Question

Which results of a CBC (complete blood count) with differential should the nurse interpret as indicating the client has a severe bacterial infection? A. WBC 8,500; lymphocytes 45\% B. WBC 15,000; segmented neutrophils \(50 \%\) C. WBC 25,000 ; band neutrophils \(20 \%\) D. WBC 20,000 ; segmented neutrophils \(58 \%\)

Short answer

C) WBC 25,000; band neutrophils 20%

Step-by-step solution

- Understand CBC parameters

Complete Blood Count (CBC) includes various parameters such as White Blood Cells (WBC), lymphocytes, neutrophils, etc. A normal WBC value is typically between 4,000 to 11,000 cells per microliter. Neutrophils, including segmented and band neutrophils, are often elevated in bacterial infections.

- Identify significant elevations

Determine which options show elevated WBC typically above 11,000, indicating an infection. Compare options: A) WBC 8,500, B) WBC 15,000, C) WBC 25,000, D) WBC 20,000. Options B, C, and D are above the upper limit.

- Analyze neutrophil percentages

Neutrophils are divided into segmented (mature) and band (immature) forms. A high percentage of band neutrophils (>10%) often signifies severe bacterial infection. Check the percentages: B) 50% segmented, C) 20% band, D) 58% segmented. Option C stands out with 20% band neutrophils.

- Conclusion

Based on the WBC count and the high percentage of band neutrophils, Option C) WBC 25,000; band neutrophils 20% is the most indicative of a severe bacterial infection.

Key concepts

Complete Blood Count Interpretation

A Complete Blood Count (CBC) is a critical diagnostic tool used to evaluate and monitor overall health and detect a wide range of disorders. It measures several key components of blood. The primary elements include

• White Blood Cells (WBC)
• Red Blood Cells (RBC)
• Platelets (PLT)

. Among these, WBCs play an essential role in the immune response.
For a CBC with differential, each type of white blood cell is counted, providing detailed insights. This includes

• Neutrophils
• Lymphocytes
• Monocytes
• Eosinophils
• Basophils

. Each type has a unique function in defending the body against infections and other diseases.
To interpret a CBC, understanding normal ranges is vital. For example, normal WBC values typically range from 4,000 to 11,000 cells per microliter. Deviations from these ranges can indicate various health issues. An elevated WBC count often points to an infection, inflammation, or other immune responses. Detailed analysis of these counts helps identify specific conditions such as bacterial infections.

White Blood Cells Significance

White Blood Cells (WBCs) are crucial components of the immune system, tasked with identifying and combating infections. They are the body's primary defense against infectious agents. Normal WBC counts range between 4,000 to 11,000 cells per microliter, with increases often indicating the presence of an infection or inflammatory response.
WBCs are categorized into five main types, each serving specific functions:

• Neutrophils: Respond quickly to infections, especially bacteria, and engulf pathogens.
• Lymphocytes: Include B cells and T cells, both of which are key to the adaptive immune response.
• Monocytes: Transform into macrophages and digest cellular debris and pathogens.
• Eosinophils: Involved in allergic responses and combating parasitic infections.
• Basophils: Release histamine during allergic reactions and help defend against parasites.

Understanding the differential count (percentage of each type) offers a comprehensive view of the immune status and aids in diagnosing diverse conditions like bacterial infections, viral infections, and allergic reactions.

Neutrophil Types in Infections

Neutrophils are the most abundant type of white blood cells and play a pivotal role in the body's defense against bacterial infections. They are divided into two categories:

• Segmented neutrophils: Mature neutrophils that form the first line of defense.
• Band neutrophils: Immature neutrophils released from bone marrow during acute infection when the demand for neutrophils exceeds supply.

The presence of a high number of band neutrophils, a condition known as a 'left shift', often indicates a severe bacterial infection.
When interpreting a CBC with differential:

• A WBC count elevated above the typical upper limit of 11,000 cells per microliter suggests an active infection or inflammation.
• An increase in the neutrophil count, particularly band neutrophils when above 10%, signals that the body is fighting a severe bacterial infection.

. For instance, in the exercise, Option C (WBC 25,000; band neutrophils 20%) is highly indicative of a severe bacterial infection due to the significantly elevated WBC and band neutrophils. Such insights guide healthcare professionals in making informed clinical decisions to manage infections effectively.