38.2.1 Lower Endoscopy

Crohn’s Disease

Endoscopically, CD is often characterized by areas of inflammation separated by normal-appearing mucosa, which are called skip lesions. Any part of the GI tract from mouth to anus can be affected, although most commonly the ileum is involved (▶Fig. 38.1). Early mild lesions include small (< 5 mm) aphthous ulcers (▶Fig. 38.2). In more severe disease deep irregular and longitudinal ulcerations (▶Fig. 38.3, ▶Fig. 38.4) can be seen as well as a cobblestone appearance of the mucosa (▶Fig. 38.5). As the inflammation is transmural, it can result in strictures and fistulae. Often rectal sparing is seen. Biopsy specimens to confirm the diagnosis should be taken from the edges of ulcers and aphthous erosions (▶Table 38.1). Specific guidelines on how many biopsies should ideally be taken are lacking.

Table 38.1 Terminology of endoscopic lesions in Inflammatory Bowel Disease, from the ECCO guideline. ¹

Mucosal damage	Description	Grading
Loss of vascular pattern	Loss of normal mucosal appearance without well-demacated, arborizing capillaries	From patchy or blurred to complete loss
Erythema	Unnaturally reddened mucosa	From discrete or punctiform to diffuse erythema
Granularity	Mucosal pattern produced by a reticular network of radiolucent foci of 0.5–1 mm of diameter with a sharp light reflex	From fine to coarse or nodular, due to abnormal light reflection
Friability/bleeding	Bleeding or intramucosal hemorrhage before or after the passage of the endoscope	From contact bleeding (bleeding with light touch) to spontaneous bleeding
Erosion	A definite discontinuation of mucosa < 3 mm in size. Also described as pinpoint ulceration	Isolated, diffuse
Aphthous ulcer	White depressed center surrounded by a halo of erythema; (some consider this synonymous with “erosion”)	Isolated, multiple
Ulcer	Any lesion of the mucosa of unequivocal depth, with or without reddish halo	Isolated or multiple based on morphology: circular, linear, stellar, serpiginous, irregular shape Superficial or deep
Ulcer size (no underscore)	Defined in millimeter or classified as ≤ 5 mm; 5–20 mm; > 20 mm	Diffuse, mucosal abrasion with residual mucosa producing a polypoid appearance
Ulcer depth (no underscore)	Shallow (localized to submucosa)—no border Deep (beyond muscularis propria)—e.g., edges elevated > 1 mm
Stenosis	Narrowing of the lumen	Single, multiple, passable (by standard adult endoscope), unpassable, passable after dilation Ulcerated, nonulcerated
Postinflammatory polyps (previously “pseudopolyp”)	Polypoid lesion, usually small, glistering, isolated or multiple, scattered throughout the colon. Sometimes cylindrical or giant (> 2 cm) in size	Isolated, diffuse, occluding (“giant”)
Cobblestone	Mucosal pattern with raised nodules, resembling the paving of a “Roman” road	With or without ulceration

Ulcerative Colitis

Inflammation in UC tends to be continuous, confluent, and concentric. Characteristically, inflammation commences proximal to the anus. The demarcation between inflamed and normal areas is usually clear and in general there are no skip lesions. Initial lesions include loss of vasculature and hyperemia of the colonic mucosa (▶Fig. 38.6, ▶Fig. 38.7). In moderate disease, discrete ulcers surrounded by inflamed mucosa develop progressing to large, continuous ulcers with increasing severity of the disease (▶Fig. 38.8). “Backwash ileitis,” extension of macroscopic or histologic inflammation from the cecum into the most distal ileum, has been reported in up to 20% of patients with pancolitis ² , ³ and is associated with a more refractory course of disease. ⁴

38.2.2 Upper Endoscopy

38.2.3 Small Bowel Imaging

CD can affect segments of the small bowel out of reach of the colonoscope. Small bowel video capsule endoscopy should be considered in patients with suspected CD and negative ileocolonoscopy. ⁸ The Lewis score (LS) ⁹ has been developed to assess mucosal inflammatory disease in the small bowel. This scoring index is based on three capsule endoscopic variables: villous appearance, ulceration, and stenosis. In addition, each variable is assessed by other parameters including size and extent of the change. Using these parameters, a score range of 8 to 4,800 points was established: LS less than 135 reflects normal mucosal appearances, LS 135 to 790 mild mucosal inflammatory change, and an LS value greater than or equal to 790 moderate-to-severe mucosal inflammatory changes.

In patients with obstructive features or known stenosis, a cross-sectional imaging modality such as magnetic resonance enterography (MRE) or computed tomography enterography (CTE) should be the method of choice. ¹⁰ Furthermore, MRE can objectify the transmural nature of the disease, its anatomical distribution as well as the presence of extraluminal disease.

38.2.4 Endoscopic Ultrasonography

The cumulative incidence of perianal fistulas in CD range from 23 to 38%. ⁴ , ¹¹ Perianal fistula are often diagnosed and classified by using a combination of both clinical and imaging findings. Endoscopic ultrasound (EUS), magnetic resonance imaging (MRI), and examination under anesthesia (EUA) are accurate tests for determining fistula anatomy in patients with perianal CD. ¹² Combining two of the three modalities gives an accuracy of 100%. Examination under anesthesia in the hands of an experienced surgeon has been considered the gold standard in the assessment of perianal CD, with the advantage that surgical drainage of any abscesses and placement of noncutting setons can be performed as required. ¹³ Currently, it is advised to first perform a noninvasive procedure such as MRI to visualize perianal fistula unless there is a need for immediate drainage of sepsis. ¹⁴ For endoscopic ultrasonography endoanal probes are used transrectally. Fistulas are visible as hyperechoic tracks or beads within a larger hypoechoic tract consistent with surrounding inflammation. ¹⁵ Data from three small clinical trials suggest that fistula imaging by EUS can guide in medical decision making with better clinical outcomes. ¹⁶ , ¹⁷ , ¹⁸

38.2.5 Endoscopic Retrograde Cholangiopancreatography

Primary sclerosing cholangitis (PSC) is a chronic, cholestatic liver disease characterized by chronic inflammation and fibrosis of the biliary tract affecting both intrahepatic and extrahepatic bile ducts leading to the formation of bile duct strictures. The vast majority of patients with PSC have accompanying IBD. The presence of PSC increases the risk of colorectal cancer (CRC) development almost by a 10-fold, ¹⁹ furthermore PSC patients are at increased risk of developing cholangiocarcinoma with a 20% lifetime risk. ²⁰ Endoscopic retrograde cholangiopancreatography (ERCP) is the gold standard for diagnosing PSC. ERCP is used for diagnostic (brush cytology) and therapeutic purposes, that is, balloon dilation or stent placement.

38.3.1 Acute Colitis

In patients with chronic bloody diarrhea, endoscopy with mucosal biopsies is an important tool to evaluate the severity of disease ²¹ and to exclude other (infectious) causes of acute colitis, ²² such as cytomegalovirus (CMV) colitis, rectal mucosal prolapse, malignancy, and hemorrhoidal bleeding. ²³ In most cases unprepped sigmoidoscopy with minimal inflation is sufficient. Biopsies are particularly useful to exclude CMV colitis in patients with prolonged exposure to steroids and/or azathioprine. ²⁴ Furthermore, the endoscopic appearance predicts the course of the disease and may guide treatment intensification. For example, in UC it is known that the presence of extensive and deep ulcerations at endoscopy is associated with an increased risk of colectomy. ²⁵ , ²⁶

38.3.2 Routine Endoscopy

Routine endoscopy in IBD patients in clinical remission, besides surveillance for dysplasia and after surgery, has been considered to be unnecessary. In these cases, noninvasive tests and surrogate markers of disease activity, ²⁷ such as fecal levels of calprotectin ²⁸ or lactoferrin, ²⁹ , ³⁰ can be used to assess disease activity. Whether treatment intensification to attain “mucosal healing” despite the absence of symptoms is to be recommended remains to be studied. In the cases of a suspected relapse, refractory disease, new/unexplained symptoms, change of medical therapy, or when surgery is considered, endoscopy should be seriously performed.