Symptoms of inflammatory bowel disease (IBD) can begin years before the condition is officially diagnosed through clinical testing.

Recent research published in PLOS Medicine reveals that IBD may have a long “symptomatic period” before it can be identified by standard procedures like endoscopy or biopsy. In some cases, symptoms may appear more than 10 years before clinical confirmation.

The study also found that individuals who exhibit symptoms such as abdominal pain, diarrhea, or rectal bleeding—but have a normal endoscopy—still face a higher risk of developing IBD within the next 30 years.

According to lead study author Dr. Jiangwei Sun, a postdoctoral researcher at the Karolinska Institutet in Sweden, healthcare providers should remain vigilant. Patients who have GI symptoms requiring endoscopy may still be at risk for future IBD even if the initial results are normal.

IBD refers to a group of conditions, including Crohn’s disease and ulcerative colitis, that cause chronic inflammation in the digestive tract. The disease affects around three million people in the U.S., most of whom are diagnosed before the age of 35. Despite its impact, early signs of IBD are often difficult to distinguish from other gastrointestinal issues, making early diagnosis a challenge.

Common Symptoms of IBD

The two primary forms of IBD—Crohn’s disease and ulcerative colitis—affect different areas of the digestive system. Crohn’s disease may impact any part of the gastrointestinal tract, from the mouth to the anus, while ulcerative colitis is usually confined to the colon and rectum.

Despite this, both types share similar symptoms, which may include:

  • Chronic or recurring diarrhea

  • Abdominal pain and cramping

  • Rectal bleeding or blood in the stool

  • Fatigue

  • Unexplained weight loss

Normal Biopsies Don’t Always Eliminate Future IBD Risk

In the study, researchers analyzed gastrointestinal biopsy records from Sweden’s national health database, dating from 1965 to 2016. They focused specifically on patients who had a GI biopsy showing normal mucosa—meaning no disease was clinically visible at the time.

The study involved nearly 460,000 individuals who had undergone a lower or upper GI biopsy with normal results. These individuals were compared with their siblings and others from the general population who had not received a GI biopsy.

The follow-up period ranged from 10 to 30 years. Over time, 2.4% of those with a normal lower GI biopsy developed IBD, compared to 0.4% in the general population. The trend was similar for those who had a normal upper GI biopsy—indicating a continued risk for Crohn’s disease or ulcerative colitis.

Dr. Jeffrey Berinstein, a gastroenterologist at Michigan Medicine, who was not part of the study, noted that although the relative risk increased, the overall number of cases remained relatively small. He emphasized that this finding should not discourage people from undergoing necessary biopsies.

To put it in perspective, the study found that for every 37 people who had a normal biopsy, one person went on to develop IBD within 30 years.

IBD Is Often Difficult to Detect Early

One of the main challenges with IBD is that its symptoms—abdominal pain, diarrhea, rectal bleeding—can also appear in other conditions such as irritable bowel syndrome (IBS) or hemorrhoids. As a result, the disease often isn’t diagnosed until symptoms become more severe or obvious, such as significant blood in the stool, unexplained weight loss, or anemia.

Doctors often describe IBD as an "insidious" disease, because symptoms can progress slowly. Many patients adapt to the discomfort, which delays diagnosis until considerable bowel damage has occurred.

According to Dr. Stefan Holubar, a colorectal surgeon at Cleveland Clinic, individuals at high risk of IBD with even mild symptoms should establish care with an IBD specialist early. This helps providers monitor patients over time and potentially catch the disease earlier, preventing long-term intestinal damage.

The Importance of Ongoing Monitoring

While not every patient will need repeat endoscopies after a normal result, doctors should be prepared to reassess patients if symptoms persist or worsen despite standard, non-IBD treatments.

Dr. Berinstein explained that even if a biopsy appears normal, symptoms that don’t improve warrant a second look. The absence of clear signs during the initial examination should not rule out future concern.

Although IBD is a lifelong condition, it is generally manageable with the right treatment plan. Advances in medical research have significantly improved the outlook for patients, with more targeted and effective therapies becoming available each year.

Dr. Holubar described this as a “Golden Age” for IBD care, where a variety of medications now exist to control inflammation and support patients in leading a more normal and active life.

A Quick Review

IBD symptoms can appear long before they are detectable by medical tests like biopsies or endoscopy. People with early GI symptoms—especially those experiencing abdominal pain, diarrhea, or rectal bleeding—should be monitored over time, even if their initial tests are normal.

Healthcare providers should be aware that a normal GI biopsy does not completely eliminate the possibility of developing IBD in the future. Early identification and regular follow-up are essential in preventing long-term damage and ensuring the best possible outcomes for patients.

With proper monitoring and the growing number of treatment options available today, IBD is a condition that many people can manage effectively—leading to a better quality of life and fewer complications over time.