena, PPI therapy, octreotide and antibiotics for varices, restrictive transfusion threshold of hemoglobin <7 g/dL - Diverticulitis: LLQ pain with fever, CT diagnosis, antibiotics for complicated cases, surgery for perforation or abscess >3 cm - Mesenteric ischemia: pain dramatically out of proportion to examination findings, CT angiography, high mortality even with treatment - Pancreatitis: epigastric pain radiating to back, lipase >3x upper limit of normal, aggressive fluid resuscitation, early enteral nutrition - Perforated viscus: sudden severe pain with rigidity, free air on imaging, emergent surgical exploration required - Fournier's gangrene: necrotizing fasciitis of perineum, emergent surgical debridement is essential, mortality increases with delayed surgery --- ## Key Terms | Term | Definition | |------|------------| | Murphy's sign | Inspiratory arrest during RUQ palpation indicating gallbladder inflammation | | Charcot's triad | Fever, RUQ pain, and jaundice indicating ascending cholangitis | | Reynolds' pentad | Charcot's triad plus hypotension and altered mental status indicating severe cholangitis | | McBurney's point | Point of maximal tenderness in appendicitis, one-third distance from ASIS to umbilicus | | Strangulation | Bowel ischemia from compromised blood supply in hernia or obstruction | | NOMI | Non-occlusive mesenteric ischemia occurring in low-flow states | | Pneumatosis | Air within the bowel wall indicating ischemia or infarction | | Hematochezia | Passage of bright red blood per rectum | | Fournier's gangrene | Necrotizing fasciitis involving the perineum and genitalia | --- *This content is subject to the [MIT License](https://opensource.org/licenses/MIT). © 2024–2026 Hibbert School of Medicine.*