Diagnosing Sepsis

Sepsis, also known as blood poisoning, is the body’s hyperactive response to an infection that can lead to inflammation, tissue damage, organ failure etc. It is a very dangerous state in which the immune system stops fighting with the invading agents  and turns to itself. Around one-third of patients who are affected with sepsis die every year.

Credit: Kateryna Kon/Shutterstock.com

Diagnosing sepsis is not an easy task as there is no particular symptom or sign that are directly related to the disease. Doctors doubt sepsis when the patient exhibit more than two infections or related signs. Thus, the diagnosis of sepsis needs a high level of suspicion, through the study of history and physic of the person, appropriate laboratory checkups, and close follow-up of hemodynamic status of the patient.

Evaluation of symptoms:

Many diseases like pneumonia and diverticulosis that are caused by gram negative or positive bacteria, viruses or even fungi can be related to sepsis. If the patient shows a number of symptoms and infections, and do fall into a risk category, he/she can be doubted for sepsis.

In such cases, the doctor will look for all the signs exhibited and examine them thoroughly. It is advisable not to wait for the confirmation results for starting treatment for sepsis. If the treatment begins at the stage of suspicion itself, the patient gets a chance of better recovery.

Evaluation of patient history:

Evaluation of patient history, in this case, is done to get information on three things.

  • Whether the infection that caused sepsis was community acquired.
  • Whether it is nosocomically acquired (acquired from the hospital).
  • Whether the patient has an impaired immune system.

Details of situation that can expose the patient to specific infectious agents are collected. For example fever, hypotension, exposure to animals, alcohol use, medications, loss of consciousness etc.

Physical examination:

If the patient has neutropenic or other pelvic infections, physical examination that can reveal rectal, perirectal, or perineal abscesses, pelvic inflammatory disease or abscesses, or prostatitis should be done. It includes rectal, pelvic, and genital examinations.

Laboratory tests:

For patients suspected with sepsis, a large number of tests are ordered so that the doctor gets details on the potentiality and severity of the patient's condition. It also helps to know the causes of sepsis-like microbial infections or processes.

The different tests done include urine test, blood test and tests related to other medical conditions.

Blood test

For patients with possible signs of sepsis, there are a number of blood tests available. Even though those tests cannot diagnose sepsis, combining the results with other information can help.

Various blood tests available are:

  1. Complete blood count (CBC): this test measures the count of white blood cell that helps in fighting microbes in the blood. A higher number of WBCs indicates infection while lower numbers say that there is a chance for infection.
  2. Lacate: This finds the presence of lactic acid in the blood, which is an indication of low oxygen level in the blood.
  3. C-reactive protein (CRP) test: C-reactive protein is an indication of inflammation in the body.
  4. Blood culture: This test tries to identify the type of bacteria or other microorganisms that serve as the cause for infection.
  5. Prothrombin time (PT) and partial thromboplastin time (PTT), platelet count, and d-dimer tests:  All these tests are related with blood clotting. High PT and PTT indicate poor blood clotting. Low platelet level indicates unseen clotting in tiny vessels all over the body. An indication of one large clot or many small clotting in the body is identified by the high level of d-dimer.

Confirmatory tests

There are three types of blood tests that can confirm sepsis. They are:

  1. Endotoxin test: Presence of endotoxin in blood confirms the presence of gram-negative bacteria in your bloodstream, even though the type cannot be identified.
  2. Procalcitonin (PCT) test: Low PCT level in the blood means that the disease is not caused by bacteria, but may be by a viral infection or an illness not related to an infection.
  3. SeptiCyte test: The products of sepsis-related genes are diagnosed through this test to check if those genes are activated.

Urine test

Two types of urine tests are ordered in cases of sepsis.

  1. Urinalysis: This tests urinary tract infection (UTI) or problems with your kidneys.
  2. Urine culture: Used to determine which bacteria or fungi caused UTI.

Tests for related medical condition(s):

Apart from blood and urine tests, tests related to other diseases that can cause sepsis are also done.

Few examples are:

  • Chest x-ray, pulse oximetry and sputum test for pneumonia.
  • Lumbar puncture, Magnetic resonance imaging (MRI) and Computerized tomography (CT) scan for meningitis.
  • The rapid antigen test and the throat culture for strep throat.
  • Rapid influenza diagnostic tests and symptom analysis for influenza.
  • Skin culturing for infections related to skin.

Reviewed by Afsaneh Khetrapal BSc (Hons)

Further Reading

Last Updated: Sep 7, 2017

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