| Etiology | Clinical manifestations | Risk factors, common causes, or complications |
| Abdominal aortic aneurysm | - Abdominal, back, or flank pain
- Rupture typically produces acute, severe pain and unstable hypotension from exsanguinating hemorrhage
- If a AAA ruptures into the retroperitoneum and tamponades, a patient can initially present normotensive
- AAAs can cause hematuria and be misdiagnosed as renal colic[1,2]
| - Risk factors include:
- Tobacco use
- Male sex
- Age greater than 60 years
- Hypertension
- Family history of AAA
- Presence of other large vessel aneurysms
- Non-Hispanic White population
- Peripheral vascular disease
|
| Descending aortic dissection | - Chest and/or upper back pain that radiates to the abdomen
- Approximately one-third of patients with a descending dissection will develop a malperfusion syndrome from the extension throughout the thoracoabdominal aortic branch vessels, causing splenic, kidney, or bowel infarctions
| - Risk factors include:
- Hypertension
- Genetically mediated connective tissue disorders (eg, Marfan syndrome, Ehlers-Danlos syndrome)
- Pre-existing aortic aneurysm, variant of aortic dissection, coarctation
- Bicuspid aortic valve
- Aortic instrumentation or surgery
- Family history of aortic dissection
- Turner syndrome
- Vasculitis (eg, Takayasu, syphilitic)
- Trauma
- Pregnancy and delivery
- Fluroquinolone use
|
| Mesenteric ischemia | - Rapid onset of severe periumbilical pain, often out of proportion to findings on physical examination (ie, lack of tenderness or peritoneal signs)
- Bowel emptying, nausea, and vomiting
- Blood in the stool and elevated serum lactate concentrations may not be present initially
- As bowel ischemia progresses, the abdomen becomes grossly distended with peritoneal signs, a feculent odor to the breath may be appreciated, bowel movements become bloody, and shock develops
| - Risk factors include any conditions that:
- Reduce perfusion to the intestine (eg, low cardiac output)
- Predispose to mesenteric arterial embolism (eg, cardiac arrhythmias, valvular disease)
- Predispose to arterial thrombosis (eg, atherosclerotic disease, abdominal trauma, hypercoagulable state, intra-abdominal malignancy or infection)
- Predispose to venous thrombosis
- Cause vasoconstriction
|
| Hollow viscous perforation and/or peritonitis | - Severe, sudden-onset, diffuse abdominal pain
- Involuntary guarding and/or rebound
- Fever
- Tachycardia, hypotension, signs of shock
| - Risk factors and causes include:
- PUD
- Any process that can result in frank bowel perforation leading to intraperitoneal dissemination of pus and fecal material (eg, acute appendicitis, diverticulitis)
|
| Bowel strangulation and/or intestinal gangrene | - Diffusely distended abdomen
- Involuntary guarding and/or rebound
- Fever
- Tachycardia, hypotension, signs of shock
- Pain that progresses from crampy to constant and severe or localizes in the presence of other symptoms of obstruction is concerning for impending strangulation
| - Can occur with acute bowel obstruction, volvulus, or incarcerated hernia
- Causes of small bowel obstruction include:
- Adhesions (50 to 70%)
- Incarcerated hernias (15%)
- Neoplasms (15%)
- Gallstone ileus (20% of cases among older adult patients)
- Crohn disease can cause fibrotic strictures often leading to repeated episodes of small bowel obstruction
- Risk factors for cecal volvulus include adhesions, recent surgery, congenital bands, and prolonged constipation
- Risk factors for sigmoid volvulus include excessive use of laxatives, sedatives, anticholinergic medications, ganglionic blocking agents, and Parkinsonism medications
|
| Intra-abdominal abscess | - Abdominal or flank pain
- Abdominal tenderness
- Fever
| - Diverticulitis is the most common cause
- Other common sites of abscess formation include liver, kidney, genital tract, and psoas muscle
|
| Biliary sepsis | - Acute cholecystitis – RUQ or epigastric pain that typically occurs 1 hour after fatty food ingestion
- Acute cholangitis (Charcot triad):
- Fever
- Abdominal pain
- Jaundice (frequently absent)
- Severe (suppurative) cholangitis can also include (Reynolds pentad):
- Hypotension (this may be the only sign in older adults or those taking glucocorticoids)
- Mental status changes
| - Complications can include:
- Sepsis (from gangrenous cholecystitis or cholangitis)
- Generalized peritonitis (from free gallbladder perforation into the peritoneum)
- Abdominal wall crepitus (from emphysematous cholecystitis)
- Bowel obstruction ("gallstone ileus" [mechanical obstruction from passage of large gallstone])
|
| Splenic rupture | - LUQ pain and tenderness
- In the rare case of severe hemorrhage, can also cause tachycardia, hypotension, and shock
| - Risk factors and causes include:
- Blunt trauma
- Surgical or endoscopic manipulation (eg, colonoscopy)
- Infectious mononucleosis
|
| Necrotizing pancreatitis | - Constant upper abdominal pain
- Often with band-like radiation to the back
| - Approximately 15 to 25% of patients with acute pancreatitis develop necrosis of the pancreas or peripancreatic tissue
|
| Urinary sepsis (eg, obstructing nephrolithiasis or pyelonephritis) | - A complicated UTI can present with sepsis, multiorgan system dysfunction, shock, and/or acute kidney injury
| - Risk factors include:
- Urinary tract obstruction or abnormalities
- Recent urinary tract instrumentation
- Older age
- Diabetes mellitus
- Nephrolithiasis (a patient with infected urine proximal to an obstructing ureteral stone can quickly become septic if not drained)
|
| Ectopic pregnancy | - Female of childbearing age with the characteristic triad:
- Amenorrhea
- Abdominal/pelvic pain (severe, sudden onset)
- Vaginal bleeding (30% do not have this)
- Hemodynamic instability can develop if the structure (eg, fallopian tube) in which the pregnancy is implanted ruptures and hemorrhages
| - Risk factors include:
- History of pelvic inflammatory disease
- Previous tubal pregnancy
- Endometriosis
- Indwelling intrauterine device
|
| Placental abruption and other pregnancy complications | - An acute placental abruption characteristically presents with:
- Dark vaginal bleeding (the amount of bleeding correlates poorly with the severity of separation)
- Abdominal pain
- Uterine contractions and tenderness
- Acute DIC can develop from a severe abruption (≥50% placental separation) and is life-threatening to both fetus and mother
- Other life-threatening pregnancy-related complications that cause abdominal pain include:
- Necrotic retained products of conception leading to sepsis or toxic shock syndrome
- Complications of pregnancy termination (including unsafe abortion)
- Uterine rupture
| - Risk factors and causes include:
- Maternal hypertension (most common cause)
- Cocaine use
- Alcohol consumption
- Cigarette smoking
- Trauma
- Advanced maternal age
|
| Spontaneous bacterial peritonitis | - Patient with cirrhosis with any of the following:
- Fever or hypothermia
- Abdominal pain
- Altered mental status
- Diarrhea
- Ileus
- Hypotension
| - Usually, there is no apparent source of infection
- SBP occurs in up to one-fourth of patients admitted with cirrhosis and ascites
|
| Fournier gangrene | - Necrotizing fasciitis of the perineum that begins abruptly with severe pain, redness, edema, and induration and spreads rapidly to the anterior abdominal wall and the gluteal muscles
- The scrotum and penis can be involved in males
- The labia can be involved in females
| - Can occur as a result of a breach in the integrity of the gastrointestinal or urethral mucosa
- Risk factors include those for necrotizing soft tissue infection (eg, diabetes, obesity, immunosuppression, malignancy, alcohol misuse)
|
| Toxic megacolon | - Typically presents with at least 1 week of severe, bloody diarrhea followed by acute colonic dilatation
- Often associated with fever, hypotension, confusion, and toxic appearance
| - Causes include:
- Inflammatory bowel disease
- Infectious colitis (eg, Clostridioides difficile, cytomegalovirus colitis)
- Methotrexate therapy
- Malignancy (eg, Kaposi sarcoma)
|
| Toxic shock syndrome | - Characteristic manifestations are fever, rash, hypotension, and multiorgan dysfunction
- Commonly include abdominal pain, nausea, vomiting, and diarrhea
| - Risk factors include:
- Use of high-absorbancy tampons
- Retained tampons
- Wound infections
- Burns
|
| Ruptured hemorrhagic ovarian cyst | - Sudden-onset abdominal or pelvic pain
- Shock is uncommon
- These are rarely life-threatening since most hemorrhagic cysts stop bleeding spontaneously
| - Risk factors include:
- Current, known cyst
- Conditions that predispose to cyst formation (eg, ovulation induction, prior history of ovarian cysts)
- Vaginal intercourse
|
