Assessment and Management

Introduction

Bariatric surgery refers to a group of operations aimed at achieving weight loss in individuals with obesity. Surgical intervention may be considered when conservative approaches, such as dietary modification, increased physical activity, or pharmacological support, have failed to achieve sustained weight reduction.

Obesity is a chronic multifactorial disease characterised by an excess body fat. Global rates of obesity are increasing; in the UK, 1 in 4 adults are now classified as obese. Clinically, obesity is defined as a Body Mass Index (BMI) of ≥30 kg/m².

Its impact on health can be profound, contributing to co-morbidities including type 2 diabetes mellitus (T2DM), hypertension, coronary artery disease, certain cancers, obstructive sleep apnoea (OSA), non-alcoholic fatty liver disease (NAFLD), and osteoarthritis.

Indications for Surgery

Variation exists globally as to when a patient is recommended to undergo bariatric surgery.

According to NICE guidance, patients may be referred for bariatric surgery assessment if they fulfil the following criteria:

• Body Mass Index (BMI) ≥ 40 kg/m² or BMI ≥ 35 kg/m² with other significant comorbidities that may improve with weight loss (e.g. T2DM, OSA, hypertension, NAFLD)
• Participation in, or planned enrolment in, a Tier 3 specialist weight management service (Fig. 1)
• The patient is deemed fit for anaesthesia and surgery
• Demonstrate commitment to long-term follow-up and lifestyle modification

By TeachMeSeries Ltd (2025)

Figure 1 – Pyramid of Obesity Management Services

Pre-Operative Considerations

All patients undergo a thorough multidisciplinary assessment to evaluate their suitability for bariatric intervention. This process typically involves input from dieticians, specialist nurses, psychologists, surgeons, and anaesthetists.

Aspects of the assessment include screening for nutritional deficiencies, reviewing and optimising co-morbidities, and education of post-operative expectations and commitment to follow-up and lifelong dietary supplementation.

Smoking cessation and alcohol reduction are also encouraged in the peri-operative period to optimise outcomes and reduce surgical risk.

Procedures

The main bariatric procedures currently used worldwide include (covered in more detail here):

• Sleeve gastrectomy
• Roux-en-Y gastric bypass
• Gastric banding
• Biliopancreatic diversion and duodenal switch

Procedure selection is individualised based on patient factors, co-morbidities, and institutional expertise.

Following surgery patients require early mobilisation and close monitoring for complications. Enhanced recovery protocols are commonly used to facilitate a safe and efficient recovery. Dietary intake should be managed in stages, starting with liquids and advancing to solids over several weeks under guidance of a specialist dietician.

Potential complications from bariatric procedures include early post-operative issues (e.g. anastomotic leak or infection) and late complications (e.g. internal hernia, gallstone disease, and nutritional deficiencies).

Long Term Follow-Up

Bariatric surgery should be viewed as one part of a comprehensive approach to long-term weight management. Success depends not only on surgical procedure but also on the patient’s adherence to lifestyle modifications and engagement with follow-up care.

Patient follow-up post-operatively should include support from the bariatric multidisciplinary team for a number of years, after which ongoing care is transitioned to primary care. This includes lifelong nutritional surveillance, routine bloods tests to monitor for micronutrient deficiencies, continued weight and co-morbidity monitoring and adherence to dietary supplementation.