Surgery in adhesive small bowel obstruction on basis of computed tomography: A prospective analysis

Shailendra P Singh; Anand Pandey; Vipin Gupta; Jigyasa Pandey; Rajesh Verma; Ambrish S Mathur

doi:10.4103/1116-5898.149601

ORIGINAL ARTICLE

Year : 2014 | Volume : 24 | Issue : 2 | Page : 36-41

Surgery in adhesive small bowel obstruction on basis of computed tomography: A prospective analysis

Shailendra P Singh¹, Anand Pandey¹, Vipin Gupta¹, Jigyasa Pandey², Rajesh Verma¹, Ambrish S Mathur¹
¹ Department of Surgery, UP Rural Institute of Medical Sciences and Research, Saifai, Etawah, Uttar Pradesh, India
² Department of Radiodiagnosis, UP Rural Institute of Medical Sciences and Research, Saifai, Etawah, Uttar Pradesh, India

Date of Acceptance	12-Nov-2014
Date of Web Publication	21-Jan-2015

Correspondence Address:
Jigyasa Pandey
Department of Radiodiagnosis, UP Rural Institute of Medical Sciences and Research, Saifai, Etawah, Uttar Pradesh
India

Source of Support: None, Conflict of Interest: None

Check

DOI: 10.4103/1116-5898.149601

Abstract

Background: Adhesive small bowel obstruction (ASBO) is the commonest form of small bowel obstruction. The treatment regime for ASBO is not universal. Contrast-enhanced computed tomography (CECT) has been advocated as a valuable procedure to evaluate ASBO. The aim of the present study was to evaluate the contribution of CECT in decision making in the management of patients with ASBO due to postoperative adhesions. Materials and Methods: The duration of this study was 2 years. All patients clinically diagnosed as ASBO with history of clinical symptoms for more than 24 h and any abdominal operation more than a month ago were included in this study. They underwent CECT, which was evaluated for the presence of dilated bowel loops proximal to the transition zone and collapsed distal small bowel loop, presence of complication viz. strangulation and closed loop/volvulus. Results: A total of 30 patients was evaluated. Based on CT findings, the level of obstruction was determined in all the 30 patients. The level of obstruction could be confirmed in nine patients, in which laparotomy was performed, and was same. Complicated small bowel obstruction was predicted in ten patients. The diagnostic accuracy of CT scan was excellent having sensitivity of 100%, specificity of 95.3%, and accuracy of 96.7%. Conclusion: Contrast-enhanced computed tomography abdomen appears to be a safe, quick to perform, and reliable adjunct to clinical examination in the management of patients with ASBO. It is sensitive, specific, and accurate for diagnosis of obstruction, detection of level of obstruction, and complication of obstruction. CT scan appears to be able to sort patients of complicated ASBO, who will require immediate surgical management.

Keywords: Adhesive small bowel obstruction, closed loop obstruction, computed tomography, ischemia, small bowel obstruction

How to cite this article:
Singh SP, Pandey A, Gupta V, Pandey J, Verma R, Mathur AS. Surgery in adhesive small bowel obstruction on basis of computed tomography: A prospective analysis . Niger J Surg Sci 2014;24:36-41

How to cite this URL:
Singh SP, Pandey A, Gupta V, Pandey J, Verma R, Mathur AS. Surgery in adhesive small bowel obstruction on basis of computed tomography: A prospective analysis . Niger J Surg Sci [serial online] 2014 [cited 2023 Apr 1];24:36-41. Available from: https://www.njssjournal.org/text.asp?2014/24/2/36/149601

Introduction

Since the earliest days of abdominal surgery, surgeons have encountered examples of postoperative intestinal obstruction due to adhesion. About 50% of patients of small bowel obstruction (SBO) are due to adhesions, which are almost always related to a prior operation. ^[1]

The treatment regime for adhesive small bowel obstruction (ASBO) is not universal. While successful conservative treatment has been reported, may authors recommend early surgical exploration for all patients with ASBO to avoid excessive morbidity and mortality that may result from delayed operation. ^{[2],[3],[4],[5],[6]}

Contrast-enhanced computed tomography (CECT) has been advocated as a valuable procedure to evaluate ASBO.

The aim of the present study was to evaluate the contribution of CECT in decision making in the management of patients with ASBO due to postoperative adhesions. In this study, we assessed the role of CECT and its advantages over the clinical evaluation and plain radiography in early detection of strangulation and/or closed loop obstruction.

Materials and methods

This prospective study was conducted in Department of Surgery in association with Department of Radiodiagnosis, of the Institute's Hospital from January 2011 to March 2013. It was approved by the hospital ethical committee.

All patients attending the surgical emergency with predominant complaints of pain abdomen, vomiting, constipation, and past history of any abdominal operation and diagnosed clinically as ASBO were included in the study if they met the following criteria:

Patient clinically diagnosed as a case of ASBO with history of clinical symptoms more than 24 h
Patient having history of any abdominal operation more than a month ago.

A patient having history of abdominal operation less than a month ago, patient having associated significant medical problem such as renal failure, hepatic failure, patients with very poor general condition, female patients with pregnancy, and noncooperative patients were excluded from the study.

All patients included in the study were evaluated clinically. X-ray abdomen erect and supine view and CECT was done in all cases. Ultrasonographic abdominal examination and contrast studies were done where ever needed.

Procedure

All the patients underwent CECT using GE Somatom spirit. Serial axial sections of 10 mm thickness were taken from the domes of the diaphragm to the level of the pubic symphysis before and after giving 80-100 ml of iodinated contrast media (ionic/nonionic) intravenously. Five mm thickness sections were taken where ever required.

The CT scan was evaluated by the radiologist independent of the clinical findings for the following:

On CT, the obstruction was confirmed by the presence of dilated bowel loops proximal to the transition zone and collapsed distal small bowel loop or ascending colon
The diagnosis of ASBO was made if no cause of obstruction was identified at the level of transition zone
The level of obstruction was predicted by CT scan
The CT was evaluated for the presence of complication viz. strangulation and closed loop/volvulus.

On CT scan, the diagnosis of strangulation was made when there was:

Reduced the mural enhancement after intravenous (IV) contrast of bowel loop (compared with similarly distended adjacent loop) or presence of at least 2 of the following signs
Presence of ascites
Bowel wall thickness >2 mm
Mesentric congestion
Inter mesenteric fluid.

The diagnosis of closed loop obstructive/volvulus was made when at least one of the following signs were present.

Abnormal distribution of intestine with a fixed radial disposition of dilated bowel loops converging towards the point of torsion
C-shaped/U-shaped loop
Whirl sign
Two adjacent collapsed, round, oval or triangular loop
Beak sign.

Contrast examination was done where ever necessary to differentiate between partial and complete small bowel obstruction.

After the initial clinical examination and CT evaluation, the patients were divided provisionally into two groups:

Simple ASBO - with no clinical, CT signs of strangulation or closed loop/volvulus
Complicated ASBO - the case that had peritoneal signs of irritation (rebound tenderness positive) and/or CT signs of strangulation or closed loop obstruction/volvulus.

Group 1 patients were placed on conservative treatment including nil perorally, IV fluids, and Ryles tube aspiration.

Group 2 patients underwent urgent laparotomy; CT findings were compared with laparotomy findings.

Those patients of simple ASBO (based on clinical or CT evaluation), who did not improve after 72 h of conservative treatment or deteriorated on conservative treatment, underwent delayed laparotomy.

Based on the above study sensitivity and specificity of CT scan to detect complicated ASBO was calculated.

Results

The duration of this study was 2 years. Thirty-two patients, who presented with clinical signs and symptoms of ASBO satisfying the earlier mentioned criteria, were inducted into the study. On CT scan, two patients were diagnosed as malignant obstruction, and they were excluded from the study. Thus, a total of thirty patients were prospectively studied.

The mean age of patients was 37.6 years (range: 15-67 years). The male:female ratio was about 3:1. The duration of symptoms at the time of presentation varied from 24 h to 78 h (mean 46 h). The mean duration of symptoms in simple obstruction was 41 h, while it was 54 h in complicated obstruction. The overall sensitivity of plain radiography for the diagnosis of obstruction was 70%.

Based on CT findings, the level of obstruction was determined in all the 30 patients. It was in jejunum in 10 (33.3%) and ileum in rest 20 (66.7%) patients. The level of obstruction could be confirmed in nine patients, in which laparotomy was performed. It was similar as predicted by CT scan (sensitivity and specificity 100%). In two cases in which oral contrast examination was done, the level of obstruction was found to be at the terminal ileum, both on CT scan and contrast study [Figure 1], [Figure 2], [Figure 3].

Figure 1: Computed tomography scan showing mesenteric congestion and whirl sign suggestive of closed loop obstruction. It was confirmed on laparotomy

Click here to view

Figure 2: Computed tomography scan showing decreased bowel wall enhancement and bowel wall thickening, suggestive of compromised vascularity. It was confirmed on laparotomy

Click here to view

Figure 3: Computed tomography scan showing dilated bowel loops with normal wall enhancement, suggestive of noncomplicated bowel obstruction. It was managed conservatively

Click here to view

Based on CT findings, complicated small bowel obstruction was predicted in ten patients. The features suggestive of strangulation were present in seven out of these ten patients and of closed loop obstruction were present in six cases. Urgent laparotomy was performed in all of them. Remaining 20 patients were placed on conservative treatment initially. The sensitivity and specificity of CT scan to detect strangulation was found to be 100% and 95.8% respectively.

Of 20 patients of simple obstruction, placed initially on conservative treatment, 19 were relieved of obstruction within 72 h. One patient, who did not respond to conservative treatment after 72 h, underwent laparotomy. It turned out to be bowel obstruction at terminal ileum; however, complication of obstruction viz. Strangulation/closed loop were not present.

The diagnostic accuracy of CT scan was excellent having sensitivity of 100%, specificity of 95.3%, and accuracy of 96.7%. In the evaluation of complicated obstruction, reduced mural enhancement, mesenteric congestion, C loop of intestine, whirl sign were highly specific (100%) signs of complication but their sensitivity was low (23-33%). In contrast ascites, mural thickness was more sensitive parameters but with less specificity [Table 1].

Table 1: Value of CT signs for the diagnosis of complicated obstruction

Click here to view

Based on clinical judgment, we diagnosed two out of nine patients of complicated obstruction (presence of signs of peritonism), which were later confirmed by CT findings and laparotomy findings (sensitivity 22.3%, specificity 100%).

Computed tomography diagnosed preoperatively all the nine cases of complicated obstruction. In one case, CT scan predicted complication, but on laparotomy it turned out to be simple obstruction (Sensitivity 100%, Specificity 95.3%) [Table 2].

Table 2: Comparative diagnostic value of clinical CT signs for the diagnosis of complicated obstruction

Click here to view

Discussion

In this study, the decision between initial conservative treatment and urgent operative intervention was arrived after a careful evaluation of the clinical and CT findings of patients. Delayed laparotomy was performed in those patients who showed no improvement even after 72 h of conservative management.

Plain radiographs have been traditionally regarded as an important tool for the diagnosis of small bowel obstruction. The sensitivity of plain radiographs for the diagnosis of small bowl obstruction varies widely in the literature. Plain radiographs in such patients are diagnostic in 50-60%. ^[7] In one study, the reported sensitivity, specificity and accuracy of plain radiographs for diagnosis of small bowel obstruction were 77%, 50%, and 79% respectively. ^[8] In the present study, it was 70%.

Recently, there is an increasing interest to explore the role of CT scan in the management of small bowel obstruction. Various workers have found that CT scan appears to be having high sensitivity, specificity and accuracy in detecting ABSO. ^[9],[10] Certain signs like "C" and "U" configuration, beak sign, and whirl sign etc., have been found in such cases. ^[11] One study found that 57 patients with inconclusive radiographic findings were correctly diagnosed by CT, and it distinguished between small bowel obstruction and ileus in all except one patient. Thus, CT enabled to modify erroneous clinical diagnosis in 21% of patients. ^[12] In present study, CT correctly diagnosed all the 30 patients with intestinal obstruction. Thus, the specificity of the CT scan for diagnosing intestinal obstruction in the present study was 100%.

The reported accuracy of CT scan for the level of obstruction approaches close to that of contrast studies. Suri et al. correctly predicted the level of obstruction in 93% on CT, 70% on ultrasound and 60% on plain films. ^[8] Donckier et al. correctly predicted the level of obstruction in all their 54 patients they studied. They also noted an important correlation between the failure of conservative treatment in cases of simple ASBO and the terminal location of the obstruction. ^[13] In the present study, we predicted the level of obstruction in all the 30 patients. Of these, based on laparotomy findings or contrast study findings, the level of obstruction was confirmed in 13 patients. The level of obstruction was correctly predicted on CT scan in all these 13 cases. Mallo et al. reviewed 15 studies evaluating the diagnostic usefulness of CT scan in identifying patients with SBO, who had bowel ischemia or complete obstruction. ^[14] The sensitivity and specificity of collected data were found to be 83% and 92%.

The cause of obstruction is usually evident on CT scan. If no well-defined cause of obstruction at the site of transition zone could be detected, the diagnosis of adhesions as the cause of obstruction is usually made. Megibow et al. correctly predicted the cause of obstruction in 73% of cases in their series. ^[9] This percentage although not impressive compares favorably with sensitivity of plain films and contrast studies. In a study, CT was found to be superior (87%) to both ultrasound (23%) and plain radiography (7%) in determining the etiology of obstruction. ^[8] In other study, CT was found to be superior to small bowel follow through in detecting the cause of intestinal obstruction. ^[15] In our study, we performed CT scan on 32 patients of suspected ASBO, on CT two patients were diagnosed as case of malignant obstruction and in rest of the patients diagnosis of ASBO was retained. These findings were later confirmed at laparotomy or during the clinical course of the patients.

The results in the present study are comparable with other recent studies for detection of complication. The sensitivity and specificity of 100% and 95.3% for detection of complications in cases of ASBO in present series are comparable with that of other series, where the reported values are 100% and 92% respectively. ^[11] Schwenter et al. showed on multivariate analysis that the following factors predicted the need for bowel resection in patients with bowel obstruction: The presence of more than 500 mL of ascites on CT, reduction of CT bowel wall enhancement, abdominal pain for >4 days; abdominal tenderness with guarding, white blood cell more than 10,000/mL, and C-reactive protein more than 75 mg/L. ^[16] All patients with 4 or more of these variables required resection, whereas only 1 patient who had no positive variables required resection. Zielinski in a somewhat similar type of study found on multivariate analysis, that the independent predictors of the need for operation in ASBO were vomiting, ascites, mesenteric edema on CT, and the lack of the small bowel feces sign. ^[17],[18]

To conclude, CT abdomen appears to be a safe, quick to perform and reliable adjunct to clinical examination in the management of patients with ASBO. It is sensitive, specific and accurate for diagnosis of obstruction, detection of level of obstruction, and the associated complication of obstruction. The clinical examination and plain radiographs, which at times can be misleading, may be supplemented with CT scan in doubtful cases for further planning of increased morbidity and mortality associated with delayed diagnosis of complicated obstruction. CT scan appears to be able to divide patients with ASBO into complicated obstruction who will require immediate surgical management, and simple obstruction who can be safely managed by conservative treatment. The disadvantage with CT is its high cost, but the information that it can provide may be very valuable, and at times, could be life saving for the patient with small bowel obstruction.

In the last, we would like to conclude that the role of the CT scan in ASBO needs to be further evaluated on large scale studies so as to make radiologists and surgeons familiar with information, which CT can provide.

References

1.	Zielinski MD, Bannon MP. Current management of small bowel obstruction. Adv Surg 2011;45:1-29.
2.	Sarr MG, Bulkley GB, Zuidema GD. Preoperative recognition of intestinal strangulation obstruction. Prospective evaluation of diagnostic capability. Am J Surg 1983;145:176-82.
3.	Mucha P Jr. Small intestinal obstruction. Surg Clin North Am 1987;67:597-620.
4.	Tanphiphat C, Chittmittrapap S, Prasopsunti K. Adhesive small bowel obstruction. A review of 321 cases in a Thai hospital. Am J Surg 1987;154:283-7. [PUBMED]
5.	Bizer LS, Liebling RW, Delany HM, Gliedman ML. Small bowel obstruction: The role of nonoperative treatment in simple intestinal obstruction and predictive criteria for strangulation obstruction. Surgery 1981;89:407-13. [PUBMED]
6.	Brolin RE. Partial small bowel obstruction. Surgery 1984;95:145-9. [PUBMED]
7.	Maglinte DD, Howard TJ, Lillemoe KD, Sandrasegaran K, Rex DK. Small-bowel obstruction: State-of-the-art imaging and its role in clinical management. Clin Gastroenterol Hepatol 2008;6:130-9.
8.	Suri S, Gupta S, Sudhakar PJ, Venkataramu NK, Sood B, Wig JD. Comparative evaluation of plain films, ultrasound and CT in the diagnosis of intestinal obstruction. Acta Radiol 1999;40:422-8.
9.	Megibow AJ, Balthazar EJ, Cho KC, Medwid SW, Birnbaum BA, Noz ME. Bowel obstruction: Evaluation with CT. Radiology 1991;180:313-8.
10.	Fukuya T, Hawes DR, Lu CC, Chang PJ, Barloon TJ. CT diagnosis of small-bowel obstruction: Efficacy in 60 patients. AJR Am J Roentgenol 1992;158:765-9.
11.	Scaglione M, Romano S, Pinto F, Flagiello F, Farina R, Acampora C, et al. Helical CT diagnosis of small bowel obstruction in the acute clinical setting. Eur J Radiol 2004;50:15-22.
12.	Taourel PG, Fabre JM, Pradel JA, Seneterre EJ, Megibow AJ, Bruel JM. Value of CT in the diagnosis and management of patients with suspected acute small-bowel obstruction. AJR Am J Roentgenol 1995;165:1187-92.
13.	Donckier V, Closset J, Van Gansbeke D, Zalcman M, Sy M, Houben JJ, et al. Contribution of computed tomography to decision making in the management of adhesive small bowel obstruction. Br J Surg 1998;85:1071-4.
14.	Mallo RD, Salem L, Lalani T, Flum DR. Computed tomography diagnosis of ischemia and complete obstruction in small bowel obstruction: A systematic review. J Gastrointest Surg 2005;9:690-4.
15.	Peck JJ, Milleson T, Phelan J. The role of computed tomography with contrast and small bowel follow-through in management of small bowel obstruction. Am J Surg 1999;177:375-8.
16.	Schwenter F, Poletti PA, Platon A, Perneger T, Morel P, Gervaz P. Clinicoradiological score for predicting the risk of strangulated small bowel obstruction. Br J Surg 2010;97:1119-25.
17.	Zielinski MD, Eiken PW, Bannon MP, Heller SF, Lohse CM, Huebner M, et al. Small bowel obstruction-who needs an operation? A multivariate prediction model. World J Surg 2010;34:910-9.
18.	Zielinski MD, Eiken PW, Heller SF, Lohse CM, Huebner M, Sarr MG, et al. Prospective, observational validation of a multivariate small-bowel obstruction model to predict the need for operative intervention. J Am Coll Surg 2011;212:1068-76.