Appendices epiploicae are small, finger-like pouches of fat that hang from the outer surface of your large intestine, and most people go their entire lives without knowing they exist. Numbering somewhere between 50 and 100 per person, these peritoneum-covered fat tags line the colon from the cecum all the way down to the upper rectum. They are clinically invisible until something goes wrong, at which point they can produce sharp abdominal pain that gets mistaken for far more serious conditions like diverticulitis or appendicitis.
What They Look Like and Where They Sit
Each appendix epiploica is a small protrusion of fat wrapped in a thin layer of peritoneum, the membrane that lines your abdominal cavity. They dangle from the colon’s outer wall, attached by narrow stalks that contain small blood vessels. Their size varies, but most are a few centimeters long, roughly the size of a grape or olive. They tend to be largest and most numerous along the sigmoid colon (the S-shaped portion of the large intestine in your lower left abdomen) and the cecum (the pouch where your small and large intestines meet on the lower right). They run along two bands of muscle on the colon wall, arranged in rows like small ornaments hanging off a garland.
The narrow stalk connecting each appendix to the colon is an important detail. That thin attachment point means the blood supply feeding each pouch is limited and vulnerable. A small twist or a clot can cut off circulation entirely, which is the root cause of nearly every clinical problem these structures create.
What They Actually Do
Nobody is entirely sure. That might seem surprising for a structure found in every human being, but their function has genuinely eluded researchers for decades. The earliest surgical literature suggested they serve as fat storage depots and provide cushioning for the colon as it handles increasingly solid contents.1JAMA Surgery. Surgical Significance of Epiploic Appendages More recent work has added a few other candidates to the list: they may act as a blood reservoir for the colon, contribute to local immune defense, and play some role in colonic absorption. But the honest scientific answer is that no one has pinned down a definitive purpose.2PubMed Central. Epiploic Appendagitis: An Often Misdiagnosed Cause of Acute Abdomen
This uncertainty is part of what makes them an overlooked structure. They are not mentioned in most anatomy courses beyond a brief aside, and because they are clinically silent in healthy people, they simply do not get much research attention. The interest that does exist comes almost entirely from what happens when they go wrong.
Epiploic Appendagitis and Why It Happens
Epiploic appendagitis is the inflammation of one of these fat pouches, and it is almost always caused by a loss of blood flow. The narrow stalk can twist on itself, or the small vein running through its center can develop a spontaneous blood clot. Either way, the result is the same: the tissue loses its blood supply, becomes ischemic, and begins to inflame or die.3PubMed. Epiploic appendagitis: an entity frequently unknown to clinicians–diagnostic imaging, pitfalls, and look-alikes Think of it as a small, localized infarction of fat on the surface of your colon.
The condition is considered self-limiting, meaning it resolves on its own in most people without any specific intervention beyond pain management. But before it resolves, it can cause sharp, localized belly pain that sends people to the emergency room convinced something serious is happening. And because many emergency physicians and even some radiologists are unfamiliar with the condition, it is frequently diagnosed as something else.
Who Gets It
Epiploic appendagitis is not common, but it is not as rare as textbooks suggest, either. The people who tend to get it share a few characteristics. It occurs more often in men, and the average age at diagnosis is around 50, though it can happen at any age.4PubMed. Epiploic appendagitis: 7-year experience and relationship with visceral obesity In one study, about two thirds of patients were male.
The strongest association is with visceral obesity, meaning excess fat stored around the abdominal organs rather than just under the skin. A retrospective study found that patients who developed epiploic appendagitis had roughly 60 percent more abdominal fat volume and more than double the visceral fat area compared to matched controls.5Exploration of Endocrine and Metabolic Diseases. Epiploic appendagitis during rapid weight loss associated with tirzepatide therapy: a case report Other risk factors that have been identified include high blood pressure, diabetes, strenuous exercise, and the presence of abdominal hernias. The connection to visceral fat makes intuitive sense: larger, heavier fat pouches on a thinner stalk are more prone to twisting or having their blood supply compromised.
An interesting recent observation is that rapid weight loss may also be a trigger. Case reports have emerged linking the condition to patients using newer weight-loss medications, possibly because rapid changes in abdominal fat distribution can destabilize these structures in ways that are still being studied.
What the Pain Feels Like
The hallmark symptom is sudden, sharp, well-localized abdominal pain. It usually comes on quickly, feels like it is in one specific spot rather than spread across the belly, and does not radiate elsewhere. The most common location is the lower left side of the abdomen, because the sigmoid colon is where appendices epiploicae are most abundant and largest. But it can also occur on the right side or in the upper abdomen.6Radiology Case Reports. Epiploic appendagitis – a rare cause of acute lower abdominal pain
Other symptoms like nausea, mild fever, bloating, and changes in bowel habits can show up, but they are inconsistent. The pain itself is the main event. One useful distinguishing feature is that blood work is typically normal or only mildly abnormal. White blood cell counts and inflammatory markers tend to stay in the normal range or rise only slightly, which is unusual for the more serious conditions this gets confused with.7PubMed Central. Epiploic appendagitis: An overlooked cause of acute abdominal pain
How It Gets Confused with Diverticulitis and Appendicitis
The reason epiploic appendagitis matters clinically is that it mimics conditions that require very different treatment. Left-sided pain gets labeled as diverticulitis. Right-sided pain gets called appendicitis. Both of those diagnoses can lead to antibiotics, hospital admission, or even surgery. Epiploic appendagitis needs none of those things, and misdiagnosis leads to unnecessary hospitalization and overuse of hospital resources.8PubMed. Misdiagnosis of primary epiploic appendagitis
A few clinical clues can help tell them apart before imaging. Researchers have found that patients with left-sided epiploic appendagitis tend to be younger and more overweight than those with left-sided diverticulitis, and their inflammatory markers stay much lower. In one study, the average C-reactive protein level in epiploic appendagitis patients was about 1.2, compared to 8.4 in diverticulitis patients. The average age was about 50 for epiploic appendagitis and over 62 for diverticulitis.9PubMed Central. Primary epiploic appendagitis: compared with diverticulitis and focused on obesity and recurrence Another study comparing these groups found that while 80 percent of diverticulitis patients had elevated white blood cell counts, fewer than 7 percent of those with epiploic appendagitis did.10PubMed Central. Clinical characteristics of primary epiploic appendagitis
In practical terms, the profile of the typical patient offers a useful mental shortcut: if someone under 60 shows up with sharp left-sided belly pain, has a higher body weight, and blood work that looks surprisingly normal for someone in obvious discomfort, epiploic appendagitis deserves serious consideration before jumping to diverticulitis.
What Imaging Shows
CT scanning is the gold standard for diagnosis and produces a distinctive appearance that, once you know what to look for, is hard to miss. The inflamed fat pouch shows up as a small oval mass, usually between 1.5 and 3.5 centimeters across, with the same density as fat on the scan. It sits right next to the outer wall of the colon and is surrounded by a thin bright ring, known as the hyperattenuating ring sign, which represents the inflamed peritoneal lining of the appendage.11PubMed Central. CT imaging findings of epiploic appendagitis: an unusual cause of abdominal pain 12PubMed. Acute epiploic appendagitis and its mimics
Sometimes a bright dot appears in the center of the fatty mass, called the central dot sign. That dot represents the clotted vein that started the whole process. The surrounding fat often looks hazy or streaky from the inflammatory reaction. An important detail is that the colon wall itself remains normal in thickness, which is a key difference from diverticulitis, where the bowel wall is typically thickened and inflamed.
Ultrasound can also pick up the condition, though it is less definitive. The inflamed appendage appears as a bright, well-defined mass stuck to the colon wall, located right under the spot where the patient reports the most pain. A characteristic finding on ultrasound is the complete absence of blood flow within and around the mass on color Doppler, which makes sense given that the whole problem started with a loss of blood supply.13PubMed. Epiploic appendagitis: color Doppler sonographic findings 14PubMed. Primary epiploic appendagitis: US and CT findings Ultrasound is often used first in emergency settings, and if the findings are suggestive, it can spare the patient a CT scan.
Treatment Is Mostly Waiting
The standard treatment is conservative management, which essentially means anti-inflammatory pain medication and time. Most cases resolve within one to two weeks. In one follow-up study, complete resolution was seen in about a third of patients at two weeks and in most of the rest by three months. Only one patient out of ten followed still had residual changes at six months.15PubMed. Primary epiploic appendagitis: reconciling CT and clinical challenges
Antibiotics are not needed because this is an ischemic process, not an infectious one. There is no bacterial invasion to fight. This is another reason why accurate diagnosis matters so much: a patient misdiagnosed with diverticulitis might receive a full course of antibiotics they do not need, along with dietary restrictions and sometimes hospitalization, all of which are unnecessary for epiploic appendagitis.
The trickier question is what to do when the condition comes back. Some patients develop recurrent episodes, and there is no firm consensus on how to handle that. Some clinicians treat each recurrence conservatively, just as they would a first episode. Others argue that recurrent cases warrant surgical removal of the offending appendage, which can now be done laparoscopically.16PubMed Central. A Case of Recurrent Epiploic Appendagitis Treated With Conservative Management
When Surgery Enters the Picture
Surgery is rare and reserved for specific situations. If the pain does not improve with conservative treatment, if imaging shows the lesion getting worse instead of better, or if there is genuine diagnostic uncertainty that cannot be resolved by imaging alone, laparoscopic exploration becomes both a way to confirm the diagnosis and treat the problem in the same procedure.17PubMed Central. Progressive epiploic appendagitis requiring laparoscopic resection following failure of conservative treatment: a case report The surgeon simply removes the infarcted fat pouch and inspects the surrounding bowel to rule out other pathology. Recovery from this kind of minimally invasive procedure is quick.
Historically, before CT scanning became routine, surgery happened far more often because the diagnosis was rarely made preoperatively. A patient with sharp abdominal pain and an equivocal exam would go to the operating room for suspected appendicitis or a perforated diverticulum, and the surgeon would find an infarcted epiploic appendage instead. The widespread availability of CT has dramatically reduced these unnecessary operations.
Complications and Peritoneal Loose Bodies
In the vast majority of cases, epiploic appendagitis heals without complications. But the aftermath of an episode can leave behind something unusual. After the fat pouch infarcts and its blood supply is completely cut off, the dead fatty tissue gradually undergoes a process called saponification, essentially turning into a soap-like calcium deposit. Over time, the stalk connecting it to the colon atrophies and breaks, and the calcified remnant detaches to float freely inside the abdominal cavity. These are called peritoneal loose bodies.18PubMed Central. Unveiling the rarity: A case report of giant peritoneal loose body
Peritoneal loose bodies are almost always harmless and are usually found incidentally during imaging or surgery for something else entirely. They can grow surprisingly large over the years as they accumulate layers of calcium and protein from the peritoneal fluid around them, occasionally reaching the size of a hen’s egg. On imaging, they can be mistaken for tumors or foreign bodies, leading to unnecessary alarm. Knowing that they are a benign consequence of old epiploic appendagitis can save patients from invasive workups.
Rarely, complications are more serious. There are a handful of case reports in which an infarcted epiploic appendage caused a small bowel obstruction, either by adhering to nearby intestine or by acting as a focal point for adhesion formation.19PubMed Central. Epiploic Appendagitis Causing Small Bowel Obstruction: A Pleasant Surprise This is exceptionally uncommon, but it underscores why follow-up imaging is sometimes warranted in atypical or prolonged cases.
Epiploic Appendagitis in Children
Although most published cases involve adults, epiploic appendagitis does occur in children, and it creates a particular diagnostic challenge in younger patients. In kids, the usual differential for sudden abdominal pain includes appendicitis, ovarian torsion, ruptured ovarian cysts, and kidney stones, none of which are treated the same way as a self-limiting inflammatory condition.20Clin Med Rev Case Rep. Primary Epiploic Appendagitis
Right-sided cases in children are especially tricky because they closely mimic acute appendicitis. Case reports describe children taken to the operating room for what was presumed to be appendicitis, only for surgeons to find an infarcted epiploic appendage near the cecum instead.21Journal of Pediatric Surgery Case Reports. Cecal epiploic appendagitis mimicking acute appendicitis in an 8-year-old child: A case report One clue that can help in pediatric cases is the quality of the pain: epiploic appendagitis tends to produce a sharp, steady pain that stays in one spot from the beginning, rather than the classic migratory pattern of appendicitis, where pain starts around the navel and moves to the right lower quadrant over hours.
When pediatric epiploic appendagitis is diagnosed by imaging before surgery, the outcome is excellent. A short course of anti-inflammatory medication resolves the symptoms, and the child avoids an operation they did not need.22International Journal of Pediatrics and Adolescent Medicine. Epiploic appendagitis: Not so unusual cause of paediatric abdominal pain Awareness among pediatric emergency physicians is growing, but it still lags behind adult practice.
Why So Many Doctors Have Never Heard of It
Epiploic appendagitis sits in an awkward corner of medicine. It is too uncommon to make it into the core teaching for most medical students, but it is common enough that most emergency radiologists will see multiple cases over a career. The condition was first described in the surgical literature in the 1950s and remained a surgical curiosity for decades, largely because it could only be confirmed in the operating room. The CT revolution changed everything by making non-invasive diagnosis possible, but the knowledge gap persisted. Many clinicians trained before widespread CT awareness of the diagnosis simply never encountered it, and the teaching did not always filter down.
The consequence is a cycle of under-recognition. When emergency physicians are not thinking about epiploic appendagitis, they do not order imaging with that diagnosis in mind. When radiologists are not expecting to see it, they may describe the findings without naming the condition. The patient gets treated for diverticulitis, improves on their own (because epiploic appendagitis is self-limiting anyway), and the correct diagnosis is never made. The misdiagnosis rate has been a concern in the literature for years, with studies emphasizing that getting the diagnosis right the first time prevents unnecessary hospital stays, antibiotic courses, and follow-up colonoscopies ordered to investigate the presumed diverticular disease.23PubMed. Misdiagnosis of primary epiploic appendagitis
The silver lining is that recognition has improved substantially in recent years, particularly among radiologists. As CT imaging quality has increased and more case series have been published, the distinctive ring sign and central dot sign have become part of the standard teaching for abdominal imaging. For patients, the practical takeaway is that if you have been diagnosed with diverticulitis but your blood work was surprisingly normal and your pain resolved quickly without antibiotics, it may be worth asking whether epiploic appendagitis was considered.