The goal of this observational study is to learn about intestinal microbiome structure and function in individuals who have undergone a pancreatoduodenectomy and compare to healthy matched controls.

The primary objectives of the study are:

1. To explore and describe any differences in the gut microbiota especially Shannon diversity index
2. To conduct functional profiling by exploring and describing any differences in functional metabolites produced in the gut in people having had pancreatoduodenectomy greater than 6 months ago compared to healthy matched controls.

Participants will be asked to complete the following:

• Three-day food, bowel and medication diary (see Protocol appendix 5)
• Gastrointestinal Symptom Rating Scale (see Protocol appendix 6)
• Quality of life questionnaire (see Protocol appendix 7)
• Stool sample test using Microba Insight TradeMark (a small swab is taken from soiled toilet paper, sealed in a room-temperature storage capsule and mailed to the testing laboratory)

Inclusion Criteria:

• Adults (aged equal to or greater than 18 years) having had pancreatoduodenectomy (Whipple's) surgery between April 2018 - December 2023 for curative intent and received post-operative clinical management at Royal Prince Alfred Hospital, (post-surgical participants), and
• Healthy adults matched by age, sex, body mass index and smoking status

Exclusion Criteria:

• Aged less than 18 years
• Are unable to complete the questionnaires or testing due to language or cognitive limitations
• Have active or recurring pancreatic cancer, or where the surgery was for non-curative intent
• Have other gastrointestinal conditions that could affect gut symptoms or microbiome such as Inflammatory Bowel disease, Irritable Bowel Syndrome Coeliac disease, or are currently pregnant or breastfeeding
• Are currently taking medications or diet that can affect gut symptoms or microbiome

Post-surgical patients are adults (aged ≥ 18 years) who have undergone a pancreatoduodenectomy (Whipple's) surgery for curative between the time period of April 2018 - December 2023, and received post-operative clinical management at Royal Prince Alfred Hospital. Healthy adults (matched controls) will be matched by age, sex, body mass index and smoking status.