Why do Patients Develop Pernicious Anemia after a Gastrectomy?

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Doctors perform gastrectomy in the patient

Overview

Gastrectomy is the surgical removal of a portion or all of the stomach. Gastrectomy is used to treat problems in the stomach that cannot be cured by other treatments. The doctor may recommend gastrectomy to treat:

  • Benign or distal tumors
  • Benign gastric ulcers disease
  • Inflammation
  • Bleeding
  • Perforations in the stomach wall
  • Severe duodenal or peptic ulcers
  • Polyps or growth inside the stomach
  • Esophageal cancer
  • Stomach cancer

Gastrectomy can also be used to treat obesity. Gastrectomy makes the stomach smaller allowing it to fill more quickly. This helps a person eat less. Gastrectomy is only used to treat obesity if all other options for treatment have failed such as diet, exercise, counseling, and medication.

How Gastrectomy is Performed

There are two ways to perform gastrectomy and both are performed under general anesthesia:

  • Open Surgery

Open surgery involves a single large incision. The surgeon pulls back the muscle, tissue, and skin to access the stomach.

  • Laparoscopic Surgery

Laparoscopic surgery is a minimally invasive surgery that involves small incisions and specialized tools. This procedure is usually preferred to open surgery because it is less painful and it has a quicker recovery time. The surgery is more advanced and it also has a lower rate of complications.

The surgeon may recommend open surgery over laparoscopic surgery to treat stomach cancer.

Types of Gastrectomy

There are four types of gastrectomy:

1.Partial Gastrectomy

In partial gastrectomy, the surgeon only removes the lower half of the stomach. The lymph nodes nearby may also be removed in the event that cancer cells are found in them. The surgeon closes off the duodenum, the first part of the small intestine that receives food that is partially from the stomach. The remaining part of the stomach is connected to the bowel.

2.Complete or Total Gastrectomy

Incomplete gastrectomy, the surgeon completely removes the stomach. The esophagus is connected directly to the small intestine.

3.Sleeve Gastrectomy

Up to three-quarters of the stomach, usually, the left side, may be removed. The surgeon trims the side of the stomach and turns it into a tube shape. It creates a smaller but longer stomach.

4.Esophagogastrectomy

The surgeon removes the part of the esophagus and the top part of the stomach.

Complications of Gastrectomy

Gastrectomy is an effective treatment for obesity and cancer although it poses some risks for complications. It can cause internal bleeding, infection, stricture, acid reflux, nausea, vomiting, and leaking from the part that has been stitched together. It may also result in osteoporosis and anemia because of the body’s reduced ability to absorb vitamins, minerals, and other nutrients needed by the body to be able to function properly.

Normally, the top portion of the stomach is connected to the esophagus and the bottom part of the stomach is connected to the small intestine or duodenum. During surgery, the esophagus is connected either to the small intestine or the remaining part of the stomach. It means that the digestive system will still work but it won’t function the way it did before.

One of the functions of the stomach is to absorb vitamins and minerals such as vitamins B12, C, D, iron, and calcium from the foods that you eat. With the removal of part of the whole stomach, your body may not be getting all the vitamins and minerals that it needs from your food intake. This may result in certain health conditions like anemia, vitamin B12 deficiency, and osteoporosis.

Anemia

Anemia is frequently diagnosed in patients who have undergone gastrectomy because of iron deficiency. Iron deficiency and anemia have a higher incidence rate for patients who have undergone total gastrectomy compared to the ones who have had subtotal gastrectomy. It is caused by a problem in absorbing iron. Iron is absorbed in the proximal jejunum and duodenum and the secretion of gastric acid enhances the absorption of iron. Since the gastrointestinal tract is altered during surgery, the body absorbs little iron and impairs the secretion of gastric acid. With little gastric acid, the ingested ferric iron has a problem in converting into absorbable ferrous iron. Both these factors contribute to the development of anemia.

Vitamin B12 Deficiency and Pernicious Anemia

Vitamin B12 deficiency is a result of the malabsorption of vitamin B12 through the intestine. Vitamin B12 deficiency as a consequence of gastrectomy usually develops after several years compared to the onset of anemia because vitamin B12 is stored in the liver and the deficiency does not occur until all the stored vitamin B12 have been depleted. The iron that the body stores are more limited compared to that of vitamin B12 that’s why iron deficiency anemia occurs earlier and more frequently in patients who have undergone a gastrectomy.

Given that gastrectomy can lead to vitamin B12 deficiency, gastrectomy can also affect the production of Intrinsic Factor. When the proximal stomach is resected or if the cells of the stomach lining are not able to produce Intrinsic Factor as an effect of gastrectomy, pernicious anemia is developed by the patient. The lack of Intrinsic Factor is the main cause of pernicious anemia because it is needed by the body to absorb vitamin B12. Normally, Intrinsic Factor combines with vitamin B12 and it helps in the absorption of B12 through the intestines. Pernicious anemia is a rare occurrence in patients who undergo gastrectomy compared to iron deficiency anemia