Portomesenteric Venous Thrombosis Following Major Colon and Rectal Surgery: Incidence and Risk Factors.

Kristin A Robinson, MD, Mark E O’Donnell, MD, David G Pearson, MD, Melanie E Odeleye, MD, Zachary Bodnar, MD, Kristen A Kalkbrenner, PAC, J. Scott Kriegshauser, MD, Tonia M Young-Fadok, MD. Mayo Clinic Hospital, Arizona.

Introduction: Portomesenteric venous thrombosis (PMVT) is a rare and potentially fatal complication of abdominal surgery. Current risk factor stratification models for PMVT following colon and rectal surgery are lacking. Pneumoperitoneum during laparoscopic procedures has been suggested to precipitate PMVT more frequently than open procedures due to alterations in portovenous blood flow. The main objective of this study was to assess PMVT risk factor profiles and patient outcome after major colorectal surgery.

Methods: A single center retrospective review of all patients undergoing colon and rectal surgery was performed from 2007 to 2012. Patient demographics, clinical history, perioperative thromboprophylaxis regimen, operative procedure and clinical outcomes were reviewed from electronic medical records. PMVT was defined as thrombus within the portal, hepatic or superior mesenteric veins. Inferior mesenteric vein thrombosis was excluded. Independent samples T-test was used to compare data variables between PMVT and non-PMVT patients. Univariate and multivariate logistic regression analyses were used to assess the effect of clinical characteristics on PMVT risk.

Results: 1224 patients were included (mean age 61.6 years, male=566). Bowel resection was performed electively for colon carcinoma (n=302), rectal carcinoma (n= 112), ulcerative colitis (n=125), Crohn’s disease (n=78), polyps (n=117), diverticulitis (n=215) or during gynecological resections and emergent laparotomies (n=275). 213 patients had BMI > 30 kg/m2. 108 patients were current smokers. 337 (27.5%) patients were taking pre-operative antithrombotic therapies. 1025 (83.7%) received both routine pre and post-operative DVT chemoprophylaxis. Thirty-six patients (2.9%) were diagnosed with PMVT by computed tomography at a mean time of 13.9 days post-procedure (range 3-69 days): 17/36 on initial presentation and 19/36 by expert radiologist review. Patients with PMVT were significantly younger (52.7 vs. 61.9 years, p=0.001) with higher BMI (30.5 vs. 26.7, p<0.001) and maximum platelet levels (464 vs. 306, p<0.001) compared to patients without PMVT. However, both patient groups were otherwise matched for clinical and surgical variables including cancer diagnosis (PMVT: 13/36=36.1% vs. non-PMVT: 462/1188=38.9%, p=0.73). Univariate logistic regression identified younger age (p<0.001), higher BMI (p<0.001), ulcerative colitis (p<0.001), higher maximal platelet levels (p<0.001) and proctocolectomy as significant predictors of PMVT. Stepwise multivariate logistic regression identified that higher BMI (p<0.001), higher platelet levels (P<0.001) and proctocolectomy (p=0.001) were still significant predictors. However, gender, smoking, pre-operative antithrombotic treatment, indication for surgery, open or laparoscopic surgical approach and subsequent pneumoperitoneum pressure, peri-operative blood transfusion, and length of surgery were not significant predictors. No patients in the PMVT group suffered bowel infarction or required surgical intervention. Currently 1043 patients are alive with mean follow up of 42.5 months where 1 of 36 PMVT patients died and 180 of 1188 non-PMVT patients died (2.8% vs. 15.2%, p=0.039).

Conclusion: Higher BMI, higher platelet levels, and proctocolectomy were significant predictors of PMVT in multivariate analysis. Proctocolectomy may be a marker for ulcerative colitis and younger age, which were significant in univariate analysis. Laparoscopic approach was not a risk factor in either univariate or multivariate analysis. The significantly higher mortality rate in non-PMVT patients was an unexpected finding and further analysis is indicated.

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