- Email: [email protected]
CT scan findings do not predict outcome of nonoperative management in small bowel obstruction: Retrospective analysis of 108 consecutive patients
Accepted Manuscript CT scan findings do not predict outcome of nonoperative management in small bowel obstruction Victor E. Pricolo, MD, Filomena Curley, RN PII:
S1743-9191(16)00041-8
DOI:
10.1016/j.ijsu.2016.01.033
Reference:
IJSU 2480
To appear in:
International Journal of Surgery
Received Date: 21 August 2015 Revised Date:
13 December 2015
Accepted Date: 17 January 2016
Please cite this article as: Pricolo VE, Curley F, CT scan findings do not predict outcome of nonoperative management in small bowel obstruction, International Journal of Surgery (2016), doi: 10.1016/ j.ijsu.2016.01.033. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
TITLE
AUTHORS Victor E. Pricolo, MD, Filomena Curley, RN
RI PT
CT scan findings do not predict outcome of nonoperative management in small bowel obstruction
AC C
EP
TE D
M AN U
SC
Department of Surgery, Southcoast Health, New Bedford, MA, USA
ACCEPTED MANUSCRIPT
INTRODUCTION Small bowel obstruction (SBO) remains a common clinical entity that
health care costs per year in the United States
1,2.
RI PT
accounts for over 300,000 hospital admissions and approximately $3 billion in A certain percentage of these
patients require emergency surgical intervention for findings indicative of peritonitis from perforation or bowel ischemia. The majority of patients with SBO
SC
likely secondary to peritoneal adhesions from previous abdominal surgery (adhesive small bowel obstruction - ASBO) are initially managed non-operatively
M AN U
with hospitalization, intravenous hydration, fasting, nasogastric tube drainage and observation. However, some of these patients develop worsening signs or symptoms, or simply fail to improve after a few days in the hospital, thus requiring operative intervention.
Over the last 10-15 years, computed tomography (CT) has become the standard of care in the initial diagnostic assessment of SBO, and for virtually every
TE D
patient presenting to an Emergency Department with abdominal pain 3. While there are several informative elements associated with SBO on CT, radiologists tend to emphasize in their reports certain findings such as “a transition point”, the “small bowel faeces” sign, a “high-grade obstruction” and an “abnormal vascular course”.
EP
The implication of such “high-risk” findings is that they may correlate with a higher likelihood that the SBO will fail to improve with nonoperative management and may
AC C
warrant early surgical intervention 4. However, from a therapeutic decision making standpoint, whether or not such CT findings actually help risk stratify this group of patients remains a matter of controversy 5. The purpose of our study was to determine whether or not “high-risk”
radiologic findings were in fact associated with a greater need for operative management in patients hospitalized for observation with a presumptive diagnosis of ASBO at a tertiary care institution.
ACCEPTED MANUSCRIPT
RI PT
MATERIALS and METHODS
The Hospital Institutional Review Board approved this study. The
Department of Surgery billing database for a 12 month-period was used to generate a list of consecutive patients who were admitted with a diagnosis of SBO. Variables
SC
entered into the analysis were demographic data including age and gender,
admission history and physical exam, admission laboratory data, radiology reports,
M AN U
operative notes if applicable, and discharge summaries. Additional historical data including past surgical history and presenting signs and symptoms were considered as well. In the review of radiology reports, attention was devoted to entering whether or not key words such as “transition point”, “small bowel feces sign”, “high grade obstruction”, and “abnormal vascular course” were used. Discharge summaries and, if present, operative reports were reviewed to determine if non-
TE D
operative management of small bowel obstruction was successful. Patients who underwent surgical intervention within 24 hours of admission were excluded from the study, as they did not represent patients who were admitted for the purposes of conservative management of small bowel obstruction.
EP
Statistical analysis was done with independent samples t-test and chi-square to identify a correlation between patient characteristics, management groups,
AC C
radiologic variables, and need for operative management (OM) versus success of nonoperative management (NOM).
RESULTS
A total of 200 patients were admitted from the Emergency Department with a diagnosis of small bowel obstruction during the one-year period. Their management allocation is reported in figure 1. Ninety-two patients were excluded
ACCEPTED MANUSCRIPT
from the study for a variety of reasons: 43 patients required prompt operative intervention (e.g peritonitis, free intra-abdominal air or lack of history or previous abdominal surgery), 33 were found to have causes for SBO other than adhesions (e.g. hernia, Crohn’s, diverticulitis, appendicitis, neoplasm) and 16 patients had
RI PT
other diagnoses upon review of the admission history and physical (e.g. large bowel obstruction, paralytic ileus).
The 108 patients that qualified for this study were 53 males and 55 females, ranging in age between 23 and 96 years. They all had a confirmed admitting
SC
diagnosis of ASBO and were initially treated nonoperatively. No patient in this group had findings of ascites by CT scan. The initial diagnosis of SBO was made by CT scan
M AN U
of the abdomen and pelvis, with intravenous contrast, obtained in the Emergency Department. No oral contrast was administered, in consideration of the risk of vomiting and aspiration pneumonia. Of this group, 18 patients (16.7%) underwent an operation during the same admission for small bowel obstruction that failed to improve with nonoperative management (operative management group = OM). Only 3 of these patients underwent a follow-up CT scan during the same hospitalization,
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showing persistent SBO. All these patients had intraoperative findings of peritoneal adhesions as the cause of SBO and were successfully treated without mortality. The remaining 90 patients (83.3%) were successfully managed conservatively and were discharged from the hospital without undergoing an operation (nonoperative
EP
management group = NOM). None of these patients required a follow-up CT scan during the same hospitalization. No patient in the NOM group was readmitted
AC C
within 30 days for recurrent SBO after discharge. Patient characteristics between the operative and nonoperative groups were similar, as shown in table 1. The frequency of the four mentioned radiologic signs in the OM group and in
the NOM group was compared and is reported in table 2. None of the above mentioned radiologic findings on admission CT scan had a
statistically significant association with the success or failure of non-operative management in our study. No patient was managed differently, or had a different outcome, on the basis of the described “high-risk” radiographic findings.
ACCEPTED MANUSCRIPT
DISCUSSION The goal of this study was to provide additional data to assess the value of the information obtained from a CT scan of the abdomen and pelvis in patients who
RI PT
present to an Emergency Department with SBO. While such imaging is considered
the gold standard from a diagnostic point of view, some of the CT findings may have a more limited role in affecting substantial changes in patient management.
There is general agreement that patients who have a SBO with signs of
SC
peritonitis or evidence of clinical deterioration should undergo timely surgical exploration, rather than imaging studies that would not obviate, but only
M AN U
unnecessarily delay, the need for surgical intervention 6. In most patients who have a SBO, the most likely cause is adhesive disease from previous surgery. Such information can be obtained from the patient’s history. Additional surgery will cause additional adhesions and will not reliably prevent additional episodes of SBO. Consequently, surgical intervention is reserved for cases that fail to improve or worsen after a few days of NOM. Patients without history of previous surgery or in
TE D
whom a tumor or an inflammatory process is suspected may warrant surgical exploration after initial stabilization and rehydration. Plain abdominal radiographs, or plain films have long been a useful initial diagnostic test for detecting SBO, as they are cost effective and almost universally
EP
available 7. They demonstrate features such as air-fluid levels, bowel dilatation and paucity of colonic air, suggestive of a small bowel obstruction. Plain films have been
AC C
found to be very accurate with 60 to 93% sensitivity in the diagnosis of SBO, especially if reviewed by experienced radiologists or surgeons 8. CT for SBO has a reported sensitivity of 80 to 94% 9. When compared to plain
radiographs, CT may offer the advantage of better localizing the site of obstruction, the cause of it (e.g. inflammation, neoplasm), and possibly ischemic changes, if intravenous contrast is used 10,11. In addition, certain signs have been suggested as relevant in their potentially predictive value in guiding management decisions. The “transition point” is an abrupt change from dilated to collapsed bowel loops and is indicative of the site of obstruction. The “small bowel faeces” sign arises from the
ACCEPTED MANUSCRIPT
mixing of air and enteric contents in stasis suggesting chronicity of the obstruction12. A “high grade“ obstruction is defined on CT when little or no gas is present in the distal small bowel or ascending colon 13, 14. An “abnormal vascular course”, or “whirl sign” may be indicative of a small bowel volvulus 15, 16.
RI PT
The transition point or transition zone is a frequently emphasized finding on CT scan report for a SBO, described in up to 75% of cases 17. Our study did not
demonstrate a statistically significant correlation between presence of a transition point and failure of NOM. There is no evidence that such finding is a reliable
SC
predictor of need for operative intervention13,14,17,18. The described location of the
site of obstruction by CT scan may, at times, provide some guidance in the choice of
M AN U
incision or laparoscopic port placement at the time of surgery.
The small bowel faeces sign is a less frequently emphasized finding on CT scan that, in our analysis, was not found to be predictive of need for operative intervention. This radiographic sign is likely related to stasis of small bowel content, fluid reabsorption and/or bacterial overgrowth 3,12. It is a finding non-specific for
of NOM 14,19,20.
TE D
SBO and, in some publications, it has been found to inversely correlate with failure
With respect to the degree or grade of obstruction, our review did not identify any correlation between the high grade obstruction and the likelihood of eventual surgical management. An additional complicating factor is the variable
EP
definition of high-grade obstruction in the literature. Although some studies have reported an increased likelihood of OM in patients with this CT finding, other have
AC C
not confirmed such correlation 13,18,21. In our series, an abnormal vascular course was rarely described and all such
patients improved with NOM. Even in the presence of such finding, clinical factors are being taken into account and surgical intervention is not always warranted 15,16. Our study had some limitations in that it was retrospective, observational,
and consequently it did not set precise triggers to declare failure of NOM and proceed with OM. Nonetheless, it appears that both available literature data and our institutional experience do not support reliance on certain CT findings to decide on OM versus NOM in most patients with ASBO that are initially admitted without need
ACCEPTED MANUSCRIPT
for an emergent operation. Recent practice guidelines supported by level 1 evidence recommend NOM, regardless of radiologic findings, in patients with SBO (partial or complete) without evidence of peritoneal signs or clinical and laboratory evidence of deterioration 6,22,23.
RI PT
In our series, in patients with ASBO who had been selected for a trial of
nonoperative management ,“high-risk” findings at the initial CT scan did not provide additional information that significantly affected management. High quality
abdomino-pelvic CT scan remains most valuable as an initial diagnostic tool,
SC
especially with appropriate contrast enhancement, in order to determine ischemic, inflammatory or neoplastic changes associated with SBO at the time of hospital
M AN U
admission that may require early operative intervention. In patients with ASBO that are initially treated nonoperatively, clinical course after hospital admission, with return of bowel function or failure to improve, remains the most relevant factor
Cappell MS, Batke M. Mechanical obstruction of the small bowel and colon.
AC C
1.
EP
REFERENCES
TE D
affecting management decisions to proceed with surgical intervention.
Med Clin North Am. 2008;92(3):575-97, viii.
2.
Foster NM, McGory ML, Zingmond DS, Ko CY. Small bowel obstruction: a population-based appraisal. J Am Coll Surg. 2006;203(2):170-6.
3.
Santillan C. Computed tomography of small bowel obstruction. Radiol Clin
North Am. 2013;51:17-27. 4.
Catena F, Di Saverio S, Kelly MD, et al. Bologna guidelines for diagnosis and management of adhesive small bowel obstruction (ASBO): evidence-based
ACCEPTED MANUSCRIPT
guidelines of the world Society of Emergency Surgery. World J Emerg Surg. 2011; 6:5. 5.
Suri RR, Vora P, Kirby JM, Ruo L. Computed tomography features associated
Can J Surg. 2014: 57(4):254-9 6.
RI PT
with operative management for nonstrangulating small bowel obstruction.
Maung AA, Johnson DC, Piper GL, et al. Evaluation and management of smallbowel obstruction: an Eastern Association for the Surgery of Trauma practice management guideline. J Trauma Acute Care Surg. 2012; 73(5):S362-9.
Lappas JC, Reyes BL, Maglinte DD. Abdominal radiography findings in small-
SC
7.
bowel obstruction: relevance to triage for additional diagnostic imaging. AJR
8.
M AN U
Am J Roentgenol. 2001;176(1):167-174.
Thompson WM, Kilani RK, Smith BB, et al. Accuracy of abdominal radiography in acute small-bowel obstruction: does reviewer experience matter? AJR Am J Roentgenol. 2007;188(3):W233-238.
9.
Maglinte DD, Heitkamp DE, Howard TJ, et al. Current concepts in imaging of small bowel obstruction. Roadiol Clin North Am. 2003;41:263-83. Suri S, Gupta S, Sudhaka PJ, et al. Comparative evaluation of plain films,
TE D
10.
ultrasound and CT in the diagnosis of intestinal obstruction. Acta Radiol. 1990;40:422-8. 11.
Obuz F, Terzi C, Sokmen S, et al. The efficacy of helical CT in the diagnosis of
12.
EP
small bowel obstruction. Eur J Radiol. 2003;48:299-304. Mayo-Smith WW, Wittenberg J, Bennett GL, et al. The CT small bowel faeces
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sign: description and clinical significance. Clin Radiol. 1995;50(11):765-7. 13.
Hwang JY, Lee JK, Lee JE, Baek SY. Value of multidetector CT in decision
making regarding surgery in patients with small-bowel obstruction due to
adhesion. Eur Radiol. 2009;19(10):2425-31.
14.
Deshmukh SD, Shin DS, Willmann JK, et al. Non-emergency small bowel
obstruction: assessment of CT findings that predict need for surgery. Eur Radiol. 2011;21(5):982-6.
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15.
Sandhu PS, Joe BN, Coakley FV, et al. Bowel transition points: multiplicity and posterior location at CT are associated with small-bowel volvulus. Radiology. 2007;245:160-7.
16.
Duda JB, BhattS, Dogra VS. Utility of CT whirl sign in guiding management of
17.
RI PT
small-bowel obstruction. AJR Am J Roentgenol. 2008;191:743-7.
Colon MJ, Telem DA, Wong D, et al. The relevance of transition zones on computed tomography in the management of small bowel obstruction. Surgery 2010;147(3):373-7.
Jones K, Mangram AJ, LebronRA, et al. Can a computed tomography scoring
SC
18.
system predict the need for surgery in small bowel obstruction? Am J Surg.
19.
M AN U
2007;194(6):780-4.
Jacobs SL, Rozenblit A, Ricci Z, et al. Small bowel faeces sign in patients without small bowel obstruction. Clin Radiol. 2007;62(4):353-7.
20.
Zielinski MD, Eiken PW, Bannon MP, et al. Small bowel obstruction - who needs an operation? A multivariate prediction model. World J Surg 2010;34(5):910-9.
Tanaka S, YamamotoT, Kubota D, et al. Predictive factors for surgical
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21.
indication in adhesive small bowel obstruction. Am J Surg 2008;196(1):23-7. 22.
Scwenter F, Poletti PA, Platon A. et al. Clinicoradiological score for predicting
25 23.
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the risk of strangulated small bowel obstruction. Br J Surg 2010;97(7):1119-
Zielinski MD, Eiken PW, Heller SF, et al. Prospective, observational validation
AC C
of a multivariate small-bowel obstruction model to predict the need for operative intervention. J AM Coll Surg 2011;21(6):1068-76.
ACCEPTED MANUSCRIPT
NOM group
p value
Age, years (mean)
58.35
60.23
0.49
Male gender, n (%)
11 (61.1)
42 (46.7)
0.10
Hx abdominal surgery, n (%)
18 (100)
90 (100)
White
13 (72.2)
Non-white
5 (27.8)
68 (75.6)
0.84
22 (24.4)
0.69
Hispanic
4 (22.2)
25 (27.8)
0.53
Non-hispanic
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Race, n (%)
RI PT
OM group
SC
Patient demographics and characteristics
14 (77.8)
65 (72.2)
.082
Diabetes Mellitus, n (%)
3 (16.7)
14 (15.6)
0.58
COPD, n (%)
2 (11.1)
8 (8.9)
0.44
1 (5.6)
4 (4.4)
0.34
3 (16.7)
12 (13.3)
0.52
2 (11.1)
7 (7.8)
0.45
9.5
8.9
0.91
Obesity, n (%)
EP
History of CHF, n (%)
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Ethnicity, n (%)
AC C
Renal failure, n (%)
WBC count (cells/mcL), mean
Table 1.
ACCEPTED MANUSCRIPT
N pts
OM group
NOM group
p value
Transition point
78
13 (16.7%)
65(83.3%)
0.68
Small bowel feces
35
3 (8.6%)
32(91.4%)
0.19
High grade obstruction
14
2 (14.3%)
12(85.7%)
0.81
Abnormal vascular course
3
0
3
0.44
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CT finding
AC C
EP
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Table 2.
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43 patients OR <24 hrs
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Figure 1.
18 patients (16.7%) OM required
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90 patients (83.3%) NOM successful
33 patients incorrect ASBO diagnosis
SC
108 patients admitted for non-op mgmt.
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200 patients with ED diagnosis of ASBO
16 patients incorrect SBO diagnosis
ACCEPTED MANUSCRIPT
Highlights:
Small bowel obstruction, likely secondary to adhesions from previous abdominal surgery, is a very common occurrence and a relevant acute care problem
-
Computed tomography is routinely used in the diagnostic evaluation of small bowel obstruction
-
Certain CT scan findings have been proposed as indicative of need for surgical intervention in adhesive small bowel obstruction
-
Our experience does not show that CT scan findings alone can reliably predict failure of nonoperative management in adhesive small bowel obstruction
AC C
EP
TE D
M AN U
SC
RI PT
-
ACCEPTED MANUSCRIPT
Abbreviations and Acronyms
ASBO = adhesive small bowel obstruction
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CT = computerized tomography ED = emergency department NOM = non-operative management
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OM = operative management SBO = small bowel obstruction
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WBC = white blood cell
ACCEPTED MANUSCRIPT
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SC
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No conflict of interest No disclosures
S1743-9191(16)00041-8
DOI:
10.1016/j.ijsu.2016.01.033
Reference:
IJSU 2480
To appear in:
International Journal of Surgery
Received Date: 21 August 2015 Revised Date:
13 December 2015
Accepted Date: 17 January 2016
Please cite this article as: Pricolo VE, Curley F, CT scan findings do not predict outcome of nonoperative management in small bowel obstruction, International Journal of Surgery (2016), doi: 10.1016/ j.ijsu.2016.01.033. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
TITLE
AUTHORS Victor E. Pricolo, MD, Filomena Curley, RN
RI PT
CT scan findings do not predict outcome of nonoperative management in small bowel obstruction
AC C
EP
TE D
M AN U
SC
Department of Surgery, Southcoast Health, New Bedford, MA, USA
ACCEPTED MANUSCRIPT
INTRODUCTION Small bowel obstruction (SBO) remains a common clinical entity that
health care costs per year in the United States
1,2.
RI PT
accounts for over 300,000 hospital admissions and approximately $3 billion in A certain percentage of these
patients require emergency surgical intervention for findings indicative of peritonitis from perforation or bowel ischemia. The majority of patients with SBO
SC
likely secondary to peritoneal adhesions from previous abdominal surgery (adhesive small bowel obstruction - ASBO) are initially managed non-operatively
M AN U
with hospitalization, intravenous hydration, fasting, nasogastric tube drainage and observation. However, some of these patients develop worsening signs or symptoms, or simply fail to improve after a few days in the hospital, thus requiring operative intervention.
Over the last 10-15 years, computed tomography (CT) has become the standard of care in the initial diagnostic assessment of SBO, and for virtually every
TE D
patient presenting to an Emergency Department with abdominal pain 3. While there are several informative elements associated with SBO on CT, radiologists tend to emphasize in their reports certain findings such as “a transition point”, the “small bowel faeces” sign, a “high-grade obstruction” and an “abnormal vascular course”.
EP
The implication of such “high-risk” findings is that they may correlate with a higher likelihood that the SBO will fail to improve with nonoperative management and may
AC C
warrant early surgical intervention 4. However, from a therapeutic decision making standpoint, whether or not such CT findings actually help risk stratify this group of patients remains a matter of controversy 5. The purpose of our study was to determine whether or not “high-risk”
radiologic findings were in fact associated with a greater need for operative management in patients hospitalized for observation with a presumptive diagnosis of ASBO at a tertiary care institution.
ACCEPTED MANUSCRIPT
RI PT
MATERIALS and METHODS
The Hospital Institutional Review Board approved this study. The
Department of Surgery billing database for a 12 month-period was used to generate a list of consecutive patients who were admitted with a diagnosis of SBO. Variables
SC
entered into the analysis were demographic data including age and gender,
admission history and physical exam, admission laboratory data, radiology reports,
M AN U
operative notes if applicable, and discharge summaries. Additional historical data including past surgical history and presenting signs and symptoms were considered as well. In the review of radiology reports, attention was devoted to entering whether or not key words such as “transition point”, “small bowel feces sign”, “high grade obstruction”, and “abnormal vascular course” were used. Discharge summaries and, if present, operative reports were reviewed to determine if non-
TE D
operative management of small bowel obstruction was successful. Patients who underwent surgical intervention within 24 hours of admission were excluded from the study, as they did not represent patients who were admitted for the purposes of conservative management of small bowel obstruction.
EP
Statistical analysis was done with independent samples t-test and chi-square to identify a correlation between patient characteristics, management groups,
AC C
radiologic variables, and need for operative management (OM) versus success of nonoperative management (NOM).
RESULTS
A total of 200 patients were admitted from the Emergency Department with a diagnosis of small bowel obstruction during the one-year period. Their management allocation is reported in figure 1. Ninety-two patients were excluded
ACCEPTED MANUSCRIPT
from the study for a variety of reasons: 43 patients required prompt operative intervention (e.g peritonitis, free intra-abdominal air or lack of history or previous abdominal surgery), 33 were found to have causes for SBO other than adhesions (e.g. hernia, Crohn’s, diverticulitis, appendicitis, neoplasm) and 16 patients had
RI PT
other diagnoses upon review of the admission history and physical (e.g. large bowel obstruction, paralytic ileus).
The 108 patients that qualified for this study were 53 males and 55 females, ranging in age between 23 and 96 years. They all had a confirmed admitting
SC
diagnosis of ASBO and were initially treated nonoperatively. No patient in this group had findings of ascites by CT scan. The initial diagnosis of SBO was made by CT scan
M AN U
of the abdomen and pelvis, with intravenous contrast, obtained in the Emergency Department. No oral contrast was administered, in consideration of the risk of vomiting and aspiration pneumonia. Of this group, 18 patients (16.7%) underwent an operation during the same admission for small bowel obstruction that failed to improve with nonoperative management (operative management group = OM). Only 3 of these patients underwent a follow-up CT scan during the same hospitalization,
TE D
showing persistent SBO. All these patients had intraoperative findings of peritoneal adhesions as the cause of SBO and were successfully treated without mortality. The remaining 90 patients (83.3%) were successfully managed conservatively and were discharged from the hospital without undergoing an operation (nonoperative
EP
management group = NOM). None of these patients required a follow-up CT scan during the same hospitalization. No patient in the NOM group was readmitted
AC C
within 30 days for recurrent SBO after discharge. Patient characteristics between the operative and nonoperative groups were similar, as shown in table 1. The frequency of the four mentioned radiologic signs in the OM group and in
the NOM group was compared and is reported in table 2. None of the above mentioned radiologic findings on admission CT scan had a
statistically significant association with the success or failure of non-operative management in our study. No patient was managed differently, or had a different outcome, on the basis of the described “high-risk” radiographic findings.
ACCEPTED MANUSCRIPT
DISCUSSION The goal of this study was to provide additional data to assess the value of the information obtained from a CT scan of the abdomen and pelvis in patients who
RI PT
present to an Emergency Department with SBO. While such imaging is considered
the gold standard from a diagnostic point of view, some of the CT findings may have a more limited role in affecting substantial changes in patient management.
There is general agreement that patients who have a SBO with signs of
SC
peritonitis or evidence of clinical deterioration should undergo timely surgical exploration, rather than imaging studies that would not obviate, but only
M AN U
unnecessarily delay, the need for surgical intervention 6. In most patients who have a SBO, the most likely cause is adhesive disease from previous surgery. Such information can be obtained from the patient’s history. Additional surgery will cause additional adhesions and will not reliably prevent additional episodes of SBO. Consequently, surgical intervention is reserved for cases that fail to improve or worsen after a few days of NOM. Patients without history of previous surgery or in
TE D
whom a tumor or an inflammatory process is suspected may warrant surgical exploration after initial stabilization and rehydration. Plain abdominal radiographs, or plain films have long been a useful initial diagnostic test for detecting SBO, as they are cost effective and almost universally
EP
available 7. They demonstrate features such as air-fluid levels, bowel dilatation and paucity of colonic air, suggestive of a small bowel obstruction. Plain films have been
AC C
found to be very accurate with 60 to 93% sensitivity in the diagnosis of SBO, especially if reviewed by experienced radiologists or surgeons 8. CT for SBO has a reported sensitivity of 80 to 94% 9. When compared to plain
radiographs, CT may offer the advantage of better localizing the site of obstruction, the cause of it (e.g. inflammation, neoplasm), and possibly ischemic changes, if intravenous contrast is used 10,11. In addition, certain signs have been suggested as relevant in their potentially predictive value in guiding management decisions. The “transition point” is an abrupt change from dilated to collapsed bowel loops and is indicative of the site of obstruction. The “small bowel faeces” sign arises from the
ACCEPTED MANUSCRIPT
mixing of air and enteric contents in stasis suggesting chronicity of the obstruction12. A “high grade“ obstruction is defined on CT when little or no gas is present in the distal small bowel or ascending colon 13, 14. An “abnormal vascular course”, or “whirl sign” may be indicative of a small bowel volvulus 15, 16.
RI PT
The transition point or transition zone is a frequently emphasized finding on CT scan report for a SBO, described in up to 75% of cases 17. Our study did not
demonstrate a statistically significant correlation between presence of a transition point and failure of NOM. There is no evidence that such finding is a reliable
SC
predictor of need for operative intervention13,14,17,18. The described location of the
site of obstruction by CT scan may, at times, provide some guidance in the choice of
M AN U
incision or laparoscopic port placement at the time of surgery.
The small bowel faeces sign is a less frequently emphasized finding on CT scan that, in our analysis, was not found to be predictive of need for operative intervention. This radiographic sign is likely related to stasis of small bowel content, fluid reabsorption and/or bacterial overgrowth 3,12. It is a finding non-specific for
of NOM 14,19,20.
TE D
SBO and, in some publications, it has been found to inversely correlate with failure
With respect to the degree or grade of obstruction, our review did not identify any correlation between the high grade obstruction and the likelihood of eventual surgical management. An additional complicating factor is the variable
EP
definition of high-grade obstruction in the literature. Although some studies have reported an increased likelihood of OM in patients with this CT finding, other have
AC C
not confirmed such correlation 13,18,21. In our series, an abnormal vascular course was rarely described and all such
patients improved with NOM. Even in the presence of such finding, clinical factors are being taken into account and surgical intervention is not always warranted 15,16. Our study had some limitations in that it was retrospective, observational,
and consequently it did not set precise triggers to declare failure of NOM and proceed with OM. Nonetheless, it appears that both available literature data and our institutional experience do not support reliance on certain CT findings to decide on OM versus NOM in most patients with ASBO that are initially admitted without need
ACCEPTED MANUSCRIPT
for an emergent operation. Recent practice guidelines supported by level 1 evidence recommend NOM, regardless of radiologic findings, in patients with SBO (partial or complete) without evidence of peritoneal signs or clinical and laboratory evidence of deterioration 6,22,23.
RI PT
In our series, in patients with ASBO who had been selected for a trial of
nonoperative management ,“high-risk” findings at the initial CT scan did not provide additional information that significantly affected management. High quality
abdomino-pelvic CT scan remains most valuable as an initial diagnostic tool,
SC
especially with appropriate contrast enhancement, in order to determine ischemic, inflammatory or neoplastic changes associated with SBO at the time of hospital
M AN U
admission that may require early operative intervention. In patients with ASBO that are initially treated nonoperatively, clinical course after hospital admission, with return of bowel function or failure to improve, remains the most relevant factor
Cappell MS, Batke M. Mechanical obstruction of the small bowel and colon.
AC C
1.
EP
REFERENCES
TE D
affecting management decisions to proceed with surgical intervention.
Med Clin North Am. 2008;92(3):575-97, viii.
2.
Foster NM, McGory ML, Zingmond DS, Ko CY. Small bowel obstruction: a population-based appraisal. J Am Coll Surg. 2006;203(2):170-6.
3.
Santillan C. Computed tomography of small bowel obstruction. Radiol Clin
North Am. 2013;51:17-27. 4.
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NOM group
p value
Age, years (mean)
58.35
60.23
0.49
Male gender, n (%)
11 (61.1)
42 (46.7)
0.10
Hx abdominal surgery, n (%)
18 (100)
90 (100)
White
13 (72.2)
Non-white
5 (27.8)
68 (75.6)
0.84
22 (24.4)
0.69
Hispanic
4 (22.2)
25 (27.8)
0.53
Non-hispanic
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Race, n (%)
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OM group
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Patient demographics and characteristics
14 (77.8)
65 (72.2)
.082
Diabetes Mellitus, n (%)
3 (16.7)
14 (15.6)
0.58
COPD, n (%)
2 (11.1)
8 (8.9)
0.44
1 (5.6)
4 (4.4)
0.34
3 (16.7)
12 (13.3)
0.52
2 (11.1)
7 (7.8)
0.45
9.5
8.9
0.91
Obesity, n (%)
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History of CHF, n (%)
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Ethnicity, n (%)
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Renal failure, n (%)
WBC count (cells/mcL), mean
Table 1.
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N pts
OM group
NOM group
p value
Transition point
78
13 (16.7%)
65(83.3%)
0.68
Small bowel feces
35
3 (8.6%)
32(91.4%)
0.19
High grade obstruction
14
2 (14.3%)
12(85.7%)
0.81
Abnormal vascular course
3
0
3
0.44
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CT finding
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Table 2.
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43 patients OR <24 hrs
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Figure 1.
18 patients (16.7%) OM required
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90 patients (83.3%) NOM successful
33 patients incorrect ASBO diagnosis
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108 patients admitted for non-op mgmt.
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200 patients with ED diagnosis of ASBO
16 patients incorrect SBO diagnosis
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Highlights:
Small bowel obstruction, likely secondary to adhesions from previous abdominal surgery, is a very common occurrence and a relevant acute care problem
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Computed tomography is routinely used in the diagnostic evaluation of small bowel obstruction
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Certain CT scan findings have been proposed as indicative of need for surgical intervention in adhesive small bowel obstruction
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Our experience does not show that CT scan findings alone can reliably predict failure of nonoperative management in adhesive small bowel obstruction
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Abbreviations and Acronyms
ASBO = adhesive small bowel obstruction
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CT = computerized tomography ED = emergency department NOM = non-operative management
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OM = operative management SBO = small bowel obstruction
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WBC = white blood cell
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No conflict of interest No disclosures