Fig. 12.1
Enterocolic fistula (arrows) in Crohn’s disease
Fig. 12.2
Enterocutaneous fistula in Crohn’s disease. (a) CT findings, (b) a skin photo
Fig. 12.3
Enterovesical fistula in Crohn’s disease (arrow)
Fig. 12.4
Rectovaginal fistula
Type | Incidence (%) |
|---|---|
External(skin)/perianal | 66 |
Internal | 34 |
Ileosigmoid | 25 |
Other ileocolic | 23 |
Ileovesical | 20 |
Ileum/rectum to female genital tract | 12 |
Ileoileal | 11 |
Coloenteric | 9 |
Fig. 12.5
Vulva edema due to rectovaginal fistula in Crohn’s disease
Crohn’s perianal fistulae may arise from inflamed or infected anal glands or penetration of fissures or ulcers. Examination under anesthesia (EUA) has an important role in the diagnosis and classification of perianal fistula. It allows immediate abscess drainage (Fig. 12.6) and/or seton placement. Pelvic magnetic resonance imaging (MRI) is a highly accurate noninvasive modality for the diagnosis and classification of perianal fistulae and is regarded as the gold standard (Fig. 12.7) [3]. To ensure diagnostic accuracy and optimal management, a combination of endoscopy and MRI/endoscopic ultrasound and EUA is required. Endoscopic assessment for proctitis is essential to determine the most appropriate management strategy.
Fig. 12.6
Fistulotomy with drainage. Draining abscess and performing fistulotomy can relieve perianal fistula with abscess
Fig. 12.7
MRI findings of perianal fistula (arrows)
Once fistula formation is developed, it rarely heals spontaneously or even despite medical therapy, and frequently requires surgical therapy. However, a meta-analysis showed the improvement of fistulae with immunomodulatory therapy such as azathioprine [4]. Antibiotics and thiopurines may contribute to symptom improvement but are limited by their slow onset of action, low remission rates, and high recurrence rates. Infliximab and adalimumab are effective for induction and maintenance of fistula closure (36–58 %). Moreover, antitumor necrosis factor α (TNF-α) and thiopurine combination therapy may lead to a higher fistula closure rate compared to monotherapy. However, a diverting temporary stoma remains an option for patients with severe, complicated therapy-refractory fistulizing disease [5].
12.3 Nonfistulizing Perianal Lesions
While various types of perianal lesions can occur in patients with CD (Table 12.2), one of the important perianal complications is anal ulceration (Fig. 12.8). Classically, anal ulcer of CD is considered as painless lesion; however, pain had been reported up to 70 % in a referral center-based study [6]. Other symptoms such as discharge, pruritus, and bleeding also can be developed. Anal ulcer in CD usually shows irregular, undermined, and detached shape with edematous border [7]. Multiple lesions can be observed, but the extension to the outside of anal canal is rare. Little is known about the long-term outcomes of anal ulceration in patients with CD; however, most of them heal spontaneously during treatment. Rarely, when the ulcer develops cavitation, it can lead to formation of abscess, stricture, or fistula with poor prognosis.
Table 12.2
Types of perianal lesions in 202 consecutive patients in a Crohn’s disease follow-up clinic [8]
Type of lesion | Number of patients (%) |
|---|---|
Skin tag | 75 (37) |
Fissure | 38 (19) |
Low fistula | 40 (20) |
High fistula | 12 (6) |
Rectovaginal fistula | 6 (3) |
Perianal abscess | 32 (16) |
Ischiorectal abscess | 8 (4) |
Intersphincteric abscess | 7 (3) |
Supralevator abscess | 6 (3) |
Anorectal stricture | 19 (9) |
Hemorrhoids | 15 (7) |
Anal ulcer | 12 (6) |
Total patients with perianal lesions | 110 (54) |
Fig. 12.8
Anal ulcers
Another major anal complication is anal skin tag (Fig. 12.9). Pathogenesis of anal skin tag is explained by lymphedema secondary to lymphatic obstruction [9]. The AGA Institute classified skin tags as two types. One is large, edematous, hard, cyanotic skin tags which typically arise from a healed anal fissure or ulcer. And the other is “elephant ear” tags that are flat and broad or narrow, soft painless skin tags [10]. A report revealed that anal skin tags were found more frequently in patients with CD (75.4 %) as compared to patients with UC (24.6 %); therefore, confirming anal skin tags can aid to distinguish CD from indeterminate colitis [11]. Skin tags are usually benign; however, they can be enlarged in case with inflammatory flare-up of underlying disease. Surgical removal of anal skin tag is generally not recommended, but “elephant ear” skin tag can be treated by local excision.
