Clinical History
Young male patient affected by Crohn’s disease without previous surgical procedures and currently not undergoing medical treatment, complained of inability to pass stools and gas for 3 days. Diffuse abdominal tenderness without peritonism, empty rectum at digital exploration. Raised inflammatory laboratory markers (16600 WBC/mmc, 18 U/L C-Reactive Protein).
Imaging Findings
Plain abdominal radiographs obtained in Emergency Department disclosed markedly dilated jejunal loops with prominent air-fluid levels, absent colonic gas. Urgent contrast-enhanced multidetector CT with multiplanar reformations was requested to confirm mechanical obstruction, grade its severity and visualise site and cause to allow prompt treatment choice.
The majority of the small bowel loops appeared dilated with gas-fluid levels at different heights, a 5 cm maximum ileal diameter and abundant endoluminal fluid providing intrinsic negative contrast, findings consistent with high-grade mechanical obstruction. A long segment of the distal ileum showed stratified mural thickening with enhancing mucosa and oedematous submucosa, consistent with active Crohn’s disease, associated mesenterial fibrofatty proliferation and comb sign. Mural stratification with the fat halo sign, consistent with chronic inflammatory disease was seen in the collapsed right colon and ileocaecal valve.
Following unsuccessful medical treatment, surgery with ileocaecal resection was performed to relieve obstruction.
Discussion
Characterised by chronic transmural inflammation of the gastrointestinal tract, Crohn’s disease (CD) usually occurs in the distal ileum and proximal colon. Acute CD-related surgical emergencies include intestinal obstruction, perforation, intra-abdominal fistulas and abscesses. Although medical therapeutic options including anti-TNF medications currently allow optimal disease control, incidence of surgery during disease course has not significantly changed, with obstruction representing the most common indication (in emergency in over 30% of cases) [1, 2].
Occurring in nearly 50% of CD patients, variable-degree small bowel obstruction (SBO) may result from to acute transmural inflammation, from cicatricial stenosis in long-standing disease, from postoperative adhesions or hernias in patients with previous surgical interventions. Sometimes an unknown inflammatory bowel disease initially presents as acute obstruction [3, 4].
Initially, SBO in CD should be managed conservatively since acute inflammatory exacerbations are potentially managed with medical therapy. Conversely, complete obstruction, non-responsive and fibrotic strictures require surgical intervention [3, 6].
Although with limited specificity, plain abdominal radiographs are useful to confirm clinical suspicion of acute obstruction showing distended small bowel loops with multiple air-fluid levels in upright or lateral decubitus views, wider than 2.5 cm and differing more than 2 cm in height in severe cases [5].
Currently, contrast-enhanced multidetector CT with multiplanar reformations is largely requested as the modality of choice to investigate bowel obstruction, with retained intraluminal fluid providing intrinsic negative contrast. MDCT allows to assess mural, endoluminal and extramural abnormalities, confirms presence of obstruction, grades its severity, identifies its site as the transition point between dilated and collapsed loops, usually clarifies most probable underlying cause and detects possible complications such as strangulation [4, 5].
Mechanical SBO is diagnosed when dilated (more than 2.5 cm between outer walls) enteric loops are observed proximally to a transition zone, with collapsed distal bowel. Abundant endoluminal fluid and multiple air-fluid levels are usually present; although uncommon, fecal retention in the small bowel is a specific finding [4, 5].
As demonstrated with this case, circumferential mural thickening of the involved bowel segment with stratification pattern is the hallmark of active CD; ileocecal valve involvement, fibro-fatty mesenterial proliferation and prominent perienteric vasculature (comb sign) are suggestive associated findings. Conversely, transmural fibrosis in longstanding disease leads to loss of mural stratification with homogeneous attenuation of the thickened bowel [3, 5].
MDCT reliably allows correct therapeutic choice, differentiating acute exacerbation from fibrosis and adhesions. Furthermore, clinically unknown CD should be suspected in patients with SBO [3].
Differential Diagnosis List
High-grade small bowel obstruction due to Crohn's disease
Obstruction from adhesions
Obstruction from hernia
Fibrotic stenosis
Carcinoma
Intestinal lymphoma
Bowel ischaemia – infarction
Vasculitis
Final Diagnosis
High-grade small bowel obstruction due to Crohn's disease
