Omental infarction and its mimics: imaging features of acute abdominal conditions presenting with fat stranding greater than the degree of bowel wall thickening

Surgical Complication of Omental Infarction in Ulcerative Colitis Following Laparoscopic Colectomy

Omental infarction is a rare cause of acute abdomen, often mimicking more common abdominal emergencies such as appendicitis and cholecystitis, presenting significant diagnostic challenges. A 47-year-old male with a history of ulcerative colitis underwent laparoscopic total colectomy with end ileostomy. Postoperatively, he developed severe abdominal pain, chills, nausea, and increased abdominal distension. Despite having output from his ileostomy, his symptoms persisted. A CT scan revealed free intraperitoneal air and significant intra-abdominal fluid, indicating potential intra-abdominal injury. Diagnostic laparoscopy identified an infarcted omentum and 850 mL of hemoperitoneum. An omentectomy was performed, and the patient received supportive care postoperatively, leading to gradual improvement in symptoms and recovery. In this case, surgical intervention was required due to severe symptoms, diagnostic uncertainty, and associated hemoperitoneum. While conservative management has been described in stable cases, this approach was not appropriate for our patient. Advanced imaging techniques, particularly CT, remain crucial for identifying omental infarction, but clinical judgment and individual patient factors ultimately guide management decisions.

Are all primary omental infarcts truly idiopathic? Five case reports

BACKGROUND

Idiopathic omental infarction (IOI) is challenging to diagnose due to its low incidence and vague symptoms. Its differential diagnosis also poses difficulties because it can mimic many intra-abdominal organ pathologies. Although hypercoagulability and thrombosis are among the causes of omental infarction, venous thromboembolism scanning is rarely performed as an etiological investigation.

CASE SUMMARY

The medical records of the 5 cases, who had the diagnosis of IOI by computed tomography, were examined. The majority of the patients were male (n = 4, 80%) and the mean age was 31 years (range: 21-38). The patients had no previous abdominal surgery or a history of any chronic disease. The main complaint of all patients was persistent abdominal pain. Omental infarction was detected in all patients with contrast-enhanced computed tomography. Conservative treatment was initially preferred in all patients, but it failed in 1 patient (20%). After discharge, all patients were referred to the hematology department for thrombophilia screening. Only 1 patient applied for thrombophilia screening and was homozygous for methylenetetrahydrofolate reductase (A1298C mutation) and heterozygous for a factor V Leiden mutation.

CONCLUSION

IOI should be considered in the differential diagnosis in patients presenting with progressive and/or persistent right side abdominal pain. Investigating risk factors such as hypercoagulability in patients with IOI is also important in preventing future conditions related to venous thromboembolism.

Spontaneous omental infarction as a rare differential for right iliac fossa pain: A case report and review of the literature

Omental infarction is a rare cause of acute abdominal pain, often benign and self-limiting. The significance of infarction lies in the fact that it can mimic other abdominal pathologies including appendicitis, cholecystitis, pancreatitis, or reflux disease. Diagnostic laparoscopy provides the definitive diagnosis of omental infarction, but it is invasive and limited due to resources. Computed tomography of the abdomen and pelvis has been considered the gold standard to diagnosing omental infarction when a non-invasive diagnostic approach is required. Additionally, ultrasound can also be used alternatively for children. Currently, there is no consensus in the diagnosis and management of patients with imaging-proven omental infarction. Spontaneous infarcted omentum must be considered by surgeons and radiologists as a rare cause of acute abdominal pain as patients can experience good outcomes with either conservative or operative approach. However, conservative management must only be considered in stable patients where alternative pathology is unlikely.

Omental infarction diagnosed by computed tomography, missed with ultrasonography: A case report

BACKGROUND

Omental infarction (OI) is a surgical abdominal disease that is not common in adults and is very rare in children. Similar to various acute abdominal pain diseases including appendicitis, diagnosis was previously achieved by diagnostic laparotomy but more recently, ultrasonography or computed tomography (CT) examination has been used.

CASE SUMMARY

A 6-year-old healthy boy with no specific medical history visited the emergency room with right lower abdominal pain. He underwent abdominal ultrasonography by a radiologist to rule out acute appendicitis. He was discharged with no significant sonographic finding and symptom relief. However, the symptoms persisted for 2 more days and an outpatient visit was made. An outpatient abdominal CT was used to make a diagnosis of OI. After laparoscopic operation, his symptoms resolved.

CONCLUSION

In children’s acute abdominal pain, imaging studies should be performed for appendicitis and OI.

Imaging of Mischievous Intra-abdominal Fat Presenting with Abdominal Pain: A Pictorial Review

Aim

To briefly discuss the imaging features of different types of intra-abdominal fat necrosis.

Background

Trauma and ischemic insult may result in intra-abdominal fat necrosis. Fat necrosis may present with acute abdomen, clinically simulating with other etiologies, such as acute diverticulitis and acute appendicitis.

Main body

Imaging plays a crucial role in making the exact diagnosis and differentiating it from other pathologies that may require surgical intervention. Computed tomography (CT) is the most commonly used imaging modality. A small fat attenuation lesion with a hyperattenuating rim in contact with the ventral surface of the sigmoid colon indicates epiploic appendagitis while a larger fat-attenuation lesion on the right side of the abdomen in between the colon and anterior abdominal wall indicates omental infarction. Fat stranding at the root of the mesentery with fat ring sign represents inflammatory mesenteric panniculitis while retractile or sclerosing mesenteritis appears as a fibrotic spiculated mass with or without calcification, mimicking mesenteric carcinoid. In patients with acute pancreatitis, the amount of inflamed fat correlates with clinical severity and outcome.

Conclusions

Familiarity with the imaging features of different types of intraabdominal fat necrosis helps in establishing an accurate diagnosis, thus avoiding unnecessary intervention.

How to cite this article

Patel RK, Mittal S, Singh S. Imaging of Mischievous Intra-abdominal Fat Presenting with Abdominal Pain: A Pictorial Review. Euroasian J Hepato-Gastroenterol 2022;12(1):45–49.

Colonic involvement in acute mesenteric ischemia: prevalence, risk factors, and outcomes

OBJECTIVES

This study aimed to investigate the prevalence, risk factors, and outcomes of colonic involvement in patients with acute mesenteric ischemia (AMI).

METHODS

CT scans from a prospective cohort of 114 AMI patients treated in an intestinal stroke center between 2009 and 2018 were blindly reviewed by two radiologists. Colon involvement was defined on CT scan by the presence of at least one of the following CT colonic features: wall thickening, pneumatosis, decreased wall enhancement, dilatation, or perforation. In addition, the clinical, biological, and radiological characteristics of patients with and without colonic involvement were compared to identify risk factors for colonic involvement on CT and its impact on morbidity and mortality.

RESULTS

Colonic involvement was identified in 32/114 (28%) patients with AMI, the right colon being more frequently involved (n = 29/32, 91%). Wall thickening (n = 27/32) was the most common CT finding. Occlusion of the inferior mesenteric artery was the only statistically significant risk factor for colonic involvement (35% vs. 15%, p = 0.02). Patients with colonic involvement on CT vs. those without had more frequently transmural colonic necrosis (13% vs. 0%, p = 0.006), short bowel syndrome (16% vs. 4%, p = 0.04), need for long-term parenteral support (19% vs. 5%, p = 0.03), and death during follow-up (22% vs. 10%, p = 0.03).

DISCUSSION

In patients with AMI, colonic involvement is associated with increased morbidity and mortality and should be carefully searched for during initial CT scan assessment.

KEY POINTS

• In a prospective cohort of acute mesenteric ischemia patients from an intestinal stroke center, 28% had an associated colonic involvement on CT. • Colonic involvement on CT most commonly affected the right colon, and the occlusion of the inferior mesenteric artery was the only risk factor. • Colonic involvement on CT was associated with increased morbidity and mortality and should be carefully searched for during initial CT scan assessment.

Omental Infarction: An Underrecognized Cause of Right-Sided Acute Abdominal Pain in Children

OBJECTIVE

To evaluate the prevalence of omental infarction (OI) in children with suspected appendicitis, the role of ultrasonography (US) in its diagnosis and management and the efficacy of conservative management.

METHODS

Consecutive children with suspected acute appendicitis were prospectively enrolled. Ultrasonography was performed at baseline, during follow-up, before the discharge, and at 15-day intervals until US findings of OI disappeared. All children with a diagnosis of OI were treated conservatively.

RESULTS

One hundred ninety-nine children (91 male; age range, 3-15 years) were evaluated. Eighty-four patients had acute appendicitis. Omental infarctions were found in 14 children (8 male; mean age, 9.8 ± 2.6 years), with an incidence of 7%. Ultrasonography depicted an echogenic mass consistent with OI in all children. Ultrasonography detected in 8 patients a normal-looking appendix, whereas in other 6 patients, it identified neither appendix nor indirect signs of acute appendicitis. A normal appendix has been detected by US during follow-up in 2 of these 6 patients. During follow-up, US finding of OI disappeared in all cases and no signs of acute appendicitis or other disease occurred. All 14 OIs were treated conservatively, with no reported complications.

CONCLUSIONS

Omental infarction is an underestimated cause of abdominal pain in children accounting for 7% of patients with suspected appendicitis. Ultrasonography is a useful method for the diagnoses and to guide clinical management of OI. Conservative therapy is a safe option for the management of OI.

Pancreatic triglyceride lipase mediates lipotoxic systemic inflammation

Visceral adipose tissue plays a critical role in numerous diseases. Although imaging studies often show adipose involvement in abdominal diseases, their outcomes may vary from being a mild self-limited illness to one with systemic inflammation and organ failure. We therefore compared the pattern of visceral adipose injury during acute pancreatitis and acute diverticulitis to determine its role in organ failure. Acute pancreatitis-associated adipose tissue had ongoing lipolysis in the absence of adipocyte triglyceride lipase (ATGL). Pancreatic lipase injected into mouse visceral adipose tissue hydrolyzed adipose triglyceride and generated excess nonesterified fatty acids (NEFAs), which caused organ failure in the absence of acute pancreatitis. Pancreatic triglyceride lipase (PNLIP) increased in adipose tissue during pancreatitis and entered adipocytes by multiple mechanisms, hydrolyzing adipose triglyceride and generating excess NEFAs. During pancreatitis, obese PNLIP-knockout mice, unlike obese adipocyte-specific ATGL knockouts, had lower visceral adipose tissue lipolysis, milder inflammation, less severe organ failure, and improved survival. PNLIP-knockout mice, unlike ATGL knockouts, were protected from adipocyte-induced pancreatic acinar injury without affecting NEFA signaling or acute pancreatitis induction. Therefore, during pancreatitis, unlike diverticulitis, PNLIP leaking into visceral adipose tissue can cause excessive visceral adipose tissue lipolysis independently of adipocyte-autonomous ATGL, and thereby worsen organ failure.

Not only fat: omental infarction and its mimics in children. Clinical and ultrasound findings: a pictorial review

Acute abdominal pain in children is the most common cause of emergency department admissions. Omental infarction is a rare cause of acute abdominal pain in this age group, accounting for approximately 15% of cases in children and 0.024-0.1% of cases of surgery for suspected appendicitis at the same age. Its clinical presentation may mimic similar diseases such as acute appendicitis, epiploic appendagitis, and mesenteric panniculitis. Ultrasound is the modality of choice for the initial evaluation of acute abdominal pain in pediatric patients and it can be used with confidence in the diagnosis and management of omental infarction in children. In this brief review, we focus on the main ultrasound findings and their diagnostic clue for omental infarction and its mimics.

Non-neoplastic conditions mimicking peritoneal carcinomatosis at CT imaging

The general appearance of peritoneal carcinomatosis at abdominal CT and other cross-sectional imaging modalities consists of varying amounts of peritoneal-based soft tissue implants (mass-forming or infiltrative), peritoneal fluid, and occasionally calcification. However, a wide variety of common and uncommon neoplastic and non-neoplastic conditions can closely mimic peritoneal carcinomatosis at imaging. Neoplastic mimics of peritoneal carcinomatosis include primary peritoneal and sub peritoneal tumors, as well as peritoneal lymphomatosis and sarcomatosis.Broad categories of non-neoplastic mimics of peritoneal carcinomatosis include tumor-like conditions, systemic processes, atypical infections, and fat-based conditions. For many entities, suggestive or specific patient information and/or CT imaging findings exist that may allow the radiologist to narrow the differential diagnosis. In this article, we review the salient clinical and cross-sectional imaging features of non-neoplastic mimics of peritoneal carcinomatosis and malignancy, with emphasis on the CT findings and the additional clues that may suggest the correct benign diagnosis.

"Tethered Fat Sign": The Sonographic Sign of Omental Infarction

Our purpose is to describe the ultrasound sign for a correct non-invasive diagnosis of omental infarction in children. From January 2014 to December 2018, a total of 234 children (109 boys and 125 girls, age range 3-15 y) with acute right-sided abdominal pain, admitted to our hospital with a presumptive diagnosis of acute appendicitis, were prospectively evaluated. In all patients, abdominal ultrasound was performed, and the omental fat was always evaluated. In 228 patients, the omental fat resulted to be normal or hyperechogenic, never tethered, and they results affected by other causes of abdominal pain different from omental infarction (such as appendicitis, pancreatitis, urolithiasis and others). In the remaining 6 children, we found a hyperechoic mass between the anterior abdominal wall and the ascending or transverse colon in the right abdomen quadrant, suggesting the diagnosis of omental infarction. This subhepatic mass was always tethered to the abdominal wall, motionless during respiratory excursions. We named this finding the "tethered fat sign." The diagnosis was confirmed with laparoscopy in 4 children. The other 2 children were treated with conservative therapy. In these 2 patients, a sonographic follow-up was performed, showing a progressive reduction in size of the right-sided hyperechoic mass. In conclusion, our study suggests that the presence of the "tethered fat sign" may be an accurate sonographic sign for non-invasive diagnosis of omental infarction in children.

Idiopathic segmental infarction of the omentum mimicking acute appendicitis: A case report

INTRODUCTION

Omentum is a well vascularized organ. Omentum infarction is uncommon. Most of the cases are secondary due to torsion, intra-abdominal infections and vascular thrombosis. Primary idiopathic segmental omental infarction is rare.

PRESENTATION OF CASE

A 26-year-old male presented with acute onset right iliac fossa pain mimicking acute appendicitis. On radiological imaging, early acute appendicitis was suspected. On diagnostic laparoscopy, appendix appeared normal and there was idiopathic infarction of a part of the greater omentum lying close to the cecum. Patient underwent laparoscopic appendectomy with excision of the diseased segment of the omentum and had uneventful recovery.

CONCLUSION

Idiopathic omental infarction should be included in the differential diagnoses while treating patient with acute abdomen.

CT imaging findings of epiploic appendagitis: an unusual cause of abdominal pain

Epiploic appendagitis is a rare cause of acute abdominal pain, determined by a benign self-limiting inflammation of the epiploic appendages. It may manifest with heterogeneous clinical presentations, mimicking other more severe entities responsible of acute abdominal pain, such as acute diverticulitis or appendicitis. Given its importance as clinical mimicker, imaging plays a crucial role to avoid inaccurate diagnosis that may lead to unnecessary hospitalization, antibiotic therapy, and surgery. CT represents the gold standard technique for the evaluation of patients with indeterminate acute abdominal pain. Imaging findings include the presence of an oval lesion with fat-attenuation surrounded by a thin hyperdense rim on CT (“hyperattenuating ring sign”) abutting anteriorly the large bowel, usually associated with inflammation of the adjacent mesentery. A central high-attenuation focus within the fatty lesion (“central dot sign”) can sometimes be observed and is indicative of a central thrombosed vein within the inflamed epiploic appendage. Rarely, epiploic appendagitis may be located within a hernia sac or attached to the vermiform appendix. Chronically infarcted epiploic appendage may detach, appearing as an intraperitoneal loose calcified body in the abdominal cavity. In this review, we aim to provide an overview of the clinical presentation and key imaging features that may help the radiologist to make an accurate diagnosis and guide the clinical management of those patients.

Utilization of Imaging to Identify a Benign Condition Mimicking Acute Appendicitis in a Child

One of the most concerning causes of abdominal pain affecting children is acute appendicitis. However, there are benign conditions that can closely mimic appendicitis in children. In this article, we present a case of a child admitted for possible acute appendicitis and determined to have a condition known as omental infarction. The patient was managed medically and made a full recovery without surgical intervention. The aim of this case report is to review omental infarction and present a way of differentiating this disease from appendicitis, utilizing imaging, with the goal of avoiding surgical intervention. We also discuss the presentation and imaging findings of and another closely related condition—epiploic appendagitis. It is important to differentiate appendicitis from these 2 conditions as they can be often managed medically without surgical intervention.

Left-sided omental infarction: a rare cause of abdominal pain, discovered by CT scan

Omental infarction in adults is a rarely occurring phenomenon, with left-sided omental infarction being even more seldom. The importance of this case report lies in raising awareness of the diagnosis omental infarction as a cause of acute abdomen among doctors who work in the emergency department, in order to prevent unnecessary surgical interventions as conservative treatment generally solves the problem. Omental infarction is the result of vascular obstruction and ends in tissue ischaemia. Because of the rich vasculature of the greater omentum, anastomoses reorganise the vascularisation, which explains the mostly benign course of omental infarction. By adding omental infarction to the list of differential diagnoses in patients who present with acute abdominal pain, future management of patients with an acute abdomen can be adjusted for the optimal approach to not overlook any surgery-requiring diagnosis as well as to prevent overtreatment.

Imaging of the pediatric peritoneum, mesentery and omentum

The normal peritoneal structures, including the mesenteries and the omenta, are only a few cell layers thick and are visible on imaging based upon the tissues (e.g., fat) and structures (e.g., blood vessels and lymph nodes) contained within them. These structures become more visible and change in appearance when involved by pathological processes. In this pictorial essay, we discuss the normal anatomy of the various abdominopelvic peritoneal structures and illustrate numerous developmental and acquired diagnoses that involve these structures in the pediatric and young adult population.