Umbilical artery Doppler waveform notching: is it a marker for cord and placental abnormalities?
ABSTRACT To evaluate in a prospective, controlled fashion the prevalence of umbilical artery Doppler waveform notching and its association with cord and placental abnormalities.
During a 6-month period, umbilical artery velocity waveforms were prospectively obtained on 1857 pregnancies at greater than 27 weeks' gestation. All pregnant patients with the presence of a persistent fetal umbilical artery waveform notch formed the study population (cases). Control patients, matched for gestational age, with normal umbilical artery waveforms, were selected for comparison (2 controls per case). After delivery, detailed pathologic examination was performed on all umbilical cords and placentas.
The presence of an umbilical artery waveform notch was noted in 29 (1.6%) of 1857 pregnancies. Postnatal placental evaluation showed the presence of an accessory placental lobe in 5 (17%) of 29 cases compared with 1 (1.8%) of 54 controls (P = .018). Overall, the presence of an umbilical artery waveform notch was associated with umbilical cord abnormalities in 21 (72%) of 29 cases compared with 8 (14%) of 54 controls (odds ratio, 15; 95% confidence interval, 4.4-54.4).
Umbilical artery waveform notching appears to be a strong predictor of cord and placental abnormalities. This finding may have important clinical implications.
- [show abstract] [hide abstract]
ABSTRACT: In order to evaluate the clinical significance of velamentous cord insertion (VCI) and the role of ultrasound in its diagnosis, all 82 cases of VCI during January 1985 to January 1989 at the Mount Sinai Medical Center were reviewed. The overall rate of VCI in our study (0.5%) was similar to that of previous reports. Pregnancy outcomes in VCI patients with 77 singleton gestations were compared with a control group of 15,865 patients. In contrast to the existing literature, multiparity and prior cesarean section deliveries were not increased in pregnancies with VCI. The VCI group had more intrapartum complications and a lower birthweight than the controls. Routine nontargeted obstetric ultrasound failed to detect any cases of VCI, including three cases of vasa previa. Since VCI was not identified prenatally and many of its sequelae are readily identifiable only during the intrapartum period, the potential for preemptive obstetric intervention appears to be limited. In addition, failure to diagnose apparent VCI during a routine ultrasound does not appear to be a departure from the standard of care.American Journal of Perinatology 04/1992; 9(2):123-6. · 1.57 Impact Factor
- Clinical Obstetrics and Gynecology 10/1996; 39(3):571-87. · 1.84 Impact Factor
Umbilical Artery Doppler
Is It a Marker for Cord and
Alfred Abuhamad, MD, Annette J. Sclater, RDMS,
Eric J. Carlson, MD, Richard P. Moriarity, MD,
Maria A. Aguiar, MD
Objective. To evaluate in a prospective, controlled fashion the prevalence of umbilical artery Doppler
waveform notching and its association with cord and placental abnormalities. Methods. During a 6-
month period, umbilical artery velocity waveforms were prospectively obtained on 1857 pregnancies
at greater than 27 weeks’ gestation. All pregnant patients with the presence of a persistent fetal
umbilical artery waveform notch formed the study population (cases). Control patients, matched for
gestational age, with normal umbilical artery waveforms, were selected for comparison (2 controls per
case). After delivery, detailed pathologic examination was performed on all umbilical cords and pla-
centas. Results. The presence of an umbilical artery waveform notch was noted in 29 (1.6%) of 1857
pregnancies. Postnatal placental evaluation showed the presence of an accessory placental lobe in
5 (17%) of 29 cases compared with 1 (1.8%) of 54 controls (P = .018). Overall, the presence of an
umbilical artery waveform notch was associated with umbilical cord abnormalities in 21 (72%) of 29
cases compared with 8 (14%) of 54 controls (odds ratio, 15; 95% confidence interval, 4.4–54.4).
Conclusions. Umbilical artery waveform notching appears to be a strong predictor of cord and pla-
cental abnormalities. This finding may have important clinical implications. Key words: cord abnor-
malities; Doppler imaging; notching; placental abnormalities; umbilical artery.
Received February 25, 2002, from the Departments
of Obstetrics and Gynecology (A.A., A.J.S., E.J.C.)
and Pathology (R.P.M., M.A.A.), Eastern Virginia
Medical School, Norfolk, Virginia. Revision request-
ed April 8, 2002. Revised manuscript accepted for
publication April 17, 2002.
Address correspondence and reprint requests to
Alfred Abuhamad, MD, Division of Maternal-Fetal
Medicine, Hofheimer Hall, Suite 310, 825 Fairfax
Ave, Norfolk, VA 23507.
CI, confidence interval; OR, odds ratio
mbilical cord abnormalities, including
marginal or velamentous cord insertion, cord
stricture, torsion, and knot formation, are
commonly encountered in clinical practice,
and their presence has been associated with fetal mor-
bidity and mortality.1,2Few reports in the literature have
discussed the role of sonography in the prenatal diagno-
sis of cord abnormalities, and the diagnosis of these
abnormalities has been largely limited to postnatal
examination of the cord.
A notch in the umbilical artery Doppler waveform has
been reported previously in association with cord entan-
glement in monoamniotic twins,3,4velamentous cord
insertion with umbilical artery narrowing,5umbilical
artery compression,6and knot formation.7In these case
reports, the presence of umbilical artery waveform
notching was postulated to reflect hemodynamic alter-
ations in association with anatomic narrowing or distor-
tion of the umbilical vessels. The purpose of this study
was to evaluate in a prospective, controlled fashion the
© 2002 by the American Institute of Ultrasound in Medicine • J Ultrasound Med 21:857–860, 2002 • 0278-4297/02/$3.50
prevalence of umbilical artery waveform notch-
ing and its association with cord and placental
Materials and Methods
This study was conducted at the maternal-fetal
medicine unit at Eastern Virginia Medical School
following approval by the Institutional Review
Board. Consent was obtained from all study par-
ticipants. During a 6-month period, pregnant
patients having sonographic examinations at our
unit were invited to participate in this study.
Patients were enrolled in this study if they satis-
fied the following entry criteria: singleton preg-
nancy, gestational age at study entry of greater
than 27 completed weeks, normal fetal growth
and anatomic survey results, absence of mater-
nal metabolic or vascular disease, and planned
delivery at Sentara Norfolk General Hospital.
Gestational age determination was based on the
last menstrual period and confirmed by first- or
second-trimester sonography in all patients.
Doppler examination was performed with the
mother in the semirecumbent position. The fetal
abdomen was imaged in an axial view at the level
of the cord insertion by means of real-time sonog-
raphy with a 3.5- or 5.0-MHz transducer with
color and pulsed Doppler capabilities. Doppler
velocimetric waveforms of the umbilical artery
were obtained from the umbilical cord in its mid-
section between its placental and abdominal
insertion. Color Doppler imaging was used to
optimize placement of the pulsed wave Doppler
gate at the area of maximum blood flow. Pulsed
Doppler evaluation was performed with a sample
volume of 3 mm and a pass filter between 0 and
50 Hz. Umbilical artery Doppler waveforms were
obtained during fetal rest and apnea. Apnea was
defined by the absence of variable changes in the
waveform patterns for more than 10 waveforms.
Measurements for Doppler indices were obtained
from the frozen image, using the software includ-
ed in the sonographic equipment. An umbilical
artery waveform notch was diagnosed when a
notch was seen persistently throughout the
Doppler waveform spectrum (Fig. 1).
All pregnant patients with the presence of a
fetal umbilical artery waveform notch formed
the study population (cases). A control group
was selected, consisting of 2 controls for each
index case, matched for gestational age ± 2
weeks. Control pregnancies were prospectively
selected as the first 2 pregnancies seen in our
ultrasound unit after the index case with normal
umbilical artery waveforms and meeting the
study entry criteria. Prenatal Doppler findings
were not used in clinical management.
Obstetric and neonatal outcome data were
prospectively collected for all cases and controls.
Outcome data included gestational age at deliv-
ery, mode of delivery, indications for surgical
delivery, neonatal birth weight, and umbilical
artery cord pH. After delivery, 2 pathologists
(M.A.A. and R.P .M.) examined all umbilical cords
and placentas. The pathologists were blinded to
the prenatal Doppler findings.
Data analysis was performed with the Student t
test for continuous variables and with the χ2or
Fisher exact test when applicable for nominal
data. Odds ratios (ORs) were calculated, and the
2-tailed P value was used when appropriate.
P < .05 was considered statistically significant.
Umbilical artery Doppler velocimetry was per-
formed on a total of 1857 pregnancies during the
study period. Of these, 29 pregnancies had
umbilical artery waveform notching (cases), for a
prevalence of 1.6% in our population. A total of
58 pregnancies formed the control group. Four
pregnancies from the control group were lost to
follow-up, resulting in a control group of 54 preg-
nancies. None of the umbilical artery Doppler
waveforms had absent or reversed end-diastolic
velocities. One control and none of the cases had
a single umbilical artery.
Table 1 lists maternal demographic characteris-
tics and study entry sonographic findings for
cases and controls. No significant difference was
noted for maternal age, maternal parity, estimat-
ed gestational age, amniotic fluid volume estima-
tion, and umbilical artery systolic-diastolic ratio
at study entry between cases and controls. Table
2 lists the obstetric and neonatal outcomes for
cases and controls. There was no significant dif-
ference in gestational age at delivery, birth
weight, or umbilical artery pH between cases and
controls. More pregnancies with umbilical artery
waveform notching showed evidence of amniot-
ic fluid meconium during labor (9 [31%] of 29
versus 8 [14%] of 54) and resulted in cesarean
delivery (9 [31%] of 21 versus 10 [18%] of 54);
however, these differences did not reach statisti-
cal significance. Indications for cesarean delivery
J Ultrasound Med 21:857–860, 2002
Umbilical Artery Doppler Waveform Notching
differed between the 2 groups; 7 (78%) of 9
women with umbilical artery waveform notch-
ing underwent cesarean deliveries for nonreas-
suring fetal heart rate tracing compared with 2
(20%) of 10 control subjects (OR, 14; 95% confi-
dence interval [CI], 1.1–213.9).
Postnatal placental evaluation noted the
presence of an accessory placental lobe in 5
(17%) of 29 of cases compared with 1 (1.8%) of
54 controls (OR, 11; CI, 1.1–263.9). Further-
more, placental weight at less than the 10th
percentile was more commonly noted in cases
(9 [31%] of 29) when compared with controls (3
[7%] of 54; OR, 7; CI, 1.6–40.2).
Table 3 compares cases and controls with
regard to abnormalities of the umbilical cords.
The presence of marginal and velamentous
cord insertions was more commonly noted in
cases than controls (marginal insertion: cases,
12 [41%] of 29, versus controls, 7 [13%] of 54;
P = .007; velamentous insertion: cases, 4 [14%]
of 29, versus controls, 1 [1.8%] of 54; P = .04).
Umbilical cord strictures, false knots, and true
knots of the cord were exclusively noted in
cases. Overall, the presence of an umbilical
artery waveform notch was associated with
umbilical cord abnormalities in 21 (72%) of 29
cases compared with 8 (14%) of 54 controls (OR,
15; CI, 4.4–54.4).
Doppler velocimetry of the umbilical artery is
commonly used as a test for fetal surveillance in
high-risk pregnancies.8,9The presence of
decreased, absent, or reversed diastolic flow in
the umbilical artery has been correlated with
fetal growth restriction and increased neonatal
morbidity and mortality.8,9Despite a large num-
ber of studies in the literature evaluating the
umbilical artery by Doppler velocimetry, a notch
along the umbilical artery waveform has rarely
been reported. Several case reports have corre-
lated the presence of an umbilical artery wave-
form notch with cord abnormalities or external
cord compression.3–7This study confirms the
association of umbilical artery waveform notch-
ing with placental and umbilical cord abnormal-
ities. An increased prevalence of marginal cord
insertion was also found in our control popula-
tion. This finding may be a reflection of our
referral practice, which primarily comprises
The pathophysiologic mechanism for umbili-
cal artery waveform notching is not clearly
defined. Plausible mechanisms for changes in
blood flow within a vessel that result in a
Doppler waveform notch include distortion, tor-
sion, and compression of that vessel. A computer
model studying the uterine circulation has
shown that severe narrowing will cause an
altered flow velocity waveform pattern with
notching combined with decreased diastolic
flow.10In a previous report, the presence of an
umbilical artery waveform notch was suggested
to result from narrowing of the arterial lumen
with an increase in downstream impedance.3In
that report, increased prominence of the notch
was noted on longitudinal evaluation, which was
attributed to increased narrowing of the umbili-
J Ultrasound Med 21:857–860, 2002
Abuhamad et al
Figure 1. Umbilical artery Doppler velocimetry showing the
presence of a notch at 28 weeks’ gestation.
Table 1. Maternal Demographic Characteristics and Sonographic
Findings at Study Entry for Cases and Controls
DemographicCases (n = 29)Controls (n = 54)P
Maternal age, y*
Primigravida, n (%)
Gestational age, wk*
Amniotic fluid index, cm*
25.2 ± 7.17
34.8 ± 2.74
15.1 ± 6.80
2.57 ± 1.35
23.8 ± 6.82
34.8 ± 2.91
15.7 ± 5.12
2.46 ± 1.32
NS indicates not significant.
*Values are mean ± SD.
cal artery subsequent to cord entanglement in
monoamniotic twins.3Another report in the liter-
ature presented strong evidence for a causal rela-
tionship between umbilical artery waveform
notching and compression of the umbilical cord.6
Herniating fetal stomachs through the abdominal
wall defects in 2 fetuses with gastroschisis caused
umbilical cord compressions at the abdominal
insertion.6The chronologic sequence of events in
these 2 pregnancies clearly showed the temporal
association of umbilical artery waveform notch-
ing with umbilical cord compression.6
Our results confirm that umbilical artery wave-
form notching is associated with cord and pla-
cental abnormalities. This observation is of
considerable clinical importance, given the diffi-
culty involved with the diagnosis of cord and
placental abnormalities on the basis of gray
scale sonography. The presence of an umbilical
artery Doppler waveform notch should there-
fore prompt targeted sonography to look for
cord or placental abnormalities. Doppler flow
velocity of the umbilical artery can also be used
to confirm the presence of suspected cord abnor-
malities such as true or false knots in the cord on
gray scale or color Doppler sonography. Given the
high prevalence of nonreassuring fetal heart rate
abnormalities during labor in our patients with
notches in their umbilical artery Doppler wave-
forms, the presence of this finding should instigate
increased fetal surveillance in these pregnancies.
1. Bernischke K. Obstetrically important lesions of the
umbilical cord. J Reprod Med 1994; 39:262–266.
2. Eddleman KA, Lockwood CJ, Berkowitz GS, Lapinski
RH, Berkowitz RL. Clinical significance and sono-
graphic diagnosis of velamentous umbilical cord
insertion. Am J Perinatol 1992; 9:123–126.
3. Abuhamad AZ, Mari G, Copel JA, Cantwell CJ, Evans
AT. Umbilical artery flow velocity waveforms in
monoamniotic twins with cord entanglement. Obstet
Gynecol 1995; 86:674–677.
4.Kofinas AD, Penry M, Hatjis CG. Umbilical vessel flow
velocity waveforms in cord entanglement in a
monoamniotic multiple gestation. J Reprod Med
5.Robinson JN, Abuhamad AZ, Sayed A, Evans AT.
Umbilical artery Doppler velocimetry waveform
notching and umbilical cord abnormalities.
J Ultrasound Med 1997; 16:373–375.
6.Robinson JN, Abuhamad AZ, Evans AT. Umbilical
artery Doppler velocimetry waveform abnormality in
fetal gastroschisis. Ultrasound Obstet Gynecol 1997;
7. Jakobi P, Weiner Z, Goren T, et al. Systolic notch in
umbilical artery flow velocity waveforms associated
with a tight true knot of the cord. J Matern Fetal
Investig 1994; 4:119–121.
8. Zarko A, Neilson JP. Doppler ultrasonography in high-
risk pregnancies: systematic review with meta-analy-
sis. Am J Obstet Gynecol 1995; 172:1379–1387.
9.Pattison RC, Odendaal HJ, Kirsten G. The relationship
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JW. Effect of placental resistance, arterial diameter
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computer modeling approach. Ultrasound Med Biol
J Ultrasound Med 21:857–860, 2002
Umbilical Artery Doppler Waveform Notching
Table 2. Obstetric and Neonatal Outcome for Cases and Controls
Outcome Measure Cases ControlsP
Gestational age at delivery, wk*
Birth weight, g*
Meconium, n (%)
Cesarean delivery, n (%)
Cesarean delivery for NRFHT, n (%)
38.4 ± 1.93
3109 ± 618.3
7.20 ± 0.08
39.5 ± 1.33
3343 ± 586.5
7.24 ± 0.07
NRFHT indicates nonreassuring fetal heart rate tracing; and NS, not significant.
*Values are mean ± SD.
Table 3. Umbilical Cord Abnormalities for Cases and Controls
(n = 29)
(n = 54)AbnormalityP
Marginal insertion of cord, n (%)
Velamentous insertion of cord, n (%)
Cord stricture, n (%)
False knot in cord, n (%)
True knot in cord, n (%)
Total, n (%)