Can Intra-Operative Doppler Ultrasound Predict Anastomotic Leakage After Rectal Cancer Surgery?

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Can Intra-Operative Doppler Ultrasound Predict Anastomotic Leakage After Rectal Cancer Surgery? A Pilot Study

Anastomotic leakage (AL)—a serious complication where the surgical connection (anastomosis) between the remaining colon and rectum fails—affects 4–20% of patients after rectal cancer surgery. It’s linked to infections, reoperations, and long-term health issues, yet surgeons lack reliable tools to predict who will develop it. Now, a 2019 pilot study suggests that intra-operative Doppler ultrasound—a non-invasive way to measure blood flow—could help identify patients at high risk of AL, guiding better surgical decisions.

What the Study Did

The research, led by Dr. Chang-Zheng Du (Peking University Cancer Hospital) and colleagues from Duke University Medical School and Peking-Tsinghua Joint Center for Life Sciences, enrolled 163 patients with rectal cancer who underwent sphincter-preservation surgery (a procedure that saves the anus) between 2011 and 2015. All patients had a “low-ligation” procedure: surgeons preserved the main artery to the colon (inferior mesenteric artery) to maintain blood flow, then ligated smaller arteries (sigmoid or left colic) to get enough colon length for a tension-free anastomosis.

During surgery, the team used Doppler ultrasound to measure blood flow in the colon near the anastomosis before and after ligating those smaller arteries. They tracked five key hemodynamic parameters:

  • Peak systolic velocity (PSV): Maximum blood flow speed (reflects blood perfusion).
  • Pulsatility index (PI): Regularity of blood flow (higher = more uneven flow).
  • Resistance index (RI): Vessel resistance (higher = narrower vessels).

The “residual rate”—how much blood flow remained after ligation—was critical: a lower rate meant poorer blood supply to the anastomosis.

Key Findings

Overall, 15 patients (9.2%) developed AL. The study found:

  1. Poor blood supply = higher leakage risk: Patients with a PSV or PI residual rate below 60% (classified as “poor” blood supply) were 5 times more likely to leak (19.6% vs. 3.7% for “good” supply, P=0.003).
  2. High-risk subgroups:
    • Low rectal cancer: Patients with tumors within 6 cm of the anus had a 25.9% leakage rate with poor blood supply vs. 3.9% with good supply (P=0.007).
    • Neoadjuvant chemoradiotherapy: Patients who had pre-surgery radiation and chemo faced a 32.1% risk with poor blood supply vs. 3.7% with good supply (P=0.001).
  3. Independent risk factors: After adjusting for other variables (e.g., tumor location, ileostomy), two factors stood out:
    • Poor anastomotic blood supply (odds ratio: 10.37).
    • Neoadjuvant chemoradiotherapy (odds ratio: 5.92).

Why This Matters for Surgeons and Patients

Surgeons currently judge blood supply by visible pulsation in the colon—a subjective method that’s often inaccurate (especially in obese patients). Doppler ultrasound offers a quantitative, objective measure that takes just 15–20 minutes and poses no extra risk to patients.

For patients, this could mean:

  • Fewer unexpected complications after surgery.
  • Avoiding unnecessary protective ileostomies (temporary stomas that require a second surgery to close).
  • More personalized care: Surgeons could use Doppler results to decide whether to adjust the anastomosis, perform a different procedure (like Hartmann’s surgery), or prioritize close monitoring for high-risk patients.

Limitations and Next Steps

The study has caveats:

  • It was a single-center pilot study with a small sample (163 patients), so results need validation in larger, multi-center trials.
  • Researchers couldn’t measure blood flow in the rectal stump (the remaining rectum), which is another key part of the anastomosis. Previous studies show total mesorectal excision (TME)—a standard part of rectal cancer surgery—can reduce blood flow to the stump, so including this in future models could improve prediction.

Conclusion

While more research is needed, this study suggests Doppler ultrasound could become a routine tool in rectal cancer surgery to predict AL. By focusing on blood supply—one of the most critical factors for anastomotic success—surgeons could reduce complications and improve outcomes for patients.

The original study was published in the Chinese Medical Journal in 2019 by Du et al. You can access it at doi.org/10.1097/CM9.0000000000000410.

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