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ANSWERS
CASE 17
Myelomeningocele
1. A, B, C, and D
2. B
3. A
4. C
References
Kim SY, McGahan JP, Boggan JE, et al: Prenatal diagnosis of lipomyelo-
meningocele. J Ultrasound Med 2000; 19(11):801-805.
http://www.ncbi.nlm.nih.gov/pubmed/11065270 (Accessed on June 4,
2012.)
McGahan JP, Pilu G, Nyberg DA: Neuro tube defect and spine. In Nyberg
DA, McGahan JP, Pretorius DH, et al. (eds): Diagnostic Imaging of Fetal
Anomalies, Philadelphia, Lippincott Williams & Wilkins, 2003, pp 230-334.
Nicolaides KH, Campbell S, Gabbe SG: Ultrasound screening for spina
bida: cranial and cerebellar signs. Lancet 1986 2(8498):72-74.
http://www.ncbi.nlm.nih.gov/pubmed/2425202 (Accessed on June 4, 2012.)
Cross-Reference
Ultrasound: The REQUISITES, 2nd ed, pp 402-406.
Comment
Differential Diagnosis
The differential diagnosis for lumbosacral masses is discussed
in Case 10: Sacrococcygeal Teratoma. The case here is an open
neural tube defect in which there may be a cystic complex or
solid mass originating from the lumbosacral spine. Associated
cranial defects are present as shown by the lemon and banana
signs (Figures A and B). There is associated ventriculomegaly in a high percentage of cases. Other entities that may be
considered include amniotic band syndrome and limb–body
wall complex. In both of these entities, asymmetric defects
and scoliosis are associated with disruption of the amnion.
In limb–body wall complex, there is continuity of the fetus
with the placenta surface. Finally, sacrococcygeal teratoma may
manifest as either a cystic complex or a solid mass originating from the coccyx and could be considered in the differential diagnosis. Rare tumors such as lipoma of the cord or
other cutaneous tumors may be considered in the differential
diagnosis. However, none of these is usually associated with a
lemon sign or banana sign.
Ultrasound Features
Ultrasound features of myelomeningocele, or spina bida,
include a lumbosacral mass that is complex cystic or solid. The
neural foramen is splayed (Figure C). The spinal cord is tethered or lies within the sacral region. There is an association of
a posterior deformity in which the cerebellum is displaced into
the cisterna magna and becomes effaced; this results in a cerebellum having the appearance of a banana (Figure B). Before
24 weeks’ gestation, the cranium may have a lemon shape, in
which the frontal bone is scalloped (Figure A). The lemon sign
suggests the possibility of spina bida, but it is not pathognomonic for spina bida. It rarely can be seen in normal fetuses,
fetuses with trisomy 18, and fetuses with an encephalocele.
Careful scanning of the rest of the fetus is needed. If a myelomeningocele is present, it may be associated with ventriculomegaly in the late second trimester in 70% to 80% of cases.
Ventriculomegaly can be present at birth in 90% of cases.
Prognosis and Management
Even with appropriate diagnosis and treatment, a very high
infant mortality rate is associated with spina bida. Approximately 20% of live-born infants undergoing surgery die within
the rst year of life. Approximately one third of all infants die
within the rst 5 years. Death is usually related to respiratory
failure, although there may be other etiologies. Individuals who
survive often have lower limb dysfunction and problems with
urinary incontinence.
36
CASE 18
A
Used with permission from Towner D, McGahan J, Rhee-Morris L, et al:
The dynamic fetal brain. J Clin Ultrasound 35(5):238-244, 2007.
B
History: A patient presents with a third-trimester ultrasound
scan that was performed at an outside institution and that
shows increased intracranial uid.
1. What should be included in the differential diagnosis?
(Choose all that apply.)
A. Hydranencephaly
B. Alobar holoprosencephaly
C. Aqueductal stenosis
D. Arnold-Chiari malformation
E. Dandy-Walker malformation
2. Which of the following is not a cause of ventriculomegaly?
A. Infectious causes
B. Chromosomal abnormalities
C. Hydranencephaly
D. In utero intraventricular hemorrhage
C
3. All of the following ndings are associated with X-linked
hydrocephalus except:
A. Abduction of the thumb
B. Abnormal facies
C. Absence of septum pellucidum
D. Associated with female fetuses
4. Which of the following should not be included in the
management of fetuses with hydrocephalus?
A. Careful ultrasound scan to rule out associated anomalies
B. Perform fetal karyotyping
C. Consider workup for in utero infection
D. Cesarean section should always be considered
37
ANSWERS
CASE 18
Aqueductal Stenosis
1. C, D, and E
anomalies. Hydranencephaly is usually associated with lack of
cerebral tissues, unfused thalami, and a midline falx.
2. C
3. D
4. D
References
Pilu G, Falco P, Gabrielli S, et al: The clinical signicance of fetal isolated
cerebral borderline ventriculomegaly: report of 31 cases and review of the
literature. Ultrasound Obstet Gynecol 1999; 14(5):320-326.
http://www.ncbi.nlm.nih.gov/pubmed/10623991 (Accessed on June 4,
2012.)
Silan F, Ozdemir I, Lissens W: A novel L1CAM mutation with L1 spectrum
disorders. Prenat Diagn 2005; 25(1):57-59.
http://www.ncbi.nlm.nih.gov/pubmed/15662685 (Accessed on June 4,
2012.)
Towner D, McGahan J, Rhee-Morris L, et al: The dynamic fetal brain. J Clin
Ultrasound 2007; 35(5):238-244.
http://www.ncbi.nlm.nih.gov/pubmed/17410587 (Accessed on June 4, 2012.)
Cross-Reference
Ultrasound: The REQUISITES, 2nd ed, pp 402-406, 410.
Comment
Differential Diagnosis
The differential diagnosis depends on whether ventriculomegaly is mild (ventricular size between 10 and 15 mm) or
moderate to severe (ventricular size >15 mm). Any etiology
of ventriculomegaly could be considered, including ArnoldChiari malformation and Dandy-Walker malformation.
Arnold-Chiari malformation has a lemon sign. Dandy-Walker
malformation has a posterior fossa cyst. However, there are
usually associated ndings that are easily recognized in these
entities. Intracranial hemorrhage and infections may cause in
utero hydrocephalus. Anomalies such as alobar holoprosencephaly or hydranencephaly may cause massive cerebrospinal
uid collection, but there are features that distinguish them
from hydrocephalus. Alobar holoprosencephaly is associated
with a monoventricular cavity with fused thalami and facial
Ultrasound Findings
Ventriculomegaly usually refers to dilation of the lateral ventricles. The upper limit of normal of the trigone of the lateral
ventricle is 10 mm. Dilation greater than 10 mm is referred
to as ventriculomegaly. It has been shown that the amount of
ventriculomegaly affects prognosis. Mild ventriculomegaly has
a much better prognosis than massive ventriculomegaly.
Aqueductal stenosis refers to obstruction of the aqueduct
of Sylvius. There is dilation of the third ventricle and lateral
ventricles. The ventricular size may be normal in the early
second trimester, but massive ventriculomegaly may develop
later in the second trimester and in the early third trimester. A
workup for other intracranial anomalies is important because
the ventriculomegaly may be secondary to Arnold-Chiari type
II malformation or Dandy-Walker malformation. The features
of these anomalies are readily apparent on ultrasound (Figures
A and B). MRI can also show ventriculomegaly (Figure C).
X-linked hydrocephalus is associated with aqueductal stenosis. Demonstration on ultrasound of abduction of thumbs in
combination with ventriculomegaly should strongly suggest
the diagnosis of X-linked hydrocephalus.
Prognosis and Management
Amniocentesis may be suggested to exclude chromosomal
abnormalities. TORCH (toxoplasmosis, other agents, rubella,
cytomegalovirus, herpes simplex) titers may be necessary to
exclude infectious etiologies of ventriculomegaly. Frequent
ultrasound scans are needed because ventriculomegaly is very
dynamic, and ventricular size can change with time. Delivery
can be vaginal unless there is associated ventriculomegaly,
which would cause increased head size that might prevent
vaginal delivery. In these cases, cesarean section may be necessary. Cephalocentesis and in utero shunt placement have been
abandoned in the United States. However, after delivery, intracranial shunt procedures may be necessary.
38
CASE 19
A
History: A patient undergoes routine second-trimester
ultrasound.
1. What should be included in the differential diagnosis in Figure A? (Choose all that apply.)
A. Omphalocele
B. Gastroschisis
C. Limb–body wall complex
D. Meningomyelocele
E. Ectopia cordis
2. What is a key feature of omphalocele on prenatal
ultrasound?
A. Free-oating small bowel arising lateral to cord insertion
B. Umbilical cord inserting on membrane-covered ventral
abdominal wall defect containing bowel and liver
C. Complex mass arising from lateral abdominal wall with
multiple limb and spinal anomalies
D. Midline infraumbilical soft tissue mass with absence of
uid-lled bladder and splayed pubic bone
3. Which of the following entities is not associated with
increased incidence of omphalocele?
A. Beckwith-Wiedemann syndrome
B. Maternal folic acid supplements
C. Pentalogy of Cantrell
D. Chromosomal abnormalities
B
Used with permission from Anderson Publishing Ltd., from Victoria T,
et al: Fetal MRI of common non-CNS abnormalities: a review. Appl
Radiol 40(6)8-17, 2011. © Anderson Publishing Ltd.
4. When is the best time to diagnose omphalocele on prenatal
ultrasound?
A. After 8 weeks
B. After 14 weeks
C. After 30 weeks
D. At any time during gestation
39
ANSWERS
CASE 19
Omphalocele
1. A, B, and C
2. B
anus, spinal defects) complex. There is a high association with
chromosomal abnormalities, most notably trisomies 18 and 13.
A cardiac malformation is present in 50% of neonates with
omphalocele.
3. B
4. B
References
Blazer S, Zimmer EZ, Gover A, et al: Fetal omphalocele detected early
in pregnancy: associated anomalies and outcomes. Radiology 2004;
232(1):191-195.
http://www.ncbi.nlm.nih.gov/pubmed/15220502 (Accessed on June 5,
2012.)
Fogata ML, Collins HB II, Wagner CW, et al: Prenatal diagnosis of compli-
cated abdominal wall defects. Curr Probl Diagn Radiol 1999; 28(4):101-128.
http://www.ncbi.nlm.nih.gov/pubmed/10403093 (Accessed on June 5,
2012.)
Mann S, Blinman TA, Douglas Wilson R: Prenatal and postnatal manage-
ment of omphalocele. Prenat Diagn 2008; 28(7):626-632.
http://www.ncbi.nlm.nih.gov/pubmed/18634119 (Accessed on June 5,
2012.)
Cross-Reference
Ultrasound: The REQUISITES, 2nd ed, pp 443-447.
Comment
Differential Diagnosis
The differential diagnosis for omphalocele includes gastroschisis, amniotic band syndrome, and limb–body wall complex.
Keys to differentiating these entities include location of the
defect with respect to the umbilical cord and umbilical cord
insertion site, presence of a membrane, hernia contents, and
associated abnormalities. All entities in the differential diagnosis may have elevated alpha-fetoprotein. Omphalocele is
the most common abdominal wall defect, occurring in 1:4000
live births. Although most commonly sporadic in occurrence,
omphalocele may be associated with other syndromes, including Beckwith-Wiedemann syndrome, pentalogy of Cantrell,
and OEIS (omphalocele, exstrophy of bladder, imperforate
Ultrasound Findings
Omphalocele is characterized by a membrane-covered central
abdominal wall defect containing variable viscera, including
bowel or liver or both (Figures A and B). The umbilical cord
inserts directly onto the herniated sac. On ultrasound, omphalocele can be differentiated from gastroschisis, which has no
membrane and typically arises to the right lateral aspect of the
umbilical cord. Limb–body wall complex and amniotic band
syndrome is an abdominal wall defect with craniofacial and
limb abnormalities. In neonates with omphalocele, thorough
evaluation for associated abnormalities is indicated, including ectopia cordis or other cardiac malformation and bladder or cloacal exstrophy. Diagnosis should be made after 14
weeks’ gestation to avoid confusion with physiologic midgut
herniation.
Prognosis and Management
Outcomes are best for isolated omphaloceles in neonates with
normal karyotypes. Spontaneous resolution of small defects
has been described and may represent the delayed return of
abdominal contents from physiologic midgut herniation. A
20% risk of fetal demise has been described in neonates with
giant omphaloceles. Smaller defects (<5 cm) can be managed
surgically with a single procedure; larger defects may require
a staged approach. There is increased risk of chromosomal
abnormalities with defects of the small bowel only. If there
is no associated chromosomal abnormality, larger defects,
because of size, are more difcult to repair.
Acknowledgment
Special thanks are extended to Alex Fodor, MD, for his contribution to the preparation of this case.
40
CASE 20
History: A patient with a rst-trimester pregnancy under-
goes ultrasound.
1. What should be included in the differential diagnosis?
(Choose all that apply.)
A. Septate uterus with a pregnancy in the right horn
B. Bicornuate uterus with a pregnancy in the right horn
C. Didelphys uterus with a pregnancy in the right horn
D. Blighted ovum in the right horn
2. Which uterine anomaly has the highest incidence of reproductive dysfunction?
A. Bicornuate uterus
B. Uterine didelphys
C. Septate uterus
D. Unicornuate uterus
A
3. Which uterine anomalies are most commonly associated
with second- or third-trimester pregnancy loss?
A. Uterine didelphys
B. Septate uterus
C. Bicornuate uterus
D. Unicornuate uterus
4. Which uterine anomaly has an increased risk of cervical
and vaginal neoplasms?
A. Diethylstilbestrol (DES)-related anomalies of a
T-shaped uterus with a small uterine cavity and cervical
constrictions
B. DES-related anomalies with a large uterine cavity and
cervical constrictions
C. Septate uterus
D. Unicornuate uterus
B
41
ANSWERS
CASE 20
Congenital Uterine Anomalies and Pregnancy
1. A, B, and D
sis and predispose a woman to ectopic or rudimentary horn
pregnancies.
2. C
3. C
4. A
References
Khati NJ, Frazier AA, Brindle KA: The unicornuate uterus and its variants.
J Ultrasound Med 2012; (31)319-331.
http://www.ncbi.nlm.nih.gov/pubmed/22298877 (Accessed on July 6,
2012.)
O’Neill MJ, Yoder IC, Connolly SA, et al: Imaging evaluation and classica-
tion of developmental anomalies of the female reproductive system with
an emphasis on MR imaging. AJR Am J Roentgenol 1999; 173(2):407-416.
http://www.ncbi.nlm.nih.gov/pubmed/10430146 (Accessed on June 5,
2012.)
Wagner BJ, Woodward PJ: Magnetic resonance evaluation of congenital
uterine anomalies. Semin Ultrasound CT MR 1994; 15(1):4-17.
http://www.ncbi.nlm.nih.gov/pubmed/8179942 Accessed on June 5, 2012.)
Cross-Reference
Ultrasound: The REQUISITES, 2nd ed, pp 536-538.
Comment
Müllerian Duct Anomalies
A large study of fertile and infertile women showed that the
most common müllerian duct anomaly is septate uterus (55%).
Other müllerian duct anomalies include bicornuate uterus
(10%), didelphic uterus (11%), arcuate uterus (7%), unicornuate uterus (20%), and hypoplastic uterus (5% to 10%). All
have a higher incidence of renal anomalies, including unilateral
agenesis and ptosis.
Reproductive Difficulties
Uterine anomalies occur more frequently in infertile women.
Depending on the congenital anomaly, women may have difculty with conception, early pregnancy loss, or later complications such as intrauterine growth restriction (IUGR). Septate
uterus results in the highest incidence of reproductive difculties (67%). It is important if a unicornuate uterus is isolated or
with a rudimentary horn. Patients with an isolated unicornuate uterus are usually asymptomatic; however, the small uterine cavity can result in early abortions or premature delivery.
Rudimentary horns can cause chronic pain from endometrio-
Special Problems with a Septate Uterus
Problems with conception may occur with septate uterus.
Problems may be caused by implantation on the septum,
which has an abnormal blood supply. Early pregnancy loss
also occurs. Other anomalies that have an increased incidence
of early pregnancy loss include a unicornuate uterus with a
rudimentary horn and DES-related anomalies.
Present Case
This case shows a pregnancy in the right horn of a bicornuate uterus (Figures A and B). Pregnancy loss occurs more
frequently with a bicornuate uterus than with a uterine didelphys or a unicornuate uterus. Pregnancy loss can occur in the
rst 20 weeks or later in the second or third trimester. Threedimensional ultrasound has been used to evaluate uterine
malformations, especially when there have been inconsistent
results from other imaging modalities, and to locate fetuses
more precisely in the uterine horns.
Diethylstilbestrol during Pregnancy
Women whose mothers used DES during pregnancy can have
T-shaped uterus or uterine cavity constrictions that are not
a
amenable to surgical correction. In addition, they have an
increased risk of cervical and vaginal malignancies, specically
mesonephric clear cell carcinoma of the cervix and vagina.
There are no genitourinary anomalies associated with DESrelated uterine malformations.
Modalities to Diagnose Congenital Uterine
Anomalies
Ultrasound and MRI are the best modalities to diagnose a congenital uterine anomaly; the external uterine fundal contour is
of key importance. The signal intensity of the tissue separating
the two endometrial cavities on MRI can be similar in both
entities. In most septate uteri, the inferior portion of the septum is uniformly dark on T2. The signal intensity of the upper
portion of the septum is similar to the signal intensity of the
myometrium in many patients.
42
CASE 21
A
B
History: A patient with a rst-trimester pregnancy presents
with a right adnexal mass.
1. What should be included in differential diagnosis of a cystic mass lateral to the uterus found in the rst trimester of
pregnancy? (Choose all that apply.)
A. Hemorrhagic cyst
B. Ectopic pregnancy
C. Cystic teratoma
D. Benign or malignant ovarian neoplasm
2. What is the diagnosis for the right adnexal mass seen in
Figures B to D?
A. Dermoid
B. Endometrioma
C. Corpus luteum cyst
D. Ovarian luteoma
C
D
3. In the rst trimester of pregnancy, which of the following
is not a solid mass that can be seen in the adnexa?
A. Pedunculated exophytic broid
B. Ovarian torsion
C. Pelvic kidney
D. Endometrioma
4. If it is necessary to remove an extrauterine mass in a pregnant woman, what is the best time for surgery?
A. After 1 month of pregnancy
B. After the fourth month of pregnancy
C. At term
D. At 8 months
43
ANSWERS
CASE 21
Normal First-Trimester Uterine Pregnancy
with Extrauterine Cystic Teratoma (Dermoid)
1. A, B, C, and D
2. A
3. D
4. B
References
Choi RJ, Levine D, Finberg H: Luteoma of pregnancy: sonographic ndings
in two cases. J Ultrasound Med 2000; 19(12):877-881.
http://www.ncbi.nlm.nih.gov/pubmed/11127014 (Accessed on June 5,
2012.)
Di Salvo DN: Sonographic imaging of maternal complications of pregnancy.
J Ultrasound Med 2003; 22(1):69-89.
http://www.ncbi.nlm.nih.gov/pubmed/12523613 (Accessed on June 5,
2012.)
Eastman NJ, Helman LM (eds): Williams Obstetrics, 13th ed. Stamford, CT,
Appleton Century Crofts, 1966, pp 909-919.
Cross-Reference
Ultrasound: The REQUISITES, 2nd ed, pp 568-584.
Comment
Extrauterine Masses Associated with Pregnancy
Extrauterine masses associated with pregnancy can be
detected by both transabdominal and transvaginal ultrasound
examinations. These masses are commonly an incidental nding, although occasionally the physical examination may suggest the abnormality. Extrauterine masses are usually ovarian
in origin. When cystic, they may be a corpus luteum cyst or
nonfunctioning ovarian cyst. If complex, they can be a hemorrhagic cyst, cystic teratoma, or neoplasm (cystadenomas and
cystadenocarcinomas). Although endometriomas are often
associated with infertility, they may be seen after pregnancy and
can be extraovarian or, less commonly, ovarian. Solid masses
are often exophytic broids, solid benign ovarian masses, ovarian carcinoma, or a pelvic kidney. Ovarian luteomas are rare,
nonneoplastic, usually solid masses that regress spontaneously
after delivery. Abscesses can vary in their appearance and typically are accompanied by signicant symptoms. A hydrosalpinx
appears tubular, especially on a transvaginal study. Ovarian torsion is more often solid and related to pain. Although usually associated with a lead mass, necrosis tends to produce an
amorphous solid appearance.
pregnancy (Figures A to D). The mass is well circumscribed
with hyperechoic areas and low-level or ne linear echoes.
Complications of Ovarian Tumors during
Pregnancy
Ovarian tumors may cause complications during pregnancy.
These tumors are associated with the increased possibility of
a spontaneous abortion; they may undergo torsion, and they
may pose obstacles to vaginal delivery. The second trimester is
generally the best time for exploration of worrisome adnexal
masses because the risk of spontaneous abortion is highest in
the rst trimester, and in the third trimester the risk of preterm
labor is highest. Even after spontaneous labor, the tumors may
cause disturbances in the postpartum period. Although all types
of ovarian tumors may complicate pregnancy and delivery,
most of them are cystic. Their occurrence is 1 in 81 pregnancies; however, tumors that are of sufcient size to constitute
a hazard to pregnancy are considered to have an incidence of
only 1 in 328. Dermoids have been described comparatively
frequently. The most frequent and serious complication of
ovarian cystic masses is torsion, which frequently occurs after
9 weeks’ gestation. The cysts may rupture and extrude their
contents into the peritoneal cavity during spontaneous labor
or as a result of operative interference. If the tumor blocks the
pelvis, it can rupture the uterus or be forced into the vagina
and occasionally even into the rectum.
Treatment of Ovarian Tumors during Pregnancy
Many ovarian tumors complicating pregnancy are asymptomatic and unsuspected. Ultrasound can detect extrauterine
tumors, particularly smaller ones that may not cause many of
these complications. However, if these tumors are clinically
considered to be large enough to cause problems (usually >4
to 5 cm), they should be removed. There is a pregnancy loss
rate from surgery, and it is thought that the early to middle
second trimester (after the fourth month of pregnancy) is the
most opportune time for removal of these masses. Although
there is still a chance that the operation may lead to a spontaneous abortion, the danger is minimal compared with possible
torsion or rupture of the cyst or interruption of later labor and
delivery. If the diagnosis of an extrauterine mass is not made
until later in the pregnancy, it is usually advisable to postpone
surgery until term, unless there is a high suspicion of cancer.
Cystic Teratoma
This case shows a fairly typical appearance of a very common
extrauterine mass (cystic teratoma [dermoid]) detected during
44
CASE 22
A
B
History: A woman presents with uncertain menstrual dates
in the late rst trimester for evaluation of embryonic age.
1. What should be included in the differential diagnosis of
Figure A? (Choose all that apply.)
A. Normal-appearing embryo with a crown-rump
conguration
B. Embryo with a mass
C. Conjoined (Siamese) twins
D. Dichorionic diamniotic twins
2. In the rst trimester, what are the ultrasound ndings to
determine that a twin gestation is dichorionic-diamniotic
(Di-Di)?
A. One sac with a membrane greater than 2 mm within
B. Two separate sacs and an interposed membrane greater
than 2 mm
C
C. Two separate sacs and no interposed membrane
D. One sac with no interposed membrane
3. What is a problem of conjoined twins at birth?
A. Cesarean delivery is required.
B. Immediate intubation is required.
C. Maternal hemorrhage is a signicant complication.
D. Preterm delivery is required.
4. What percentage of twins are fraternal?
A. 50%
B. 80%
C. 20%
D. 1%
45