AND GYNECOLOGY

GA ≥ 2 weeks more advanced sonographically than by clinical estimate (AFP levels rise 15% per week during 16–18-week window)


C.  MULTIPLE GESTATIONS (14%)


D.  FETAL DEMISE (7%) / fetal distress / threatened abortion


E.  FETAL ANOMALIES (61%)


1.  Neural tube defects (51%):
anencephaly (30%), myelomeningocele (18%), encephalocele (3%), forebrain malformation
Prevalence:   1.6÷1,000 births in USA; 6÷1,000 births in Great Britain
◊  In 90% as 1st time event!
Risk of recurrence:   3% after one affected child; 6% after 2 affected children


2.  Ventral wall defects (21%):
gastroschisis, omphalocele (sensitivity of 50%)


3.  Proximal fetal gut obstruction:
esophageal / duodenal atresia
→ diminished AFP degradation in small bowel


4.  Cystic hygroma, teratoma: pharyngeal, sacral


5.  Amniotic band syndrome:
asymmetric cephalocele, gastropleuroschisis


6.  Renal abnormalities:
multicystic dysplastic kidney, renal agenesis, pelviectasis, congenital Finnish nephrosis → typically ≥ 10 MoM + negative amniotic fluid acetylcholinesterase


7.  Oligohydramnios


F.  PLACENTAL LESION
altering the placentomaternal barrier


1.  Chorioangioma


2.  Peri- and intraplacental hematoma
→ resulting in fetomaternal hemorrhage


3.  Placental lakes, infarct, intervillous thrombosis


G.  LOW BIRTH WEIGHT


H.  Normal pregnancy + MATERNAL DISORDER


1.  Hepatitis


2.  Hepatoma


I.  Fetal-maternal blood mixing:
collection of MS-AFP samples after amniocentesis


mnemonic:   GEM MINER CO


Gastroschisis


Esophageal atresia


Multiple gestations


Mole


Incorrect menstrual dates


Neural tube defects


Error: laboratory


Renal disease in fetus: autosomal recessive polycystic kidney disease, renal dysplasia, obstructive uropathy, congenital Finnish nephrosis


Chorioangioma


Omphalocele


ELEVATED MATERNAL SERUM AFP (MS-AFP)


=  defined as ≥ 2.5 MoM / equivalent to the 5th percentile: 4.5 MoM for multiple gestations


Power of detection at ≥ 2.5 MoM cutoff:


98% for gastroschisis


90% for anencephalic fetuses


75–80% for open spinal defects


70% for omphaloceles


Prevalence:   2–5% screen-positive rate (in 16% normal MS-AFP on retesting); 6–15% of fetuses have some type of major congenital defect; in 1.3÷1,000 tests fetal anomaly detected


◊  The higher the AFP elevation the higher the probability of fetal anomalies


◊  20–38% of women with unexplained high MS-AFP (ie, in the absence of fetal abnormality) suffer adverse pregnancy outcomes (premature birth, preeclampsia, 2–4 x IUGR, 10 x perinatal mortality, 10 x placental abruption)!


ELEVATED AMNIOTIC FLUID AFP (AF-AFP)


=  defined as ≥ 2 MoM (< 2 MoM has a 97% NPV)


Prevalence:   < 10% of women with elevated MS-AFP and “unrevealing” level I US exam


•  amniotic fluid also tested for karyotype + acetylcholinesterase (= neurotransmitter enzyme present when neural tissue is exposed)


◊  66% of fetuses with ↑ maternal AF-AFP are normal!


◊  A targeted level II ultrasound exam will show fetal anomalies in 33%!


Low Alpha-fetoprotein


=  MS-AFP ≤ 0.5 / AF-AFP ≤ 0.72 MoM


Prevalence:   3%


1.   Autosomal trisomy syndromes: trisomy 21, 18, 13


◊  20% of trisomy 21 fetuses are found in women with low MS-AFP after adjustment for age!


2.   Absence of fetal tissues: eg, hydatidiform mole


3.   Fetal demise


4.   Misdated pregnancy


5.   Normal pregnancy


6.   Patient not pregnant


Use of Karyotyping


Frequency:   11–35% of fetuses with sonographically identified abnormalities have chromosomal abnormalities


A.  FETAL ANOMALIES


1.   CNS anomalies: holoprosencephaly (43–59%), Dandy-Walker malformation (29–50%), cerebellar hypoplasia, agenesis of corpus callosum, myelomeningocele (33–50%)


2.   Cystic hygroma (72%): Turner syndrome


3.   Omphalocele (30–40%)


4.   Cardiac malformations


5.   Nonimmune hydrops


6.   Duodenal atresia


7.   Severe early-onset IUGR: trisomy 18, 13, triploidy


8.   Congenital diaphragmatic hernia


9.   Bone-echodense bowel (20%): trisomy 21


B.  MATERNAL RISK FACTORS


1.   Advanced age


2.   Low serum alpha-fetoprotein


3.   Abnormal triple screen of maternal serum


4.   History of previous chromosomally abnormal pregnancy (1% risk of recurrence)



C.  PLANNED INTENSE INTRAUTERINE MANAGEMENT


Fetal anomalies not associated with chromosomal anomalies:


1.   Gastroschisis


2.   Unilateral renal anomaly


3.   Intestinal obstruction distal to duodenal bulb


4.   Off-midline unilateral cleft lip


5.   Fetal teratoma: sacrococcygeal / anterior cervical


6.   Isolated single umbilical artery


AMNIOTIC FLUID VOLUME


Production:


(a)  1st trimester: dialysate of maternal + fetal serum across the noncornified fetal skin


(b)  2nd + 3rd trimester: fetal urine (600–800 cm3/d near term), fetal lungs (600–800 cm3/d near term), amniotic membrane


Absorption:


fetal swallowing + GI absorption, fetal lung absorption, clearance by placenta


Assessment of amniotic fluid volume by:


(1)  Subjective assessment (“Gestalt” method):


quick + efficient, accounts for GA-related variations in fluid volume, considered the most accurate if performed by experienced operator, operator + interpreter must be identical, no documentation, variations on serial scans difficult to appreciate


(2)  Depth of largest vertical pocket:


simple + quick (used in BPP), pockets > 2 cm may be found in crevices between fetal parts with moderately severe oligohydramnios, does not account for GA-related variations


(3)  Four-quadrant Amniotic Fluid Index (AFI):


fairly quick, probably correlates better with fluid volume than any single measurement, may not accurately reflect overall fluid volume, may be affected by fetal movement during measurements


(4)  Planimetric measurement of total intrauterine volume


(5)  Dye / para-aminohippurate dilution technique:


800 cm3 at 34 weeks, 500 cm3 > 34 weeks


Polyhydramnios


=  amniotic fluid volume > 1,500–2,000 cm3 at term


Prevalence:   1.1–2–3.5%


√  fetus does not fill the AP diameter of uterus


√  single largest pocket devoid of fetal parts / cord > 8 cm in vertical direction


√  AFI ≥ 20–24 cm


Prognosis:  64% perinatal mortality with severe polyhydramnios


Etiology:


A.  IDIOPATHIC (35%)


Associated with:   macrosomia in 19–37%


Suggested cause:


(1)  Increased renal vascular flow


(2)  Bulk flow of water across surface of fetus + umbilical cord + placenta + membranes


B.  MATERNAL CAUSES (36%)


1.   Diabetes (25%)


2.   Isoimmunization: Rh incompatibility (11%)]


3.   Placental tumors: chorioangioma


C.  FETAL ANOMALIES (20%)


(a)  gastrointestinal anomalies (6–16%):


impairment of fetal swallowing (esophageal atresia in 3%); high intestinal atresias / obstruction of duodenum / proximal small bowel (1.2–1.8%), omphalocele, meconium peritonitis


(b)  nonimmune hydrops (16%)


(c)  neural tube defects (9–16%):


anencephaly, hydranencephaly, holoprosencephaly, myelomeningocele, ventriculomegaly, agenesis of corpus callosum, encephalocele, microcephaly


(d)  chest anomalies (12%):


diaphragmatic hernia, cystic adenomatoid malformation, tracheal atresia, mediastinal teratoma, primary pulmonary hypoplasia, extralobar sequestration, congenital chylothorax


(e)  skeletal dysplasias (11%):


dwarfism (thanatophoric dysplasia, achondroplasia), kyphoscoliosis, platyspondyly


(f)  chromosomal abnormalities (9%):


trisomy 21, 18, 13


(g)  cardiac anomalies (5%):


VSD, truncus arteriosus, ectopia cordis, septal rhabdomyoma, arrhythmia


(h)  genitourinary malformations:


unilateral UPJ obstruction, unilateral multicystic dysplastic kidney, mesoblastic nephroma


Cause:   ? hormonally mediated polyuria


(i)  miscellaneous (8%):


cystic hygroma, facial tumors, cleft lip / palate, teratoma, amniotic band syndrome, congenital pancreatic cyst


◊  In polyhydramnios efforts to detect fetal anomalies should be directed at SGA fetuses!


mnemonic:   TARDI


Twins


Anomalies, fetal


Rh incompatibility


Diabetes


Idiopathic


Oligohydramnios


=  amniotic fluid volume < 500 cm3 at term


√  single largest pocket devoid of fetal parts / cord ≤ 1–2 cm in vertical direction


√  AFI ≤ 5–7 cm


Etiology:


mnemonic:   DRIPP


Demise of fetus / Drugs (Motrin® therapy for tocolysis of preterm labor)


Renal anomalies, bilateral (= inadequate urine production): renal agenesis / dysgenesis, infantile polycystic kidney disease, prune belly syndrome, posterior urethral valves, urethral atresia, cloacal anomalies


◊  20-fold increase in incidence of fetal anomalies with oligohydramnios!


N.B.:   bilateral renal obstruction, if combined with intestinal obstruction, may be associated with polyhydramnios


IUGR: ← reduced renal perfusion


Premature rupture of membranes (most common)


Postmaturity


Cx:     pulmonary hypoplasia, cord compression


Prognosis:  77–100% perinatal mortality with 2nd trimester oligohydramnios


ABNORMAL FIRST TRIMESTER FINDINGS


Time of onset:   prior to 8–10 weeks


First Trimester Bleeding


=  VAGINAL BLEEDING IN FIRST TRIMESTER


Frequency:   15–25% of all pregnancies, of which 50% terminate in abortion


A.  INTRAUTERINE CONCEPTUS IDENTIFIED


1.   Threatened abortion


2.   Embryonic demise


3.   Blighted ovum


4.   Gestational trophoblastic disease


5.   Implantation bleed: 3–4 weeks after last menstrual period


6.   Subchorionic hemorrhage


7.   Low-lying placenta previa


8.   Twin loss


B.  NORMAL ENDOMETRIAL CAVITY


(a)  with β-hCG level > 1,800 mlU/mL


1.   Recent spontaneous abortion


2.   Ectopic pregnancy


(b)  with β-hCG level < 1,800 mIU/mL


1.   Very early IUP


2.   Ectopic pregnancy


C.  SAC VULNERABILITY


1.   Leiomyoma


2.   Intrauterine contraceptive device


Hemoperitoneum during Pregnancy


=  hemorrhage in cul-de-sac (= rectouterine pouch)


1.   Hemorrhagic corpus luteum cyst


2.   Placenta accreta


3.   Spontaneous abortion


4.   Ectopic pregnancy


5.   HELLP syndrome


6.   Uterine rupture





Abnormal Sonographic Findings in 1st Trimester


1.   Embryonic demise = abortion (clinical term)


2.   Nondevelopment = blighted ovum


3.   Maldevelopment = hydatidiform mole


Empty Gestational Sac


1.   Normal early IUP between 5 and 7 weeks MA


2.   Blighted ovum


DDx:  Pseudosac of ectopic pregnancy


Gestational Sac in Low Position


1.   Abortion in progress


√  no placental blood flow


2.   Cervical ectopic pregnancy


3.   Fundal fibroid compressing sac downward


Pregnancy of Unknown Location


=  normal pelvic US = transient state of early pregnancy during which no definite IUP is visualized at US with normal adnexa


=  positive β-hCG without IUP


mnemonic:   HERE


HCG-producing tumor (rare)


Ectopic pregnancy: occult


Recent completed spontaneous abortion


Early intrauterine pregnancy



In a hemodynamically stable patient with a pregnancy of unknown location, it is less harmful to wait, follow the β-hCG levels, and repeat the US examination than to presumptively treat an ectopic pregnancy.


hCG-producing Tumor


1.   Gestational trophoblastic disease: hydatidiform mole, gestational choriocarcinoma


2.   Ovarian malignant germ cell tumor


3.   Nontesticular teratoma


4.   Nontrophoblastic tumor: hepatoma, neuroendocrine tumor, breast cancer, pancreatic cancer, cervical cancer, gastric cancer, malignant phyllodes tumor


5.   Spurious laboratory finding


Thickened Central Cavity Complex


1.   Intrauterine blood


2.   Retained products of conception following an incomplete spontaneous abortion


3.   Early intrauterine not yet visible pregnancy


4.   Decidual reaction ← ectopic pregnancy


Uterus Large for Dates


1.   Multiple gestation pregnancy


2.   Inaccurate menstrual history


3.   Fibroids


4.   Polyhydramnios


5.   Hydatidiform mole


6.   Fetal macrosomia


Intrauterine Membrane in Pregnancy


A.  MEMBRANE OF MATERNAL ORIGIN


1.   Uterine septum


=  incomplete resorption of sagittal septum between the fused two müllerian ducts


2.   Amniotic sheet / shelf


=  folding of amniochorionic membrane around uterine synechia


√  synechia often thins during uterine stretching + disappears as pregnancy progresses


3.   Wisps of umbilical cord


B.  MEMBRANE OF FETAL ORIGIN


1.   Intertwin membrane


=  apposing membrane of multiple pregnancy / residual sac of blighted twin pregnancy


2.   Amniotic band


=  rent within amnion


3.   Chorioamnionic separation


=  incomplete fusion / hemorrhagic separation of amnion (= inner membrane) and chorion (= outer membrane)


4.   Subchorionic hemorrhage = chorioamnionic elevation


=  separation of chorionic membrane from decidua


•  implantation bleed of early pregnancy


C.  FIBRIN STRAND


Cause:   hemorrhage during transplacental amniocentesis


mnemonic:   STABS


Separation (chorioamnionic)


Twins (intertwin membrane)


Abruption


Bands (amniotic band syndrome)


Synechia


Dilated Cervix


1.   Inevitable abortion


2.   Premature labor


=  spontaneous onset of palpable, regularly occurring uterine contractions between 20 and 37 weeks MA


3.   Incompetent cervix


PLACENTA


Abnormal Placental Size


◊  Placental mass tends to reflect fetal mass!


A.  ENLARGEMENT OF PLACENTA = Placentomegaly


=  > 5 cm thick in sections obtained at right angles to long axis of placenta


(a)  maternal disease


1.   Maternal diabetes ← villous edema


2.   Chronic intrauterine infections: eg, syphilis


3.   Maternal anemia: normal histology


4.   Alpha-thalassemia


(b)  fetal disease


1.   Hemolytic disease of the newborn ← villous edema + hyperplasia ← immunologic incompatibility including Rh sensitization


2.   Umbilical vein obstruction


3.   Fetal high-output failure:


large chorioangioma, arteriovenous fistula


4.   Fetal malformation:


Beckwith-Wiedemann syndrome, sacrococcygeal teratoma, chromosomal abnormality, fetal hydrops


5.   Twin-twin transfusion syndrome


(c)  fetomaternal hemorrhage


(d)  placental abnormalities


1.   Molar pregnancy


2.   Chorioangioma


3.   Intraplacental hemorrhage


mnemonic:   HAD IT


Hydrops


Abruption


Diabetes mellitus


Infection


Triploidy


B.  DECREASE IN PLACENTAL SIZE


1.   Preeclampsia: associated with placental infarcts in 33–60%


2.   IUGR


3.   Chromosomal abnormality


4.   Intrauterine infection


Vascular Spaces of the Placenta


1.   “Placental cysts


=  large fetal veins located between amnion + chorion anastomosing with umbilical vein


√  sluggish blood flow (detectable by real-time observation)


2.   Basal veins


=  decidual + uterine veins


√  lacy appearing network of veins underneath placenta


DDx:   placental abruption


3.   Intraplacental venous lakes


√  intraplacental sonolucent spaces


√  whirlpool motion pattern of flowing blood


Placental Causes of Antepartum Hemorrhage


=  vaginal bleeding between 20 wks GA and delivery


1.   Placenta previa


2.   Placental abruption = placental hematoma


›  on fetal side


(a)  Subchorionic = preplacental hematoma


›  on maternal side


(b)  Retroplacental hematoma


(c)  Intraplacental hematoma


Macroscopic Lesion of the Placenta


1.   Intervillous thrombosis (36%)


=  intraplacental areas of hemorrhage


Etiology:   breaks in villous capillaries with bleeding from fetal vessels


√  irregular sonolucent intraplacental lesions (mm to cm range)


√  blood flow may be observed within lesion


Significance:   fetal-maternal hemorrhage (Rh sensitization, elevated AFP levels)


2.   Perivillous fibrin deposition (22%)


=  nonlaminated collection of fibrin deposition


Etiology:   thrombosis of intervillous space


Significance:   none


3.   Septal cyst (19%)


Etiology:   obstruction of septal venous drainage by edematous villi


√  5–10-mm cyst within septum


Significance:   none


4.   Placental infarct (25%)


=  coagulation necrosis of villi


Etiology:   disorder of maternal vessels, retroplacental hemorrhage


√  not visualized unless hemorrhagic


√  well-circumscribed mass with hyperechoic / mixed echo pattern


Significance:   dependent on extent + associated maternal condition


5.   Subchorionic fibrin deposition (20%)


=  laminated collection of fibrin deposition


Etiology:   thrombosis of maternal blood in subchorionic space


√  subchorionic sonolucent area


Significance:   none


6.   Massive subchorial thrombus


=  BREUS MOLE = PREPLACENTAL HEMORRHAGE


Placental Tumor


A.  TROPHOBLASTIC


1.   Complete hydatidiform mole


2.   Partial hydatidiform mole


3.   Invasive mole


4.   Choriocarcinoma


B.  NONTROPHOBLASTIC


1.   Chorioangioma (in up to 1% of placentas)


2.   Teratoma (rare)


3.   Metastatic lesion (rare): melanoma, breast carcinoma, bronchial carcinoma


Unbalanced Intertwin Transfusion


=  unbalanced intertwin transfusion through vascular anastomoses between 2 circulations of monochorionic twins


A.  ACUTE   = Twin-embolization syndrome


B.  CHRONIC   = Twin-twin transfusion syndrome


C.  REVERSE   = Acardiac twinning


UMBILICAL CORD


Abnormal Umbilical Cord Insertion


1.   Marginal cord insertion


=  cord insertion < 1–2 cm from placental edge


Frequency:   5–7% of pregnancies


2.   Battledore placenta


[battledore = flat wooden paddle in ancient form of badminton]


=  cord insertion on edge of placenta = extreme marginal


•  no clinical significance


3.   Velamentous cord insertion


4.   Vasa previa


Distortion Abnormality of Umbilical Cord


1.   Cord torsion


=  excessive twisting of cord as rare form of cord constriction


Timing:   any time during pregnancy; more common during 2nd and 3rd trimester


√  evaluation of pitch value of cord coiling


√  abnormal S/D flow velocity ratio of umbilical artery


Cx:   critically reduced fetal blood flow and fetal hypoxia, oligohydramnios, IUGR, and fetal death


Dx:   difficult to diagnose prenatally; mostly detected during postnatal examination


2.   Cord entanglement


Cause:   nearby umbilical cord insertions on single placenta in monoamniotic twin pregnancy


√  branching pattern at level of entanglement


√  end systolic notch on umbilical artery waveform ← vascular compression / narrowing


Cx:   vascular compromise in one / both fetuses → fetal demise


3.   Noncoiled “straight” cord


counterclockwise÷clockwise umbilical cords = 7÷1


right-handed÷left-handed persons = 7÷1


Prevalence:   3.7–5%


√  absent vascular coiling for entire length of visible cord


At risk for:   intrauterine death (8%), stillbirth, fetal anomalies (24%), prematurity, intrapartum heart rate decelerations, fetal distress, meconium staining


4.   Body cord


=  loop around fetal body / any fetal body part


5.   Nuchal cord


Umbilical Cord Lesion


A.  DEVELOPMENTAL CORD LESION


1.   Umbilical hernia


=  protrusion from anterior abdominal wall with normal insertion of umbilical vessels


Predisposed:


Blacks, low-birth-weight infants, trisomy 21, congenital hypothyroidism, Beckwith-Wiedemann syndrome, mucopolysaccharidoses


Prognosis:   spontaneous closure in first 3 years of life


2.   Umbilical cord cyst


B.  ACQUIRED CORD LESION


1.    False knot


(a)  exaggerated looping of cord vessels → focal dilatation of cord


(b)  focal accumulation of Wharton jelly


(c)  varix of umbilical vessel


•  clinically insignificant


√  knoblike protrusion / bulge of cord


2.   True knot


Prevalence:   1% of pregnancies


Cause:   excessive fetal movements


Predisposed:   long cord, polyhydramnios, small fetus, monoamniotic twins


√  “hanging noose” sign = segment of umbilical cord closely surrounded by another loop of cord


√  local distension / thrombosis of umbilical vein near cord knot resembling an umbilical cyst


√  tortuosity of cord at level of knot


Cx:   vascular occlusion → fetal asphyxia → fetal demise


OB management:   expectant (mostly loose knot with marginal impact on fetal well-being)


3.   Umbilical cord hematoma


=  rupture of the wall of the umbilical vein ← mechanical trauma (cordocentesis, torsion, loops, knots, traction) / congenital weakness of vessel wall


Prevalence:   0.02% of pregnancies


Location:   near fetal insertion of umbilical cord (most common)


√  hyper- / hypoechoic mass 1–2 cm in size, multiple (in 18%)


Cx:   rupture into amniotic cavity → exsanguination


Prognosis:   52% overall perinatal fetal mortality


4.   Neoplasm


(a)  Angiomyxoma / hemangioma of cord


Prevalence:   22 cases in literature


Histo:   multiple vascular channels lined by benign endothelium surrounded by edema + myxomatous degeneration of Wharton jelly


Associated with:   single umbilical artery


•  increased maternal serum α-fetoprotein level


Location:   more frequently near placental insertion of umbilical cord


√  hyperechoic / multicystic mass within cord


√  may be associated with pseudocyst (= localized collection of edema)


√  blood flow on Doppler


Cx:   premature delivery, stillbirth, hydramnios, nonimmune hydrops, massive hemorrhage ← rupture


(b)  Other tumors: myxosarcoma, dermoid, teratoma


Umbilical Cord Cyst


◊  Umbilical cord cysts persisting into 2nd + 3rd trimester are frequently accompanied by fetal anomalies: angiomyxoma of cord, hernia, intestinal obstruction, urinary tract obstruction, urachal anomalies, imperforate anus, TE fistula, omphalocele, cardiac defect, trisomy 18


Location:   toward fetal insertion of cord


A.  UMBILICAL CORD PSEUDOCYST (common)


=  Mucoid degeneration of umbilical cord


=  Wharton jelly cyst


Histo:  localized edema + liquefaction of Wharton jelly without epithelial lining


Commonly associated with:   omphalocele


√  focal thickening of Wharton jelly


Prognosis:  usually resolved by 12 weeks MA


B.  TRUE UMBILICAL CORD CYST (rare)


Prevalence:  3.4% of 1st trimester pregnancies; 20% persist into 2nd trimester


Histo:   lined by single layer of flattened epithelium


Rarely associated with:   fetal structural anomaly, aneuploidy


Size:  4–60 mm in diameter


1.   Omphalomesenteric duct cyst


Site:   eccentric in cord


2.   Allantoic cyst


=  remnant of umbilical vesicle / allantois; usually degenerates by 6 weeks


Site:   in center of cord


3.   Amniotic inclusion cyst


=  amniotic epithelium trapped within umbilical cord


Vascular Abnormalities of Umbilical Cord


1.   Single umbilical artery


2.   Persistent Right Umbilical Vein (PRUV)


=  regression of left umbilical vein → abnormal course of blood flow in fetal liver


Frequency:   0.1–0.3%


Cause:   altered development of umbilical cord during 4th –7th week GA


May be associated with:   situs inversus, heterotaxy, anomalies of GU / GI tract, heart, skeletal development


Path of blood flow:


(a)  intrahepatic PRUV = isolated right umbilical vein joins fetal portal system at sinus venosus + gives rise to ductus venosus


(b)  extrahepatic PRUV = right umbilical vein bypasses liver and drains into RA / IVC / right iliac vein + absent ductus venosus


√  fetal portal vein curves toward (rather than parallel to) stomach


√  fetal gallbladder between umbilical vein and stomach + medial (rather than lateral) to umbilical vein


√  umbilical vein connects to right (rather than left) portal vein


3.   Umbilical vein / Cord varix


Frequency:   < 4% of all umbilical cord abnormalities


May be associated with:   aneuploidy (6%), other fetal anomalies (28%)


Site:   intraamniotic / intraabdominal, intrahepatic / extrahepatic


Normal size of umbilical vein:   3 mm at 15 weeks GA, 8 mm at term


√  fusiform dilatation of umbilical vein > 9 mm


√  transverse diameter of extrahepatic umbilical vein > 1.5 x greater than intrahepatic component


√  vein diameter > 2 SD above mean diameter for GA


√  fetal hydrops, anemia, IUGR










Cx:

(1)  Thrombosis with subsequent fetal death

 

(2)  Partial thrombosis with IUGR


◊  Serial US examinations are recommended from diagnosis to delivery!


Prognosis:   usually no clinical significance


4.   Umbilical artery aneurysm Often associated with single umbilical artery, aneuploidy, fetal structural abnormalities


SMALL-FOR-GESTATIONAL AGE FETUS (SGA)


=  generic clinical term describing a group of perinates at / below 10th percentile for gestational age without reference to etiology


1.   Fetus of appropriate growth (misdiagnosed as small)


2.   Small normal fetus = constitutionally small fetus (80–85%)


◊  No indication for surveillance / intervention!


3.   Small abnormal fetus = primary growth failure associated with karyotype anomaly / fetal infection (5–10%)


◊  Active intervention is of no benefit!


4.   Dysmature fetus = IUGR = growth failure as a result of uteroplacental insufficiency (10–15%)


◊  Intensive management is likely of benefit!


FETAL OVERGROWTH DISORDER


1.   Beckwith-Wiedemann syndrome


2.   Simpson-Golabi-Behmenl syndrome


3.   Perlman syndrome


FETAL SKELETAL DYSPLASIA


=  DWARFISM


=  heterogeneous group of bone growth disorders resulting in abnormal shape + size of the skeleton


◊  More than 200 skeletal dysplasias are known, but only a few are frequent:


›  thanatophoric dysplasia


›  osteogenesis imperfecta type II


›  achondrogenesis


›  heterozygous achondroplasia


Birth prevalence:


2.3÷10,000–7.6÷10,000 births for all skeletal dysplasias; 1.5÷10,000 births for lethal skeletal dysplasias


Prognosis:   51% mortality ← hypoplastic lungs: 23% stillbirths, 32% death in 1st week of life


Terminology:




















































Amelia = absence of limb
Hemimelia = absence of distal parts
Micromelia = shortening involves entire limb (eg, humerus, radius + ulna, hand)
Rhizomelia = shortening involves proximal segment (ie, humerus / femur)
    [rhiza, Greek = root of extremity = shoulder / hip]
Mesomelia = shortening involves intermediate segment (ie, radius + ulna / tibia + fibula)
    [mesos, Greek= middle]
Acromelia = shortening involves distal segment (eg, hand)
Meromelia = partial absence of a limb
Phocomelia = proximal reduction with distal parts attached to trunk
Preaxial polydactyly = extra digit on radial / tibial side
Postaxial polydactyly = extra digit on ulnar / fibular side

Classification:


(1)  OSTEOCHONDRODYSPLASIA


=  abnormalities of cartilage / bone growth and development


(a)  identifiable at birth:


›  usually lethal: achondrogenesis, fibrochondrogenesis, thanatophoric dysplasia, short rib syndrome


›  usually nonlethal: chondrodysplasia punctata, camptomelic dysplasia, achondroplasia, diastrophic dysplasia, chondroectodermal dysplasia, Jeune syndrome, spondyloepiphyseal dysplasia congenita, mesomelic dysplasia, cleidocranial dysplasia, otopalatodigital syndrome


(b)  identifiable in later life: hypochondroplasia, dyschondrosteosis, spondylometaphyseal dysplasia, acromicric dysplasia


(c)  abnormal bone density: osteopetrosis, pyknodysostosis, Melnick-Needles syndrome


(2)  DYSOSTOSIS


=  malformation of individual bones singly / in combination


(a)  with cranial + facial involvement: craniosynostosis, craniofacial dysostosis (Crouzon), acrocephalosyndactyly, acrocephalopolysyndactyly, branchial arch syndromes (Treacher-Collins, Franceschetti, acrofacial dysostosis, oculoauriculo-vertebral dysostosis, hemifacial microsomia, oculomandibulofacial syndrome)


(b)  with predominant axial involvement: vertebral segmentation defects (Klippel-Feil), Sprengel anomaly, spondylocostal dysostosis, oculovertebral syndrome


(c)  with predominant involvement of extremities: acheiria (= absence of hands), apodia (= absence of feet), polydactyly, syndactyly, camptodactyly, Rubinstein-Taybi syndrome, pancytopenia-dysmelia syndrome (Fanconi), Blackfan-Diamond anemia with thumb anomaly, thrombocytopenia-radial aplasia syndrome, cardiomelic syndromes (Holt-Oram), focal femoral deficiency, multiple synostoses


(3)  IDIOPATHIC OSTEOLYSIS


=  disorders with multifocal resorption of bone


(4)  CHROMOSOMAL ABERRATION


(5)  PRIMARY METABOLIC DISORDER


(a)  calcium / phosphorus: hypophosphatasia


(b)  complex carbohydrates: mucopolysaccharidosis


Assessment of:


1.   Long bones for absence, hypoplasia, malformation, curvature, degree of mineralization, fractures, premature ossification centers


√  shortening of long bones (common characteristic)


◊  Femur length > 5 mm below 2 standard deviations suggests skeletal dysplasia!


√  FL÷foot length < 0.9 = suggests skeletal dysplasia


√  limb shortening of 40–60% of the mean in thanatophoric dysplasia + OI type II


√  limb shortening of > 30% of the mean in achondrogenesis


2.   Thorax for shape, abnormal rib size, absence / hypoplasia of clavicles, presence of scapula


√  Chest Circumference < 5th percentile (= lung hypoplasia)


√  Chest Circumference÷AC < 5th percentile


√  heart area÷chest area < 5th percentile


√  FL÷AC < 0.16 = suggests lung hypoplasia


2.   Hand & foot for clinodactyly, syndactyly, pre- or postaxial polydactyly


√  “hitchhiker’s thumb”, radial ray anomaly, absence of thumb


√  “rocker-bottom” foot, clubbed foot


4.   Skull for size, shape (brachycephaly, scaphocephaly, craniosynostosis, frontal bossing, cloverleaf skull), degree of mineralization


√  HC and BPD


√  binocular and interocular diameter


√  micrognathia, short upper lip, abnormally shaped ears


4.   Spine for relative total length, scoliosis, mineralization of vertebral bodies, integrity of neural arches, vertebral height, absence of segments


5.   Pelvis for shape


Associated with:   polyhydramnios


DDx features:   mineralization, bowing, fractures, number of digits, fetal movement, thoracic measurement, associated anomalies, age of onset


DDx:   constitutionally short limbs, severe IUGR


Micromelic Dwarfism


=  disproportionate shortening of entire leg


A.  Mild micromelic dwarfism


1.   Jeune syndrome


2.   Chondroectodermal dysplasia


3.   Diastrophic dwarfism


B.  Mild bowed micromelic dwarfism


1.   Camptomelic dysplasia


2.   Osteogenesis imperfecta, type III


C.  Severe micromelic dwarfism


1.   Thanatophoric dysplasia


2.   Osteogenesis imperfecta, type II


3.   Homozygous achondroplasia


4.   Hypophosphatasia


5.   Short-rib polydactyly syndrome


6.   Fibrochondrogenesis


Acromelic Dwarfism


Asphyxiating thoracic dysplasia


Rhizomelic Dwarfism


mnemonic:   MA CAT


Metatrophic dwarfism


Achondrogenesis (most severe shortening)


Chondrodysplasia punctata: autosomal recessive


Achondroplasia, heterozygous


Thanatophoric dysplasia


Osteochondrodysplasia


A.  Failure of


(a)  articular cartilage: spondyloepiphyseal dysplasia


(b)  ossification center: multiple epiphyseal dysplasia


(c)  proliferating cartilage: achondroplasia


(d)  spongiosa formation: hypophosphatasia


(e)  spongiosa absorption: osteopetrosis


(f)  periosteal bone: osteogenesis imperfecta


(g)  endosteal bone: idiopathic osteoporosis


B.  Excess of


(a)  articular cartilage: dysplasia epiphysealis hemimelica


(b)  hypertrophic cartilage: enchondromatosis


(c)  spongiosa: multiple exostosis


(d)  periosteal bone: progressive diaphyseal dysplasia


(e)  endosteal bone: hyperphosphatemia


Lethal Bone Dysplasia


in order of frequency:


1.   Thanatophoric dysplasia


2.   Osteogenesis imperfecta type II


3.   Achondrogenesis type I + II


4.   Jeune syndrome (may be nonlethal)


5.   Hypophosphatasia, congenital lethal form


6.   Chondroectodermal dysplasia (usually nonlethal)


7.   Chondrodysplasia punctata, rhizomelic type


8.   Camptomelic dysplasia


9.   Short-rib polydactyly syndrome


10.   Homozygous achondroplasia


◊  Lethal short-limbed dysplasias typically are manifest on sonograms < 24 weeks MA!


Nonlethal Dwarfism


1.   Achondroplasia (heterozygous)


2.   Asphyxiating thoracic dysplasia


3.   Chondroectodermal dysplasia


4.   Chondrodysplasia punctata


5.   Spondyloepiphyseal dysplasia (congenital)


6.   Diastrophic dysplasia


7.   Metatrophic dwarfism


8.   Hypochondroplasia


Late-onset Dwarfism


1.   Spondyloepiphyseal dysplasia tarda


2.   Multiple epiphyseal dysplasia


3.   Pseudoachondroplasia


4.   Metaphyseal chondrodysplasia


5.   Dyschondrosteosis


6.   Cleidocranial dysostosis


7.   Progressive diaphyseal dysplasia


Hypomineralization in Fetus


A.  DIFFUSE


1.   Osteogenesis imperfecta


2.   Hypophosphatasia


B.  SPINE


1.   Achondrogenesis


Large Head in Fetus


1.   Achondroplasia


2.   Thanatophoric dysplasia


Narrow Hypoplastic Chest in Fetus


1.   Short-rib polydactyly syndrome


2.   Asphyxiating thoracic dysplasia


3.   Chondroectodermal dysplasia


4.   Camptomelic dysplasia


5.   Thanatophoric dysplasia


6.   Homozygous achondroplasia


7.   Achondrogenesis


8.   Hypophosphatasia


9.   Osteogenesis imperfecta


Platyspondyly


1.   Thanatophoric dysplasia


2.   Osteogenesis imperfecta type II


3.   Achondroplasia


4.   Morquio syndrome


Bowed Long Bones in Fetus


1.   Camptomelic syndrome


2.   Osteogenesis imperfecta


3.   Thanatophoric dysplasia


4.   Hypophosphatasia


Bone Fractures in Fetus


1.   Osteogenesis imperfecta


2.   Hypophosphatasia


3.   Achondrogenesis


Acrocephalosyndactyly


=  syndrome characterized by


(1)  increased height of skull vault ← generalized craniosynostosis (= acrocephaly, oxycephaly)


(2)  syndactyly of fingers / toes


Type 1:   Apert syndrome


Type 2:   Crouzon syndrome


Type 3:   Saethre-Chotzen syndrome


Type 4:   Wardenburg type


Type 5:   Pfeiffer syndrome


Acrocephalopolysyndactyly


Type 1:   Noack syndrome


Type 2:   Carpenter syndrome


Type 3:   Sakati-Nyhan-Tisdale syndrome


Type 4:   Goodman syndrome


Type 5:   Pfeiffer syndrome


LIMB REDUCTION ANOMALIES


Prevalence:   0.49 ÷10,000 births


Isolated Extremity Amputation


1.   Amniotic band syndrome


2.   Exposure to teratogen


3.   Vascular accident


Aplasia / Hypoplasia of Radius


mnemonic:   The Furry Cat Hit My Dog


Thrombocytopenia–absent radius syndrome


Fanconi anemia


Cornelia de Lange syndrome


Holt-Oram syndrome


Myositis ossificans progressiva (thumb only)


Diastrophic dwarfism (“hitchhiker’s thumb”)


Pubic Bone Maldevelopment


mnemonic:   CHIEF


Cleidocranial dysostosis


Hypospadia, epispadia


Idiopathic


Exstrophy of bladder


F for syringomyelia


Fetal Hand Anomalies


Best time for assessment:


late 1st to middle 2nd trimester ← ossification of metacarpals beginning at 12 weeks EGA + frequent fetal movement


◊  Complete fetal work-up needed for associated anomalies!


Normal findings:


›  unossified hypoechogenic carpus


›  5 hyperechoic + cylindric metacarpal bones


›  5 independent digits of different lengths with 3 ossified phalanges (2 for thumb)


›  normal radius, ulna, humerus


›  flexion (fist) + extension (unclenched hand)


Classification:


(a)  abnormal alignment: clenched hand, camptodactyly, clinodactyly, akinesia deformation sequence, clubhand, phocomelia


(b)  thumb anomalies: macrodactyly, trident hand


(c)  abnormal number: polydactyly, syndactyly, ectrodactyly


Camptodactyly


=  flexion contracture of PIP joint of any finger


Cause:   karyotype anomaly (trisomy 18, 13, 15) or contracture syndrome; may be isolated


Location:   often asymmetric


Prognosis:   may progress during infancy / childhood


Clenched Hand


=  index finger overlaps clenched fist formed by other digits


Cause:    trisomy 18, akinesia-hypokinesia syndromes, temporarily closed normal fist


√  proximal interphalangeal articulation of index finger flexed + ulnarly deviated


√  adducted thumb


Clinodactyly


=  fixed abnormal deviation of 5th finger in radioulnar plane (= radial angulation of DIP joint) ← abnormally small size of middle phalanx


Cause:    trisomy 21 (in up to 60%), triploidy; isolated familial clinodactyly; normal in 18%


Clubhand


=  permanently deviated axis of wrist + usually closed hand


Classification:


(a)  Radial clubhand associated with preaxial deficits (ranging from mild hypoplasia of thumb to complete absence of radius)


(b)  Ulnar clubhand ← ulnar deficiency


Ectrodactyly


=  SPLIT / CLEFT HAND = LOBSTER CLAW HAND


=  longitudinal deficiency of central digits


Cause:    EEC (ectrodactyly, ectodermal dysplasia, cleft lip or palate), Roberts syndrome


Pathogenesis:   failure of median apical ectodermal ridge in developing limb bud


May be associated with:   syndactyly, aplasia, hypoplasia of residual phalanges + metacarpals


√  deep V- or U-shaped central defect


DDx:  oligodactyly (= reduced number of well-formed fingers), constrictive amniotic bands


Macrodactyly


=  overgrowth of all structures of affected (commonly radial) fingers


Cause:   proteus syndrome, neurofibromatosis type 1


Phocomelia


=  missing / foreshortened arm / forearm with presence of hand


Cause:


(1)  Thalidomide


(2)  Roberts syndrome = autosomal recessive disorder associated with tetraphocomelia with more severe upper-limb deformities, facial cleft, polyhydramnios


(3)  TAR syndrome


(4)  Grebe syndrome = autosomal recessive disorder associated with marked hypomelia (more severe in lower limbs increasing in severity distally)


Polydactyly


=  presence of supernumerary digits


Incidence:   1÷683 pregnancies;


◊  Most common hand anomaly!


Cause:   trisomy 13, short-rib-polydactyly syndrome, asphyxiating thoracic dystrophy (Jeune syndrome), Smith-Lemli-Opitz syndrome


ULNAR / POSTAXIAL POLYDACTYLY (more frequent)


affecting 5th finger


Cause:   


(1)  Trisomy 13


(2)  Meckel-Gruber syndrome


(3)  Short-rib polydactyly syndrome


(4)  Ellis-van Creveld syndrome


(5)  Smith-Lemli-Opitz syndrome (= intrauterine growth retardation + characteristic high level of 7-dehydrocholesterol)


(6)  Hydrolethalus syndrome (= heart and brain defects, cleft lip / palate, abnormally shaped nose / jaw, incomplete lung development causing stillbirth / death within a few days after birth)


(7)  Bardet-Biedl syndrome = medullary cystic kidney disease without encephalocele, progressive renal dystrophy, obesity, hypogonadism, learning difficulties


RADIAL / PREAXIAL POLYDACTYLY (less frequent)


affecting thumb


Cause:


(1)  Holt-Oram syndrome


(2)  Short-rib–polydactyly syndrome


(3)  Carpenter syndrome


(4)  Trisomy 21


(5)  VACTERL association


(6)  Fanconi anemia


(7)  Orodigitofacial syndrome


POLYSYNDACTYLY


=  association of polydactyly with syndactyly


Syndactyly


=  abnormal connection between adjacent digits


Incidence:   2–3÷10,000 live births


Location:   commonly between 2nd + 3rd digit


Classification:   simple (between soft tissues), complex (between bones), complete (entire length of finger), incomplete (sparing of distal part)


Cause:   Poland sequence, Apert syndrome and other acrocephalosyndactylies, triploidy, Roberts syndrome, familial syndactyly (autosomal dominant, with variable expressivity and incomplete penetrance), constriction band sequence


Trident Hand


=  same length of last 4 fingers


Cause:   various chondrodysplasias


Overlapping Digit


trisomy 18


Hitchhiker’s Thumb


diastrophic dysplasia


Flexion Contractures


trisomy 13 + 18, fetal akinesia deformation sequence


Limb Reduction


congenital varicella, hypoglossia-hyperdactyly syndrome


Amputation


amniotic band syndrome


Drug-induced Musculoskeletal Embryopathy


Thalidomide


=  sedative-hypnotic nonbarbiturate (sold 1954–1961)


Critical period:   34–50 days after most recent menstrual period


•  increased miscarriage, increased stillbirth rate


•  40% increased infant mortality


√  narrowing, disorganization, destruction of joints


√  hemimelia = absence / gross shortening of distal portion of one / more limbs (esp. radius + thumb)


√  phocomelia = attachment of hands + feet to abbreviated arms and legs


√  amelia = congenital absence of one / more arms / legs


√  fusion / absence of paired bones


Anticonvulsant Drugs


Prevalence:   0.4% of pregnancies


Drugs:   valproic acid, carbamazepine, phenytoin, phenobarbital


√  diminished bone mineral density


√  poorly developed diaphyses of long bones


√  anomalies of phalanges:


√  hypoplastic terminal phalanges associated with dysplastic nails


√  hyperphalangism


√  congenital heart disease, cleft lip + palate, urinary tract anomalies, syndromes of dysmorphism, mental retardation


Folic Acid Antagonists


Drugs:   aminopterin, methotrexate


Critical period:   6–8 weeks after conception


√  growth retardation


√  osteoporosis


√  talipes equinovarus, foreshortened extremities, absent digits, syndactyly, anomalous ribs


√  CNS anomalies, cardiac abnormalities


Vitamin A and Retinoids


•  anomalies of external ear, facial dysmorphism


√  CNS, craniofacial, cardiovascular, thymic malformations


√  hydrocephalus, microcephalus


Warfarin


Critical period:   6–9 weeks GA


Frequency:   10%


√  stippled ossification centers in vertebrae, proximal femora, tarsal + carpal bones


FETAL CNS ANOMALIES


Prevalence:   2÷1,000 births in USA; 90% as 1st time occurrence


Recurrence:   2–3% after 1st, 6% after 2nd occurrence


√  ventricular atrium + cisterna magna are two sensitive anatomic markers for normal brain development!


A.  HYDROCEPHALUS


1.   Aqueductal stenosis


2.   Communicating hydrocephalus


3.   Dandy-Walker malformation


4.   Choroid plexus papilloma


B.  NEURAL TUBE DEFECT


Prevalence:   1÷500–600 live births


Risk of recurrence:   3–4%


1.   Spina bifida


2.   Anencephaly


3.   Acrania


4.   Encephalocele (8–15%)


5.   Porencephaly


6.   Hydranencephaly


7.   Holoprosencephaly


8.   Iniencephaly


9.   Microcephaly


10.   Agenesis of corpus callosum


11.   Lissencephaly


12.   Arachnoid cyst


13.   Choroid plexus cyst


14.   Vein of Galen aneurysm


15.   Schizencephaly


Associated with:   trisomy 13 and 18


Increased risk:   low parity, low socioeconomic status, relative infertility, diabetes, obesity, anticonvulsants, folate deficiency


C.  INTRACRANIAL NEOPLASM


1.   Teratoma (> 50%): benign / malignant


Location:   originate from base of skull


2.   Glioblastoma


3.   Astrocytoma


Fetal Ventriculomegaly


Cause:


A.  MORPHOLOGIC ANOMALY (70–80%):


1.   Spina bifida (30–65%)


2.   Dandy-Walker malformation


3.   Encephalocele


4.   Holoprosencephaly


5.   Agenesis of corpus callosum


B.  ABNORMAL KARYOTYPE (10–20%)


C.  VIRAL INFECTION


◊  20–40% of concurrent anomalies are missed by ultrasound!


√  “dangling” choroid plexus


√  width of ventricular atrium > 10 mm


Prognosis:  21% survival rate; 50% with intellectual impairment


Isolated Mild Ventriculomegaly


=  atrial width of 10–15 mm


Prevalence:   1÷700 in low-risk population


◊  Most common brain anomaly on prenatal sonograms


Associated structural anomalies (9%):


periventricular leukomalacia, subependymal / germinal matrix hemorrhage, partial agenesis of corpus callosum, heterotopia, parenchymal dysplasia


Associated chromosomal anomalies:   in 4%


Recommendation:   MR to diagnose associated structural anomalies


Prognosis:   80% with isolated mild ventriculomegaly have normal motor + intellectual function at ≥ 12 months of age


Lemon Sign


=  flat / inwardly scalloped contour of both frontal bones


1.   Spina bifida


Prevalence for fetuses ≤ 24 weeks: 98%


(90–93% sensitive, 98–99% specific, 84% PPV for high-risk population, 6% PPV for low-risk population)


Prevalence for fetuses > 24 weeks: 13%


(disappears in 3rd trimester)


2.   Encephalocele


3.   Agenesis of corpus callosum


4.   Thanatophoric dysplasia


5.   Cystic hygroma


6.   Congenital diaphragmatic hernia


7.   Fetal hydronephrosis


8.   Umbilical vein varix


9.   Normal fetus (in 0.7–1.3%)


Prenatal Intracranial Calcifications


1.   Toxoplasmosis


2.   CMV infection


3.   Tuberous sclerosis


4.   Sturge-Weber syndrome


5.   Venous sinus thrombosis


6.   Teratoma


Cystic Intracranial Lesion


mnemonic:   CHAP VAN


Choroid plexus cyst


Hydrocephalus, Holoprosencephaly, Hydranencephaly


Agenesis of corpus callosum + cystic dilatation of 3rd ventricle


Porencephaly (= schizencephaly)


Vein of Galen aneurysm


Arachnoid cyst


Neoplasm: cystic teratoma


Abnormal Cisterna Magna


Normal size between 15 and 25 weeks MA:


> 2 to < 10 mm (usually 4–9 mm) in 94–97% of fetuses


A.  SMALL CISTERNA MAGNA + “banana” sign


1.   Chiari II malformation (with myelomeningocele)


2.   Occipital cephalocele


3.   Severe hydrocephalus


B.  LARGE CISTERNA MAGNA


1.   Megacisterna magna


√  cerebellum + vermis remain intact


2.   Arachnoid cyst


√  en bloc displacement of cerebellum + vermis


3.   Cerebellar hypoplasia


4.   Dandy-Walker syndrome (with vermian agenesis)


FETAL ORBITAL ANOMALIES


Hypotelorism


1.   Holoprosencephaly


2.   Chromosomal abnormalities: trisomy 13


3.   Microcephaly, trigonocephaly


4.   Maternal phenylketonuria


5.   Meckel-Gruber syndrome


6.   Myotonic dystrophy


7.   Williams syndrome


8.   Oculodental dysplasia


Hypertelorism


1.   Median cleft syndrome: cleft lip / palate


2.   Craniosynostosis: Apert / Crouzon syndrome


3.   Pena-Shokeir syndrome


4.   Frontal / ethmoidal, sphenoidal encephalocele


5.   Dilantin / phenytoin effect


Orbital and Periorbital Masses


1.   Dacryocystocele


2.   Anterior encephalocele


3.   Glioma


4.   Hemangioma


5.   Teratoma


FETAL NECK ANOMALIES


1.   Cervical myelomeningocele


2.   Occipital cephalocele


3.   Cystic hygroma / lymphangioma


4.   Teratoma


5.   Branchial cleft cyst


6.   Enlarged thyroid


7.   Sarcoma


Nuchal Skin Thickening


=  NUCHAL SONOLUCENCY / FULLNESS / EDEMA


=  skin thickening of posterior neck measured between calvarium + dorsal skin margin


(a)  ≥ 3 mm during 9–13 weeks MA


(b)  ≥ 5 mm during 14–21 weeks MA


(c)  ≥ 6 mm during 19–24 weeks MA


◊  The smallest measurement should be used!


Image plane:   axial / transverse image (slightly craniad to that of the BPD measurement) that includes cavum septi pellucidi, cerebellar hemisphere and cisterna magna (transcerebellar diameter view)


Prevalence:   among the most common anomaly in 1st trimester + early 2nd trimester


Cause:


A.  NORMAL VARIANT (0.06%)


B.  CHROMOSOMAL DISORDERS trisomy 21 (in 45–80%), Turner syndrome (45 XO), Noonan syndrome, trisomy 18, XXX syndrome, XYY syndrome, XXXX syndrome, XXXXY syndrome, 18p-syndrome, 13q-syndrome


◊  30–40% of fetuses with Down syndrome have nuchal skin thickening!


C.  NONCHROMOSOMAL DISORDERS


1.   Multiple pterygium syndrome = Escobar syndrome


2.   Klippel-Feil syndrome: fusion of cervical vertebrae, CHD, deafness (30%), cleft palate


3.   Zellweger syndrome = cerebrohepatorenal syndrome: large forehead, flat facies, macrogyria, hepatomegaly, cystic kidney disease, contractures of extremities


4.   Robert syndrome


5.   Cumming syndrome


√  larger lymphangiomas with radiating septations are usually found with trisomy 18


√  nuchal fullness ≥ 3 mm during 1st trimester is seen in trisomy 21 / 18 / 13 (30–50% PPV)


√  often reverting to normal by 16–18 weeks


√  septations within nuchal translucency carries a 20- to 200-fold risk for chromosomal anomalies compared with normal


Sensitivity:   2–44–75% for detection of trisomy 21


Specificity:   99% for detection of trisomy 21


PPV:   69%


Positive screen:   1.2–3.0% in general population (exceeding 0.5% risk of amniocentesis)


False positives:   0.5–2–8.5%


OB management:   thorough sonographic evaluation at 18–20 weeks MA


DDx:  chorioamnionic separation


Protruding Tongue


1.   Macroglossia


2.   Lymphangioma of the tongue


Macroglossia


1.   Beckwith-Wiedemann syndrome


2.   Down syndrome


3.   Hypothyroidism


4.   Mental retardation


FETAL CHEST ANOMALIES


Pulmonary Underdevelopment


Pulmonary Aplasia


=  rudimentary bronchus ending in blind pouch + absence of parenchyma + vessels


Frequency:   1÷10,000; R÷L = 1÷1


CT:


√  diffuse opacification of involved hemithorax


√  ipsilateral mediastinal shift


√  absence of ipsilateral pulmonary tissue + artery


√  bronchus terminates in dilated short blind pouch


Pulmonary Hypoplasia


=  completely formed but congenitally small bronchus with rudimentary parenchyma + small vessels


Cause:


A.  PRIMARY / idiopathic pulmonary hypoplasia (rare)


B.  SECONDARY pulmonary hypoplasia limiting space for lung development


(a)  Intrathoracic lung compression


1.   Intrathoracic mass


2.   Mediastinal mass


3.   Large hydrothorax


4.   Lymphatic malformation


5.   Agenesis of diaphragm


(b)  Extrathoracic lung compression (= Potter syndrome)


1.   Prolonged oligohydramnios (20–25%) ← renal agenesis, bilateral cystic renal disease, obstructive uropathy, premature rupture of membranes


2.   Fetal ascites


(c)  Dysplasia of thoracic cage


1.   Jeune


2.   Thanatophoric dystrophy


3.   Ellis-van Creveld


4.   Severe achondroplasia


(d)  Others ← reduced breathing activity


1.   Muscular disease


2.   Neurologic condition


3.   Chromosomal abnormality


Path:  absolute decrease in lung volume / weight for GA


√  thoracic circumference (TC) < 5th percentile for EGA


√  TC÷AC length ratio < 0.32


√  FL÷AC ratio < 0.16


√  small hyperlucent lung ← oligemia


√  diminutive ipsilateral pulmonary artery


√  hyperlucent contralateral lung ← compensatory hyperexpansion


√  ipsilateral mediastinal shift


Congenital Chest Malformation


1.   Congenital pulmonary airway malformation


2.   Congenital diaphragmatic hernia (CDH)


3.   Bronchopulmonary sequestration (BPS)


4.   Congenital hydrothorax


5.   Congenital lobar emphysema


6.   Congenital high airway obstruction syndrome


Intrathoracic Mass


in order of frequency:


1.   Congenital diaphragmatic hernia / eventration


2.   Congenital pulmonary airway malformation


3.   Bronchopulmonary sequestration


4.   Bronchogenic cyst


5.   Bronchial atresia


Unilateral Chest Mass


1.   Congenital diaphragmatic hernia


2.   Congenital pulmonary airway malformation


3.   Bronchopulmonary sequestration


4.   Bronchogenic cyst


5.   Unilateral bronchial atresia / stenosis


Bilateral Chest Masses


1.   Laryngeal / tracheal atresia


√  pulmonary hyperplasia


√  symmetrically enlarged echogenic lungs


√  dilated fluid-filled trachea + bronchi


√  inverted hemidiaphragms


√  diminutive heart amongst enlarged lungs


√  ± hydrops


2.   Congenital high airway obstruction


2.   Bilateral congenital pulmonary airway malformation


3.   Bilateral congenital diaphragmatic herniae


Mediastinal Mass


1.   Goiter


2.   Cystic hygroma


3.   Pericardial teratoma


4.   Neuroblastoma


Cystic Chest Mass


1.   Bronchogenic cyst


2.   Enteric cyst


3.   Neurenteric cyst


4.   Cystic adenomatoid malformation type I


5.   Congenital diaphragmatic hernia


6.   Pericardial cyst


7.   Mediastinal meningocele


Complex Chest Mass


1.   Congenital diaphragmatic hernia


2.   Congenital pulmonary airway malformation


3.   Bronchopulmonary sequestration


4.   Complex enteric cyst


5.   Pericardial teratoma


Solid Chest Mass


1.   Congenital diaphragmatic hernia: bowel ± liver


2.   Cystic adenomatoid malformation type III


3.   Pulmonary sequestration


4.   Obstructed lung ← bronchial atresia, laryngeal atresia, bronchogenic cyst


5.   Bronchopulmonary foregut malformation


6.   Pericardial tumor


7.   Heterotopic brain tissue


Regressing Fetal Chest Mass


1.   Cystic adenomatoid malformation


2.   Bronchopulmonary sequestration


Chest Wall Mass


1.   Hemangioma


2.   Cystic hygroma


3.   Teratoma


4.   Hamartoma


5.   Thoracic myelomeningocele


Pleural Effusion


1.   Primary idiopathic chylothorax (most common)


2.   Hydrops fetalis (multiple causes)


3.   Chromosome anomaly: trisomy 21, 45 XO (mostly)


4.   Pulmonary lymphangiectasia / cystic hygroma


5.   Lung mass: cystic adenomatoid malformation, bronchopulmonary sequestration, congenital diaphragmatic hernia, chest wall hamartoma (uncommon)


6.   Pulmonary vein atresia


7.   Idiopathic


FETAL CARDIAC ANOMALIES


Prevalence:   1÷125 births = 0.8% of population; most common of all congenital malformations (40%)


◊  90% occur as isolated multifactorial traits with a recurrence risk of 2–4%


◊  10% are associated with multiple birth defects


◊  responsible for 50% of childhood deaths from congenital malformations


Antenatal sonographic diagnosis to prompt cardiac evaluation:


A.  ABNORMALITIES IN CARDIAC POSITION


B.  CNS


1.   Hydrocephalus


2.   Microcephaly


3.   Agenesis of corpus callosum


4.   Encephalocele: Meckel-Gruber syndrome


C.  GASTROINTESTINAL


1.   Esophageal atresia


2.   Duodenal atresia


3.   Situs abnormalities


4.   Diaphragmatic hernia


D.  VENTRAL WALL DEFECT


1.   Omphalocele


2.   Ectopia cordis


E.   RENAL


1.   Bilateral renal agenesis


2.   Dysplastic kidneys


F.  TWINS


1.   Conjoined twins


Prenatal Risk Factors for Congenital Heart Disease


A.  FETAL RISK FACTORS


1.   Symmetric IUGR


2.   Arrhythmias


(a)  fixed fetal bradycardia (50%) ≤ 110 bpm


(b)  tachycardia (low risk)


(c)  irregular: PACs, PVCs (low risk)


3.   Abnormal fetal karyotype: CHD in Down syndrome (40%); in trisomy 18 / 13 (> 90%); in Turner syndrome (35%)


4.   Extracardiac somatic anomalies by US: omphaloceles (20%), duodenal atresia, hydrocephaly, spina bifida, VACTERL


5.   Nonimmune hydrops (30–35%)


6.   Oligo- / polyhydramnios


B.  MATERNAL RISK FACTORS


1.   Maternal heart disease (10%)


2.   Insulin-dependent diabetes mellitus (4–5%)


3.   Phenylketonuria (in 15% if maternal phenylalanine > 15%)


4.   Collagen vascular disease: SLE


5.   Viral infection: rubella


6.   Drugs


(a)  phenytoin: in 2% PS, AS, coarctation, PDA


(b)  trimethadione: in 20% transposition, tetralogy, hypoplastic left heart


(c)  sex hormones (in 3%)


(d)  lithium (7%): Ebstein anomaly, tricuspid atresia


(e)  alcohol (25% of fetal alcohol syndrome): VSD, ASD


(f)  retinoic acid = isotretinoin (?15%)


7.   Paternal CHD (risk uncertain)


C.  MENDELIAN SYNDROMES


1.   Tuberous sclerosis


2.   Ellis-van Creveld syndrome


3.   Noonan syndrome


D.  FAMILIAL RISK FACTORS FOR RECURRENCE OF HEART DISEASE



















overall incidence : 6–8÷1,000 live births
affected sibling : 1–4% (risk doubled)
affected parent : 2.5–4%

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Jun 29, 2017 | Posted by in GENERAL RADIOLOGY | Comments Off on AND GYNECOLOGY
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