ASSESSMENT OF FETAL GROWTH AND DEVELOPMENT

McDonald’s rule,

a symphysis-fundal height measurement, although not documented to be thoroughly reliable, is an easy method of determining during midpregnancy that a fetus is growing in utero.

Typically, the distance from the uterine fundus to the symphysis pubis in centimeters is equal to the week of gestation between the 20th and 31st weeks of pregnancy. Make the measurement from the notch of the symphysis pubis to over the top of the uterine fundus as a woman lies supine

12 Weeks

Fundus is just palpable above the Symphysis Pubis.

16 Weeks

Midway between Symphysis Pubis and Umbilicus.

20 Weeks

At the level of the Umbilicus (measures ~20 cm).

36 Weeks

At the level of the Xiphoid Process (highest point).

40 Week

Fundus drops slightly (34–36 cm) due to Lightening (fetal head drops into pelvis).

Multiple gestation, Polyhydramnios, Macrosomia, Molar pregnancy (Hydatidiform Mole), Uterine fibroids

Fundus HIGHER than expected AOG

Intrauterine Growth Restriction (IUGR), Oligohydramnios, Fetal demise, Incorrect LMP calculation

Fundus LOWER than expected AOG

18 to 20 weeks

Fetal movement that can be felt by the mother (quickening) occurs at approximately_________ of pregnancy and peaks in intensity at 28 to 38 weeks.

10

A healthy fetus moves with a degree of consistency, or at least ____ times a day.

120 to 160 beats per minute,

Fetal hearts beat at ________ throughout pregnancy.

10th to 11th week

Fetal heart sounds can be heard and counted as early as the __________ of pregnancy by the use of an ultrasonic Doppler technique

Rhythm Strip Testing

means assessment of the fetal heart rate for whether a good baseline rate and a degree of variability are present.

For this, help a woman into a semi-Fowler’s position (either in a comfortable lounge chair or on an examining table or bed with an elevated backrest) to prevent her uterus from compressing the vena cava and causing supine hypotension syndrome during the test.

It is categorized as absent (none apparent); minimal (extremely small fluctuations); moderate (amplitude range of 6–25 beats per minute); and marked (amplitude range over 25 beats per minute)

Variability

refers to small changes in rate that occur if the fetal parasympathetic and sympathetic nervous systems are receiving adequate oxygen and nutrients.

nonstress test

measures the response of the fetal heart rate to fetal movement. Position a woman and attach both a fetal heart rate and a uterine contraction monitor.

reactive

if two accelerations of fetal heart rate (by 15 beats or more) lasting for 15 seconds occur after movement within the chosen time period.

nonreactive

The test is _______ if no accelerations occur with the fetal movements.

Vibroacoustic Stimulation

For acoustic (sound) stimulation, a specially designed acoustic stimulator is applied to the mother’s abdomen to produce a sharp sound of approximately 80 decibels at a frequency of 80 Hz, startling and waking the fetus

Contraction Stress Testing

the fetal heart rate is analyzed in conjunction with contractions. When this test was first developed, contractions were initiated by the intravenous infusion of oxytocin.

The test is negative (normal) if no fetal heart rate decelerations are present with contractions. It is positive (abnormal) if 50% or more of contractions cause a late deceleration (a dip in fetal heart rate that occurs toward the end of a contraction and continues after the contraction)

Ultrasonography

which measures the response of sound waves against solid objects

It can be used to:

• Diagnose pregnancy as early as 6 weeks’ gestation

• Confirm the presence, size, and location of the placenta and amniotic fluid

• Establish that a fetus is growing and has no gross anomalies, such as hydrocephalus, anencephaly, or spinal cord, heart, kidney, and bladder defects

• Establish sex if a penis is revealed

• Establish the presentation and position of the fetus

• Predict maturity by measurement of the biparietal diameter of the head

Biparietal Diameter.

In 80% of pregnancies in which the biparietal diameter of the fetal head is 8.5 cm or greater, it can be predicted that the infant will weigh more than 2500 g (5.5 lb) or is at a fetal age of 40 weeks.

Doppler ultrasonography

measures the velocity at which red blood cells in the uterine and fetal vessels travel. Assessment of the blood flow through uterine blood vessels is helpful to determine the vascular resistance present in women with diabetes or hypertension of pregnancy and whether resultant placental insufficiency is occurring.

Electrocardiography

Fetal ECGs may be recorded as early as the 11th week of pregnancy. The ECG is inaccurate before the 20th week, however, because until this time fetal electrical conduction is so weak that it is easily masked by the mother’s ECG tracing. It is rarely used unless a specific heart anomaly is suspected.

Magnetic resonance imaging (MRI)

also may be used to assess the fetus. Because the technique apparently causes no harmful effects to the fetus or woman (although extensive long-term testing is not yet available), MRI has the potential to replace or complement ultrasonography as a fetal assessment technique (Laifer-Narin et al,, 2007).

It may be most helpful in diagnosing complications such as ectopic pregnancy or trophoblastic disease (see Chapter 21), because later in a pregnancy fetal movement (unless the fetus is sedated) can obscure the findings.

AFP

is a substance produced by the fetal liver that is present in both amniotic fluid and maternal serum. The level is abnormally high in maternal serum (MSAFP) if the fetus has an open spinal or abdominal defect such as spina bifida or omphalocele, because the open defect allows more AFP to enter the mother’s circulation.

Triple screening,

or analysis of three indicators (MSAFP, unconjugated estriol, and hCG), may be performed in place of simple AFP testing to yield even more reliable results. As with the measurement of MSAFP, it requires only a simple venipuncture of the mother.

Chorionic villi sampling (CVS)

is a biopsy and chromosomal analysis of chorionic villi that is done at 10–12 weeks of pregnancy.

Coelocentesis

(transvaginal aspiration of fluid from the extraembryonic cavity) is an alternative method to remove cells for fetal analysis.

Amniocentesis

(from the Greek amnion for “sac” and kentesis for “puncture”) is the aspiration of amniotic fluid from the pregnant uterus for examination. The procedure can be done in a physician’s office or in an ambulatory clinic.

It is typically scheduled between the 14th and 16th weeks of pregnancy to allow for a generous amount of amniotic fluid to be present. The technique can be used again near term to test for fetal maturity.

Percutaneous Umbilical Blood Sampling

is the aspiration of blood from the umbilical vein for analysis. After the umbilical cord is located by ultrasound, a thin needle is inserted by amniocentesis technique into the uterus and is guided by ultrasound until it pierces the umbilical vein.

Amnioscopy

is the visual inspection of the amniotic fluid through the cervix and membranes with an amnioscope (a small fetoscope). The main use of the technique is to detect meconium staining. It carries some risk of membrane rupture.

Fetoscopy,

The earliest time in pregnancy that fetoscopy can be performed is about the 16th or 17th week.

in which the fetus is visualized by inspection through a fetoscope (an extremely narrow, hollow tube inserted by amniocentesis technique), can be helpful to assess fetal well-being (Lopriore et al., 2007). If a photograph is taken through the fetoscope, it can document a problem or reassure parents that their infant is perfectly formed.

The procedure is used to:

• Confirm the intactness of the spinal column

• Obtain biopsy samples of fetal tissue and fetal blood samples

• Perform elemental surgery, such as inserting a polyethylene shunt into the fetal ventricles to relieve hydrocephalus or anteriorly into the fetal bladder to relieve a stenosed urethra

Fetal breathing

Fetal movement

Fetal tone

Amniotic fluid volume

Fetal heart reactivity

Biophysical Profile Scoring

Biophysical Profile Scoring

may be done as often as daily during a high-risk pregnancy. If the fetus score on a complete profile is 8–10, the fetus is considered to be doing well. A score of 6 is considered suspicious; a score of 4 denotes a fetus probably in jeopardy.

1st Maneuver (Fundal Grip)

2nd Maneuver (Umbilical/Lateral Grip)

3rd Maneuver (Pawlik's Grip)

4th Maneuver (Pelvic Grip)

Leopold's Maneuvers

1st Maneuver (Fundal Grip):

Determines what occupies the fundus (Head = hard/round/globular; Buttocks/Breech = soft/irregular).

2nd Maneuver (Umbilical/Lateral Grip):

Determines location of fetal back (smooth/firm surface) and small parts/extremities. Fetal heart rate best heard over fetal back.

3rd Maneuver (Pawlik's Grip):

Confirms presentation and whether engagement has occurred in pelvic inlet

4th Maneuver (Pelvic Grip):

Determines fetal attitude and degree of cephalic prominence. (Examiner faces patient's feet).