|
A 61-year-old man with a history of
hypertension, diabetes, peripheral vascular disease, and
congestive heart failure presents to the Emergency
Department with left lower-extremity pain at rest and with
a nonhealing ulcer of the left foot. The patient is
admitted to the hospital for treatment of the ulcer and for
a workup of his peripheral vascular disease.
Plain radiographs of the patient’s left foot and left
lower leg show evidence of osteomyelitis of the distal
first phalanx and distal tibia. After general and vascular
surgeons evaluate him, they decide to proceed with a
below-the-knee amputation on the left side. On
postoperative day 2, the patient reports having severe
midepigastric abdominal pain, as well as nausea, vomiting,
and diarrhea, with no hematemesis or hematochezia.
On physical examination, the patient is afebrile but
hypotensive, with a blood pressure of 88/54 mm Hg. He has
slight tachycardia at a rate of 120 bpm. His oxygen
saturation while breathing room air is 90%. His abdomen is
distended, with diffuse rebound tenderness. Hypoactive
bowel sounds are auscultated. The rest of his physical
findings, including the condition of his postoperative
wounds, are unremarkable. Laboratory results, including CBC
and electrolyte levels, are within normal limits.
Plain radiographs of the abdomen are obtained (see Image
1), followed by contrast-enhanced CT scans of the abdomen
and pelvis (see Images 2-3).
What is the diagnosis?
Answer
Portal venous air with
pneumatosis intestinalis: The plain radiograph of the
abdomen shows mildly dilated loops of small bowel and a
bubbly appearance on the left side, which suggests air in
the bowel wall, also known as pneumatosis (see Image 1,
arrowheads). Contrast material in the urinary tract is from
a recent angiographic study that was performed to evaluate
the patient for peripheral vascular disease. The right
upper quadrant contains several branching and linear lucent
areas overlying or in the liver; these likely represent
biliary or portal venous air (arrows). Subsequent CT scans
confirm these findings, showing air in the superior
mesenteric vein and intrahepatic ramifications of the
portal vein (see Images 2-3). Circumferential pneumatosis
is seen in the proximal aspect of the small bowel.
Differentiating biliary air from portal venous air is
critical because biliary air is usually benign but portal
venous air is commonly a harbinger of a grave outcome.
Because bile flows centrally to the common bile duct,
biliary air lies centrally in the liver. Biliary air is
characteristically found more than 2 cm from the hepatic
capsule. By comparison, because portal blood flows
peripherally, portal venous air should at least partially
lie within 2 cm of the hepatic capsule. The pattern of
distribution is often equivocal, and further imaging with
CT is necessary to differentiate the 2 conditions. In the
optimal case, the air can be traced back and localized to
the biliary tree or portal venous system on CT scans.
Portal venous air is not a disease in itself but, rather,
is a result of various causes, some harmless and others
not. The most worrisome and most common underlying cause is
bowel ischemia (with or without infarction). Bowel ischemia
and infarction likely cause the mucosal barrier to break
down, allowing air and toxins to leak into the portal
venous system. Portal venous air is sometimes seen after a
barium enema study or colonoscopy and in association with
bowel obstruction, necrotizing enterocolitis in children,
diverticulitis, intra-abdominal abscesses, or toxic
megacolon.
Pneumatosis intestinalis is characterized by the presence
of extraluminal gas in the submucosal and/or subserosal
layers of the bowel wall. It is considered an ominous
finding in patients with ischemia, particularly if it is
associated with portomesenteric gas. Pneumatosis
intestinalis is also seen in other conditions or
situations, such as chronic obstructive pulmonary disease,
connective tissue disorders, infectious enteritis, celiac
disease, leukemia, organ transplantation, amyloidosis,
steroid treatment, chemotherapy, and AIDS.
Pneumatosis intestinalis occurs in 2 forms: primary and
secondary. Primary pneumatosis intestinalis, which occurs
in 15% of patients, is a benign idiopathic condition in
which several thin-walled cysts form in the submucosa or
subserosa of the intestinal wall. This type is usually not
associated with symptoms, and it may be found incidentally
during radiography or endoscopy. This primary form is often
called pneumatosis cystoides intestinalis. The secondary
form, which occurs in 85% of patients, is associated with
obstructive pulmonary disease, as well as obstructive and
necrotic GI diseases.
For more information, see the eMedicine articles Mesenteric
Ischemia and Pneumatosis
Intestinalis.
References
- Alobaidi M,, Jafri SZ: Mesenteric Ischemia. eMedicine
Journal [serial online]. 2003. Available at: www.emedicine.com/radio/topic446.htm
Accessed: September 19, 2006.
- Goyal SK,, Weltman DI: Pneumatosis Intestinalis. eMedicine
Journal [serial online]. 2005. Available at: www.emedicine.com/radio/topic560.htm.
Accessed September 19, 2006.
- Kernagis LY, Levine MS, Jacobs JE: Pneumatosis
intestinalis in patients with ischemia: correlation of
CT findings with viability of the bowel. AJR Am J
Roentgenol 2003; 180: 733-6. [MEDLINE 12591685]
- Sebastia C, Quiroga S, Espin E, et al: Portomesenteric
vein gas: pathological mechanisms, CT findings, and
prognosis. Radiographics 2000; 20: 1213-24.
[MEDLINE 10992012]
- Wiesner W, Mortele KJ, Glickman JN, et al: Pneumatosis
intestinalis and portomesenteric venous gas in
intestinal ischemia: Correlation of CT findings with
severity of ischemia and clinical outcome. AJR Am J
Roentgenol 2001;177: 1319-23. [MEDLINE 11717075]
Authors:
Charlie Clarke, MD
Radiology Resident
UT Southwestern Medical Center,
Dallas, TX
Pramod Gupta, MD
Staff Radiologist
Dallas VA Medical Center,
Clinical Assistant Professor
University of Texas Southwestern,
Dallas, TX
eMedicine Editors:
Erik D. Schraga, MD,
Department of Emergency Medicine,
Kaiser Permanente,
Santa Clara Medical Center, Calif
Rick G. Kulkarni, MD
Assistant Professor,
Yale School of Medicine,
Section of Emergency Medicine,
Department of Surgery,
Attending Physician,
Medical Director,
Department of Emergency Services,
Yale-New Haven Hospital, Conn
|
Link
to further Information on:
|
|