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Multiple Gestation (2005) Implications of Chorionicity Ultrasonography of Nuchal Cords


Color Doppler Ultrasound of Nuchal Cord Color Doppler imaging correctly identifies 72% of single, and 94% of multiple nuchal cords found at birth. – PowerPoint PPT presentation

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Title: Multiple Gestation (2005) Implications of Chorionicity Ultrasonography of Nuchal Cords

Multiple Gestation (2005)Implications of
ChorionicityUltrasonography of Nuchal Cords
  • David M. Sherer, MD
  • Professor of Obstetrics and Gynecology
  • State University of New York (SUNY),
  • Downstate Medical Center
  • Brooklyn, NY

Multiple Gestations (2005)Implications of
Twin Gestation
  • Marked recent increase in the incidence of
    twinning and other high-order multiple gestations
    reflects impact of ART
  • Current incidence 140 deliveries
  • Approximately 50 of twin gestations currently
    result from infertility treatment.
  • Increased representation of older patients
    already at increased risk for adverse perinatal

Twin Gestation
  • Significantly increased perinatal morbidity and
    mortality rates in comparison with singleton
  • Perinatal mortality rate 3-7 fold higher than
    among singletons.
  • While accounting for only 2.5 of the population,
    twins account for 12.6 of all perinatal

Twin Gestation
  • Monozygotic twinning constant across populations
  • 1 in 250 births
  • independent of maternal age and parity
  • Dizygotic twinning rates vary between
  • 1 in 20 and 1 in 500 births
  • rates vary with maternal age, parity, genetic
    factors and ART
  • It is estimated that 20 of all twins are
    monochorionic and 80 are dichorionic
  • Monozygotic and monochorionic twins are
    associated with a relatively high incidence of
    perinatal morbidity and mortality

Increased Morbidity Mortality
  • Preterm birth
  • Fetal growth restriction
  • Low birthweight
  • Congenital anomalies

Increased Morbidity Mortality
  • Problems unique to twin gestations
  • Twin Twin Transfusion, Twin Reverse Arterial
    Perfusion, Conjoined Twins, Cord Entanglement
  • Twofold increase in spontaneous abortion
  • Birth trauma
  • Overall increase in maternal complications
    (preeclampsia, pregnancy-induced hypertension,
    gestational diabetes, placental abruption,
    placenta previa, both ante and postpartum

Twin GestationMorbidity and Mortality
  • Perinatal mortality rate for monozygotic twins is
    approximately 3 fold higher than for dizygotic

Twin GestationMorbidity and Mortality
  • Mortality in monochorionic twin gestations is
    almost twice as high as dichorionic twin
    gestations (and fourfold higher than singletons)
  • (Machin G, et al Am J Med Genet 19955571-6)

Hidden Mortality of Monochorionic Twin
  • Data from nuchal translucency screening of 102
    monochorionic and 365 dichorionic twins
  • Higher rate of fetal loss prior to 24 weeks
    gestation (12.2 vs.1.8)
  • Perinatal mortality lt 32 wks (2.8 vs. 1.6)
  • Prevalence of preterm delivery (9.2 vs. 5.5)
  • Prevalence of birthweight lt 5th centile in both
    twins (7.5 vs. 1.7)
  • While overall, MC twins sustained a 3 fold
    increase in loss of both twins in comparison with
    DC twins, the proportion of birthweight
    discordancy gt 25 was similar (11.3 vs.12.1)
  • (Sebire et al. BJOG 19971041203-7)

TVS depiction of chorionic and amniotic type at lt
14 wks
  • 212 multifetal gestations scanned lt 14 wks
  • Number of fetuses and chorionic and amniotic were
    determined ultrasonographically
  • Of 212, 54 delivered in the authors institution,
    and of these 43 had pathology assessment of the
    placenta (40 twins and 3 sets of triplets)
  • All US membrane assessments were precise
  • Conclusion TVS US lt 14 wks accurately depict
    chorion and amnion type in multifetal pregnancies
  • (Monteagudo A et al AJOG 1994170824-9)

Chorionicity and Perinatal Outcome
  • Perinatal morbidity and mortality differ among
    twin gestations of varying membrane and placental
  • Compared with dichorionic twins, monchorionic
    twins exhibit a 3-5 fold higher incidence of
    perinatal morbidity and mortality
  • (Bajora R, Kingdom J. Prenat Diagn 1997171207)

Chorionicity and Perinatal Outcome
  • Prospectively assessed outcomes of 68 twin
    gestations diagnosed in the first-trimester with
    two active fetal hearts as a function of
  • The outcome of dichorionic twin gestations was
    significantly better than monochorionic twins
    (83 vs. 56 delivered twins, 12 vs. 11
    delivered singletons and 5 vs. 33 none,
  • Interestingly among dichorionic twins, pregnancy
    outcome was less favorable when diagnosed between
    6 -8 weeks vs. 8-13 weeks
  • (Benson C. Ultrasound Obstet Gynecol

Chorionicity and PerinatalOutcome
  • Retrospective cohort study of 44 MC and 164 DC
    twin gestations followed gt 20 weeks assessed the
    effect of chorionicity on infant outcome at 1
    year of age
  • Adverse outcomes (death, cerebral palsy and
    mental retardation) occurred in 10 (9/88) of MC
    vs. 3.7 (12/328) DC infants.
  • Delivery did occur on average 1 week earlier
    (34.72.8 vs 35.7 2.3) in MC vs. DC twins
  • (Minakami et al. J Reprod Med 199944595-600)

Chorionicity PerinatalOutcome
  • However, no significant difference in GA at birth
    or birthweight were noted between 9 MC and 12 DC
    infants with adverse outcomes
  • TTT was considered etiology of adverse outcome in
    7 MC infants
  • All nine MC and 33 (4/12) DC infants with
    adverse outcomes belonged to twin pairs that had
    birthweight discordancies
  • 25
  • (Minakami et al. J Reprod Med 199944595-600)

Fetal Death of One Twin
  • Antepartum death of a single fetus complicates
    between 2.5 and 5 of all twin gestations and is
    associated with significant morbidity and
    mortality in the survivor

Fetal Death of One Twin
  • Intrauterine fetal demise of one of the twins is
    3-4 times more common in monochorionic twins, yet
    by no means unique to MC gestations
  • Carlson and Towers reported 17 cases of a fetal
    death among 642 multiple gestations
  • No major morbidity or mortality occurred among
    survivors of dichorionic twins
  • (Carlson and Towers, Obstet Gynecol 198973685-9)

Fetal Death of One Twin
  • Compared outcomes between 50 MC vs. 42 DC twin
    gestations with one fetal demise
  • Among MC twins, the incidence of fetal demise of
    the co-twin (13/50 vs. 1/42) and total perinatal
    mortality rate (29/50 vs. 9/42) were higher in
    the MC group
  • Among MC group anemia was noted in 19/37 of the
    surviving co-twins
  • (Bajora et al. Hum Reprod 1999142124-300)

Twin Gestation
  • Fetal testing of twins includes
  • Fetal movement assessment
  • Nonstress testing
  • Biophysical profile
  • Doppler velocimetry
  • US (interval fetal growth)
  • The above surveillance methods have not been
    assessed prospectively (randomized or sratified
    according to chorionicity)

Twin Gestation
  • Assessed 37 patients with twins who received care
    prior to 32 weeks with25 patients with no care/or
    presented gt32 weeks
  • Statistically significant differences were noted
    in the perinatal mortality rate of monitored
    (68/1000) vs. non-monitored patients (160/1000).
  • Significant differences were observed in mean
    birthweights (2645 g vs. 2007 g, respectively)
  • (Gardner et al, J Reprod Med 199035519-21)

Twin Gestation
  • Randomized 8662 women to receive (or not receive)
    routine US screening
  • All twins were detected in the US group vs. 76.3
    of controls.
  • Perinatal mortality was 27.8/1000 vs. 65.8/1000
    among controls
  • (Helsinki Ultrasound Trial, Saari Kempainen et
    al, Lancet 1990336387-91)

  • A marked lack of objective evidence-based data
    are available as to the precise preferred
    surveillance modalities and recommended intervals
    between testing of twins in general, irrespective
    of chorionicity.

  • It appears reasonable to maintain that
  • The DC twin gestation represents a high-risk
  • The MC-DA twin gestation represents a very
    high-risk pregnancy
  • The MC-MA twin gestation represents an extremely
    high-risk pregnancy

  • Early prenatal knowledge of chorionicity is
  • Nevertheless, at least until definitive
    (prospective randomized) data become available,
    DC twin gestations should not be exempted from
    increased fetal surveillance applied to twins
  • Twins should be followed routinely with interval
    US growth assessments (3-4 week intervals)
  • Targeted surveillance of MC twins may be
    implemented at critical (early) gestational ages

Prenatal Ultrasonographic Diagnosis of Nuchal
Pathogenesis of Nuchal Cords
  • Unclear.
  • It appears that fetal movements may result in the
    formation of nuchal cords.
  • Excessive fetal movement and long umbilical cords
    - are prone to entanglement.
  • Does not explain why some fetuses develop nuchal
    cords and others do not.

Incidence of Nuchal Cords
  • Frequency of nuchal cords increases with
    advancing gestational age (from 5.8 to 29.0
    between 20 and 42 weeks gestation,
  • Ranges between 15.8 and 30.
  • Single, double, triple, quadruple loops at
    10.6, 2.5, 0.5 and 0.1, respectively (Br J
  • Single, double, triple loops at 21.7, 1.7, and
    0.3 (J Fam Prac 1992).
  • Nuchal cords may reduce spontaneously.

Perinatal Outcome (1)
  • Unclear whether or not nuchal cords are
    associated with increased adverse perinatal
  • Associated with neonatal shock and anemia.
  • Increased incidence of intrapartum fetal

Perinatal Outcome (2)
  • Fetuses with nuchal cords were associated with a
    significantly increased prevalence of variable
    decelerations of the FHR versus matched controls
    in both the first and second stages of labor.
  • Umbilical artery pH, 7.25 vs. 7.27 (Plt.05).
  • Umbilical artery acidemia usually mixed (68) or
    respiratory in origin (23).
  • Metabolic acidemia was infrequent (9).
  • (Hankins GV et al, Obstet Gynecol

Perinatal Outcome (3)
  • Retrospective, case control study of 167 infants
    with nuchal cords vs. 523 controls.
  • Fetal bradycardia and variable decelerations
    occurred significant more often in the nuchal
    cord group (18.6 vs. 9.6).
  • No significant differences in operative
    deliveries or 1, 5 minute Apgar scores.
  • Neonates with nuchal cords weighed significantly
    less than controls.
  • (Miser et al, J Fam Prac 199234441-4)

Perinatal Outcome (4)
  • Compared with single or no cord entanglement,
    pregnancies with multiple nuchal cords were more
    likely to have
  • Meconium-stained amniotic fluid
  • Intrapartum fetal heart rate changes
  • Operative vaginal delivery
  • Low 1 minute Apgar scores
  • Mild umbilical artery acidosis at birth
  • (Larson et al, Am J Obstet Gynecol

Perinatal Outcome (5)
  • Among 70 women delivering infants with nuchal
    cords, there were significantly increased
    incidences of
  • Meconium-stained amniotic fluid
  • Severe intrapartum variable decelerations
  • Fetal bradycardia
  • These authors suggested that in the presence of
    oligohydramnios, nuchal cord might represent an
    increased risk of intrapartum FHR changes.
  • (Strong et al, J Reprod Med 199237718-20)

Perinatal Outcome (6)
  • Although it is extremely difficult to prove
    causality, nuchal cord(s) have been implemented
    in occurrences of intrauterine fetal death.

Previous Diagnostic Modalities
  • Spontaneous testing
  • Increased incidence of variable FHR decelerations
    (3 episodes, 15 bpm, lasting 15 sec).
  • Double or W pattern of FHR.
  • Evoked testing
  • Recording FHR following manual transabdominal
    compression of fetal neck (82.3 sensitivity and
    89.1 specificity).
  • FHR decelerations following vibroacoustic

Ultrasonography of the Umbilical Cord
  • Traditionally not performed uniformly due to
  • Objective difficulty (2D depiction of free
    floating narrow structure in 3D environment).
  • Fetal movement
  • Lack of immediate availability of color Doppler
  • Lack of institutional guidelines.
  • Dependent on determination of sonographer.

Ultrasonography of the umbilical cord
  • The umbilical cord exhibits coiling (helical
  • Fetuses with non-coiled umbilical cords are at
    increased risk for adverse perinatal outcome.
  • Nuchal cords, have less vascular coiling.
  • Potentially, the coiled umbilical cord may be
    able to withstand vascular stretching and
    compression associated with nuchal entanglement.

Ultrasonography of nuchal cords
  • Requires a high-degree of suspicion (due to the
    sonolucent nature of umbilical vessels).
  • Represents a fixed point of the umbilical cord,
    specifically in the vicinity of the fetal neck.
  • Become significantly easier with high-resolution
    ultrasound with the divot sign representing
    circular indentations of the fetal nuchal skin
    (Ranzini et al, Obstet Gynecol 199993854).
  • Care should be excercised not to confuse
    posterior cystic masses, folds of skin or
    amniotic fluid pockets, with the divot sign.

Ultrasonography of Nuchal Cords
  • The condition renders itself to color Doppler
  • Both sagittal and axial sections (cross-section
    and linear, respectively) are required to avoid
  • Doppler flow velocimetry may be applied to
    confirm diagnosis.
  • 3D ultrasound may improve prenatal diagnosis.

Color Doppler Ultrasound of Nuchal Cord
  • Color Doppler imaging correctly identifies 72 of
    single, and 94 of multiple nuchal cords found at
  • Overall sensitivity of color Doppler ultrasound
    in the prenatal detection of nuchal cords is 79.
  • Greater sensitivity noted after, rather than
    before 36 weeks gestation (93 vs. 67),
    possibly reflecting spontaneous reduction with
    earlier diagnosis.
  • (Jauniaux et al, Ultrasound Obstet Gynecol

Color Doppler Ultrasound of Nuchal Cord
  • Reported sensitivity and specificity of
    intrapartum color Doppler ultrasound diagnosis of
    nuchal cord, 96 and 97, respectively.
  • (Funk et al, Geburtshilfe Frauenheilkd
  • (Qin et al, Ultrasound Obstet Gynecol
  • 3D surface imaging does not provide more useful
    information than conventional 2D or color Doppler
    ultrasound in detecting nuchal cords.
  • (Hanaoka et al, Ultrasound Obstet Gynecol

Single Nuchal Cord(sagittal view)
Single Nuchal Cord(color Doppler, sagittal view)
Single Nuchal Cord (color Doppler, axial view)
Single Nuchal Cord(color Doppler, axial view)
Single Nuchal Cord (color Doppler, axial view)
Double Nuchal Cord (sagittal view)
Double Nuchal Cord(color Doppler, sagittal view)
Double Nuchal Cord(color Doppler, axial view)
Double Nuchal Cord (color Doppler, axial view)
Doppler Flow Velocimetry of Nuchal Cord
  • Abnormal Doppler flow waveforms suggesting an
    obstruction to flow have been reported in
    association with true knots of the cord.
  • Potential waveform abnormalities include
  • systolic notching of the umbilical artery
  • poststenotic acceleration of umbilical vein flow.
  • absent end diastolic flow (reported with nuchal

Doppler Velocimetry of Nuchal Cord
Doppler Velocimetry ofNuchal Cord
Doppler Velocimetry ofNuchal Cord
3D UltrasoundSingle Nuchal Cord
3D Ultrasound Double Nuchal Cord
3D UltrasoundTriple Nuchal Cord
Ultrasonography of Nuchal Cords
  • Disregard?
  • dont ask, dont tell
  • Inform?
  • Monitor?
  • Intervene?

Suggested Modified Management
  • Information regarding the presence of nuchal
    cord(s) should not be withheld.
  • Findings should be discussed openly in real-time
    with the patient, preferably by a Perinatologist.
  • Should be explicitly stated on the written report
    generated following US examination.

Patient Counseling, Should Address
  • Reassurance as to the high-probability of
    unaffected outcome.
  • Critical importance of fetal movement assessment.

In addressing Clinical Management
  • Number of involved nuchal loops.
  • Amniotic fluid volume status (AFI).
  • Gestational age.
  • Fetal growth.

Fetal Testing Indicated
  • Significantly decreased amniotic fluid volume.
  • Postdates.
  • Fetal growth restriction.
  • Decreased fetal movements.

Fetal Testing Should Include
  • Nonstress test.
  • Biophysical profile.
  • Doppler flow velocimetry
  • Potentially, evoked tests including
  • Vibroacoustic stimulation
  • Oxytocin challenge test

With less than optimal fetal testing
  • Delivery should be considered

Potentially, application of these new guidelines,
may decrease the occurrence of third-trimester
in-utero fetal demise associated with nuchal
In summaryUltrasonographic depiction of a
nuchal cord should be
  • Recorded in the patients chart.
  • Fowarded to the patient and her physician.
  • Managed with close fetal surveillance including
    fetal movement counts and interval fetal testing.
  • In selected cases, may indicate delivery.
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