AJR 2001; 177:95-98
© American Roentgen Ray Society
CT of Cecal Volvulus
Unraveling the Image
Carolyn J. Moore1,
Frank M. Corl1 and
Elliot K. Fishman1,2
1
Russell H. Morgan Department of Radiology and Radiological Science, Johns
Hopkins University School of Medicine, Baltimore, MD 21287.
2
Department of Radiology, Johns Hopkins Hospital, 601 N. Caroline St.,
Baltimore, MD 21287.
Received October 20, 2000;
accepted after revision January 9, 2001.
Address correspondence to E. K. Fishman.
Introduction
Volvulus of the cecum is a torsion of the bowel around its own mesentery
that often results in a closed-loop obstruction. Cecal volvulus can only occur
in the small percentage (11-25%) of the population who have a developmental
failure of peritoneal fixation, allowing the proximal colon to be free and
mobile [1]. The second
requirement is restriction of the bowel at a fixed point within the abdomen
that serves as a fulcrum for rotation, such as an adhesion, abdominal mass, or
scarring from calcified lymph nodes
[2].
Recognition of the CT signs of cecal volvulus is critical because the
findings at clinical examination are often vague and because CT is usually the
imaging technique of choice for patients presenting with acute abdominal pain
[3]. Furthermore, diagnosis may
be difficult: The images on the patient's abdominal radiographs could be
obscured if the closed loop is filled with fluid, oriented in an
anteroposterior plane, or overlain by loops of air-distended bowel
[4]. CT reveals the presence
and location of the volvulus and gives the added benefit of allowing early
identification of potentially fatal complications, such as ischemia and
perforation. Three-dimensional (3D) reconstructions may further improve
diagnostic capabilities by allowing visualization of the entire bowel in a
single image. This pictorial essay uses schematic diagrams and cases of
representative patients to describe the CT appearance of cecal volvulus and
the diagnostic benefit of 3D imaging.
Technique
This report is based on data collected from five patients with cecal
volvulus that had been confirmed either by surgery or colonoscopic
decompression. The CT technique varied because the images were obtained from
several different scanners. We currently scan the abdomen and pelvis after the
IV administration of 100-120 mL of iodinated contrast medium injected at a
rate of 2-3 mL/sec. Scanning is performed on a Somatom Plus 4 or Volume Zoom
scanner (Siemens, Forchheim, Germany). We scan either with 5-mm collimation,
5-mm scan increments, and a table speed of 8-10 mm/sec or with 3-mm
collimation, 5-mm scan increments, and a table speed of 15 mm/sec.
Clinical Background
Cecal volvulus accounts for 11% of all intestinal volvulus, generally
occurring in patients who are 30-60 years old. Medical history of these
patients may include prior abdominal surgery, presence of a pelvic mass,
violent coughing, atonia of the colon, extreme exertion, unpressurized air
travel, or third-trimester pregnancy
[1]. Patients present with
nausea, vomiting, constipation, and acute cramping pain
[1]. The clinical differential
diagnosis is usually bowel obstruction versus appendicitis, inflammatory bowel
disease, irritable bowel syndrome, or peptic ulcer disease
[1].
Two Types of Twists
When torsion of bowel results in obstruction, the term
"volvulus" is used. In approximately half of the patients, the
cecum twists in the axial plane, rotating clockwise or counterclockwise around
its long axis and appearing in the right lower quadrant
[3,
5]. The other half of patients
have what is known as the loop type of cecal volvulus, in which the cecum both
twists and inverts, occupying the left upper quadrant of the abdomen
[3,
5]
(Fig. 1). The terminal ileum is
usually twisted along with the cecum. Visualization of a gas-filled appendix
confirms the diagnosis [5].
There is a variant of cecal volvulus termed a "cecal bascule,"
which occurs when the cecum folds anteriorly without any torsion. Cecal
bascule is often seen as a dilated loop in the mid abdomen
[3].
View larger version (100K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1. —Drawing shows loop-type cecal volvulus. Cecum may twist
either clockwise or counterclockwise and then inverts upward. Twisted terminal
ileum is seen tangled with cecum. Lower left illustration shows point of
torsion as it would appear on axial CT images. Lg. = large, Sm. = small.
|
|
"Coffee Bean," "Bird Beak," and
"Whirl" Signs
On axial CT images, cecal volvulus is suggested by the extreme dilatation
of the cecum. When seen on conventional radiographs or tomograms, the cecal
volvulus is seen as a rounded focal collection of air-distended bowel with
haustral creases in the left upper quadrant that resembles a coffee bean
(Figs.
2A,2B,2C
and
3A,3B).
The two limbs of the looped obstruction gradually taper and converge at the
site of the torsion, resulting in the appearance of a bird's beak. This
"bird beak" sign, originally applied to the appearance of sigmoid
volvulus on conventional radiographs, can also be appreciated on axial CT
images of the loop-type cecal volvulus
[4] (Fig.
4A,4B,4C).
A specific CT sign for volvulus is the "whirl" (Fig.
5A,5B),
which has been described in volvulus of the midgut, cecum, and sigmoid colon
[2,
4]. The whirl is composed of
spiraled loops of collapsed cecum and sigmoid colon. Low-attenuating fatty
mesentery with enhancing engorged vessels radiate from the twisted bowel. In
the central eye of the whirl, a soft-tissue density pinpoints the source of
the twist [2]. The degree of
cecal rotation can even be predicted by the tightness of the whirl
[6].
View larger version (124K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5A. —Axial CT scan shows cecal volvulus in 57-year-old man.
"Whirl sign" is composed of spiraled loops of collapsed cecum,
distal ileum, and enhancing engorged vessels. Soft-tissue center corresponds
to source of volvulus (long arrow). Note radiating mesenteric fat
(short arrow).
|
|
Treatment
Colonoscopy has been a highly rated tool in diagnosing and reducing the
occurrence of sigmoid volvulus, but it is often not ideal for use in treating
volvulus of the cecum. The reduction rates in cecal volvulus achieved through
use of colonoscopy are much lower than those achieved in sigmoid volvulus, and
in patients with cecal volvulus, the recurrence rate exceeds 50%
[1]. In patients with
uncomplicated cecal volvulus, surgical options include cecopexy, which has a
low rate of morbidity (0-8%) and volvulus recurrence. Gangrene or perforation
requires surgical resection, which eliminates the possibility of recurrence
and also has low morbidity and mortality rates
[1,
7]. CT findings change patient
treatment by revealing the signs of bowel ischemia, including thickening of
bowel wall, mesenteric hemorrhage, and pneumatosis intestinalis
[1].
The Role of 3D Imaging
Diagnosing the cause of bowel obstruction on axial images requires
following the course of several air-distended bowel loops with varying
diameters over many consecutive images. If the bowel collapses or is oriented
anteroposteriorly, visualization of the bowel becomes limited, thereby
increasing the difficulty in locating the exact transition point. Performing a
barium enema circumvents this problem by isolating the involved loop and
accurately revealing the point of obstruction. However, use of the barium
enema is somewhat limited because it may yield no information about emergent
complications such as bowel ischemia or other disease processes outside the
bowel wall. Three-dimensional imaging is ideal because, like a barium enema,
the entire bowel can be visualized in a single image, separating the volvulus
from other dilated loops (Figs.
6A and
6B). Three-dimensional
displays allow radiologists to select the optimal plane for viewing the
volvulus and to locate the precise source of the torsion
(Fig. 6C). In effect, the
ability to analyze an image in multiple planes allows one to unravel twisted
bowel and confirm the diagnosis of volvulus.
View larger version (113K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 6A. —66-year-old woman with cecal torsion. Three-dimensional
reconstructions use volume rendering to define presence of cecal volvulus.
Volume display of entire data set has potential advantages over review of
multiple axial images by defining entire colon and areas of transition. Image
rendering simulates a single-contrast barium study.
|
|
View larger version (134K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 6B. —66-year-old woman with cecal torsion. Three-dimensional
reconstructions use volume rendering to define presence of cecal volvulus.
Volume display of entire data set has potential advantages over review of
multiple axial images by defining entire colon and areas of transition. Image
rendering simulates a double-contrast barium study.
|
|
View larger version (84K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 6C. —66-year-old woman with cecal torsion. Three-dimensional
reconstructions use volume rendering to define presence of cecal volvulus.
Volume display of entire data set has potential advantages over review of
multiple axial images by defining entire colon and areas of transition. In
this sagittal reconstruction, adjacent bowel loops can be distinguished and
site of volvulus can be defined.
|
|
References
-
Montes H, Wolf J. Cecal volvulus in pregnancy. Am J
Gastroenterol 1999;94:2554
-2556[Medline]
-
Frank AJ, Goffner LB, Fruauff AA, Losada RA. Cecal volvulus: the CT
whirl sign. Abdom Imaging
1993;18:288
-289[Medline]
-
Perrer RS, Kunberger LE. Cecal volvulus.
AJR
1998;171:860
-
Catalano O. Computed tomographic appearance of sigmoid volvulus.
Abdom Imaging
1996;21:314
-317[Medline]
-
Field S. Alimentary tract radiology, 5th
ed., vol. 1. St. Louis: Mosby,
1994: 2061-2062
-
Shaff MI, Himmelfarb E, Sacks GA, Burks DD, Kulkarni MV. The whirl
sign: a CT finding in volvulus of the large bowel. J Comput Assist
Tomogr 1985;9:410[Medline]
-
Yang SH, Lin JK, Lee RC, Li AF. Cecal volvulus: report of seven
cases and literature review. Chung Hua I Hsueh Tsa Chih
(Taipei) 2000;63:482
-486
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
|
|
 
A. C. Silva, S. D. Beaty, A. K. Hara, J. G. Fletcher, J. L. Fidler, C. O. Menias, and C. D. Johnson
Spectrum of Normal and Abnormal CT Appearances of the Ileocecal Valve and Cecum with Endoscopic and Surgical Correlation
RadioGraphics,
July 1, 2007;
27(4):
1039 - 1054.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
E T Consorti and T H Liu
Diagnosis and treatment of caecal volvulus
Postgrad. Med. J.,
December 1, 2005;
81(962):
772 - 776.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
B. Khurana
The Whirl Sign
Radiology,
January 1, 2003;
226(1):
69 - 70.
[Full Text]
[PDF]
|
|
|
Top
Introduction
Technique
