Acute Abdomen

Acute, Catastrophic Abdominal Pain

Intense abdominal pain of acute onset or pain associated with syncope,hypotension,

or toxic appearance necessitates rapid yet orderly evaluation. Consider

obstruction,perforation, or rupture of hollow viscus; dissection or rupture of

major blood vessels (esp. aortic aneurysm); ulceration; abdominal sepsis; ketoacidosis; and adrenal crisis.

Brief History and Physical Examination Historic features of importance

include age; time of onset of the pain; activity of the pt when the pain began;

location and character of the pain; radiation to other sites; presence of nausea,

vomiting,or anorexia; temporal changes; changes in bowel habits; and menstrual

history. Physical exam should focus on the pt’s overall appearance [writhing

in pain (ureteral lithiasis) vs. still (peritonitis,perforation)], position (a pt leaning forward may have pancreatitis or gastric perforation into the lesser sac),

presence of fever or hypothermia, hyperventilation,cyanosis,bowel sounds,

direct or rebound abdominal tenderness,pulsating abdominal mass, abdominal

bruits,ascites, rectal blood,rectal or pelvic tenderness, and evidence of coagulopathy.

Useful laboratory studies include hematocrit (may be normal with

acute hemorrhage or misleadingly high with dehydration),WBC with differential

count,arterial blood gases, serum electrolytes, BUN, creatinine, glucose,

lipase or amylase,and UA. Females of reproductive age should have a pregnancy

test. Radiologic studies should include supine and upright abdominal

films (left lateral decubitus view if upright unobtainable) to evaluate bowel

caliber and presence of free peritoneal air,cross-table lateral film to assess aortic

diameter; CT (when available) to detect evidence of bowel perforation,inflammation, solid organ infarction, retroperitoneal bleeding, abscess, or tumor. Abdominal paracentesis (or peritoneal lavage in cases of trauma) can detect evidence of bleeding or peritonitis. Abdominal ultrasound (when available) reveals evidence of abscess,cholecystitis, biliary or ureteral obstruction, or hematoma and is used to determine aortic diameter.

Diagnostic Strategies The initial decision point is based on whether the

pt is hemodynamically stable. If not,one must suspect a vascular catastrophe

such as a leaking abdominal aortic aneurysm. Such pts receive limited resuscitation

and move immediately to surgical exploration. If the pt is hemodynamically

stable,the next decision point is whether the abdomen is rigid. Rigid

abdomens are most often due to perforation or obstruction. The diagnosis can

generally be made by a chest and plain abdominal radiograph.

If the abdomen is not rigid,the causes may be grouped based on whether

the pain is poorly localized or well localized. In the presence of poorly localized

pain,one should assess whether an aortic aneurysm is possible. If so, a CT scan

can make the diagnosis; if not,early appendicitis, early obstruction, mesenteric

ischemia,inflammatory bowel disease, pancreatitis, and metabolic problems are

all in the differential diagnosis.

Pain localized to the epigastrium may be of cardiac origin,esophageal inflammation or perforation,gastritis,peptic ulcer disease, biliary colic or cholecystitis, and pancreatitis. Pain localized to the right upper quadrant includes

those same entities plus pyelonephritis or nephrolithiasis,hepatic abscess, subdiaphragmatic absess,pulmonary embolus,or pneumonia or be of musculoskeletal origin. Additional considerations with left upper quadrant localization are infarcted or ruptured spleen,splenomegaly, and gastric or peptic ulcer.

Right lower quadrant pain may be from appendicitis,Meckel’s diverticulum, Crohn’s disease, diverticulitis,mesenteric adenitis,rectus sheath hematoma, psoas abscess, ovarian abscess or torsion, ectopic pregnancy,salpingitis,familial fever

syndromes,uterolithiasis,herpes zoster. Left lower quadrant pain may be due

to diverticulitis,perforated neoplasm, and other entities previously mentioned.

TREATMENT

Intravenous fluids,correction of life-threatening acid-base disturbances, and

assessment of need for emergent surgery are the first priority; careful followup

with frequent reexamination (when possible,by the same examiner) is

essential. The use of narcotic analgesia is controversial. Traditionally,narcotic

analgesics were withheld pending establishment of diagnosis and therapeutic

plan,since masking of diagnostic signs may delay needed intervention. However,

evidence that narcotics actually mask a diagnosis is sparse.