improve fetal oxygenation (eg, change maternal position, administer oxygen and intravenous fluids, consider amnioinfusion or tocolysis)

3.If the nonreassuring pattern does not resolve within a few minutes, perform ancillary tests to determine the fetal condition

4.Determine whether operative intervention is needed

B.The presence of accelerations almost always assures the absence of fetal acidosis. Therefore, if such accelerations are not observed, they should be elicited by manual or vibroacoustic stimulation. There is a 50 percent risk of fetal acidosis in fetuses in whom accelerations cannot be elicited, so further evaluation by fetal scalp sampling for pH is indicated to help clarify the fetal acid-base status. Serial evaluation every 20 to 30 minutes is necessary if the FHR pattern remains nonreassuring. Expeditious delivery is indicated for persistent nonreassuring FHR patterns.

Management of Variant Fetal Heart Rate Patterns

References: See page 155.

Antepartum Fetal Surveillance

I.Antepartum fetal surveillance techniques

A.Antepartum fetal surveillance should be initiated in pregnancies in which the risk of fetal demise is known to be increased. These problems can include maternal conditions such as antiphospholipid syndrome, chronic hypertension, renal disease, systemic lupus erythematosus, or type 1 diabetes mellitus. Monitoring should also be initiated in pregnancy-related conditions such as preeclampsia, intrauterine growth restriction (IUGR), multiple gestation, poor obstetrical history, or postterm pregnancy.

B.Antepartum fetal surveillance can include the nonstress test (NST), BPP, oxytocin challenge test (OCT), or modified BPP.

C.Nonstress test

1.A NST is performed using an electronic fetal monitor. Testing is generally begun at 32 to 34 weeks. Testing is performed at daily to weekly intervals as long as the indication for testing persists.

2.The test is reactive if there are two or more fetal heart rate accelerations of 15 bpm above the baseline rate lasting for 15 seconds in a 20 minute period. A nonreactive NST does not show such accelerations over a 40 minute period. Nonreactivity may be related to fetal immaturity, a sleep cycle, drugs, fetal anomalies, or fetal hypoxemia.

3.If the NST is nonreactive, it is considered nonreassuring and further evaluation or delivery of the fetus is indicated. At term, delivery rather than further evaluation is usually warranted. A nonreassuring NST preterm usually should be assessed with ancillary tests, since the false positive rate of an isolated NST may be 50 to 60 percent.

D.Fetal movement assessment (“kick counts”)

1.A diminution in the maternal perception of fetal movement often but not invariably precedes fetal death, in some cases by several days.

2.The woman lies on her side and counts distinct fetal movements. Perception of 10 distinct movements in a period of up to 2 hours is considered reassuring. Once 10 movements have been perceived, the count may be discontinued. In the absence of a reassuring count, non stress testing is recommended.

Indications for Antepartum Fetal Surveillance

E.Ancillary tests

1.Vibroacoustic stimulation is performed by placing an artificial larynx on the maternal abdomen and delivering

ashort burst of sound to the fetus. The procedure can shorten the duration of time needed to produce reactivity and the frequency of nonreactive NSTs, without compromising the predictive value of a reactive NST.

2.Oxytocin challenge test

a.The oxytocin challenge test (OCT) is done by intravenously infusing dilute oxytocin until three contractions occur within ten minutes. The test is interpreted as follows:

b.A positive test is defined by the presence of late decelerations following 50 percent or more of the contractions

c.A negative test has no late or significant variable decelerations

d.An equivocal-suspicious pattern consists of intermittent late or significant variable decelerations, while an equivocal-hyperstimulatory pattern refers to fetal heart rate decelerations occurring with contractions more frequent than every two minutes or lasting longer than 90 seconds

e.An unsatisfactory test is one in which the tracing is uninterpretable or contractions are fewer than three in 10 minutes

f.A positive test indicates decreased fetal reserve and correlates with a 20 to 40 percent incidence of abnormal FHR patterns during labor. An equivocal-suspi- cious test with repetitive variable decelerations is also associated with abnormal FHR patterns in labor, which are often related to cord compression due to oligohydramnios.

3.Fetal biophysical profile

a.The fetal biophysical profile score refers to the sonographic assessment of four biophysical variables: fetal movement, fetal tone, fetal breathing, amniotic fluid volume and nonstress testing. Each of these five parameters is given a score of 0 or 2 points, depending upon whether specific criteria are met. Fetal BPS is a noninvasive, highly accurate means for predicting the presence of fetal asphyxia.

b.Criteria

(1)A normal variable is assigned a score of two and an abnormal variable a score of zero. The maximal score is 10/10 and the minimal score is 0/10.

(2)Amniotic fluid volume is based upon an ultrasound-based objective measurement of the largest visible pocket. The selected largest pocket must have a transverse diameter of at least one centimeter.

Components of the Biophysical Profile

A total score of 8 to 10 is reassuring; a score of 6 is suspicious, and a score of 4 or less is ominous.

Amniotic fluid index = the sum of the largest vertical pocket in each of four quadrants on the maternal abdomen intersecting at the umbilicus.

c.Clinical utility

(1)The fetal BPS is noninvasive and highly accurate for predicting the presence of fetal asphyxia. The probability of fetal acidemia is virtually zero when the score is normal (8 to 10). The false negative rate (ie, fetal death within one week of a last test with a normal score) is exceedingly low. The likelihood of fetal compromise and death rises as the score falls.

(2)The risk of fetal demise within one week of a normal test result is 0.8 per 1000 women tested. The positive predictive value of the BPS for evidence

of true fetal compromise is only 50 percent, with a negative predictive value greater than 99.9 percent.

d.Indications and frequency of testing

(1)ACOG recommends antepartum testing in the following situations:

(a)Women with high-risk factors for fetal asphyxia should undergo antepartum fetal surveillance with tests (eg, BPS, nonstress test)

(b)Testing may be initiated as early as 26 weeks of gestation when clinical conditions suggest early fetal compromise is likely. Initiating testing at 32 to 34 weeks of gestation is appropriate for most pregnancies at increased risk of stillbirth.

(c)A reassuring test (eg, BPS of 8 to 10) should be repeated periodically (weekly or twice weekly) until delivery when the high-risk condition persists.

(d)Any significant deterioration in the clinical status (eg, worsening preeclampsia, decreased fetal activity) requires fetal reevaluation.

(e)Severe oligohydramnios (no vertical pocket >2 cm or amniotic fluid index <5) requires either delivery or close maternal and fetal surveillance.

(f)Induction of labor may be attempted with abnormal antepartum testing as long as the fetal heart rate and contractions are monitored continuously and are reassuring. Cesarean delivery is indicated if there are repetitive late decelerations.

(2)The minimum gestational age for testing should reflect the lower limit that intervention with delivery would be considered. This age is now 24 to 25 weeks.

(3)Modified biophysical profile. Assessment of amniotic fluid volume and nonstress testing appear to be as reliable a predictor of long-term fetal well-being as the full BPS. The rate of stillbirth within one week of a normal modified BPS is the same as with the full BPS, 0.8 per 1000 women tested.

Guidelines for Antepartum Testing

F.Perinatal outcome. An abnormal NST result should be interpreted with caution. Further assessment of fetal condition using the NST, OCT, or BPP should usually be performed to help determine whether the fetus is in immediate jeopardy.

G.Management of abnormal test results

1.Maternal reports of decreased fetal movement should be evaluated by an NST, CST, BPP, or modified BPP. These results, if normal, usually are sufficient to exclude imminent fetal jeopardy. A nonreactive NST or an abnormal modified BPP generally should be followed by additional testing (either a CST or a full BPP). In many circumstances, a positive CST result generally indicates that delivery is warranted.

2.A BPP score of 6 is considered equivocal; in the term fetus, this score generally should prompt delivery, whereas in the preterm fetus, it should result in a repeat

BPP in 24 hours. In the interim, maternal corticosteroid administration should be considered for pregnancies of less than 34 weeks of gestation. Repeat equivocal scores should result either in delivery or continued intensive surveillance. A BPP score of 4 usually indicates that delivery is warranted.

3.Preterm delivery is indicated for nonreassuring antepartum fetal testing results that have been confirmed by additional testing. At term, additional testing can be omitted since the risk from delivery is small. Depending on the fetal heart rate pattern, induction of labor with continuous FHR and contraction monitoring may be attempted in the absence of obstetrical contraindications. Repetitive late decelerations or severe variable decelera-

tions usually require cesarean delivery.

References: See page 155.

Brief Postoperative Cesarean Section

Note

Pre-op diagnosis:

1.23 year old G1P0, estimated gestational age = 40 weeks

2.Dystocia

3.Non-reassuring fetal tracing

Post-op diagnosis: Same as above

Procedure: Primary low segment transverse cesarean section

Attending Surgeon, Assistant: Anesthesia: Epidural

Operative Findings: Weight and sex of infant, APGARs at 1 min and 5 min; normal uterus, tubes, ovaries.

Cord pH:

Specimens: Placenta, cord blood (type and Rh). Estimated Blood Loss: 800 cc; no blood replaced.

Fluids, blood and urine output: Drains: Foley to gravity.

Complications: None

Disposition: Patient sent to recovery room in stable condition.

Cesarean Section Operative Report

Preoperative Diagnosis:

1.23 year old G1P0, estimated gestational age = 40 weeks

2.Dystocia

3.Non-reassuring fetal tracing

Postoperative Diagnosis: Same as above

Title of Operation: Primary low segment transverse cesarean section

Surgeon:

Assistant: Anesthesia: Epidural

Findings At Surgery: Male infant in occiput posterior presentation. Thin meconium with none below the cords, pediatrics present at delivery, APGAR's 6/8, weight 3980 g. Normal uterus, tubes, and ovaries.

Description of Operative Procedure:

After assuring informed consent, the patient was taken to the operating room and spinal anesthesia was initiated. The patient was placed in the dorsal, supine position with left lateral tilt. The abdomen was prepped and draped in sterile fashion.

A Pfannenstiel skin incision was made with a scalpel and carried through to the level of the fascia. The fascial incision was extended bilaterally with Mayo scissors. The fascial incision was then grasped with the Kocher clamps, elevated, and sharply and bluntly dissected superiorly and inferiorly from the rectus muscles.

The rectus muscles were then separated in the midline, and the peritoneum was tented up, and entered sharply with Metzenbaum scissors. The peritoneal incision was extended superiorly and inferiorly with good visualization of the bladder.

A bladder blade was then inserted, and the vesicouterine peritoneum was identified, grasped with the pick-ups, and entered sharply with the Metzenbaum scissors. This incision was then extended laterally, and a bladder flap was created. The bladder was retracted using the bladder blade. The lower uterine segment was incised in a transverse fashion with the scalpel, then extended bilaterally with bandage scissors. The bladder blade was removed, and the infants head was delivered atraumatically. The nose and mouth were suctioned and the cord clamped and cut. The infant was handed off to the pediatrician. Cord gases and cord blood were sent.

The placenta was then removed manually, and the uterus was exteriorized, and cleared of all clots and debris. The uterine incision was repaired with 1-O chromic in a running locking fashion. A second layer of 1-O chromic was used to obtain excellent hemostasis. The bladder flap was repaired with a 3-O Vicryl in a running fashion. The cul-de-sac was cleared of clots and the uterus was returned to the abdomen. The peritoneum was closed with 3-0 Vicryl. The fascia was reapproximated with O Vicryl in a running fashion. The skin was closed with staples.

The patient tolerated the procedure well. Needle and sponge counts were correct times two. Two grams of Ancef was given at cord clamp, and a sterile dressing was placed over the incision.

Estimated Blood Loss (EBL): 800 cc; no blood replaced (normal blood loss is 500-1000 cc).

Specimens: Placenta, cord pH, cord blood specimens. Drains: Foley to gravity.

Fluids: Input - 2000 cc LR; Output - 300 cc clear urine.

Complications: None.

Disposition: The patient was taken to the recovery room then postpartum ward in stable condition.