Multiple gestation

Dr shakeriAmir hospital

one of the most common high- risk condition

3% of all live birth

Triplets occurred 1in every 500 deliveries

Multiples result in -17% PTL /23% early PTL(less than 32w) -24%LBW /26% VLBW -16% neonatal deaths -the risk of dying before the first year . 5 times greater for twins . triples are at 17-fold greater risk

Increased risk of long term mental and physical handicaps

C.p 12 times more When matched for G.A and birth weight

multiples have threefold greater risk of C.P

Increased risk of growth restriction

Higher rates of congenital anomaly twin to twin

transfusion monoamnionicity cord prolaps PA,PP intrapartum

asphyxia birth truma

Higher health care cost NICU admission is required by one

fourth of twins ,three fourths of triplets and all quadruplets

Six times more hospitalized with an antepartum complications(PTL-PROM-preeclampsia)

Epidemiology and zygosity

Monozygotic(MZ) twins both fetuses arise from single fertilized

ova

Dizygotic(DZ) twins multiple ovulation with fertilization by

separate sperm

Monozygotic twins

Random event Independent to age ,race ,parity or

heredity Incidence is 3 to 4 per 1000 live births Increased frequency with ART

Dizigotic twins

Incidence is extremely variable The incidence are affected by personal

or family history The chance of second DZ twins is

increased twofold In first-degree relative with twins the

risk is increased Fathers family contributes little or

nothing to the hereditary risk

more frequent among older women Peaking in the mid thirties Majority of Increase has been result with

ART and induction ovulation Maternal race affected the frequency -7to10 /1000 live births among whites -10 to 40 /1000 live births among african -3 /1000 live births among asians -in white women the risk are more than

twice of black women ,which reflects a greater use of ART

Increased maternal pariaty Higher BMI Recent discontinuation of OCP Are also associated with

higher rates of DZ twinning

placentation

The placentation of DZ will always be diamniotic,dichorionic

Two complete placental units are produced

Separating membrane consist of four layers

Chorion begin to differentiate about day 3

Amnion begins to differentiate by about day8

If division occurs in first 3 days , two complete placental units will be formed

If division occurs between days 3and8 ,the placentation will be a single chorion and two amnions

If division occurs between days 8and 13,the twins will share a single amnion and chorion

Division after day13 ,producing conjoined twins

Examination of the placenta and dividing membrane are critical to determinated zygosity

Obstetrician can determine zygosity in delivery room in over 50%

Among MZ twins 18% to 36% diamniotic,dichorionic 1%monoamniotic,monochorionic 60%t070%diamniotic,monochorionic

Prenatal diagnosis The risk of aneuploidy is related to zygosity

and the mode of conception In DZ twins ,each fetus has an independent

risk for aneuploidy Like singletons is related to maternal age 33% of naturally occur twins will be MZ and

67%will be DZ Zygosity can be determined definitely by

genetic analysis But it can be diagnosed by determination of

chorionicity and fetal sex

First-trimester screening is similar to singleton pregnancy

Second-trimester screening in twins ,although with a decreased sensitivity and higher false positive rate

An attractive situation is first-trimester NT measurement

In dichorionic pregnancy ,the sensitivity and SPR(screen positive rate) of NT plus maternal age was similar singletons

In monochorionic pregnancies ,the SPR of NT was higher than singletons

This difference may be an early manifestation of TTTS

Maternal complications

Cardiovascular risks Significant expansion of the plasma

volume and COP Increased cardiac demand is well

tolerated in the absence of underlying cardiac disease such as MS

Tocolytic therapy have been associated pulmonary edema myocardial ischemia lethal tachyarrhythmia postpartum cardiomyopathy

Hematologic abnormalities Physiologic hemodilution Average Hgb is 10 g/dl at20 w Hgb below11g/dl in first or third

trimester represents iron deficiency anemia

Complicated 21%to36% of multiple gestations

Heme-rich animal protein+60mg//day elemental iron+1mg/day folic acid

Metabolic disorders

Lower fasting and postprandial G level Exaggerated insulin responses to

eating More rapid depletion of glycogen stores

and lipid metabolism between meals and during an overnight fast

Increased risk of gestational diabetes two to threefold

B-adrenergic agents and C.S can induce insulin resistance and hyperglycemia

preeclampsia

7% in singletons,14% in twins,21%for triplets and 40% for quadruplets

Frequently occurs earlier, sever and atypical

HT is not always the presenting sign Proteinuria is not universally present The most common presentation among

higher-order multiples was HELLP

PLACENTAL ABRUPTION

Threefold increased risk of abruption Occurs most frequently in the third

trimester Significant risk immediately after

vaginal delivery of the first infant

Hydramnios

Occurs in 2%to 3% of twins Twins account for 8% to 10% of all

cases of hydramnios May develop as a consequence of TTTS Idiopathic acute hydramnios with

maternal respiratory distress has been reported

Urinary tract infection

1.4-fold increased risk of UTI Usually involve the lower urinary tract To be a consequence of urinary stasis The incidence of pyelonephritis is not

significantly increased

Postpartum hemorrhage

Increased risk of .Uterine atony

.retention of placental tissue .surgical or mechanical trauma to genital tract .pharmacologic effects of medications such as mgso4

Increased risk of -cholestatic jaundice -pruritic urticarial plaques and papules

of pregnancy (PUPP) -hyperemesis -deep venous thrombosis ,varicose vein -shortness of breath, loss of balance

edema ,constipation and hemorrhoids

Vanishing twin syndrome

Spontaneous abortion or reabsorption of at least one of the multiples

Is most common in the first trimester Occurred in 20-50% of multiples When silent reabsorption occurs in first

trimester ,the prognosis for surviving twin is excellent

Fetal death in utero(acute intertwin transfusion syn)

After the first trimester, single fetal demise occures in 2-5% of twins and 10-15% of triplets

The risk is increased 3 to 4 fold by monochorionicity

Antenatal demise of a monochorionic twin is associated with 25% mortality rate

In dichorionic gestation the risk is minimal although higher rates of PTL and PPROM

Injury to the surviving twin was result of DIC and embolism through placental anastomosis

An acute transfusion into the death fetus through the shared placenta

May cause severe fetal hypotension and hypoxic end organ damage

Demise or neurologic injury in have occurred in third trimester

Following fetal demise ,management will depend on GA ,chorionicity and maternal and fetal status

In dichorionic twin ,no intervention is requied

Fetal demise In monochorionic twin is an indication for immediate delivery if fetal maturity or near maturity can be inferred

Monoamniotic twins

Fewer than 1% of MZ Fetal mortality rate 40% Cord entanglement is present in every

cases At greater risk of congenital anomaly

such as conjoining and TTTS Fetal demise occurred after 32 w

Management recommendation for monoamniotic twins

Confirm monoamniocity Sono at 18 to 20w to exclude

congenital anomalies and conjoining Parental education Serial sono for assessment of fetal

growth Daily fetal kick counts (26W) NST three times per week (26w) Antenatal C.S administration

Amniocentesis for lung maturity at 32 w

elective delivery at 34 to 35w if lung maturity not previously confirmed

C/S usually recommended If vaginal delivery is

planned ,continuous fetal monitoring is essential

Discordant twin growth

Ultrasound is useful for detection 15-30% of twins exhibit birth weight

differences of 20% When discordance is excessive >20-

25%,the smaller infant may be at risk for perinatal mortality and morbidity and disadvantages in long term physical and intellectual development

In monochorionic twins ,discordance is more frequent , sever and more likely to be associated with TTTS

Birth weight discordance and IUGR are interrelated

Prematurity and IUGR are mush greater threats than the degree of discordancy

Major cause of growth discordance - genetic dissimilarity -local placental implantation factors

The sensitivity of sonography for diagnosis discordance is only 60%

In evidence of 20-25% growth discordance or IUGR of either twin at ≥35w delivery is indicated

Twin-to-twin transfusion syn

TTTS is a serious complication affecting MZ/MC twins

Vascular communications are present in all monochorionic placentas but 1/3 of them have this syn

Sever TTTS identified in the second trimester is associated with loss rates 100% if untreated

The arterial donor twin may be growth retarded ,anemic ,hypotensive and oligohydramniotic

If there is little or no amniotic fluid , the amniotic membrane may lie in close apposition to the smaller fetus , restricting it to the uterine wall(stuck twin)

The venous recipient twin can become hypervolemic ,hyperviscous,hypertensive

and polyhydramniotic

Polyhydramnios contributes to a high incidence of premature labor or PPROM

Either twin may become hydropic The diagnosis of TTTS has become

controversial but now is diagnosed by using sonographic criteria including

Sonographic criteria of TTTS

Marked size disparity in fetuses of the same sex

Disparity in size between two sacs Disparity in size of the umbilical cords Single placenta Evidence of hydrops CHF in the recipient

Doppler may help to improve

diagnostic accuracy and fetal well-being

Quintero have defined TTTS as a deepest vertical pocket≤2cm in the donor with a deepest vertical pocket ≥8cm in the recipient

Management depending on the Quintero stage and GA

Delivery will depend on fetal maturity

Quintero staging criteria for TTTS

Stage1: bladder of donor still visible Stage2: bladder of donor no longer

visible Stage3: critically abnormal doppler

stadies Stage4: hydrops in one or both twins Stage5: demise of one or both twins

Management of TTTS

At earlier GA ,serial decompression amniocentesis and tocolytic therapy have been successful in prolonging pregnancy

Fetoscopy and direct laser occlusion of the placental vascular anomaly has become an option

Fetal and newborn complications

Prematurity IUGR Congenital anomalies

prematurity

Risk increases with the number of fetuses

Incidence of PTL IS 30-55% for twins,66-80% for trplets and 100% for quadruplets

Mean GA at delivery is related to fetal number: 39w for singletons-35 to 36w for twins-32 to 33w for triplets

IUGR

Is more common in multiple gestations In twins growth velocities similar to

singletons until 30 to 32w Triplet and quadruplet growth velocity

begin to slow at 27to 28 and 25 to 26w 1/3 of twins will demonstrate IUGR at

36-38w IUGR in multiples is asymmetric

Cause of IUGR relative placental insufficiency abnormal placental implantation umbilical cold abnormalities velamentous or marginal insertions structural or Ch abnormalities TTTS

IUGR is three times more common in twins

After 20w, fetal growth should be evaluated by sonogrphy on a monthly basis

The diagnosis of IUGR should lead to the institution of antenatal fetal surveillance inclusive of NST, BPP, assessment of Af and umbilical artery doppler velocimetry

If amniocentesis is used to assess lung maturity( single sampling necessary)

AF of larger twin should be sampled

Congenital anomalies

Occur twice in multiples more common in MZ than DZ The best time for evaluation of fetal

anatomy by ultrasound is 18-22w Sensitivity 88% Specificity 100%

Maternal nutrition Placental transfer of an adequate

nutrient supply is compromised after a combined fetal weight of 3000g is exceeded

In multiples , environmental factors such as nutrition adequacy has a greater influence on fetal growth than in singletons

Maternal weight gains of 24lb by 24w and overall 40 to 50lb are associated with optimal pregnancy outcome defined as twin birth weight >2500g

The importance of adequate early weight gain <24W

Poor weight gain prior to 24w has been associated with IUGR and higher perinatal mortality

Weight gain recommendation for twins based on the BMI such as singletons

Recommendation daily calories in twins is 3000 to 4000 kcal per day(20%protein -40%crbohydrates - 40%fat)

maternal anemia from iron and folate deficiency are common in multiples

supplemention of prenatal vit + iron 60 mg/day +folic acid 1 mg/day has been recommended

Heme –iron rich sources such as red meat , poultry, fish and eggs are emphasized

Calcium ,magnesium, zinc and their supplementation have recommended

ultrasound

Plays numerous critical roles in multiples

Diagnosis and presentation Determination of amnionicity and chorionicity Diagnosis of fetal or placental anomaly Fetal growth and Af volume Fetal biophysical parameters

A thin wispy membrane with a single placenta and same sex fetuses suggest monochorionicity

Thick dividing membrane, twin peak or lambda sign indicated diamniotic dichorionic intertwin membrane

Accuracy is more than 80-90% The determination is most accurate in

the first trimester

Multifetal pregnancy reduction

GA and birth weight at term are the two most important factors in perinatal morbidity and mortality

The technique is the transabdominal ,ultrasound-guided fetal intracardiac injection of kcl

Pregnancy loss rate prior to 24w dropped from 15-20% to 5-8%

MF.P.R of triplet and higher-order multiple gestations is associated with longer gestations ,higher birth weight , lower rates of perinatal mortality,NICU admission ,maternal antenatal hospitalization and C/S birth

Incidence of PIH ,gestational diabetes and other complications are not changed

Should be included in the counseling of all women with triplets and higher multiples

Corticosteroid administration

Recommended to women with - PTL prior to 34w - PPROM at <30-32w regardless of

plurality

Recommended only a single course

Fetal surveillance

Recommended in all situations for singleton pregnancy

NST and BPP CST is relatively contraindicated Initiated at 32w in monochorionic twins

and at 34w in dichorionic twins Performed on a weekly basis In IUGR, abnormal doppler and

monoamnionicity performed twice weekly or more frequent

Controversial interventions

Serial digital cervical examination Transvaginal ultrasound cervical length

measurements Ultrasound indicated cerclage Cervical and vaginal fetal fibronectin Reduce activities and rest Home uterine activity monitoring Tocolytic therapy

Serial digital cervical examination

Cervical score is calculated as follows: cervical length minus cervical dilation

CS ≤0 predicted PTL within 14 days CS greater than 0 are good candidates

for continued observation Should be done every 1-2 w basis

between 22 and 35w Is not associated with obstetric

complications

Transvaginal ultrasound cervical length measurements

≤25 mm at 24w was the best predictor of PTL in twins

≤15mm at a previable gestation have remarkably poor outcome

Cerclage for short cervix may be harmful in multiples

Cervical and vaginal fFN

In the late second and early third trimester is associated with an increased risk of PTL in multiples

Negative fFN is associated with <3% risk of delivery in the next 2 weeks

Reduced activities and rest

Has been associated with: reduced baseline uterine contraction pregnancy prolongation increased birth weights

Home uterine activity monitoring

The benefits of HUAM in twins remain controversial

There are no prospective data addressing the use of HUAM in triplets

Tocolytic therapy

Tocolytic therapy provide a short-term prolongation of pregnancy

Prolongation of 1 week in <32w will be associated with significant reduction in neonatal mortality and morbidity

The use of B-adrenergic agents is associated with increased pulmonary edema ,glucose level ,myocardial ischemia and cardiac arrhythmias

Mgso4 is most often used as tocolytic agents

When necessary ,the use of indomethacin in patients< 32w as an adjunct to Mgso4 or as a second line agent indicated To allow for an initial 48h to administrated C.S

Oral nifedipine 10-20mg/6h Oral or subcutaneous terbutaline

sulfate

Antepartum management protocol

16-22w(routine visits q2w) ║

routine baseline TVCL (18-20w)

║

TVCL <15mm consider cerclage

especially if HX of prior PTL<32w

22-26 weeks gestation Routine visit q2w if TVCL >25mm , but q1w

if TVCL ≤25mm TVCL <15mm at≤24w→cerclage or hospitalized bedrest TVCL15-25mm or positive fFN or CS≤0 discontinue work and activity/home bed rest/no intercourse/HUAM TVCL26-35mm or CS=+1 stop work and modified bed rest TVCL>35mm or negative Ffn or CS>+1 reassuring

26-35 weeks gestation Routine visits q2w if risk assessment neg Visit q1w if TVCL<30/+Ffn/CS≤+1 TVCL>35 or neg Ffn or CS>+1/reassuring TVCL≤35mm,positive fFN,CS≤0o Antenatal corticosteroidso Home bed resto HUAMo Tocolytic therapy if contractions presento Enhanced nutrition

Preterm birth risk assessment

Weekly digital exam Evaluate symptomatic patient with TVCL /fFN /urine culture / office UAM cervical /vaginal wet prep and cultures if symptomatic discharge

Nonbeneficial interventions

Prophylactic cerclage

Prophylactic tocolysis

Routine hospitalization

Prophylactic treatment with 17-OHPC did not reduce the rate of PTL in twins

Intrapartum management

Skilled obstetric attendants for labor and delivery

Nursing and neonatal care personnel Dual-monitoring cardiotocograph ultrasound scanning capability Intravenous access(16-18 gauge) Oxytocin infusion Nitroglycerin or terbutaline for uterin

relaxation

Methergine or 15-methyl PGF2a available to treat PPH

Obstetric forceps (piper) and vacuum extractor available

Immediate availability of blood and blood products

Anesthesiologist available at delivery and capability for emergency C/S

Timing of delivery The ideal time for delivery is uncertain The lowest fetal death rate in singleton

was 40-41w/ in twins was 36-37w/ in triplets was 34-35w

Significant discordance ,preeclampsia ,oligohydramnios ,IUGR or any other significant maternal-fetal complication after36w with twins or after34w with triplets is indication of delivery

data do not support prolongation of a twin or triplet pregnancy beyond 38 or 36 weeks, respectively ,due to the increased fetal and neonatal mortality and morbidity associated with high rates of IUGR

Route of delivery

Determined on presentation For twins is generally categorized into

three groups1. Twin A vertex, twin B vertex2. Twin A vertex, twin B nonvertex3. Twin A nonvertex

Twin A vertex/ Twin B vertex

40% of twin gestations More than 80% are successfully

delivered vaginally Presentation of second twin should be

confirmed following delivery of the first Change the presentation may occur in

10-20% If twin B IS larger than A ,safe and

successful vaginal delivery is still possible

Twin A vertex / Twin B nonvertex

40% of twins in labor Vaginal delivery of nonvertex second twin by

breech extraction appears to be the best approach for infants >1500g /external cervical version is another choice

If the second twin was larger(>500g) than the first ,C/S IS indicated

Decision on C/S for second twins <1500g should be based on the specific clinical situation and the experience of the operator

Twin A Nonvertex 20% of cases Vaginal delivery of these twins is

problematic and C/S is indicated For twins presenting breech/vertex ,the

possibility of interlock exists It is extremely rare but catastrophic Another complication of twin A is

cervical hyperextention Vaginal delivery is based on the

experience of staff and capability for emergency C/S

Triplets and higher-order multiples c/s is recommended If vaginal delivery is planned ,an

experienced obstetric team and capability for emergency C/S is necessary + estimated of weight more than 1500g + at least the first two triplets in a vertex presentation

Interval between deliveries

Delayed of more than 1 h have not associated with adverse outcomes for second twin , if continuous FHR monitoring is employed

Internal podalic version and breech extraction only when emergency delivery is mandated and C/S is not immediately available

After delivery of the first twin , a period of hypocontractility is happened

If labor has not resumed within the short time ,oxytocin infusion can be started

If the vertex is dipping into the inlet , amniotomy can be performed during contraction with moderate fundal pressure

Delayed interval delivery

If extremely preterm and previable birth occurs in twins ,occasionally D.I.D is indicated

This situation occurs in diamniotic, dichorionic twin gestation

CI include : significant hemorrhage ,hemodynamic

instability , intraamniotic infection and monochorionic placentation

Following delivery of first, the umbilical cord is tied, cut short and allowed to retract back into the uterus

Cerclage appears to offer a better chance

Aggressive use of perioperative tocolysis and broad –spectrum antibiotic is recommended in most protocols

Many clinicians prefer indomethacin for prophylactic tocolysis

Specific pathogens such as gonorrhea, chlamydia and group B streptococci should be identified and treated

Tocolytic therapy, antibiotic coverage and hospitalized observation are continued to the third trimester and occasionally to term

Postpartum management

Increased risk of uterine atony and PPH Mather should be monitored during the

initial hours after delivery Lactation consultation may be useful Follow –up and support for the mother

in the early weeks after delivery are important

Postpartum depression is more common