DOI:10.2214/AJR.07.3837
AJR 2008; 191:1093-1099
© American Roentgen Ray Society
Gasless Abdomen in the Adult: What Does It Mean?
William M. Thompson1
1 Department of Radiology, Duke University Medical Center, Box 3808, Durham, NC
27710.
Received February 14, 2008;
accepted after revision April 11, 2008.
Address correspondence to W. M. Thompson
(thomp132{at}mc.duke.edu).
CME
This article is available for CME credit.
See
www.arrs.org
for more information.
Abstract
OBJECTIVE. The objective of this article is to illustrate the causes
of a gasless abdomen in an adult.
CONCLUSION. The gasless abdomen in the adult is often interpreted as
nonspecific, which does not provide useful information for the patient's
physician. There are at least six causes of the gasless abdomen in the adult.
A specific cause of the gasless abdomen can usually be made when the patient's
history is known. The most serious cause of the gasless abdomen is small-bowel
obstruction with or without ischemia.
Keywords: abdominal radiography • gasless abdomen adult • small-bowel obstruction
Introduction
A gasless abdomen seen on an abdominal radiograph is a common entity in the
neonate that may be caused by many serious gastrointestinal tract
abnormalities [1]. The gasless
abdomen on abdominal radiographs in the adult has received little attention in
the literature [2,
3]. When a gasless abdomen is
encountered, the radiologist will describe the finding and conclude
"nonspecific abdomen." This does not provide useful information to
the patient's physician.
In my experience, a number of entities can produce a gasless abdomen in the
adult. These range from benign to life-threatening. In some patients the
radiologist can determine the precise cause from the radiographs, but in many
other cases the patient's history is necessary to determine the specific cause
of the gasless abdomen. This is particularly true in patients who have a
small-bowel obstruction producing a gasless abdomen. After reading this
article, radiologists should be able to appropriately interpret abdominal
radiographs in the adult that show a paucity of intestinal gas.
Normal Abdomen
Most normal adults have scattered gas throughout their small and large
bowel [4,
5]. In the large bowel there is
usually mottled gas due to the presence of feces mixed with gas. This
increases with age. There are usually numerous loops of gas-containing small
bowel centrally located in the abdomen. The healthy patient with little or no
small-bowel gas probably swallows very little air, especially during meals.
The clue to identifying these patients is that they lack clinical signs of
small-bowel obstruction or ischemia (Figs.
1A,
1B and
2).
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Fig. 1A —38-year-old man with 2 days of mild abdominal pain and no
symptoms of bowel obstruction. Note paucity of small-bowel gas on supine
(A) and upright (B) abdominal radiographs. Also note small
amount of gas in right colon (arrows).
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Fig. 1B —38-year-old man with 2 days of mild abdominal pain and no
symptoms of bowel obstruction. Note paucity of small-bowel gas on supine
(A) and upright (B) abdominal radiographs. Also note small
amount of gas in right colon (arrows).
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Small-Bowel Obstruction and Ischemia
The cause of the gasless abdomen in small-bowel obstruction is the presence
of fluid rather than air filling the lumen of the dilated small bowel proximal
to the site of obstruction (Figs.
3A,
3B and
4A,
4B). Ischemia can produce
similar findings even though thickening of the bowel wall may be present
[2,
3] (Fig.
5A,
5B,
5C). A proximal small-bowel
obstruction may produce a gasless abdomen (Fig.
6A,
6B,
6C).
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Fig. 3A —17-year-old boy with testicular sarcoma after orchiectomy and
retroperitoneal lymph node resection who developed signs and symptoms of
small-bowel obstruction. Digital radiograph shows nasoenteric feeding tube in
place and small amount of barium present in right colon (arrow) and
rectum from prior study. Note lack of gas in small bowel.
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Fig. 3B —17-year-old boy with testicular sarcoma after orchiectomy and
retroperitoneal lymph node resection who developed signs and symptoms of
small-bowel obstruction. Axial CT image through lower abdomen shows dilated
small bowel completely filled with fluid (arrow). High-grade
small-bowel obstruction due to dense adhesions was found at surgery.
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Fig. 4A —73-year-old woman with history of lymphoma who presented with
nausea, vomiting, and sharp pain in left lower abdomen. Supine abdominal
radiograph shows paucity of small-bowel gas (large arrow) and small
amount of gas and feces in right colon (small arrows).
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Fig. 4B —73-year-old woman with history of lymphoma who presented with
nausea, vomiting, and sharp pain in left lower abdomen. Coronal CT scan shows
multiple fluid-filled loops of small bowel extending to pelvis, where
transition point was identified (not shown) just distal to feces
(arrow) in small bowel ("small-bowel feces sign").
Adhesion found at surgery was responsible for obstruction.
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Fig. 5A —72-year-old woman with severe abdominal pain and vomiting.
Supine abdominal radiograph shows paucity of gas in right side of abdomen with
air-containing jejunum that has fold thickening (arrow).
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Fig. 5B —72-year-old woman with severe abdominal pain and vomiting.
Axial CT scan through mid abdomen shows minimal thickening of air- and
fluid-containing dilated small bowel on left side of abdomen
(arrows). Note fluid density in central mesentery and tiny amount of
ascites in left lower lateral abdomen (arrowhead).
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Fig. 5C —72-year-old woman with severe abdominal pain and vomiting.
Axial CT scan at level of iliac crests shows dilated fluid-filled small bowel,
increased density in central mesentery, and engorged vessels (arrow).
At surgery, small-bowel obstruction and ischemic small bowel caused by
adhesions were found.
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Fig. 6B —40-year-old woman with gradual onset of upper abdominal pain.
Upright abdominal radiograph shows normal colonic gas and distended loop of
proximal small bowel (arrow) just inferior to stomach and transverse
colon.
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Fig. 6C —40-year-old woman with gradual onset of upper abdominal pain.
Radiograph from enteroclysis (tube had been removed) shows abrupt change in
caliber of proximal small bowel (arrow) and marked dilation of
obstructed proximal small bowel. Distal small bowel is normal. Tiny (1 cm)
ulceration at site of obstruction was noted on other radiographs. At surgery,
less-than-totally-obstructing 1-cm primary jejunal adenocarcinoma was
resected.
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Small-bowel obstruction with or without ischemia is the most serious cause
of the gasless abdomen in the adult because it may be life-threatening. The
gasless abdomen in the presence of a clinical finding of bowel obstruction
implies a more long-standing obstruction, often in the presence of a
closed-loop obstruction, strangulation, or ischemic small bowel. Therefore, it
is imperative that the radiologist know the patient's history and laboratory
data. If symptoms and signs of obstruction or ischemia are present with a
gasless abdomen on abdominal radiographs, the referring physician should be
contacted immediately. The patient should undergo either emergent confirmatory
CT (Figs. 3A,
3B and
4A,
4B) or a surgical consultation.
Some patients will have upright or decubitus radiographs in addition to their
nondependent radiographs. These may help confirm the diagnosis of small-bowel
obstruction by showing significant air–fluid levels or the
string-of-pearls sign (Fig.
7A,
7B).
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Fig. 7A —50-year-old man with abdominal pain, nausea, and vomiting.
Supine abdominal radiograph shows paucity of gas in lower abdomen and several
faintly gas-filled bowel loops in left upper quadrant, some of which are left
colon; others could represent dilated fluid-filled small bowel
(arrow).
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Fig. 7B —50-year-old man with abdominal pain, nausea, and vomiting.
Upright abdominal radiograph shows scattered colonic air–fluid levels in
periphery of abdomen. Note multiple tiny air–fluid levels in central
abdomen that are in small bowel (arrows) and represent dilated
fluid-filled loops of small bowel with tiny amounts of gas, the
string-of-pearls sign. At surgery, distal small-bowel obstruction caused by
adhesion was found.
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CT is the most valuable imaging technique in the evaluation of the gasless
abdomen. It can be of great value by confirming not only the presence of a
small-bowel obstruction but also the site and cause of the obstruction, as
well as showing complications such as closed-loop obstruction and signs of
ischemic small bowel (Fig. 5A,
5B,
5C). This information is
critical for the surgeon to manage the patient promptly.
At my institution, we avoid the term "nonspecific abdomen" when
a gasless abdomen is encountered. We make every effort to correlate the
abdominal radiographic findings with the patient's history so the examination
can be interpreted as normal or abnormal.
Ascites
Ascites may be the most common cause of the gasless abdomen in the adult.
One can usually determine that ascites is present by noting the classic
findings: obliteration of the fat outlining the internal edge of the liver,
increased distance between the flank stripe and both the ascending and
descending colon, medial displacement of the lateral liver edge, central
location of small-bowel loops that may be displaced, bulging flanks, increased
density over the entire abdomen, and fluid accumulation in the pelvis, the
"dogears sign"
[5–7]
(Figs. 8A,
8B and
9). A history of metastatic
disease, especially ovarian carcinoma, or portal hypertension is helpful in
confirming the presence of ascites.
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Fig. 8A —73-year-old man with hepatic and renal failure due to amyloid
and increasing abdominal distention. Supine abdominal radiograph shows
gas-filled stomach and many classic findings of ascites, increased density
over abdomen, central location of a few loops of contrast-filled small bowel
(arrow), and loss of normal fat outlining posterior liver edge as
well as loss of all other normal fat planes.
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Fig. 8B —73-year-old man with hepatic and renal failure due to amyloid
and increasing abdominal distention. Coronal CT image through mid abdomen
shows central displacement of small bowel and medial displacement of liver due
to ascites.
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Fig. 9 —71-year-old woman with known ascites due to liver failure.
Supine radiograph of lower abdomen shows perivesical fat (arrows)
outlining dome of bladder below and ascites above that extend into perivesical
recesses. This finding due to visualization of fluid above perivesical fat has
been called "dogears sign."
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Surgery, Especially Total Colectomy
For reasons that are unclear, many patients, after a total colectomy, have
a paucity of gas in the small bowel (Fig.
10A,
10B). Without surgical clips,
it can be difficult to recognize the patient has had surgery such as a total
colectomy (Fig. 10A,
10B). One clue is these are
usually younger patients who have had a colectomy for adenomatous polyposis or
diffuse colitis. Other postsurgical patient groups we have encountered with a
gasless abdomen include those who have under gone esophagogastrectomy,
gastrectomy, and low anterior resection for colorectal adenocarcinoma (Fig.
11A,
11B).
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Fig. 10A —48-year-old woman 6 months after total colectomy for
ulcerative colitis who presented for ileostomy removal. Preliminary abdominal
radiograph shows paucity of gas throughout abdomen. Note surgical staples in
pelvis from J-pouch (arrow).
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Fig. 10B —48-year-old woman 6 months after total colectomy for
ulcerative colitis who presented for ileostomy removal. Radiograph after
instillation of contrast material into J-pouch shows normal distal ileum and
contrast material filling ileostomy bag. No extravasation of contrast medium
or stricture at ileoanal anastomosis was seen.
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Fig. 11A —55-year-old man 2 days after esophagogastrectomy for
high-grade Barrett's esophagus. Supine abdominal radiograph before barium
swallow shows paucity of bowel gas, jejunostomy feeding tube, and cardiac
monitoring wires.
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Fig. 11B —55-year-old man 2 days after esophagogastrectomy for
high-grade Barrett's esophagus. Radiograph from barium swallow shows normal
postoperative esophagogastrectomy. Note paucity of distal bowel gas.
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Gastroenteritis
Patients with gastroenteritis have a paucity of intestinal gas during their
acute illness due to vomiting or diarrhea
(Fig. 12). Patients with acute
pancreatitis, graft-versus-host disease, inflammatory bowel disease, and
irritable bowel syndrome can also have significant diarrhea that may produce a
gasless abdomen [8,
9] (Fig.
13A,
13B,
13C,
13D,
13E). By knowing the patient's
history and symptoms, one can explain the gasless abdomen seen on abdominal
radiographs.
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Fig. 13A —28-year-old man with known acute myelogenous leukemia who
presented with nausea, diarrhea, and fever. Supine abdominal radiograph shows
paucity of gas throughout entire abdomen. Tiny amount of gas is present in
sigmoid colon (arrow).
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Fig. 13B —28-year-old man with known acute myelogenous leukemia who
presented with nausea, diarrhea, and fever. Axial CT images through abdomen
show both small- and large-bowel wall thickening (arrows). Small
amount of ascites is present in sigmoid mesentery and pelvis
(arrowheads, B and C). Note moderate dilation of
duodenum and proximal jejunum (arrowhead) due to inflammation in
proximal small-bowel mesentery (not shown). After treatment, all findings were
shown to have resolved on 2-week follow-up CT. Findings were thought to be
caused by neutropenic enterocolitis.
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Fig. 13C —28-year-old man with known acute myelogenous leukemia who
presented with nausea, diarrhea, and fever. Axial CT images through abdomen
show both small- and large-bowel wall thickening (arrows). Small
amount of ascites is present in sigmoid mesentery and pelvis
(arrowheads, B and C). Note moderate dilation of
duodenum and proximal jejunum (arrowhead) due to inflammation in
proximal small-bowel mesentery (not shown). After treatment, all findings were
shown to have resolved on 2-week follow-up CT. Findings were thought to be
caused by neutropenic enterocolitis.
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Fig. 13D —28-year-old man with known acute myelogenous leukemia who
presented with nausea, diarrhea, and fever. Axial CT images through abdomen
show both small- and large-bowel wall thickening (arrows). Small
amount of ascites is present in sigmoid mesentery and pelvis
(arrowheads, B and C). Note moderate dilation of
duodenum and proximal jejunum (arrowhead) due to inflammation in
proximal small-bowel mesentery (not shown). After treatment, all findings were
shown to have resolved on 2-week follow-up CT. Findings were thought to be
caused by neutropenic enterocolitis.
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Fig. 13E —28-year-old man with known acute myelogenous leukemia who
presented with nausea, diarrhea, and fever. Axial CT images through abdomen
show both small- and large-bowel wall thickening (arrows). Small
amount of ascites is present in sigmoid mesentery and pelvis
(arrowheads, B and C). Note moderate dilation of
duodenum and proximal jejunum (arrowhead) due to inflammation in
proximal small-bowel mesentery (not shown). After treatment, all findings were
shown to have resolved on 2-week follow-up CT. Findings were thought to be
caused by neutropenic enterocolitis.
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Large Abdominal Mass
Patients with a large abdominal mass rarely present a problem to the
radiologist interpreting abdominal radiographs. Huge masses are usually
readily apparent on the radio graphs (Fig.
14A,
14B). Hepatomegaly,
splenomegaly, retroperitoneal malignancies, mesenteric cysts, and benign and
malignant gynecologic tumors are the most common large masses that produce a
gasless abdomen in adults.
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Fig. 14A —54-year-old woman with marked abdominal distention. Supine
abdominal radiograph shows marked abdominal fullness, displacement of small
bowel cephalad (arrow), and elevation of hemidiaphragm.
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Fig. 14B —54-year-old woman with marked abdominal distention. Axial CT
scan through mid abdomen shows large multiseptate fluid-filled mass that
proved to be metastatic sigmoid colon adenocarcinoma to left ovary.
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Acknowledgments
I thank Eric Paulson for his editorial assistance.
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Abstract
Introduction
