Fetal Distress

Fetal DistressSong weiwei

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What is fetal distress?

• Fetal distress is the term commonly used to describe fetal hypoxia. It is a clinical diagnosis made by indirect methods and should be defined as:-

Hypoxia that may result in fetal damage or death if not reversed or the fetus delivered immediately.

• More commonly a fetal scalp pH of less than 7.2 is used to indicate distress

Etiology

• Fetal oxygen supplied from:– maternal circulation-----placenta------umbilical

cord------fetus

• maternal factors– cardiovescular diseases– acute bleeding– uterus

Etiology

• Fetal factors– cardiovescular dysfunction– deformity

• umbilical cord and placental factors– abnormal cord:entanglement, nuchal umbilical cord prolapse of cord– abnormal placenta

Causes of Hypoxia*risk factors

Maternal risk factors • Diabetes • Pregnancy-induced or chronic hypertension • Maternal infection • Sickle cell anemia • Chronic substance abuse • Asthma • Seizure disorders • Post-term or multiple-gestation pregnancy

Intrapartum causes of fetal hypoxia**

• Abnormal presentation of the fetus (i.e. breech)

• Premature onset of labor

• Rupture of membrane more than 24 hours prior to delivery

• Prolonged labor

• Administration of narcotics and anesthetics

• Maternal hypoventilation • Maternal hypoxia • Hypotension can be caused by either

epidural anaesthesia or the supine position, which reduces inferior vena cava return of blood to the heart. The decreased blood flow in hypotension can be a cause of fetal distress (supine hypotension syndrome**).

Pathophysiology

• Hypoxia!– Acidosis----sympathetic nerve excited----

• hypertension,

• tachycardia (initial signs)

– profound acidosis-----vagus nerve----• hypotension,

• bradycardia,

• hyperperistalsis----meconium discharge

– chronic condition: • nutritional deficiency----FGR

Clinical manifestation

• Chronic fetal distress– FGR– dysfunction of maternal-placental-fetal unit– fetal heart monitoring– fetal movement calculation– amnioscopy

Clinical manifestation

• Acute fetal distress– fetal heart rate– characteristics of fluid– fetal movement– acidosis

How to define the newborn asphyxia

• Usually with fetal distress.

• Apgar score: 8-10 normal

• 4-7 mild asphyxia

• 0-3 severe asphyxia

Effects of Asphyxia

• Fetal hypoxia is associated with severe complications in all systems. The infant may suffer:

• Hypoxic ischemic encephalopathy • Meconium aspiration syndrome • Acidosis with decompensation • Cerebral palsy • Neonatal seizures

Mecunium

• Normal condition: mature of colon• Fetal hypoxia can stimulate fetal colonic

contraction that leads to evacuation of meconium (fetal stool) into the amniotic fluid

• How meconium is dealt with will depend on what it looks like and what your provider's approach is. Old meconium is yellow and less likely to be a problem .

Meconium

• Thick, green, particulate meconium which may have already caused baby to "gasp" in utero.

• If the meconium is accompanied by decreased heart rates that do not recover well, a c-section will be the safest approach.

• Fetal gasping due to the lack of oxygen which then causes aspiration of the meconium into the lungs.

• The presence of this material can produce bronchial obstruction and a chemical pneumonitis and treatment must be initiated during delivery. If not adequately removed, the meconium blocking the airways can lead to further hypoxia.

•

Meconium aspiration most often occurs in

• Term infants • Growth-retarded infants • Post-term infants • Breech presentation delivery • The degree of meconium aspiration and the length of

exposure to meconium determines the severity of the hypoxia suffered by the fetus. Staining of the umbilical cord, skin, or nails of the infant indicates exposure to meconium 3 to 6 hours in utero prior to delivery.

Assessment**

Antepartum Testing:

Tests for antepartum fetal evaluation include:

• Fetal movement count

• Non stress test

• Contraction stress test

• Biophysical profile

Fetal movement

• Fetal movement counts are performed by the mother and are an inexpensive, noninvasive method of assessing fetal well-being. The patient records the number of times she feels fetal movement within a designated time period. The exact number of normal perceived movements has not been determined, however approximately 10 movements should be felt within a 12 hour period.

Non Stress Test (NST)

• The is an indirect measurement of uteroplacental function and requires specialized equipment and trained personnel.

• This test measures the detection of heart rate accelerations associated with perceived fetal movements.

• A reactive or normal stress test will exhibit at least two accelerations in the fetal heart rate in a 20-minute period.

Contraction Stress Test (CST)

• CST or oxytocin challenge test, is more costly and presents more of a risk to the fetus. but identifies fetal reserve during contractions. The test measures late decelerations during contractions induced by either nipple stimulation or oxytocin infusion. The test is negative if no late decelerations are observed.

Biophysical profile

• fetal movement

• amniotic fluid volume

• respiratory movement

• movement of extremity

• NST

Intrapartum Testing

Tests utilized to assess fetal well being during labor include:

• Intermittent auscultation of the fetal heart rate

• Continuous electronic fetal monitoring

• Scalp pH measurement

• Measurement of the fetal heart rate: abnormal decelerations and decreased variability during contractions are suggestive of fetal distress.

• Intermittent auscultation of the fetal heart rate is a reliable indicator of fetal well being and can be used in low risk deliveries. Routine electronic fetal monitoring is not recommended for low-risk women in labor when adequate clinical monitoring including intermittent auscultation by trained staff is available .

• Continuous intrapartum fetal monitoring is the mainstay in most modern obstetric units. The heart rate of the fetus is monitored to detect increases or decreases during contractions. The variability and trends are interpreted to determine fetal distress or well being.

• Scalp pH measurement helps to determine the presence of acidosis and fetal hypoxia and may influence the decision of whether to continue observation or to perform a cesarean delivery. Neurologic deficits usually occur when there is a severe acidosis, due to hypoxia, present at birth. Severe hypoxia will often cause hypoxic-ischemic encephalopathy in the infant.

What’s the typical signs of fetal distress?**

Typical signs of fetal distress include :

• late heart rate decelerations

• variable decelerations

• prolonged bradycardia

• indications of meconium staining.

• Intrapartum hypoxia is thought to be the leading cause of cerebral palsy and now accounts for 3 to 15% of cerebral palsy cases. Chronic fetal hypoxia, caused by maternal smoking or anemia, may also contribute to a predisposition for Sudden Infant Death Syndrome (SIDS).

Treatment of Hypoxia

Mother’s condition must be treated to prevent hypoxia to the fetus including:

• Blood pressure stabilization

• Maternal positioning on the left side

• Monitoring maternal oxygenation

• Pelvic exam to identify cord presentation

Treatment of Hypoxia• Oxygen administration to the mother may provide

additional availability of oxygen to the fetus. Trained neonatal resuscitation staff should be available at all times and should be present in the delivery suite for those patients with known risk for fetal distress or hypoxia.

• Cesarean sections are performed if all else fails, and are the last alternative when faced with the possibility of fetal distress.

The decision to delivery interval

• Medical litigation is on the rise in our country particularly with relation to obstetrics. The day is not far when premiums for malpractice nsurance rise parallel to the rise in the compensation offered for these cases. Majority of the cases seem to be due to the delay in the decision to delivery interval rather than the problems with diagnosis.


• Although there is poor correlation between FHR patterns and long term outcome a significant association has been noted between the decision to delivery interval and admission to the neonatal intensive care unit for neonatal asphyxia

• An effort must be made to reduce the decision to delivery interval and restrict it to not more than 30 minutes. It should be the norm to keep the women and her relatives apprised of the situation of the labor at all times and involve them in the decision making.


• In some cases of fetal distress immediate operative delivery may be the only option to ensure a healthy neonate. Even in these situations intrauterine resuscitation can play a role in enhancing the perinatal outcome. Ultimately, efficient management and a good outcome in cases of fetal distress reflects a strong infrastructure and good coordination between the obstetrician, the nursing staff, the staff in the operation room and the neonatologist.

Premature rupture of membrane(PROM)

What is premature rupture of membranes?**

• The diagnosis of PROM is made whenever the bag of water ruptures before the onset of true labor.

• PPROM: Preterm premature rupture of membranes is the rupture of membranes during pregnancy before 37 weeks' gestation.

It occurs in 3 percent of pregnancies and is the cause of approximately one third of preterm deliveries.

Incidence

• Varied greatly 2.7%--17%

• PROM is causally related to about 10% perinatal deaths regardless of gestation age. Its occurrence before term adds the risk of neonatal respiratory distress syndrome (NRDS) from hyaline membrane disease to the risk of chorioamnionitis , neonatal sepsis associated with ascending infection.

What causes premature rupture of membranes?**

• The exact etiology of PROM remains unknown, there have been many postulated causes, but a single common denominator has not yet been found.


• Infection: subclinical infection, chorioamnionitis

• coitus : patients who had coitus within 7 days before delivery.

• low socioeconomic conditions : less likely to receive proper prenatal care)

• sexually transmitted infections such as chlamydia and gonorrhea


• Previous preterm birth• Vaginal bleeding• Cigarette smoking during pregnancy• Trauma• Cervical incompetence/cervical lacerations

/cervical operations• Polyhydramnios/multiple gestations• Black patients are at increased risk of preterm

PROM compared with white patients.


• unknown causes

• There appears to be no single etiology of preterm PROM. It is likely that multiple factors predispose certain patients to preterm PROM.

Complications of Preterm PROM

Complications Incidence (%)

Delivery within one week 50 to 75

Respiratory distress syndrome 35

Cord compression 32 to 76

Chorioamnionitis 13 to 60

Abruptio placentae 4 to 12

Antepartum fetal death 1 to 2

What are the symptoms of PROM?

• The following are the most common symptoms of PROM. However, each woman may experience symptoms differently. Symptoms may include:

• leaking or a gush of watery fluid from the vagina

• constant wetness in panties

How is premature rupture of membranes diagnosed?*

• In addition to a complete medical history and physical examination, PROM may be diagnosed in several ways, including the following:

• an examination of the cervix (may show fluid leaking from the cervical opening)

• testing of the pH (acid or alkaline) of the fluid accuracy rate:93-96%

False-positive: cervicitis/vaginitis/presence of semen ,alkaline urine/blood

in vagina

• looking at the dried fluid under a microscope (may show a characteristic fern-like pattern)

Management

• Hospitalization• expectant management (in some cases of

PPROM, the membranes may seal over and the fluid may stop leaking without treatment)

• monitoring for signs of infection such as fever, pain, increased fetal heart rate, and/or laboratory tests

Management• corticosteroids ： that may help mature the lungs of

the fetus (lung immaturity is a major problem of premature babies). However, corticosteroids may mask an infection in the uterus.

• antibiotics (to prevent or treat infections)

• tocolytics - medications used to stop preterm labor.

• delivery (if PROM endangers the well-being of the mother or fetus, then an early delivery may be necessary to prevent further complications)

Documents

Fetal Distress