Celiac Disease-Related Changes
Celiac disease is an immune reaction to gluten that damages the lining of the small intestine, and that damage produces a set of findings visible on abdominal imaging. Because celiac disease is diagnosed by blood tests and biopsy rather than by scans, these imaging changes are rarely the reason a diagnosis is made deliberately—but they are sometimes the first clue, appearing on a CT ordered for abdominal pain, bloating, or unexplained weight loss in someone whose celiac disease has not yet been recognized. The findings range from subtle and nonspecific to reasonably characteristic, and understanding them matters in two directions: they can prompt appropriate testing in an undiagnosed patient, and they can help identify the uncommon but serious complications that develop in longstanding or poorly controlled disease.
What is it?
The small intestine absorbs nutrients across a lining folded into countless finger-like projections called villi, which together create an enormous absorptive surface area. In celiac disease, gluten—a protein found in wheat, barley, and rye—triggers an immune response in genetically susceptible people that damages this lining. The villi flatten and are lost, a process called villous atrophy, while the crypts between them lengthen and inflammatory cells accumulate. The result is a smoother, less absorptive surface, and the consequences of that reduced absorption account for most of the condition’s effects.
Celiac disease is an autoimmune condition rather than an allergy or an intolerance. It requires specific genetic background—essentially all patients carry HLA-DQ2 or HLA-DQ8—though these genes are common in the general population and most carriers never develop the disease, so genetic testing is useful mainly for ruling the condition out rather than confirming it.
Damage is typically most severe in the duodenum and proximal jejunum, where gluten concentration is highest, and diminishes further along the small intestine. This proximal predominance explains one of the more distinctive imaging findings.
The imaging changes associated with celiac disease can be grouped by what they reflect.
Reversal of the small bowel fold pattern is the most characteristic finding. Normally the jejunum, in the upper small intestine, has numerous closely spaced circular folds, while the ileum further along has fewer. In celiac disease, damage to the proximal bowel reduces jejunal folds while the ileum may develop compensatory changes with increased folds—producing a reversed pattern, sometimes described as jejunoileal fold reversal. This is among the more specific findings, though it is not present in every patient.
Small bowel dilatation with increased intraluminal fluid is common, reflecting impaired absorption leaving more fluid in the lumen. Loops appear distended and fluid-filled without any obstruction.
Small bowel wall thickening may be present, usually mild, and is nonspecific on its own.
Mesenteric lymphadenopathy is frequently seen, typically as multiple mildly enlarged nodes in the small bowel mesentery. This is usually a benign reactive finding in celiac disease, though it is also one that can prompt concern about lymphoma when the underlying diagnosis is not known.
Increased prominence and engorgement of the mesenteric vessels—sometimes described as a comb-like appearance of the vasa recta—reflects increased blood flow to inflamed bowel.
Transient small bowel intussusception is a recognized association. These are typically short-segment, non-obstructing, and self-resolving, and are increasingly identified incidentally on CT. Their presence in an adult without an obvious lead point is one of the situations where testing for celiac disease is reasonable.
Two findings deserve particular attention because they signal something beyond uncomplicated disease.
Cavitating mesenteric lymph node syndrome is a rare but important finding, in which mesenteric lymph nodes develop low-density or fluid-like centres. It is associated with severe disease, splenic atrophy, and a poorer prognosis, and warrants specialist assessment.
Splenic atrophy—a small spleen, sometimes with functional hyposplenism—occurs in a proportion of patients with celiac disease. Its practical importance is that reduced spleen function increases susceptibility to certain bacterial infections, which is why pneumococcal vaccination is recommended.
Other associated findings include fatty liver, and features reflecting nutritional consequences such as reduced bone density.
An important limitation must be stated clearly: none of these findings is sufficient to diagnose celiac disease, and their absence does not exclude it. Many patients with celiac disease have entirely normal abdominal imaging. The findings are also individually nonspecific, overlapping with infection, inflammatory bowel disease, small bowel bacterial overgrowth, and other causes of malabsorption. Their value lies in prompting appropriate testing when they appear in a suggestive clinical context, not in replacing that testing.
The clinical presentation of celiac disease is far broader than commonly assumed, and this breadth is the main reason so many cases go undiagnosed for years.
The classical picture—chronic diarrhoea, bloating, wind, abdominal pain, weight loss, and fatty stools that are pale, bulky, and difficult to flush—is now recognized as only one presentation, and in adults not the most common.
Non-digestive presentations are frequent and often dominate. Iron deficiency anaemia that fails to respond to oral supplementation is a classic example, since iron absorption occurs in the very part of the bowel most affected. Persistent fatigue is common. Reduced bone density, osteoporosis, and unexplained fractures follow from impaired calcium and vitamin D absorption. Mouth ulcers and dental enamel defects occur. Unexplained elevation of liver enzymes is a recognized presentation. Neurological features including peripheral neuropathy, headache, and ataxia occur in a minority. Reproductive effects include infertility, recurrent miscarriage, and delayed puberty.
Dermatitis herpetiformis is a specific skin manifestation—an intensely itchy blistering rash, typically symmetrical over the elbows, knees, buttocks, and scalp. It represents celiac disease expressed in the skin, responds to a gluten-free diet, and its presence effectively establishes the diagnosis.
In children, faltering growth, short stature, delayed puberty, irritability, and abdominal distension are common, and digestive symptoms are more prominent than in adults.
Certain groups warrant testing even without symptoms because of markedly elevated risk: first-degree relatives of people with celiac disease, and people with type 1 diabetes, autoimmune thyroid disease, autoimmune liver disease, Down syndrome, Turner syndrome, Williams syndrome, and selective IgA deficiency.
Diagnosis follows a defined pathway that imaging supports rather than leads.
Serological testing is the first step. Tissue transglutaminase IgA antibody is the primary test, measured alongside total IgA because selective IgA deficiency—more common in celiac disease than in the general population—produces false negative results. Where IgA is deficient, IgG-based tests are used instead. Endomysial antibody testing is highly specific and used for confirmation in some pathways.
The most important practical point about testing is that it must be performed while the patient is still eating gluten. Both antibody levels and intestinal damage normalize on a gluten-free diet, so someone who has already stopped eating gluten may test negative despite genuinely having the condition. Patients who suspect celiac disease should be tested before changing their diet, and those who have already changed it may need a supervised gluten challenge—which is unpleasant and is a strong argument for testing first.
Upper endoscopy with multiple duodenal biopsies remains the diagnostic standard in adults. Multiple samples are taken, including from the duodenal bulb, because damage can be patchy. Findings are graded by the degree of villous atrophy, crypt lengthening, and inflammatory cell infiltration.
In children, guidelines in some regions allow diagnosis without biopsy when antibody levels are very high and specific confirmatory criteria are met.
Genetic testing for HLA-DQ2 and DQ8 has high negative predictive value: if neither is present, celiac disease is effectively excluded. A positive result is far less useful, since these genes are common.
CT and MR enterography demonstrate the imaging findings described above and are used principally when complications are suspected or when symptoms persist despite treatment, rather than for initial diagnosis. MR enterography avoids radiation, which matters in a young population likely to need repeated assessment.
Capsule endoscopy visualizes the small bowel lining directly and is used to assess the extent of involvement and to look for ulceration, strictures, or masses in patients with persistent symptoms.
Blood tests beyond serology assess consequences: complete blood count, iron studies, ferritin, folate, vitamin B12, vitamin D, calcium, liver function, and thyroid function.
Important to Know
A strict, lifelong gluten-free diet remains the only established treatment for celiac disease, and adherence determines both symptom control and the reversal of intestinal and imaging changes. Care is typically coordinated by gastroenterologists and specialist dietitians, with primary care involvement for long-term monitoring.
The diet requires eliminating wheat, barley, and rye and everything derived from them. Oats are tolerated by most people with celiac disease but must be certified gluten-free because of cross-contamination during processing, and a small minority react to oats themselves. Cross-contamination in shared kitchens, from shared toasters, chopping boards, and fryers, is a common and underappreciated source of ongoing exposure. Dietitian input substantially improves both adherence and nutritional quality, since gluten-free processed foods are often lower in fibre and fortified nutrients.
Recovery follows a predictable but sometimes frustrating timeline. Symptoms typically improve within weeks. Antibody levels fall over months. Healing of the intestinal lining takes considerably longer—often one to two years in adults, and sometimes longer still, with a proportion of adults never achieving complete histological recovery despite good adherence. Imaging findings likewise improve over months rather than weeks. Understanding this sequence prevents unnecessary concern when symptoms have improved but a follow-up test has not yet fully normalized.
Nutritional deficiencies are corrected and monitored. Iron, folate, vitamin B12, vitamin D, calcium, and zinc are commonly affected. Bone density assessment is recommended for adults at diagnosis, since reduced bone density is common and often silent, and is reassessed according to the initial result and risk factors.
Pneumococcal vaccination is recommended because of the reduced splenic function that occurs in a proportion of patients.
Ongoing monitoring typically includes periodic review of symptoms, dietary adherence, antibody levels, and nutritional status. Repeat biopsy is performed selectively rather than routinely, most often when symptoms persist.
Persistent symptoms despite a gluten-free diet require systematic reassessment rather than assumption of dietary failure. The most common explanation by a wide margin is continued gluten exposure, often inadvertent, and a detailed dietary review with a specialist dietitian is the appropriate first step. Other explanations include coexisting conditions that are more common in celiac disease—lactose intolerance, small intestinal bacterial overgrowth, microscopic colitis, pancreatic insufficiency, and irritable bowel syndrome—and incorrect original diagnosis.
Refractory celiac disease is the uncommon situation where symptoms and intestinal damage persist despite a genuinely strict diet for a sustained period. It is divided into two types based on the characteristics of the intestinal lymphocytes, with type 2 carrying a substantially worse prognosis and a meaningful risk of progression to lymphoma. It requires specialist management at centres with expertise.
The complications of longstanding or poorly controlled celiac disease are uncommon but are the reason imaging retains a role. Enteropathy-associated T-cell lymphoma is a rare but serious complication, more likely in older patients, those diagnosed late, and those with refractory disease or poor adherence. Small bowel adenocarcinoma occurs at increased frequency. Ulcerative jejunitis produces ulceration, bleeding, stricture, and occasionally perforation. New or changing symptoms in someone with established celiac disease—particularly weight loss, abdominal pain, obstruction, bleeding, or systemic symptoms—warrant investigation rather than attribution to dietary lapses. Importantly, the risk of these complications is substantially reduced by good dietary adherence, which is one of the strongest practical arguments for strictness.
A note on self-diagnosis and elimination diets is worth including. Because gluten avoidance has become widespread, many people begin a gluten-free diet without testing. This makes subsequent diagnosis considerably harder and can obscure a condition with real long-term health consequences that requires lifelong management, monitoring, and family screening. Non-celiac gluten sensitivity is a distinct entity in which symptoms respond to gluten avoidance without the immune damage or complications of celiac disease, and distinguishing the two matters. Anyone considering removing gluten from their diet is better served by testing first.
Family members deserve mention: first-degree relatives have roughly a one in ten risk, considerably higher than the general population, and testing is appropriate for symptomatic relatives and is often offered to asymptomatic ones as well.
Care is typically coordinated by gastroenterology and dietetics, with primary care, endocrinology, and haematology involvement as needed. Imaging, laboratory, endoscopic, and clinical findings are interpreted together alongside the patient’s symptoms and dietary history rather than in isolation.
Patient education plays an important role. Understanding that imaging findings support but do not establish the diagnosis, that testing must be done before removing gluten from the diet, that intestinal healing lags well behind symptom improvement, that strict adherence reduces long-term complication risk rather than merely controlling symptoms, and which new symptoms warrant investigation all contribute to appropriate care.
Red flag symptoms include unintentional weight loss, particularly in someone with established celiac disease on a strict diet; persistent or worsening abdominal pain; crampy pain with vomiting, distension, and inability to pass gas or stool; rectal bleeding or black tarry stools; fever, drenching night sweats, or a palpable abdominal mass; progressive fatigue with worsening anaemia; new diarrhoea after a period of good control; and any significant change in symptoms after years of stable disease. These warrant prompt medical evaluation, as they may indicate refractory disease, ulcerative jejunitis, stricture, lymphoma, or another complication.