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4 Rational Diagnostic Procedures 31
check out whether the methods used in the original study can be duplicated in
your environment. Do you have senior radiologists to read the CT at 3 a.m.—or
would the CT be reported only in the morning—after the appendix is, or should
be, in the formalin jar?
Perhaps the day is near when all patients on their way from the ambulance to
the ER will be passed through a total body CT scanner—read by a computer. But,
then luckily we will not be practicing surgery, and this book will be long out of print.
We do not believe, however, that patients will fare better under such a system.
Diagnostic Laparoscopy
Diagnostic laparoscopy is an invasive diagnostic tool (some call it “controlled
penetrating abdominal trauma”) to be used in the operating room after the decision to intervene already has been taken. It has a selective role as discussed in
>
Chap. 57.
Before ending, we wish to cite yet again Leo Gordon: “The emergency room
is the best place to evaluate an emergency.” Think about what investigations you
wish to order while the patient is still in the ER; logistically, in most hospitals, it
will be more difficult to obtain all these tests after the patient has been admitted.
The more the noise—the less the fact.
“God gave you ears, eyes, and hands; use them on the patient in that order.” (William
Kelsey Fry, 1889–1963)
Abdominal Imaging
Moshe Schein · Sai Sajja · Hans Ulrich Elben
“The diagnostic problem of to-day
Has greatly changed—the changes have come to stay;
We all have come to confess, though with a sigh
On complicated tests we much rely
And use too little hand and ear and eye.”
(The Acute Abdomen in Rhyme, Zachary Cope, 1881–1974)
There are fundamental differences in how physicians belonging to the different specialties involved in decision making concerning the “acute abdomen” look
at abdominal imaging. The radiologists’ sharp eyes see “everything,” but they tend
to see “too much” and do not always understand the clinical significance of what
they see. Emergency room (ER) physicians do not see much and do not understand the meaning of the little they do see; all they care about is where to dump the
patient. This leaves us with ourselves, the surgeons. Armed with a better understanding of the natural history of the disease processes and able to correlate radiological imaging with previous operative observations, we should be the finest
interpreters of abdominal imaging. We have already discussed (> Chap. 4) the role
of abdominal imaging in the evaluation of the patient with an acute abdomen. In
this chapter, we will try to provide you with practical tips on how to look at the
images and what to look for.
5
Plain Abdominal X-ray
Moshe Schein
Tragically, the simple, cheap, and safe abdominal X-ray (AXR) is increasingly
bypassed in favor of an immediate computed tomographic (CT) scan, which delivers a much greater radiation dose. This is a pity because there is so much that you
can learn from a quick glance at the AXR.
Moshe Schein
Marshfield Clinic Ladysmith Center, 906 College Avenue, Ladysmith, WI 54848, USA
M. Schein et al. (eds.), Schein’s Common Sense Emergency Abdominal Surger y,
DOI: 10.1007/978-3-540-74821-2_5, © Springer-Verlag Berlin Heidelberg 2010
33
34 Moshe Schein · Sai Sajja · Hans Ulrich Elben
Abnormal Gas Pattern
Gas Outside the Bowel
Free air (pneumoperitoneum) is best seen on an erect chest X-ray but may
also be seen on an AXR (> Fig. 5.1). If the CXR is “normal” and you suspect per-
foration of a viscus, a left lateral decubitus abdominal film may show free gas in
the peritoneal cavity.
Make a habit always to look for atypical gas patterns; occasionally, you may
be rewarded with an eye-popping diagnosis: gas in the biliary tree (pneumobilia)
implies a cholecystoenteric fistula (see gallstone ileus; > Chap. 21), a previous
enterobiliary bypass, or more commonly, a sphincterotomy of the sphincter of Oddi
(via ERCP, endoscopic retrograde cholangiopancreatography) (> Fi g. 5.2). Note that
gas in the intrahepatic biliary ducts is seen centrally, while gas in the periphery of
the liver suggests portal vein gas. The gas finds its way into the portal venous system
through a breach in the bowel wall, usually associated with mesenteric ischemia or
severe colitis and rarely with pyelophlebitis (> Fi g. 5.3). Commonly, gas in the por-
tal vein as a result of ischemic small or large bowel is associated with pneumatosis
intestinalis, that is, the presence of intramural gas (> F ig . 5.4).
Fig. 5.1. Abdominal X-ray, upright position. Pneumoperitoneum. Air under both
diaphragms (arrows)
5 Abdominal Imaging 35
Fig. 5.2. Abdominal X-ray: air in biliary tract (arrow)
Fig. 5.3. Abdominal X-ray: air in portal veins (arrowheads)
36 Moshe Schein · Sai Sajja · Hans Ulrich Elben
Fig. 5.4. Abdominal X-ray: pneumatosis intestinalis (arrow)
Gas in the gallbladder (GB) wall signifies a necrotizing infection (
>
Chap.
20.1). Soap bubble appearance signifies free gas in the retroperitoneum; in the
epigastrium, this is associated with infected pancreatic necrosis (> Chap. 19), in
the right upper quadrant with a retroperitoneal perforation of the duodenum,
and in either gutter with retroperitoneal perforation of the colon (> Fig. 5.5).
Gas Within the Bowel
Abnormal gaseous distension or dilatation of small bowel loops, with or
without fluid levels, implies a small bowel process—be it obstructive (s ma ll bow el
obstruction;
>
Chap. 21), paralytic ileus (> Chap. 48), or inflammatory (Crohn’s
disease, > Chap. 24). Remember: acute gastroenteritis may produce small bowel
fluid levels; the diarrhea hints at the diagnosis.
Abnormal gaseous distention or dilatation of the colon denotes colonic ob-
struction or volvulus (> Chap. 25), colonic inflammation (inflammatory bowel
disease; > Chap. 24), or colonic ileus (pseudo-obstruction; > Chap. 25).
Distinguishing small bowel from colon on an AXR is easy: the “transverse
lines” go all the way across the diameter of the small bowel (the valvulae conniventes)
and only partly across the colon (the haustra). In general, loops of small bowel are
situated centrally, while large bowel occupies the periphery (> F ig . 5.6).
5 Abdominal Imaging 37
a
b
Fig. 5.5. Abdominal X-ray: free retroperitoneal air (arrow)
Fig . 5.6 . Abdomina l X-ray : small bowel versus large bowel. (a) Sma ll bowel obstr uc-
t ion . N ote the va lv u la e con niv en te s (arrow) crossing the whole width of bowel. (b) Volvulus
of the sigmoid colon. Note the haustra crossing a portion of bowel width (arrow)
38 Moshe Schein · Sai Sajja · Hans Ulrich Elben
Useful rules of thumb
Gaseous distension of small bowel + no gas in the colon = complete small
bowel obstruction
Gaseous distension of small bowel + minimal quantity of colonic gas =
partial small bowel obstruction
Significant gaseous distension of both the small bowel and the colon =
paralyticileus
Significant gaseous distension of the colon + minimal distention of the
small bowel = colonic obstruction or pseudo-obstruction
Abnormal Opacities
The opacities you are able to spot on the AXR are the calcified ones: gallstones in the GB (visible in about one-fifth of patients with cholelithiasis), ureteric
stones (visible in some patients with ureteral colic), pancreatic calcifications (seen
in some patients with chronic pancreatitis), and appendicular fecaliths (occasion-
ally seen in patients with appendicitis) (> Fig . 5.7). Clinically irrelevant calcified
Fig. 5.7. Abdominal X-ray: appendicular fecalith (arrows; when visualized in a pa-
tient with symptoms and signs of acute appendicitis, it is highly diagnostic)
5 Abdominal Imaging 39
lesions that are common include phleboliths in the pelvis and calcified lymph
nodes in the right iliac fossa, usually associated with previous tuberculosis. Fecal
matter may opacify the rectum and colon to a variable degree—achieving extreme
proportions in patients with fecal impaction. Note that a moderate amount of fecal
material in the right colon is normal, while a column of feces on the left implies
some abnormality, ranging in severity from simple constipation to early malignant obstruction. Another opacity, which may surprise you, is a forgotten surgical
>
instrument or gauze swab (
Fig. 5.8).
Also, massive ascites has a typical picture on AXR (> Fig. 5.9).
The simple abdominal X-ray is an extension of your clinical evaluation and
is not complete without it.
Fig. 5.8. Abdominal X-ray: retained surgical clamp
40 Moshe Schein · Sai Sajja · Hans Ulrich Elben
Fig. 5.9. Abdominal X-ray: massive ascites. In the supine position, the bowel gas
lies centrally, and there is nothing peripherally. The lighter bowel loops are practically
floating on a lake of ascites in the abdominal cavity
Computed Tomography in Abdominal Emergencies
Sai Sajja and Moshe Schein
The road to the operating room does not always have to pass through the CT
scanner but an appropriately indicated CT may obviate the need for a surgical route.
The supremacy of CT in the imaging of the abdomen is not in dispute. CT
shows details that no other diagnostic method does: free gas, fluid, masses, tissue
planes, inflammatory changes, opacities, blood vessels, and organ perfusion. So,
why should we object to the indiscriminate use of CT as practiced today in many
countries around the world?
We object for the simple reason that in most patients the diagnosis can be established without CT—the obtaining of which often only delays treatment and confuses
the picture by showing nonsignificant findings (see > Chap. 4). Typically, whenever
5 Abdominal Imaging 41
radiologists publish papers on the use of CT in various abdominal emergencies, they
declare sensitivity and specificity rates approaching 100%. When surgeons, however,
look objectively at the overall impact of CT on the diagnosis and treatment of specific
conditions, the real impact of CT is often marginal (e.g., acute appendicitis).
In addition, remember that the radiation exposure of one abdominal CT examination can be several hundred times that of a CXR. According to the U.S. Food
and Drug Administration, this amount of radiation exposure may be associated
with a small increase in radiation-associated cancer in an individual. This is particularly relevant if people were to receive this examination repeatedly, starting at
a young age—as in the young lady presenting with lower abdominal pain to an ER
in Brooklyn, where CT showed an ovarian cyst. Two weeks later, she arrives up at
another ER in the Bronx, where another CT documents (surprise!) the same cyst.
The key word in the effective use of abdominal CT is “selectivity.” Rather
than indicating a need for exploration, CT is more useful in deciding when not to
operate—avoiding unnecessary “exploratory” laparotomies or “diagnostic”
laparoscopies. Also, a “normal CT” can exclude surgical abdominal conditions,
allowing the early discharge of patients without the need for admission for
observation.
The recent introduction of fast scanners that image the abdomen from the
diaphragm to the pubis in a single breath has greatly improved the image quality
and reduced the time required to obtain the images. However, it does require that
patients be transported to the CT suite and exposes them to the risks of aspiration
of oral contrast media and adverse reactions to intravenous contrast media such as
anaphylaxis and nephrotoxicity. Unenhanced (no intravenous contrast) helical or
spiral CT scans are being increasingly used in suspected appendicitis, while CTs
without oral contrast have been reported as accurate in patients suffering from
blunt abdominal trauma. Whatever the CT methodology in your hospital, you—
who know the abdomen inside out and understand the natural history of abdominal diseases—have to be able to analyze the CT images better than the radiologist.
As is the case with all imaging studies, interpretation of CT scan images requires a systematic approach, and it takes plenty of practice to become confident
in one’s ability. One also needs to spend time, and the more time you spend the
more findings—both negative and positive—you pick up. We describe the way we
look at a CT scan of the abdomen; it is not “ideal” or “perfect,” but it works for us,
especially in the middle of the night when all the radiologists are snoring in bed.
(In the morning they will, with latte in hand, dictate detailed reports.)
It is important to pay attention to a few technical aspects of the study before
beginning to interpret it. While there is a lot of literature to support the notion
that there is no need for oral or intravenous contrast material, the use of the latter
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