Retrospective observational study on the incidence of incisional hernias after colorectal carcinoma resection with follow-up CT scan

Incisional hernia (IH) is the most frequent complication after colorectal carcinoma (CRC) resection. The incidence depends on the method of follow-up, where ultrasound yields a significant number of additional hernias compared to clinical examination alone. Not many studies have evaluated the value of computed tomography (CT) to diagnose IH. The CorreCT study is a retrospective cohort study of IH after CRC surgery by clinical examination and by CT, as reported in the medical files. Additional independent reviewing of all CTs by two radiologists was performed. From the oncological database (2004-2008) of the hospital, 598 patients with CRC were identified. The data of 448 consecutive patients who underwent surgery were analyzed. Tumors were resected by laparotomy in 366 patients (81.7 %), by laparoscopy in 76 patients (17.0 %) and by laparotomy after conversion in 6 patients (1.3 %). A clinical follow-up by the surgeon in 282 patients (62.9 %) with a mean duration of 33 months, yielded 49 patients with IH (17.4 %). The mean time of IH diagnosis (T1) was 19 months. Only 16 patients (33 %) underwent a hernia repair. For 363 patients (81.0 %), CT follow-up was available for a mean period of 30 months. In 84 patients (23.1 %), an IH was diagnosed with a mean T1 of 21 months. The review of all CTs by two independent radiologists yielded additional IH in 19 and 21 patients, respectively, increasing the IH rate to 29.1 and 29.7 %, respectively, and with a decrease in mean T1 to 14 months. The inter-observer agreement between the radiologists had a Kappa-statistic of 0.73 (95 % CI 0.65-0.81). For those patients with disagreement between the radiologists, a final agreement was made during an additional reviewing session of both radiologists, increasing the IH rate to 35.0 %. Comparing clinical follow-up, routine CT follow-up, and reassessed CT follow-up we found a statistically significant difference between the three methods of IH detection (p < 0.0001). CT follow-up can identify significantly more IH than clinical examination alone, in particular if the radiologist focuses on IH development. Furthermore, we showed that focused CT evaluation diagnosed IH 7 months earlier than routine CT and 5 months earlier than clinical follow-up alone.