TWINS: MORE THAN TWICE THE TROUBLE
From A Day With The Perinatologist: Perspectives in Practice, sponsored by Creighton University Medical Center, Omaha,
NE
John P. Elliott, MD, Director, Maternal-Fetal Medicine, Banner Good Samaritan Medical Center, Phoenix, AZ
Educational Objectives
| The goal of this program is to improve the management and reduce risks associated with twin gestations. After hearing
and assimilating this program, the clinician will be better able to:
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 | 1. Determine chorionicity in a twin gestation.
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| 2. Identify risks associated with twin gestations.
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| 3. Provide obstetric care for the woman pregnant with twins.
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| 4. Recognize the importance of implementing prenatal care targeted at identifying women at risk for preterm labor.
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| 5. Explain the rationale for using home uterine activity monitoring.
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Faculty Disclosure
In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the
planning committee to disclose relevant financial relationships within the past 12 months that might create any personal
conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes
quality in health care and not a proprietary business or commercial interest. For this program, the following has been
disclosed: Dr. Elliott is on the Speaker’s Bureau of Matria Healthcare and Adeza. The planning committee reported
nothing to disclose.
Acknowledgments
Dr. Elliott was recorded at A Day With The Perinatologists: Perspectives in Practice, sponsored by Creighton University
School of Medicine, Department of Obstetrics and Gynecology, and the Continuing Medical Education Division,
held on September 14, 2007 in Omaha, NE. The Audio-Digest Foundation thanks Dr. Elliott and the Creighton University
School of Medicine for their cooperation in the production of this program.
| General considerations: incidence—twins accounted for ≈3.5% of all deliveries in 2007; incidence increasing
(≥2.5 times) because of older maternal age and fertility treatments; mortality—3 to 7 times that of singletons;
accounts for 12% of perinatal mortality (but only 3% of deliveries); risk for preterm delivery 55%, compared
to 12% in singletons; incidence of intrauterine growth restriction (IUGR) and structural and chromosomal
anomalies significantly higher than with singletons
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| Chorionicity: monochorionic—one placenta; risk for twin-to-twin transfusion syndrome (TTTS); twins identical;
dichorionic—two-thirds of twins; separate placenta and amniotic sac; twins either identical or fraternal
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| Prematurity: of twins delivered preterm, ≈50% due to preterm labor, 10% due to preterm premature rupture of
membranes (PPROM), 20% due to maternal com-plications, and 25% due to preterm elective delivery;
mother’s discomfort not justification for elective delivery; preterm delivery associated with poor long-term
outcomes; consider only as last resort; study—385 twin pregnancies delivered at Yale-New Haven Hospital;
4% at <25 wk gestation; 6% at 25 to 28 wk, ≈20% at 24 to 28 wk, ≈13% at 29 to 32 wk, 29% at 33 to 36 wk,
and 50% at 37 to 40 wk; for twins, average age at time of delivery 36.5 wk
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| Establishing placentation: early ultrasonography (US) to determine chorionicity recommended;
dichorionic—twin peak sign (placental tissue indents membranes between fetuses); thick membrane easily
visible; different sexes; monochorionic—thin wispy spider web-type membrane; extreme difficulty in identifying
membrane; incidence of monochorionic, monoamniotic twinning, ≈1%; same sex; chorionicity can be
established in >95% of twin gestations; if chorionicity cannot be determined, manage as if monochorionic
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| Low birth weight (LBW) and very low birth weight (VLBW): incidence of LBW (<2500 g) in singletons
≈6%, compared to 50% for twins (due to growth problems and prematurity); VLBW (<1500 g) 2% in singletons
vs 10% in twins
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| Cerebral palsy: incidence 0.24% in singletons, 0.6% to 1.2% in twins (regardless of gestational age); incidence
in VLBW infants 25 to 31 times that in normal term, regular birth weight gestations
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| Spontaneous abortion: 2 times rate associated with singleton gestations; “vanishing twin” (spontaneous loss of
one twin) occurs in ≈25% of twin gestations; no increased adverse outcome if monochorionic twin gestation
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| Congenital anomalies: incidence about double that of singletons; incidence in monochorionic twins double
that of dichorionic twins
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| Anemia: 40% of twins iron-deficient
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| Preeclampsia: risk ≈6% to 7% for singletons; likely 25% for twins; risk greater with 2 placentas; paternal antigens
incite preeclamptic response in mother; prophylactic treatment with baby aspirin (81 mg daily) and
calcium (2000 mg daily) recommended; prophylaxis controversial, but data suggest benefit in certain high-
risk pregnancies
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| IUGR: estimated fetal weight (EFW) <10th percentile for singleton gestation; discordance (>25% difference
in EFW between twins, expressed as percentage of larger twin’s weight)
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| Incompetent cervix: occurs between 18 and 25 wk of gestation; with twins, etiology hormonal (not mechanical
or congenital problem); increase in relaxin (produced by ovary, increases in multiple gestations and
forced ovulation); speaker recommends US of cervical length at 18, 20, 22, and 24 wk gestation; evaluate
for contractions if cervical length shortened (≤2.5 cm)
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| TTTS: unique to monochorionic twins; incidence 5% to 30%; ≈15% chance of acute severe TTTS in second
trimester; blood vessels from umbilical cord of both fetuses connect on surface of placenta; unequal sharing
of blood supply; blood shunted away from one twin; diagnosis made when >1.5-wk difference in size of
twins seen; recipient twin develops polyhydramnios (single deepest pocket ≥8 cm); donor twin develops
oligohydramnios; in monochorionic pregnancy, perform US every 2 wk between 18 and 26 wk gestation;
TTTS can develop in third trimester, but usually not as severe as in second trimester
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| Diabetes: occurs in ≈7.5% of twins, compared to ≈5.5% of singletons
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| Nutrition: target weight gain, 40 to 50 lb; high-protein, high-calorie diet; supplemental iron, folic acid, and
calcium
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| Dichorionic diamniotic: early diagnosis; level II targeted US at 18 wk; cervical length US every 2 wk; from
24 wk to delivery, growth US every 4 wk (every 3 wk with evidence of growth discordance or IUGR); delivery
at 37 to 38 wk (placenta does not function as well beyond 38 wk gestation [ie, potential problems and
stillbirth])
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| Monochorionic diamniotic: early diagnosis; between 16 and 26 wk gestation, evaluate every 2 wk (looking at
size and amniotic fluid volume); level II targeted US at 18 wk (genetic screening if patient desires); between
18 and 24 wk, cervical length US every 2 wk (can be performed vaginally as opposed to abdominally);
at 26 wk (with no evidence of TTTS), US every 2 to 3 wk; delivery at 36 wk
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| Monochorionic monoamniotic twins: high risk for sudden fetal death from cord entanglement; 3% to 4%
risk for TTTS; admit patient to hospital at 24 to 26 wk; 1 hr of monitoring per shift (total 3 hr/day); Heyborn
et al established better outcome with inpatient management and monitoring; delivery probably best between
32 and 34 wk
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| Office visits: from 20 wk through delivery, schedule every 2 wk; digital cervical examination each visit;
whether singleton or multiple gestation, ask patient about signs and symptoms of preterm labor (eg, backache,
change in vaginal discharge)
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| Fetal fibronectin: helpful in management; negative test does not imply patient not at risk for preterm delivery;
obtain sample every 2 wk, from 24 to 32 wk, whether patient symptomatic or not; chance of delivery in next
2 wk, 3% to 4% with negative test (25% to 30% with positive test)
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| Home uterine activity monitoring (HUAM): better at measuring contractions than hospital monitoring;
Dyson et al demonstrated extended assessment reduced occurrence of preterm delivery from preterm labor,
compared to standard of care (ie, no intervention); daily nursing contact shown to be as beneficial as
HUAM plus nursing contact; insurance does not cover daily nursing contact; system of HUAM plus nursing
contact superior to standard of care
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| Antepartum fetal assessment
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| Dichorionic diamniotic: modified biophysical profile (BPP; nonstress test plus amniotic fluid index) or BPP
twice weekly; no testing necessary in fetuses with concordant growth and weight average for gestational
age; start at diagnosis with evidence of IUGR in one or both fetuses (probably should initiate with discordance
>25%)
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| Monochorionic diamniotic: modified BPP better than BPP; concordant growth at 32 wk; if IUGR seen in one
or both twins, start at diagnosis
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| Monochorionic monoamniotic: fetal nonstress test only, BPP not useful; monitor all patients
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| Delivery: 38 wk considered post dates for twins; monochorionic diamniotic twins at risk for acute blood
volume shifts, even in labor; vertex-vertex presentation—vaginal delivery permissible and advised; vertex-
other presentation—cesarean delivery or vaginal delivery; other than vertex presentation—cesarean delivery
recommended
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| Intrapartum complications: malpresentation—data suggest second twin best delivered by breech extraction;
vertex-vertex—incidence 17%; cesarean delivery for second twin; be prepared for complications from second
twin; American College of Obstetricians and Gynecologists (ACOG) recommends delivery in operating
room with preparation for possible complications (eg, cord prolapse, placental abruption, bradycardia);
neonatal complications—twins account for 40% of admissions to neonatal intensive care unit (NICU); average
length of stay 18 days; issues—malformations; TTTS; economics of multiple gestations—charges surrogate
for outcome; costs decrease as gestational age increases; lower the cost, better the clinical outcome
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| Situations requiring consultation or transfer of care: monochorionic monoamniotic twins, conjoined
twins, maternal risk factors (eg, diabetes, hypertension, poor obstetric history), twins remaining from selective
reduction, twins with amniotic fluid abnormalities, (ie, polyhydramnios, oligohydramnios), twins with major
congenital anomalies, twins with acute complications at <34 wk, and twins with severe IUGR
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| Nursing issues with twin gestations: monitoring both twins in labor or fetal nonstress testing situation challenging;
twin monitor helps in distinguishing between twins; monitor both twins (internal scalp electrode on
first twin, external on second); labor pattern often different (ie, big contractions, dysfunctional patterns); caution
when administering oxytocin (Pitocin; properties of distended twin uterus different from those of singleton
uterus); more magnesium sulfate (4 g) often required for tocolysis; be prepared for immediate cesarean
delivery of second twin
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| Fetal death of one twin: overall incidence, ≈2% to 5%; ≈20% with dichorionic placentation; almost 60% with
monochorionic placentation; severe morbidity (generally cerebral palsy) in dichorionic placentation (11%);
morbidity 30% if monochorionic placentation; fetal death of one twin in monochorionic diamniotic pregnancy
should not trigger delivery of second twin, unless death witnessed on fetal heart rate monitor (if so, deliver
surviving twin immediately); injury to deceased fetus due to volume shifts with loss of blood pressure
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Suggested Reading
ACOG Practice Bulletin: Multiple gestation: Complicated twin, triplet and high-order pregnancy. 2004, No. 56;
Cruikshank DP: Intrapartum Management of twin gestations. Obstet Gyne 109, 1167, 2007; Dyson DC et al:
Monitoring women at risk for preterm labor. N Engl J Med 338:15, 1998; Heyborne KD et al: Improved perinatal
survival of monoamniotic twins with intensive inpatient monitoring. Am J Obstet Gynecol 192:96, 2005; Leduc L et
al: Persistence of adverse obstetric and neonatal outcomes in monochorionic twins after exclusion of disorders
unique to monochorionic placentation. Am J Obstet Gynecol 193:1670, 2005.
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