Pancreatectomy - Significance and Test Procedures

What Are Pancreas?

It is an abdominal organ with both exocrine and endocrine functions. The endocrine portion of the gland accounts for 1 % to 2 % of its functions and is responsible for maintaining the glucose levels in the body; it secretes insulin, glucagon, somatostatin, ghrelin, and pancreatic polypeptide, which are released directly into the bloodstream to maintain the blood sugar levels.

The exocrine part of the pancreas secretes enzymes that are involved in digestion; it secretes amylases, lipases, and proteinases that are drained into the small intestine through the pancreatic duct. On average, the pancreas drains 1 liter to 2 liters of exocrine fluid per day; this is key because while planning a pancreatic surgery, the physiological functions of the pancreas should remain the same.

Why Is a Pancreatectomy Done?

Pancreatectomy is the surgical removal of part or all of the pancreas because of underlying pathology. The pancreas is a hand-shaped organ that is divided into five parts- head, uncinate process, neck, body, and tail. The amount of pancreas to be removed depends on the chronology and the type of the disease.

Below are mentioned the type of pancreatectomy and its associated pathology-

• Total Pancreatectomy- When the entire pancreas is removed; it is known as total pancreatectomy; it is done if there is;

1. Malignant tumors in the head of the pancreas.

2. Failure to achieve tumor-free R0 resections in the pancreatic margin.

3. Recurring pancreatic cancer.

4. If the pancreas is bleeding after the Whipple procedure (it is a complex procedure done to remove the head of the pancreas, duodenum, gallbladder, and bile duct).

5. Multifocal intraductal papillary mucinous neoplasm (IPMN) of the pancreas. It is a type of cystic neoplasm involving the pancreatic duct and its main branches.

6. Failure to achieve pancreatic anastomosis after pancreaticoduodenectomy. Pancreatic anastomosis is a surgical connection done in patients with a narrow pancreatic duct and soft pancreatic tissue.

7. Multifocal neuroendocrine tumors of the pancreas. These are tumors that start in the small intestine and then metastasize to the pancreas.

8. Hereditary pancreatic cancer.

9. Chronic pancreatitis and recurrent acute pancreatitis.

• Distal Pancreatectomy- The body and the tail of the pancreas is removed in distal pancreatectomy; it is done in-

1. Benign or malignant lesions in the body and tail of the pancreas.

2. Chronic pancreatitis in the body and tail.

3. Pseudocyst (not an actual cyst because the wall of the sac is not composed of the specific lining of cells that are characteristic of a cyst) in the body.

4. Pancreatic trauma.

5. Fistula in the pancreas.

6. Pancreatic duct disruption.

• Central Pancreatectomy- The middle portion of the neck of the pancreas is resected in central pancreatectomy; it preserves the endocrine and the exocrine function. The specific pathologies where central pancreatectomy is done are-

1. Benign and borderline lesions involving the neck of the pancreas.

2. Failure to enucleate (surgically removing a lesion intact from its surrounding capsule) a lesion.

3. Trauma to the neck and proximal parts of the pancreas.

4. To conserve the pancreas in patients who will need more than 5 cm of the distal pancreatic tail.

What Are the Contraindications of Pancreatectomy?

Surgery is only preferred in patients in whom the conservative medical treatment is non-responsive. However, in a few patients, surgery is not a viable option due to the presence of associated comorbidities. The contraindications depend on the type of pancreatectomy performed rather than the underlying comorbidity; they are-

Absolute Contraindication to Open and Laparoscopic Pancreatectomy: Surgically removing the pancreas is an absolute no-no for these patients; the conditions that fall under this category are-

• Patients with underlying bleeding disorders.

• Poor functional status where the patient is unable to perform basic daily activities.

• Medical comorbidities like uncontrollable diabetes and hypertension.

Laparoscopic Technique- It is a well-tolerated approach but can be difficult to perform in patients who are-

• Extremely obese.

• In patients who have had abdominal surgeries.

• Advanced stages of pancreatic cancer.

• When blood vessels are involved in a pancreatic tumor.

• Who are intolerable to pneumoperitoneum (presence of air or gas in the abdominal cavity).

Total Pancreatectomy- This approach is not advised for lesions that can be removed whilst sparing the pancreatic tissue.

• Distal Pancreatectomy- Contraindicated in pancreatic lesions that are unable to achieve an R0 resection.
• Central Pancreatectomy- It is contraindicated when all of the malignant components- the vessels, lymph nodes, and mesentery cannot be completely removed.

What Tests Are Done Before Pancreatectomy?

Patients undergoing pancreatic resection have to undergo the following investigations-

• Preoperative Ca19-9 Check- This test measures the amount of Ca19-9 protein in the blood. Increasing levels of this protein are seen in malignancies and disseminated diseases, and it can also be used as a reference point for post-operative monitoring.

• Computed Tomographic (CT) Scan- A CT scan will provide the exact location and size of the lesion along with the extent of the lesion's involvement in the surrounding tissues.

• Endoscopic Ultrasound- Helps to identify vascular invasions and the resectability of the lesion.

• Magnetic Resonance Imaging- It is the tool of choice to identify abnormalities in the pancreatic and biliary ducts.

• Positron Emission Tomographic (PET) Scan- Useful in confirming post-operative lesions with Ca19-9 assistance.

How Is a Pancreatectomy Done?

Ideally, conservative medical therapy is the first line of treatment for problems related to the pancreas; if this fails, surgery is the next available treatment modality. A strict preoperative evaluation is done before the procedure to avoid any post-op complications. The patient's medical history, physical examination, current medical conditions, past surgical procedures, current signs and symptoms, and past family history of cancer are important in planning the surgery.

The surgeon will choose either an open or laparoscopic pancreatectomy depending on the pathology, both of which are discussed below-

Open Technique- This technique is done under general anesthesia, so the patient is asleep and unaware of the procedure.

• The surgeon makes a midline incision extending from the lower end of the sternum to the belly button.

• After gaining access to the abdomen, the underlying muscles are retracted, and the associated ligaments are ligated.

• The pancreas is a retroperitoneal organ (located behind the inner lining of the abdomen), so the surgeon will have to open the lesser sac (space posterior to the lesser omentum) to visualize the pancreas.

• The exposed pancreas is then surgically resected, followed by reconstruction. Reconstruction involves different kinds of anastomosis (the surgical connection between two structures) and gastrojejunostomy (a surgical procedure that connects part of the stomach to the jejunum).

• After confirming that all the anastomosis is intact and there is no leakage, a feeding tube, and a suction drain can be placed depending on the surgeon’s decision.

• The incision is sutured, and the patient is monitored until their vitals are stable.

Laparoscopic Technique- Instead of one single large incision, several small incisions are made in this approach. The surgeon inserts a laparoscope (a fiber-optic instrument with a camera) that transmits video to a monitor in the operating room. After direct visualization of the underlying anatomy, the surgeon inserts special instruments to resect the pancreas.

What Are the Complications of Pancreatectomy?

Pancreatectomy is a serious surgical procedure with some of the most feared complications; they are-

• Post-operative fistulas heal without intervention but will occasionally need a percutaneous drain to clear out the small fluid collection.

• Post-operative diabetes development is seen in almost ten percent of the patients who underwent pancreatectomy, and this type of diabetes is known as pancreatogenic diabetes.

• Total pancreatectomy can also cause liver steatosis, steatorrhea, retinopathy, and neuropathy and predispose the patient to cardiovascular diseases.

• Splenic infarction and gastric varices formation can occur after the procedure.

• Delayed gastric emptying and small bowel obstruction are seen in almost 50 % of the patients.

• Intra-abdominal hemorrhage and anastomosis leak are possible regardless of the technique.

• Bleeding, infection, and wound complications which are common in most surgeries, are also seen in pancreatectomy.

An interprofessional team consisting of a surgeon, an anesthesiologist, nurses, and intensive care unit (ICU) personnel is essential to manage the patient undergoing pancreatectomy. A meticulous technique and efficient post-operative care will reduce the development of complications.

Conclusion:

Pancreatectomy is a serious procedure that is only performed when the benefits outweigh the risks. The patient and related family members should be counseled regarding the realistic expectations of the procedure. With the advancement in minimally invasive techniques in recent years, patients are able to experience less pain, reduced hospital stay, and overall better outcomes from the procedure.