A look at hematologic and lymphatic disorders
Because the hematologic system affects every body system, caring for a patient with a hematologic disorder can be especially challenging. For example, a patient’s dyspnea may lead you to suspect a respiratory or cardiovascular condition — when his primary problem is anemia.
To help ensure accurate diagnosis and effective care, you’ll need to obtain an especially thorough history and physical assessment. With astute, sensitive care founded on a firm understanding of hematologic basics, you can help patients survive these disorders. Even when the prognosis is poor, you can help patients make the necessary adjustments to maintain an optimal quality of life.
Anatomy and physiology
The hematologic system consists of blood — the major body fluid tissue — and the bone marrow, which manufactures new blood cells in a process called hematopoiesis. Blood delivers oxygen and nutrients to all tissues, removes wastes, and performs many other tasks.
Blood consists of various formed elements, or blood cells, suspended in a fluid called plasma. Formed elements of the blood include:
• red blood cells (RBCs), or erythrocytes
• platelets (thrombocytes)
• white blood cells (WBCs), or leukocytes.
RBCs and platelets function entirely within blood vessels. WBCs, in contrast, act mainly in the tissues outside the blood vessels.
Red blood cells
RBCs transport oxygen and carbon dioxide to and from body tissues. They contain hemoglobin (Hb), the oxygen-carrying substance that gives blood its red color. The RBC surface carries antigens (substances that trigger formation of antibodies that interact specifically with that antigen). These antigens determine a person’s blood group, or blood type.
Out with the old…
Constant circulation wears out RBCs, which have an average life span of 120 days. The spleen sequesters, or isolates, the old, wornout RBCs, removing them from circulation. This process requires the body to manufacture billions of new cells daily to maintain RBCs at normal levels.
… in with the new
The bone marrow releases RBCs into the circulation in an immature form called reticulocytes, which mature into RBCs in about 1 day. The rate of reticulocyte release usually equals the rate of old RBC removal. When RBC depletion occurs — for example, with hemorrhage — the bone marrow increases reticulocyte production to maintain normal RBC levels.
Blood falls into one of four types:
• In type A blood, the A antigen appears on RBCs.
• In type B blood, the B antigen appears.
• Type AB blood contains both the A and B antigens.
• Type O blood has neither the A antigen nor the B antigen.
Blood from any of these types may also contain the Rhesus (Rh) factor antigen. Blood with the Rh antigen is Rh-positive; blood without it is Rh-negative.
Plasma may contain antibodies (immunoglobulins) that interact with these antigens, causing the cells to agglutinate (clump together). However, plasma can’t contain antibodies to its own cell antigen, or it would destroy itself. Thus, type A blood has A antigen but no anti-A antibodies, although it does have anti-B antibodies.
This principle is important for blood transfusions: The donor’s blood type must be compatible with the recipient’s. Otherwise, the transfusion may be fatal. That’s why precise blood typing and crossmatching (mixing and observing for agglutination of donor cells) are essential.
Platelets are small, colorless, disk-shaped, cytoplasmic fragments split from very large bone marrow cells called megakaryocytes. Their life span is approximately 10 days.
Platelets perform three vital functions:
• They initiate contraction of damaged blood vessels to minimize blood loss.
• They form hemostatic plugs in injured blood vessels to help stop bleeding.
• Along with plasma, they provide materials that accelerate blood clot formulation, or coagulation.
White blood cells
Five types of WBCs (neutrophils, eosinophils, basophils, monocytes, and lymphocytes) participate in the body’s defense and immune systems. WBCs are classified as granulocytes or agranulocytes based on:
• shape of the nucleus (the sphere that contains the genetic codes for maintaining and reproducing that cell)
• presence or absence of granules (small particles) in the cytoplasm (all of the cell’s contents excluding the nucleus)
• affinity for laboratory stains or dyes.
Granulocytes contain a single multilobed nucleus and prominent cytoplasmic granules. Types of granulocytes include neutrophils, eosinophils, and basophils.
Polly wants a shorter name
Collectively, these cells are called polymorphonuclear leukocytes. However, each cell type exhibits different properties, and each is activated by different stimuli.
Neutrophils, the most abundant type of granulocyte, account for 48% to 77% of circulating WBCs. Like granulocytes, neutrophils are phagocytic.
Neutrophils leave the bloodstream by passing through intact capillary walls into surrounding tissues — a process called diapedesis. Then they migrate to and accumulate at infection sites.
Eating the enemy
Neutrophils are phagocytes — cells that engulf, ingest, and digest waste material, harmful microorganisms, and other foreign bodies. Consequently, they serve as the body’s first line of cellular defense against foreign organisms.
Strike up the bands
Worn-out neutrophils form the main component of pus. Bone marrow produces their replacements — immature neutrophils called bands. In response to infection, the bone marrow must produce many immature cells and release them into the circulation, which elevates the band count.
Eosinophils account for only 0.3% to 7% of circulating WBCs. These granulocytes also migrate from the bloodstream by diapedesis, but do so in response to an allergic reaction. Eosinophils accumulate in loose connective tissue, where they take part in ingesting antigen-antibody complexes.
Basophils usually account for less than 2% of circulating WBCs. These cells have little or no phagocytic ability. However, their cytoplasmic granules secrete histamine (a vasodilator) in response to certain inflammatory and immune stimuli. This action causes an increase in vascular permeability and eases fluid passage from capillaries into body tissues.
WBCs in this category — monocytes and lymphocytes — lack specific cytoplasmic granules and have nuclei without lobes.
Monocytes, the largest of the WBCs, constitute only 0.6% to 10% of WBCs in circulation. Like neutrophils, monocytes are phagocytic and diapedetic. Outside the bloodstream, they enlarge and mature, becoming tissue macrophages (also called histiocytes).
Protection from infection
As macrophages, monocytes may roam freely through the body when stimulated by inflammation. Usually, however, they remain immobile, populating most organs and tissues. Collectively, monocytes are components of the mononuclear phagocyte system (MPS), formerly called the reticuloendothelial system. The MPS defends against infection and disposes of cell breakdown products.
Macrophages concentrate in structures that filter large amounts of body fluid — such as the liver, spleen, and lymph nodes — where they defend against invading organisms. Macrophages are efficient phagocytes of bacteria, cellular debris (including worn-out neutrophils), and necrotic (dead) tissue. When mobilized at an infection site, they engulf and destroy cellular remnants and promote wound healing.
Lymphocytes, the smallest of the WBCs and the second most numerous (16% to 43%), derive from stem cells in the bone marrow. They exist in two types:
• T lymphocytes, which directly attack an infected cell
• B lymphocytes, which produce antibodies against specific antigens.
Many signs and symptoms of hematologic disorders are nonspecific. However, certain ones are more specific and can help you focus on possible disorders. These include:
• abnormal bleeding
• bone and joint pain
• exertional dyspnea
• shortness of breath
• ecchymoses (bruising)
• fatigue and weakness
• lymphadenopathy (enlarged lymph nodes)
• petechiae (tiny purplish spots caused by minute hemorrhages). If your patient has one of these more specific signs or symptoms, turn your attention to assessing his hematologic system.
Start your assessment by taking a thorough patient history. To increase the patient’s cooperation, develop a trusting relationship with him.
Current health status
Ask the patient why he’s seeking medical help. Document his response in his own words. Keep in mind that signs and symptoms of hematologic problems can appear in any body system, so patient complaints may be nonspecific — such as lack of energy, light-headedness, or nosebleeds.
Picking out patterns
Nonspecific complaints aren’t diagnostic in themselves. However, when considered in the context of a complete patient history, they may establish a pattern that suggests a hematologic disorder.
Previous health status
Ask about the patient’s medical history, which may provide clues to his present condition. Stay alert for disorders (such as acute leukemia, Hodgkin’s disease, or sarcoma) that necessitated aggressive immunosuppressant or radiation therapies. If your patient was hospitalized, ask why. Could a previous surgical intervention, such as a splenectomy, be causing a medical problem?
Has the patient received blood products? If so, note when and how many he received to help assess his risk of harboring an infection transmitted by transfusion.
Finally, document all the medications he’s taking — prescription and over-the-counter. Some medications interfere with various components of the hematologic system.
Ask about deceased family members, recording the cause of death and their ages at death. Note hereditary hematologic disorders, such as hemophilia, von Willebrand’s disease, and sickle cell anemia. Plot these disorders on a family genogram to determine the inheritance risk.
Ask your patient about:
• alcohol intake, diet, sexual habits, and possible drug abuse, which can impair hematologic function
• exposure to such hazardous substances as benzene or Agent Orange, which can cause bone marrow dysfunction (especially leukemia).
Because a hematologic disorder can involve almost every body system, be sure to conduct a complete physical examination.
A seemly sequence
When assessing the abdomen, be sure to inspect first, then auscultate, percuss, and palpate. Palpating or percussing the abdomen before you auscultate it can change the character of bowel sounds and lead to an inaccurate assessment.
Focus your inspection on the areas most relevant to a hematologic disorder — the skin, mucous membranes, fingernails, eyes, lymph nodes, liver, and spleen.
Skin and mucous membranes
Skin color directly reflects body fluid composition. Observe for pallor, cyanosis, and jaundice. Because normal skin color can vary widely among individuals, ask the patient if his present skin tone is normal.
Inspect the patient’s face, conjunctivae, hands, and feet for plethora (a ruddy color) — a symptom of polycythemia (a disorder marked by excess RBCs). Also look for erythema (redness) of the skin, which may indicate local inflammation or fever.
Next, assess the skin and mucous membranes for jaundice. Be sure to observe the patient in natural light rather than incandescent light, which can mask a yellowish tinge. With a dark-skinned patient, inspect the buccal mucosa, palms, and soles for a yellowish tinge. In a patient with edema, examine the inner forearm for jaundice.
Purplish purpuric patches
If you suspect a blood-clotting abnormality, check the skin for purpuric lesions — purplish spots or patches that vary in size and usually result from thrombocytopenia. With dark-skinned patients, check the oral mucosa or conjunctivae for petechiae or ecchymoses ( bruising).
Check the skin for dryness and coarseness, which may indicate iron deficiency anemia.
Mucous membrane appraisal
Finally, inspect the patient’s mucous membranes, especially the gingivae (gums). Look for bleeding, redness, swelling, and ulcers.
Inspect the patient’s fingernails for longitudinal striations, koilonychia (spoon nail), platyonychia (abnormally broad or flat nails), and nail clubbing (enlargement).
Examine the patient’s eyes for yellowish sclerae and for retinal hemorrhages and exudates.
Lymph nodes, liver, and spleen
Inspect the abdominal area for enlargement, distention, and asymmetry. Liver and spleen enlargement may result from congestion caused by blood cell overproduction (as in polycythemia or leukemia) or excessive blood cell destruction (as in hemolytic anemia).
With the patient lying down, auscultate the abdomen before palpation and percussion to avoid altering bowel sounds. Listen for loud, high-pitched tinkling sounds, which herald the early stages of intestinal obstruction.
Next, auscultate the liver and spleen. Listen carefully over both organs for friction rubs — grating sounds that fluctuate with respiration. These sounds usually indicate inflammation of the organ’s peritoneal covering.
Percussion of the liver and spleen
To determine liver and spleen size (and possibly detect tumors), percuss all four abdominal quadrants and compare your findings. The normal liver sounds dull. Establish the organ’s approximate size by percussing for its upper and lower borders at the midclavicular line. To determine medial extension, percuss to the midsternal landmark.
How dull can it get?
Like the liver, the normal spleen sounds dull. Percuss it from the midaxillary toward the midline. The average-sized spleen lies near the eighth, ninth, or tenth intercostal space. You might want to mark liver and spleen borders with a pen for later reference during palpation of these organs.
Palpation of the lymph nodes, liver, and spleen
Palpate the patient’s neck, axillary, epitrochlear, and inguinal lymph nodes. Using your finger pads, move the skin over each area. As you palpate each node, note its location, size, tenderness, texture (hard, soft, or firm), and fixation (whether it’s movable or fixed). For each node group, note the symmetry.
Accurate liver palpation is difficult and can depend on the patient’s size, present comfort level, and whether fluid is present. If necessary, repeat the procedure, checking your hand position and the pressure you exert.
Lightly palpate all four abdominal quadrants to distinguish tender sites and muscle guarding. Deeper palpation helps delineate abdominal organs and masses. Be sure to palpate tender areas last. Avoid continued palpation if a tumor is suspected.
Diagnostic tests allow direct analysis of the blood, its formed elements, and the bone marrow. Such tests include agglutination tests, coagulation screening tests, and bone marrow aspiration and biopsy.
Agglutination tests evaluate the ability of the blood’s formed elements to react to foreign substances by clumping together. They include ABO blood typing, crossmatching, and Rh blood typing.
ABO blood typing
ABO blood typing classifies blood into A, B, AB, or O groups according to the presence of major antigens A and B on RBC surfaces, and according to serum antibodies anti-A and anti-B.
Go forward, then reverse
To prevent a lethal transfusion reaction, both forward and reverse blood typing are required. In forward typing, a blood sample is mixed with serum containing anti-A antibodies; another sample isthen mixed with serum that contains anti-B antibodies. Clotting patterns are observed and recorded. In reverse typing, the blood sample is mixed with type A and type B blood, and clotting patterns are observed and recorded.
• Before the patient receives a transfusion, compare current and past ABO typing and cross matching to detect mistaken identification and help prevent transfusion reactions. Remember — if the recipient’s blood type is A, he may receive type A or O blood. If his blood type is B, he may receive type B or O blood. If his blood type is AB, he may receive type A, B, AB, or O blood. If his blood type is O, he may receive only type O blood.
• Note that recent administration of dextran or I.V. contrast media causes cells to aggregate similarly to agglutination. If the patient received blood during the past 3 months, antibodies to the donor blood may have developed and lingered, interfering with compatibility testing.
Crossmatching establishes whether donor and recipient blood are compatible and serves as the final check for such compatibility. Lack of agglutination indicates compatibility between donor and recipient blood, which means the blood transfusion can proceed.
Crossmatching in a crisis
Blood is always crossmatched before transfusion, except in extreme emergencies. A complete crossmatch may take 45 minutes to 2 hours, so an incomplete (10-minute) crossmatch may be acceptable in an emergency.
An emergency transfusion must proceed with special awareness of the complications that may result from incomplete typing and crossmatching. After crossmatching, compatible units of blood are labeled and a compatibility record is completed.
• If more than 48 hours have elapsed since the previous transfusion, previously crossmatched donor blood must be crossmatched with a new recipient blood sample to detect newly acquired incompatibilities before transfusion.
• If the recipient hasn’t received the transfusion, donor blood need not be crossmatched again for 72 hours. Check facility transfusion protocols.
• If the patient is scheduled for surgery and has received blood during the previous 3 months, his blood must be crossmatched again to detect recently acquired incompatibilities.
Rh blood typing
The Rh system classifies blood by the presence or absence of the Rho(D) antigen on the surface of RBCs. This test is used to establish blood type according to the Rh system to determine if the donor and recipient are compatible before transfusion.
Get right with Rh
Classified as Rh-positive, Rh-negative, or Rh-positive Du, donor blood may be transfused only if it’s compatible with the recipient’s blood. (Du is an Rho[D] variant.)
Encourage the patient to carry a blood group identification card in his wallet to protect him in an emergency. Most laboratories will provide such a card on request.
Coagulation screening tests
Coagulation screening tests help detect bleeding disorders and specific coagulation defects. Commonly ordered coagulation tests include partial thromboplastin time (PTT), bleeding time, plasma thrombin time, and prothrombin time (PT). (See Common coagulation tests.)
• Perform a clean venipuncture. Blood contaminated with tissue thromboplastin causes misleading test results.
• Place the blood sample on ice immediately after obtaining it to preserve its labile factors.
• Allow no more than 4 hours between blood sampling and coagulation testing. Allow only 2 hours between blood centrifugation and coagulation testing; after being centrifuged, RBCs lose their buffering effect on the plasma.
Biopsy procedures involve removing a small tissue sample for further testing. Bone marrow aspiration is an important test for evaluating the blood’s formed elements.
Bone marrow aspiration and needle biopsy
Because most hematopoiesis occurs in the bone marrow, histologic and hematologic bone marrow examination yields valuable diagnostic information about blood disorders. Bone marrow aspiration and needle biopsy provide the material for this examination.
Doubling the diagnostic odds
Aspiration biopsy removes a fluid specimen containing bone marrow cells in suspension. Needle biopsy removes a marrow core containing cells but no fluid. Using both methods provides the best possible marrow specimens. Bone marrow biopsy helps:
• diagnose aplastic, hypoplastic, and vitamin B12 deficiency anemias; granulomas; leukemias; lymphomas; myelofibrosis; and thrombocytopenia
• evaluate primary and metastatic tumors
• determine infection causes
• stage such diseases as Hodgkin’s disease
• evaluate chemotherapy effectiveness
• monitor myelosuppression.
Hematologic analysis, including the WBC differential and myeloid-erythroid ratio, can suggest various disorders.
• When preparing your patient, explain that the test provides a bone marrow specimen for microscopic examination. Inform him that he need not restrict food or fluids beforehand. Explain who will perform the biopsy, that it usually takes only 5 to 10 minutes, and that results usually are available in 1 day. Inform him that more than one bone marrow specimen may be necessary and that before the biopsy, he’ll need to give a blood sample for laboratory testing.
• Check the patient’s history for hypersensitivity to the local anesthetic, and make sure the patient’s medical record includes a signed consent form.
• After checking with the person who will perform the procedure, tell the patient which bone will serve as the biopsy site (usually the posterior iliac crest). Inform him that he’ll receive a local anesthetic but will feel pressure with biopsy needle insertion and a brief pulling pain with marrow removal.
• As ordered, administer a mild sedative 1 hour before the test.
• After the procedure, check the biopsy site for bleeding and inflammation. Observe the patient for signs of hemorrhage and infection — rapid pulse rate, low blood pressure, and fever. Change the dressing over the biopsy site every 24 hours to reduce the risk of infection.