• 
• 

Three Part Question

In an [adult patient presenting with suspected SBO] is [CT] useful in [diagnosis of obstruction and strangulation].

Clinical Scenario

A 65-year-old woman presents to the emergency department with signs and symptoms of SBO. She had previously had an abdominal hysterectomy. Plain abdominal radiograph (AXR) is non-specific. You wonder whether abdominal CT would be useful in the management of a patient with presumptive SBO.

Search Strategy

Medline 1950 to March 2006 using the OVID interface, combined with a manual search of references in papers found.
(exp Intestinal obstruction/AND exp Intestine, Small/AND exp Tomography, X-Ray Computed/) AND ((intestinal adj obstruction) AND CT).mp. limit to (humans and English language).

Search Outcome

A total of 491 papers were found of which 16 were relevant to the topic and one systematic review incorporating 11 of these papers

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Ha et al. 1997 South Korea	84 patients with previous laparotomy presenting with small bowel obstruction (SBO) (41 strangulated) undergoing computed tomography (CT) (intravenous (iv) contrast). Malignant/inflammatory obstruction excluded	Case series	CT diagnosis of strangulation	Sensitivity 85%	Retrospective case series
Suri et al. 1999 India	32 patients presenting with clinical suspicion of intestinal obstruction undergoing AXR, US and CT.	Cohort study	CT diagnosis of, level of and cause of SBO	Diagnosis: sensitivity 93%, specificity 100%, accuracy 94%.Level: sensitivity 93%.Cause: sensitivity 70%	Small numbers
Beall et al. 2002 USA	44 patients with suspected bowel obstruction (28 obstructed) undergoing CT	Cohort study	CT diagnosis of SBO	Accuracy 71%, sensitivity 71%; specificity 71%; positive predictive value (PPV) 83% (n = 21)	Small numbers.
Lazarus et al. 2004 USA	34 patients with CT findings of small bowel obstruction.	Prospective.	Presence of small bowel faeces sign (SBFS). Severity of obstruction. Localisation of obstruction.	SBFS present in 55.9%. Present in 16.6% patients with mild obstruction, 72.7% patients with moderate obstruction and 58.8% patients with high grade obstruction. In 94.7% with SBFS level of obstruction found	Small numbers.
Scaglione et al. 2004 Italy	120 cases of closed loop SBO who had undergone laparotomy within 6 h of CT (iv contrast) and plain abdominal x ray (AXR).	Retrospective analysis	Diagnosis of closed loop SBO and diagnosis of infarction	CT diagnosed closed loop obstruction in 78%. PPV for CT diagnosis of strangulation 100%, negative predictive value (NPV) 73%	Retrospective analysis.
Mallo et al, 2005, USA	11 studies reporting on diagnosis of ischaemia in SBO (743 patients).7 studies reporting on complete/high grade obstruction (408 patients)	Systematic review	Aggregated PPV, NPV, sensitivity and specificity for CT diagnosis of obstruction and infarction	For bowel ischaemia: PPV 79%, NPV 93%, sensitivity 83%, specificity 92%.For bowel obstruction: PPV 92%, NPV 93%, sensitivity 92%, specificity 94%

Comment(s)

Published literature supports the use of CT as a sensitive and specific test for small bowel obstruction. The evidence supports the proposal that CT provides reliable information regarding cause of the obstruction and presence of bowel strangulation.

Clinical Bottom Line

CT is a useful investigation in patients presenting with suspected SBO.

References

1. Ha HK, Kim JS, Lee MS, Lee HJ, Jeong YK, Kim PN, Lee MG, Kim KW, Kim MY, & Auh YH Differentiation of simple and strangulated small-bowel obstructions: usefulness of known CT criteria. Radiology 1997; 204, 507-512
2. 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, 422-428.
3. Beall DP, Fortman BJ, Lawler BC, & Regan F Imaging bowel obstruction: a comparison between fast magnetic resonance imaging and helical computed tomography. Clin Radiol 2002; 57, 719-724.
4. Lazarus DE, Slywotsky C, Bennett GL, Megibow AJ, & Macari M Frequency and relevance of the AJR Am J Roentgenol 2004; 183, 136
5. Scaglione M, Grassi R, Pinto A, Giovine S, Gagliardi N, Stavolo C, & Romano L Positive predictive value and negative predictive value of spiral CT in the diagnosis of closed loop obstruction Radiol Med (Torino) 2004; 107, 69-77.
6. Mallo RD, Salem L, Lalani T, et al. Computed tomography diagnosis of ischemia and complete obstruction in small bowel obstruction: a systematic review. J Gastrointest Surg 2005;9:690–4.