S | Nurse Key

Severe acute respiratory syndrome tests

NURSING CARE

Pretest

• All specimens are potentially hazardous and are collected under conditions of strict precautions. The laboratory and the epidemiology departments are contacted before the specimens are collected.

• Because of the high risk of nosocomial spread of the virus, the nurse implements precautions for aerosol droplet and person-to-person contact including gown, double gloves, goggles, and face mask (N-95 respirator). Handwashing is essential. Guided by the department of epidemiology, the nurse ensures that all personnel follow correct infection control procedures at all times.

During the test

• When tracheal suctioning, endotracheal tube insertion or suctioning, or bronchoscopy is used to obtain sputum, the risks increase of transmission by aerosolization. To do the test, the patient must be placed in a negative-pressure room and any health care personnel in the room must wear the protective equipment identified previously.

Posttest

• The specimens are labeled with correct patient identification, the date, time, name of the physician, and the source of the specimen. The specimens are bagged and packed in ice, according to infection control procedures and procedures for biohazards. Usually, the hospital laboratory works with the Centers for Disease Control and Prevention (CDC) regarding analysis of the specimens. On completion of the collection procedures, all personnel in the room must wash their hands before exiting the room.

Sickle cell tests

Includes: High Performance Liquid Chromatography (HPLC), Hemoglobin electrophoresis, Sickle cell solubility test (Sickledex)

Purpose of the test

The sickle cell tests of high performance liquid chromatography or hemoglobin electrophoresis are methods of analysis to detect variant (abnormal) hemoglobin S (HbS) of the newborn and to confirm the diagnosis of sickle cell disease or trait. The sickle cell solubility test (Sickledex) is used to screen for the presence of hemoglobin S in the blood, but it cannot differentiate between sickle cell disease and sickle cell trait.

Basics the nurse needs to know

Sickle cell hemoglobin (HbS) is the most common of the variant hemoglobins. The term sickled is used because when there is low level of oxygen in the blood, HbS converts the erythrocytes into sickle or crescent shapes (Figure 87). In sickle cell disease, these damaged erythrocytes carry less oxygen to cells and tissues. Ongoing hemolysis of the damaged erythrocytes also occurs and causes chronic hemolytic anemia throughout life. In a sickle cell crisis, the many sickled cells become trapped in small blood vessels, causing obstruction, infarction, thrombus, or embolus in the circulation, with acute or chronic damage to organs and tissues.

Figure 87. Sickled cells differ in shape from normal erythrocytes.

Sickle cell trait or disease is an autosomal recessive genetic disorder. The homozygous (pure) form of HbS causes the disease of sickle cell anemia (HbSS). Abnormal chromosomes that produce hemoglobin S were inherited from both parents. The heterozygous (mixed) form of HbS produces sickle cell trait. The person with sickle cell trait inherited the HbS chromosome from one parent but not the other. The person with the trait condition does not have sickle cell anemia and under normal physiologic conditions will not develop a vaso-occlusive crisis (Pack-Maybien & Haynes, 2009).

Newborn testing to diagnose sickle cell anemia is done by high performance liquid chromatography or hemoglobin electrophoresis. Both have a very high rate of accuracy in detection of hemoglobin S. In the United States, the required testing is mandated within the first 1 to 3 days after birth, before the neonate leaves the birth setting. Follow-up verification testing is done when the infant has the first visit to the health care provider, but no later than 2 months after birth. If the infant is diagnosed with sickle cell disease, this schedule allows time for early treatment of the baby with prophylactic penicillin and pneumococcal pneumonia vaccination. Follow-up DNA testing may also be used to confirm or exclude sickle cell disease.

The sickle cell solubility test (Sickledex) is an additional screening test that may be used. This test cannot differentiate between sickle cell trait and sickle cell anemia, but with a positive result, follow-up testing with one of the other methods described above will provide the definitive diagnosis. The Sickledex test cannot be used with the neonate but is effective at ages 3 to 6 months and on older children or adults who were not screened at birth.

REFERENCE VALUES

Negative; No hemoglobin S is present

How the test is done

Heelstick capillary puncture is used to obtain a specimen of blood from the heel of the neonate.

Capillary puncture in the finger is used for older children and adults.

Significance of test results

Positive values

Sickle cell anemia

Sickle cell trait

Interfering factors

• Blood transfusion within the past 3 to 4 months

NURSING CARE

Nursing measures include care of the capillary puncture site as described in Chapter 2, with the following additional measures.

Pretest

• No special nursing intervention is needed.

Posttest

Health promotion

In all states of the United States and its territories, all newborns now have mandated screening for sickle cell disease, regardless of ethnicity (U.S. Preventive Services Task Force, 2007).

• The health care provider and the genetics counselor inform the parents about the test results, and when the results are positive, provide time for the parents to discuss and understand the results.

• The nurse provides support and clarification to the parents who have an infant who tested positive for sickle cell disease or trait. The parents often have feelings of concern, guilt, and fear about the well-being of their infant. In discharge planning, the nurse encourages the parents to keep all appointments with the health care provider for follow-up care for their infant. With sickle cell disease, early preventive measures and comprehensive disease management will greatly reduce the incidence of vaso-occlusive crises and effectively prolong the patient’s life.

• When one child of the family tests positive for the trait or disease, the nurse encourages testing of all members of the family. If the individual knows his or her genetic status regarding this mutation, he or she can make informed decisions regarding health and reproduction.

Sigmoidoscopy and anoscopy

Purpose of the test

Sigmoidoscopy is used as a screening test for cancer of the colon. It also is used to investigate the source of unexplained rectal bleeding or infection in the lower colon, to evaluate the postoperative anastomosis of the lower colon, and to diagnose or monitor inflammatory bowel disease. Anoscopy is used to investigate anal and rectal symptoms, such as bleeding, pain, discomfort, or prolapse. Sigmoidoscopy is often performed with anoscopy.

Basics the nurse needs to know

Sigmoidoscopy uses a flexible, fiberoptic endoscope (sigmoidoscope) to examine the sigmoid colon and rectum. About 50% of colon cancer and polyps of the colon are located in the left colon between the anus and the splenic flexure. During a sigmoidoscopy procedure, the polyps can be removed and suspicious tissue can be biopsied or cultures taken. The examination can be done in the physician’s office, without conscious sedation or pain medication. One of the drawbacks of sigmoidoscopy is that the other 50% of the polyps and cancerous tumors are located between the right colon and transverse colon, beyond the view of the sigmoidoscope. In addition, if a polyp or tumor is encountered by sigmoidoscopy, the patient will need a follow-up colonoscopy to view the remainder of the colon.

Anoscopy uses a short tubular instrument with a light to examine the rectum and anal canal. The anoscopy examination allows for visualization of the mucosa, with identification of problems of bleeding, fistula, infection, inflammation, or other abnormality.

There is a low prevalence of anal cancer in the general population. However, there is a rising incidence of anal cancer in HIV-infected men who have sex with men. Testing for the human papilloma virus (HPV) may be done during the anoscopy examination. When indicated, the anal examination can include a male PAP smear and the cell brushings can be examined microscopically for abnormal cytology. The Bethesda system is used to grade the anal cytologic changes (see Box 8, p. 471). A biopsy will be taken of anal cells that are graded as high-grade dysplasia (precancerous) or cancerous for a definitive diagnosis.

REFERENCE VALUES

No tissue abnormalities are seen in the sigmoid colon, rectum, or anus

The patient is placed in a lateral position on the examination table (Figure 88). The well-lubricated instrument is inserted into the anus and advanced to the desired depth. A tissue biopsy, PAP smear, or culture specimen may be obtained during the procedure. The time needed for the examination is 5 to 10 minutes.