The “Acute Abdomen”
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| CAUSES OF ACUTE ABDOMEN |
An acute abdominal condition should be described as acute abdomen when a patient complains of abdominal pain that persists for more than a few hours and is associated with tenderness or other evidence of an inflammatory reaction or a visceral dysfunction. The diagnosis of the cause of acute abdominal conditions remains one of the most challenging problems in medicine. Many pathologic processes, both intraabdominal and extra-abdominal, may result in an acute abdomen. An accurate history, thorough physical examination, and proper laboratory examinations help to make the broad differential diagnosis of causes.
Pain
in the right upper quadrant may originate from cardiac, pulmonary,
gastrointestinal, and renal conditions. Evidence of cardiac failure may
implicate the heart; a pleuritic type of pain, cough, sputum, and auscultatory
findings over the right lower lobe point may implicate disease above the
diaphragm. A prodromal period of nausea and anorexia, followed by pain, jaundice,
and enlargement of the liver, suggests hepatitis, which must be differentiated
from acute cholecystitis, which presents with colicky pain and a tender,
globular mass in the right upper quadrant. Urinalysis showing red and/or white
blood cells will suggest pyelonephritis or renal stone, whereas glycosuria and
ketonuria may be the first positive evidence that the pain is a clinical facet
of diabetic acidosis. Unquestionably, the most difficult area in which to make
a diagnosis is the right lower quadrant in females. Though persistent pain in
this region should be considered a sign of appendicitis until proved otherwise,
one must keep in mind that a twisted, ruptured, or bleeding ovarian cyst, a
pelvic inflammatory process, or a twisted pedunculated fibroid may cause
identical symptoms. The situation is simplified only by the fact that surgery
is indicated for all these lesions, provided that
systemic and renal diseases have been excluded. With pain and tenderness on the
left side, a tumor or diverticulitis must enter into the differential
diagnosis. Intestinal obstruction, whatever its cause, may start its clinical appearance
with the signs and symptoms of acute abdomen. A patient with an abdominal scar
from previous surgery, who complains of cramps and vomiting, must be assumed to
have intestinal obstruction until proved otherwise.
Although
the location of pain usually fixes the site of a disease process, pain may be
felt at a distance from the pathologic process. During a careful physical
examination in which one is looking closely for the maximal area of tenderness,
guarding or rebound may accurately disclose the site of disease; the imprecise
nature of nociception localizing in all viscera can be humbling to even the
best clinician. Appendicitis frequently begins with epi- gastric or
periumbilical pain before localizing to the right lower quadrant, a site often
referred to as the McBurney point. Although acute cholecystitis is most
commonly identified in the right upper quadrant and will result in a positive
Murphy sign, it commonly presents with epigastric pain or pain in other
quadrants, the periumbilical area, or the right shoulder. Similarly, perforated
peptic ulcer and pancreatitis may manifest themselves with lower abdominal
pain, particularly if there has been extravasation of inflammatory exudate down
the pericolonic gutters. Rebound tenderness, the most significant if not truly
pathognomonic sign of peritoneal inflammation, is almost always an indication
of the need for surgical intervention. The exception to this rule is a
peritoneal reaction that can be shown to be due to a systemic disease (e.g.,
systemic lupus erythematosus or sickle cell crisis).
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| ACQUIRED CAUSES OF OBSTRUCTION |
With
any doubt about the abdominal diagnosis, upright and supine views of the
abdomen and an upright chest roentgenogram should be obtained immediately. The
latter will exclude or ascertain the presence of pneumonia, pulmonary
infarction, congestive heart failure, pericardial effusion, or fractured ribs,
all of which can present with the clinical picture of an acute abdomen. On the
abdominal or chest film, free air under the diaphragm usually indicates a
perforated viscus and, thus, the need for urgent surgical intervention. Opaque
calculi may be visible and lead to a diagnosis of cholecystitis, chronic pancreatitis,
renal lithiasis, or even gallstone ileus. In cases of injury manifesting
paralytic ileus, roentgen examination may disclose fracture of a vertebra or
the pelvis. Localized ileus (the sentinel loop) may be seen in
pancreatitis, appendicitis, or mesenteric infarction. Volvulus of the sigmoid
or cecum presents with a characteristic appearance on
x-ray. In most cases, emergency computerized tomography (CT) scanning of the
abdomen and pelvis will reveal the diagnosis. Until perforation has been
definitively ruled out, liquid-soluble contrast should be used rather than
ingestion of barium.
Examining
the abdominal fluid at the time of laparoscopy or in an emergency setting with
a peritoneal tap performed with a fine needle may yield considerable
information. Clear fluid is obtained in the presence of an early peritoneal
response to an inflammatory process. The process has progressed if leukocytes
and bacteria are found in a turbid fluid. Sanguineous fluid with a positive
amylase reaction points to acute hemorrhagic pancreatitis, whereas a frankly
bloody fluid must be attributed to trauma, a ruptured spleen or liver, mesenteric
vascular occlusion, a ruptured or twisted and infarcted
ovarian cyst, or ectopic pregnancy.
