Definition and classification of chyle leak after pancreatic operation: A consensus statement by the International Study Group on Pancreatic Surgery
Executive Summary
Chyle leak (CL) is a recognized complication of pancreatic resection, with recent literature suggesting an incidence of up to 10%. Historically, the absence of a standardized international definition or grading system has hindered the comparison of outcomes across different surgical series. To address this, the International Study Group on Pancreatic Surgery (ISGPS) developed a universal, objective definition and a three-tier severity grading system based on a systematic literature review and expert consensus.
Key Findings:
Standardized Definition: CL is defined as the output of milky-colored fluid from a drain, drain site, or wound on or after postoperative day 3, with a triglyceride content ≥ 110 mg/dL (≥ 1.2 mmol/L).
Grading System:
Grade A: No specific intervention required beyond oral dietary restrictions; no prolongation of hospital stay.
Grade B: Requires nasoenteral nutrition, TPN, octreotide, or maintenance of drains; leads to prolonged hospital stay.
Grade C: Requires invasive treatment (interventional radiology or reoperation), ICU admission, or results in mortality.
Clinical Impact: While 95% of cases are successfully managed non-operatively, CL can lead to malnutrition, immune compromise, and extended hospitalization.
Methodological Quality of Evidence
The ISGPS consensus was derived from a systematic search of PubMed and Cochrane databases. Of the 505 records identified, 14 studies were selected for qualitative synthesis.
Overview of Chyle Leak in Pancreatic Surgery
Chyle is a lymphatic fluid rich in triglycerides (chylomicrons) transported from the intestinal wall to the venous circulation via the cisterna chyli and the thoracic duct. During pancreatic resections—particularly pancreatoduodenectomies—the cisterna chyli and its major branches, located anterior to the first and second lumbar vertebrae, are susceptible to injury.
The clinical consequences of a chyle leak include:
Malnutrition: Loss of essential lipids and proteins.
Immunological Impact: Potential progression to an immunocompromised state.
Recovery Delay: Increased duration of abdominal drainage and hospital stay.
The ISGPS Consensus Definition
Prior to the ISGPS consensus, definitions of CL varied significantly regarding volume thresholds (ranging from 100 mL to 600 mL per day) and triglyceride concentrations. The ISGPS concluded that clinical relevance, rather than a specific volume threshold, should define the complication.
Criteria for Diagnosis
A diagnosis of chyle leak is confirmed when the following conditions are met:
Timing: Output occurs on or after postoperative day 3.
Appearance: Fluid is milky-colored (or creamy).
Biochemical Marker: Triglyceride content is ≥ 110 mg/dL (≥ 1.2 mmol/L).
Note: In centers that measure chylomicrons instead of triglycerides, the presence of chylomicrons is considered equivalent to the triglyceride threshold.
Severity Grading System
The ISGPS grading system classifies the severity of CL based on the intensity of management required and the impact on the patient’s clinical course.
Clinical Incidence and Risk Factors
A review of 14 studies involving 7,574 patients undergoing pancreatic resection revealed a pooled incidence rate of 3.0%, though individual studies reported rates as high as 16%.
Independent Risk Factors
The consensus identified several factors that increase the likelihood of developing CL:
Surgical Dissection: Para-aortic area dissection, root of the superior mesenteric artery dissection, and the extent of lymph node dissection.
Pathological Factors: Presence of retroperitoneal invasion, lymphovascular invasion, and chronic pancreatitis.
Treatment Factors: Neoadjuvant therapy and vascular resection.
Nutritional Factors: Early enteral feeding was identified in three studies as an independent risk factor for the onset of CL.
Patient/Postoperative Factors: Female sex and postoperative portal or mesenteric venous thrombosis.
Management and Therapeutic Outcomes
Management of CL typically begins once the complication is recognized, usually at a median of 5–6 days postoperatively. The pooled success rate for treatment across documented studies is 95%.
Primary Treatment Modalities
Dietary Restrictions: Initial management focuses on reducing lymph flow.
Low-fat/Fat-free diets: Restricting long-chain triglycerides.
Medium-Chain Triglycerides (MCT): Often introduced because MCTs are absorbed directly into the mesenteric venous circulation rather than the lymphatic system, providing necessary calories without increasing chyle flow.
Total Parenteral Nutrition (TPN): Used when dietary measures fail or to completely bypass the gut.
Pharmacotherapy: Use of somatostatin analogues (e.g., octreotide) to decrease intestinal secretions and lymph flow.
Invasive Interventions (Grade C)
In rare cases where conservative management fails, more invasive options include:
Lymphatic Embolization/Sclerosis: Guided by interventional radiology.
Peritoneovenous Shunt: Decompressing chyle into the systemic circulation.
Operative Ligation: Reoperation to identify and ligate the site of the leak, often facilitated by lymphangiography.
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