Fetal Diagnostic Tests

Mrs. Roselyn S. Pacardo, RM, RN, MM, MAN Instructor

Al Yves Roman A. Lascuña BSN – 3E Student

Fetal Diagnostic Tests Diagnostic Test

Description

Purpose or Indication

Nursing Responsibility

Normal Values

Amniotic Fluid Analysis

☺This is the analysis of the fluid placed in an amber or a foil-covered test tube which was aspirated from the amniotic cavity of a pregnant woman. ☺A 10 ml syringe is used to attach to a 20G spinal needle with a stylet inserted into the amniotic cavity after the stylet is withdrawn.

☺To detect fetal abnormalities, particularly chromosomal and neural tube defects ☺To detect hemolytic disease of the neonate ☺To diagnose metabolic disorders, amino acid disorders, and mucopolysaccharadosis ☺To determine fetal age and maturity ☺To assess fetal health by detecting the presence of meconium or blood or measuring amniotic levels of estriol and fetal thyroid hormones

Before: ☺Explain procedure and answer patient’s questions ☺Inform patient that she need not restrict food and fluids ☺Explain to the patient that she’ll feel a stingning sensation when the local anesthetic is injected ☺Ask the patient to void just before the test to minimize the risk of puncturing the bladder After: ☺Instruct the px to immediately report abdominal pain or cramping, chills, fever, vaginal bleeding or leakage of serous vaginal fluid, or fetal hyperactivity or unusual fetal lethargy before she is discharged.

☺Normal amniotic fluid is clear but may contain white flecks of vernix caseosa when the fetus is near term.

Chorionic Villi Sampling

☺Prenatal test for quick ☺To analyze detection of fetal abnormalities. chromosomal and biochemical disorders. ☺Performed during the 1st trimester. ☺Fingerlike projections that surround the embryonic

for

fetal Before: ☺No abnormalities ☺Explain to the patient that found. samples are best obtained between the 8th and 10th weeks of pregnancy. During: ☺Assist the patient into the lithotomy position.

are

membrane and eventually gives rise to the placenta.

After: ☺Monitor the patient closely for adverse effects.

Contraction Stress Test

☺Measures fetal heart rate ☺To measure fetal heart rate in response to uterine in response to contractions. contractions. ☺Usually, the heart rate of a healthy fetus won’t slow down when contractions begin and after they end. ☺Generally occurs weekly under delivery.

☺Normal results occur when 3 contractions occur in a 10-minute period with no slowing (or late decelerations) of the fetal heart rate in response to contractions.

Estrogen (Serum estrone, estradiol, and estriol)

☺In relation to the fetus, it is ☺To determine secreted by ovarian follicular being cells during the first half of the menstrual cycle and by the corpus luteum during the

☺In pregnant women, estriol level is 2 nanograms/ml (SI, 7 nmol/L) by 30 weeks’ gestation to 30

fetal

Before: ☺Explain testing procedure to the patient. ☺explain that the test generally lasts for 30 to 40 minutes. During: ☺After the patient lies down, place two belts around the abdomen with transducers positioned over the fetal heartbeat and over the uterus for contractions. ☺Connect the belts to an external fetal monitor. ☺Record the fetal heart rate and contractions on the monitor and on a paper printout. ☺If the patient isn’t having contractions, ask her to stimulate one of her nipples for a brief time, until contractions begin. After: ☺Monitor the patient closely. well- ☺Tell the patient that she need not restrict food and fluids. ☺Tell the patient that the test requires a blood sample.

luteal phase pregnancy.

Human placental lactogen

and

during

☺A polypeptide hormone also known as human chorionic somatomammotropin that displays lactogenic and somatotropic (growth hormone) properties in a pregnant woman. ☺In combination with prolactin, hPL prepares breast for lactation. ☺Indirectly provides energy for maternal metabolism and fetal nutrition. ☺Facilitates protein synthesis and mobilization essential to fetal growth. ☺Secretion is autonomous, beginning at about 5 weeks’ gestation and declining rapidly after delivery. ☺This radioimmunoassay measures plasma hPL levels,

To assess placental function and fetal well-being. ☺To aid diagnosis of hydatidiform mole and choriocarcinoma. ☺To aid in the diagnosis and monitor treatment of nontrophoblastic tumors that ectopically secrete hPL.

Explain who will perform the venipuncture and when. ☺Explain to the patient that she may experience slight discomfort from the tourniquet and needle puncture. ☺Apply direct pressure to the venipuncture sight until bleeding stops. ☺Instruct the patient that she may resume medications stopped before the test. ☺Explain to the patient that this test helps assess placental functions and fetal well-being. ☺If assessing fetal well-being isn’t the diagnostic objective, offer an appropriate explanation. ☺Explain to the patient that she may experience slight discomfort from the tourniquet and the needle puncture. ☺Inform the pregnant patient that it may be necessary to repeat this test during her pregnancy. ☺Apply direct pressure to the venipuncture until bleeding stops.

nanograms/ml (SI, nmol/L) by week 40.

105

☺For pregnant women, normal hPL levels vary with gestational phase and slowly increase throughout pregnancy, reaching8.6 µ/ml at term is normal. ☺5-27µweeks:<4.6 µ/ml ☺28-31weeks: 2.4-6.1µg/ml ☺32-35 weeks to term: 5.08.6gµ/ml ☺At term, patients with diabetes may have mean levels of 9-11µg/ml ☺Normal levels for men and nonpregnant women are less than 0.5µg/ml

which are roughly proportional to placental mass. ☺Assays must be necessary in high-risk pregnancies and suspected placental tissue dysfunction. ☺Because values vary widely during the latter half of pregnancy, serial determinations over several days provide the most reliable test results. ☺Combined with the measurement of estriol levels, this is a reliable indicator of placental function and fetal well-being. ☺Also useful as a tumor marker in certain malignant states such as ectopic tumors that secrete hPL. Fetal-maternal erythrocyte distribution

☺Measures the number of fetal RBCs in the maternal circulation. ☺Some transfer of RBCs fromt\ the fetal to the maternal circulation occurs during most spontaneous or electrive abortions and most normal deliveries. ☺Usually, the amount of blood transferred is minimal and has no clinical

☺To detect and measure fetal-maternal blood transfer ☺To determine the amount of Rh0(D) immune globulin needed to prevent maternal immunization to the antigen.

☺Explain to the patient that ☺Maternal whole blood this test determines the contains no fetal RBCs amount of fetal blood transferred to the maternal circulation and helps determine the appropriate treatment, if necessary. ☺Inform the patient that the she need not to restrict food and fluids. ☺Tell the patient that the test requires a blood sample.

significance. ☺Transfer of significant amounts of blood from an Rh-positive fetus to an Rhnegative mother can result in maternal immunization to the D antigen and the development of anti-D antibodies in the maternal circulation. ☺During a subsequent pregnancy, the maternal immunization subjects an Rh-positive fetus to potentially fatal hemolysis and erythroblastosis. Internal Fetal Monitoring

Invasive procedure that involves attaching an electrode to the fetal heart rate (FHR). A catheter introduced into the uterine cavity measures the frequency and pressure of uterine contraction. Performed only during labor, after the membranes have ruptured and the cervix has dilated 3 cm, with the fetal head lower than the -2 station and only if external monitoring provides inadequate data.

Explain who will perform the venipuncture and when. ☺Explain to the patient that she may experience slight discomfort from the tourniquet and needle puncture. ☺Check the patient’s history for recent administration of dextran, IV contrast media, or drugs that may alter the results. ☺Apply direct pressure to the venipuncture site until bleeding stops.

To monitor FHR, especially beat-to-beat variability (shortterm variability). To measure the frequency and pressure of uterine contraction to assess the progress of labor. To evaluate intrapartum fetal health. To supplementary or replace external fetal monitoring.

Before: Explain to the patient that internal fetal monitoring accurately assesses fetal health and uterine activity and that it doesn’t necessarily mean there’s a problem. Warn the patient that she may feel mild discomfort when the uterine catheter and scalp electrode are inserted. Make sure the patient or a responsible family member has signed an informed

120 to 160 beats/minute, with a variability of 5 to 25 beats/minute.

consent. Provides more accurate information about fetal health than external monitoring and is especially useful in determining whether cesarean delivery is necessary. Carries minimal risks to the patient (perforated uterus and intrauterine infection) and fetus (scalp abscess and hematoma).

During: For the Fetal heart rate Assist the patient into the dorsal lithotomy position and prepare her perineal area for a vagina examination, explaining each step of the procedure as it’s perform by the physician or certified nurse-midwife. As the procedure begins ask the patient to breath to her mouth and relax her abdominal muscle. After the vaginal examination, the fetal scalp is palpated and an appropriate site is identified. A plastic tube carrying a small electrode is introduced into the cervix, press firmly against the fetal scalp, and rotated clockwise to attached the electrode to the scalp. For uterine contraction Before the uterine catheter is inserted fill it with sterile normal saline solution to prevent air emboli. Explain

each step of the procedure to the patient. As the patient breathe deeply to her mouth and to relax her abdominal muscle. After the vagina has been examine and the presenting part of the fetus palpated, the catheter and guide are inserted 3/8” to ¾” (1 to 2 cm) into the cervix, usually between the fetal head and the posterior cervix After: After removing the fetal scalp electrode, apply antiseptic or antibiotic solution to the attachment site

Ultrasonography Pelvis

Transmit high frequency sound wave into the interior pelvic region, resultant echoes are converted to electrical impulses, amplified by a transducer, and displayed on a monitor. A-mode technique records

To detect foreign bodies and distinguished between cysts and solid masses or tumor.

Make sure to remove the fetal scalp electrode and the uterine catheter before cesarean delivery. Before: Make sure the patient has sign an appropriate consent form.

To measure organ size. To evaluate the fetal viability, position, gestational age, and growth rate.

Note and report any allergies. Instruct the patient to drink

The uterus is normal in size and shape. The ovaries are normal in size, shape and sonographic density. The bodies of the uterus lies on the superior surface

only distances between interfaces. B-mode (brightness modulation) technique creates a to-dimensional image.

To detect multiple pregnancy To confirm fetal abnormalities To confirm maternal abnormalities

fluid and avoid urination before the test because the pelvic ultasonography requires a full bladder as a landmark to define pelvic organ. Explain that the test won’t harm the fetus.

Gray-scale technique represents organ texture in shades of gray on a screen.

During: With the patient in a supine position, coat the lower abdomen with mineral oil or water soluble jelly to increase sound wave conduction.

Real-time imaging creates instant images of the tissues in motion, similar to fluoroscopic examination. Selected views may be photographed for later examination and kept as a permanent record of the test.

The transducer crystal is guided over the area, images are observed on the oscilloscope screen and good images are photographed.

Often used to evaluate symptoms that suggest pelvic disease, to confirm a tentative diagnosis, and to determine fetal growth during pregnancy.

of the bladder, the uterine tube are attached laterally. The ovaries are located on the lateral pelvic wall. With the external iliac vessel above and the urethers posteroinferior, and are covered by the fimbria of the uterine tubes medially. No other masses are visible. If the patient is pregnant the gestational sac and fetus are normal size per date, the placenta is located in the fundus of the uterus

After: Allow the patient to empty her bladder immediately after the test. Remove ultrasound gel from the patients’ skin.

External Fetal Monitoring

Electronic transducer and a cardio tachometer amplify and record fetal heart rates while a pressure – sensitive

To measure FHR and frequency of the uterine contraction.

Before: Explain to the patient that external fetal monitoring assesses fetal health.

Nonstress test: A normal, healthy fetus usually has 3 rises in FHR within 15 minutes, but

transducer record uterine contraction. Record the baseline FHR, periodic fluctuation in the baseline FHR, and beat to beat heart rate viability. Also used during other test of fetal health, notably the non stress test and the contraction stress test

To evaluate antepartum and intrapartum fetal health during stress and non stress situation To detect fetal distress. To determined the necessity for internal fetal monitoring.

Explain the procedure to the patient and answer all her question. Assure her that external fetal monitoring id painless and won’t hurt the fetus or interfere with normal labor. If monitoring will occur antepartum, instruct the patient to eat a meal just before the stress to increase fetal activity, which decreases the test time. If the patient is still smoking advised her to abstain for 2 hours before testing because smoking decrease fetal activity. Explain to the patient that she may have t restrict movement during this line reading but that she may change position between the readings. During: For antepartum monitoring with nonstress test tell the patient to hold the pressure transducer in her hand and to put it each time she feels the fetus move.

fetuses may sleep up to 45 minutes at a time. If there’s no change in FHR in a 10 minute period, consider shaking the patient abdomen gently, clapping loudly, or having the patient drink ice water or apple juice. If the FHR remain unchanged a contraction stress test should be ordered. The fetus is assesses by watching fetal movement muscle tone, fetal breathing, and the amniotic fluid index. CST: The fetus is assumed to be healthy and should remain so for another week if 3 contraction occur during a 10 minute period, with no late deceleration.

Within a 20 minute period. Monitor baseline FHR until you record 2 fetal movements that last longer than 15 seconds each and cause heart rate acceleration of more than 15 beats per minute from the baseline. If you can’t obtain 2 FHR acceleration. Within 30 minutes, gently shake the patient abdomen to stimulate the fetus and repeat the test. For antepartum monitoring test with a CST induce contraction by oxytocin infusion or nipple stimulation. When using nipple stimulation tell the patent to stimulate 1 nipple by hand until contraction begins. If a second contraction doesn’t occur in 2 minutes, have her stimulate the nipple again. Stimulate both nipple if contraction don’t occur in 15 minutes. Continue the test until contractions occur in 10 minutes. After: Answer the patients question about the test.

Fetal hemoglobin

Fetal hemoglobin (HbF) is a normal hemoglobin produced in the red blood cells of a fetus and in smaller amounts in infants. Constitutes 50% -90% of the hemoglobin level in a neonate; the remaining hemoglobin level consists of HbA1 and HbA2 (the hemoglobin level in adults) Normally, the body stops making HbF during the firsts years of life and begins to make HbA. If change-over doesn’t occur and HbF continues to constitute more than 5% of the hemoglobin level after age 6 months, an abnormality maybe present, particularly thalassemia.

To diagnose thalassemia

Before: Explain to the patient that the tests detects thalassemia disease Tell the patient that the test requires a blood sample. Explain who will perform the venipuncture and when. Reassure the patient that drawing the sample will take less than 3 minutes. Explain to the patient that he may feel slight discomfort from the tourniquet and needle puncture. If the patient is a child explain to his parents that a small amount of blood will be taken from his finger or earlobe. Inform the patient or his parents that he need not restrict food and fluids. During: Perform a venipuncture and

In neonates up to age 1 month: 60% -90% (SI, 0.60-0.90). In children ages 1-23 months: 2% (SI, 0.02). From age 24 months to adult: 0%-2% (SI, 0-0.02).

collect the sample of blood in a 4.5 ml ethylenediaminetetraacetic acid tube. Completely fill the collection ube and invert it gently several times to mixed the sample and the anticoagulant thoroughly. Handle the sample gently to prevent hemolysis. After: Apply direct pressure to the venipuncture site until bleeding stops. Ensure the subdermal bleeding has stopped before removing pressure.

Human chorionic gonadotropin, urine

Qualitative analysis of urine levels of human chorionic gonadotropin (small age CG) detects pregnancy as early as 14 days after ovulation. Production of hCG, a glycoprotein that prevents the generations of the corpus

To detect and confirm pregnancy. To aid in the diagnosis of hydatidiform mole or hCGsecreting tumors, threatened abortion, or dead fetus.

If hematoma at the venipuncture site is large, monitor pulses distal to the site. Before: If appropriate explain to the patient that the urine hCG test determines whether she’s pregnant or determined the status of her pregnancy. Alternatively, explain how the test functions as a screen

In a qualitative immunoassay analysis, results are negative (nonpregnant) or positive (pregnant) for hCG. In quantitative analysis urine hCG levels in the first trimester of a normal

luteum at the end of a normal menstrual cycle, begins after conception During the first trimester, hCG levels rise steadily and rapidly, peaking around 10 weeks gestation, subsequently tapering off to less than 10% of peak levels. Most common method of evaluating hCG in urine is hemagglutination inhibition. Provides qualitative and quantitative information. Qualitative urine test is easier and less expensive than the serum hCG test (beta-subunit assay); therefore, it’s a more common test for detecting pregnancy.

for some types of cancer. Tell the patient she need not restrict food but should restrict fluids for 8 hours before the test. Inform the patient that the test require a first-voided morning specimen or urine collection over a 24-hour period, depending on whether the test is qualitative or quantitative. Notify the laboratory and physician of drugs the patient is taking that may affect test results; it may be necessary to restrict them. During: For verification of pregnancy (qualitative analysis), collect a first voided morning specimen. If this isn’t possible, collect a random specimen. For quantitative analysis of hCG, collect the patients urine over a 24-hour period in the appropriate container, discarding the first specimen and retaining the last.

pregnancy maybe as high as 500,000 IU/24 hours; and in the second trimester, from 10,00025,000 IU/24 hours; and in the third trimester from 5,000-15,000IU for 24 hours. Measurable hCG levels don’t normally appear in the urine of men or non pregnant woman.

Specify the date of the patients last menstrual period on the laboratory request. Refrigerate the 24-hour specimen or keep it on ice during the collection period. Be sure the test occurs atleast 5 days after a missed period to avoid a falsenegative result.

Transvaginal ultrasound

Imaging technique using high frequency sound waves to produce images of the pelvic structures.

To established early pregnancy with fetal heart motion as early as the 5th to 6th week of gestation.

After: Instruct the patient that she may resume her usual diet and medication. Before: Make sure the patient has signed an appropriate consent form.

Allows evaluation of pelvic anatomy and diagnosis of pregnancy at an earlier gestational age.

To identify ectopic pregnancy.

Note and report all allergies.

To monitor follicular growth during infertility treatment.

Eliminates the need for a full bladder and circumvents difficulties encounter with obese patients.

To evaluate abnormal pregnancy.

Explain to the patient that the test requires insertion of a vaginal probe and the self insertion may be possible.

Also known as endovaginal ultrasound

To visualize retained products of conception. To diagnose fetal abnormalities, placental

If the sonographer is a man, assure the patient that a female assistant will be present during the examination.

The uterus and ovaries are normal in size and shape . The body of the uterus lies on the superior surface of the bladder; the uterine tubes are attached laterally The ovaries are located on the lteral pelvic walls with external iliac vessels above and the urether posteroinferior, and are covered by the fimbria of the uterine tubes medially. In pregnancy, the gestational sac and fetus

location, and cervical length. To evaluate adnexal pathology, such as tuboovarian abscess, hydrosalpinx, and ovarian masses. To evaluate the uterine lining

During: Assist the patient into the lithotomy position. Water-soluble gel is place on the transducer tip to allow better sound transmission, and a protective sheath is place over the transducer. Additional lubricant is place on the sheathed transducer tip, which is gently inserted into the vagina by the patient or the sonographer. The pelvic structures are observe by rotating the probe 90 degrees to one side and then the other. After: Help the patient remove any residual gel

References: Pillitteri, Adele (2007).Maternal & Child Health Nursing, Fifth edition McKinney, Emily Slone (2000). Maternal-Child Nursing,First edition http://www.fetalscreening.com/diagnostic_test.php

are of normal size for the gestational period.