Value of Intra-Operative Doppler Sonographic Measurements in Predicting Post-Operative Anastomotic Leakage in Rectal Cancer: A Prospective Pilot Study
Anastomotic leakage (AL) remains one of the most serious complications following low anterior resection (LAR) for rectal cancer. It is associated with high post-operative mortality and poor oncological outcomes. The incidence of AL varies between 4% and 20%, influenced by factors such as surgical technique, neoadjuvant therapy, tumor location, sex, and intestinal bacterial infections. Despite the identification of several clinical risk factors, accurately predicting AL in individual patients remains challenging. Current methods rely on clinical judgment and risk factors, which are not always reliable. This study aimed to develop a quantitative method using intra-operative Doppler sonographic hemodynamic measurements to predict the risk of AL.
The study was conducted at Peking University Cancer Hospital from April 2011 to January 2015. A total of 163 patients with rectal cancer who underwent anterior resection and low-ligation procedures were prospectively recruited. The inclusion criteria included histopathologically confirmed adenocarcinomas with the inferior margin within 12 cm from the anal verge, resectable lesions evaluated by magnetic resonance imaging or endorectal ultrasound, and scheduled sphincter-preservation surgery without clinical evidence of synchronous distant metastases. Patients with arteriosclerosis, diabetes mellitus, arrhythmia, pre-operative bowel obstruction, or malnutrition were excluded. The study was approved by the Ethics Committee of Peking University Cancer Hospital, and informed consent was obtained from all participants.
All patients underwent LAR according to total mesorectal excision (TME) principles. Pelvic autonomic nerves were preserved as much as possible, and lateral pelvic lymphadenectomy was performed if necessary. The low-ligation procedure involved the division of the superior rectal artery (SRA) distally to the origin of the left colic artery (LCA), with subsequent en bloc excision of the lymph nodes and bowels below it. The sigmoid artery (SA) or a branch of the LCA was then ligated to prolong the proximal colon limb for a tension-free colorectal anastomosis. The double-stapling technique was used, and an air leakage test was performed in all patients. Prophylactic ileostomy was constructed based on the surgeon’s discretion.
Doppler hemodynamic measurements were recorded before and after vascular ligation at the same site near the anastomotic bowel. The measurements started after the anvil was fixed in the colon and repeated after the ligation of the SA or LCA. Duplex Doppler sonography was conducted using an ultrasound device equipped with a linear probe of 5 to 10 MHz. The chief operator identified the blood flow signal by placing the sonographic probe on the mesenteric border of the bowel wall. Doppler hemodynamic parameters, including peak systolic velocity (PSV), end-diastolic velocity (EDV), mean velocity (MnV), pulsatility index (PI), and resistance index (RI), were recorded. The residual rate of each parameter was calculated as the post-ligation value divided by the pre-ligation value multiplied by 100%.
The overall incidence of AL was 9.2% (15/163). Doppler hemodynamic parameters whose reduction was significantly associated with AL were PSV, PI, and RI. The areas under the receiver operating characteristic (ROC) curve of residual rates of PSV, PI, and RI in predicting AL were 0.703, 0.729, and 0.689, respectively. The predictive model revealed that patients with severely reduced blood-flow signal exhibited a significantly higher incidence rate of AL than those with sufficient blood supply (19.6% vs. 3.7%, P = 0.003). This was particularly evident in patients with low rectal cancer (25.9% vs. 3.9%, P = 0.007) and those receiving neoadjuvant chemoradiotherapy (32.1% vs. 3.7%, P = 0.001), independent of prophylactic ileostoma. Multivariate analysis revealed that insufficient blood supply of the anastomotic bowel was an independent risk factor for AL (odds ratio: 10.37, 95% CI: 2.703–42.735, P = 0.001).
The study demonstrated that intra-operative Doppler sonographic hemodynamic measurement of the anastomotic bowel has potential value in predicting AL. The predictive model based on hemodynamic parameters, particularly PSV and PI, was effective in identifying patients at high risk of AL. This method could be used to guide surgical decision-making, particularly in determining the necessity of defunctioning ileostomy. The findings suggest that Doppler sonography provides a quantitative and reliable assessment of anastomotic blood supply, which is crucial for reducing the risk of AL.
The study also highlighted the importance of blood supply in the context of low-ligation procedures. Although the low-ligation procedure preserves the inferior mesenteric artery (IMA), ligation of the SA or LCA branches can still compromise blood supply in some patients. The absence or malfunction of the marginal arcade may contribute to this reduction in blood supply. Patients with low rectal cancer and those receiving neoadjuvant chemoradiotherapy were found to be more vulnerable to insufficient anastomotic blood supply, making the predictive model particularly useful in these cases.
The use of Doppler sonography in this study provided detailed hemodynamic information and sonographic images, making it a promising tool for intra-operative assessment. The method is convenient and does not pose additional hazards to patients. However, it requires surgeons to modify their operating steps to allow for the collection of hemodynamic parameters before and after vascular ligation. The study also noted that evaluating the blood supply of the rectal stump was not feasible with the current technique, which could be a limitation in assessing the overall blood perfusion of the anastomosis.
In conclusion, this study demonstrated that intra-operative Doppler sonographic hemodynamic measurement is a promising method for predicting AL in patients undergoing LAR for rectal cancer. The predictive model based on hemodynamic parameters, particularly PSV and PI, can effectively identify patients at high risk of AL and guide surgical decision-making. The findings suggest that Doppler sonography provides a quantitative and reliable assessment of anastomotic blood supply, which is crucial for reducing the risk of AL and improving patient outcomes. Future studies with larger populations and multi-center validation are needed to further confirm the utility of this method.
doi.org/10.1097/CM9.0000000000000410
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