Obstetric Flashcards
Define:
Embryo and Fetus
Embryo: 0-10 weeks (menstrual age)
Fetus: > 10 weeks
Menstrual age: Embryological age + 14 days
Define
Threatened vs inevitable vs incomplete vs complete vs missed abortion:
- Threatened: Bleeding with closed cervix.
- Inevitable: Cervical dilation +/- placental +/- fetal tissue protruding out.
- Incomplete: Residual products in uterus
- Complete: All products out
- Missed abortion: Fetus is dead but still in uterus.
What is the name of the early gestational sac sign?
Intradecidual sign- when seen covered by echogenic decidua is an early sign of early pregnancy (4.5 weeks)
Double decidual sac sign: It is produced by visualising the layers of decider
When should you be able to see the yolk sac?
Yolk sac is the first thing visible within the GS. It should be visible when GS is 8mm in diameter.
The appearance of yolk sac
Should not be too big > 6mm, or too small < 3mm
Should not be solid or calcified.
What is an amniotic band syndrome?
The amnion and chorion are separated by a thin layer of fluid, until 14-16 weeks at which point, they fuse.
If the amnion gets disrupted before 10 weeks, the fetus might get trapped across the fibrous bands- can cause limb amputation.
What is the name of the earliest visualisation of the embryo?
Double bleb sign: this is two fluid filled sacs (yolk and amniotic) with the flat embryo in the middle.
When is embryo usually visible?
Usually at 6 weeks
What is usually used to estimate gestational age in first trimester?
How about in 2 or 3rd trimester?
1st trimester: CRL ( Crown Rump Length)
2nd and 3rd trimester: Composite GA: BPD, AC, HC, and FL
What does anembryonic pregnancy mean?
This is GS without embryo:
- Very early pregnancy
- Non viable pregnancy
You should see yolk sac at 8mm
When would you see a pseudogestational sac?
This is seen in ectopic pregnancy: blood in the uterine cavity with bright decidual endometrium.
What are the diagnostic features of failed pregnancy: (4)
- CRL > 7mm with no heart beat
- Mean sac diameter > 25mm and no embryo
- No embryo with heartbeat > 11 days after a scan that showed GS with a YS
- No embryo with heartbeat > 14 days after a scan that showed GS without a YS
What does subchorionic haemorrhage mean?
These are very common. The % of placental detachment is the prognostic factor associated with fetal demise.
Haematoma > 2/3 of the circumference of chorion has x2 increased risk of abortion.
RF for ectopic pregnancy:
PID Tubal surgery Endometriosis Ovulation induction Previous ectopic IUD
Where is the most common location for ectopic?
The isthmus portion of fallopian tube
What would be suspicious for ectopic pregnancy?
Positive BhCG: At around 2000 IU/L you should see a GS
A normal doubling time makes ectopic less likely
Name a sign that is associated with ectopic pregnancy:
Tubal ring sign: echogenic ring which surrounds un ruptured ectopic. 95% specific.
Other signs include: pseudo gestation sac, trilaminar endometrium, thin-walled decimal sac.
What is heterotropic pregnancy?
A baby in uterus and a baby in the tube or other ectopic locations. Rare. Can happen in women with previous bad PID or those that are taking ovulation drugs.
Where would the biparietal diameter is measured from
This is recorded at the level of the thalamus. It is affected by the shape of the skull.
What is the difference between BPD and HC measurement?
Both recorded at the same level. HD does not include the skin, therefore, less affected by the head shape.
Where would the abdominal circumference measured from?
This is recorded at the level of junction of the umbilical vein and left Portal vein.
How is fetal weight estimated?
This is based on:
- BPD and AC or
- AC and FL
What would be indicative of IUGR?
- Estimated fatal weight below 10th percentile
- FL:AC > 23.5
- Umbilical artery systolic: diastolic > 4
If normal doppler - then he is little guy!
What is the most common cause of oligohydramnios during the third trimester?
Fetal growth restriction associated with placental insufficiency
What are the two different types of IUGR?
- symmetrical: this is global growth restriction. It is seen throughout the pregnancy including first-trimester. Has a much worse prognosis because the brain does not develop.
- asymmetrical: normal head with small body (sparing head). This is seen during the 3rd trimester as a result of extrinsic factor.
What are the causes of asymmetrical IUGR?
High BP,
Severe malnutrition
Euler Danlos
What are the causes of symmetrical IUGR?
TORCH infection
Fetal alcohol syndrome/Drug abuse
Chromosome abnormalities
Anaemia
What is biophysical profile used for?
This is used to look for acute and chronic hypoxia
What should happen to the resistance in the umbilical artery as the gestation age increases?
(Umbilical artery systolic /diastolic ratio)
The resistance in the umbilical artery should decrease with the gestational age.
The general rule is 2 - 3 at 32 weeks.
The ratio should not be more than 3 at 34 weeks.
An elevated systolic to diastolic ratio means there is……….. resistance.
HIGH
High resistance patterns are seen in pre-eclampsia and IUGR.
What is Erb’s palsy?
This is injury to the upper trunk of the brachial plexus (C5-C6), most commonly seen in shoulder dystocia ( which kids with macrosomia are higher risk for)
What is an amniotic fluid index?
This is made by measuring the vertical height of the deepest fluid pocket inch quadrant of the uterus then summing the 4 quadrants. Normal is 5- 20.
What is oliogohydramnios?
This is defined as AFI < 5 cm
Define polyhydramnios?
This is defined as AFI > 20 m or a single fluid pocket > 8 cm.
What does an artery adjacent to the bladder mean?
Two vessel cord
The midgut normally herniates into the umbilical cord around ……. weeks
9-11 weeks
Do NOT call it omphalocele
When can you first see the placenta
around 8 weeks- should be shaped like a disc around 12 weeks.
Ddx for too thin placenta: (6)
Placental insufficiency Maternal hypertension Maternal DM Trisomy 13 Trisomy 18 Toxaemia of pregnancy
Ddx for too thick placenta: (6)
Fetal hydrops Maternal DM Severe maternal anaemia Congenital fetal cancer Congenital infection Placental abruption
Bilobed placenta
2 near equal sized lobes.
Increased risk of type 2 vasa praevia, PPH from trained placenta and velamentous insertion of the cord
Succenturiate lobe
1 or more small accessory lobes.
Increased risk of type 2 vasa praevia, PPH from trained placenta.
Circumvallate placenta
Rolled placental edges with smaller chorionic plate. High risk for placental abruption and IUGR
Re Placenta previa
- Define:
- BUZZWORD
- Practical pearl
This is low implantation of that placenta covering part or all of internal cervical os.
BUZZWORD: painless vagina bleeding in the third trimester
- Empty bladder scanning- Full bladder creates a false positive
Placental abruption:
- Define
- Tips in history
- BUZZWORD
This is premature separation of placenta from myometrium.
tips: mom might be doing cocaine, they might be history of hypertension
BUZZWORD: disruption of the retroplacental complex
Placental abruption vs myometrial contraction/ fibroid
Placental abruption will DISRUPT the retroplacental complex of blood vessel.
Myometrial contraction/fibroid Will DISPLACE the retro placental complex.
Placental Creta
- Define:
- RF?
- BUZZWORD/ Sign
This is abnormal insertion of placenta which invades the myometrium.
RF: previous C section, placenta previa, Advanced maternal age.
BUZZWORD: moth eaten, Swiss cheese appearance of the placenta with vascular channels extending from the placenta into myometrium ( with turbulence flow on Doppler). Thinning (<1mm) of the myometrium is another sign.
What are the 3 different types of placenta creta?
- Accreta: mot common (75%). The villi attach to the myometrium without invading.
- Increta: Villi partially invade the myometrium
- Percreta:Villi penetrate through the myometrium or beyond the serosa. sometimes there is invasion of the bladder or bowel.
What is placenta chorioangioma?
This is hamartoma of the placenta and is the most common benign tumour of the placenta.
These are usually well circumscribed hypo echoic masses near the cord insertion. Flow within the masses pulsating at the fetal heart rate is diagnostic - they are perfused by fetal circulation
What is the diagnosis ?
well circumscribed hypo echoic masses near the cord insertion. Flow within the masses pulsating at the fetal heart rate is diagnostic - they are perfused by fetal circulation
placenta chorioangioma
What is the consequence of large > 4cm and multiple placenta chorioangioma?
Thy can sequester platelets and cause a high output failure- hydrops.
Placental chorioangioma vs placental haematoma:
placenta chorioangioma has pulsating doppler flow.
Haematoma does NOT have pulsating doppler flow.
Two vessel cords seen in these two conditions:
Twin pregnancies
Maternal diabetes
Increase association with chromosomal anomaly and fetal malformation.
Define Velamentous cord insertion
This is when the cord inserts into the fetal membrane outside the placental margin and then has to travel back through the membranes to the placenta (bwn amnion and chorion).
Where is Velamentous cord insertion usually seen? increased risk of?
More common with twin pregnancies: increase risk of IUGR and growth discordance among twins.
Marginal cord insertion:
This is almost a velamentous insertion (cord is within 2cm of the placental margin). It is seen more in twin pregnancies.
Vasa previa:
Define
Types:
Fetal vessels cross the internal os. Two types:
- fetal vessels connect to a velamentous cord insertion within the main body of the placenta.
- Fetal vessel connect to a bilobed placenta or succenturiate lobe.
Umbilical cord cyst:
false cysts vs true cysts (less common)
Omphalomesenteric duct cysts usually peripheral.
Allantoic cysts are central.
If the umbilical cysts persists into 2nd or 3rd trimester, what would it mean?
associated with Trisomy 18 and 13.
When is nuchal lucency measured?
Significance?
it is measured between 9-12 weeks. The anechoic area bwn neck and occiput and the skin should be < 3mm.
> 3mm ~ Downs syndrome - Trisomy 21.
Most common intra abdominal pathology associated with DS:
Duodenal atresia
Most common congenital heart disease associated with DS:
AV canal and VSD
Ddx for echogenic bowel:
Non specific: DS Obstruction Infection CF Ischaemia
Choroid plexus cyst:
Trisomy 18 and 21 ( DS)
Turners
Klinfelters
Nuchal fold thickness > 6mm in second trimester:
DS
Turners
Hydrops: Causes:
Most common cause is Rh sensitisation from previous pregnancies. TORCH Turners twin related stuff Alpha Thalasseamia
Hydrops, uss findings:
Two of the following:
- Pleural effusion
- Pericardial effusion
- Subcutaneous oedema
Lemon sign: Indented frontal bone, classically seen as a sign of …..
Chiari II and also spina bifida
When is lemon sign usually seen?
before 24 weeks.
It is a sign of Chiari II and spina bifida.
Name 2 signs associated with Chiari II and spina bifida:
- Lemon sign: indentation of frontal bone
2. Banana sign: Cisterna magna is obliterated and the cerebellum looks like a banana.
Finding of Spina bifida:
Lemon and banana signs and Small biparietal diameter and ventricular enlargement.
Complex cystic mass in posterior neck in antenatal period
Cystic hygroma- associated with DS and turners
Most common cause of non communicating hydrocephalus in a neonate:
Aqua ductal stenosis
signs of ventriculomegaly:
- Ventricular atrium diameter > 10mm
2. Dangling choroid - of the wall more than 3mm
Define anencephaly
Total absence of the cranial vault and brain above the level of the orbits- not compatible with life.
What is the diagnosis?
pleural effusion, pericardial effusion and ascites in neonates:
Hydrops
What is congenital diaphragmatic hernia is associated with?
Pulmonary hypoplasia
What is tacky and bradycardia in neonates
Tachycardia : HR > 180 bpm
Bradycardia : HR < 100 bpm
Double bubble sign:
Duodenal atresia
What is bowel echogenicity is compared with?
Normal bowel is iso-echoic to the liver
If it is equal to the iliac crest bone - too bright.
ARPKD
Enlarged belated kidneys with oligohydramnios
Posterior urethral valve:
Bilateral hydro on fetal uss or 3rd trimester MRI
Short femur
short femur < 5th percentile: skeletal dysplasia
What happens to fibroid during pregnancy?
Grow in early pregnancy due to oestrogen.
Progesterone in later pregnancy inhibits growth.
RF for uterine rupture:
most commonly in 3rd trimester at the site of previous C section.
Unicornuate uterus, prior uterine curattage and interstitial implantation.
HELLP syndrome:
Haemolysis Elevated liver enzyme Low Platelets - severe form of pre eclampsia 20-40% DIC
Peripartum cardiomyopathy
Define
MRI
This is dilated cardiomyopathy that is seen last month of pregnancy to 5 months post partum.
MRI:
- Global depressed function
- Non vascular territory subepicardial late Gd enhancement
Sheehan syndrome:
This is pituitary apoplexy in post partum female who suffer from large volume haemorrhage. Pituitary grows during pregnancy, if there is an acute hypotensive episode- can stroke it out.
MRI appearance of sheehan syndrome
Acute: T1 bright
Chronic: Ring enhancement around empty sella
Ovarian vein thrombophebitis
post partum fever and pain
R > L
