Epiploic appendagitis

INTRODUCTION — Epiploic appendages are normal outpouchings of peritoneal fat on the anti-mesenteric surface of the colon. Epiploic appendagitis is a benign and self-limited condition [1,2]. Inaccurate diagnosis can lead to unnecessary hospitalizations, antibiotic therapy, and surgical intervention [3-6]. This topic will review the clinical manifestations, diagnosis, and management of epiploic appendagitis.

DEFINITION — Epiploic appendagitis is an ischemic infarction of an epiploic appendage caused by torsion or spontaneous thrombosis of the epiploic appendage central draining vein.

EPIDEMIOLOGY — The true incidence of epiploic appendagitis is not known. However, epiploic appendagitis has been reported in 2 to 7 percent of patients who were initially suspected of having acute diverticulitis and in 0.3 to 1 percent of patients suspected of having acute appendicitis [7]. Epiploic appendagitis occurs most commonly in the second to fifth decades of life with a mean age at diagnosis of 40 years. The incidence of epiploic appendagitis has been reported to be up to four times higher in men as compared with women [7-9]. Epiploic appendagitis can arise in any segment of the colon. In surgical case series, 57 percent of cases occur in the rectosigmoid, 26 percent in the ileocecum, 9 percent in the ascending colon, 6 percent in the transverse colon, and 2 percent in the descending colon [7,10,11]. Obesity, an increase in abdominal adipose tissue, and strenuous exercise may be risk factors for the development of epiploic appendagitis [7,11,12].

ANATOMY — Epiploic appendages are small outpouchings of fat-filled, serosa-covered structures present on the external surface of the colon projecting into the peritoneal cavity. Each appendage encloses small branches of the circular artery and vein that supply the corresponding segment of the colon. Subserosal lymphatic channels either terminate in a lymph node within an appendage or loop through its base en route to mesenteric nodes.

On average, the adult colon has approximately 50 to 100 appendages. Epiploic appendages occur all along the entire colon but are more abundant and larger in the transverse and sigmoid colon. They are usually rudimentary at the base of the appendix [1,13]. The appendages vary considerably in size, shape, and contour. Most epiploic appendages are 1 to 2 cm thick and 2 to 5 cm long, although they are occasionally up to 15 cm [14]. For unclear reasons, they are largest and most prominent in obese persons and in those who have recently lost weight [1,15]. Although the exact role of epiploic appendages is not known, they are presumed to serve a protective and defensive mechanism similar to that offered by the greater omentum and may have a role in colonic absorption. They may also act as a cushion, protecting colonic blood supply during peristalsis [1].

PATHOGENESIS — Epiploic appendagitis is usually caused by torsion, which occurs when the appendage is abnormally long and large. The vein, which is longer than the artery by virtue of its tortuous course, alters the anatomy such that the pedicle is predisposed to twisting. Acute torsion causes ischemia and infarction with aseptic fat necrosis and spontaneous venous thrombosis. Spontaneous venous thrombosis of a draining vein can also predispose to twisting of the appendage pedicle. Gradual torsion of the appendages can result in chronic inflammation with minimal or no symptoms. By contrast, acute strangulation is associated with the development of symptoms.

CLINICAL MANIFESTATIONS

Clinical presentation — Patients with epiploic appendagitis most commonly present with acute or subacute onset of lower abdominal pain. The pain is in the left abdomen in 60 to 80 percent of patients but has also been reported in the right lower quadrant. The pain is often described as a constant, dull, localized pain that does not radiate [16]. Other less frequent symptoms include postprandial fullness, early satiety, vomiting, bloating, diarrhea, and low-grade fever.

On physical examination, patients usually do not appear to be seriously ill and are usually afebrile. The pain is localized to the affected area, and rebound tenderness is usually absent [17]. A mass is palpable in 10 to 30 percent of patients [18].

Laboratory findings — The white blood count, erythrocyte sedimentation rate, and C-reactive protein are usually normal but may be mildly elevated [11,19].

DIAGNOSIS — Epiploic appendagitis is usually diagnosed incidentally in patients undergoing imaging for acute/subacute onset of lower abdominal pain [3,20,21]. The diagnosis should also be considered when exploration of the abdomen fails to reveal any of the more common causes of acute abdominal pain. Abdominal computed tomography (CT) is diagnostic for epiploic appendagitis while excluding other causes of abdominal pain. We reserve the use of abdominal ultrasonography to diagnose epiploic appendagitis when CT scan findings are equivocal or if CT scan is not readily available. Abdominal ultrasound is best suited for patients with a thin body habitus seen when performed at centers with experience in sonographic imaging of the colon.

Abdominal computed tomography scan — The classic finding of epiploic appendagitis is a 2 to 3 cm, oval-shaped, fat density, paracolic mass with thickened peritoneal lining and periappendageal fat stranding (image 1) [11,21-26]. A high-attenuated central dot within the inflamed appendage that corresponds to a thrombosed draining appendageal vein is occasionally evident [5,11]. The fat density ovoid lesion and the central high attenuation focus within the fatty lesion are also known as the ring sign and the dot sign, respectively [27]. In the absence of inflammation, epiploic appendices are usually not seen on CT scan unless they are surrounded by a sufficient amount of intraperitoneal fluid (eg, ascites or hemoperitoneum) or inflammation. Magnetic resonance imaging (MRI) findings of epiploic appendagitis have not been well studied but appear to correlate with CT findings [28].

Abdominal ultrasound — On abdominal ultrasound, the inflamed appendage appears as a noncompressible, solid, hyperechoic ovoid mass with a subtle hypoechoic rim located at the point of maximal tenderness [11]. The inflamed fatty mass is fixed to the colon and often also to the parietal peritoneum during inspiration and expiration. Doppler studies typically reveal absence of blood flow in the appendage and normal blood flow in the hyperechoic inflamed fat surrounding the appendage [24,29-31]. Contrast-enhanced ultrasound shows a central area of no enhancement with moderately increased vascularization around the avascular necrotic appendage [32]. (See "Transabdominal ultrasonography of the small and large intestine".)

DIFFERENTIAL DIAGNOSIS — The differential diagnosis of epiploic appendagitis consists of other causes of acute onset of lower abdominal pain (table 1) [33]. Of these, epiploic appendagitis is most often confused with acute diverticulitis and acute appendicitis. These conditions can usually be differentiated by the clinical presentation and by abdominal imaging (eg, abdominal computed tomography [CT] scan). (See "Evaluation of the adult with abdominal pain", section on 'Lower abdominal pain'.)

●Acute uncomplicated diverticulitis – Patients with acute uncomplicated diverticulitis may present with abdominal pain and a small percentage of patients may have diarrhea. On imaging, patients with acute uncomplicated diverticulitis have colonic thickening and paracolic fat stranding in the area of the colon with diverticula.

●Acute appendicitis – The classic symptoms of appendicitis include right lower quadrant abdominal pain, anorexia, fever, nausea, and vomiting. Abdominal CT scan findings of acute appendicitis include an enlarged appendiceal diameter >6 mm with an occluded lumen, appendiceal wall thickening (>2 mm), periappendiceal fat stranding, appendiceal wall enhancement.

MANAGEMENT — There are limited data from case reports to guide the management of patients with epiploic appendagitis.

Conservative management — Patients can be managed conservatively with oral anti-inflammatory medications (eg, ibuprofen 600 mg orally every eight hours for four to six days) and if needed a short course of opioids (acetaminophen/codeine 300/30 every six hours) for four to seven days [11,34-37]. Anti-inflammatories provide analgesia but probably do not modify the disease course. Patients usually do not require hospitalization or antibiotics [38]. (See 'Natural history and disease course' below.)

Surgery — We reserve surgical management for patients whose symptoms fail to improve with conservative management, those with new or worsening symptoms (eg, high fever, progressive pain, nausea, vomiting, or inability to tolerate an oral diet), or complications (eg, intussusception, bowel obstruction, abscess) that cannot be managed nonoperatively. The inflamed appendage should be ligated and resected [39].

NATURAL HISTORY AND DISEASE COURSE

Epiploic appendagitis is a benign and self-limiting condition. Complete resolution without surgical intervention usually occurs between 3 to 14 days [11,29,34,35]. The risk of recurrence has not been described but is probably very low. Rarely, inflamed appendages can adhere to the abdominal wall or other viscera predisposing to intestinal obstruction and intussusception [40]. Inflamed and necrotic appendages can also rarely progress to abscess formation.

There are other less common conditions affecting the epiploic appendices. They can slide into a femoral, umbilical, or inguinal hernia sac where they may remain without causing symptoms or (less commonly) incarcerate with or without torsion [13,41]. The appendices can also calcify, cast off, and lie free as foreign bodies (corpora aliena) in the peritoneal cavity or become surrounded by omental adhesions [20]. Epiploic appendages are thought to represent the most frequent source of intraperitoneal loose bodies, which are usually found in the pelvis [42]. These may become secondarily attached elsewhere in the abdomen and can be confused with a neoplastic process.

SUMMARY AND RECOMMENDATIONS

●Epiploic appendagitis, also known as appendicitis epiploica, hemorrhagic epiploitis, epiplopericolitis, or appendagitis, is an ischemic infarction of an epiploic appendage caused by torsion or spontaneous thrombosis of the epiploic appendage central draining vein. (See 'Definition' above.)

●The incidence of epiploic appendagitis is not known. However, epiploic appendagitis has been reported in 2 to 7 percent of patients who were suspected of having diverticulitis and in 0.3 to 1 percent of patients suspected of having appendicitis. Epiploic appendagitis occurs most commonly in the second to fifth decades of life with a mean age at diagnosis of 40 years. The incidence of epiploic appendagitis is up to four times higher in men as compared with women. Obesity and strenuous exercise may be risk factors for the development of epiploic appendagitis. (See 'Epidemiology' above.)

●Epiploic appendagitis is usually caused by acute torsion, which occurs when the appendage is abnormally long and large. Acute torsion causes ischemia and infarction with aseptic fat necrosis and spontaneous venous thrombosis. Gradual torsion of the appendages can result in chronic inflammation with minimal or no symptoms. (See 'Pathogenesis' above.)

●Patients most commonly present with acute or subacute lower abdominal pain. Less frequent symptoms include postprandial fullness, early satiety, vomiting, bloating, diarrhea, and low-grade fever. The white blood count with differential, erythrocyte sedimentation rate, and C-reactive protein are normal or mildly elevated. (See 'Clinical manifestations' above.)

●The differential diagnosis of epiploic appendagitis consists of other causes of acute onset of lower abdominal pain (table 1). Of these, epiploic appendagitis is most often confused with acute diverticulitis and acute appendicitis. These conditions can usually be differentiated by the clinical presentation and by abdominal imaging (eg, abdominal computed tomography [CT] scan). (See 'Differential diagnosis' above.)

●Epiploic appendagitis is usually diagnosed incidentally in patients undergoing imaging for acute onset of lower abdominal pain. Abdominal CT scan is diagnostic. The classic finding is a 2 to 3 cm, oval-shaped, fat density, paracolic mass with thickened peritoneal lining and periappendageal fat stranding (image 1) [11,21-26]. A high-attenuated central dot within the inflamed appendage that corresponds to a thrombosed draining appendageal vein is occasionally evident. (See 'Diagnosis' above.)

●We recommend initial conservative management rather than surgery in patients with epiploic appendagitis confirmed by abdominal imaging (Grade 1C). We typically treat patients with oral anti-inflammatory medications (eg, ibuprofen 600 mg PO every eight hours for four to six days) and if needed a short course of opiates (acetaminophen/codeine 300/30 every six hours) for four to seven days. We reserve surgical management for patients whose symptoms fail to improve with conservative management, those with new or worsening symptoms (eg, high fever, progressive pain, nausea, vomiting, or inability to tolerate an oral diet), or complications (eg, intussusception, bowel obstruction, abscess) that cannot be managed nonoperatively. (See 'Management' above.)

●Epiploic appendagitis is a benign and self-limiting condition. Complete resolution without surgical intervention usually occurs between 3 to 14 days. Complications (eg, intussusception, bowel obstruction, abscess) are rare. (See 'Natural history and disease course' above.)