Jejunum
Ileum
Terminal ileum
Cecum
Appendix
Right colon
Transverse colon
Left colon
Sigmoid colon
Rectum
Anus
IBDology — enabling an evidence-accelerator based approach to all aspects of IBD Surgical care.
Average lag from research to routine clinical care: ~17 years. — Institute of Medicine, Crossing the Quality Chasm (2001).
IBDology aims to shorten the time from publication to practice using “deep & narrow,” queryable large language models (AI) — to put the newest evidence into the hands of providers and patients faster.
Frequently Asked Questions
Quick, plain-language answers to the questions we hear most.
What is IBD?
IBD (inflammatory bowel disease) is chronic, immune-driven inflammation of the gut. It comes in two main forms — ulcerative colitis (UC) and Crohn's disease — with a middle ground, IBD-unclassified, when the two can't be told apart. Medicines control most disease; surgery enters when medicines fail or complications develop.1,2
What are the three forms of IBD — UC, Crohn's, and IBD-unclassified?
Ulcerative colitis (UC) is continuous inflammation limited to the colon and rectum; because the disease lives in the colon, removing it — often building a J-pouch — can be curative.1 Crohn's disease (CD) is patchy, full-thickness inflammation that can occur anywhere from mouth to anus; surgery treats complications (strictures, fistulas, abscesses) but is not curative, so operations aim to spare bowel.2 IBD-unclassified (IBD-U) is colitis that isn't clearly UC or Crohn's — the uncertainty matters most when deciding whether a J-pouch is safe.3
What do the key terms mean — IPAA, colectomy, IBD-PSC, perianal Crohn's?
IPAA / “J-pouch” (ileal pouch–anal anastomosis) is the restorative operation for UC: after the colon and rectum come out, the small intestine is folded into an internal pouch joined to the anus, so stool still passes normally — no permanent bag.1 Colectomy and proctocolectomy mean removing the colon, or the colon and rectum together — the step before a J-pouch or a permanent ileostomy. IBD-PSC is IBD together with primary sclerosing cholangitis, a scarring bile-duct disease that raises colorectal-cancer risk and changes surveillance.4,5 Perianal Crohn's is Crohn's around the anus — fistulas, abscesses, and draining setons — managed very differently from disease inside the bowel.2
Where does surgery fit in IBD?
Most patients are managed medically — biologics and other drugs.14 Surgery is considered when medicines can't control the disease, when a complication develops (obstruction, abscess, fistula, bleeding), or when precancerous change is found on surveillance. In UC, surgery can be curative; in Crohn's, it manages complications while preserving bowel.1,2,6
What is IBDology?
IBDology is the front door to a family of inflammatory bowel disease (IBD) resources from the Holubar Lab. It points you to the right site for your need — whether you are a clinician looking for evidence and quality data, or a patient looking for plain-language education.
Which sites are for patients and which are for providers?
Patient sites include Pouchy (J-pouch), Crohnz (Crohn's), and pCrohns (perianal Crohn's). Provider/clinician sites include Pouchology (pouch literature) and Crohnsology (Crohn's evidence). The consortia — iPouch, iCrohnz, and NSQIP IBD — serve clinicians and researchers.
I have a J-pouch (IPAA). Where should I start?
Patients and families should start at pouchy.org for friendly, plain-language education. Clinicians and researchers can search the pouch literature at pouchology.org.
I have Crohn's disease. Which site is for me?
For intestinal Crohn's, patients should visit crohnz.org; if you have perianal disease (fistulas, abscesses, setons), see pcrohns.org. Clinicians can use crohnsology.org for the evidence base.
I've been told I have IBD-unclassified (IBD-U). What does that mean?
IBD-unclassified (also called indeterminate colitis) is inflammatory bowel disease of the colon that doesn't clearly fit ulcerative colitis or Crohn's. Many patients later declare as one or the other, and a substantial share behave like UC. The distinction matters most for surgery — especially whether a J-pouch (IPAA) is advisable. We built a dedicated resource for exactly this grey zone: ibdunclassified.org.3
What is IBD-PSC?
IBD-PSC is inflammatory bowel disease together with primary sclerosing cholangitis, a liver condition. The overlap changes surveillance, colorectal cancer risk, transplant considerations, and pouch decisions.4,5,10 Learn more at ibdpsc.org.
Who runs these sites?
They are produced by the Holubar Lab, led by Stefan D. Holubar, MD, MS, Professor of Surgery in the Department of Colon & Rectal Surgery at Cleveland Clinic. The sites are educational and do not replace advice from your own care team.
About IBDology
IBDology is the hub for a family of inflammatory bowel disease resources from the Holubar Lab, led by Stefan D. Holubar, MD, MS, Professor of Surgery, Department of Colon & Rectal Surgery, Cleveland Clinic, Cleveland, Ohio. Each site translates the best available evidence into resources for either clinicians or patients — from the iPouch and NSQIP IBD quality consortia to plain-language guides for living with a J‑pouch or Crohn's disease. These resources are designed and built in‑house, pairing clinical expertise with custom informatics and AI.
Some content may be AI-assisted and reviewed by the lab. These sites are educational and are not a substitute for professional medical advice.
This hub was created by Stefan D. Holubar, MD, MS, FACS, FASCRS, Professor of Surgery at Cleveland Clinic and the Cleveland Clinic Lerner College of Medicine & Case Western Reserve University. A fellowship-trained colorectal surgeon who specializes in inflammatory bowel disease—and, living with IBD and a J-pouch himself, a patient too—he brings both perspectives to this work. He is also a clinician-informatician who designs and builds the AI and decision-support tools behind these sites—from clinical risk calculators and an AI interface to the pouch literature to this hub itself. He is co-PI of the Crohn's & Colitis Foundation IBD-SIRCQ and the ACS-NSQIP IBD Collaborative, founder of the iPouch Consortium, and has authored over 300 peer-reviewed publications.
Dr. Holubar is an employee of Cleveland Clinic, and has the following disclosures: research funding from the American Society of Colon & Rectal Surgeons and the Crohn's & Colitis Foundation, and has no other disclosures or conflicts of interest.
Support & community
Trusted, independent organizations and communities for people living with inflammatory bowel disease, an ostomy, or a J‑pouch — and for their families.
External resources are independent of the Holubar Lab; listing does not imply endorsement. Always verify with your own care team.
The 100 most-cited IBD papers of all time
The most-cited inflammatory bowel disease papers ever published, ranked by total citations. These are the landmark studies — epidemiology, genetics, the microbiome, and the trials that defined modern IBD care.
Method: Pool ranked by OpenAlex cited_by_count (all citing sources). Candidate pool: Top 700 most-cited works under the OpenAlex IBD, ulcerative-colitis, and Crohn's-disease concepts (relevance score >= 0.3), with a PubMed ID and year. Citation counts: OpenAlex (all citing sources). Generated: 2026-06-29. Counts are dynamic and rise over time.
The 100 most-disruptive IBD papers of all time
Disruptiveness is not the same as popularity. The CD5 disruption index (Funk & Owen-Smith 2017; Wu, Wang & Evans 2019) measures whether a paper eclipsed the work before it — later papers cite it instead of its predecessors (+1, disruptive) versus alongside them (−1, consolidating). These IBD papers reshaped their field the most.
Method: CD_5 (5-year forward window) over the PubMed-indexed pool via the NIH iCite citation graph (Funk & Owen-Smith 2017; Wu, Wang & Evans 2019). Eligible: published <= 2021 (full window), >= 3 references, >= 100 citations. Formula: CD5 = (ni − nj) / (ni + nj + nk), in [−1, +1]. Citation graph: NIH iCite. Generated: 2026-06-29.