General appearance

The disease most often appears before the age of 40 with nonspecific symptoms of inflammation. Thus, the patient presents with fever, fatigue, abdominal pain and tenderness (often in the right lower quadrant), and diarrhea. In children, retarded growth and development often occur before any other manifestation. As the disease progresses, sequelae such as strictures and fistulae start arising [1] [2], which may result in bowel obstruction.

Intestinal manifestations

The most commonly affected sites in Crohn's disease are the distal small intestine and the proximal colon, although the disease can occur throughout the whole gastrointestinal (GI) tract. Vomiting becomes a frequent symptom in gastroduodenal involvement [3]. Excessive pain, oozing fistulae, and scars characterize a perianal disease. If the colon is affected, there may be the blood in the stool [4].

Extraintestinal manifestations

Numerous extraintestinal manifestations can exist in Crohn's disease [5]. Arthritic and musculoskeletal pain is the most common [6]. Aphthous ulceration of the mouth is also frequent, as is erythema nodosum of the skin. Episcleritis and uveitis are the principal eye presentations. Hepatobiliary problems such as primary sclerosing cholangitis, which also happens in ulcerative colitis, are also common. Gallstones and kidney stones arise presumably because of malabsorption of fats and bile salts. Apart from kidney stones, the urologic complications include enterovesical fistulae and hydronephrosis. Crohn's disease is also characterized by a hypercoagulable state, osteopenia and osteoporosis, and deficiencies in iron, vitamin B12, and folate, which lead to anemia. Other anemic states are also possible, for example owing to gastrointestinal bleeding.

• Weight Loss

  Symptoms include fever, diarrhea, stomach cramps, vomiting, and weight loss. Regional enteritis increases the risk of colorectal cancer and small intestine cancer. It is a type of inflammatory bowel disease (ibd). [icd9data.com]

  Symptoms: Nausea Weight loss Loss of appetite Vomiting (if narrow segments of bowel are obstructed) Jejunoileitis This type of the disease causes areas of inflammation in the jejunum, which is the middle part of your small intestine. [webmd.com]

  Only 25% of Crohn's disease presents with the classic triad of abdominal pain, weight loss, and diarrhoea. Most children with ulcerative colitis have blood in the stool at presentation. [ncbi.nlm.nih.gov]

• Fever

  The disease is characterized by acute exacerbations with diarrhea, abdominal pain, fever, anorexia, intestinal bleeding, and weight loss. [ncbi.nlm.nih.gov]

  Symptoms include fever, diarrhea, stomach cramps, vomiting, and weight loss. Regional enteritis increases the risk of colorectal cancer and small intestine cancer. It is a type of inflammatory bowel disease (ibd). [icd9data.com]

  Rarely, people have fever. Abscesses deep in the rectum may be less painful but may cause fever and pain in the lower abdomen. A doctor's evaluation Rarely computed tomography A doctor can usually see an abscess if it is in the skin around the anus. [merckmanuals.com]

• Fatigue

  A 53-year-old man with Crohn's disease treated with adalimumab was hospitalised with abdominal pain, fatigue, fever and chills. CT scan of the abdomen showed chronic thickening of the terminal ileum and cecum and new-onset ascites. [ncbi.nlm.nih.gov]

  My husband, who has suffer from chronic fatigue himself after being diagnosed with hep c, can’t understand because the illness is… Reply Created with Sketch. reply [inflammatoryboweldisease.net]

  Symptoms of Crohn’s Disease Common symptoms of Crohn's disease include: Diarrhea Abdominal cramps and pain Rectal bleeding Anemia Weight loss Fatigue, weakness Nausea Fever Mouth sores Sores, abscesses in the anal area [upmc.com]

  When symptoms worsen, they typically include one or more of the following: persistent diarrhea, bloody stool, abdominal pain, constipation, loss of appetite, fatigue, and unexpected weight loss. [nyulangone.org]

• Anemia

  Abstract Anemia often complicates the course of Inflammatory Bowel Disease (IBD). Hepcidin, a liver-produced peptide hormone, is a key mediator of anemia of chronic disease (ACD). [doi.org]

  Crohn's disease is also characterized by a hypercoagulable state, osteopenia and osteoporosis, and deficiencies in iron, vitamin B12, and folate, which lead to anemia. [symptoma.com]

  Blood tests may be done to: Check for anemia. Check for a high white blood cell count and sedimentation rate which are signs of swelling (inflammation) in the body. [genome.gov]

• Chills

  A 53-year-old man with Crohn's disease treated with adalimumab was hospitalised with abdominal pain, fatigue, fever and chills. CT scan of the abdomen showed chronic thickening of the terminal ileum and cecum and new-onset ascites. [ncbi.nlm.nih.gov]

  Photo Credit Dolly Faibyshev for The New York Times Work Out and Chill? Cool temperature workouts may be the answer for those who want to exercise without becoming a hot mess. [nytimes.com]

  If you have chills, fever, pain, dizziness, or bloody diarrhea while away, call a doctor immediately. [webmd.com]

  Other signs that require a doctor's attention include fever, shaking chills, and repetitious vomiting. [disabled-world.com]

  Call your doctor immediately if you feel faint or your pulse is abnormal, you have severe abdominal pain, fever or shaking chills, or persistent vomiting. "Crohn's disease can differ for every single person," Balzora said. [livescience.com]

• Clubbed Finger

  Tapered fingertips Tapering fingers [ more ] 0001182 Percent of people who have these symptoms is not available through HPO Alopecia Hair loss 0001596 Clubbing Clubbing of fingers and toes 0001217 Clubbing of fingers Clubbed fingers Clubbing (hands) [rarediseases.info.nih.gov]

• Abdominal Pain

  When the disease is active, signs and symptoms may include: Diarrhea Fever Fatigue Abdominal pain and cramping Blood in your stool Mouth sores Reduced appetite and weight loss Pain or drainage near or around the anus due to inflammation from a tunnel [mayoclinic.com]

  We describe the case of a 51-year-old man presenting with 7 months of right lower quadrant abdominal pain on the background of known Crohn's disease. [ncbi.nlm.nih.gov]

• Diarrhea

  After the second dose, he got worse and started to have bloody diarrhea. [ncbi.nlm.nih.gov]

  Symptoms include fever, diarrhea, stomach cramps, vomiting, and weight loss. Regional enteritis increases the risk of colorectal cancer and small intestine cancer. It is a type of inflammatory bowel disease (ibd). [icd9data.com]

  Day-to-day living is especially difficult if you suffer chronic symptoms like frequent diarrhea, gastrointestinal bleeding, anal tears, or bowel obstructions. Fortunately, treatments for Crohn's disease can make a big difference. [web.archive.org]

  Symptoms: Cramps after meals Fistulas Diarrhea Abdominal pain that can become intense. Crohn's (Granulomatous) Colitis This form of Crohn's disease affects only the colon. [webmd.com]

• Nausea

  We report a case of a 13-year-old Caucasian boy with abdominal pain for 1.5 years associated with nausea, diarrhea, and weight loss of 10 kg. He presented increased C-reactive protein and an increased erythrocyte sedimentation rate. [ncbi.nlm.nih.gov]

  Gallstones can be incredibly painful and cause cramping, indigestion, nausea, vomiting, and pain in either the back or upper-right abdomen. [verywellhealth.com]

  Common side effects of sulfasalazine include: headache nausea abdominal pain diarrhoea If side effects become particularly troublesome, you should tell your GP as the dose used may need to be adjusted. [hse.ie]

  The most common side effects of azathioprine and mercaptopurine are nausea, vomiting, and a general feeling of illness (malaise). [msdmanuals.com]

• Vomiting

  Symptoms include fever, diarrhea, stomach cramps, vomiting, and weight loss. Regional enteritis increases the risk of colorectal cancer and small intestine cancer. It is a type of inflammatory bowel disease (ibd). [icd9data.com]

  It may occur with acute or chronic symptomatology, such as vomiting or postprandial abdominal pain, and it is usually caused by a lack of mesenteric fat pad under conditions of severe weight loss. Crohn's disease can be one of them. [ncbi.nlm.nih.gov]

• Rectal Bleeding

  Diarrhea Rectal bleeding Weight loss Arthritis Skin problems Fever Rectal bleeding may be serious and continuous enough to cause anemia (low red blood count). Children who have Crohn's disease may have delayed development and stunted growth. [genome.gov]

  Other symptoms include rectal bleeding, weight loss, and fever. If you believe you have Crohn’s disease, you should speak with a healthcare provider who can confirm a diagnosis through laboratory tests, examination, imaging, and a colonoscopy. [celiac.org]

  Symptoms of Crohn’s Disease Common symptoms of Crohn's disease include: Diarrhea Abdominal cramps and pain Rectal bleeding Anemia Weight loss Fatigue, weakness Nausea Fever Mouth sores Sores, abscesses in the anal area [upmc.com]

• Aphthous Stomatitis

  Arthritis Erythema nodosum Pyoderma gangrenosum Aphthous stomatitis Iritis/uveitis Table 2 Autoimmune disorders associated to IBD. [doi.org]

  Oral EIMs Aphthous stomatitis (7–21%) and arthritis (8–26%) are among the most common EIMs in children (11,13). Aphthous stomatitis is more common in patients with CD (20–30%) than in those with UC (5–10%) (3). [tp.amegroups.com]

  stomatitis 35 joints arthritis seronegative spondyloarthritis sacroiliitis (one of the most frequent extraintestinal manifestations) eyes episcleritis iritis uveitis (acute anterior uveitis) liver and biliary system pericholangitis primary sclerosing [radiopaedia.org]

  The group of reactive skin manifestations of IBD includes aphthous stomatitis, erythema nodosum, pyoderma gangrenosum, and the rare Sweet’s syndrome. [web.archive.org]

  stomatitis, geographic tongue, and migratory stomatitis in higher prevalence than the general population. [en.wikipedia.org]

• Night Sweats

  sweats Loss of normal menstrual cycle Even if you think you are showing signs of Crohn’s disease symptoms, only proper testing performed by your doctor can render a diagnosis. [crohnscolitisfoundation.org]

  sweats weight loss IBD may also be associated with symptoms that do not appear to be related to the digestive system, such as: joint pain canker sores in the mouth inflammation of the eyes skin disorders irregular periods in females Children with IBD [medicalnewstoday.com]

• Arthritis

  Juvenile Rheumatoid Arthritis Juvenile rheumatoid arthritis (JRA) is a term used to describe a common type of arthritis in children. It is a long-term... [web.archive.org]

  IFX: infliximab, ETA: etanercept, RTA: rituximab, RA: rheumatoid arthritis, AS: ankylosing spondylitis, CD: Crohn’s disease, PsA: psoriatic arthritis. [hindawi.com]

  IBD-associated arthritis is used to describe types of inflammatory arthritis associated with IBD and include psoriatic arthritis, ankylosing spondylitis and reactive arthritis. [arthritis.org]

  Crohn’s disease associated with arthritis: a possible role for cross-reactivity between gut bacteria and cartilage in the pathogenesis of arthritis. Arthritis Rheum 1988; 31(8): 1077–9 PubMed CrossRef Google Scholar 26. [doi.org]

• Arthralgia

  The authors present the case of a 22-year-old female patient that was admitted to their hospital due to diarrhea, fever, arthralgias, and diffuse erythematous papules and plaques with vesicles and pustules affecting the patient's face, lips, arms, trunk [ncbi.nlm.nih.gov]

  Acetaminophen and NSAIDs/COX-2 inhibitors are usually the first line therapy for arthralgia. Recently, there are reports about probiotics being useful in IBD patients with arthralgia. [hindawi.com]

  Symptoms or findings presumed related to Crohn's disease Select each set corresponding to patient's symptoms: arthritis or arthralgia iritis or uveitis erythema nodosum, pyoderma gangrenosum, apththous stomatitis anal fissure, fistula or perirectal abscess [ibdjohn.com]

• Low Back Pain

  It is interesting that the high incidence of asymptomatic sacroiliitis (varying from 10% to 52%)[ 16, 17, 18 ] and on the other hand the equally high incidence (about 50%) of characteristic inflammatory low back pain in the absence of radiological findings [doi.org]

  These criteria have sensitivity and specificity of 82.9% and 84.4%, respectively, and have been validated for diagnosing axial SpA in patients with low back pain [38]. Management. [hindawi.com]

  It is interesting that the high incidence of asymptomatic sacroiliitis (varying from 10% to 52%) [16,17,18] and on the other hand the equally high incidence (about 50%) of characteristic inflammatory low back pain in the absence of radiological findings [web.archive.org]

  Steer S, Jones H, Hibbert J. et al Low back pain, sacroiliitis, and the relationship with HLA‐B27 in Crohn's disease. J Rheumatol 2003 30 518–522. [ PubMed ] [ Google Scholar ] 305. [ncbi.nlm.nih.gov]

• Myalgia

  Painful legs, known as "gastrocnemius myalgia syndrome", are rare complications that often precede abdominal manifestations. We herein report the case of a 38-year-old man who presented with bilateral leg myalgia lasting for 4 months. [ncbi.nlm.nih.gov]

  […] related to gut inflammation Type 1 peripheral arthritis Type 2 peripheral arthritis Pyoderma gangrenosum Aphthous ulcers Ankylosing spondylitis Primary sclerosing cholangitis Erythema nodosum Uveitis   Episcleritis Orbital myositis     Gastrocnemius myalgia [hindawi.com]

• Symmetrical Arthritis

  Type 2 (polyarticular) is a symmetrical arthritis involving 5 or more small joints that requires differentiation from juvenile rheumatoid arthritis. [tp.amegroups.com]

The standard laboratory tests do not show results specific for Crohn's disease. Anemia and hypoalbuminemia are common. C-reactive protein (CRP) levels and erythrocyte sedimentation rate (ESR) may be of use since there is an association with the presence of complications of Chron's disease [7]. Fecal calprotectin may serve as a marker for intestinal inflammation.

There are two serological tests of significant importance, one indicating the presence of anti-Saccharomyces cerevisiae antibodies (ASCA) which are mainly seen in Crohn's disease, the other showing positive results in patients with ulcerative colitis for perinuclear antineutrophil cytoplasmic antibodies (p-ANCA). These tests may help to distinguish these two diseases.

A number of imaging techniques are available for diagnosis. Whereas barium contrast imaging has been used for a long time, it is being replaced by ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and capsule endoscopy methods. These modalities have been extensively evaluated for accuracy in detecting various pathological aspects of Chron's disease [8], such as the extent of the disease at different locations within the GI tract, the severity of the lesions, the detection of intraabdominal fistulae and abscesses, and other features. Ultrasonography is a widely used and affordable technique that does not involve ionizing radiation, but its accuracy for diagnosing Crohn's disease depends on the location of the lesions, whereas the precision of MRI diagnosis is less depended on the position of the pathologic changes. All three methods (ultrasound, CT, and MRI) are highly accurate in identifying stenosis, fistulae, and abscesses. Barium studies can also detect fistulae. CT scans efficiently reveal extramural and hepatobiliary complications [9], as well as bowel wall thickening and edema. The advantage of MRI is the absence of radiation. Other imaging modalities include esophagogastroduodenoscopy (EGD), endoscopic retrograde cholangiopancreatography (ERCP), ileocolonoscopy, and balloon enteroscopy.

In Chron's disease lesions of the intestine often alternate with unaffected areas, which is the reason why they are called skip lesions. The histology may show the presence of non-caseating granulomas.

• Nephrolithiasis

  The prevalence of nephrolithiasis in IBD varies from 2% to 6% and is more frequent in CD than in UC[ 103 ]. Calcium-oxalate stones are the most common and are caused by hyperoxaluria due to increased intestinal absorption of oxalate. [doi.org]

  Heyman (3) classified the EIMs into several categories as well: colitis-related EIMs affecting the skin, eye, joint, mouth, and hepatobiliary system; impaired growth; EIMs secondary to complications of or as direct extensions of bowel disease including nephrolithiasis [tp.amegroups.com]

  The prevalence of nephrolithiasis in IBD varies from 2% to 6% and is more frequent in CD than in UC [103]. Calcium-oxalate stones are the most common and are caused by hyperoxaluria due to increased intestinal absorption of oxalate. [web.archive.org]

  […] from normal to those of an acute abdomen; assess for rectal sphincter tone, gross rectal mucosal abnormalities, presence of hematochezia Genitourinary: May include presence of skin tags, fistulae, ulcers, abscesses, and scarring in the perianal region; nephrolithiasis [emedicine.com]

• Colonic Stricture

  […] intestinal wall stop temporarily a hole or tear in the colon strictures or narrowing of the colon toxic megacolon, where swelling and trapped gas can lead to colon rupture, septicemia, and shock In order to diagnose IBD, a doctor will take a full medical [medicalnewstoday.com]

  Eur Journal of Clinical Microbiology, 6, 286-290. [ 42 ] Kaya, M., Aydin, F. and Buyukbayram, H. (2005) A rare cause of colonic stricture, amebiasis. [dx.doi.org]

  In Crohn’s disease, colonic strictures may be followed with annual surveillance and biopsy if the lesion can be traversed with a standard pediatric colonoscope. [doi.org]

• Microcytic Anemia

  Laboratory workup showed severe iron deficiency with microcytic anemia, hypoproteinemia, and hypalbuminemia. The patient’s blood pressure was low at 110/70 mmHg. [bmcgastroenterol.biomedcentral.com]

  Diagnosis Laboratory data for Crohn disease are nonspecific, as follows: The CBC may show hypochromic microcytic anemia, from iron deficiency due to GI blood loss, or normocytic anemia of chronic disease levels of acute-phase reactants (ESR and CRP) are [emedicine.medscape.com]

  Chronic intestinal bleeding with iron loss (due to bowel inflammation) causes a hypochromic and microcytic anemia with associated hypoferremia and hypoferritinemia; the chronic inflammatory disease (typically characterized by hyperferritinemia) can cause [doi.org]

  Features of microcytic anemia with low values of hemoglobin, hematocrit and mean corpuscular volume may, however, be seen in a child with a history of recurrent bleeding per rectum[ 35 ]. [ncbi.nlm.nih.gov]

• Normocytic Anemia

  Investigations Complete blood count was notable for a mild normocytic anemia (hemoglobin 119 g/L (reference range, 130–175 g/L) and mild eosinophilia of 0.82 g/L (reference range, 0–0.35 g/L)). [hindawi.com]

  Diagnosis Laboratory data for Crohn disease are nonspecific, as follows: The CBC may show hypochromic microcytic anemia, from iron deficiency due to GI blood loss, or normocytic anemia of chronic disease levels of acute-phase reactants (ESR and CRP) are [emedicine.medscape.com]

  Anemia of chronic disease results in a normocytic anemia. [en.wikipedia.org]

• Leukocytes Increased

  A dose increase of the G-CSF successfully normalized his leukocyte count. However, the stenosis worsened and surgical therapy was needed. [bmcgastroenterol.biomedcentral.com]

• Macrocytic Anemia

  Subjects were excluded if there was a known history of iron deficiency anemia (IDA), 14 UC, or macrocytic anemia. Furthermore, patients who used iron supplementation, B12 or folate within 3 months of study enrollment were also excluded. [doi.org]

• Colitis

  […] disease +4·0% [1·0-7·1] and APC for ulcerative colitis +4·8% [1·8-8·0]). [ncbi.nlm.nih.gov]

  The colitis is usually substantial, the clinical course of the colitis is quiescent, and rectal sparing is common. Moreover, PSC patients with UC have a higher risk of developing colorectal dysplasia/carcinoma than UC patients without PSC. [doi.org]

• Multiple Ulcerations

  Ulcerative colitis causes multiple ulcers to form on the intestinal wall. Most of the time, ulcerative colitis first affects the bottom part of the large intestine, near the rectum, and symptoms develop quickly. [nyulangone.org]

  The ulceration is shallow and the adjacent mucous membrane may appear nodular, lumpy or granular[ 30 ]. Twenty-five percent of SRUSs may appear as a polypoid lesion; 18% may appear as patchy mucosal erythema; and 30% as multiple lesions. [ncbi.nlm.nih.gov]

• HLA-B27

  or elevated CRP) or presence of HLA-B27 and any two other clinical features. [hindawi.com]

  Type 1 is usually associated with HLA-B27, HLA-B35, and HLA-DR103, while type 2 is associated with HLA-B44 (27). [tp.amegroups.com]

  However, they have only a transient benefit in HLA-B27 transgenic rats[ 24 ]. [doi.org]

  Histocompatibility human leukocyte antigen (HLA)–B27 is identified in most patients with ulcerative colitis, although this finding is not causally associated with the condition and the finding of HLA-B27 does not imply a substantially increased risk for [emedicine.medscape.com]

Mild Crohn's disease patients are usually initially prescribed 5-aminosalicylic acid preparations. If no improvement is noted, corticosteroids, 6-mercaptopurine/azathioprine or methotrexate are indicated, while biological agents are considered last resort before surgery. Moderate and severe cases benefit from the top-down approach, that uses a combination of biologic agents and steroids from the beginning. 6-mercaptopurine combined with a biologic agent efficiently induces remission [10].

5-aminosalicylic acid preparations include sulfasalazine and mesalazine. Mesalazine better prevents relapse than its peer. Corticosteroids effectively relieve severe systemic symptoms but are reserved for situations where obvious infection signs are absent. They should be administered for short periods of time and if withdrawal proves difficult, immunosuppressants should be considered. This therapy category is not without side effects, so patients need careful monitoring.

Biologic therapy includes agents such as infliximab, a chimeric mouse-human monoclonal antibody against tumor necrosis factor alpha (TNF-α), adalimumab and certolizumab pegol. The latter agents are less immunogenic, but seemingly equally effective. Natalizumab and vedolizumab are integrin antagonists, while ustekinumab inhibits interleukins 12 and 23. Other therapeutic agents that may prove beneficial include tacrolimus and mycophenolate mofetil. Surgical treatment is required for fistulae, abscesses, toxic megacolon, perforation, intractable hemorrhage, and strictures.

Crohn's disease has an overall favorable prognosis, but the course of the disease is marked by remissions and relapses. The risk of a fatal outcome is very small if the patient follows appropriate treatment. New therapeutic agents have improved survival even in individuals classically considered having increased risk, such as females with long disease duration [11]. The classical course of the disease included complications like chronic obstructive pulmonary disease and gastrointestinal malignancies, but their incidence has diminished in the current era. Relapses are more frequently encountered in the first year after diagnosis and may be as high as 50% of cases. Surgery is required in up to 39% of cases 10 years after diagnosis and sometimes more than on operation is needed [12]. The most common reason for surgery is stricture removal. The younger the patient is at the time of diagnosis, the higher the probability for multiple surgical interventions is. Crohn's disease of the proximal small bowel implies a higher risk of mortality than an ileal or ileocecal disease. The risk for colorectal cancer is also diminished by modern therapy. Life quality is near- normal in cases that are not very severe.

The etiology of Crohn's disease is at this time unknown, but several genetic, vascular, immunologic, microbial, environmental and psychosocial factors are thought to be involved. Oral contraceptive use and smoking also seem to play a role in disease etiology, as do nonsteroidal anti-inflammatory agents. These risk factors may cause Crohn's disease in individuals that are susceptible to develop an aberrant immunologic response [13]. Several abnormal genes thought to regulate mucosal immunity have been described. Despite this fact, Crohn's disease is not considered to be a genetic disease and Mendelian inheritance is absent. The first gene ever to be demonstrated to be involved in Crohn's disease susceptibility is CARD15, located on chromosome 16. It can be affected by over 60 mutations, but 3 are most frequent [14]. IL23R, PTPN22, CCR6, JAK2, IL12B, STAT3, CDKAL1 and LRRK2 gene mutations are other possibilities [15]. Most of these translate as immune function abnormalities, whereas the ATG16L1gene impairs the autophagosome pathway, with important implications in disease pathogenesis.

Inflammation caused by Listeria species, Pseudomonas species, and Mycobacterium paratuberculosis is considered dysfunctional in Crohn's disease cases [13]. This condition is believed to be also caused by increased production of TNF-α by macrophages [16]. Smoking increases the risk of Crohn's disease twice [17]. Fat rich diet is also involved in the etiology of this condition [18]. The disease is not caused by the measles vaccine, as once thought [19].

Therefore, there is no single etiology for Crohn's disease. This condition is caused by environmental factors that disrupt gut microbiota balance and abnormally stimulate the intestinal immune response in genetically susceptible individuals.

Crohn's disease is more frequent in urban areas than rural ones [20]. 43 children in 100.000 and 201 adults in 100.000 are estimated to suffer from this condition in America [21], whereas Europeans have a 5.6 per 100,000 inhabitants incidence [22]. Asian incidence of the disease ranges between 0.5 and 4.2%. Individuals belonging to the upper socioeconomic class are more frequently affected [23], as are individuals living in temperate climates and industrialized areas.

Disease incidence has two peaks, one between 15 and 30 years of age and one between the ages of 60 and 70 years. Most individuals are diagnosed before turning 30 years old. The female sex is slightly more prone to developing this condition, with a 1.1-1.8 times higher incidence than men [24]. However, during childhood, this ratio is reversed, with a male-to-female ratio of 1.6:1.

T lymphocytes play a key role in Crohn's disease pathogenesis. They respond in an unrestrained manner due to their defective regulation and secrete proinflammatory cytokines that recruit other inflammatory cells that, in turn, release more inflammatory substances, leading to unwanted process escalation and intestinal injury. These phenomena are more severe in cases with defective epithelial barrier integrity and abnormal autophagy [25]. The inflammatory infiltrate initially located around a crypt, after forming a crypt abscess progresses to mucosal ulceration and invasion of the deeper layers. The process ends with noncaseating granulomas formation, that extends to the entire intestine and possibly the adjacent structures, such as regional lymph nodes and the mesentery. The granuloma is the pathognomonic lesion of Crohn's disease [13]. The colon becomes atrophic and ulcerated, but lesions are interpolated with normal areas of mucosa.

The pathophysiology of bowel obstruction in Crohn's disease is explained by mucosal edema that narrows the intestinal lumen. Deep ulcers may transform into enterocutaneous, enteroenteral, enterovaginal or enterovesical fistulae. Frank intestinal perforation is rarer in Crohn's disease than other bowel inflammatory diseases because of the presence of multiple adhesions.

Crohn's disease cannot be prevented because its etiology remains unclear. Several nonspecific preventive measures have, however, been advanced. These include avoiding or stopping smoking, stress management, good hydration, optimizing vitamin D levels and having a well-balanced diet, rich in fibers, saturated fats, fruits, vegetables and omega-3 fatty acid. Processed food, preservatives, artificial flavors and colors, raw nuts and dairy consumption should be limited.

Crohn's disease is a chronic condition, part of the intestinal bowel diseases cluster, that extends throughout the entire gastrointestinal system, from the mouth to the anus. It is characterized by periods of relapse and remission. Patients complain about abdominal pain and diarrhea or about more severe symptoms that accompany intestinal obstruction and fistulization. The disease causes malnutrition, anorexia, nausea, vomiting, weight loss and fatigability. Acute periods are accompanied by fever and rectal bleeding. Children experience growth failure, that may precede gastrointestinal symptoms by a ling time. Bone loss and coping difficulties are not uncommon.

Clinical examination may reveal signs of anemia such as tachycardia and paleness. Jaundice is another possibility. The abdomen is more or less painful on palpation and evidence of hematochezia may be present. Skin lesions that may be encountered include ulcerations, pyoderma gangrenosum, and erythema nodosum. Puberty signs may be delayed and visual impairment may be due to episcleritis or uveitis. Arthritis associated with Crohn's disease predominantly affects large joints.

Diagnosis relies on laboratory and imaging tests. The first category includes anti-Saccharomyces cerevisiae antibodies and perinuclear antineutrophil cytoplasmic antibodies, in addition to fecal calprotectin and other standard tests. Computer tomography enterography or magnetic resonance enterography are slowly replacing more simple radiological tests and offer relevant information, such as the existence of strictures and fistulae. Superior digestive endoscopy and ileocolonoscopy must be performed in every case because they not only fully characterize mucosal aspect, but allow biopsy specimens to be obtained and investigated.

Treatment relies on several therapeutic classes: 5-aminosalicylic acid derivates, corticosteroids, immunosuppressive agents and monoclonal antibodies. Discomfort may be alleviated by antidiarrheal agents and anticholinergic and antibiotics are sometimes needed. Surgery is not curative in Crohn's disease, but it is often necessary in order to resolve disease complications like strictures, abscesses, and fistulae.

Crohn's disease causes inflammation throughout the entire digestive system, leading to abdominal pain, malnutrition, weight loss, mouth sores, fatigability, bloody stools, and diarrhea. The inflammatory process can be confined, however, to a single segment of the digestive tract. Symptoms install suddenly, but the patient may also have periods of remission, with no complaints. Affected individuals also complain about eyes and joints inflammation. In children growth and puberty are delayed.

The diagnosis is established using blood tests and imaging methods, but an upper intestinal endoscopy and colonoscopy are usually compulsory. These techniques allow direct visualization of the mucosa and pieces of the diseased tissue can be obtained and analyzed. With treatment, many achieve a good life quality. If complications such as fistulae, abscesses and bowel obstruction arise, surgery is needed.

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