Aarskog syndrome ; Aarskog-Scott
syndrome (AAS); faciogenital dysplasia.
A condition characterized by
slight to moderate short stature, hypertelorism,
small nose with anteverted nares, broad philtrum, orthodontic problems, brachydactyly,
prominent umbilicus, and shawl scrotum. A spectrum of behavioral disorders may be part
of the AAS phenotype. May be at increased risk for mental deficiency.
The condition is transmitted by mutations
in a gene called FGDY1 in band p11.21 on the X chromosome and follows
an X-linked recessive inheritance (sex-linked)
Online Mendelian Inheritance in Man®
Abdominal circumference (AC)
The distance around fetal abdomen.
The abdominal circumference is measured by sonogram from outer skin surface
to outer skin surface
The appropriate transverse plane for measurement of the fetal abdominal circumference (AC) should include the umbilical vein at the level where the umbilical vein enters the liver. The ossification centers of the spine should be aligned.
| UV =Umbilical
vein S= Spine
Abruptio placenta (Placental abruption)
Partial or complete separation of the placenta from the uterus before delivery. It
happens in 0.8-1.0% of all pregnancies and has a high recurrence
rate. Contractions are usually present. Bleeding is also present in
approximately 80% of patients.
Factors that have been associated with abruption include maternal hypertension, intrauterine growth restriction (IUGR), non-vertex presentation, polyhydramnios, advanced maternal age, maternal smoking, cocaine use, chorioamnionitis,
premature rupture of membranes, and blunt external maternal trauma
An acceleration is an abrupt increase in the fetal heart rate above baseline with onset to peak of
the acceleration less than 30 seconds and less than 2 minutes in duration.
Adequate accelerations are
32 weeks' gestation an
increase in heart rate greater than or equal to 10 beats per minute
above baseline for greater than or equal to
In a fetus greater than 32 weeks' gestation an increase
in heart rate greater than or equal to 15 beats per minute above
baseline for greater than or equal to 15 seconds.
Shortening of the hands or feet
Acute Cervical Insufficiency
Cervical dilation of at least 2 cm with membranes visible at 16 0/7 to 22 6/7
weeks' gestation as used by Owen J et al.
Owen J, et al. Multicenter randomized trial of cerclage for preterm birth
prevention in high-risk women with shortened midtrimester cervical length. Am J
Obstet Gynecol. 2009 Oct;201(4):375.e1-8.PMID:19788970
Agenesis of the corpus callosum (ACC)
A birth defect in which there is partial or complete absence of the corpus
callosum (the bundle of nerve fibers that connects the two hemispheres of the
ACC may occur as an isolated defect, but it is frequently associated with
other malformations, chromosomal abnormalities (trisomy 18 an trisomy 8), and genetic syndromes.
The outcome of the abnormality depends on the underlying cause and the
presence of other structural defects. Isolated ACC (in particular partial ACC) is associated with no or
mild neurologic impairment in a large proportion of cases. ACC occurring as part
of a syndrome may be associated with severe mental retardation and seizures. ACC does not cause
death in the majority of children.
Ultrasound findings include absence of the corpus callosum
and cavum septum pellucidum, 'teardrop' configuration of the lateral ventricles,
dilatation and upward displacement of the third ventricle (interhemispheric
"cyst") , and abnormal branching of the anterior cerebral artery.
Magnetic resonance imaging is sometimes useful in confirming the diagnosis.
Additional abnormalities commonly found in association with ACC include include Chiari
malformations, schizencephaly, encephaloceles, Dandy-Walker malformations, holoprosencephaly,
heart defects, and GI or genitourinary malformations.
The risk of recurrence
is ~ 1% for sporadic cases, 25% if ACC is associated with an autosomal
recessive cause, and 50% of males will be affected if inherited as an X-linked recessive disorder.
A protein produced by the fetal liver and yolk sac that can be detected in
the mother's blood. Alpha-fetoprotein levels rise gradually throughout most of
pregnancy and level off near term. High levels of alpha-fetoprotein are
associated with a more advanced pregnancy than expected, multiple pregnancy,
fetal death (including a vanished twin), an opening in the spine (spina bifida),
an opening in the head (anencephaly), or an opening in the abdominal wall
(gastroschisis). Low levels may be associated with Down syndrome, trisomy
18, and some cases of Turner syndrome.
A procedure in which a needle is inserted into the uterus and a sample of the
fluid surrounding the fetus is drawn out. The procedure may be done to evaluate
the fetal chromosomes, to determine fetal lung
maturity, or to obtain fluid to culture for possible infections. The procedure
may also be performed to remove an excessive amount of amniotic fluid.
Amniotic Fluid Index (AFI)
Amniotic fluid ‘sludge’
Kusanovic JP, et al. Clinical significance
of the presence of amniotic fluid 'sludge' in asymptomatic patients at high risk
for spontaneous preterm delivery. Ultrasound Obstet Gynecol. 2007
The sonographic finding of dense aggregates of particulate matter in the
amniotic fluid close to the internal cervical os. Amniotic Fluid (AF) ‘sludge’
has been associated with microbial invasion of the amniotic cavity (MIAC), and
histologic chorioamnionitis in patients with spontaneous preterm labor and
The membrane (amnion) that surrounds the fetus and the amniotic
A 'shelf' in the amniotic cavity seen during ultrasound examination. Amniotic sheets
represent chorion and amnion that has grown around uterine synechiae (
adhesions) . Incomplete amniotic sheets have a free edge. Complete
amniotic sheets have no free edge, and have been associated with increased risk
for intrauterine death.
Amniotic sheets may be mistaken for amniotic bands. However, amniotic bands more
often appear as multiple thin membranes, and are frequently attached to
the fetus. Circumvallate placenta is another cause of uterine band, sheet, or shelf.
Tan KB, Tan TY, Tan JV, Yan YL, Yeo GS. The amniotic sheet: a truly benign
condition?Ultrasound Obstet Gynecol. 2005 Nov;26(6):639-43.
Angle of insonation
A measure of deviation from
"straight on" to a reference plane measured in degrees. For example a Doppler
ultrasound beam aligned to the flow of blood in a vessel has a zero degree of
insonation to the flow. A Doppler
ultrasound beam aligned perpendicular to the flow of blood in the same vessel
has a 90 degree angle of insonation to the flow.
A birth defect resulting in the absence of a major portion of the skull and
brain. Anencephaly results when the upper portion of the neural tube fails to
close. The condition is not compatible with life, and infants usually die within
a few days after delivery. See picture
Angelman syndrome ("Happy Puppet Syndrome")
A disorder characterized by a large jaw and open-mouthed expression revealing
the tongue, severe speech impairment, motor and intellectual retardation,
ataxia, poor muscle tone, seizures, frequent laughing, smiling, and
excitability. The disorder is usually caused by abnormalities of chromosome 15.
A deletion of chromosome in the 15q11-q13 region accounts for up to 75% of
cases and has a less than 1% recurrence risk. Mutations in the UBE3A gene on
chromosome 15 accounts for 6 to 20% of cases and has a recurrence risk of less
than 1% unless the patient's mother carries the UBE3A mutation on her own
paternally inherited chromosome 15. In the latter case there is a 50% recurrence
risk. Angelman syndrome is less commonly caused by inheritance of two copies of
chromosome 15 from the father and no maternal copy of chromosome 15 (uniparental
disomy) , or mutations in the imprinting center of the UBE3A gene.
Absent or partially absent iris accompanied by macular and optic nerve
hypoplasia. Symptoms include poor vision sensitivity to light (photophobia),
and nystagmus. Frequently associated abnormalities include glaucoma
and cataracts. Mutation of the PAX 6 gene or deletion of a regulatory region controlling its expression, appears to be responsible for
aniridia occurring as an isolated ocular defect . The condition is
Aniridia may also occur as part of the Wilms tumor-aniridia-genital anomalies-retardation (WAGR) syndrome, with a deletion of 11p13 involving the PAX6 (aniridia) locus and the adjacent WT1 (Wilms
Steroids (either betamethasone or dexamethasone) given to help the fetal lungs and other organs mature more rapidly.
Antenatal steroids are given when preterm delivery is anticipated between 24 and 34 weeks' gestation with intact membranes, and
at 24 to 32 weeks' with ruptured membranes.
Proteins secreted by white blood cells (lymphocytes) that
bind to foreign molecules. Antibodies (immunoglobulins) are grouped into five classes or isotypes: IgG,
IgA, IgM, IgD, and IgE.
A molecules that stimulates antibody production is called an antigen (antibody generator).
Anti-c antibody (little c antibody)
A protein made by the immune system that binds to a molecule called the c antigen found on the surface of red blood cells. The c antigen is part of the
Rhesus blood group system which consists of several antigens (D
). The antibody hastens removal of the c antigen (and the foreign blood cells) from the body.
Anti-c antibody is capable of crossing the placenta and causing anemia in the fetus and
hemolytic disease of
the newborn. Pregnancies complicated by anti-c antibody are managed as for Rh-D sensitization .
Anti-D antibody (Rh sensitization, Rh disease)
A protein made by the immune system that binds to a molecule
called the D antigen found on the surface of red blood cells. The D antigen is
part of the Rhesus blood group system which consists of several antigens (D
). The antibody hastens removal of the D antigen (and the
foreign blood cells) from the body.
Anti-D antibody is capable of crossing the placenta and causing SEVERE anemia in the fetus and
hemolytic disease of
Anti-Duffy antibody (anti-Fya antibody)
A protein made by the immune system that binds to a molecule called the Fya
antigen found on the surface of red blood cells. The Fya antigen is part of the Duffy blood group system
which consists of the antigens Fya and
Fyb . The antibody hastens removal of the and Fya antigen (and the foreign blood cells) from the body.
Anti-Fya antibody is capable of crossing the placenta and causing SEVERE anemia in the fetus and
hemolytic disease of
the newborn. Anti-Fyb has not been reported to cause significant hemolytic disease of
A protein made by the immune system that binds to a molecule called the Kell antigen found on red blood cells. The Kell
antigen is part of the Kell blood group system which consists of several antigens ( Kell
or K1 , Kpa,
,Jsb ). The antibody hastens removal of the Kell antigen (and the foreign blood cells) from the body.
Anti-Kell antibody is capable of crossing the placenta and causing SEVERE anemia in the fetus and
hemolytic disease of the newborn.
SEE ALSO: Q & A ..a pregnant patient with
Anti-Kidd antibody (anti-Jka or anti-Jkb)
A protein made by the immune system that binds to a molecule called Kidd
antigen found on the surface of red blood cells.
The Kidd antigens Jka
are part of the Kidd blood group system.
Anti-Kidd antibody is capable of crossing the placenta and causing anemia in the fetus and hemolytic disease of
A protein made by the immune system that binds to molecules called the Lewis
a and Le b. Lewis antigens are not made by the red blood
cell, but are antigens present in body fluids and secretions that have been
adsorbed onto the surface of the red blood cell.
Lewis antigens are found in very low levels on the fetal red cells.
Most Lewis antibodies are of the IgM type and do not cross the placenta.
Lewis blood group antibodies are not known to cause
hemolytic disease of
A protein made by the immune system that bind to a molecule called the S antigen found on the surface of red blood cells.
The S antigen is part of the MNS blood group system which consists of several antigens (
Anti-S antibody is capable of crossing the placenta and causing anemia in the fetus and
hemolytic disease of
thickening of the wall of the uterus at the uterine fundus (top of the
uterus). The thickened area results from failure to completely dissolve the
uterine septum during development. The arcuate uterus is considered to be a mild form of
An arcuate uterus does not appear to have an unfavorable effect on
fourth ventricle is at the level of the foramen magnum. The cerebellar tonsils, parts of the cerebellum, pons, and medulla oblongata are displaced through the foramen magnum.
Typically accompanied by hydrocephalus
and myelomeningocele (open spina bifida).
A group of birth defects of the cerebellum (the part of the brain that
controls balance) and base of the skull characterized by downward displacement of the cerebellum and
related structures below the level of the foramen magnum (the large hole at the
base of the skull).
The three types of Arnold-Chiari malformation are:
- Type I:
The fourth ventricle (the fluid filled cavity between the cerebellum and pons of the
brainstem) remains in its normal position.
The lower most structures of the cerebellum (the cerebellar tonsils)
are displaced through the foramen magnum.
Many persons with a Type I malformation have no symptoms. However,
some persons may experience headache that is aggravated by
coughing and straining, weakness or loss of sensation of the upper arms
and hands, slurred speech,
trouble swallowing, dizziness, or trouble balancing.
- Type II:
Type III: Displacement of the fourth ventricle in addition to the the cerebellum, pons, and medulla oblongata through the foramen magnum.
Usually ccompanied by encephalocele or myelomeningocele .
Arrest of descent
No fetal descent after 1 hour during active labor.
Arrest of dilatation
No cervical change after 2 hours during active labor.
For management refer to "Dystocia and augmentation of labor. ACOG Practice
Bulletin No. 49. American College of Obstetricians and Gynecologists. Obstet
Gynecol 2003;102:1445–54.PMID: 14662243"
Stimulation the uterus to increase the frequency, duration , or strength of
contractions when spontaneous contractions have failed to cause dilation or thinning (effacement) of the cervix leading to the delivery of the infant.
1. World Health Organization. Managing Complications in Pregnancy and Childbirth .A guide for midwives and doctors. 2003. http://who.int/reproductive-health/impac/Procedures/Induction_P17_P25.html
ACOG Practice Bulletin No. 49.
2. American College of Obstetricians and Gynecologists. Dystocia and augmentation of labor.Obstet Gynecol 2003;102:1445–54.
A trait determined by a gene on any chromosome other than a sex chromosome
(X or Y) that requires only one gene for the trait to be expressed. The chance
of passing the trait to an offspring is at least 50% for each pregnancy.
A trait determined by a gene on any chromosome other than a sex chromosome
(X or Y) that requires two genes for the trait to be expressed. A person with
only one copy of the gene is said to be a carrier for the trait.
American College of Obstetricians and Gynecologists. Antepartum Fetal
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Cunningham FG. ed Williams Obstetrics, 22nd ed., New York:
Gabbe ed: Obstetrics - Normal and Problem Pregnancies, 4th ed New York, NY,
Churchill Livingstone; 2002
Jones, K.L. ed. Smith’s recognizable patterns of human malformation (5th ed.).
Philadelphia: W.B. Saunders.1997
Resnik R, ed., Maternal-Fetal Medicine, 5th ed., pp. 859–899. Philadelphia:
Stenchever MA, Droegemueller W, eds. Comprehensive Gynecology. 4th ed. St.
Louis: Mosby, 2001
Woodward PJ ed. Diagnostic Imaging Obstetrics, 1st ed., Manitoba: Amirsys, 2005
Ogueh O, et al., Obstetric implications of low-lying placentas diagnosed in the
Int J Gynaecol Obstet. 2003 Oct;83(1):11-7. PMID: 14511867