Pancreas Clinical Features, Principles Of Investigation

Surgical Anatomy Of The Pancreas

The pancreas is both endocrine and exocrine organ situated retroperitoneally behind the stomach. It is a soft and fleshy gland (pancreas—all flesh), extending from the duodenum on the right side to the spleen on the left side, the entire length being 6 inches. It weighs approximately 80 g.

Surgical Anatomy Of The Pancreas Parts

• The head lies within the C-loop of duodenum. The uncinate process projects from the left inferior portion of the head over which course the superior mesenteric vessels.
• There are 5-6 small thin veins connecting this portion of the head with superior mesenteric veins. These veins have to be carefully divided during pancreaticoduodenectomy.
• Superior mesenteric vein continues above as portal vein after joining the splenic vein. During pancreaticoduodenectomy for peri¬ampullary carcinoma, infiltration into the portal vein should be ruled out before any major structure is divided. This is done by inserting a finger between the portal vein and head of pancreas, both from above and below.
• The neck is about 2 cm and is related posteriorly to superior mesenteric vessels.
• Body and tail: The head and neck continue as body which is placed transversely. It slopes upwards across the aorta and ends as tail of the pancreas, which is enclosed within lienorenal ligament along with splenic vessels. A large cystadenoma arising from the tail of the pancreas can move with respiration because of its contact with the spleen.

Blood Supply Of The Pancreas

• Arterial Supply
  • Splenic artery is the chief artery supplying the neck, body and the tail. Arteria pancreatica magna refers to one large branch of splenic artery.
  • Superior and inferior pancreaticoduodenal arteries supply not only head of pancreas but also the adjacent duodenum. Thus, during any surgery which involves excision of the head, the C-loop of the duodenum is also removed. Thus, pancreaticoduodenectomy becomes a major surgery.
• Venous Drainage
  • Body, neck and tail drain into splenic vein by means of multiple small veins.
  • The head is drained by superior pancreaticoduodenal vein which drains into portal vein and inferior pancreaticoduodenal vein drains into superior mesenteric vein.
• Islets of Langerhans (Endocrine)
  • 75% : β cells
  • 20% : α cells
  • 4% : δ cells
• Pancreatic Duct
  • The main pancreatic duct (duct of Wirsung), a tubular structure, drains entire pancreas from tail to the head. It joins the common bile duct and forms ampulla of Vater. This ampulla opens on the duodenal papilla (a nipple-like elevation) in the 2nd part of the duodenum. Normal diameter of pancreatic duct is 2-3 mm. When it is dilated more than 6-8 mm, as in chronic pancreatitis, longitudinal pancreatico- jejunostomy can be done.
  • Accessory pancreatic duct of Santorini drains the uncinate process and lower portion of the head and opens into the duodenum 2 cm above the opening of the main duct. The two ducts communicate with each other at many sites.
  • The main pancreatic duct is lined by columnar epithelium which becomes cuboidal in the ductules.

Pancreatic Juice

• Bicarbonate-rich, protein-rich, alkaline fluid
• 2.5 litres/day
• Rich in proteins—15 g of protein/day
• Thus acidic chyme in the duodenum is alkalinised by pancreatic juice.
• Protein is secreted by acinar cells, fluid and electrolytes by ductal cells.
• Secretions are stimulated by three phases:
  1. Cephalic phase is mediated by acetylcholine—10% of secretion
  2. Gastric phase—mediated by gastrin and vagus— 15%
  3. Intestinal phase—75% release mediated by release of secretion from duodenal acidification and stimulated release of bile into 2nd part of duodenum following entry of fat and proteins.

 

Courvoisier’s Law

Courvoisier’s Law: In a jaundiced patient, if the gallbladder is palpably enlarged, it is not due to stones. In case of stones, previous inflammation would have made gallbladder fibrotic and hence, will not be palpable. From clinical point of view, 90% of cases of obstruc-tive jaundice are due to stones, periampullary carcinoma or carcinoma of the head of pancreas.

Clinical Features of Gallbladder Mass

• Egg-shaped mass/pyriform shape
• Moves with respiration
• Tensely cystic, feels firm (Murphy’s point), located in the right hypochondrium
• Superficially placed
• Intra-abdominal, intraperitoneal
• Chronic pancreatitis

Exceptions to Courvoisier’s Law

1. Double impaction: One stone in the CBD and one stone in the cystic duct. Gallbladder may be palpable in such cases.
2. Periampullary carcinoma in a patient who has undergone cholecystectomy.
3. Primary oriental cholangiohepatitis causing stones in the CBD (gallbladder is normal in these cases). These stones are called primary CBD stones.

Choledocholithiasis

Types of CBD Stones

1. Primary stones: These stones are formed in the CBD or within intrahepatic ducts. They are multiple, pigment stones or often mixed stones. Various causes are:
   • Infections of biliary tree and infestation— parasites such as clonorchiasis.
   • Congenital—Caroli’s disease or choledochal cyst.
   • Biliary dyskinesia—defective pathophysiology of biliary tree.
   • Other causes—diabetes, malnutrition.
2. Secondary stones: These stones originate from gallbladder and stay in CBD—usually supra-duodenal portion—then get enlarged to attain large size over a period of time. These stones can give rise to cholangitis.

Natural History of CBD Stones

• Symptom
  •  Asymptomatic
  • Cholangitis — 20%
  • Jaundice — 20%
  • Biliary colic — 15%
  • Pancreatitis
• % of patients
  • 40%
  • 20%
  • 20%
  • 15%
  • 5%

Cholangitis: Bacterial infection of bile duct is called cholangitis.

• Cholangitis Predominant Organisms
  • E. coli, Klebsiella, Pseudomonas, enterococci, Proteus.
  • Bacteroides and other anaerobes (Clostridium perfringens)
• Cholangitis Symptoms and Signs
  • Biliary colic, jaundice and chills and rigors are called Charcot’s triad.
  • Tenderness may be present in the upper abdomen.
• Cholangitis Investigations
  • Leukocytosis, high bilirubin levels and alkaline phosphatase levels are diagnostic tests.
  • Ultrasound, CT scans, ERCP are indicated to confirm/rule out the various causes.
• Cholangitis Treatment
  • Intravenous antibiotics
  • Emergency endoscopic sphincterotomy, extraction of stones in choledocholithiasis, endoscopic stoning in cases of stenosis or stricture.
  • Percutaneous transhepatic biliary drainage (PTBD) in high obstructions.
  • Laparotomy—drainage of CBD—T-tube insertion.

Reynolds’ Pentad of Acute Obstructive Cholangitis: A few cases of CBD stones present with serious problems of cholangitis described as Reynold’s pentad

1. Persistent pain
2. Fever
3. Persistent jaundice
4. Shock
5. Altered mental status

Treatment Of Periampullary Carcinoma

Surgical Treatment

1. Radical pancreaticoduodenectomy—’Whipple’s operation’.: In this operation, the growth along with ‘C’ loop of duodenum up to DJ flexure, proximal jejunum, head of the pancreas up to the neck are removed and partial gastrectomy is done. This is followed by:

• Lower CBD and gallbladder is also removed.
• Pancreaticojejunal anastomosis (PJ), gastro-jejunostomy (GJ) and choledochojejunostomy (CJ).
• This is a major operation and carries 5-10% mortality due to pancreatic leakage or biliary leakage.
• Whipple’s operation is indicated in cases of mobile growth with no metastasis and where the general condition of the patients is good.
• Patients with cholangitis are treated with pre-operative CBD stent followed 3-4 weeks later by Whipple’s procedure.

2. Pylorus-preserving pancreaticoduodenectomy (PPPD) or Traverso-Longmire procedure: In this operation, pylorus is preserved. Thus, gastric motility is not disturbed.

3. Triple bypass: Cholecystojejunostomy + enterostomy + gastrojejunostomy: This is a palliative surgery in which distended gall-bladder is anastomosed to a long loop of jejunum  (40 cm) to relieve jaundice. To prevent food particles entering into the gallbladder, enteroenterostomy is done. Cholecystojejunostomy is easy to do compared to choledochojejunostomy.

• Most of the patients develop duodenal obstruction caused by the growth in the postoperative period. Hence, a palliative GJ is done at the same time.
• In the absence of duodenal obstruction, if surgeon thinks that patient may live longer, beyond 6 months, GJ is indicated (for a possible duodenal obstruction occurring later).

Nonsurgical Treatment: Very elderly patients (age criteria not clear) who are not fit candidates for surgery and patients who have metastasis can be treated by palliative stenting. However, results of a surgical bypass is superior to stenting. Also, the stent needs to be changed frequently. Classify biliary strictures. Enumerate the causes, clinical features, investigations and management of biliary strictures.

Stricture Of The CBD

80% of strictures occur following surgery on the biliary tree. They are called postoperative strictures. 20% are due to inflammatory pathology. It gives rise to slowly progressive, painless jaundice. Strictures account for 1-2% cases of obstructive jaundice.

Classification of bile duct injuries following laparoscopic cholecystectomy

1. Bismuth classification: Five types of bile duct injuries are recognosed based on the distance from the hilar structure—bile duct bifurcation, the level of injury, the involvement of bile duct bifurcation, and indivi-dual right sectoral duct.

2. Bismuth classification of postoperative stricture:

1. Type 1: Low common bile duct; stump >2 cm
2. Type 2: Middle common hepatic duct, stump <2 cm
3. Type 3: Hilar—confluence of right and left duct intact
4. Type 4: Right and left ducts separated
5. Type 5: Involvement of the intrahepatic ducts 2. Strasberg classification: It helps in differentiating small (bile leakage from the cystic duct or aberrant right sectoral branch) and serious injuries. Both these have been depicted.

Stricture Of The CBD Causes

1. Postoperative post-traumatic

• Difficult cholecystectomy: When the gallbladder is fibrosed, densely stuck to the right hepatic duct or to the common bile duct or as in early cholecystectomy due to oedema around Calot’s triangle, injury can occur to the right hepatic duct or to the CBD or CHD resulting in stricture.
• Difficult cholecystectomy, dangerous cholecystectomy and faulty dissection are the important factors for postoperative bile duct strictures.
• Dissection at fault: Ignorance of anomalies such as short cystic duct or too much traction on the gallbladder distorts CBD and predisposes to injury. It is the duty of the surgeon to show his assistants the Y junction which is formed by the cystic duct, common hepatic duct above and common bile duct below before dividing any structures in this area.

2. Post-inflammatory: Post-inflammatory strictures follow recurrent attacks of cholangitis due to:

• Stones in the CBD or CHD
• Parasites like Ascaris lumbricoides in the biliary tree or Asiatic cholangiohepatitis produced by Chinese liver fluke infestation (Clonorchis sinensis).
• Primary sclerosing cholangitis wherein the cause is not known.

3. Malignant strictures: Malignant strictures are due to cholangiocarcinoma.

Malignant strictures Clinical features

• History of cholecystectomy in the past with or without profuse discharge of bile in the postoperative period.
• A slowly progressive, painless jaundice deepening day by day.
• Hepatomegaly due to back pressure.
• Recurrent cholangitis due to stasis of bile.

Malignant strictures Investigations

• USG—to rule out residual stones in CBD, to demonstrate intrahepatic dilatation.
• ERCP or PTC may demonstrate a stricture in the CBD or CHD with proximal dilatation.
• T-tube cholangiography, if T-tube is in place.
• MRC is noninvasive and is better than PTC.

Malignant strictures Treatment

• If it is due to laparoscopic clipping without transection of the CBD, it is better to re-explore and remove the clips and a T-tube or an endoscopic stent can be placed in the CBD.
• Late cases can be managed by choledochojejuno- stomy or hepaticojejunostomy by anastomosing a loop of jejunum to the dilated portion above the stricture. However, the general condition of the patient should be improved before surgery.
• Prevention is better than treatment. Try to prevent bile duct injuries during laparoscopic cholecystectomy.

Sclerosing Cholangitis

It is characterised by development of multiple strictures and dilatation of CBD with features of fibrous thickening of CBD.

Sclerosing Cholangitis Types

1. Primary: No cause is found. However, it can be associated with conditions given in Key Box 42.13.
2. Secondary: It is due to stones or injuries.

Sclerosing Cholangitis Complications: Due to long-standing obstruction, biliary cirrhosis and cholangiocarci- noma can develop.

Sclerosing Cholangitis Diagnosis

• Ultrasound can demonstrate intrahepatic dilatation.
• MRCP is a noninvasive invest¬igation which can demonstrate: Sclerosing multiple strictures and dilatation. cholangitis
• ERCP is the investigation of choice which can demonstrate the strictures in the CBD and dilatation which is described as having a beaded appearance. However, the risk of suppurative cholangitis is present.

Sclerosing Cholangitis Treatment

• It is difficult.
• Stenting is the choice although stents may have to be replaced or changed, if blockage occurs or if infection sets in.