Crohn's disease is an ongoing inflammatory disease of the bowel that most often causes abdominal pain and diarrhea Figure 01. Crohn's disease involves periodic pain, swelling and redness (inflammation) and loss of tissue (ulceration) of the gastrointestinal tract. Most people have involvement of the lower part of the small intestine (ileum), but any part of the digestive system can be affected, from the mouth down to the anus. Symptoms are most commonly abdominal pain and bloody diarrhea, but vary depending on the location of the inflammation.
Figure 01. Digestive System Anatomy
The disease usually starts in childhood or early adulthood, and is characterized by unpredictable flare-ups and remissions. During remissions, which may last for years, the person may feel well and be free of symptoms. Crohn's disease shares many features with ulcerative colitis, an inflammatory bowel disease that involves only the colon. Unlike ulcerative colitis, which affects only the most surface layers of the intestine (the mucosa) and spreads through the colon in a continuous fashion, Crohn's disease typically penetrates all layers of the intestine and can have a patchy distribution throughout the entire gastrointestinal tract. About 15% of patients with inflammatory bowel disease have characteristics of both conditions, and cannot be clearly diagnosed as having one or the other.
If Crohn's disease increases in severity, complications such as intestinal blockage can develop. Inflammation tends to thicken the bowel wall with swelling and fibrous scar tissue. This narrows the opening of the intestinal tube, and may eventually cause a blockage, the most common complication of Crohn's disease.
Another complication is the formation of a fistula, an abnormal passageway between two organs that do not normally connect with one another. Fistulas are formed when ulcer tracts burrow through the bowel wall and into adjacent organs, such as the bladder, the vagina, another area of bowel, or out through the skin. The introduction of intestinal contents into normally sterile areas of the body can lead to pockets of infection (abscesses). The areas around the anus and rectum are often involved in fistula formation.
Crohn's disease can be a serious disease requiring hospitalization and multiple surgeries. Crohn's disease usually starts in late childhood or early adulthood, and can seriously disrupt a person's education, career goals, and social life. Although it is not considered to be a fatal disease, it can cause anemia, malnutrition, and weakness during severe or prolonged attacks, and may require hospitalization and multiple surgeries to correct complications. Fortunately, effective medicines and surgery can help most people keep the disease in check most of the time.
Some patients with Crohn's disease also have inflammation in other parts of their body. Inflammation may also develop in the joints, skin, or eyes. Kidney stones, gallstones, and other diseases of the liver and bile system (including the liver, the gallbladder and the tract that carries bile), also tend to occur more often.
The reason some people develop Crohn's disease is unknown, though it may result from an abnormal immune response, perhaps to a virus or bacteria. Crohn's disease has been blamed on genetic factors, bacteria, viruses, stress, and dietary components, but no theory offers a clear-cut explanation. It tends to run in families, and is more common in certain ethnic groups, indicating that a genetic component and/or an infectious agent is likely.
For whatever reason, the body mounts an inflammatory response in the digestive tract (or “intestinal tract”) as if a foreign invader such as a virus, an allergen, or bacteria, were present. It's possible that the abnormal response may continue even after the provoking agent is no longer present.
People with Crohn's disease may be considerably emotionally distressed, leading some to suspect that psychological factors are the primary cause of the condition. There is no evidence, however, to support this. Instead, most experts believe that emotional disruption is an understandable and common response to a problem like Crohn's disease, a chronic condition that frequently recurs beyond one's control.
An individual's symptoms depend on where in the digestive tract the disease is flaring, and how severe it is Table 01.
Most people have involvement of the ileum, the lower part of the small intestine, causing abdominal pain and diarrhea. Abdominal pain is common after eating, especially in the lower right area.
Diarrhea is often present, and tends to be urgent if the rectum is involved. Observable blood in the stool may occur intermittently, and can be serious and persistent enough to lead to anemia. Some people also experience low-grade fever, nausea, and vomiting. If the anus is involved, fissures or cracks may be evident, and fistulas and abscesses may form.
Some people also have inflammation in places other than their intestines, and may develop skin or mouth lesions, pains in the joints, and eye irritation.
With severe disease, weight loss and extreme fatigue due to nutrient and blood loss may develop, and may require hospitalization to stabilize the individual. High fever, vomiting, severe pain, and weakness can indicate an emergency, and may require immediate evaluation of an infection or an intestinal blockage or perforation.
In children, delayed development and poor growth may be evident before any other symptoms are apparent.
Table 1. Symptoms of Crohn's Disease
Common but periodic symptoms Cramping pain Diarrhea, possibly with visible blood Fever Nausea Weight loss Fatigue Severe symptoms Sores and bleeding around anus Sores and bleeding in mouth Skin lesions Joint pains Itchy or irritated eyes Children weight loss or slowing of growth rate Symptoms requiring immediate medical evaluation Fever Severe pain Vomiting Weakness
Crohn's disease usually starts in childhood or early adulthood. It tends to run in families and has a high incidence in Jews. Most cases of Crohn's disease start before age 30, and a second smaller peak of incidence occurs when people are in their fifties and sixties. About 20% of people diagnosed have a relative who also has inflammatory bowel disease, most often a brother or sister.
Jewish people of European descent have a fourfold higher incidence than the general population.
Smoking is associated with an increased risk, especially of disease recurrence following surgery.
A clear diagnosis is sometimes difficult to obtain because symptoms overlap with symptoms of several other conditions. Diagnosis may involve numerous tests and time. The most common symptoms, intermittent diarrhea and pain, could also be caused by ulcerative colitis, irritable bowel syndrome, cancer, diverticular disease, or infectious agents. Bloody diarrhea can be caused by ulcerative colitis, diverticulosis or infection.
A complete history and physical are essential, including blood tests and stool samples.
An upper gastrointestinal series—x-rays taken after the patient drinks a substance called barium—is an important diagnostic procedure that may be used to identify the nature and extent of the disease. Barium is a chalky substance that appears white on x-rays . When barium is ingested, the stomach and small intestines can be seen on the x-ray. When barium is inserted into the rectum, the colon and the lowest part of the ileum can be seen. Barium x-rays may reveal typical features of Crohn's disease, including involvement of the lower part of the ileum, with narrowing, the formation of nodules, and deeply slit ulcers that give a cobblestoned appearance. A CT scan— a type of x-ray that allows doctors to see internal organs—may reveal bowel wall thickening and small abscesses. It is painless and only requires that the patient lay as still as possible for up to an hour.
Another important diagnostic procedure that may be done is a colonoscopy. This procedure allows the viewing of the interior lining of the large intestine (colon) using a colonoscope, a flexible fiber-optic tube. An eyepiece lets the doctor to see inside the body. Colonoscopy allows the doctor to examine and take biopsies of suspicious areas of the colon. This procedure is best performed when a patient's symptoms are in remission.
When a patient is critically ill with severe pain and weakness, an intestinal blockage or perforation (which may or may not be due to Crohn's disease) as well as appendicitis or diverticulitis must be considered and quickly diagnosed. A colonoscopy may be too risky to perform at such a time. An abdominal CT or ultrasound may be needed to determine if any of these conditions are present.
The diagnosis and treatment of Crohn's disease usually involves a team of health care providers, including the patient's primary-care doctor, a doctor who specializes in diseases of the digestive tract (gastroenterologist), and a surgeon if necessary. A dietitian and counselor can also be helpful.
Prevention and Screening
- Common Side Effects of AntidepressantsFind out about common and not-so-common side effects of antidepressants and how to manage them.
- How Drugs Can Lower CholesterolDiscover how cholesterol-lowering medications work in your body to bring your cholesterol numbers down to ideal levels.
- Do Over-the-Counter Proton-Pump Inhibitors Work?You might wonder why you need a prescription for GERD if many PPIs are available over the counter. Get the answers to this and other questions about OTC PPIs.