OBS DDx Flashcards
Causes of asymmetric IUGR:
Placental insufficiency
High BP / PET
Ehler Danlos
Severe malnutrition
Usually only seen in 3rd trimester
Causes of symmetric IUGR:
TORCH infection
Fetal Alcohol syndrome
Drug abuse
Chromosomal abnormalities
Usually seen throughout pregnancy
Bilobed placenta:
Two near equal size lobes connected by thin strip.
Risks:
- vasa previa
- Post partum haemorrhage
- Velamentous insertion
Succenturiate lobe:
One or more small accessory lobes.
Risks:
- vasa previa
- post partum haemorrhage
Circumvallate placenta:
Rolled placenta edges with smaller chorionic plate
Risks:
- placental abruption
- IUGR
Thin placenta:
< 1cm thick Causes: - Placental insufficiency - Maternal HTN - Maternal DM - T 13 - T 18 - PET
Thick placenta:
> 4cm thick Causes: - Hydrops - Maternal DM - Severe maternal anaemia - Infection - Abruption
Placenta abruption
Painful bleeding
Pre mature seperation of placenta from myometrium / retroplacental complex.
Placenta previa:
Painless bleeding 3rd trimester.
Low implantation of placenta:
- Low lying: making within 2cm of internal os
- Marginal: extends to edge of internal os but doesn’t cover
- Complete: covers internal os
- Central: centered over internal os.
normal > 3cm from os.
Placenta accreta:
Villi attach to myometrium, without invading
“A: Attach”
Placenta Increta:
Villi partially invade the myometrium
“I: Invade”
Placenta Percreta:
Villi penetrate through myometrium or beyond into adjacent organs; bowel / bladder.
“P: Penetrate”
Velamentous cord insertion:
Cord inserts into fetal membranes outside placental margin.
More common in twins
Increased risk of IUGR
Vasa Previa:
Fetal vessels cross or almost cross the internal cervical os.
Type 1: fetal vessels connect to velamentous cord insertion within the main placental body
Type 2: fetal vessels connect to bilobed placenta or succenturiate lobe.
Doppler values:
Normal values at any 28 - 40 weeks scan:
AFI: 10 - 20
UA PI: < 1.1
MCA PI: > 1.7
CPR: > 1.7
Abnormal doppler order:
Before 34 weeks:
- Abnormal dopplers occur in order
- Increased UAPI, followed by reduced MCA PI and CPR followed by increased DV PI.
After 34 weeks:
- abnormal dopplers not in order.
- Low MCA PI or CPR can be isolated, and associated with increased risk of lactic acidosis
Trisomy 21 Features:
Absent Nasal Bone
Increased nuchal fold (2nd trimester weeks 15 - 21, >6mm)
Increased nuchal translucency (1st trimester, abnormal > 3mm)
Microcephaly
Cystic hygroma
Congenital heart disease: AVSD, VSD
Echogenic heart focus.
Duodenal atresia
Gastric atresia
Echogenic bowel
Renal dilation
Short femur / humerus
Hypoplasia middle phalanx little finger / Clinodactyly.
Sandal gap
Trisomy 18 Features:
Strawberry skull Choroid plexus cysts Facial cleft Micronathia Absent NB Increased nuchal fold Dandy Walker malformation
Cardiac anomalies: VSD
Diaphragmatic hernia
Omphalocele
Horse shoe kidney, hydroneprhosis.
Club foot, rocker bottom foot.
Clenched hand / over lapping fingers.
Trisomy 13 Features:
Absent Nasal bone Increased nuchal fold Cleft lip / palate Holoprosenchepaly Encephalocele
Congenital heart disease.
Omphalocele.
Diaphragmatic hernia
Horse shoe kidney, Polycystic kidney
Polydactyly
Beckwith Widermann Sydrome:
Syndrome of over growth
increased risk of child hood cancers, mostly sporadic, 15% AD inheritance.
Wilms tumour risk (most common) Hepatoblastoma risk Heme-Hypertrophy / organomegaly Macroglossia Omphalocele Perinatal hypoglycaemia.
Meckel Gruber:
AR multi organ syndrome
Encephalocele
Renal dysplasia with multiple tiny renal cysts, appear as echogenic kidneys, analogous to ARPKD.
Polydactyly.
Fetal Hydrops:
2 or more: ascites, pleural effusion, pericardial effusion, skin oedema, polhydramnios, placental enlargement.
Immune:
- Fetal haemolytic anaemia: Rh incompatibility.
- Assess MCA VMax. > 65 is elevated.
Non immune:
- Cardiac: structural, arrhythmias
- Extra cardiac shunt: vein of Gale malformation, hepatic haemangioendothelioma, twin twin transfusion.
- Infection: parvovirus, TORCH
- Hepatitis, nephrotic syndrome
- Venous obstruction: turners
- Chromosomal: Turners, T21.
Echogenic Bowel:
Normally bowel iso to liver.
If equal to iliac crests = echogenic bowel.
Normal variant T21 Infection: CMV, parvovirus, toxoplasmosis CF Meconium peritonitis can mimic echogenic bowel Fetal growth restriction Ingested blood. Bowel atresia
Dilated Bowel:
Normal 3rd trimester bowel Duodenal atresia: double bubble jejunal / ill atresia: triple bubble, sausage bowel loops Meconium ileus - CF Anal atresia: VACTERAL Volvulus
Small absent stomach:
Normal transient finding
Oesophageal atresia:
- trachea-oesophageal fistula / VACTERAL
- Late polyhydramnios
- T18 > T21
Congenital diaphragmatic hernia
Severe oligohydramnios
Severe cleft lip.
Abdominal Ca++ Ddx:
Meconium peritonitis: intra peritoneal Ca++ and ascites.
Gall stones
Hepatic Ca++
- Intrahepatic - infection, chromosomal anomalies
- Capsular - meconium peritonitis
Intra luminal Ca++:
- anala atresia +/- urinary tract anomaly VACTERAL.
Teratoma
Increased Nuchal Translucency:
11 - 14 weeks
Normal: < 2.2 - 2.8mm (Age and CRL dependent)
< 2mm: risk <1%
Echogenic kidney Ddx:
ARPCKD:
- eventual renal enlargement bilaterally.
Obstructive cystic dysplasia:
- Urinary tract dilation
Trisomy 13:
- Echogenic and enlarged
- Holoprosenchephaly, cyclopean, cleft lip
- Cardiac defect, IUGR, polydactyly.
Meckel-Gruber:
- renal cystic dysplasia - enlarged
- Encephalocele
- Post axial poly dactyly (ulnar margin)
Beckwith Widerman Syndrome:
- Enlarged kidney, normal morphology and echo texture.
- Macrosomia, macroglosia, omphalocele.
Oligohydramnios:
AFI < 5cm / < 7cm cm in australia
Can cause Potter sequence - facial dysmorphism, pulmonary hypoplasia, club feet, MSK contractures.
Associated with IUGR with / without structure abnormality.
GU malformations:
- Renal agenesis
- Bladder outlet obstruction: posterior urethral valves.
- Ureteropelvic junction obstruction
- Renal dysplasia: ARPCKD: enlarged echogenic kidneys.
Hydronephrosis, fetal bladder not seen:
Cause of oligohydramnios likely renal anomaly. Hydronephrosis: - Less than 4mm always normal, - greater than 10mm always abnormal > 6mm 16 - 20/40 > 8mm 20 - 30/40 > 10mm after > 30/40
Ddx:
- Bilateral multi cystic dysplastic kidneys
- Bilateral renal genesis
- ARPCKD.
Hydronephrosis, hydroureter, normal bladder:
Distal ureteral obstruction / reflux is cause: Hydronephrosis: - Less than 4mm always normal, - greater than 10mm always abnormal > 6mm 16 - 20/40 > 8mm 20 - 30/40 > 10mm after > 30/40
Distal ureteral obstruction of ectopic insertion of upper pole moiety which inserts infers-medially, in duplication.
Ureterocele: dilation of intra mural portion of ureter.
Vesico-ureteric reflux.
Pelvi-Ureteric junction obstruction: (no hydroureter)
- 10% bilateral
- 25% contralateral anomaly
- 10% extra renal anomaly.
Hydronephrosis, hydroureter, dilated bladder:
Bladder outlet obstruction: Hydronephrosis: - Less than 4mm always normal, - greater than 10mm always abnormal > 6mm 16 - 20/40 > 8mm 20 - 30/40 > 10mm after > 30/40
Posterior urethral valves.
- Key hole bladder
- Pulmonary hypoplasia, VACTERAL.
Urethral atresia
Prune Belly syndrome.
- gross pelvi-calyceal and ureteric dilatation with renal dysplasia.
- anterior abdominal wall underdevelopment
- bilateral undescended testes (cryptorchidism) in males
Polyhydramnios:
AFI > 25cm (increased fluid > 20cm - Australia go on 95th centime value for gestation).
Commonly idiopathic with normal fetus
Chromosomal anomalies:
- Turners, T 21, T18.
DM
Structural defects:
- Upper GI:
Laryngeal,
Oesophageal (VACTERAL),
Duodenal atresia (T21).
- Secondary obstruction:
diaphragmatic hernia,
gastroschisis,
omphalocele,
CPAM.
- Severe CNS anomaly
Anencephaly.
- Twin twin transfusion (largest pocket > 8cm)
- Placental abnormality: choriocarcinoma.
Hydrops
Omphalocele:
Midline anterior abdominal wall defect, covered by peritoneum.
Umbilical cord inserts centrally at base of herniated sac.
Associations:
- Cardiac anomalies
- Trisomies
- Beckwith Wiedeman syndrome.
Gastroschisis:
Para umbilical (usually right), anterior abdominal wall defect, without peritoneal covering. Usually isolated finding
Pentalogy of Cantrell:
Ectopia cordis - extra thoracic heart. Pericardial defect Omphalocele Diaphragmatic defect Sternal disruption.
Limb shortening DDX:
Thonatophoric Dysplasia: Type 1: - Normal calverium - Micromelia (entire limb shortening) - Telephone receiver femur - Normal ossification / mineralisation, no fracture. - Platyspondyly, small chest. - Trident Hand
Type 2:
- cloverleaf calverium.
Osteogenesis Imperfecta:
- micromelia (entire limb shortening)
- Decreased ossification / decreased mineralisation
- Multiple fractures
- Improved visualisation of near field brain due to under ossified calverium.
Diabetic Embryopathy:
- Caudal regression - sacral agenesis, tailors posture.
Achondrogenesis.
Abnormal placenta location:
Placenta previa
Placenta accrete spectrum
Succenturiate lobe
Abnormal placental margin:
Marginal placental abruption
Circumvallate placenta
Marginal cord insertion
Abnormal umbilical cord:
Allantoic cyst with patent urachus Omphalomesenteric duct cyst Cystic Wharton Jelly (Aneuploidy) Omphalocele mimics cord cyst Physiologic gut herniation; completed by 12/40 Cord knot - mono amniotic twins.
Solid / echogenic Lung Mass DDX:
CPAM:
- tiny cysts, uniformly echogenic
- Usually single, 1 lobe
- Vascular supply from pulmonary artery.
Bronchopulmonary sequestration:
- Uniformly echogenic, well marginated, triangular mass.
- usually left sided.
- Feeding vessel from aorta
- Draining vessels IVC / azygous.
Congenital Diaphragmatic hernia:
- Liver more hypoechoic
- Bowel more hyper echoic.
Teratoma:
- pericardial effusion
- Ca++
Congenital lobar emphysema.
Cystic Lung Mass Ddx:
If stomach above diaphragm = CDH:
- cystic mass left chest
- Absent stomach
- Right heart deviation
- Polyhydramnios
Stomach below diaphragm: CDH less likely:
Simple cyst:
- Broncogenic cyst
- Neuroenteric cyst
Complex cyst:
- CPAM
- Lymphangioma (extend beyond chest)
- CDH (right sided).
Abnormal Cardiac Axis:
Approach:
Check fetal stomach and heart on left.
- If both on right = situs inversus.
- Opposite sides = heterodoxy syndrome.
Cardiac axis normally 35-45 degrees. If abnormal axis: - Pushed by mass / effusion - Pulled by small lung - Pushed inferiorly by mediastinal mass - Ectopia cordis.
Cardiac structure:
- Atria
- Ventricles
- Crossing outflow tracts
- AV concordance
- Ventricle-arterial concordance.
- 3 vessel view: normal PA - Aorta - SVC with trachea posteriorly.
Congenital heart structural abnormalities: Right heart enlargement:
Shunt lesions, vascular malformation
Placental insufficiency
Left heart outflow obstruction
Congenital heart structural abnormalities: Small Right Ventricle:
Pulmonary atresia / stenosis
Unbalanced AVSD
Congenital heart structural abnormalities: Small left ventricle:
Hypoplastic left heart
Unbalanced AVSD
Congenital heart structural abnormalities: Large right atrium:
Ebstein anomaly
Tricuspid dysplasia
Pulmonary stenosis / atresia
Congenital heart structural abnormalities: Conotruncal malformation:
4 chamber view normal
Single outflow tract = truncus
Parallel outflow tracts = transposition.
Large aorta over riding VSD with seperate small pulmonary artery = TOF
Congenital heart structural abnormalities: Ectopia Cordis
Extra thoracic / intra abdominal heart.
Assess for amniotic bands.
Pentalogy of Cantrell:
- Anterior diaphragmatic hernia
- Midline abdominal wall defect
- Cardiac anomalies
- Diaphragmatic pericardial defect
- low sternal defect.
Intra cranial cyst midline:
Cavum Verge:
- Posterior extension of cave septum pellucid.
Agenesis Corpus Callosum:
- Parallel lateral ventricles
- Colpocephaly, with tear shaped ventricles
- Steer horn configuration frontal horns (coronal)
- Abnormal spoke wheel ACA
- Sagital radial sun ray distribution of gyri
Dandy Walker:
- Vermis hypoplasia
- Cystic dilation 4th ventricle
- Large posterior fossa cyst, continuous with 4th ventricle
- Elevated torcula
Alobar holoprosencephaly:
- mono ventricle
- Absent CSP, absent falx
- Facial anomalies
- T13
Semi lobar / lobar holoprosencephaly:
- Mono ventricle anteriorly
- absent CSP
- Seperation into 2 lobes posteriorly
Arachnoid cyst
Cystic teratoma
Vein of Galen malformation
Arteriovenous fistula.
Intra cranial cyst Lateral location DDX:
Choroid plexus cyst:
- Cyst >2mm within choroid plexus
- incidental, or associated with T18
Arachnoid cyst:
- Extra axial cyst displaces brain
- Avascular, over convexity.
Schizencephaly:
- Wedge shaped defect from lateral ventricle to inner table lined by grey matter.
- Open or closed lip.
Arteriovenous Malformation
Porencephaly.
Posterior Fossa Cyst DDX:
Normal cerebellum size
- Mega cisterna magna
- arachnoid cyst.
Distorted / compressed / abnormal vermis:
- Arachnoid cyst
- Dandy Walker.
Normal vermis but rotated:
- Blake pouch cyst.
Mega cisterna Magna:
> 10mm, normal cerebellum, T18 association.
Dandy Walker:
- Vermis dysgenesis
- Posterior fossa cyst communicates with 4th ventricle
- Elevated torcula
- Associations: callosal dysgenesis, heterotopic cortical dysplasia, chromosomal anomalies, cardiac anomalies.
Blake Pouch Cyst:
- Elevated rotated Vermis
Arachnoid cyst:
- no 4th ventricle communication
- Vermis intact
Dural sinus malformation
Vein of Galen malformation
Joubert syndrome:
- Molar tooth sign.
Findings diagnostic of pregnancy failure
Findings diagnostic of pregnancy failure
- crown-rump length (CRL) of ≥7 mm and no heartbeat on a transvaginal scan
- mean sac diameter (MSD) of ≥25 mm and no embryo on a transvaginal scan
- absence of embryo with heartbeat ≥2 weeks after a scan that showed a gestational sac without a yolk sac
- absence of embryo with heartbeat ≥11 days after a scan that showed a gestational sac with a yolk sac
- pregnancy with an embryo with no heart activity on initial scan and repeat scan ≥7 days later
- sac with no embryo and an MSD <12 mm on initial scan that fails to double in size on a scan ≥14 days later
- sac with no embryo and an MSD ≥12 mm on initial scan with no embryo heart activity on a scan ≥7 days later
- embryo (irrespective of crown-rump length) without cardiac activity on initial scan and a scan ≥7 days later 2
Findings suspicious but not diagnostic of pregnancy failure
- crown-rump length (CRL) of <7 mm and no heartbeat
- mean sac diameter (MSD) of 16-24 mm and no embryo
- absence of embryo with heartbeat 7-13 days after a scan that showed a gestational sac without a yolk sac
- absence of embryo with heartbeat 7-10 days after a scan that showed a gestational sac with a yolk sac
- absence of embryo ≥6 weeks after last menstrual period
- amnion seen adjacent to yolk sac, with no visible embryo (empty amnion sign)
- enlarged yolk sac (>7 mm)
- small gestational sac in relation to the size of the embryo (<5 mm difference between mean sac diameter and crown-rump length)
large amniotic cavity (expanded amnion sign)
Abnormal cervical length in pregnancy:
Cervical length < 3cm is abnormal.
Fetal ventriculomegaly:
> 10mm
Primary CNS structural causes:
- Aqueductal stenosis
- Dandy Walker
- Chiari II
- Holoprosencephaly
- CC genesis
Genetic:
- T 13
- T18
Destructive
- Infection
- Haemorrhage
- Infarct
Idiopathic.
Normal fetal kidney size:
Grow approx. 1mm per week of gestation, e.g. 20 week fetes should have renal length of 20mm.
Staging twin twin transfusion:
VIVA approach:
- Twin pregnancy
- What type of twin –> T sign = monochorionic; likely will test twin to twin or TRAPs pathology.
- Assess each twin fluid then bladder first, to assess recipient twin and donor twin
- -> Recipient twin, increased amniotic fluid and large bladder
- -> Donor twin, reduced fluid, small / absent bladder.
stage I: oligohydramnios/polyhydramnios
stage II: bladder not visible in donor twin
stage III: abnormal Dopplers in either twin
stage IV: hydrops fetalis in either twin*
stage V: in-utero demise of either twin
*almost always in the recipient; rarely in the donor if there is coexistent TAPS
Single Umbilical artery associations:
IUGR
Umbilical arterial aneurysm
Twin reversed arterial perfusion sequence
When found with other fetal anomalies, it can be also be associated with:
Chromosomal anomalies
- trisomy 21 (12.8% had an SUA),
- trisomy 18 (50% had an SUA),
- trisomy 13 (25% had an SUA)
Persistent right umbilical vein
congenital renal anomalies
- renal agenesis: occurs usually on the side where the artery is absent.
sirenomelia: mermaid syndrome / fusion lower limbs.
velamentous insertion of the cord
