Laboratory and morphological diagnostics
A wide range of laboratory tests is used to clarify the diagnosis and comprehensively assess the condition of organs. A crucial stage is the clinical and biochemical blood test. It determines formed element counts, hemoglobin levels, erythrocyte sedimentation rate (ESR), and the hematocrit value (the ratio of plasma to blood cells). The physician also evaluates the blood coagulation and anticoagulation systems, as well as the circulating blood volume (CBV) along with its components—globular volume and plasma. Blood biochemistry includes the analysis of total protein, protein fractions, glucose, enzymes, bilirubin, urea, and creatinine.
Urinalysis aims to assess specific gravity, color, and reaction (pH). Particular attention is paid to identifying pathological impurities: sugar, protein, casts, and various cellular elements.
To study cellular immunity factors, immunological tests are performed. They record the total lymphocyte count (including T- and B-cell populations), levels of complement, lysozyme, and specific immunoglobulins (IgA, IgM, IgG).
Microbiological examinations use pus, exudate, sputum, blood, or urine as specimens. The main objectives for the microbiologist are to isolate microorganisms, identify the specific pathogen, study its pathogenic properties, and compile an antibiogram (assess the susceptibility of the flora to antimicrobial drugs).
A special place is occupied by cytological and histological methods, which are critically important for the verification of oncological diseases. Materials used for microscopic examination include punctates, smears from the surface of a tumor node, fluid sediment from the abdominal or pleural cavities, and tissue pieces obtained during endoscopy or open surgery.
Functional and endoscopic examinations
Functional examinations are used to accurately assess the body's physiological status. The main methods include electrocardiography (ECG), electroencephalography (EEG), spirometry, and oscillography.
Endoscopic methods provide a vast amount of visual information regarding the condition of the internal surfaces of organs. This is achieved through the use of flexible fibroendoscopes. Depending on the area examined, the following types of procedures are distinguished:
- Bronchoscopy — examination of the bronchial tree.
- Gastroscopy — visualization of the gastric cavity.
- Colonoscopy — examination of the large intestine.
- Laparoscopy — examination of the abdominal cavity.
- Thoracoscopy — examination of the pleural cavity.
- Mediastinoscopy — inspection of the mediastinum.
- Cystoscopy — examination of the urinary bladder mucosa.
Radiological and hardware imaging methods
An important place in the examination of surgical patients is assigned to radiological methods. These include classical fluoroscopy and radiography, tomography, as well as contrast-enhanced methods: angiography for blood vessels, lymphography for the lymphatic system, and fistulography for studying fistulous tracts.
Ultrasound methods (including Doppler ultrasound) possess wide diagnostic capabilities. They allow for the detection of inflammatory infiltrates, assessment of the condition of excretory ducts, and identification of calculi (stones) in the kidneys and gallbladder. In addition, ultrasound effectively detects mass lesions (tumors, abscesses, cysts) in internal organs and makes it possible to diagnose intracranial hematomas.
Radioisotope methods are based on the principle of selective uptake by an organ of substances labeled with a radioactive marker (isotopes of strontium, phosphorus, iodine, and technetium are used). Due to their short half-life, they do not exert a harmful effect on the body. A specialized detector records the distribution of the radiopharmaceutical and generates an image of its accumulation.
Computed tomography (CT) creates a detailed image of internal organs, the brain, and bones based on the degree of X-ray absorption by tissues. CT clearly determines the localization and activity of the pathological process (stones, cysts, tumors, areas of destruction, infiltrates, abscesses), which helps the surgeon choose the most rational surgical approach.
Magnetic resonance imaging (MRI) works by registering the resonance magnetic radiation of an organ under the influence of a powerful electromagnetic field, followed by computer data processing. MRI allows for the visualization of structures in sagittal and transverse slices, determining the topography, shape, and exact dimensions of organs, as well as identifying abscesses, cysts, and tumors.
Briefly: answers to topical questions
What types of biopsy exist for obtaining tissues for histological examination?
- Fine-needle aspiration biopsy (FNAB) — performed under the guidance of radiological imaging methods.
- Core needle biopsy.
- Intraoperative biopsy — including lymph node, pleural, and lung biopsy.
- Vapor-assisted / Video-assisted thoracoscopic biopsy — obtaining samples of mediastinal lymph nodes, lung, and pleura.
- Open biopsy — diagnostic thoracotomy, justified in cases of total obliteration of the pleural cavity.
What endoscopic methods are used to examine various parts of the gastrointestinal tract?
- Gastroscopy — endoscopic examination of the stomach.
- Colonoscopy — endoscopic examination of the intestine.
- Esophagogastroduodenoscopy — endoscopic examination of the gastrointestinal tract.
- Sigmoidoscopy — endoscopic examination performed according to indications.
- Video capsule endoscopy — a method of examining the gastrointestinal tract using a wireless capsule.
Which radiopaque agents are used during angiography and fistulography?
- During angiography, a radiopaque agent is administered selectively into a blood vessel.
- During fistulography, a liquid contrast agent is injected through a thin catheter into the fistulous tract.
- The sources do not specify the exact composition of the contrast agent for these methods, nor do they provide a list of trade names.
What are the contraindications for magnetic resonance imaging (MRI)?
- MRI-incompatible implanted devices — an absolute contraindication.
- Metallic structures or elements on cerebral blood vessels.
- Metal in the orbits.
- Ferromagnetic stents and pacemakers may preclude MRI; the feasibility of the examination depends on the device specifications.
- When using gadolinium-based contrast agents, severe renal impairment—specifically a GFR of less than 30 mL/min/1.73 m²—requires special evaluation; linear agents are absolutely contraindicated in cases of renal impairment.
To remember the orientation of endoscopic examinations, rely on word roots: gastro- (stomach), colono- (intestine), thoraco- (chest/pleura), laparo- (abdomen), cysto- (bladder).
Class and exam questions
What is the difference between the operating principles of CT and MRI?
Computed tomography (CT) builds an image based on the degree of X-ray absorption by tissues. Magnetic resonance imaging (MRI) records the resonant magnetic emission of tissues located in a strong electromagnetic field.
Are radioisotope examination methods dangerous for the patient?
No, these methods are safe. The isotopes used have a very short half-life, so they do not exert any harmful or toxic effects on the patient's body.
What biological material is needed for histology and cytology?
Tissue pieces (biopsies during surgeries and endoscopies), punctates, smears from tumor surfaces, and fluid sediment obtained from the abdominal or pleural cavities are used for analysis.
What else to study on this topic
- Assessment of circulating blood volume: globular volume and plasma
- Interpretation of cellular immunity parameters and immunoglobulins
- Principles of compiling an antibiogram in microbiology
- Choosing a rational surgical approach based on CT data
- Technique of fistulography and contrast enhancement of fistulae
Master the entire topic in the "General Surgery" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Special diagnostic methods in surgery" and 3,335 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 70 video lessons on the subject
Other Topics in «CHAPTER 9. EXAMINATION OF THE SURGICAL PATIENT»
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.