By Korda I.

Normal and Reassuring Patterns

The normal fetal heart rate range is between 120 and 160 beats per minute. A constant variation from the baseline (variability) reflects a healthy nervous system, chemoreceptors, baroreceptors and cardiac responsiveness. Beat-to-beat, or short-term, variability is an important indicator of fetal trouble. Loss of this variability may indicate an ominous condition, but it can also indicate healthy rest-activity in the fetus or depression of the central nervous system due to medication. An increase in variability may indicate acute hypoxia or mechanical compression of the umbilical cord

Fetal distressan abnormal condition of a fetus; usually discovered during

pregnancy and characterized by an abnormal heart rhythmDecreased movement felt by the mother or Fetal

hyperactivityMeconium in the amniotic fluidCardiotocography signs increased or decreased fetal heart rate (tachycardia and

bradycardia), especially during and after a contractionBiochemical signs, assessed by collecting a small sample of

baby's blood from a scalp prick through the open cervix in labour

fetal acidosiselevated fetal blood lactate levels indicating the baby has a

lactic acidosisFetal heart rate less than 120 or greater than 160 beats per

minuteProgressive decrease in baseline variabilityLate decelerationSevere variable decelerations

Causes

There are many causes of fetal distress:

Breathing problemsAbnormal position and

presentation of the fetusMultiple birthsShoulder dystociaUmbilical cord prolapseNuchal cordPlacental abruptionPremature closure of the

fetal ductus arteriosus

Treatment

In many situations fetal distress will lead the obstetrician to recommend steps to urgently deliver the baby. This can be done by labor induction, or in more urgent cases, a caesarean section may be performed.

CAUSES of Multifetal gestation :

Increasing maternal age

Increasing parityNutritional factorsPituitary gonadotropinInfertility therapyAssisted reproductive

therapy

Fraternal TwinFertilization of two separate ova“double – ovum”, or dizygotic Identical TwinsTwins arise from single fertilized ovum“single-ovum”, monozygoticHave increased incidence of discordant

malformations

Superfetation An interval as long as or longer than a

menstrual cycles intervenes between fertilizations.

Requires ovulation and fertilization during the course of an established pregnancy

Not yet proven in humans SuperfecundationFertilization of two ova within the same

menstrual cycle but not as the same coitus, nor necessarily by sperm from the same male.

Genesis of Monozygotic Twinning

Determination of Zygosity

UltrasoundCan determine zygosity as early as the first trimesterDizygotic: presence of two separate placentas and a

thick – generally 2mm or greater – dividing membrane (“twin – peak” sign)

Monozygotic: membrane generally less than 2mm in thickness and reveals only 2 layers. ( “T” sign) 

Placental ExaminationVisual examination of the placenta and membranesPlacenta should be carefully delivered to preserve the

attachment of the amnion and chorion to the placentaInfant Sex and ZygosityTwins of the opposite sex are almost always dizygotic

Diagnosis of Multiple Fetuses

In women with a uterus that appears large for gestational age, the following possibilities are considered:

Multiple fetuses Elevation of the uterus by a distended bladder Inaccurate menstrual history Hydramnios Hydatidiform mole Uterine myomas A closely attached adnexal mass Fetal macrosomia (late in pregnancy)

Diagnosis of Multiple FetusesUltrasonography Separate gestational

sacs can be identified early in twin pregnancy

Two fetal heads or two abdomens should be seen in the same plane, to avoid scanning the same fetus twice and interpreting it as twins.

Diagnosis of Multiple FetusesRadiologic ExaminationNot useful and may lead to an incorrect

diagnosis

Biochemical TestAmounts of chorionic gonadotropin in plasma

and in urine, on average, are higher than those found with a singleton pregnancy, but not so high as to allow a definite diagnosis of multiple fetuses

Maternal AdaptationNausea and vomiting in excess of that

characterizing singleton pregnancies.Maternal blood volume expansion is greaterIncreased in cardiac out of 20%Blood loss for twin delivery via NSD 935 ml

Pregnancy OutcomeAbortionMalformation

- Defects resulting from twinning itself. This category includes conjoined twinning, acardiac anomaly, sirenomelia, neural-tube defects, and holoprosencephaly.- Defects resulting from vascular interchange between monochorionic twins. Vascular connections may also conduct dramatic blood pressure fluctuations, causing defects such as microcephaly, hydranencephaly, intestinal atresia, aplasia cutis, or limb amputation.- Defects that occur as the result of crowding.

Low birthweightPreterm birth

Conjoined TwinsAnterior (thoracopagus)Posterior (pygopagus)Cephalic (craniopagus)Caudal (ischiopagus)

Conjoined Twins

Acardiac TwinTwin reversed-arterial-perfusion (TRAP) sequence is

a rare (1 in 35,000 births) but serious complication of monochorionic, monozygotic multiple gestation.

In the TRAP sequence, there is usually a normally formed donor twin who has features of heart failure as well as a recipient twin who lacks a heart (acardius) and various other structures.

Caused in the embryo by a large artery-to-artery placental shunt, often also accompanied by a vein-to-vein shunt.

The perfusion pressure of the donor twin overpowers that in the recipient twin, who thus receives reverse blood flow from its twin sibling.

Acardiac Twinacardius acephalus -

Failure or disrupted growth of the head

acardius myelacephalus - partially developed head with identifiable limbs

acardius amorphous - failure of any recognizable structure to form

ManagementWithout treatment, the donor or "pump" twin

has been reported to die in 50 to 75 percent Methods of in utero treatment of acardiac

twinning: goal is interruption of the vascular communication between the donor and recipient twins.

Twin to Twin TransfusionBlood is transfused from a

donor twin to its recipient sibling such that the donor becomes anemic and its growth may be restricted, whereas the

Recipient becomes polycythemic and may develop circulatory overload manifest as hydrops.

Donor twin - pale, recipient sibling – plethoric

Fetal consequences:circulatory overload with heart

failure Occlusive thrombosis is also

much more likely to develop in this setting.

Polycythemia may lead to severe hyperbilirubinemia and kernicterus

Pathophysiology:Presence of solitary, deep arteriovenous

channels within the capillary beds of the villous tissue.

Velamentous umbilical cord insertion may contribute to the development of unequal fetal blood volumes because the membranously inserted cord can be easily compressed, restricting blood flow to one twin.

Diagnosis:postnatal diagnosis:

- weight discordancy between twins of 15 – 20%- hemoglobin level difference of 5 g/dL or greater

Typically presents in the midtrimester when the donor fetus becomes oliguric due to decreased renal perfusion.

Develops oligohydramnios, and the recipient fetus develops severe hydramnios, presumably due to increased urine production.

Virtual absence of amnionic fluid in the donor sac prevents fetal motion, giving rise to the descriptive term stuck twin.

Hydramnios–oligohydramnios combination can lead to growth restriction, contractures, and pulmonary hypoplasia in one twin, and premature rupture of the membranes and heart failure in the other.

Management:amnioreduction septostomylaser ablation of vascular anastomosesselective feticide

Discordant TwinsSize inequality of twin fetuses, which may be a

sign of pathological growth restriction in one fetus, is calculated using the larger twin as the index.

As the weight difference within a twin pair increases, perinatal mortality increases proportionately.

Restricted growth of one twin fetus usually develops late in the second and early third trimester and is often asymmetrical.

Earlier discordancy is usually symmetrical and indicates higher risk for fetal demise.

The earlier in pregnancy discordancy develops, the more serious the sequelae.

PathologyIn monochorionic twins, discordancy is

usually attributed to placental vascular anastomoses that cause hemodynamic imbalance between the twins.

Dizygotic fetuses may have different genetic growth potential, especially if they are of opposite genders.

DiagnosisWeight of larger twin minus weight of

smaller twin, divided by weight of larger twin.Most useful index of size discordancy -

ultrasonographic assessment of twin discordancy: abdominal circumference superior to head circumference, femur length, or transverse cerebellar diameter

ManagementUltrasonographic monitoring of growth within a

twin pair has become a mainstay in the management.

Other ultrasonographic findings, such as oligohydramnios, may be helpful in gauging fetal risk.

Depending on the degree of discordancy and the gestattional age, fetal surveillance may be indicated, especially if one or both fetuses exhibit growth restriction.

Delivery is usually not performed for size discordancy alone, except occasionally at advanced gestational ages.

Death of One FetusPrognosis for the surviving twin depends on the

gestational age at the time of the demise, the chorionicity, and the length of time between the demise and delivery of the surviving twin.

Early demise such as a "vanishing twin" does not appear to increase the risk of death in the surviving fetus after the first trimester.

Later in gestation, the death of one of multiple fetuses could theoretically trigger coagulation defects in the mother.

Management decisions should be based on the cause of death and the risk to the surviving fetus.

Majority of cases of a single fetal death in twin pregnancy involve monochorionic placentation.

Antepartum Management of Twin PregnancyDelivery of markedly preterm infants be

prevented.Failure of one or both fetuses to thrive be

identified and fetuses so afflicted be delivered before they become moribund.

Fetal trauma during labor and delivery be avoided.

Expert neonatal care be available.

DietRequirements for calories, protein, minerals,

vitamins, and essential fatty acids are further increased in women with multiple fetuses.

Caloric consumption should be increased by another 300 kcal/day.

Supplementation with 60 to 100 mg/day of iron and with 1 mg of folic acid is recommended.

Antepartum SurveillanceAssessment of amnionic fluid volume -

associated oligohydramnios may indicate uteroplacental pathology and should prompt further evaluation of fetal well-being.

The nonstress test or biophysical profile is commonly used in management of twin or higher-order multiple gestation.

Doppler evaluation of vascular resistance - Increased resistance with diminished diastolic flow velocity often accompanies restricted fetal growth.

Prevention of Preterm DeliveryBedrestTocolytic therapyCorticosteroids for lung maturationCerclage – not been shown to improve

perinatal outcomeTwin gestation with preterm ruptured

membranes are managed expectantly much like singleton pregnancies.

Delivery of Twin FetusesComplications of labor and deliverypreterm labor, uterine contractile dysfunctionabnormal presentation, prolapse of the

umbilical cordpremature separation of the placentaimmediate postpartum hemorrhage

Recommendations for intrapartum management include:An appropriately trained obstetrical attendant should

remain with the mother throughout labor. Continuous external electronic monitoring or, if the membranes are ruptured and the cervix dilated, simultaneous evaluation of both the presenting fetus by internal electronic monitoring and the remaining sibling(s) by external monitors, is typically used.

Blood transfusion products should be readily available.An intravenous infusion system capable of delivering

fluid rapidly should be established. In the absence of hemorrhage or metabolic disturbance during labor, lactated Ringer or an aqueous dextrose solution is infused at a rate of 60 to 120 mL/hr.

An obstetrician skilled in intrauterine identification of fetal parts and in intrauterine manipulation of a fetus should be present.

Recommendations for intrapartum management include:An ultrasonography machine should be readily available

to help evaluate the position and status of the remaining fetus(es) after delivery of the first.

An experienced anesthesiologist should be immediately available in the event that intrauterine manipulation or cesarean delivery is necessary.

For each fetus, two people, one of whom is skilled in resuscitation and care of newborns, are appropriately informed of the case and remain immediately available.

The delivery area should provide adequate space for all members of the team to work effectively. Moreover, the site should be appropriately equipped to take care of any maternal problems plus resuscitation and maintenance of each neonate.

Presentation and PositionMost common presentations at admission for delivery

- cephalic–cephalic - cephalic–breech - cephalic–transverse

These presentations, especially those other than cephalic–cephalic, are unstable before and during labor and delivery

Compound, face, brow, and footling breech presentations are relatively common, especially when the fetuses are small, amnionic fluid is excessive, or maternal parity is high.

Analgesia and AnesthesiaEpidural analgesia is recommended by many

clinicians because it provides excellent pain relief and can be rapidly extended cephalad if internal podalic version or cesarean delivery is required.

Vaginal DeliveryWhen the first twin is cephalic, delivery can usually

be accomplished spontaneously or with forceps.As in singletons, when the first fetus presents as a

breech, major problems are most likely to develop if:- fetus is unusually large and the aftercoming head is larger than the capacity of the birth canal.- Fetus is sufficiently small so that the extremities and trunk are delivered through a cervix inadequately effaced and dilated to allow the head to escape easily.- umbilical cord prolapses.

Vaginal Delivery of the Second TwinAs soon as the presenting twin has been

delivered, the presenting part of the second twin, its size, and its relationship to the birth canal should be quickly and carefully ascertained by combined abdominal, vaginal, and at times intrauterine examination.

Vaginal Delivery of the Second TwinIf the fetal head or the breech is fixed in the birth:moderate fundal pressure is applied and

membranes are ruptured. digital examination of the cervix is repeated to

exclude prolapse of the cord. Labor is allowed to resume, and the fetal heart

rate is monitored. With reestablishment of labor there is no need to

hasten delivery unless a nonreassuring fetal heart rate or bleeding develops.

If contractions do not resume within approximately 10 minutes, dilute oxytocin may be used to stimulate contractions.

Vaginal Delivery of the Second TwinIf the occiput or the breech presents immediately over

the pelvic inlet but is not fixed in the birth canalPresenting part can often be guided into the pelvis by

one hand in the vagina while a second hand on the uterine fundus exerts moderate pressure caudally.

Alternatively, an assistant can maneuver the presenting part into the pelvis using ultrasonography for guidance and to monitor heart rate.

It is essential to have an obstetrician skilled in intrauterine fetal manipulation and an anesthesiologist skilled in providing anesthesia to effectively relax the uterus for vaginal delivery of a noncephalic second twin to obtain a favorable outcome.

Interval between First and Second Twins

The American College of Obstetricians and Gynecologists (1998) has determined that the interval between delivery of twins is not critical in determining the outcome of the twin delivered second.

Cesarean DeliveryThe American College of Obstetricians and

Gynecologists (1998) has concluded that, in general, cesarean delivery is the method of choice when the first twin is noncephalic.

It is important to place patients in a left lateral tilt so as to deflect the uterine weight off the aorta to avoid hypotension.

The uterine incision should be large enough to allow atraumatic delivery of both fetuses.

It is important that the uterus remain well contracted during completion of the cesarean delivery and thereafter.

Remarkable blood loss may be concealed within the uterus and vagina and beneath the drapes during the time taken to close the incisions.

Thanks for attention!!!