Chronic pancreatitis - Diagnosis

Diagnosis of chronic pancreatitis presents significant difficulties due to the anatomical location of the pancreas, its close functional connection with other organs of the gastrointestinal tract, and the lack of simple and reliable research methods.

The method of coprological examination has not lost its significance, especially if it is carried out repeatedly (3-4-5 times or more with short intervals) - in this case the results of the study become more reliable. Based on the results of coprological examination, it is possible to judge the state of the digestive process, which largely depends on the function of the pancreas. In pancreatogenic digestive disorders, the digestion of fats is most impaired (since it occurs exclusively due to pancreatic lipase), therefore in these cases, coprological examination primarily reveals steatorrhea, and to a lesser extent, creato- and amylorrhea.

Methods for determining pancreatic enzymes in blood serum and urine have become widely used in practical medicine for diagnosing pancreatic diseases.

The main advantages of these methods are their relative simplicity and labor-intensiveness.

Pancreatic enzymes enter the bloodstream in several ways: firstly, from the secretory ducts and ducts of the gland, secondly, from the acinar cells into the interstitial fluid and from there into the lymph and blood (the so-called enzyme evasion phenomenon), thirdly, the absorption of enzymes occurs in the proximal parts of the small intestine.

An increase in the level of enzymes in the blood and urine occurs when there is an obstruction to the outflow of pancreatic secretion and an increase in pressure in the pancreatic ducts, leading to the death of secretory cells. A sign of exacerbation of chronic pancreatitis can only be a significant increase in the activity of amylase in the urine - tens of times, since a slight or moderate increase in this indicator is also found in other acute diseases of the abdominal organs. Many authors attach greater importance to the determination of enzymes in the blood serum, more often a study of the level of amylase is carried out, less often - trypsin, trypsin inhibitor and lipase.

It should be borne in mind that the amylase content in urine depends on the state of kidney function, therefore, in doubtful cases, with impaired kidney function and signs of exacerbation of chronic pancreatitis, the so-called amylase-creatine clearance (or coefficient) is determined.

Of great importance in assessing the condition of the pancreas in chronic pancreatitis is the study of the exocrine function, the degree and nature of the disorder of which can be used to assess the severity of the disease.

To date, the most common method remains duodenal sounding using various stimulants of pancreatic secretion: secretin, pancreozymin or cerulein (tacus). In chronic pancreatitis, a decrease in bicarbonates and all enzymes is noted, especially in severe forms.

To study the endocrine function of the pancreas with normal fasting blood glucose levels, a glucose tolerance test is used. With elevated fasting blood glucose levels, a study of the so-called sugar profile is performed.

X-ray methods are widely used in the diagnosis of pancreatitis. Sometimes, even on plain images of the abdominal cavity, it is possible to detect usually small areas of calcification in the pancreas (calcified areas of former necrosis zones, stones in the ducts of the gland).

Duodenography under conditions of artificial hypotension of the duodenum, which allows to detect an enlargement of the head of the pancreas and changes in the BSD, has not lost its diagnostic value to this day.

Characteristic signs of the X-ray picture of damage to the head of the pancreas during duodenography:

• increase in the unfolding of the duodenal loop,
• an indentation on the inner wall of its descending part,
• Frostberg's sign - deformation of the internal contour of the descending part of the duodenum in the form of a mirror image of the number 3,
• double contour of the inner wall (“culio symptom”) and jaggedness of the inner contour of the duodenum.

Unlike pancreatitis, a tumor of the head of the pancreas reveals an indentation on a limited area of the internal contour of the duodenum, rigidity and ulceration of its wall.

For a more detailed study of the BSD area, the terminal section of the common bile duct and the state of the pancreatic ducts, ERCP is used. The method is technically complex and not safe: in 1-2% of cases it gives severe complications, so it should be used only for serious indications (differential diagnostics between a tumor, etc.), but it is of great importance, especially when differential diagnostics of chronic pancreatitis and pancreatic cancer is necessary. There is information in the literature that ERCP gives reliable information in chronic pancreatitis in 94% of cases, in stenosis of the BSD - in 75-88.8%, malignant lesions - in 90%.

According to the pancreatogram, the signs of chronic pancreatitis include deformation of the contours of the main duct, unevenness of its lumen with areas of stenosis and dilation (bead-shaped), changes in the lateral ducts, blockage of small ducts (first and second order) with the formation of cystic dilatations, heterogeneity of contrasting of the gland segments, and impaired emptying of the main duct (accelerated - less than 2 minutes, slow - more than 5 minutes).

The contrast agent is injected into the pancreatic ducts using a duodenofibroscope through a cannula in an amount of 3-6 ml. Injection of a larger volume should be avoided, as this increases intraductal pressure, which in turn can cause an exacerbation of pancreatitis, up to the development of necrosis.

In diagnostically complex cases, selective angiography is indicated. Despite its significant information content, this method has very limited clinical application due to the complexity of the study, mainly for differential diagnostics with a neoplastic process and in severe, painful forms of chronic pancreatitis. Currently, a number of basic angiographic signs of chronic pancreatitis have been identified: uneven narrowing of the lumen of arteries and veins, rupture of arteries; displacement of arteries and veins, occurring due to an increase in the size of the gland and the adhesive process that occurs in the surrounding tissues; strengthening or weakening of the vascular pattern of the pancreas; accumulation of contrast agent in the pancreas; enlargement of part or the entire organ. In case of pancreatic cysts, angiograms reveal an area completely devoid of vessels.

CT is of great importance in the diagnosis and differential diagnosis of pancreatitis. With its help, tumor and inflammatory processes in the pancreas are recognized with an accuracy of up to 85%. In chronic pancreatitis, the sensitivity of CT is 74%.

In recent years, ultrasound of the pancreas has been widely used in clinical practice. It should be emphasized that this is one of the few methods that is not labor-intensive and not burdensome for the patient. The diagnosis of chronic pancreatitis established on the basis of ultrasound coincides with the final clinical diagnosis in 60-85% of cases.

The main ultrasound signs of pancreatic pathology are changes in structure, with echo signals being of low (due to parenchymal edema) or increased (due to fibrous restructuring of the parenchyma) intensity; changes in size (limited or diffuse); changes in contour, which can be blurred (due to inflammation, edema), uneven, jagged (with chronic inflammation, tumor), or outlined (with a cyst, abscess, tumor).

Instrumental methods of examination are of great importance in determining the nature and extent of damage to the pancreas. Each of them has its own diagnostic capabilities and provides certain information. Therefore, examination of the patient should be based on the complex application of these methods.

Diagnostics should begin with simple and unburdensome examinations for the patient, such as ultrasound, duodenography under artificial hypotension. It should be taken into account that ultrasound and CT provide almost identical information. With clear ultrasound visualization of the pancreas, CT is inappropriate. In unclear cases, with suspected volumetric lesion of the BSD and the terminal section of the common bile duct, ERCP and selective angiography must be included in the examination plan.

Laboratory examination

Mandatory examination methods

• Complete blood count: increased ESR, leukocytosis with a shift to the left during exacerbation.
• General urine analysis: presence of bilirubin, absence of urobilin in the pseudotumor (icteric) variant; increase in a-amylase during exacerbation, decrease in the sclerosing form with impaired exocrine function (normal 28-160 mg/dl).
• Biochemical blood test: in case of exacerbation - increased content of a-amylase (normal 16-30 g/hcl), lipase (normal 22-193 U/l), trypsin (normal 10-60 μg/l), y-globulins, sialic acids, seromucoid, bilirubin due to the conjugated fraction in the icteric form; glucose in case of endocrine function disorder (sclerosing form); decreased albumin level in case of prolonged course of the sclerosing form.
• Study of the exocrine function of the pancreas:

Determination of enzymes (lipase, a-amylase, trypsin), bicarbonate alkalinity in the duodenal contents before and after the introduction of 30 ml of 0.5% hydrochloric acid solution into the duodenum: collect 6 portions every 10 minutes, normally after the introduction of hydrochloric acid in the first two portions of juice the enzyme concentration decreases, from the 3-4 portion it increases, in the 6th it reaches the initial level or even exceeds it. In chronic pancreatitis with exocrine insufficiency, a marked decrease in enzymes and bicarbonate alkalinity is noted in all portions. The test is performed using a two-channel gastroduodenal tube with separate aspiration of the gastric and duodenal contents;

Lasus test: urine test for hyperaminoaciduria. In exocrine pancreatic insufficiency, the physiological ratio of amino acids absorbed in the small intestine, which is necessary for their utilization in the liver, is disrupted; as a result, amino acids are not absorbed and are excreted in increased quantities in the urine. The test is performed as follows: 30 ml of 2% zinc sulfate solution is added to 30 ml of urine and after 24 hours, microscopy of the urine reveals polymorphic crystals of a black-gray-purple or yellowish color in the urinary sediment;

Glycoamylase test: determination of the level of alpha-amylase in the blood before and 3 hours after a 50 g glucose load. An increase in the concentration of alpha-amylase in the blood by more than 25% indicates pancreatic pathology;

Prozerin test: determination of the content of alpha-amylase in urine (the norm is 28-160 g / h l) before the introduction of 1 ml of 0.06% prozerin solution and every 0.5 hour for two hours after the introduction. The level of alpha-amylase in urine after the introduction of prozerin increases by 1.6-1.8 times and returns to the original after 2 hours. In mild and moderate chronic pancreatitis, the initial level of alpha-amylase is normal, after the introduction of prozerin it increases more than 2 times and does not return to normal after 2 hours. In case of exacerbation of the recurrent form, the initial concentration of alpha-amylase is above normal, after the introduction of prozerin it increases even more and does not return to normal after 2 hours. In the sclerosing form, the initial level of alpha-amylase is below normal and does not increase after stimulation.

Secretin-pancreozymin test: determination of bicarbonate alkalinity and concentration of enzymes alpha-amylase, lipase and trypsin in basal duodenal contents, and then after intravenous administration sequentially of secretin at a dose of 1.5 U/kg of body weight (it stimulates secretion of liquid part of pancreatic juice rich in bicarbonate; after administration, duodenal contents are extracted within 30 min); and pancreozymin at a dose of 1.5 U/kg of body weight (it stimulates secretion of pancreatic enzymes) and duodenal contents are obtained within 20 min. After administration of secretin, the amount of bicarbonates increases normally compared to basal by 10-11 times, the amount of enzymes in 20 min (flow rate) increases after administration of pancreozymin as follows: alpha-amylase by 6-9 times, lipase by 4-5 times, trypsin by 7-8 times. In the initial phase of chronic pancreatitis, there is an increase in indicators (hypersecretory type), and later, as a rule, a decrease (hyposecretory type).

• Study of the endocrine function of the pancreas - glucose tolerance test: tolerance is reduced in the long-term course of the disease, especially in the sclerosing variant.
• Coprocytothramma: ointment-like consistency, undigested fiber, creatorrhea, steatorrhea, amylorrhea with severe exocrine insufficiency.

Some doctors suggest using the iodolipol test as a screening test for chronic pancreatitis . It is based on the ability of lipase to break down iodolipol, resulting in the release of iodide, which is excreted in the urine. The test is carried out as follows. The patient urinates at 6 am, then takes 5 ml of a 30% iodolipol solution orally, washing it down with 100 ml of water. Then collect 4 portions of urine: after 1, 1.5, 2 and 2.5 hours. From each portion, take 5 ml of urine, oxidize it with 1 ml of a 10% sulfuric acid solution, add 1 ml of a 2% sodium nitrate solution and chloroform, shake thoroughly. The intensity and speed of the appearance of the red color (free iodine) in chloroform serve as indicators of lipase activity, marked semi-quantitatively by 1-4 pluses. With normal pancreatic lipase activity, the following results are observed: 1 portion + or ±; 2 portion ++ or +; 3 portion +++ or ++; 4 portion ++++ or +++.

Insufficient lipase activity and, consequently, insufficient pancreatic function is manifested by a significant decrease in staining intensity.

• Pancreozymin test.In healthy people, when the exocrine function of the pancreas is stimulated, the level of pancreatic enzymes in the blood serum does not exceed the upper limit of the norm. In case of pancreatic pathology, conditions are created for excessive penetration of enzymes into the blood, therefore, increased activity and formation of a large number of enzymes cause an increase in the level of fermentemia. This is the basis of the serum pancreozymin test. In the morning on an empty stomach, 10 ml of blood is taken from the patient's vein, pancreozymin is administered through the same needle at a rate of 2 U per 1 kg of body weight at a concentration of 5 U in 1 ml. The rate of administration of the drug is 20 ml in 5 minutes. After pancreozymin, secretin is immediately administered at a rate of 2 U per 1 kg of body weight at the same rate. 1 and 2 hours after stimulation, 10 ml of blood is taken from the patient's vein. Trypsin, its inhibitor, lipase, and amylase are determined in the three portions of blood obtained.

An increase in the enzyme level by 40% compared to the baseline is considered a positive test result.

Instrumental data

Ultrasound examination of the pancreas. Characteristic signs of chronic pancreatitis are:

• heterogeneity of the structure of the pancreas with areas of increased echogenicity;
• calcification of the gland and pancreatic duct stones;
• unevenly dilated duct of Wirsung;
• enlargement and compaction of the head of the pancreas in the pseudotumor form of the disease;
• uneven contour of the pancreas;
• increase/decrease in size of the pancreas;
• diffuse increase in echogenicity of the pancreas;
• limited displacement of the gland during breathing, its rigidity during palpation;
• pain during echoscopically controlled palpation in the area of the gland projection;
• absence of changes in ultrasound of the pancreas in the early stages of chronic pancreatitis.

X-ray examination(duodenography in conditions of hypotension) allows us to detect the following characteristic signs:

• calcification of the pancreas on plain radiograph (a sign of chronic calcifying pancreatitis);
• unfolding of the arch of the duodenum or its stenosis (due to an increase in the head of the pancreas);
• indentation on the inner wall of the descending part of the duodenum; Frostberg's sign - deformation of the inner contour of the descending part of the duodenum in the form of a mirror image of the number 3; double contour of the posterior wall ("whisker symptom"), jaggedness of the inner contour of the duodenum;
• enlargement of the retrogastric space (indicates an increase in the size of the body of the pancreas);
• reflux of contrast into the pancreatic duct (duodenography under compression).

Endoscopic retrograde cholangiopancreatographyreveals the following signs of chronic pancreatitis:

• uneven expansion of the Wirsung duct, its broken nature, deformation of the contour;
• pancreatic duct stones;
• heterogeneity of contrasting of gland segments;
• disturbance of emptying of the main pancreatic duct.

Computed tomography and magnetic resonance imaging of the pancreasreveal a decrease or increase in size, changes in the density of the gland, calcifications, pseudocysts.

Radioisotope scanning of the pancreasusing methionine labeled with selenium-75 - characterized by an increase or decrease in its size, diffuse uneven accumulation of the isotope.

Differential diagnosis of chronic pancreatitis

Peptic ulcer disease: characteristic anamnesis, pain associated with food intake, seasonality of exacerbations, absence of diarrhea.

Gallstone disease and cholecystitis: characterized by pain in the right hypochondrium with irradiation to the right and upwards, to the back, under the right shoulder blade, tenderness on palpation in the right hypochondrium, Kerr's, Ortner's, Murphy's symptoms. Ultrasound and cholecystography are performed to detect stones.

Inflammatory diseases of the small and large intestines: characterized by the absence of pronounced disorders of the exo- and endocrine functions of the pancreas. For differential diagnosis, X-ray, endoscopic examination of the large and, if indicated, small intestine, bacteriological examination of feces are used.

Abdominal ischemic syndrome: systolic murmur in the epigastric region and changes or obstruction of the celiac trunk or superior mesenteric artery according to aortograms.

Pancreatic cancer: characteristic changes are observed during ultrasound, selective angiography, CT, laparoscopy with biopsy.

Indications for consultation with other specialists

• Surgeon: if surgical treatment is necessary.
• Oncologist: when pancreatic cancer is detected.
• Endocrinologist: in the development of endocrine insufficiency and diabetes mellitus.

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