This study was approved by the ethical review board of the Shinshu Ueda Medical Center, and the need for informed consent from patients was waived. We retrospectively reviewed the medical records of patients who underwent digestive surgeries at Shinshu Ueda Medical Center from April 2018 to March 2019, attended by anesthesiologists (general anesthesia, neuraxial anesthesia, and local anesthesia). We excluded the following patients from the study: patients who already had PE or DVT on admission, and those who underwent a second operation during the hospital stay. We collected the following data: disease, operation method, age, sex, American Society of Anesthesiologist’s Physical Status (ASA-PS), body mass index, operative time, D-dimer value (preoperatively, postoperatively within 24 hours, and on the following days), and DVT/PE diagnosis. Continuous data are presented as mean (25th to 75th percentiles).
Diagnosis of DVT/PE
DVT/PE was confirmed with enhanced CT scan when the plasma D-dimer value exceeded approximately 10 μg/ml. Enhanced CT scanning was performed with a 64-row multidetector scanner (Aquilion64; Canon Medical Systems Corporation, Ohtawara, Japan). A total non-ionic contrast material volume of 80 to 100 ml (iodine concentration, 300–370 mg/ml) was injected at the rate of 2.4 to 3.0 ml/s according to the patient’s weight. For pulmonary embolism, the scanning was started at 25 s after the start of injection, and the whole lung area was assessed. For deep venous thrombosis, the scanning was started at 210 s after the start of injection and the region from the diaphragm to the toes was investigated. In both areas, data were acquired with 0.5 mm thickness scans, and reconstructed for 2.0 mm-slice axial images, 5 mm-slice sagittal images, and 5 mm-slice coronal images. CT images were reviewed by a radiologist and the patient was accordingly diagnosed with DVT/PE. If a patient had any symptom of DVT/PE, we performed enhanced CT immediately, regardless of the D-dimer value. When the plasma D-dimer value did not exceed approximately 10 μg/ml and there were no symptoms, we performed physical examination and ultrasonography, if necessary, for observation.
Studies
We reviewed the seven DVT/PE cases with acute appendicitis, including their symptoms, plasma D-dimer values, and CT findings.
We compared the incidence of DVT/PE between acute appendicitis and other disease categories. Then, we compared the background data (operative time and age) between patients with acute appendicitis and those with colorectal cancer, as asymptomatic DVT/PE incidence among colorectal cancer patients had been well studied [6, 7], and the number of operated cases are much higher in colorectal cancer than in other cancers. We thought DVT/PE incidence among colorectal cancer patients may provide a benchmark.
We further analyzed and compared the two categories of acute appendicitis, namely, complicated appendicitis and simple appendicitis. Categorization was made by intraoperative findings or postoperative pathological findings. We compared the incidence of DVT/PE, preoperative inflammatory biomarker (WBC, CRP, and Body temperature) levels, and plasma D-dimer values (preoperative and postoperatively within 24 h) between the two categories.
Statistical analysis
The EZR (Saitama Medical Center, Jichi Medical University, Saitama, Japan) was used for statistical analyses. We compared the incidence of DVT/PE using the Fisher test with the Bonferroni post hoc test. We calculated the confidence interval of DVT/PE incidence with the Clopper-Pearson method. Continuous data were compared using the Mann-Whitney U test. P < 0.05 was considered statistically significant.