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Diagnosis of Umbilical Cord Entanglement of Monoamniotic Twins .pdf


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									                                                                                                            Case Report

Diagnosis of Umbilical Cord
Entanglement of Monoamniotic
Twins by First-Trimester
Color Doppler Imaging

                                  David M. Sherer, MD, Margarita Sokolovski, RDMS,
                                  Nathan Haratz-Rubinstein, MD

                                                  onoamniotic twins occur in approximately 5% of monochorionic twin
                                                  gestations as a result of splitting of the inner cell mass at 8 or more days
                                                  after fertilization, and they are associated with high perinatal mortality
                                                  rates, ranging between 28% and 47%.1,2 These gestations have unique
                                  pathologic conditions, including conjoined twins, a high prevalence of discordancy
                                  for fetal structural anomalies (the former and possibly also the latter resulting from
                                  consequences of the twinning process), and cord entanglement.1
                                    We present a case in which monoamniotic twins at first-trimester transvaginal sonog-
                                  raphy were confirmed by color Doppler imaging as having entangled umbilical cords.

                                                                 Case Report

                                                                 A multiparous patient underwent dating sonography at
                                                                 10 weeks’ gestation. Her medical history was notable for
                                                                 chronic renal failure of undetermined etiology, and she
                                                                 had been undergoing hemodialysis 6 times weekly for the
                                                                 past 5 years. The patient denied hypertension and was
                                                                 not taking any medication. She had 2 previous uncom-
                                                                 plicated pregnancies, each with spontaneous term deliv-
                                                                 ery of appropriate-for-gestational-age infants, the most
                                                                 recent while she was undergoing hemodialysis.
Received July 8, 2002, from the Division of                        Transvaginal sonography revealed a viable twin gesta-
Maternal-Fetal Medicine, Department of Obstetrics
and Gynecology, State University of New York,                    tion. A single yolk sac was present, and no intertwin
Downstate Medical Center, Brooklyn, New York.                    membrane was depicted. Thus the pregnancy was con-
Revision requested July 10, 2002. Revised manu-                  sidered a monoamniotic twin gestation. Crown-rump
script accepted for publication July 24, 2002.
    Address correspondence and reprint requests to               lengths were concordant and appropriate for gestational
David M. Sherer, MD, Division of Maternal-Fetal                  age (both 30 mm, equal to 9 weeks 6 days). The fetuses
Medicine, Department of Obstetrics and Gyne-                     were facing each other in extremely close proximity, with
cology, State University of New York, Downstate
Medical Center, 450 Clarkson Ave, Box 24,                        the correlating fetal poles exactly opposite each other,
Brooklyn, NY 11203-2098.                                         respectively. Initially, conjoined twins and umbilical cord

   © 2002 by the American Institute of Ultrasound in Medicine • J Ultrasound Med 21:1307–1309, 2002 • 0278-4297/02/$3.50
Umbilical Cord Entanglement of Monoamniotic Twins

                 entanglement were considered possible causes of                       Second- and third-trimester prenatal sono-
                 the unusual fetal positioning. Follow-up trans-                     graphic diagnosis of entangled monoamniotic
                 vaginal sonography at 12 weeks’ gestation showed                    twins was initially reported by Belfort et al,5 who
                 viable twins. Color Doppler imaging depicted                        described apparent branching of the umbilical
                 “branching” of the umbilical artery indicative of                   artery in 3 such cases. Other indirect sonograph-
                 umbilical cord entanglement (Fig. 1). The twins                     ic findings include abnormalities on Doppler
                 appeared anatomically intact, with no sonograph-                    flow velocimetry reflecting hemodynamic alter-
                 ic signs of cardiac failure. The patient was coun-                  ations in the fetal-placental circulation sec-
                 seled as to the potential poor prognosis of this                    ondary to narrowing of the umbilical vessels
                 condition and elected to continue the pregnancy.                    involved in cord entanglement, such as a “notch”
                 Treatment with sulindac (a nonsteroidal anti-                       in the umbilical artery waveform.6,7 Previously
                 inflammatory medication), as a measure to limit                     reported first-trimester diagnoses of cord-
                 further entanglement by inducing decreased                          entangled monoamniotic twins also have
                 amniotic volume, was considered although not                        included case-dependent Doppler flow velo-
                 initiated.1 Follow-up examination at 14 weeks dis-                  cimetry findings such as differing fetal heart rate
                 closed fetal death of the twins. The patient under-                 patterns within a common mass of cord vessels
                 went dilation and evacuation, at which time                         and “galloping” heart rates (in which 2 distinct
                 entangled umbilical cords were confirmed.                           arterial flow velocity waveforms are depicted in
                                                                                     the same channel at insonation of the cord
                 Discussion                                                          mass).4,8 Such early prenatal diagnoses of cord
                                                                                     entanglement led Overton et al4 in 1999 to sug-
                 Widespread application of first-trimester trans-                    gest that the branching sign is unlikely to be
                 vaginal sonography has enabled precise depic-                       applicable during the first half of pregnancy,
                 tion of chorionicity and amnionicity in multiple                    when the cord vessels are too small for individu-
                 gestations.3 As a result, previously undetermined                   al visualization.
                 prevalence rates of conditions such as conjoined                      In contrast, our case confirms that first-
                 twins and cord entanglement unique to mono-                         trimester color Doppler imaging alone may suf-
                 amniotic gestations, each with high (and early)                     fice in the diagnosis of cord entanglement of
                 intrauterine loss rates, are now becoming avail-                    monoamniotic twins without necessitating
                 able.1,4 Currently, the prevalence of umbilical                     application of Doppler flow velocimetry in the
                 cord entanglement has been estimated at                             attempt to depict subtle hemodynamic abnor-
                 between 70% and 91% of cases.1,4                                    malities. Furthermore, this case also emphasizes
                                                                                     that at first-trimester sonography, in addition to
                                                                                     conjoined twins, umbilical cord entanglement
Figure 1. Transvaginal sonogram with color Doppler flow imaging at 12 weeks’
gestation. The lower poles of the fetal bodies are located at the top. The respec-   should be considered in the differential diagnosis
tive chests, upper extremities, and heads are located at the bottom, out of the      of closely approximated twins.
focal zone and hence blurred. Note the close proximity of the monoamniotic twins.
The arrow points to the branching of the umbilical artery.                           References

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1308                                                                                                J Ultrasound Med 21:1307–1309, 2002
                                                             Sherer et al

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J Ultrasound Med 21:1307–1309, 2002                                 1309

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