Comparison of DS and RNY

To follow is a comparison of DS and RNY bariatric procedures. We explain the biological differences in your anatomy, how the changes affect your body and the impact they could have on your lifestyle. Since Roux-en-Y Gastric Bypass (RNY) and Duodenal Switch (DS) both contain restrictive and malabsorption components, we will examine those differences then compare excess weight loss long term and resolution of comorbidities in both procedures.

Restrictive Component

RNY

The "pouch" stomach is 10 - 30 mL in volume immediately following surgery [51] but can stretch over time; after a few years it may hold 8 - 10 oz. To prevent stretching the stoma it is recommended to measure your food portions, eat very slowly and rigorously chew your food.

Weight maintenance is achieved through caloric restriction.

Dumping
"Early" dumping begins during or right after a meal and symptoms include nausea, vomiting, bloating, cramping, diarrhea, dizziness and fatigue. "Late" dumping happens 1 to 3 hours after eating and symptoms include weakness, sweating, and dizziness. Some patients choose RNY surgery because they prefer the possibility of "dumping" to help them control eating junk food containing sugar or fat. Approximately 70%-76% of patients dump. [60-64] Patients dump with different foods, some never dump, some only on certain quantities, some "outgrow" it.

Ulcers
Standard diagnostic techniques can be used on the "pouch" stomach. The "blind" stomach is inaccessible to standard non-evasive diagnostic tools like x-ray and endoscope. It makes it extremely difficult for a doctor to find and treat ulcers.

"Normally if a patient develops ulcer symptoms, a gastroenterologist can look into the stomach with an endoscope and make the diagnosis of an ulcer. If that ulcer is bleeding, the gastroenterologist can also treat the ulcer to stop it from bleeding by injecting a drug into it or putting some electric current on the ulcer to coagulate it. These options are taken away once you have a RNY bypass". [59] The blind stomach can be scoped, by placing the patient under anesthesia, making a small incision on the abdomen, and advancing the scope through the incision into the blind stomach.

The tissue at the anastamosis between the stomach and small intestine has lost some of its blood supply and is therefore more fragile, and thus at increased risk of ulceration. Smoking will increase the risk of ulceration in the anastamosis area.

NSAIDs
Taking Aspirin or non-steroidal anti-inflammatory drugs (NSAIDs) causes increased risk for ulcers. Since diagnosing and treating ulcers is so difficult in RNY patients and due to the fragile state of the anastamosis, many surgeons do not recommend RNY patients take NSAIDs following surgery. NSAIDs include Ibuprofen (Advil, Motrin), Naproxen (Naprosyn, Aleve) etc.

DS

A benefit of removing a portion of the stomach is that it also greatly reduces the amount of ghrelin producing tissue and the amount of acid. Ghrelin is the "hunger hormone" and reducing the amount produced suppresses the appetite.

The remaining stomach is about 3-5 oz or holds approx 90 to 150mL in volume. After DS patients can consume a wide variety of foods and after about a year can consume approx half of their preoperative volume. [2]

A DS patient's stomach tends to be bigger than RNY and Lap Band patients. The reason is that DS weight loss is maintained through malabsorption rather than caloric restriction and because of the increased protein requirement (since 40% is malabsorbed) more room is needed to consume 100 grams of protein a day. DS patients don't dump because their pylorus remains in use, so there are no food's they "can't" eat. With this freedom comes responsibility, patients need to eat protein based meals following surgery to stay healthy.

Some patients choose DS surgery because they prefer unrestricted food options or because they need to continue taking NSAIDs.

Malabsorption Component

RNY

• Vitamin and mineral supplementation is vital and a requirement to maintaining good health.
  

• Routine blood work is mandatory. Adjust supplements as necessary.

Basic vitamin requirements - multivitamin, calcium citrate, B12, B1, iron

DS

• Only absorb 20% of the fat you consume. Eating too much fat can cause loose stools. The inability to absorb fats also interferes with absorption of the fat-soluble vitamins A, D, E & K.
  

• Only absorb approx 60% of the protein you consume. You must intake between 80-120g of protein a day.
  

• Only absorb 60% of complex carbohydrates and 100% of simple carbohydrates.
  

• Gas and stool tend to be stronger smelling due to the intestine re-routing and can be enhanced if you eat too many simple carbs.
  

• Vitamin and mineral supplementation is vital and a requirement to maintaining good health.
  

• Routine blood work is mandatory. Adjust supplements as necessary.

Weight maintenance is achieved through malabsorption. The malabsorption component is attributed to the higher % excess weight loss (EWL) long term when compared to other bariatric procedures.

Basic vitamin requirements - multivitamin, calcium citrate, vitamin A, vitamin D, zinc

Excess Weight Loss (EWL)

RNY

DS

Resolution of Comorbidities

RNY

DS

The Duodenal Switch weight loss surgery procedure has seen the highest rate of type 2 diabetes cure, often before leaving the hospital following surgery! For more information on how DS surgery can have such a quick result see the metabolic effect in our section on the Duodenal Switch Procedure.

Additional Comparisons