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

ACR Appropriateness Criteria® Suspected Small-Bowel Obstruction

Small-bowel obstruction is a common cause of abdominal pain and accounts for a significant proportion of hospital admissions. Radiologic imaging plays the key role in the diagnosis and management of small-bowel obstruction as neither patient presentation, the clinical examination, nor laboratory testing are sufficiently sensitive or specific enough to diagnose or guide management. This document focuses on the imaging evaluation of the two most commonly encountered clinical scenarios related to small-bowel obstruction: the acute presentation and the more indolent, low-grade, or intermittent presentation. This document hopes to clarify the appropriate utilization of the many imaging procedures that are available and commonly employed in these clinical settings. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Diagnostic utility of CT for small bowel obstruction: Systematic review and meta-analysis

BACKGROUND

To perform a systematic review and meta-analysis evaluating the diagnostic performance of computed tomography (CT) for small bowel obstruction (SBO), including diagnostic accuracy, ischemia, predicting surgical intervention, etiology and transition point.

METHODS

PubMed/MEDLINE and related databases were searched for research articles published from their inception through August 2018. Findings were pooled using bivariate random-effects and summary receiver operating characteristic curve models. Meta-regression and subgroup analyses were performed to evaluate whether publication year, patient age, enhanced CT, slice thickness and pathogenesis affected classification accuracy.

RESULTS

In total, 45 studies with a total of 4004 patients were included in the analysis. The pooled sensitivity and specificity of CT for SBO were 91% (95% confidence interval [CI]: 84%, 95%) and 89% (95% CI: 81%, 94%), respectively, and there were no differences in the subgroup analyses of age, publication year, enhanced CT and slice thickness. For ischemia, the pooled sensitivity and specificity was 82% (95% CI: 67%, 91%) and 92% (95% CI: 86%, 95%), respectively. No difference was found between enhanced and unenhanced CT based on subgroup analysis; however, high sensitivity was found in adhesive SBO compared with routine causes (96% vs. 78%, P = 0.03). The pooled sensitivity and specificity for predicting surgical intervention were 87% and 73%, respectively. The accuracy for etiology of adhesions, hernia and tumor was 95%, 70% and 82%, respectively. In addition, the pooled sensitivity and specificity for transition point was 92% and 77%, respectively.

CONCLUSIONS

CT has considerable accuracy in diagnosis of SBO, ischemia, predicting surgical intervention, etiology and transition point.

Adult small bowel obstruction

BACKGROUND

Small bowel obstruction (SBO) is a clinical condition that is often initially diagnosed and managed in the emergency department (ED). The high rates of potential complications that are associated with an SBO make it essential for the emergency physician (EP) to make a timely and accurate diagnosis.

OBJECTIVES

The primary objective was to perform a systematic review and meta-analysis of the history, physical examination, and imaging modalities associated with the diagnosis of SBO. The secondary objectives were to identify the prevalence of SBO in prospective ED-based studies of adult abdominal pain and to apply Pauker and Kassirer's threshold approach to clinical decision-making to the diagnosis and management of SBO.

METHODS

MEDLINE, EMBASE, major emergency medicine (EM) textbooks, and the bibliographies of selected articles were scanned for studies that assessed one or more components of the history, physical examination, or diagnostic imaging modalities used for the diagnosis of SBO. The selected articles underwent a quality assessment by two of the authors using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Data used to compile sensitivities and specificities were obtained from these studies and a meta-analysis was performed on those that examined the same historical component, physical examination technique, or diagnostic test. Separate information on the prevalence and management of SBO was used in conjunction with the meta-analysis findings of computed tomography (CT) to determine the test and treatment threshold.

RESULTS

The prevalence of SBO in the ED was determined to be approximately 2% of all patients who present with abdominal pain. Having a previous history of abdominal surgery, constipation, abnormal bowel sounds, and/or abdominal distention on examination were the best history and physical examination predictors of SBO. X-ray was determined to be the least useful imaging modality for the diagnosis of SBO, with a pooled positive likelihood ratio (+LR) of 1.64 (95% confidence interval [CI] = 1.07 to 2.52). On the other hand, CT and magnetic resonance imaging (MRI) were both quite accurate in diagnosing SBO with +LRs of 3.6 (5- to 10-mm slices, 95% CI = 2.3 to 5.4) and 6.77 (95% CI = 2.13 to 21.55), respectively. Although limited to only a select number of studies, the use of ultrasound (US) was determined to be superior to all other imaging modalities, with a +LR of 14.1 (95% CI = 3.57 to 55.66) and a negative likelihood ratio (-LR) of 0.13 (95% CI = 0.08 to 0.20) for formal scans and a +LR of 9.55 (95% CI = 2.16 to 42.21) and a -LR of 0.04 (95% CI = 0.01 to 0.13) for beside scans. Using the CT results of the meta-analysis for the 5- to 10-mm slice subgroup as well as information on intravenous (IV) contrast reactions and nasogastric (NG) intubation management, the pretest probability threshold for further testing was determined to be 1.5%, and the pretest probability threshold for beginning treatment was determined to be 20.7%.

CONCLUSIONS

The potentially useful aspects of the history and physical examination were limited to a history of abdominal surgery, constipation, and the clinical examination findings of abnormal bowel sounds and abdominal distention. CT, MRI, and US are all adequate imaging modalities to make the diagnosis of SBO. Bedside US, which can be performed by EPs, had very good diagnostic accuracy and has the potential to play a larger role in the ED diagnosis of SBO. More ED-focused research into this area will be necessary to bring about this change.

Intra-abdominal adhesions in ultrasound. Part II: The morphology of changes

Despite their frequent appearance, intra-abdominal adhesions are rarely the subject of clinical studies and academic discussions. For many years the operators have been trying to reduce such unfavourable consequences of interventions in the abdominal structures. The aim of this article is to present the possibilities of intra-abdominal adhesion diagnostics by means of ultrasound imaging based on authors’ own experience and information included in pertinent literature. The anatomy and examination technique of the abdominal wall were discussed in Part I of the article. In order to evaluate intraperitoneal adhesions, one should use a convex transducer with the frequency of 3.5–6 MHz. The article provides numerous examples of US images presenting intra-abdominal adhesions, particularly those which appeared after surgical procedures. The significance of determining their localisation and extensiveness prior to a planned surgical treatment is emphasized. Four types of morphological changes in the ultrasound caused by intra-abdominal adhesions are distinguished and described: visceroperitoneal adhesions, intraperitoneal adhesions, adhesive obstructions as well as adhesions between the liver and abdominal wall with a special form of such changes, i.e. hepatic pseudotumour. Its ultrasound features are as follows:

The lesion is localised below the scar in the abdominal wall after their incision.

The lesion is localised in the abdominal part of the liver segments III, IV and V.

With the US beam focus precisely set, the lack of fascia – peritoneum complex may be noticed. An uneven liver outline or its ventral displacement appears.

A hepatic adhesion-related pseudotumour usually has indistinct margins, especially the posterior one, and, gradually, from top to bottom, loses its hypoechogenic nature.

In a respiration test, this liver fragment does not present the sliding movement – a neoplastic tumour rarely shows such an effect. The immobility of the liver is a permanent symptom of subdiaphragmatic abscess which needs to be included in the differentiation process.

In case of doubts, the suspicious liver area may be examined without the consideration of the scar in the abdominal wall.

In the differentiation of visceroperitoneal adhesions, firstly, one needs to exclude the peritoneum infiltration in the course of inflammation and neoplastic spreading, which may be very difficult in patients who have undergone a surgery. Pseudomyxoma peritonei constitutes a source of errors much more rarely.

Evaluation and management of small-bowel obstruction: an Eastern Association for the Surgery of Trauma practice management guideline

BACKGROUND

Small-bowel obstruction (SBO) represents as many as 16% of surgical admissions and more than 300,000 operations annually in the United States. The optimal strategies for the diagnosis and management of SBO continue to evolve secondary to advances in imaging techniques, critical care, and surgical techniques. This updated systematic literature review was developed by the Eastern Association for the Surgery of Trauma to provide up-to-date evidence-based recommendations for SBO.

METHODS

A search of the National Library of Medicine MEDLINE database was performed using PubMed interface for articles published from 2007 to 2011.

RESULTS

The search identified 53 new articles that were then combined with the 131 studies previously reviewed by the 2007 guidelines. The updated guidelines were then presented at the 2012 annual EAST meeting.

CONCLUSION

Level I evidence now exists to recommend the use of computed tomographic scan, especially multidetector computed tomography with multiplanar reconstructions, in the evaluation of patients with SBO because it can provide incremental clinically relevant information over plains films that may lead to changes in management. Patients with evidence of generalized peritonitis, other evidence of clinical deterioration, such as fever, leukocytosis, tachycardia, metabolic acidosis, and continuous pain, or patients with evidence of ischemia on imaging should undergo timely exploration. The remainder of patients can safely undergo initial nonoperative management for both partial and complete SBO. Water-soluble contrast studies should be considered in patients who do not clinically resolve after 48 to 72 hours for both diagnostic and potential therapeutic purposes. Laparoscopic treatment of SBO has been demonstrated to be a viable alternative to laparotomy in selected cases.

Cine-MRI detection of intraabdominal adhesions: correlation with intraoperative findings in 89 consecutive cases

BACKGROUND

This study aimed to evaluate the accuracy of functional cine-MRI in detecting abdominal adhesions.

METHODS

For this study, 89 consecutive patients with adhesion-related complaints after previous abdominal surgery underwent preoperative workup including cine-MRI in transverse and sagittal orientations for a dynamic examination of an induced visceral slide. An abdominal map consisting of nine segments was created to document the location and extent of the adhesion. Cine-MRI and intraoperative findings were correlated.

RESULTS

A total of 59 laparotomies and 30 laparoscopies were performed. Four cases required open surgery due to severe adhesions. The use of cine-MRI scan for the detection of adhesions showed an overall accuracy of 90%, a sensitivity of 93%, and a positive predictive value of 96%. The stronger the adhesions, the more accurate the scan findings. Of 44 patients with second-degree MRI scan findings, 50% had second-degree intraoperative findings. Of 35 patients with third- and fourth-degree adhesions on MRI scans, 74% had exactly the same intraabdominal findings at surgery. The MRI scan showed adhesions located in the small intestines (75%), large intestines (35%), abdominal cavity (42%), and reproductive organs (32%). Intraoperatively, adhesions were found in the small intestines (70%), large intestines (40%), abdominal cavity (42%), and reproductive organs (28%).

CONCLUSIONS

Cine-MRI provides valid preoperative information with respect to extent, location, and strength of intraabdominal adhesions. Cine-MRI is a good alternative for diagnosing abdominal adhesions because objective findings of the scan and intraoperative findings correlate very well with each other.

Functional cine MR imaging for the detection and mapping of intraabdominal adhesions: method and surgical correlation

The purpose of this study was to evaluate the presence and localization of intraabdominal adhesions using functional cine magnetic resonance imaging (MRI) and to correlate the MR findings with intraoperative results. In a retrospective study, patients who had undergone previous abdominal surgery with suspected intraabdominal adhesions were examined. A true fast imaging with steady state precession sequence in transverse/sagittal orientation was used for a section-by-section dynamic depiction of visceral slide on a 1.5-Tesla system. After MRI, all patients underwent anew surgery. A nine-segment abdominal map was used to document the location and type of the adhesions. The intraoperative results were taken as standard of reference. Ninety patients were enrolled. During surgery 71 adhesions were detected, MRI depicted 68 intraabdominal adhesions. The most common type of adhesion in MRI was found between the anterior abdominal wall and small bowel loops (n = 22, 32.5%) and between small bowel loops and pelvic organs (n = 14, 20.6%). Comparing MRI with the intraoperative findings, sensitivity varied between 31 and 75% with a varying specificity between 65 and 92% in the different segments leading to an overall MRI accuracy of 89%. Functional cine MRI proved to be a useful examination technique for the identification of intraabdominal adhesions in patients with acute or chronic pain and corresponding clinical findings providing accurate results. However, no differentiation for symptomatic versus asymptomatic adhesions is possible.

ACR Appropriateness Criteria® on Suspected Small-Bowel Obstruction

With no one generally accepted approach to evaluate patients with suspected small-bowel obstruction (SBO), standard CT has emerged as the preeminent imaging modality and should be considered in the initial evaluation of patients with suspected high-grade SBO. Playing less significant roles in the diagnosis of acute SBO are barium enemas and the small-bowel examination.

Cine magnetic resonance imaging vs high-resolution ultrasonography for detection of adhesions after laparoscopic and open incisional hernia repair: a matched pair pilot analysis

BACKGROUND

Intraabdominal adhesions represent nonspecific complications before or after laparoscopic or open incisional hernia repair. The objective of this matched control pilot study was to display long-term adhesions noninvasively by applying functional cine magnetic resonance (MR) imaging, as compared with applying high-resolution ultrasonography (US).

METHODS

The study group, composed of 17 consecutive patients (12 men and 5 women; mean age, 52 years), underwent laparoscopic intraperitoneal onlay mesh repair using expanded polytetrafluoroethylene (ePTFE) mesh. Their mean body mass index was 30 kg/m(2), and the size of the hernia was 95 cm(2). Another group, matched for age, gender, and type of hernia, was subjected to open abdominal wall repair using the preperitoneal sublay technique with a large-pore, low-weight polypropylene mesh. For cine MR imaging (1.5 T), section-by-section dynamic depiction of induced visceral slide throughout the entire abdomen was achieved by applying transverse or sagittal true fast imaging with steady-state precession sequences. The location and type of adhesions were compared with high-resolution ultrasonography using nine segments of the abdominal map.

RESULTS

The patients subjected to laparoscopic and open incisional hernia repair were examined 16 and 28 months after surgery. The findings showed functional cine MR imaging as superior to high-resolution ultrasonography for assessing the amount of intraabdominal adhesions (n = 53 vs n = 3; p < 0.01). Most frequently, adhesions were seen between small bowel loops and the abdominal wall (n = 22), followed by bowel-to-bowel adhesions (n = 19; p < 0.05). However, adhesions between small bowel loops and the abdominal wall occurred more frequently after open mesh repair (p < 0.05). Furthermore, a strong correlation was observed between patient complaints and findings with cine MR imaging (p < 0.05). Maximum pain correlated significantly with the region of the most distinctive adhesions (p < 0.05).

CONCLUSIONS

Functional cine MR imaging represents a reliable noninvasive technique for detecting long-term adhesions after open and laparoscopic incisional hernia repair. The study results suggest that this approach has distinct advantages over high-resolution ultrasonography.

CT enteroclysis: technique and clinical applications

CT enteroclysis (CTE) has been gradually evolving with technical developments of spiral and multidetector row CT technology. It has nowadays become a well-defined imaging modality for the evaluation of various small bowel disorders. Volume challenge of 2L of enteral contrast agent administrated to the small bowel via a nasojejunal catheter ensures luminal distension, the prerequisite for the detection of mural abnormalities, also facilitating the accurate visualization of intraluminal lesions. CT acquisition is centered on small bowel loops, reconstructed in thin axial slices and completed by multiplanar views. Image analysis is essentially done in cine-mode on work-stations. CTE is of particular diagnostic value in intermediate or advanced stages of Cohn's disease, including the depiction of extraintestinal complications. It has become the imaging modality of choice for the localization and characterization of small bowel tumors. The cause and degree of low-grade small bowel obstruction is more readily analyzed with the technique of CTE than conventional CT. Limitations of CTE concern the assessment of pure intestinal motility disorders, superficial mucosal lesions and arteriovenous malformations of the small bowel, which are not consistently visualized. CTE should be selectively used to answer specific questions of the small bowel. It essentially contributes to the diagnostic quality of modern small bowel imaging, and therefore deserves an established, well-defined place among the other available techniques.

Computed tomography diagnosis of ischemia and complete obstruction in small bowel obstruction: a systematic review

This review was designed to describe the diagnostic performance of computed tomography (CT) in assessing bowel ischemia and complete obstruction in small bowel obstruction (SBO). A MEDLINE search (1966-2004) identified 15 studies dealing with the CT diagnosis of ischemia and complete obstruction in SBO. Ischemia was defined by operative findings, and complete obstruction was defined by enteroclysis or operative findings. Aggregated sensitivity, specificity, and positive and negative predictive values (PPV and NPV) were calculated. Eleven of 15 studies reported on the CT diagnosis of ischemia in SBO based on 743 patients. The aggregated performance characteristics of CT for ischemia in SBO were sensitivity of 83% (range, 63-100%), specificity of 92% (range, 61-100%), PPV of 79% (range, 69-100%), and NPV of 93% (range, 33.3-100%). Seven of 15 studies evaluated the CT classification of complete obstruction based on 408 patients. The aggregated performance characteristics of CT for complete obstruction were sensitivity of 92% (range, 81-100%), specificity of 93% (range, 68-100%), PPV of 91% (range, 84-100%), and NPV of 93% (range, 76-100%). This review demonstrates the high sensitivity of CT for ischemia in the setting of SBO and suggests that a CT scan finding of partial SBO is likely to reflect a clinical condition that will resolve without surgical intervention.

The efficacy of helical CT in the diagnosis of small bowel obstruction

OBJECTIVE

To evaluate the usefulness and reliability of helical computed tomography (CT) for patients with small bowel obstruction.

METHODS AND MATERIAL

Helical CT findings of 41 patients were evaluated prospectively on the basis of the presence and the cause of obstruction, and the presence of strangulation.

RESULTS

In the determination of the cause of the obstruction sensitivity and specificity of CT were 84 and 90%, respectively. Of the 19 patients undergoing surgery, 6 had strangulation and were correctly identified by CT.

CONCLUSION

Helical CT is an accurate method in the detection of small bowel obstruction, especially for evaluating the cause and vascular complications of obstruction.

Recent advances in malignant bowel obstruction: an interface of old and new

Malignant bowel obstruction continues to be a difficult problem for patients with abdominal and pelvic primary tumors and tumors originating in other sites. The main treatment options consist of surgery, stenting, and pharmacotherapy. Despite recent advances, the impact of available treatment modalities on symptom control, longevity, quality of life, and associated health care costs have not been evaluated rigorously. This article reviews the available data and suggests an approach to the management of this challenging patient population.

Modern management of cancer-related intestinal obstruction

Malignant-associated bowel obstruction remains a common and perplexing problem for patients with advanced gynecologic and gastrointestinal malignancies. The ability to locate and define its cause preoperatively has improved with the advent of computed tomography. Initial clinical experience with half-Fourier acquisition single-shot turbo spin-echo magnetic resonance imaging (HASTE MRI) and virtual colonoscopy is exciting. The surgical approach for primary obstructing colon cancer has become more aggressive, with experienced surgical groups doing one-stage procedures. Yet to be defined are guidelines for surgical management of obstructions occurring in the face of recurrent disease. Stent placement for upper and lower bowel obstructions is an option in nonoperable patients. Pharmacologic symptom management for intestinal obstructions consists of an opioid, an anticholinergic, and an antiemetic. Octreotide, either alone or added to the original regimen, will palliate symptoms that are resistant to the three-drug combination.

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.

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.

Detection and mapping of intraabdominal adhesions by using functional cine MR imaging: preliminary results

PURPOSE

To identify and map intraabdominal adhesions by using functional cine magnetic resonance (MR) Imaging.

MATERIALS AND METHODS

Twenty-seven patients suspected of having intraabdominal adhesions were examined. Section-by-section dynamic depiction of induced visceral slide throughout the whole abdomen was achieved by using a transverse or sagittal true fast imaging with steady-state precession sequence. Location and type of diagnosed adhesions were documented by using the nine segments of the abdominal map. These criteria and intraoperative results were compared in 13 patients.

RESULTS

MR images depicted a total of 42 intraabdominal adhesions; 21 (50%) were in the lower abdomen. The most common types of adhesions were located between the ventral abdominal wall and small-bowel loops (n = 10 [24%]) and between adjacent small-bowel loops (n = 9 [21%]). Comparison with the intraoperative results showed a sensitivity of 87.5% and a specificity of 92.5%. MR imaging was most accurate in depicting adhesions to the abdominal wall (15 [94%] of 16) and subperitoneal space (eight [100%] of eight). The presence of adhesions between bowel loops was overestimated.

CONCLUSION

Detection of visceral slide at functional cine MR imaging is easy to perform and represents a well-tolerated and accurate procedure for use in the identification of intraabdominal adhesions in patients with chronic pain and equivocal clinical findings.

Modern management of cancer-related intestinal obstruction

Malignant associated bowel obstruction remains a common and perplexing problem for patients with advanced gynecologic and gastrointestinal malignancies. The ability to locate and define its cause preoperatively has improved with the advent of computed tomography. Initial clinical experience with half-Fourier acquisition single-shot turbo spin-echo magnetic resonance imaging (HASTE MRI) and virtual colonoscopy is exciting. The surgical approach for primary obstructing colon cancer has become more aggressive, with experienced surgical groups doing one-stage procedures. Yet to be defined are guidelines for surgical management of obstructions occurring in the face of recurrent disease. Stent placement for upper and lower bowel obstructions is an option in nonoperable patients. Pharmacologic symptom management for intestinal obstructions consists of an opioid, an anticholinergic, and an anti-emetic. Octreotide, either alone or added to the original regimen, will palliate symptoms that are resistant to the three-drug combination.

Intestinal obstruction

Intestinal obstruction, a disorder that afflicts both children and adults, is associated with significant morbidity. Early recognition and appropriate management can prevent life-threatening complications; however, considerable controversies exist regarding the ideal method of diagnosis and treatment. This article provides a comprehensive overview of risk factors for small and large bowel obstruction. The pathophysiologic process is related to the clinical findings. A summary of diagnostic methods with an evaluation of their relative merit is presented. Preventive, and medical, surgical, and palliative therapies are described, with an emphasis on the actions that an advanced practice nurse can implement.

The role of computed tomography with contrast and small bowel follow-through in management of small bowel obstruction

BACKGROUND

In a significant percentage of patients, radiologic evaluation other than plain abdominal films are required to confirm or exclude the presence of small bowel obstruction.

METHODS

Over a 1-year period, 55 patients had both computed tomography and small bowel follow-through studies. Patients were classified as having (1) paralytic ileus, (2) low-grade obstruction, (3) high-grade obstruction, or (4) complete mechanical obstruction. The gold standard for diagnosis was celiotomy in 42 patients and clinical follow-up in 13 patients.

RESULTS

Thirty-six out of 42 patients had proven intestinal obstruction at the time of celiotomy. Computed tomography identified 32 out of the 36 high-grade and complete mechanical obstructions. Computed tomography was superior to small bowel follow-through in identifying masses, malignancies, and features of strangulation. Small bowel follow-through correctly identified "insignificant obstructions" when contrast reached the cecum within 4 hours in 18 of 19 patients.

CONCLUSIONS

In patients with equivocal findings of small bowel obstruction, computed tomography should be used initially and then small bowel follow-through if computed tomography is not diagnostic. Computed tomography was superior in this study for detecting the cause of the intestinal obstruction and presence of strangulation.