Other blood studies also relate to blood clotting. The bleeding time should be about 4 minutes. If it's prolonged, you may have a bleeding problem. The PT and PTT are special measures of coagulation, and all that's important is that PT should be about 1214 seconds, and PTT should be about 45 seconds. Anticoagulants, such as coumadin, will cause the PT to be elevated, and heparin will cause the PTT to be elevated. The physician must monitor these values to make sure that your blood is not too thin when you are taking these medicines.
Urinalysis is another important study and includes measurement of blood in the urine, since normally there should be none; this may indicate lab error, infection, kidney stone, or malignancy. Pus in the urine indicates a urinary tract infection. BUN (blood urea nitrogen) and creatinine (Cr) help us evaluate kidney function with normal BUN about 718 and Cr about 0.20.8.
Bilirubin is one of the breakdown products of blood and measures the ability of the liver to function properly. An elevated bilirubin may mean liver disease, but is also elevated with gall bladder disease when a gallstone is blocking the main bile duct (see chapter on Gall Bladder and Bile Ducts) or when there is leakage of bile after gall bladder surgery. Normal bilirubin is about 0.1 to 1.1, although there are certain people who have elevated bilirubin because of a strange, otherwise asymptomatic disease called Gilbert's disease. Your doctor knows all about these things. Calcium, Ca, and phosphorus (P) are important chemicals in bone strength, and Ca is important in blood clotting. The blood levels of these elements are controlled by small glands in the neck behind the thyroid gland called the parathyroid glands. There are several benign and malignant diseases of these glands which may be indicated by an elevated Ca and a lowered P. Also, since Ca is used in blood coagulation, when there has been a lot of bleeding and blood clotting, the Ca level may fall. Normal Ca is 911 and normal P is 24.
Amylase and lipase are enzymes or chemicals in the blood secreted predominately by the pancreas. Elevations of these may indicate pancreatitis (see Pancreas) or inflammation in an organ near the pancreas, such as the liver or gall bladder. Amylase normally is 25125, but may rise into the thousands with pancreatitis and, similarly, lipase, which is normally about 23208, can get as high as 20,000 in active disease.
We have already discussed blood type and crossmatching in Chapter 18. We can get blood samples and obtain specific blood products that a person needs rather than just giving “whole” blood. These products include fresh frozen plasma, platelet concentrate, cryoprecipitate, and other complex blood products that's why we have special physicians called hematologists to sort out the problem.
SGOT, normal level 540, SGPT, normal 756, and LDH, normal 100190, are substances which indicate liver disease. It is a complex subject, and all you need to know is that, when they are elevated, the physician has to determine which of many diseases are present, such as hepatitis, cirrhosis, malignancy, bile duct obstruction or a whole host of other diseases. Alkaline phosphatase, normal range 2090, may be elevated in several diseases but is important as an indicator of bile duct obstruction, either from inflammation, stones, or malignancy. Prostatic acid phosphatase is secreted by certain cells in the prostate gland, and elevation may indicate disease of the prostate, while prostate specific antigen (PSA) may indicate cancer of the prostate gland.
There are hundreds of other laboratory tests that physicians order to help in the diagnosis of disease, and not only blood is used in these tests. We can obtain spinal fluid for infections and malignancies and other diseases of the brain and spinal cord; paracentesis fluid, fluid from the abdomen, to be analyzed for infection, malignancy or chronic diseases; pleural fluid, or thoracentesis fluid from inside the chest for the same type of determinations; and, finally, fluid, aspirated from cysts anywhere in the body for diagnosis, including breast cysts, sebaceous cysts, and ganglion cysts. There are many blood studies for rare metals such as magnesium, zinc, and mercury.
The term C&S refers to culture and sensitivity, when samples are taken of possibly infected areas. The culture part means that the bacteria are grown outside the body on a special plate called a Petri dish in a nutrient called Agar. When the bacterial colonies grow, special laboratory workers can identify the organism, such as staph or strep or T.B. The bacteria is then tested for sensitivity to certain drugs, and a report is then sent to the doctor, indicating the name of the bacteria and the antibiotics that will be most effective in eradicating it.
Other laboratory tests (you have heard about and their normal levels) are: cholesterol <200, serum proteins, albumin and globulin, and blood sugar, 60100. The laboratory can also measure blood and urine levels of many drugs, such as digitalis, chemotherapeutic agents, alcohol, and street drugs. Arterial blood gases (ABG's) measure the amount of oxygen in your blood, and pulmonary function tests measure how much air you can take in your lungs and can determine lung function problems caused by smoking, infection, or other diseases.
Now you have a brief overview of diagnostic laboratory tests—I hope it hasn't been too boring and that it has given you some insight into the adjunctive measures your doctor can use in making a diagnosis.
Chapter 26
RADIOLOGY AND DIAGNOSIS FOR THE SURGEON
I won't go so far as to offer an apology
That surgeons are in bed, so to say, with radiology.
But we are quite dependent on what they can show,
And we're often enamored with that which they know.
You see, to find answers and make diagnoses,
We often need xrays, from head down to toesies.
They get complex angiograms and CT Scans rolling,
Sometimes I'm not sure if they're coming or going.
The surgeon is often deeply indebted to the radiologist for assistance in making diagnoses and for therapeutic radiological procedures. You may think of the radiologist as the physician who just reads chest xrays, but you'd be quite mistaken. These physicians have a huge armamentarium of procedures, involving xray, nuclear medicine, ultrasound, computerized scanning, interventional angiography, inserting catheters into blood vessels for diagnosis, treatment, dilating narrowed areas, placing drains, doing xray guided needle biopsies of the lung, liver, or breast, and magnetic resonance imaging, to name just a few. They have a detailed knowledge of anatomy, pathology, surgery, and medicine and often discuss with the surgeon what studies should be undertaken to make a diagnosis.
I want to describe some of the studies listed above just so you will have a better idea what you're in for should you need their diagnostic and therapeutic acumen.
First, there are the contrast studies of the intestinal tract, such as the upper gastrointestinal and small bowel series, where you swallow a special liquid and the radiologist can examine your esophagus, stomach, duodenum or the first part of the small intestine where ulcers sometime occur, and the entire small intestines. A barium enema is an exam of the lower intestinal tract via the rectum. All these studies can identify benign and malignant pathology, sometimes in anticipation of surgical intervention.
Angiograms are studies of blood vessels using contrast or dye. The uses are extensive, from studying vessels in the brain, to those in the heart. The coronary arteries study is done by cardiologists and may include the aorta, the vessels in the arms and legs and any other organ, such as the kidneys, liver, as well as the veins in the body. When pathology is found, it may need surgical intervention, but in the last twenty years radiologists and other specialists have developed techniques for percutaneous angiography and angioplasty. Catheters are placed through the skin without a big surgical incision, opening up closed vessels, dilating narrowings, placing filters in veins (see Pulmonary Embolism chapter),