6. Obs and Gyn 2 Flashcards
Give 4 causes of oligohydramnios.
Prolonged pregnancy
Ruptured membranes
FGR
Fetal renal congenital abnormalities
What are the US measurements that would indicate oligohydramnios?
AFI (amniotic fluid index) <5cm
single DVP (Deepest Vertical Pool) <2cm
Explain 3 implications of oligohydramnios.
May cause hypoxia due to cord compression.
If there is concurrent placental dysfunction / FGR may increase risk of stillbirth and hypoxia.
If early may cause pulmonary hypoplasia and pulmonary hypertension.
Give 3 clinical features that would suggest polyhydramnios + indicative measurements.
Large for dates
Tense abdomen
Cannot feel fetal parts
Single DVP >8cm // AFI >90th centile for gestation.
AFI is the measurement of DVP in the four quadrants
Causes of polyhydramnios:
Idiopathic
LGA
Diabetes (fetal polyuria)
Structural problem causing inability to swallow
Chromosmoal / genetic
Placental tumours
Neurological conditions
Give 6 complications of polyhydramnios.
Placental abruption
Malpresentation
Cord prolapse
Need for CS
PPH
Premature birth and perinatal death
Give 5 complications of fetal macrosomia.
Shoulder dystocia
PPH
Tears
IOL option
CS option
Reduced fetal movements can be a sign of fetal hypoxia and attempts to conserve energy or if they are unwell e.g. anaemic. What should a women do if she is concerned about reduced fetal movements.
Call and attend
CTG +/- scan
Ongoing monitoring if continued
If >37 weeks consider delivery
Give 4 risk factors for a twin / multiple pregnancy.
Assisted conception e.g. IVF, ovulation induction
Increased maternal age
FHx
West African origin
Give definitions for each of zygosity, chorionicity & amnionicity.
Zygosity = number of fertilized eggs
Chorionicity = number of placentas
Amnionicity = number of sacs
What is the most common type of twins?
Dizygotic (2 eggs, 2 sperm)
2/3 of twins in the UK
Identical twins are MONOZYGOTIC. Outline the timeline of the split of the one fertilized egg and the outcomes for each.
Splits before day 4; prior to chorion development; dichorionic, diamniotic. 1/3
Splits day 4-8; prior to amnion development; monochorionic, diamniotic. 2/3
Splits from day 9; monochorionic, monoamniotic (risk of conjoined if after day 13). Very rare.
Give 4 fetal risks of multiple pregnancy.
Miscarriage
Congenital anomaly
FGR
Pre-term delivery
Give 3 specific complications of monochorionic twins.
Acute transfusion
Twin-twin transfusion syndrome
TRAPS (twin reversed arterial perfusion sequence)
All maternal complications are increased with increased fetal / placental number. Give 5 particular antenatal complications that are especially important to be aware of.
Hyperemesis gravidarum
GDM
PET
Anaemia
Placenta praevia
Screening for aneuploidy is available for twin pregnancies. Describe the differences in the results for DCDA vs MCDA, and the types of screening available.
DCDA per baby result.
MCDA per pregnancy result.
US (determination of chorionicity +/- gender for each baby is essential for differentiation at further appts).
Amniocentesis
CVS
Describe the US schedule for twins (DC vs MC).
DC; 4 weekly from 24 weeks.
MC; 2 weekly from 16 weeks.
Twin pregnancies should be delivered via elective delivery. Give the preferred weeks of delivery for DCDA vs MCDA.
37 weeks DCDA
36 weeks MCDA
What is the average uterine blood flow at term?
400ml / min
Describe the mechanism of acute transfusion in MC twins and the management.
Death of one twin can lead to increase in HIE / injury / death due to pressure in dead twin causing transfusion / exsanguination of healthy twin into dying one.
Expedite delivery if near term.
If not, monitoring of survivor for anaemia and transfusional brain injury.
Describe the mechanism of twin-twin transfusion syndrome, including incidence and Dx.
Mechanism is chronic net shunting from one twin to another.
Donor twin is growth restricted, oliguric and anhydramniotic.
Recipient twin is polyuria, polyhydramnios, cardiac problems and hydrops present.
Occurs in 15% of MC twins, responsible for 15-20% of perinatal death.
Dx using US: liquor volume, bladder?, cord dopplers, oedema / ascites.
The incidence of breech position at 20 weeks is 40%, reduces to 25% by 32 weeks and is 3-4% at term. Give some associations of breech presentation.
Multiple pregnancy
Bicornuate uterus
Fibroids
Polyhydramnios
Oligohydramnios
Placenta praevia
Fetal anomaly e.g. NTD, NM disorders, autosomal trisomies
What are the 3 types of breech birth position?
Flexed
Footling
Extended
Vaginal delivery from breech position mainly carries risks to the fetus. Outline some of these risks.
Intracranial injury
Widespread bruising
Damage to internal organs
Spinal cord transection
Umbilical cord prolapse
Hypoxia
What are some absolute contraindications to ECV?
CS required regardless, e.g. placenta praevia
Abnormal CTG
APH within last 7 days
Major uterine abnormality
Ruptured membranes
Multiple pregnancy (except in delivery of 2nd twin)
What does ECV stand for, who is it offered to and what is the success rate?
External Cephalic Version
Offered to all women with breech presentation at term if there are no contraindications.
From 36w in nulliparous and 37 in multiparous.
50% success rate, return to breech in <5% of cases after successful ECV.
There are absolute and relative contraindications when considering ECV for a fetus in breech position. Give some relative contraindications.
Morbid maternal obesity
Major fetal anomaly
Nuchal cord
Hyperextended fetal head
Oligohydramnios
FGR
Proteinuric pre-eclampsia
What are the cut offs for low birth weight / very / extremely?
LBW = <2501g
Very LBW = <1501g
Extremely LBW = 1000g
Outline 4 aetiological causes of pre-term birth, with each of their incidences.
Spontaneous labour / cause unknown = 35%
Iatrogenic e.g. maternal HTN, FG problems, antepartum haemorrhage = 25%
PPROM = 25%
Multiple pregnancy = 15%
Women at risk of preterm birth may be offered cervical length surveillance, a cervical suture or progesterone. Outline 5 risk factors for preterm birth.
Previous preterm labour or PROM <34 weeks (strongest indicator).
Previous LLETZ >1cm or multiple.
Previous full dilatation CS.
Previous cervical suture.
Uterine anomaly e.g. bicornuate.
Multiple pregnancy (57% vs 7%)
Preterm delivery before 33 weeks gestation is the leading cause of perinatal morbidity & mortality. Perinatal mortality rates are proportional to immaturity of organ systems, especially the lungs, brain and GIT. Outline some complications associated with preterm birth.
RDS
CP
NEC
Retinopathy
Intraventricular haemorrhage
Maternal corticosteroids are often offered to women during suspected labour, definitely between 24+0 and 33+6. What is the mechanism of these on the lungs, and what other benefits do they have? Give one contraindication.
IM betamethasone / dex
Cross the placenta and increase the amount of pulmonary surfactant produces by type II fetal pneumocytes.
Reduces incidence of RDS by 44%, neonatal death by 31%, also reductions in NEC and NICU admission.
Contraindicated in active maternal sepsis.
What drug is given to for fetal neuroprotection, and what dose is given?
Magnesium sulfate.
Reduces incidence of CP.
<30 weeks give, consider if <32.
4g loading dose, then 1g per hour infusion for up to 24 hours.
What is the definition of stillbirth?
A baby delivered with no signs of life that is known to have died after 24 completed weeks of pregnancy.
What are the two most common stillbirth associations? (50% causes unknown)
Advanced maternal age
Maternal obesity
Give 3 ultrasound features of a stillbirth.
Absence of fetal heartbeat
Spalding sign (overlapping of fetal skull bones)
Hydrops
Stillbirth causes are many, and can be split into 5 different categories. List the 5 categories, and some causes within each category if possible.
Fetal
Maternal
Placental-mediated
Structural
Intra-partum
Outline the difference between low-lying placenta and placenta praevia, as per new NICE guidance.
Low-lying placenta = placenta in lower segment, edge <20mm from internal os.
Placenta praevia = placenta completely covering internal os.
Hamorrhage in labour is inevitable with placenta praevia. Give delivery advice.
LLP <20mm; CS advised, risk of bleeding.
Placenta praevia; CS advised.
Placenta in lower segment but >2cm from os; vaginal delivery may be possible; assess engagement of presenting part etc.
Risks of placenta praevia (3).
Sudden unpredictable major / massive haemorrhage.
Massive haemorrhage at CS due to relatively poor capacity of the lower segment of the uterus to contract.
Morbidly adherent placenta.
Outline the management and delivery advice for placenta praevia.
Recurrent bleeding = 34 to 36+6
Praevia (covering os) = 36-37
Low lying and asymptomatic = ~ 37-39
Could admit from 30-32 weeks until delivery, but often outpatient management if no bleeding.
What is the definition of placental abruption? + describe the risk of only considering revealed blood in anabruption
Retroplacental haemorrhage (bleeding between the placenta and uterus). Usually involves some degree of placental separation.
Revealed blood may not reflect the total blood loss as the haemorrhage may be retroplacental without any external loss, so should always consider in a clinically shocked patient. Concealed abruption is the most hazardous type of abruption.