and a history of premature labor.

Preparation

1. Obtain an aminocentesis tray, surgical scrub solution,

a light-protected container, and povidone-iodine

solution. Also, obtain RhoGAM for Rh-negative

mothers.

2. Obtain maternal vital signs. Auscultate baseline fetal

heart tones.

3. Note the estimated date of conception and week of

gestation on the laboratory requisition.

4. Procedure should be performed in a darkened room

if the specimen will be tested for bilirubin.

5. See patient and family teaching.

396 Concise Book of Medical Laboratory Technology: Methods and Interpretations Procedure

1. The position of the fetus and a pocket of amniotic fluid

are determined using ultrasound and palpation, with

the mother in a supine position.

2. The mother’s abdominal area is cleansed with surgical

scrub solution and povidone-iodine and allowed to

dry.

3. The aspiration site is draped, demarcating a sterile

field.

4. The mother is instructed to place her hands behind her

head, and the aspiration site is anesthetized with 1 mL

of 1 or 2% lidocaine intradermally and subcutaneously.

5. A 20 to 22-gauge, 5-inch-long spinal needle with a

stylette is inserted through the abdominal wall into

the intrauterine cavity, and the stylette is withdrawn.

6. About 10–15 mL of amniotic fluid is aspirated through

the spinal needle into a syringe, and the needle is

withdrawn. Use a 20 mL amniotic fluid sample for

direct genetic analysis for the four most common

mutations responsible for Tay-Sachs disease.

Postprocedure Care

1. Apply a dry sterile dressing to the aspiration site.

2. Inject 5 mL of amniotic fluid into a light-protected

(foil-covered or amber) test tube to test for bilirubin.

Inject 10 mL of amniotic fluid into a sterile, siliconized

glass container or a polystyrene container for culture

and genetic and other studies (AFP). Specimens to be

transported to another site for testing should be packed

in a cool, insulated container to maintain a temperature

of 2–5°C. Freezing temperatures should be avoided.

3. Obtain the mother’s vital signs. Auscultate fetal heart

tones for changes from the baseline.

4. The mother should rest on her right side for 15–20

minutes after the procedure.

5. RhoGAM may be prescribed for Rh-negative mothers.

6. Transport the amniotic fluid specimen to the

laboratory immediately and refrigerate.

Patient and Family Teaching

1. Empty your bladder immediately prior to the procedure if gestation is 21 weeks or more. You must have

a full bladder during the procedure if gestations is

20 weeks or less.

2. It is important to lie motionless throughout the

procedure. You may experience a strong contraction

with the needle insertion.

3. Chromosome analysis results may take up to 4 weeks.

4. Inform the patient with abnormal genetic findings of

choices regarding pregnancy and pregnancy termination. Also, refer the patient for genetic counseling

prior to future attempts to become pregnant.

5. After the procedure, notify the physician for cramping,

abdominal pain, unusual vaginal drainage/fluid loss,

fever, chills, dizziness, or more or less than the usual

amount of fetal activity.

Factors that Affect Results

1. Reject frozen or clotted specimens.

2. Inadvertent aspiration of maternal urine can be ruled

out by testing the specimen for blood urea nitrogen

(BUN) and creatinine. Urine BUN is >100 mg/dL,

whereas amniotic fluid is well under 100 mg/dl. Urine

creatinine is usually 0.80 mg/dL, whereas amniotic

fluid creatinine is usually <4 mg/dL.

3. Nonsiliconized glass containers for routine analysis

may result in cell adherence on the sides of the

container.

4. Amniotic fluid testing must be performed within 3 days

of collection.

5. Amniocentesis should be performed between weeks

24 and 28 when checking for hemolytic disease of the

newborn and Rh sensitization.

6. Falsely low bilirubin levels may result from failure to

protect the specimen from light.

7. Specimens contaminated with blood should be tested

for fetal hemoglobin to determine whether the blood is

of maternal or fetal origin. Fetal blood contamination

results in falsely high bilirubin levels. Fetal or maternal

blood will interfere with measurements of fetal lung

maturity and amniotic fluid constituents that are also

constituents of plasma, such as protein, potassium,

and glucose.

8. Creatinine levels are affected by maternal creatinine

clearance and maternal creatinine levels. A concurrent

maternal serum creatinine should be drawn. Maternal

serum to amniotic fluid creatinine should be about 2:1.

9. Elevated AFP results may be caused by contamination

of the specimen with fetal blood.

10. Small and closed neural tube defects may not cause

elevated AFP levels.

11. Accurate L/S ratio measurement is not possible if

the specimen is contaminated with blood (fetal or

maternal) or meconium.

Other Data

1. Direct karyotyping of placental villi samples obtained

by needle aspiration has been found to yield faster

results than amniotic fluid chromosome analysis.

Cerebrospinal and Other Body Fluids 397

2. Chromosomal aberration has been found in 4.6% of

fetuses in women over 38 years old, the most common

being trisomy 21 (62%), Klinefelter’s syndrome (11%),

and Edward’s syndrome {(trisomy 18) (11%)}.

3. For diamniotic twin pregnancies, each amniotic sac

should be sampled.

4. A 1995 study suggested that early amniocentesis

is feasible from 11 weeks of gestation and “can be

performed for the usual indications” as an alternative

to chorionic villus sampling. In the future, results will

be available in less than 1 week using cytogenetic

techniques.

5. Prenatal cystic fibrosis profile may be performed by

polymerase chain reaction.

13

Semen Analysis

C H A P T E R

INTRODUCTION

Semen examination is an integral part of the evaluation of infertility. As a result of its relative simplicity,

semen examination is often requested before the more

complicated and expensive examination of the female.

Repeat examination should be done if once it is found to

be abnormal.

Semen consists of spermatozoa suspended in seminal

plasma. Spermatozoa comprise about 5% of semen

volume (derived from testis). Approximately, 60% of the

semen volume is derived from the seminal vesicles. This

viscid, neutral, or slightly alkaline fluid is often yellow or

even deeply pigmented because of its high flavin content.

Prostate contributes 20% of the volume of semen. This

milky fluid is slightly acidic, with a pH of about 6.5 largely

because of its high content of citric acid. The prostatic

secretion is also rich in proteolytic enzymes and acid

phosphatase. These proteolytic enzymes are believed to be

responsible for the coagulation and liquefaction of semen.

Less than 10–15% of semen volume is contributed by

epididymidis, vasa deferentia, bulbourethral and urethral

glands.

SEMEN ANALYSIS

A semen analysis measures the amount of semen a man

produces and determines the number and quality of

sperm in the semen sample.

A semen analysis is usually one of the first tests done

to help determine whether a man has a problem fathering

a child (infertility). A problem with the semen or sperm

affects more than one-third of the couples who are unable

to have children (infertile).