Imaging Pearls ❯ Small Bowel ❯ Small Bowel Obstruction
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- “The small-bowel feces sign is a finding that can be observed on computed tomographic (CT) scans of the abdomen. It is defined by the presence of particulate (colonlike) feculent matter mingled with gas bubbles in the lumen of dilated loops of the small intestine). The particulate feculent material mingled with gas bubbles seen in the small-bowel feces sign resembles the appearance of stool in the colon on CT scans. It is the result of delayed intestinal transit and is believed to be caused by incompletely digested food, bacterial overgrowth, or increased water absorption of the distal small-bowel contents due to obstruction.”
The small-bowel feces sign.
Fuchsjäger MH.
Radiology. 2002 Nov;225(2):378-9. doi: 10.1148/radiol.2252010976. PMID: 12409569. - “The small-bowel feces sign has been described as a finding indicative of SBO or another severe small-bowel abnormality(ie, metabolic or infectious disease). Bowel obstructionaccounts for approximately 20% of acute abdominal surgical interventions. In 60%– 80% of cases of intestinal obstruc-tion, the small bowel is involved. SBO occurs wheneverintrinsic or extrinsic blocking of the normal flow of small-bowel contents is present.”
The small-bowel feces sign.
Fuchsjäger MH.
Radiology. 2002 Nov;225(2):378-9. doi: 10.1148/radiol.2252010976. PMID: 12409569.
- “In conclusion, when applied to CTs obtained to assess suspected BO, a model combining supervised 2D and 3D convolutional neural networks effectively identified those CTs showing evidence of BO. Leveraging this model has the potential to enhance the triage process for abdominal scans and therefore to appropriate patient management, notably during on-call hours. Furthermore, this approach acts as the first step in automating the selection of patients with mechanical small BO and assessing the severity of CT signs that indicate the need for surgical management.”
Deep learning for automatic bowel-obstruction identification on abdominal CT
Quentin Vanderbecq et al.
European Radiology https://doi.org/10.1007/s00330-024-10657 - Rationale and objectives: Automated evaluation of abdominal computed tomography (CT) scans should help radiologists manage their massive workloads, thereby leading to earlier diagnoses and better patient outcomes. Our objective was to develop a machine-learning model capable of reliably identifying suspected bowel obstruction (BO) on abdominal CT.
Conclusion: The 3D mixed convolutional neural network developed here shows great potential for the automated binary classification (BO yes/no) of abdominal CT scans from patients with suspected BO.
Clinical relevance statement: The 3D mixed CNN automates bowel obstruction classification, potentially automating patient selection and CT prioritization, leading to an enhanced radiologist workflow.
Deep learning for automatic bowel-obstruction identification on abdominal CT
Quentin Vanderbecq et al.
European Radiology https://doi.org/10.1007/s00330-024-10657 - Key Points
• Bowel obstruction’s rising incidence strains radiologists. AI can aid urgent CT readings.
• Employed 1345 CT scans, neural networks for bowel obstruction detection, achieving high accuracy and sensitivity on external testing.
• 3D mixed CNN automates CT reading prioritization effectively and speeds up bowel obstruction diagnosis.
Deep learning for automatic bowel-obstruction identification on abdominal CT
Quentin Vanderbecq et al.
European Radiology https://doi.org/10.1007/s00330-024-10657 - “In conclusion, when applied to CTs obtained to assess suspected BO, a model combining supervised 2D and 3D convolutional neural networks effectively identified those CTs showing evidence of BO. Leveraging this model has the potential to enhance the triage process for abdominal scans and therefore to appropriate patient management, notably during on-call hours. Furthermore, this approach acts as the first step in automating the selection of patients with mechanical small BO and assessing the severity of CT signs that indicate the need for surgical management.”
Deep learning for automatic bowel-obstruction identification on abdominal CT
Quentin Vanderbecq et al.
European Radiology https://doi.org/10.1007/s00330-024-10657
- Bowel obstruction in oncology patients can happen directly as a result of the tumor (malignant bowel obstruction) or as a sequel of post-operative adhesion, mesenteric defect or post radiation changes. Patients with bowel obstruction present with abdominal pain, nausea and vomiting, abdominal distention, and decreased stool and flatus. 5-15% of intestinal obstructions have been associated with cancer. Bowel obstruction complicates approximately 10–30% of colorectal cancer (leading cause of malignant bowel obstruction) and 20–50% of ovarian cancers. Small bowel obstruction happens more frequently than large bowel obstruction. However, unlike the case for large bowel, primary neoplasms are less likely to be the cause of small bowel obstruction. Small bowel obstruction is more often due to adhesions and inflammations. Even in cases with malignant obstruction, the etiology is mostly peritoneal metastases from breast cancer, melanoma or lung cancer rather than primary small bowel neoplasms.
Imaging of abdominopelvic oncologic emergencies.
Pooyan A, Mansoori B, Wang C.
Abdom Radiol (NY). 2023 Nov 28. doi: 10.1007/s00261-023-04112-8. Epub - “Intestinal internal hernias can develop after surgery. Internal hernia can occur with or without obstruction and strangulation signs. A helpful strategy to aid diagnosis is to follow the mesenteric vein branching and noting any caliber change. A swirling pattern may or may not be present. In general, the presence of angiocentric mesenteric edema and prominent lymph nodes raises concern for an internal hernia. If the internal hernia is accompanied by obstruction, imaging findings such as decreased bowel wall enhancement, pneumatosis, and increased wall attenuation on noncontrast CT due to intramural hemorrhage are highly suspicious for bowel ischemia. If there is venous occlusion this will result in outflow obstruction resulting in elevated intramural hydrostatic pressure and edema in the submucosal layer between the enhancing mucosa and muscularis propria resulting in bowel wall thickening and the “target” or “halo” sign.”
Imaging of abdominopelvic oncologic emergencies.
Pooyan A, Mansoori B, Wang C.
Abdom Radiol (NY). 2023 Nov 28. doi: 10.1007/s00261-023-04112-8. Epub - “Abdominopelvic oncologic emergencies encompass a wide range of pathologies that are best categorized in four distinct groups including vascular, bowel, hepatopancreaticobiliary, and bone-related complications. These complications would either happen as a result of the disease itself or are caused by cancer treatment. Familiarity with pathophysiology, natural course of the disease, and imaging features of each entity is crucial for radiologists. This knowledge helps to make timely diagnosis, recommend appropriate next steps, and ultimately improve patient outcome.”
Imaging of abdominopelvic oncologic emergencies.
Pooyan A, Mansoori B, Wang C.
Abdom Radiol (NY). 2023 Nov 28. doi: 10.1007/s00261-023-04112-8. Epub
- Approximately 20% to 30% of patients hospitalized with small bowel obstruction (SBO) fail nonoperative treatment.1,2 Rapidly identifying patients requiring urgent surgical intervention is critical.3 Currently, computed tomography (CT) is the criterion standard for diagnosing SBO management. However, practice variation exists due to a lack of definitive operative radiographic findings for SBO.We compared the ability of clinical features alone with that of clinical features combined with CT findings to estimate the need for surgical SBO management.
Clinical Features vs CT Findings to Estimate Need for Surgery in Small Bowel Obstruction
Sara Schulwolf et al.
JAMA Network Open. 2023;6(11):e2341376. doi:10.1001/jamanetworkopen.2023.41376 - “In this large multicenter comparative effectiveness research, a model combining clinical features and CT variables achieved equivalent performance in estimating the need for surgical SBO management within 24 or 48 hours of presentation as clinical variables alone. Furthermore, clinical features alone demonstrated greater accuracy in estimating the need for operative management at all times. These findings suggest that clinical features alone may be sufficient to identify the need for surgery in patients with SBO. Currently, more than 140 000 CT scans are performed on patients with suspected SBO annually. Our findings suggest that clinical features may risk-stratify and identify patients who require urgent surgical intervention.”
Clinical Features vs CT Findings to Estimate Need for Surgery in Small Bowel Obstruction
Sara Schulwolf et al.
JAMA Network Open. 2023;6(11):e2341376. doi:10.1001/jamanetworkopen.2023.41376 - “Alternative imaging modalities with lower cost and no radiation, such as point-of-care ultrasound (POCUS), have also demonstrated promising test characteristics in diagnosing SBO. A potential new workflow for assessing patients with suspected SBO may be to use POCUS for diagnostic imaging with clinical variables to determine the need for urgent surgery. The main limitation of our study is that it is not clear if all surgeries within our 24-hour cohort were urgent or emergent. Furthermore, classification or prospective studies are needed to determine CT’s role in determining operative intervention. Such studies may help elucidate a new workflow leading to lower health care costs and less radiation for this patient population.”
Clinical Features vs CT Findings to Estimate Need for Surgery in Small Bowel Obstruction
Sara Schulwolf et al.
JAMA Network Open. 2023;6(11):e2341376. doi:10.1001/jamanetworkopen.2023.41376 - Of 4478 cases of confirmed SBO, surgical management was required within 24 hours of presentation in 463 cases (10.3%), 48 hours of presentation in 575 cases (12.8%), and at any time during the patient’s index hospital admission in 962 cases (21.5%). A model combining 22 clinical features alone achieved the same performance (area under the receiver operating characteristic curve [AUROC]) in estimating the need for surgical SBO management as a model combining the same clinical features with 16 CT findings (Table) within 24 hours (AUROC [SD], 0.79 [0.01]; 95%CI, 0.77-0.82 vs AUROC [SD], 0.78 [0.01]; 95%CI, 0.76-0.81; P = .72) (Figure, A) and 48 hours (AUROC [SD], 0.77 [0.01]; 95%CI, 0.75-0.80 vs AUROC [SD], 0.77 [0.01]; 95%CI, 0.75-0.80; P = .82) (Figure, B) of presentation. Clinical features alone vs clinical features with CT findings were more accurate inestimating the need for surgery at all times (AUROC [SD], 0.75 [0.01]; 95%CI, 0.73-0.78 vs AUROC SD], 0.54 [0.02]; 95%CI, 0.51-0.57; P < .001).
Clinical Features vs CT Findings to Estimate Need for Surgery in Small Bowel Obstruction
Sara Schulwolf et al.
JAMA Network Open. 2023;6(11):e2341376. doi:10.1001/jamanetworkopen.2023.41376
- Purpose: The aim of the study was to develop a prediction model for closed-loop small bowel obstruction integrating computed tomography (CT) and clinical findings.
Conclusions: A random forest model found clinical factors including prior surgery, age, lactate, and imaging factors including whirl sign, fecalization, and U/C-shaped bowel configuration are helpful in improving the prediction of CLSBO. Individual CT findings in CLSBO had either high sensitivity or specificity, suggesting that accurate diagnosis requires systematic assessment of all CT signs.
Machine Learning Based Prediction Model for Closed-Loop Small Bowel Obstruction Using Computed Tomography and Clinical Findings
Goyal, Riya et al
J Comput Assist Tomography: 3/4 2022 - Volume 46 - Issue 2 - p 169-174 - Results: Surgery confirmed CLSBO in 185 of 223 patients with clinically suspected CLSBO. Age greater than 52 years showed 2.82 (95% confidence interval = 1.13–4.77) times higher risk for CLSBO (P = 0.021). Sensitivity/specificity of CT findings included proximal dilatation (97/5%), distal collapse (96/2%), mesenteric edema (94/5%), pneumatosis (1/100%), free air (1/98%), and portal venous gas (0/100%). The random forest model combining imaging/clinical findings yielded an area under receiver operating curve of 0.73 (95% confidence interval = 0.58–0.94), sensitivity of 0.72 (0.55–0.85), specificity of 0.8 (0.28–0.99), and accuracy of 0.73 (0.57–0.85). Prior surgery, age, lactate, whirl sign, U/C-shaped bowel configuration, and fecalization were the most important variables in predicting CLSBO.
Machine Learning Based Prediction Model for Closed-Loop Small Bowel Obstruction Using Computed Tomography and Clinical Findings
Goyal, Riya et al
J Comput Assist Tomography: 3/4 2022 - Volume 46 - Issue 2 - p 169-174 - “CT imaging provides the ability to prognosticate the need for eventual surgical intervention throughout hospitalization, which can reduce mortality, morbidity and length of hospitalization. There are several specific imaging findings including mesenteric edema and unenhancement of the bowel wall which are predictive of a need for urgent surgical exploration. Oral contrast administration is not needed in patients with suspected high-grade obstruction, however, water-soluble oral contrast can predict the need for surgery in patients with suspected low-grade/partial SBO who were initially treated non-operatively.”
Computed Tomography in Emergency Diagnosis and Management Considerations of Small Bowel Obstruction for Surgical vs. Non-surgical Approach
Saeed Taghavifar et al.
Current Medical Imaging, 2022, 18, 275-284 - “About 90% of SBO cases are secondary to hernias, neoplasms and adhesions. Among these causes, adhesions represents 55-75% of cases, while the remaining portion of patients are due to tumors and hernias.”
Computed Tomography in Emergency Diagnosis and Management Considerations of Small Bowel Obstruction for Surgical vs. Non-surgical Approach
Saeed Taghavifar et al.
Current Medical Imaging, 2022, 18, 275-284 - “Gastrointestinal spread from MM is relatively common, with the SB representing the most common site of involvement. However, SB involvement is still vastly underappreciated clinically, with studies reporting the presence of lesions in 43.5–60% of cases postmortem, but only 1.5–4.4% antemortem. SB melanoma metastases are frequently multiple, due to haematogenous dissemination, and preferentially affect the terminal ileum and jejunum. As in our reported cases, SB metastases are more common with cutaneous as opposed to non-cutaneous melanomas. Primary mucosal melanomas arising in the SB are rare, remaining a controversial diagnosis as the possibility of a MM from an unidentified or regressed primary cutaneous melanoma should always be considered.”
The forgotten appearance of metastatic melanoma in the small bowel
Eva Mendes Serrao et al.
Cancer Imaging (2022) 22:27
- “The extrinsic causes of SBO consist of blockage or compression from the outside of the bowel with subsequent intestinal strangling and strangulation.The typical mechanism which causes this type of blockage usually refers to adhesional bands, adhesions and perivisceritis. The adhesions are mainly formed afterabdominal surgical interventions (80%), but also congenitalor inflammatory bands (such as peritoneal carcinomatosis,appendicitis or diverticulitis) (10%) and idiopathic bands (10%) exist. The adhesion is represented bya fibrous tissue band which joins surfaces or organs within the peritoneal cavity which are originally well distinct. Such adhesions represent the consequence of a pathological healing response after a surgical peritoneal violation as opposed to a natural repair.”
Small bowel obstruction and intestinal ischemia: emphasizing the role of MDCT in the management decision process
Mariano Scaglione et al.
Abdominal Radiology (2022) 47:1541–1555 - Small Bowel Obstruction: Causes
- Extrinsic
--- Adhesions
--- Hernias (internal and external)
--- Endometriosis
--- Neoplasms (extraintestinal)
- Intrinsic
--- Inflammatory/infectious diseases
--- Neoplasms of the small bowel (primary
and secondary)
--- Vascular causes (mesenteric ischemia)
--- Intramural hematoma
--- Radiation enteritis
--- Intussusception
- Intraluminal
--- Gallstone ileus
--- Bezoars
--- Foreign bodies - "The most important criterion consists of dilatation of small bowel loops with thickened/packed valvulae conniventes and air–fluid stasis. The second major criterion for SBO diagnosis is the transition point identification. The “transition point” corresponds to the passage from dilated to decompressed distal small bowel loops and identifies the place where the obstructing process is located. However, the transition point identification is not always easy, and the reported accuracy of detection may vary significantly, ranging from 63 to 93%, depending essentially on the degree of bowel dilatation from one side and the adjacent collapsed loops on the other.”
Small bowel obstruction and intestinal ischemia: emphasizing the role of MDCT in the management decision process
Mariano Scaglione et al.
Abdominal Radiology (2022) 47:1541–1555 - "In high grade or in chronic obstructions, endoluminal stasis and gascreate an appearance rather similar to feces in colon, the“small-bowel feces” sign. The prevalence of this sign ranges from 6 to 37%. This feature is usually evident just proximal to the transition point and can help localize it. However, it has shown a poor correlation in patients requiring a surgical approach for SBO.”
Small bowel obstruction and intestinal ischemia: emphasizing the role of MDCT in the management decision process
Mariano Scaglione et al.
Abdominal Radiology (2022) 47:1541–1555 - "This kind of SBO occurs when two adjacent sites of obstruction are present, separating the obstructed loop from the remainder segments of the gastrointestinal system which remains of normal caliber. The obstructed loop continues to produce fluid, thus becoming progressively dilated. This determines compression of supporting mesentery and increases venous return with subsequent ischemia. For this reason, it is considered a surgical emergency. Once this process is well established and peristalsis continues around a narrow point, the closed loop may twist along itsmajor axis and a “volvulus”, that is a bowel torsion on the own axis, may occur.”
Small bowel obstruction and intestinal ischemia: emphasizing the role of MDCT in the management decision process
Mariano Scaglione et al.
Abdominal Radiology (2022) 47:1541–1555 - “The most common cause of closed loop to search for is a single adhesive band, and the incidence is high particularly in patients after Roux-en-Y gastric bypass or simply after previous laparotomies for any other reason. Other causes include internal hernias, congenital or iatrogenic defects in the mesentery or omentum that may lead to catch a part of the bowel causing a closed-loop obstruction. The classic appearance of a closed-loop obstruction isthe “C”- or “U”-shaped configuration with the mesenteric vessels converging toward the site of obstruction. This appearance also named “spoke-wheel sign” is related to bowel ischemia in up to 46% of patients.The supporting vessels radially convergeon a single central point.”
Small bowel obstruction and intestinal ischemia: emphasizing the role of MDCT in the management decision process
Mariano Scaglione et al.
Abdominal Radiology (2022) 47:1541–1555 - Small Bowel Obstruction: CT Findings
- Reduced bowel wall enhancement
- Spontaneous hyperattenuation of the bowel wall.
- Presence of “target sign”
- Increase of thickness of the bowel wall. - • Reduced bowel wall enhancement. It is the most common sign of bowel ischemia and its specificity ranges from 94 and 100% . This sign is seen by comparing the attenuation values within the wall of an obstructed bowel loop with the attenuation of bowel loops away from the site of obstruction. Even if this is the most specific sign, it can be a transient feature and can thus be unremarkable during an intermediate phase, while the angiogram may demonstrate a very high bowel wall enhancement in a later phase.
• Spontaneous hyperattenuation of the bowel wall. It is far more common in strangulated SBO than in conditions of transmural necrosis or non-occlusive mesenteric ischemia. In fact, the main cause of wall hyperattenuation is mesenteric venous occlusion which determines submucosal or transmural hemorrhage
Small bowel obstruction and intestinal ischemia: emphasizing the role of MDCT in the management decision process
Mariano Scaglione et al.
Abdominal Radiology (2022) 47:1541–1555 - Presence of “target sign”. This sign refers to a circumferential low-attenuation halo in a thickened bowel wall related to a submucosal bowel wall edema. The three layer wall attenuations are better identified in the late arterial and early portal venous phase after intravenous contrast material administration. Sometimes, the target sign can be also appreciated at non-enhanced CT scans. Although it is present in 47% of patients with intestinal ischemia, this is a relatively nonspecific sign which can be referred other possible etiologies such as idiopathic inflammatory bowel diseases, vascular disorders, infectious colitis and pseudomembranous colitis where other methodologies, such as MRI, can help for differential diagnosis.
Small bowel obstruction and intestinal ischemia: emphasizing the role of MDCT in the management decision process
Mariano Scaglione et al.
Abdominal Radiology (2022) 47:1541–1555 - “The whirl sign was described for the first time by Fisher at CT in a patient with a volvulus, with the whirled appearance related to a circling loops of bowel around the superior mesenteric artery. Congenital or acquired abnormalities in peritoneal attachment, such as iatrogenic adhesions after surgical procedures, predispose development of volvulus. Although it is considered non-specific, the whirl sign is highly suggestive for complicated closed bowel obstruction. According to Thompson et al, the whirl sign has a sensitivity of 60% and a positive predictive value of 80% in patients who need a laparotomy for SBO. Therefore, searching for and recognizing the whirl sign is of extreme importance for the related high risk of ischemia patients and subsequent urgent surgical assessment and repair.”
Small bowel obstruction and intestinal ischemia: emphasizing the role of MDCT in the management decision process
Mariano Scaglione et al.
Abdominal Radiology (2022) 47:1541–1555 - "SBO is a complex clinical condition that may be caused by different entities. In patients with suspected SBO, recognizing the type, site, cause and presence of complication is crucial not only for diagnosis but to assign a correct and timely management approach. Contrast-enhanced MDCT is the most efficient technique we have to assess the presence of SBO and to rule out life-threatening complications including strangulated bowel loops, volvulus or closedloop obstruction. These signs have strong implications for determining the prognosis and surgical strategy. If early surgery of a strangulated bowel obstruction is not carried out, bowel gangrene, infarction and surgical bowel resection are unavoidable consequences. The radiologists in the emergency setting must become familiar with these features and interact with the surgeons, thus becoming a crucial member of the Emergency Team.”
Small bowel obstruction and intestinal ischemia: emphasizing the role of MDCT in the management decision process
Mariano Scaglione et al.
Abdominal Radiology (2022) 47:1541–1555 - “Luminal dilatation is a non-specific finding in acute mesenteric ischemia and can be seen in bowel obstruction and paralytic ileus. Bowel wall thickening with target appearanceis also seen in acute stage of Crohn’s disease, infectious enteritis, acute radiation enteritis, shock bowel mimicking veno-occlusive disease. The pattern of bowel involvement (segmental with skip areas in Crohn’s disease), normal portomesentericvenous contrast opacification with specific clinical or prior treatment history may help in differentiating these entities from veno-occlusive mesenteric ischemia. Pneumatosis intestinalis, although considered a sign of acute ischemic damage to bowel mucosa, it may be associated with several benign conditions like connective tissue disease, emphysema, asthma, and intra-abdominal procedures.”
Mesenteric ischemia: a radiologic perspective
Dimpi Sinha et al.
Abdominal Radiology (2022) 47:1514–1528
- “Time to surgery” is the most important prognostic factor as mortality significantly increases with the duration of symptoms. Ritz et al. determined that the survival rate in the first 12 h was 84.3%, compared with only 11.6% after 24 h and 2% after 48 h [4]. In response to this serious emergency condition, all patients with a high index of clinical suspicion of ASBI should be assessed via contrast-enhanced CT.”
Comprehensive review of acute small bowel ischemia: CT imaging findings, pearls, and pitfalls
Sitthipong Srisajjakul · Patcharin Prapaisilp · Sirikan Bangchokdee
Emergency Radiology (2022) 29:531–544 - "Bowel wall thickening is the commonest finding of small bowel ischemia. It is more common in venous ischemia than arterial ischemia due to venous stasis resultingin edema and hemorrhage. The thickening is typically circumferential, homogeneous, and uniform, and itis depicted as a halo or target sign (increased enhancement of the mucosa and serosa surrounding a submucosal, low attenuating,edematous layer).”
Comprehensive review of acute small bowel ischemia: CT imaging findings, pearls, and pitfalls
Sitthipong Srisajjakul · Patcharin Prapaisilp · Sirikan Bangchokdee
Emergency Radiology (2022) 29:531–544 - "Bowel wall thinning is a common feature of small bowel arterial ischemia. The bowel wall can become markedly thin or severely thin (a paper-thin appearance or a vanishing bowel wall). This finding results from a loss of arterial blood flow to the bowel wall mucosa, which can progress to transmural infarction.”
Comprehensive review of acute small bowel ischemia: CT imaging findings, pearls, and pitfalls
Sitthipong Srisajjakul · Patcharin Prapaisilp · Sirikan Bangchokdee
Emergency Radiology (2022) 29:531–544 - "Mesenteric arterial emboli usually originate in the heart or aorta and then float before lodging to form an arterial occlusion. The SMA is the most affected artery because of its more vulnerable takeoff angle from the aorta, compared with the celiac and inferior mesenteric arteries . The two vascular signs depend on the extent of the occlusion. The cut-off sign refers to the abrupt termination of contrast in the vessel due to acute occlusive emboli in the distal branch, while the ring sign refers toan eccentric filling defect in the vascular lumen due to nonocclusive emboli.”
Comprehensive review of acute small bowel ischemia: CT imaging findings, pearls, and pitfalls
Sitthipong Srisajjakul · Patcharin Prapaisilp · Sirikan Bangchokdee
Emergency Radiology (2022) 29:531–544
- Spigelian Hernia: Facts
- A Spigelian Hernia is a rare ventral hernia which is defined as herniation of abdominal contents or peritoneum through a defect, namely the Spigelian fascia which is comprised of the transversus abdominis and the internal oblique aponeuroses.
- Patients may describe a painful or painless “bulge” in their abdominal wall, particularly when standing, that may acute or chronic onset. Depending on the contents contained within the hernia, pain may vary greatly in terms of severity, character, or location. Commonly, patients will present in the urgent setting secondary to complications associated related to a hernia. - Spigelian Hernia: Facts
- Unlike other ventral hernias, Spigelian hernias are not amenable to conservative treatment including watchful waiting. Due to the high rate of incarceration and subsequent strangulation, operative repair is recommended and has become the mainstay of treatment. There are several options in regard to surgical management of Spigelian hernias. Repair of Spigelian hernias may be done in an open, laparoscopic, or even robotic approach.
- OBJECTIVE. The objective of our study was to evaluate if the feces sign can be used to predict successful nonoperative treatment or progression to ischemia in patients with small- bowel obstruction (SBO) due to adhesions.
CONCLUSION. The feces sign is common and helps to identify the TZ. Among the CT signs of SBO, the feces sign does not independently help to predict successful nonoperative treatment or progression to ischemia.
Clinical Relevance of the Feces Sign in Small-Bowel Obstruction Due to Adhesions Depends on Its Location Wassef Khaled et al. AJR 2018; 210:78–84 - “Mechanical small-bowel obstruction (SBO) is a common cause of abdominal pain that accounts for 10–20% of emergency department visits and 20–25% of surgical admissions. Treatment of SBO has shifted toward a more conservative management when there are not any clinicobiologic or imaging findings suggestive of progression to ischemia. Consensus now exists in favor of recommending the use of MDCT in the evaluation of patients with SBO. The main challenges for the radiologist are, first, to rule out an ischemic complication and, second, to look for CT signs predictive of the effectiveness of medical treatment that would enable the surgeon to
confidently select this management strategy.”
Clinical Relevance of the Feces Sign in Small-Bowel Obstruction Due to Adhesions Depends on Its Location Wassef Khaled et al. AJR 2018; 210:78–84 - “In conclusion, in a large population of patients with SBO due to adhesions, we found the existence of several feces sign variants, which have different clinical meanings. However, none of these variants independently improved the prediction of successful nonoperative treatment or ischemia compared with previously validated CT signs.”
Clinical Relevance of the Feces Sign in Small-Bowel Obstruction Due to Adhesions Depends on Its Location Wassef Khaled et al. AJR 2018; 210:78–84 - “Sprue-like enteropathy associated with the angiotensin II receptor blocker (ARB) olmesartan was first described in 2012, and a number of cases have since been reported. This syndrome is characterized by severe diarrhea and sprue-like histopathologic findings in the intestine, often with increased subepithelial collagen. The incidence of this adverse drug reaction is not entirely clear, although it is thought to be rare. It is also not well established if other ARBs cause such a syndrome, although case reports suggest they can. The histopathologic features of olmesartan-related injury have only been described in a limited number of cases, and there are no guidelines regarding the histopathologic distinction of olmesartan-associated enteropathy from other causes of sprue (eg, celiac disease, tropical sprue).”
Olmesartan-associated sprue-like enteropathy: a systematic review with emphasis on histopathology. Burbure N et al. Hum Pathol. 2016 Apr;50:127-34
- “The CT findings of a closed-loop ob- struction depend in part on the orientation of the loop relative to the plane of imaging. If the loop is within the plane of imaging, the lesions often appear as a “U,” “C,” or “coffee bean” configuration pointing to the site of twist.” Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology 2015; 275:332–342
- CT Findings of Bowel Ischemia
• Bowel wall thickening > 3cm
• Mesenteric edema
• Fluid in mesentery and/or peritoneal cavity
• Abnormal bowel wall enhancement (increased or decreased)
• Occlusion of mesenteric vessels
• Engorged mesenteric veins
• Whirl sign
• Closed loop obstruction or volvulus
• Pneumatosis
• Mesenteric venous gas
• Portal venous gas - Closed loop obstruction: Definition
Closed loop obstruction is a specific type of obstruction in which two points along the course of a bowel are obstructed at a single location thus forming a closed loop. Usually this is due to adhesions, a twist of the mesentery or internal herniation. - OBJECTIVE: Small bowel gastrointestinal stromal tumors (SB-GISTs) are rare lesions with a variable appearance on computed tomography (CT). This case series analyzes the CT enhancement pattern with the histologic risk assessment of tumor progression.
CONCLUSIONS: This case series reveals an important significant association between heterogeneous enhancement and non-low risk (ie, moderate/high) SB-GISTs. Beyond just describing the tumor, using enhancing pattern, the interpreting radiologist can preoperatively suggest additional prognostic information, potentially helpful for surgical planning.
Small Bowel Gastrointestinal Stromal Tumors: Multidetector Computed Tomography Enhancement Pattern and Risk of Progression. Verde F1, Hruban RH, Fishman EK. J Comput Assist Tomogr. 2017 May/Jun;41(3):407-411.
- “SBO is frequently encountered in clinical practice, accounting for an estimated 300,000–350,000 hospital admissions yearly in the United States, and approximately 15% of all surgical admissions.”
MDCT findings in small bowel obstruction: implications of the cause and presence of complications on treatment decisions O’Malley RG et al. Abdom Imaging (2015) 40:2248–2262 - “In patients presenting acutely with high clinical suspicion of SBO and/or suggestive findings on initial screening abdominal radiographs, multi-detector computed tomography (MDCT) evaluation is the most commonly utilized imaging test for establishing the diagnosis of SBO with reported sensitivity of 90–96%, specificity of 96%, and accuracy of 95%.”
MDCT findings in small bowel obstruction: implications of the cause and presence of complications on treatment decisions O’Malley RG et al. Abdom Imaging (2015) 40:2248–2262 - Small Bowel Obstruction: Analysis of the Scan
• Is the bowel dilated?
• If the bowel is dilated can you define a transition point between dilated small bowel and normal caliber small bowel
• What is the cause of the transition?
• What other findings are present in the mesentery and vascular tree - “Once SBO has been diagnosed by identifying asymmetrically dilated proximal small bowel loops leading to an abrupt transition zone, the radiologist next must try to identify certain findings that suggest the cause of the obstruction (e.g., adhesions, closed loop obstruction, volvulus, internal hernia, or intraluminal impaction) and assess for signs of bowel wall vascular compromise (e.g., bowel wall edema, inter-loop fluid, altered bowel wall enhancement, pneumatosis, portomesenteric gas).”
MDCT findings in small bowel obstruction: implications of the cause and presence of complications on treatment decisions O’Malley RG et al. Abdom Imaging (2015) 40:2248–2262 - Small Bowel Feces Sign
In some patients with SBO, particularly those with long- standing or subacute obstruction, the ‘‘small bowel feces sign’’ can be seen. This sign refers to the presence of mottled fecal-like material in the dilated small bowel immediately proximal to the transition zone, resembling colonic contents. Without bowel dilatation, the presence of fecal-like material in the small bowel is an incidental finding, which can be seen in asymptomatic patients or may indicate stasis with increased water resorption or bacterial overgrowth. In fact, a series by Jacobs et al. identified the small bowel feces sign more commonly in patients without SBO (68%).
MDCT findings in small bowel obstruction: implications of the cause and presence of complications on treatment decisions O’Malley RG et al. Abdom Imaging (2015) 40:2248–2262 - Small Bowel Feces Sign
“However, when associated with small bowel dilation, the small bowel feces sign may help identify the location of the transition zone. In the same study, Jacobs et al. found that all patients with small bowel feces sign and a dilated segment of small bowel >3 cm had SBO and, of those, the small bowel feces sign was just proximal to the transition zone in 75% of the cases.”
MDCT findings in small bowel obstruction: implications of the cause and presence of complications on treatment decisions O’Malley RG et al. Abdom Imaging (2015) 40:2248–2262 - SBO and Transition Zones
• Extrinsic bowel wall
• Intrinsic bowel wall
• Intraluminal pathologies - SBO and Transition Zones
• Extrinsic bowel wall (adhesive bands, external hernias (e.g., inguinal, femoral, Spigelian, umbilical, obturator, or incisional), extension of extra- enteric disease process from the mesentery to the bowel serosal surface (e.g., sclerosing mesenteritis, peritoneal carcinomatosis, endometriosis), and any inflammatory or infectious process adjacent to the small bowel that leads to reactive bowel wall edema)
• Intrinsic bowel wall
• Intraluminal pathologies - SBO and Transition Zones
• Extrinsic bowel wall
• Intrinsic bowel wall (causes include bowel wall inflammation or fibrosis (such as from ischemia, hematoma, infectious enteritides, Crohn’s disease, anastomotic stricture, or radiation enteropathy), intussusception, primary bowel neoplasms (e.g., adenocarcinoma, carcinoid, GIST, lymphoma), or metastatic lesions (e.g., melanoma, breast, distant primary GI tumors, etc.)
• Intraluminal pathologies - SBO and Transition Zones
• Extrinsic bowel wall
• Intrinsic bowel wall
• Intraluminal pathologies include gallstones (i.e., gallstone ileus), bezoars, thick intestinal secretions (e.g., cystic fibrosis) or ingested foreign body, which are usually visualized at the transition zone and identified by differential attenuation rela- tive to the intraluminal fluid - “Adhesions are exceedingly common, reportedly developing in up to 93% of patients who have undergone prior laparotomy and accounting for up to 85% of cases of SBO. However, it is also important to note that 10–15% of adhesions develop in patients without prior surgery, usually from prior episodes of inflammation or infection, and should be still considered as the cause of obstruction in this setting.”
Multidetector row computed tomography of small bowel obstruction. Desser TS, Gross M Semin Ultrasound CT MRI 29(5):308–321 - “The configuration of the obstructed bowel loops can be a clue to the diagnosis and site of the obstruction, often demonstrating a radial arrangement with a U- or C-shaped configuration, converging at the site of obstruction. If the closed loop rotates around its mesenteric axis and a volvulus develops, swirling of mesenteric vessels may also be identified.”
MDCT findings in small bowel obstruction: implications of the cause and presence of complications on treatment decisions O’Malley RG et al. Abdom Imaging (2015) 40:2248–2262 - “Although most cases of SBO resolve with conservative management, it is important to appreciate the difficulty when managing SBO, and specifically that the classic clinical signs of vascular compromise are often unreliable in predicting the need for operative intervention. As such, it is crucial to iden- tify the subset of patients with imaging findings suggesting bowel vascular compromise or those with causes or types of obstruction unlikely to resolve spontaneously in order to avoid life-threatening complications. The cause and type of obstruction, in addition to the presence or absence of findings suggesting ischemia, can improve confidence and help guide clinical decision-making of either conservative management or urgent surgical intervention.”
MDCT findings in small bowel obstruction: implications of the cause and presence of complications on treatment decisions O’Malley RG et al. Abdom Imaging (2015) 40:2248–2262
- “Small-bowel obstruction (SBO) continues to be a substantial cause of morbidity and mortality, accounting for 12%–16% of hospital admissions for the evaluation of acute abdominal pain in the United States. Most patients with SBO are treated successfully with nasogastric tube decompression. However, the mortality of SBO ranges from 2% to 8% and may increase to as high as 25% if bowel ischemia is present and there is a delay in surgical management.”
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - “Small-bowel obstruction (SBO) is a substantial cause of morbidity and mortality, accounting for up to 16% of hospital admissions for acute abdominal pain in the United States.” Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42.
- “Multidetector CT has been proven to be the single best imaging tool for evaluating patients suspected of having SBO, with sensitivity and specificity of 95%; it is also highly accurate in detecting the complications of SBO.”
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - “Closed-loop obstruction occurs when a segment of bowel is obstructed at two points along its course, resulting in progressive accumulation of fluid in gas within the isolated loop, placing it at risk for volvulus and subsequent ischemia.”
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - “In conclusion, when evaluating patients suspected of having SBO, address the issues that are relevant to surgical management including the presence of SBO, site, cause, and presence of complications. It is critical to search care- fully for evidence of volvulus and closed- loop obstruction as these conditions are associated with strangulation and place patients at risk for ischemia.”
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - Five Questions to Address in Suspected SBO
1. is there SBO?
2. where is the location of the obstruction?
3. what is the cause of the obstruction?
4. are there any complications such as ischemia, volvulus or internal hernia?
5. how should the patient be treated?
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - Why do we use CT for evaluation of suspected SBO?
Abdominal radiography is usually the initial imaging modality in patients suspected of having SBO because it is widely available, is inexpensive, and has an accuracy of 50–86%.
Multidetector CT has been proven to be the single best imaging tool for evaluating patients suspected of having SBO, with sensitivity and specificity of 95%; it is also highly accurate in detecting the complications of SBO. - “In the Western world, the major cause of SBO is adhesions. The next two most frequent causes are hernias and malignancies. These three etiologies account for more than 80% of all causes of SBO. Other etiologies include Crohn disease, intussusception, volvulus, gallstones, foreign bodies, bezoars, trauma, and iatrogenic problems.”
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - External hernias are the second most frequent cause of SBO. They can occur throughout the abdomen and pelvis, but most frequently involve the inguinal canal or anterior abdominal wall. The hallmark of SBO due to her- nia is the presence of dilated bowel up to the hernia sac followed by decompressed bowel exiting from the sac.
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - Sixty to 70% of SBOs are caused by adhesions (3,4,56), which are usually the result of prior abdominal surgery, whether open or laparoscopic. Adhesions repre- sent bands of fibrous tissue that obstruct the lumen and are a consequence of the postoperative inflammatory process. They may lead to bowel obstruction in the early postoperative period or may obstruct years later. On CT scans, the adhesion itself is generally not identified. Rather, its presence is inferred when there is an abrupt transition from dilated to collapsed bowel without an identifi- able cause at the transition zone. As adhesions compress the bowel extrinsi- cally, they often cause an abrupt taper- ing or “beak” at the site of obstruction.
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - Definitions of SBO
1. Complete or high-grade obstruction indicates no fluid or gas passes beyond the site of obstruction.
2. Incomplete or partial obstruction indicates that some fluid or gas pass beyond the obstruction .
3. Strangulated obstruction indicates that blood flow is compromised, which may lead to intestinal ischemia, necrosis, and perforation.
4. Closed-loop obstruction occurs when a segment of bowel is obstructed at two points along its course, resulting in progressive accumulation of fluid in gas within the isolated loop, placing it at risk for volvulus and subsequent ischemia. - “In the Western world, the major cause of SBO is adhesions. The next two most frequent causes are hernias and malignancies . These three etiologies account for more than 80% of all causes of SBO. Other etiologies include Crohn disease, intussusception, volvulus, gallstones, foreign bodies, bezoars, trauma, and iatrogenic problems.”
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - “Sixty to 70% of SBOs are caused by adhesions, which are usually the result of prior abdominal surgery, whether open or laparoscopic. Adhesions represent bands of fibrous tissue that obstruct the lumen and are a consequence of the postoperative inflammatory process. They may lead to bowel obstruction in the early postoperative period or may obstruct years later.”
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - “On CT scans, the adhesion itself is generally not identified. Rather, its presence is inferred when there is an abrupt transition from dilated to collapsed bowel without an identifiable cause at the transition zone. As adhesions compress the bowel extrinsically, they often cause an abrupt tapering or “beak” at the site of obstruction.”
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - “External hernias are the second most frequent cause of SBO. They can occur throughout the abdomen and pelvis, but most frequently involve the inguinal canal or anterior abdominal wall. The hallmark of SBO due to her- nia is the presence of dilated bowel up to the hernia sac followed by decompressed bowel exiting from the sac.”
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42. - “The CT findings of a closed-loop obstruction depend in part on the orientation of the loop relative to the plane of imaging. If the loop is within the plane of imaging, the lesions often appear as a “U,” “C,” or “coffee bean” configuration pointing to the site of twist. If orthogonal to the plane of imaging, dilated bowel in a radial configuration may be encountered.”
Review of Small-Bowel Obstruction: The Diagnosis and When to Worry Paulson EK, Thompson WM Radiology. 2015 May;275(2):332-42.
- “ Three CT features were frequently associated with operative management and had good concordance between radiologists: complete bowel obstruction, small bowel dilation greater than 4 cm and transition point. Transition point was the only significant factor predictive of operative management for SBO on multivariable logistic regression analysis (OR 19, 95% confidence interval 1.8-201, p = 0.014).”
Computed tomography features associated with operative management for nonstrangulating small bowel obstruction
Suri RR et al.
Can J Surg. 2014 Aug;57(4):254-9. - “In patients with nonstrangulating SBO, the presence of a transition point on CT scan should alert the surgeon to the increased likelihood that operative management may be required.”
Computed tomography features associated with operative management for nonstrangulating small bowel obstruction
Suri RR et al.
Can J Surg. 2014 Aug;57(4):254-9. - “To evaluate performance of increased bowel-wall attenuation on unenhanced 64-section multidetector computed tomographic (CT) images for diagnosing bowel-wall ischemia in patients with mechanical small-bowel obstruction (SBO) and to evaluate the diagnostic accuracy of multidetector CT in detecting small-bowel ischemia complicating SBO, with surgical and histopathologic findings as reference standard.”
Increased unenhanced bowel-wall attenuation at multidetector CT is highly specific of ischemia complicating small-bowel obstruction.
Geffroy Y et al.
Radiology. 2014 Jan;270(1):159-67 - “In 19 of 45 (42%) multidetector CT scans, ischemia was confirmed at surgery and/or histopathologic examination. Increased bowel-wall attenuation on unenhanced images was significantly associated with ischemia (P < .0001); in this highly selected population, this sign had a 100% (24 of 24) specificity and a 56% (10 of 18) sensitivity. Sensitivity and specificity of multidetector CT for ischemia were 63% (12 of 19) and 92% (24 of 26), respectively, for the prospective reports and 84% (16 of 19) and 96% (25 of 26), respectively, for the consensus review.”
Increased unenhanced bowel-wall attenuation at multidetector CT is highly specific of ischemia complicating small-bowel obstruction.
Geffroy Y et al.
Radiology. 2014 Jan;270(1):159-67 - “Controversy remains as to which patients with small bowel obstruction (SBO) need immediate surgery and which may be managed conservatively. This study evaluated the ability of clinical risk factors to predict the failure of nonoperative management of SBO.”
Letting the sun set on small bowel obstruction: can a simple risk score tell us when nonoperative care is inappropriate?
O'Leary EA et al.
Am Surg. 2014 Jun;80(6):572-9. - “ Eighty-five per cent of patients with none of these four significant risk factors were successfully managed nonoperatively. Conversely, 92 per cent of patients with three or more risk factors required laparotomy.”
Letting the sun set on small bowel obstruction: can a simple risk score tell us when nonoperative care is inappropriate?
O'Leary EA et al.
Am Surg. 2014 Jun;80(6):572-9. - “Univariate analysis showed that persistent abdominal pain, abdominal distention, nausea and vomiting, guarding, obstipation, elevated white blood cell count, fever present 48 hours after hospitalization, and high-grade obstruction on computed tomography (CT) scan were significant predictors of the need for surgery. Multivariable analysis revealed that persistent abdominal pain or distention (hazard ratio [HR], 3.04; P = 0.013), both persistent abdominal pain and distention (HR, 4.96; P < 0.001), fever at 48 hours (HR, 3.66; P = 0.038), and CT-determined high-grade obstruction (HR, 3.45; P = 0.017) independently predicted the need for surgery.”
Letting the sun set on small bowel obstruction: can a simple risk score tell us when nonoperative care is inappropriate?
O'Leary EA et al.
Am Surg. 2014 Jun;80(6):572-9. - “Univariate analysis showed that persistent abdominal pain, abdominal distention, nausea and vomiting, guarding, obstipation, elevated white blood cell count, fever present 48 hours after hospitalization, and high-grade obstruction on computed tomography (CT) scan were significant predictors of the need for surgery.”
Letting the sun set on small bowel obstruction: can a simple risk score tell us when nonoperative care is inappropriate?
O'Leary EA et al.
Am Surg. 2014 Jun;80(6):572-9.
- Closed Loop Obstruction: CT Findings
- C or U shaped distended loops with the mesenteric vessels converging toward the site of obstruction
- Site of obstruction usually clear or CT especially with MPR views - CT Evaluation of Small Bowel Obstruction: Questions
- Is obstruction present?
- What is the severity of obstruction?
- Where is the transition zone?
- What is the cause of obstruction? - "MDCT can be am alternative to barium studies of the small bowel for evaluation of the small bowel in patients with inflammatory bowel disease. MDCT also offers additional, clinically relevant information not obtained by small bowel barium series."
Comparison of Multidetector CT and Barium Studies of the Small Bowel: Inflammatory Bowel Disease in Children Jamieson DH et al. AJR 2003; 180:1211-1216