63revealed an accuracy of 93.7% in detecting POR confirmed by radiography and
endoscopy and biopsy, 82% sensitive and 100% specificity when using a bowel wall
thickness >5 mm as a positive detection [ 16 ]. This study was limited by small num-
ber of POR occurrences (n = 9). These findings were corroborated by Andreoli et al.
in 41 postoperative CD patients with TUS and concurrent ileocolonoscopy using the
same bowel wall thickness cutoff with 81% sensitivity, 86% specificity, 83% accu-
racy, 96% PPV, and 57% [ 17 ].
The addition of contrast improves the capability of US in a technique termed small
intestine contrast ultrasonography (SICUS). Using SICUS and an oral contrast solu-
tion with a decreased bowel wall thickness cutoff of 3 mm for at least 4 cm at the
perianastomotic area, bowel dilation (>25 mm), or stricture (<10 mm), Calabrese
et al. analyzed 72 postoperative CD undergoing ileocolonoscopy and SICUS within 6
months and found an increased sensitivity of 93% [ 18 ]. Bowel wall thickness also
strongly correlated with Rutgeerts score (p = 0.0001, r = 0.67). These findings were
supported when using intravenous contrast-enhanced US as well. Paredes et al. using
cutoffs of >5 mm bowel wall thickness or >46% contrast enhancement determined a
98% sensitivity, 100% sensitivity, 100% PPV, and 92% NPV for detecting endoscopic
recurrence (i1–i4) [ 19 ]. While suggesting the utility of abdominal ultrasound in
detecting POR, the clinical usefulness of these techniques in the United States remains
limited due to the requirement of experienced radiologist with advanced training.
Predictors of Postoperative Recurrence
Patient Factors
Many studies have evaluated factors influencing the development of POR. These are
outlined in Table 5.3. These factors can be divided into patient-oriented, disease-
related, and surgery-specific characteristics. The strongest and most consistent
patient-specific factor is cigarette smoking after surgery. Sutherland et al. demon-
strated both 5- and 10-year recurrence rates were significantly increased in smokers
(36% and 70%, respectively) than in nonsmokers (20% and 41%, respectively) with
an odds ratio (OR) of 2.1 (p = 0.007) [ 20 ]. Women smokers were also found to be
at higher risk than men who smoked (OR 4.2; 95% CI 2.0–4.2 women; OR 1.5; 95%
CI 0.8–6.0 men). The risk of recurrence with smoking is also dose dependent with
patients smoking ≥15 cigarettes daily having higher rates or POR and other studies
reporting a clear dose response [ 21 , 22 ]. Patients who quit smoking postoperatively
have a POR risk similar to nonsmokers. In a questionnaire study of 267 CD patients
following ileocecal resection, Ryan et al. found that patients who quit smoking fol-
lowing surgical resection had significantly lower relative incidence rates (RIR) for
one, two, and three reoperations for POR at any site (RIR 0.25, 95% CI 0.15–0.41;
RIR 0.30, 95% CI 0.16–0.57; and RIR 0.25, 95% CI 0.10–0.71, respectively) as
well as recurrent ileocecal CD (RIR 0.27, 95% CI 0.15–0.47) [ 23 ]. Thus postopera-
tive smoking represents a significant modifiable risk factor for POR.
5 Use of Biologics in the Postoperative Management of Crohn’s Disease