CT diagnosis of small-bowel obstruction: efficacy in 60 patients

The utility of computed tomography in acute small bowel obstruction

Small bowel obstruction is a significant cause of acute surgical admissions. Surgeons are tending to favour an initial trial of conservative management. Due to the unreliability of clinical signs to predict accurately those patients requiring early intervention there is an increasing tendency to utilize imaging investigations, particularly computed tomography (CT), to help define the severity, cause and complications of acute small bowel obstruction. The aim of this pictorial review is to demonstrate the contribution CT can make to the management of these patients. Burkill, G. J. C., Bell, J. R. G. & Healy, J. C. (2001). Clinical Radiology56, 350-359.

Helical CT in the diagnosis of small bowel obstruction

With recent technologic developments, the role of computed tomography (CT) in the diagnosis of bowel obstruction has expanded. CT is recommended when clinical and initial radiographic findings remain indeterminate or strangulation is suspected. This modality clearly demonstrates pathologic processes involving the bowel wall as well as the mesentery, mesenteric vessels, and peritoneal cavity. CT should be performed with intravenous injection of contrast material, and use of thin sections is recommended to evaluate a particular region of interest. CT is reported to have a sensitivity of 78%-100% for the detection of complete or high-grade small bowel obstruction but may not allow accurate diagnosis in cases involving incomplete obstruction. In such cases, the use of adjunct enteroclysis is indicated. Furthermore, multiplanar reformatted imaging may help identify the site, level, and cause of obstruction when axial CT findings are indeterminate. CT can also demonstrate findings that indicate the presence of closed-loop obstruction or strangulation, both of which necessitate emergency exploratory laparotomy. Unfortunately, these pathologic conditions may be missed, and patients with suspected severe obstruction or bowel ischemia in whom CT and clinical findings are widely disparate must also undergo laparotomy. In general, however, CT allows appropriate and timely management of these emergency cases.

Bowel obstruction following liver transplantation: clinical and ct findings in 48 cases with emphasis on internal hernia

PURPOSE

To review the incidence, cause, and radiologic findings of bowel obstruction in patients who have undergone orthotopic liver transplantation (OLT).

MATERIALS AND METHODS

Retrospective review of 4,001 cases of OLT revealed 48 cases of bowel obstruction in 44 patients. Seventeen computed tomographic (CT) scans and seven barium-enhanced radiographs were reviewed to determine level and cause. Surgical proof was available in 45 cases, while three had characteristic clinical and radiographic features.

RESULTS

Adhesions caused the obstruction in 19 cases in 16 patients; three had bowel ischemia. Internal hernias caused obstruction in 18 patients; all obstructions were transmesenteric or retroanastomotic and occurred with choledochoenteric anastomosis. Seven patients had volvulus; four had bowel ischemia. CT signs of internal hernia included mesenteric vascular abnormalities and clusters of dilated small-bowel segments that displaced the colon away from the abdominal wall. Prospective diagnosis of internal hernia was made in only one case. Incisional or inguinal hernia caused obstruction in seven patients; CT was used just once. Four patients had neoplastic bowel obstruction, three due to posttransplantation lymphoproliferative disorder and one due to colon carcinoma.

CONCLUSION

Liver transplantation was complicated by bowel obstruction in 48 (1.2%) of 4,001 cases. While adhesions and incisional hernias are common and well recognized, other causes are more challenging to diagnose. The CT findings reported here may allow more accurate diagnosis of internal hernia.

Abdominal radiography findings in small-bowel obstruction: relevance to triage for additional diagnostic imaging

OBJECTIVE

Our aim was to determine which findings on abdominal radiography are relevant for distinguishing complete or high-grade partial small-bowel obstruction from low-grade partial or no small-bowel obstruction.

MATERIALS AND METHODS

Admitting abdominal radiographs with the patients in the supine and upright positions were scored for 25 different findings in 81 patients with clinically suspected small-bowel obstruction. Forty-one patients had complete or high-grade partial small-bowel obstruction, and 40 had low-grade partial small-bowel obstruction or no obstruction as determined by enteroclysis examination. Abdominal radiography findings were subjected to statistical analysis for correlation with degree of obstruction.

RESULTS

Of 12 radiographic findings strongly associated (p < 0.05) with the severity of obstruction, two findings were found to be the most significant (p < or = 0.0003) and predictive of a higher grade small-bowel obstruction: the presence of air-fluid levels of differential height in the same small-bowel loop and the presence of a mean air-fluid level width greater than or equal to 25 mm on upright abdominal radiographs.

CONCLUSION

When both critical findings are present, the degree of small-bowel obstruction is likely high-grade or complete. When both signs are absent, small-bowel obstruction is likely low-grade or nonexistent. Upright abdominal radiographs are important in the examination of patients with suspected small-bowel obstruction and may contribute to the imaging triage of these patients.

Small-bowel obstruction: optimizing radiologic investigation and nonsurgical management

Small-bowel obstruction is an old and common problem. Like most illnesses, its diagnosis and treatment continue to evolve. The radiologic approach to the investigation of small-bowel obstruction and the timing of surgical intervention have undergone considerable changes during the past decade. In this review, the authors analyze the recently described radiologic techniques used in the examination of patients with suspected mechanical small-bowel obstruction, revisit the controversy of the short versus long decompression tube, and provide insights on how to optimize the radiologic investigation and nonsurgical management of small-bowel obstruction.

Helical CT signs in the diagnosis of intestinal ischemia in small-bowel obstruction

OBJECTIVE

The purpose of our study was to determine prospectively the value of helical CT and of various signs of ischemia in the context of acute bowel obstruction.

SUBJECTS AND METHODS

All patients seen over a 3-year period with a CT diagnosis of small-bowel obstruction were included. There were 144 examinations in 142 patients. Images were interpreted prospectively with consensus by a fellow and an experienced gastrointestinal radiologist. Attention was focused on the presence of the following signs of strangulation and ischemia: reduced enhancement of the small-bowel wall, mural thickening, mesenteric fluid, congestion of small mesenteric veins, and ascites. A diagnosis of ischemia was made if enhancement of the bowel wall was reduced or if at least two of the other signs were found. Results were correlated with surgical findings in 73 cases and clinical follow-up in 71 cases.

RESULTS

A diagnosis of ischemia was made at surgery in 24 patients. CT diagnosis was correct in 23 patients (96% sensitivity). There were nine false-positive diagnoses (93% specificity). The negative predictive value of CT was 99%. Reduced enhancement of the bowel wall had a sensitivity of 48% and specificity of 100%, mural thickening had a sensitivity of 38% and specificity of 78%, mesenteric fluid had a sensitivity of 88% and specificity of 90%, congestion of mesenteric veins had a sensitivity of 58% and specificity of 79%, and ascites had a sensitivity of 75% and specificity of 76%.

CONCLUSION

Helical CT is a highly sensitive method to diagnose or rule out intestinal ischemia in the context of acute small-bowel obstruction.

CT of patients with right-sided colon cancer and distal ileal thickening

OBJECTIVE

The purpose of this study was to analyze the incidence and primary causes of distal ileal wall thickening in 131 patients with right-sided colon cancer.

SUBJECTS AND METHODS

During a 2-year period, 131 patients underwent surgical resection for right-sided colon cancer. Of these patients, we analyzed 13 who had distal ileal wall thickening on CT before surgery and also had the cause determined at pathology. CT findings were analyzed with regard to the morphologic features of colonic tumors, bowel wall involvement patterns of the distal ileum, and changes in the pericolic space.

RESULTS

Distal ileal wall thickening occurred in 13 (10%) of the 131 patients who had right-sided colon cancer. Three patients had polypoid colon cancer, whereas the other 10 had infiltrative colon cancer. The mean thickness of the involved colonic segments was 1.6 cm (range, 1.0-2.2 cm) with a mean length of 5.2 cm (range, 2.5-10.0 cm). Pericolic infiltration was mild in six patients and moderate in four patients. The mean length and thickness of the affected ileal segments were 3.2 cm (range, 1.5-6.0 cm) and 1.1 cm (range, 0.7-2.0 cm), respectively. On histopathologic examination, neoplastic processes involved the distal ileum in nine (69%) of the 13 patients. This involvement was caused by either direct tumor invasion in seven patients or lymphatic spread in two. In four patients (31%), nonneoplastic processes with edema and congestion involved the distal ileum.

CONCLUSION

The distal ileum may be abnormally thickened in about 10% of patients with right-sided colon cancer; this thickening results from tumor extension (69%) or a nontumorous process (31%).

Small-bowel disease: comparison of MR enteroclysis images with conventional enteroclysis and surgical findings

PURPOSE

To investigate if magnetic resonance (MR) enteroclysis can be performed routinely and to compare MR enteroclysis findings with those of conventional enteroclysis or surgery.

MATERIALS AND METHODS

MR enteroclysis was prospectively performed in 30 patients with symptoms of inflammatory bowel disease or small-bowel obstruction (SBO). A methylcellulose-water solution was used to distend the small bowel. To monitor dynamic changes in the small bowel, a single-shot fast spin-echo T2-weighted sequence was applied. For morphologic assessment, breath-hold T2-weighted fast spin-echo and coronal T1-weighted gradient-recalled-echo MR images were obtained without and with gadolinium enhancement. Image quality and degree of small-bowel distention were graded. MR imaging findings and degree of SBO were compared with findings at conventional enteroclysis (n = 25) or surgery (n = 5).

RESULTS

MR enteroclysis was well tolerated and provided adequate image quality and sufficient small-bowel distention. SBO grade based on MR enteroclysis images (n = 10) was identical to that based on conventional enteroclysis images (n = 6) or surgical findings (n = 4). There was exact agreement between MR enteroclysis and retrospective findings in all five patients who underwent surgery, and MR findings were identical to those at enteroclysis in 18 patients, superior in six patients, and inferior in one patient.

CONCLUSION

MR enteroclysis can be performed routinely with adequate image quality and sufficient small-bowel distention. The functional information provided by MR enteroclysis is identical to that provided at conventional enteroclysis.

Tailored helical CT evaluation of acute abdomen

Helical computed tomography (CT) allows rapid, cost-effective evaluation of patients with acute abdominal pain. Tailoring the examination to the working clinical diagnosis by optimizing constituent factors (eg, timing of acquisition, contrast material used, means and rate of contrast material administration, collimation, pitch) can markedly improve diagnostic accuracy. Rapid (>/=3 mL/sec) intravenous injection of contrast material is required for optimal assessment of acute pancreatitis, ischemic bowel, aortic aneurysm, and aortic dissection. Narrow collimation and small reconstruction intervals can help detect calculi in the biliary system and genitourinary tract. Tailored helical CT in patients with acute pyelonephritis usually involves several acquisitions through the kidneys during various phases of renal enhancement. In patients with suspected renal infarction, CT protocol must include an acquisition during the corticomedullary phase. Helical CT with 5-mm collimation through the lower abdomen and pelvis is used to evaluate patients with suspected diverticulitis. Use of both oral and intravenous contrast material can help localize small bowel perforation and characterize related complications. Tailored helical CT for assessment of abdominal hemorrhage consists of initial unenhanced CT followed by optional contrast material-enhanced CT. Clear communication between the radiologist, the patient, and the referring physician is essential for narrowing the differential diagnosis into a working diagnosis prior to helical CT.

Targeted helical CT of the acute abdomen: appendicitis, diverticulitis, and small bowel obstruction

CT, especially helical CT, provides a fast and reliable modality for evaluation of the patient presenting with acute abdominal pain. Helical CT can provide an accurate diagnosis in the majority of patients and has found great utility in the evaluation of acute gastrointestinal emergencies, including acute appendicitis, diverticulitis, and small bowel obstruction. This article reviews proper helical CT technique, diagnostic imaging findings, and pitfalls of interpretation in evaluation of these acute abdominal disorders.

Usefulness of MR imaging for diseases of the small intestine: comparison with CT

OBJECTIVE

To evaluate the usefulness of MR imaging for diseases of the small intestine, emphasizing a comparison with CT.

MATERIALS AND METHODS

Thirty-four patients who underwent both CT and MR imaging using FLASH 2D and HASTE sequences were analyzed. All patients had various small bowel diseases with variable association of peritoneal lesions. We compared the detectabilities of CT and MR imaging using different MR pulse sequences. The capability for analyzing the characteristics of small intestinal disease was also compared.

RESULTS

MR imaging was nearly equal to CT for detecting intraluminal or peritoneal masses, lesions in the bowel and mesentery, and small bowel obstruction, but was definitely inferior for detecting omental lesions. The most successful MR imaging sequence was HASTE for demonstrating bowel wall thickening, coronal FLASH 2D for mesenteric lesions, and axial FLASH 2D for omental lesions. MR imaging yielded greater information than CT in six of 12 inflammatory bowel diseases, while it was equal to CT in six of seven neoplasms and inferior in five of seven mesenteric ischemia. In determining the primary causes of 15 intestinal obstructions, MR imaging was correct in 11 (73%) and CT in nine (60%) patients.

CONCLUSION

MR imaging can serve as an alternative diagnostic tool for patients with suspected inflammatory bowel disease, small intestinal neoplasm or obstruction.

The Utility and Reliability of Computed Tomography Scan in the Diagnosis of Small Bowel Obstruction

Accurate diagnosis and treatment of small bowel obstruction (SBO) is critical to prevent complications and reduce costs. The purpose of the current study was to evaluate the evolving role of CT scan for patients with suspected SBO and compare its sensitivity and specificity with plain abdominal films. We identified 108 patients over a 1-year period with an admission or discharge diagnosis of SBO. Five patients treated on a clinical basis without radiographic imaging and those with indeterminate films were excluded from analysis. CT and radiograph reports were compared with operative findings or clinical course in 103 patients. By the clinical course, 66 of the patients had a partial or complete SBO. Plain film radiography correctly established the diagnosis of SBO in 50 of 66 patients (sensitivity, 75%). Nine of 17 plain films were true negatives (specificity, 53%). CT was able to correctly identify partial or complete SBO in 35 of 38 patients (sensitivity, 92%) and correctly identified the lack of obstruction in 8 of 13 patients (specificity, 71%). These data document that plain films are a less sensitive and less specific method of diagnosing SBO and confirm that the use of CT scan is a valuable modality. CT scan should be considered for use as the primary test for patients with suspected SBO.

Strangulation of small bowel due to Meckel diverticulum: CT findings

We report an unusual case of small bowel strangulation due to long Meckel diverticulum. CT demonstration of the bundle-like segment contiguous with the distended fluid-filled loops of bowel contributed to the prompt preoperative diagnosis.

Plain films and cross-sectional imaging for acute abdominal pain: unresolved issues

The evaluation of acute abdominal pain in its varied presentations has been greatly benefitted by the application of cross-sectional imaging studies. Yet this advance has engendered controversy as well as enthusiasm. One area of contention is the appropriate continued use of basic radiography in the face of the demonstrated capabilities of CT for the diagnosis of both pneumoperitoneum and obstruction. A second concern that must come to the fore is the radiation risk attendant on the universal use of CT for most acute abdominal presentations. A third area needing further discussion is the competition between CT and ultrasonography. Here the debate about decision making should not be one of shrill advocacy, but must be broadened and deepened to consider appropriate imaging resource utilization for individuals of differing habits and habitus.

Computed tomography compared with small bowel enema in clinically equivocal intestinal obstruction

OBJECTIVE

To compare the findings in computed tomography (CT) and small bowel enema (SBE) in clinically equivocal small bowel obstruction in order to identify the reasons for the limitation of CT evaluation.

SUBJECT AND METHOD

Over a period of 5 years, 49 patients who had both CT and SBE within a period of 1 week were analysed. The findings at SBE were categorized into partial low-grade, partial high-grade and complete obstruction and compared with the CT findings. A critical analysis of the CT false-negative cases was made. The predictive values for the determination of the presence of obstruction in CT were also obtained.

RESULTS

Forty-three out of the 49 patients had proven intestinal obstruction. CT correctly identified 34 cases including 19 of 20 with partial high-grade obstruction, two with complete obstruction and 13 out of 21 cases of partial low-grade obstruction. Among those cases with low-grade obstruction cases with complex or long segment narrowing or with masses were correctly identified while six patients with short stenotic segment due to various causes were not. CT also had two false-positive findings of obstruction in patients with mesenteric infarction. SBE had neither false positive nor false negative. The sensitivity, specificity, positive predictive value and negative predictive values for CT were 83%, 67%, 94% and 36%, respectively. Abrupt transition from dilated to collapsed loops in CT were caused by various intraluminal lesions apart from adhesions. CT was superior to SBE in showing extraluminal masses, revealing abscesses, tuberculous lesions and malignancy anterior adhesions as well as features of strangulation.

CONCLUSION

Apart from degree of obstruction and the presence of masses, the length of the stenotic part also affected CT detection. Abrupt change from dilated to collapsed segment could be due to various transmural and intraluminal lesions although adhesions was the commonest lesion. While SBE is more accurate in identifying the presence and location of obstruction, CT is superior for detection of the cause of small bowel obstruction and also for the presence of strangulation. In places where CT is more widely used for intestinal obstruction, SBE evaluation could be prudently considered in CT negative cases of clinically equivocal intestinal obstruction.

Acute mesenteric ischemia. CT and plain radiographic analysis of 26 cases

The purpose of this study was to assess the computed tomography (CT) and plain radiographic findings of acute mesenteric ischemia, in an effort to elucidate its poor prognostic signs. The study group consisted of 26 cases with pathologically or angiographically proven mesenteric ischemia. The pathologically proven longitudinal extent of the bowel ischemia was graded using six degrees, and correlated with the radiographic findings. The mortality of the patients depended primarily on the extent of infarctions and the age of the patient. Patients with bowel dilation or abnormal gas in the bowel wall or portal system were prone to have wider extents of ischemia.

Advances in imaging of the acute abdomen

Over the last 10 years, the most significant advancement in imaging of the acute abdomen has been the development of helical CT imaging. Rapid breath-hold imaging and improved intravascular opacification have enabled radiologists to obtain volumetric data that can be viewed in smaller slice increments. Helical data can also be analyzed utilizing multiplanar and three-dimensional techniques. With its proven ability to diagnose a wide variety of conditions, CT remains the diagnostic modality of choice for imaging the surgical abdomen. There have been considerable improvements in image resolution in US with improvements in transducer technology. Ultrasonography often serves as the first study in evaluating the pediatric or female patient with right lower quadrant or pelvic pain. Computed tomography may be necessary if US is not diagnostic. Despite these technical advances, plain film radiography should be the first imaging study for suspected cases of bowel perforation or obstruction. Magnetic resonance imaging continues to evolve, with improvements in hardware and software design that allow for faster imaging, but current levels of availability in the acute setting preclude its wider use. Whereas further imaging is not necessary for patients presenting with classic signs and symptoms of various acute abdominal diseases, the atypical patient often requires careful diagnostic imaging. Close consultation between the radiologist and surgeon leads to studies appropriately tailored to meet the diagnostic challenge at hand.

Case report. Small bowel obstruction due to phytobezoar formation within Meckel diverticulum: CT findings

Intestinal obstruction due to a phytobezoar within a Meckel diverticulum is exceedingly rare, with only seven reported cases in the surgical literature. The most important precipitating factor is the ingestion of agents high in fiber and cellulose. Small bowel obstruction in all but one case was due to retrograde propagation of the bezoar into the small bowel lumen. We report the clinical and CT findings in such a patient following a vegetarian diet.

Computed tomographic enteroclysis: one methodology

RATIONALE AND OBJECTIVES

Computed tomography (CT) is limited in the assessment of partial small bowel obstruction (SBO). Enteroclysis is preferred but gives little direct information about the bowel wall, mesentery, or remote findings. Preliminary results of a combined CT enteroclysis (CT-E) methodology are reported.

METHODS

Forty-eight patients with suspected partial SBO underwent a water soluble contrast enteroclysis followed immediately by CT. Pump rates at fluoroscopy and CT were 75 to 100 cc/min unless a high-grade obstruction was encountered at fluoroscopy. Shrake's criteria for complete, high-grade or low-grade partial SBO were used.

RESULTS

The calculated dose per patient was 27 rad for CT-E as opposed to 32 rad with traditional enteroclysis. Site specific sensitivity and specificity for low-grade partial SBO, were 82.1% and 87.5%. One death was encountered in a patient with diffuse abdominal metastatic disease and complete obstruction. This was caused by vomiting and aspiration secondary to tube placement alone, CT-enteroclysis having been aborted.

CONCLUSIONS

Computed tomographic enteroclysis is a diagnostic option for evaluation of low-grade partial SBOs. Pitfalls with this technique are encountered in decompressed torsions and hernias.

The CT small bowel faeces sign: description and clinical significance

OBJECTIVE

To describe a new CT sign of the GI tract: the small bowel faeces sign, and discuss its significance.

METHODS

The small bowel faeces sign consists of gas bubbles mixed with particulate matter in dilated segments of small bowel. This was a retrospective study of 22 patients demonstrating this sign from 1989 to 1993. Final diagnosis was established by surgical, medical or laboratory findings. To determine the prevalence of the sign, the CT examination of 120 consecutive separate control patients were evaluated.

RESULTS

All 22 of the patients demonstrating this sign required hospitalization with surgical or medical intervention. Eighteen of 22 had mechanical small bowel obstruction. The remaining four patients had other abnormalities of small bowel to account for the finding on CT. Twelve of the 22 patients were treated with surgery and the remaining 10 patients were treated with nasogastric tubes (n = 6) or other medical therapy (n = 4). None of the 120 control patients demonstrated the sign.

CONCLUSION

The presence of gas and particulate material resembling faeces in a dilated segment of small bowel on CT is abnormal. Most (18/22; 82%) patients with this sign had small bowel obstruction.

Role of CT in the acute nontraumatic abdomen

The diagnostic workup of the acute abdomen always begins with a precise clinical history, a complete physical examination, and careful reading of plain films. Commonly performed additional imaging studies include contrast examination and, more recently, ultrasound. CT offers the advantage of allowing a comprehensive diagnostic evaluation of both solid and hollow viscera in neoplastic as well as in inflammatory and vascular disorders.

Role of CT in evaluating patients with small-bowel obstruction

The accurate and rapid diagnosis of acute small-bowel obstruction has troubled surgeons and radiologists for more than a century. With the advent of CT, solving the problem is now a possibility. CT can accurately diagnose obstruction, determine the likely cause and location, and even suggest whether there is associated bowel ischemia or strangulation.

CT in the early detection of strangulation in intestinal obstruction

The role of CT in evaluating the gastrointestinal tract has increased recently because CT demonstrates pathological conditions involving the bowels, mesenteric vessels, and peritoneal cavity well. In patients who have an intestinal obstruction, the observation of both bowel loop configuration and mesenteric vessels on CT is the key to identifying the site and cause of obstruction and determining the absence or presence of intestinal strangulation. Although many clinical and radiological findings reported in the literature are not seen in the early stages of intestinal strangulation, CT might assist in its early detection. This article reviews the clinical, pathophysiological, and radiological aspects of strangulating obstruction with emphasis on the role of CT in its early diagnosis.

Computed tomography in acute small bowel obstruction

The abdominal computed tomograms of 28 patients with a clinical diagnosis of acute small bowel obstruction were reviewed. Computed tomography accurately identified the presence, severity and level of obstruction. Signs such as angulated bowel loops and adjacent streaks within the mesentery at points of luminal calibre change were recognized in 69% of cases with adhesive obstruction. Computed tomography may reveal non-adhesive causes and is the modality of choice for investigating patients with higher grades of bowel obstruction where early surgical intervention is contemplated.

Nasointestinal tube for decompression or enteroclysis: experience with 150 patients

The initial clinical experience with the use of a triple lumen long tube designed for gastrointestinal decompression and enteroclysis is reported in 150 patients. Based on clinical observations, this tube is effective in suctioning retained gastric and intestinal fluid but requires frequent irrigation of the sump port for effective decompression of distended small bowel. In all patients with a preexisting nasogastric tube, the replacement by the decompression/enteroclysis tube was considered more comfortable by the patients. Successful placement of the tube in the jejunum was achieved in 147 of 150 consecutive patients on the initial attempt. The use of this tube obviates dual intubations for decompression and enteroclysis, the attendant discomfort on the patient, and it expedites subsequent performance of enteroclysis if needed. The complications reported with other long intestinal tubes were not observed with this device.