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fecal calprotectin can be a useful, noninvasive screening tool for detecting of POR. In
an analysis of a randomized controlled control of postoperative CD patients under-
going colonoscopy at 6 and 18 months with fCal measurements, Wright et al. found
similar predictive capability of fCal and suggested a potential avoidance of colonos-
copy in 47% postoperative patients using the testing characteristics of fCal [ 15 ].
Furthermore, Wright et al. also investigated fCal levels as a marker of response
to treatment. In their study, patients randomized to receive step-up postoperative
medical therapy or not (see POCER trial discussion under “Postoperative
Prophylaxis” section). The authors found fCal concentrations significantly decrease
in response to intensification of drug therapy in patients with evidence of endo-
scopic recurrence (from 324 to 180 μg/g at 12 months (p = 0.005) and to 109 μg/g
at 18 months (p = 0.004)), whereas patients in endoscopic remission who did not
step up medical therapy had increasing fCal concentrations (from 129 to 153 μg/g
at 12 months (p = 0.194) and to 178 μg/g at 18 months (p = 0.245)) [ 15 ]. This sug-
gests that fCal may also serve as a noninvasive, indirect measure of treatment
response in treatment of POR.
C-Reactive Protein
The utility of serum inflammatory marker C-reactive protein (CRP) in predicting
POR has been analyzed in several studies with discordant results. Boschetti et al.
collected CRP data in their 86 asymptomatic postoperative CD patients and found a
weak but significant difference in CRP concentrations between patients with endo-
scopic remission and endoscopic recurrence (3.0 ± 0.7 and 8.5 ± 1.4 mg/L, respec-
tively; p = 0.001) [ 13 ]. Furthermore, a significant increase of CRP levels according
to Rutgeerts score was also observed (ptrend = 0.02), but without significant differ-
ences between individual subscores. When compared to fCal, CRP was less accu-
rate (53% vs. 77% for fCal) in predicting endoscopic recurrence, and the area under
the curve for fCal was 0.86 compared to <0.70 with CRP suggesting fCal as the
superior testing modality. Conversely, in the same randomized control trial for step-
up medical therapy following surgical resection in CD patients, Wright et al. also
collected CRP data and found that CRP was not significantly correlated with endo-
scopic recurrence (Rutgeerts i2–i4) or scored endoscopic severity (i0–i4) [ 15 ].
Given the conflicting results, further studies are needed on the utility of CRP in
predicting endoscopic and clinical recurrence postoperatively.
Ultrasound
Noninvasive radiographic studies including abdominal ultrasound have also been
investigated in detecting POR. A study of traditional transabdominal ultrasound
(TUS) in 32 CD patients who had undergone one or more intestinal resections
B.H. Click and M. Regueiro