pregnancy test


Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.
Related to pregnancy test: Pregnancy symptoms

pregnancy test

See HCG radioreceptor assay.

pregnancy test

Any test used to detect or confirm pregnancy; in early pregnancy, all PTs measure hCG, the developing placenta's principal hormone, which is detectable as early as 6 days after fertilization; in clinical laboratories, serum levels of hCG are quantified by ELISA or RIA; home testing kits are reliable, widely used, operate on the principle of agglutination, and have < 1% error rate Ref range Nonpregnant < 5 mIU/mL. See hCG, Estriol.

pregnancy test

A test used to determine whether conception has occurred. In addition to the clinical signs and symptoms of pregnancy, almost none of which are reliable within the first several weeks of pregnancy, chemical tests done in the physician's office are quite accurate by as early as the time the first menstrual period is missed. There are also test kits available for purchase without a prescription. If over-the-counter tests are used, it is very important to follow the directions carefully.

A major class of pregnancy tests is those using immunodiagnostic procedures. They are the hemagglutination inhibition test, which requires a sample of urine; radioreceptor assay, which requires blood from the patient; radioimmunoassay, which requires a blood sample; and monoclonal antibody determination, which requires a sample of urine. In general, these tests are accurate beginning the 40th day following the first day of the last menstrual period; the monoclonal antibody test is somewhat more sensitive. The reliability of the test methods increases as pregnancy continues.

Human Chorionic Gonadotropin

Synonym/acronym: Chorionic gonadotropin, pregnancy test, HCG, hCG, α-HCG, β-subunit HCG.

Common use

To assist in verification of pregnancy, screen for neural tube defects, and evaluate human chorionic gonadotropin (HCG)–secreting tumors.

Specimen

Serum (1 mL) collected in a gold-, red-, or red/gray-top tube. Plasma (1 mL) collected in a green-top (heparin) tube is also acceptable.

Normal findings

(Method: Immunoassay)
Conventional UnitsSI Units (Conventional Units × 1)
Males and nonpregnant femalesLess than 5 milli international units/mLLess than 5 international units/L
Pregnant females by week of gestation:
 2 wk5–100 milli international units/mL5–100 international units/L
 3 wk200–3,000 milli international units/mL200–3,000 international units/L
 4 wk10,000–80,000 milli international units/mL10,000–80,000 international units/L
 5–12 wk90,000–500,000 milli international units/mL90,000–500,000 international units/L
 13–24 wk5,000–80,000 milli international units/mL5,000–80,000 international units/L
 26–28 wk3,000–15,000 milli international units/mL3,000–15,000 international units/L

Description

Human chorionic gonadotropin (HCG) is a hormone secreted by the placenta beginning 8 to 10 days after conception, which coincides with implantation of the fertilized ovum. It stimulates secretion of progesterone by the corpus luteum. HCG levels peak at 8 to 12 wk of gestation and then fall to less than 10% of first trimester levels by the end of pregnancy. By postpartum week 2, levels are undetectable. HCG levels increase at a slower rate in ectopic pregnancy and spontaneous abortion than in normal pregnancy; a low rate of change between serial specimens is predictive of a nonviable fetus. As assays improve in sensitivity over time, ectopic pregnancies are increasingly being identified before rupture. HCG is used along with α-fetoprotein, dimeric inhibin-A, and estriol in prenatal screening for neural tube defects. These prenatal measurements are also known as triple or quad markers, depending on which tests are included. Serial measurements are needed for an accurate estimate of gestational stage and determination of fetal viability. Triple- and quad-marker testing has also been used to screen for trisomy 21 (Down syndrome). (To compare HCG to other tests in the triple- and quad-marker screening procedure, see monograph titled “α1-Fetoprotein.”) HCG is also produced by some germ cell tumors. Most assays measure both the intact and free β-HCG subunit, but if HCG is to be used as a tumor marker, the assay must be capable of detecting both intact and free β-HCG.

This procedure is contraindicated for

    N/A

Indications

  • Assist in the diagnosis of suspected HCG-producing tumors, such as choriocarcinoma, germ cell tumors of the ovary and testes, or hydatidiform moles
  • Confirm pregnancy, assist in the diagnosis of suspected ectopic pregnancy, or determine threatened or incomplete abortion
  • Determine adequacy of hormonal levels to maintain pregnancy
  • Monitor effects of surgery or chemotherapy
  • Monitor ovulation induction treatment
  • Prenatally detect neural tube defects and trisomy 21 (Down syndrome)

Potential diagnosis

Increased in

  • Choriocarcinoma (related to HCG-producing tumor)
  • Ectopic HCG-producing tumors (stomach, lung, colon, pancreas, liver, breast) (related to HCG-producing tumor)
  • Erythroblastosis fetalis (hemolytic anemia as a result of fetal sensitization by incompatible maternal blood group antigens such as Rh, Kell, Kidd, and Duffy is associated with increased HCG levels)
  • Germ cell tumors (ovary and testes) (related to HCG-producing tumors)
  • Hydatidiform mole (related to HCG-secreting mole)
  • Islet cell tumors (related to HCG-producing tumors)
  • Multiple gestation pregnancy (related to increased levels produced by the presence of multiple fetuses)
  • Pregnancy (related to increased production by placenta)

Decreased in

    Any condition associated with diminished viability of the placenta will reflect decreased levels.

    Ectopic pregnancy (HCG levels increase slower than in viable intrauterine pregnancies, plateau, and then decrease prior to rupture) Incomplete abortion Intrauterine fetal demise Spontaneous abortion Threatened abortion

Critical findings

    N/A

Interfering factors

  • Drugs that may decrease HCG levels include epostane and mifepristone.
  • Results may vary widely depending on the sensitivity and specificity of the assay. Performance of the test too early in pregnancy may cause false-negative results. HCG is composed of an α and a β subunit. The structure of the α subunit is essentially identical to the β subunit of follicle-stimulating hormone, luteinizing hormone, and thyroid-stimulating hormone. The structure of the β subunit differentiates HCG from the other hormones. False-positive results can therefore be obtained if the HCG assay does not detect β subunit.

Nursing Implications and Procedure

Potential nursing problems

ProblemSigns & SymptomsInterventions
Spirituality (Related to potential or actual; fear of fetal death; loss of potential child)Forgiveness; acceptance; anger at spiritual leaders; expressed feelings of hopeless, powerlessness; abandonment; refusals or inability to participate in spiritual activities (prayer); expresses feelings over lack of meaning with life or serenityEncourage the verbalization of feelings in a safe, nonjudgmental environment; assess the desire for contact from associated spiritual leader; foster a supportive relationship with the patient and family; encourage a display of objects (spiritual, religious) that provide emotional relief; assess for expressions of hope
Fear (Related to possible loss of potential child; ineffective coping; unfamiliar therapeutic regime; unknown)Expression of fear; preoccupation with fear; increased tension; increased blood pressure; increased heart rate; vomiting; diarrhea; nausea; fatigue; weakness; insomnia; shortness of breath; increased respiratory rate; withdrawal; panic attacksProvide specific education related to pregnancy confirmation and identification of viability; provide specific information related to ongoing pregnancy; communicate with social services for needed support; ensure education is culturally appropriate; assist the patient and family to recognize effective coping strategies; assist the patient and family to acknowledge their fear; provide a safe environment to discuss fear; explore cultural influences that may enhance fear; utilize therapeutic touch as appropriate to decrease fear
Family process (Related to failure to maintain a viable pregnancy)Stated feelings of failing to provide children; change in communication patterns between partners regarding having children; alterations in intimacyOffer family counseling; facilitate opportunities for the patient and spouse to express their feelings and their perception of the problem; evaluate patient and family weaknesses, strengths, and coping strategies; help the family and patient break down concerns into manageable parts
Grief (Related to fetal loss; inability to carry child to term)Apparent psychological and emotional distress; withdrawal; detachment; loss of appetite; refusal to participate in activities of daily living; anger; blame Assess decision-making ability; encourage expression of grief; provide contact information for grief support group; assist to identify current support group; provide social services referral as appropriate; allow the patient and spouse to relieve the loss and express feelings

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this test can assist in screening for pregnancy, identifying tumors, and evaluating fetal health.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s endocrine, immune, and reproductive systems; symptoms; and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Record the date of the last menstrual period and determine the possibility of pregnancy in perimenopausal women.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Note that there are no food, fluid, or medication restrictions unless by medical direction.

Intratest

  • Potential complications: N/A
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
  • Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
  • Promptly transport the specimen to the laboratory for processing and analysis.

Post-Test

  • Inform the patient that a report of the results will be made available to the requesting health-care provider (HCP), who will discuss the results with the patient.
  • Social and Cultural Considerations: Recognize anxiety related to abnormal test results, and encourage the family to seek counseling if concerned with pregnancy termination or to seek genetic counseling if a chromosomal abnormality is determined. Provide teaching and information regarding the clinical implications of the test results, as appropriate. Decisions regarding elective abortion should take place in the presence of both parents. Provide a nonjudgmental, nonthreatening atmosphere for discussing the risks and difficulties of delivering and raising a developmentally challenged infant, as well as exploring other options (termination of pregnancy or adoption). It is also important to discuss feelings the mother and father may experience (e.g., guilt, depression, anger) if fetal abnormalities are detected.
  • Social and Cultural Considerations: Offer support, as appropriate, to patients who may be the victims of rape or sexual assault. Educate the patient regarding access to counseling services. Provide a nonjudgmental, nonthreatening atmosphere for a discussion during which risks of sexually transmitted diseases are explained. It is also important to discuss problems the victim of sexual assault may experience (e.g., guilt, depression, anger) if there is possibility of pregnancy related to the assault.
  • Social and Cultural Considerations: In patients with carcinoma, recognize anxiety related to test results and offer support. Provide teaching and information regarding the clinical implications of abnormal test results, as appropriate. Educate the patient regarding access to counseling services, as appropriate.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor the patient’s condition and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.
  • Patient Education

    • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP.
    • Instruct the patient in the use of home test kits for pregnancy approved by the U.S. Food and Drug Administration, as appropriate.
    • Answer any questions or address any concerns voiced by the patient or family.
  • Expected Patient Outcomes

    • Knowledge
    • States understanding that surgical intervention may be necessary in the event of fetal demise.
    • States understanding that the purpose of surgical intervention post-miscarriage is to ensure all of the tissue is removed to prevent infection and facilitate future viable pregnancies.
    • Skills
    • Accurately describes symptoms that may indicate a miscarriage and should be reported to the HCP.
    • Accurately describes the purpose of future laboratory (HCG) studies to monitor and verify the continuation of the pregnancy.
    • Attitude
    • Agrees to attend a support group for those who have experienced fetal loss.
    • Complies with scheduled follow-up laboratory studies to monitor pregnancy.

Related Monographs

  • Related tests include biopsy chorionic villus, Chlamydia group antibody, chromosome analysis, CMV, estradiol, fetal fibronectin, α1-fetoprotein, CBC, hematocrit, CBC hemoglobin, CBC WBC count and differential, progesterone, rubella antibody, rubeola antibody, syphilis serology, toxoplasma antibody, US abdomen, and US biophysical profile obstetric.
  • Refer to the Endocrine, Immune, and Reproductive systems tables at the end of the book for related tests by body system.
References in periodicals archive ?
The launch of this newly redesigned First Response pregnancy test stick is a big step in addressing women's needs in an evolving landscape," said Dr.
A spokesman for The Medicine and Healthcare products Regulatory Agency said: "We recognise the concern felt by those who believe they or their children may have been AFFECTED by the use of these hormonal pregnancy tests.
All patients presenting with a positive pregnancy test were contacted by one of our investigators to confirm the result.
The combination of the pregnancy test and the symptom checklist during telephone follow-up had 93% sensitivity and 91% specificity for detecting ongoing pregnancy.
A private little revolution": the home pregnancy test in American culture.
A urine-based pregnancy test was found in an ancient Egyptian document from 1350 BCE wherein a pregnant woman's urine promoted growth of barley (male child) or wheat (female child)--or neither (no child).
In such situations, performing a pregnancy test without consent may be the only way that a health care professional would know about such abuse, and the only way to help her.
12) In addition, women were asked what they would do if they received a positive pregnancy test result ("choose abortion," "continue to adoption," "continue to parenthood" or "don't know").
The dollar store pregnancy tests appeared able to detect HCG at the same low levels as the QuickVue urine pregnancy test, and also to be easier to read than the more expensive test," Dr.
The court made it clear that it found much lacking in Nurse Lloyd's testimony, including the fact she testified that she "could not remember" whether she informed surgeons of negative pregnancy test results.
27, the Catholic bishops and leaders of Catholic hospitals in the state said that although they continue to believe that the law is flawed and should be changed, they would revise current protocols at the hospitals that call for both a pregnancy test and an ovulation test before the "morning-after" pill marketed as Plan B is administered.
Q I'VE missed three periods and have had a pregnancy test done but it came back negative.