Case Report
Comparison of the Computerized Tomography and Intraoperative Findings in Resection Requiring Small and Large Intestinal Ischemia
Bülent Güngör1*, Serdar Aslan2 and Mehmet Selim Nural2
1Department of General Surgery, 19 Mayis University, Medical School, Turkey
2Department of Radiology, 19 Mayis University, Medical School, Turkey
*Corresponding author: Bülent Güngör, Department of General Surgery, 19 Mayis University, Medical School, Turkey
Published: 18 Sep, 2017
Cite this article as: Güngör B, Aslan S, Nural MS.
Comparison of the Computerized
Tomography and Intraoperative
Findings in Resection Requiring Small
and Large Intestinal Ischemia. Clin
Surg. 2017; 2: 1614.
Abstract
Objective: We tried to find the correlation between computerized tomography (CT) and
intraoperative findings in patients with small and large intestinal ischemia.
Methods: 40 patients operated with the diagnosis of intestinal ischemia in 19 Mayıs University
Medical School Hospital between 01 January 2008 and 01 January 2016 were retrospectively
evaluated. All the patients having laparotomy were included in the study. The patients who had been
clinically observed and with suspicious diagnosis were excluded from the study. CT findings; bowel
wall thickness, dilatation, halo or target sign, increased or decreased contrast material in bowel
wall, faeces sign, pneumatosis intestinalis, bowel obstruction, congestion, distortion and stranding
of mesenteric fat, contributing solid organ ischemia, ascites, superior mesenteric arterial (SMA)
thrombus, mesenteric vein thrombus and pneumoporta were reported. All these characteristics
were compared with intraoperative findings. Cross tables were formed and Chi-Square Test (SPSS
21.0 version) was used for the statistical analysis.
Results:M Contrast loss and SMA thrombus were found as indicators of both small and large intestinal
iscemia.. Bowel wall thicknesss was not correlated with the degree of ischemia, especially in colon.
Faeces sign and pneumatosis intestinalis were more specific for large intestinal ischemia.
Conclusion: Abdominal CT findings correlate with the intraoperative findings in intestinal
ischemia; in the aspect of contrast loss, SMA obstruction, faeces sign and pneumatosis intestinalis.
Introduction
Mesenteric ischemia is becoming a common mortal disease together with the increasing life period and atherosclerotic vascular diseases. Especially in geriatric population it is one of the main emergent surgical diseases for acute abdomen [1]. Early diagnosis and rapid treatment are life saving [2-4]. We cannot actually comment about the acute and chronic mesenteric vascular occlusion retrospectively. Because we meet the patients generally with gangrenous and necrotic intestinal segments. The difficulty in early diagnosis is the main problem. The most important available diagnostic technique is Computerized Tomography (CT) imaging. Contrast enhanced multidetector computed tomography in the arterial and portal venous phases is an accurate method for detecting vascular pathology and intestinal changes in mesenteric ischemia with a sensitivity of 89% - 100% and a specificity of 90% - 100% [5-7]. We aimed to find the correlation between CT and intraoperative findings in patients with ischemic bowel disease.
Patients and Methods
The records of 40 patients admitted to 19 Mayis University Medical School Hospital between January 2008 and January 2016 and diagnosed with mesenteric ischemia are evaluated. CT imaging was obtained by contrast enhancement in arterial, venous and portal phases (Somaton Definition, ASO4, Siemens Med. Systems). The effected intestinal segment, thickness of bowel wall, dilatation of bowel, halo or target sign, increased or decreased contrast material in bowel wall, faeces sign, pneumatosis intestinalis, bowel obstruction, congestion, distortion and stranding of mesenteric fat, contributing solid organ ischemia, ascites, superior mesenteric arterial thrombus, mesenteric vein thrombus and pneumoporta were reported. 19 Mayis University, Medical School Ethical Committee Approve was obtained before the study. Increased thickness of bowel wall was accepted as > 3 mm. It is related with reperfusion. In mesenteric arterial occlusion, bowel wall becomes thinner if there is no hemorrhage or intestinal wall edema. Bowel wall thickness is not related with the severity of ischemia. Dilatation of bowel means; > 2.5 cm for small intestines, > 6 cm for colon, > 8 cm for cecum. It is related with decreased peristaltism. Contrast loss is highly specific for acute arterial ischemia. Contrast enhancement is related with venous ischemia and reperfusion. Delayed contrast enhancement is related with arterial perfusion and differences in venous return. Pneumatosis intestinalis shows transmural ischemia. Mesenteric stranding, congestion and distortion are related with strangulation and venous ischemia. Distortion is also related with arterial ischemia and transmural infarction. Pneumoporta and free intraabdominal gas are signs of transmural infarction. Intraabdominal findings of small and large intestinal resection requırıng ischemia referred as necrosis were determined. Cross tables were formed and Chi-square test (SPSS 21.0 version) was used for the statistical analysis to compare the computed tomography findings and intraoperative small and large intestinal necrosis.
Table 1
Table 2
Table 3
Table 4
Table 5
Table 6
Table 7
Table 8
Table 9
Table 10
Table 11
Table 12
Results
The small intestines were affected more than colonic segments(Table 1).
Bowel wall thicknesss was not correlated with the degree of
ischemia, especially in colon (Table 2).
The dilatation of bowel did not correlate with the ischemic
segments. The dilatation of the small intestine was more specific than
that of colon. The diameter of the colon was more increased in colon
necrosis (Table 3).
Halo or target sign was generally negative (Table 4).
Most patients had loss of enhancement (Table 5).
Faeces sign is not correlated with the necrosis. It is not specific.
But it was mostly seen in large intestinal ischemia in our patients
(Table 6).
Pneumatosis intestinalis is not also specific for necrosis. But it was
also mostly seen in large intestinal ischemia in our patients (Table 7).
Contrast loss was present in every patient (Table 8).
Mechanical intestinal obstruction was detected in only 5 patients
(Table 9).
Mesenteric fat stranding is not specific. It was present also with engorgement in 3 patients (Table 10).
In 6 patients there were accompanying solid organ ischemia
(Table 11)
Ascites was not specific (Table 12).
Superior mesenteric arterial occlusion was mostly positive. (SMA
(Superior Mesenteric Artery)) (Table 13).
Mesenteric vein thrombosis was present in only 2 patients (Table
14).
Pneumoporta was not specific (Table 15).
Discussion
Computerized tomography and intraoperative findings are
correlated in the aspect of affected bowel segment. But intraoperative
findings revealed intestinal necrosis in longer segments and sometimes
additional colonic necrosis was also diagnosed. While contrast
enhancement is present in tomography, small intestinal necrosis was
seen in 100%, small and large intestinal necrosis was seen in 89.5%
of patients. This means, contrast enhancement is predictive for small
intestinal necrosis and for also majority of large intestinal necrosis.
Because our patients are generally elderly and admitted late to the
hospital, their renal functions are mostly not good, so we could not give contrast material for the tomography scan, and we could not get
help of contrast enhancement. If there was no contrast enhancement
only in colon, there was necrosis of small intestine in laparotomy.
But when there is contrast enhancement only in colon, the necrosis
of small intestine in laparotomy was much less. This means, contrast
enhancement is significant for the preoperative diagnosis of necrosis,
but no enhancement in colon is not significant for the presence of
necrosis both in colon and small intestine in laparotomy. Negative
predictive value of loss of contrast enhancement is low. When there
was no thickening of bowel wall, necrosis is more in small intestine
and colon. When thickening is present, necrosis is less but in small
intestine. This may be related with the anatomic thickness of the small
intestine. It means that if there is necrosis of colon, no thickening of
colonic wall is present.
Although halo (target) sign has a high diagnostic value in
ischemia, most of our patients with intestinal necrosis has no halo.
Our patients are generally delayed cases with resection requiring
necrosis. So, halo may not be significant sign in necrosis, it may be
valuable in reversible bowel ischemia. Contrast loss mainly shows
bowel necrosis, so the importance of contrast CT is confirmed again.
While absence of faeces sign is not significant in necrosis, presence of
faeces sign was more significant for colonic necrosis in our patients.
Pneumatosis intestinalis is not also valuable as contrast enhancement
or loss. But if it was present, it was seen more diagnostic for colonic
necrosis in our patients. Bowel obstruction was not generally present
in our patients with bowel necrosis. The etiology of necrosis in our
patients are generally vascular in origin. CT sign of bowel obstruction
is usually present in mesenteric torsion or volvulus. We have seen
that mesenteric fat stranding had no diagnostic value in our patients.
This finding may be significant in early phases of mesenteric vascular
obstruction like reversible ischemia. Accompanying solid organ
ischemia was present in patients with small intestinal and colonic
ischemia. So, this is generally related with systemic vascular disease
including multiple vessels. Ascites was not significant for the
diagnosis of ischemia or necrosis. Mesenteric venous thrombosis was
detected in only one patient. All of our patients had ischemic bowel
disease related with arterial obstruction.
Pneumoporta was not a significant criteria for small bowel
necrosis in our study. It is detected significantly in colonic necrosis.
It may be related with colonic gas and passage of this gas into portal
system in colonic necrosis.
Mortality was related with patient's primary disease, age,
functional capacity of the vital organs and sepsis; not with the
anatomic location of bowel necrosis.
It was absolutely apparent in majority of the cases that the
obstructing lesion inside the mesenteric artery (embolus or
thrombus) could be detected in the tomography. In reversible
ischemic conditions, this finding would give the chance of vascular
management like embolectomy, thrombectomy or reconstruction.
CT findings in bowel ischemia were reported in the literature [8,9].
There are no specific diagnostic sign. Differentiating bowel ischemia
and necrosis is so much difficult. There are very few reports [10,11].
Intestinal pneumatosis, small bowel feces sign [8,12] and portal
venous gas are known as signs of infarction [13,14]. All these signs
are not found specific for small intestinal or colonic necrosis in our
patients. These may not be a significant sign in delayed infarction and
necrosis. Because most of our patients admitted to the hospital in late
phases of bowel ischemia, so related mortality is high.
Reduced contrast enhancement of the bowel wall is the most
reliable sign of bowel ischemia in many studies [8,9,15-17]. We also
determined reduced contrast enhancement in almost all patients. It
may be an important indicator of necrosis more than ischemia. It is a
significant predictor in multivariate analysis (p< 0.05), but sensitivity
is 67% (18 of 27) [18]. Single phase images could sometimes miss the
abnormal contrast enhancement in patients with poor circulation.
Two phase contrast acquisitions can determine the decreased bowel
wall enhancement. Mesenteric arteries and veins are also important
in the aspect of contrast enhancement. Reduced enhancement of
mesenteric veins are more sensitive than that of arteries (88%,70%
vs. 44%,33%) [18].
Engorgement of mesenteric veins was reported in mesenteric
ischemia [14,19]. It is more in early stages of ischemia with mild
impairment of venous return and a viable bowel. Pathologically, first
venous return is impaired. Increased venous and capillary pressure
in the bowel wall and mesentery leads to edema, engorgement
of the veins, rupture of small vessels, intramural and mesenteric
hemorrhage. Arterial insufficiency comes later [14,20]. CT findings
reflect these pathologic changes. Reduced bowel wall enhancement,
reduced enhancement of mesenteric veins and lack of engorgement
of mesenteric veins increase the diagnostic accuracy of the findings.
Engorgement of mesenteric veins was a predictor of a viable bowel.
All of our patients had necrotic bowels. We cannot commend
about CT findings showing reversible ischemic bowel.
CT findings of slight thickening of the bowel wall, the target sign,
engorgement of the mesenteric vasculature, mesenteric edema are early
and reversible signs of small bowel strangulation. Bowel infarction
or gangrene is indicated with CT findings of high attenuation of the
bowel wall, pneumatosis, hemorrhagic changes in the mesentery, gas
in the portal vein, and poor or no enhancement of the bowel wall
[13,20]. Serrated beak, a large amount of ascites, an unusual course of
mesenteric vasculature and mesenteric haziness were the most useful
findings for identifying strangulated obstruction. Combination of
these findings increases the diagnostic accuracy of CT [21]. CT has
a high negative predictive value and is useful for ruling out bowel
ischemia in patients with suspicious bowel ischemia. It is related with
multidetector CT [22]. Small intestinal segments are mainly involved
in our patients. In the patients with colonic involvement, only the
right colon till the midpart of the transverse colon was ischemic.
This means that the superior mesenteric arterial obstruction is more
prominant than the inferior mesenteric arterial obstruction. This may
be related with the anatomic position and the blood flow dynamics of
the SMA. Compensatory collateral circulation is only enough for the
proximal 25 cm - 30 cm long segments of small intestines. The rate of
mortality and short bowel syndrome are high in these patients. Bowel
wall thickness is not correlated with the severity of ischemia especially
in the colon. This may be related with the changes in bowel wall in
hemorrhagic, edematous, arterial or venous ischemic conditions. In
ischemia with hemorhage or edema or mesenteric venous obstruction;
bowel wall may be seen thickened in CT examination. But if there is
only arterial ischemia and necrosis of bowel wall it may be seen as a
thin wall. Dilatation is also not correlated with the ischemic segments.
Because the segments proximal to the ischemic segment may also
dilate due to the decreased motility of the ischemic distal segments.
Colon is also full of gas, so the dilatation is not specific for colon and
the dilatation is more than the small intestine in colon. Halo or target
sign is generally negative in our patients. This may be related with late
stages of bowel ischemia. Most patients had bowel resection due to
irreversible ischemia or necrosis.
We couldn't have an idea about the reversible ischemic
changes in nonoperated and observed patients to compare with the
intraabdominal exact pathology. This was the limitation of our study.
Table 13
Table 14
Table 15
Conclusion
Contrast loss and SMA thrombus were found as indicators of both small and large intestinal iscemia. Bowel wall thicknesss was not correlated with the degree of ischemia, especially in colon. Faeces sign and pneumatosis intestinalis were more specific for large intestinal ischemia.
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