Large for Dates Flashcards
Define large for dates
Symphyseal-fundal height >2cm for gestational age
Estimated foetal weight >90th centile
State five causes for large for dates
- wrong dates
- foetal macrosomia
- polydramnios
- diabetes
- multiple pregnancy
What does an USS of foetal macrosomia show?
Estimated foetal weight >90th centile
Abdominal circumference >97th centile
How is foetal macrosomia managed?
Exclude diabetes
Reassure
Conservative/induction/C-section
What are the NICE guidelines for delivery of macrosomic babies?
Absence of other indications do not induce labour purely because of macrosomia
What are the risks of macrosomia?
Dr/maternal anxiety Labour dystocia Shoulder dystocia Diabetes Post-partum haemorrhage
What is the name for excess amniotic fluid?
Polyhydramios
How is excess amniotic fluid quantified?
Amniotic fluid index >25cm
Deepest pool >8cm
What can cause polyhydramios?
Maternal - diabetes
Foetal
- anomaly - GI atresia, cardiac, tumours
- monochorionic twin pregnancy
- hydros fetalis
- viral infection (toxoplasmosis, CMV, erythrovirus B19)
What are the symptoms of polyhydramios?
Abdominal discomfort
Pre-labour rupture of membranes
Preterm labour
Cord prolapse
What are the signs of polyhydramios?
Large for dates
Malpresentation
Shiny, tense abdomen
Inability to feel foetal parts
How is polyhydramios diagnosed?
Ultrasound - AFI >25cm, DVP >8cm
What are the investigations for polyhydramios?
Oral glucose tolerance test
Serology (toxoplasmosis, CMV, parvovirus)
Antibody screen
USS - foetal survey
How is polyhydramios managed?
Induce labour by 40 weeks
Serial USS to assess growth, presentation
What are the labour risks of polyhydramios?
Risk of malpresentation
Cord prolapse
Preterm labour
PPH
Define multiple pregnancy
Presence of more than one foetus
What are the risk factors for multiple pregnancy?
Assisted conception African Geography Family History Increased maternal age Increased parity Tall women
Define zygosity
Whether the foetus’ have developed from a single ovum or different ova
What is the difference between monozygosity and dizygosity?
Mono - splitting of a single fertilised egg
Di - fertilisations of two ova by two spermatozoa
Define chrionicity
Number of placenta
Name the four variations of monozygosity
Dichorionic diamnitoic
Monochorionic diamniotic
Monochorionic monoamnitoic
Conjoined twins
What chorionicity is dizygous always?
Dichorionic diamniotic
When can chorionicity and zygosity be determined?
Shape and thickness of membrane at booking scan
What two signs can be seen on ultrasound to determine the chorionicity?
Lamdba - di
T sign - mono
What type of twins are at higher risk?
Monochorionic/monozygous
What are the signs/symptoms of multiple pregnancy?
Exaggerated pregnancy symptoms
Signs - high AFP, large for dates uterus, multiple fetal poles
State the fetal complications of multiple pregnancy
Congenital anomalies, intrauterine death, preterm birth, growth restriction, cerebral palsy, twin to twin trasfusion
State the maternal complications of multiple pregnancy
Hyperemesis gravidarum Anaemia Pre-eclampsia C-section Antepartum haemorrhage Diabetes
What medications should be given to patients with multiple pregnancy?
Iron supplements, low dose aspirin, folic acid
How many ultrasounds will a multiple pregnancy patient have?
MC - 2 weekly from 16 weeks
DC 4 weekly
If the pregnancy is monochorionic monoamniotic what is the management?
Deliver by c-section at 32-34 weeks
State the complications of monochorionic twins
- single fetal death
- selective growth restriction
- twin anaemia polycythaemia
- absent/reversed end diastolic flow
- twin to twin transfusion
How is single fetal death managed?
MRI 4 weeks post IUD and MCA US to check for fetal anaemia. Risk of death and neurological abnormality to the survivor are high.
If abnormal doppler is found on selective growth restriction what may be required?
Selective reduction
What is twin anaemia polycythaemia sequence?
Imbalance in blood levels between the two babies
What can cause twin anaemia polycythaemia sequence?
Spontaneously
Following laser ablation for TTTS
How is twin anaemia polycythaemia sequence diagnosed?
US of middle cerebral artery peak systolic velocity
Define twin to twin transfusion syndrome
Syndrome with artery-vein anastomoses, donor twin perfuses the recipient twin
How is twin to twin transfusion diagnosed?
Oligohydramios - donor
Polyhydramios - recipient
What are the complications of twin to twin transfusion?
Mortality >90% with no treatment
Neurological morbidity
How is twin to twin transfusion treated?
<26/40 weeks fetoscopic last ablation
>26/40 weeks amnioreduction/septostomy
When should babies with twin to twin transfusion be delivered?
34-36 weeks
What is the risk of C-section in multiple pregnancy?
50% greater risk of c-section
What are the indications for c-section in multiple pregnancy?
MCMA
Triplets or more
Describe labour in multiple pregnancy
Epidural Fetal monitoring (USS,FSE) Synthetic oxytocin after twin 1 USS for presentation <30 mins between deliveries
Define gestational diabetes
Carbohydrate intolerance resulting in hyperglycaemia of variable severity with onset/first recognition during pregnancy
What are the fetal complications of maternal diabetes?
Congenital anomalies, miscarriage, IUD, worsening diabetic complications, pre-eclampsia, polyhydramios, macrosomia, shoulder dystocia, neonatal hypoglycaemia
How is T1/T2 DM managed in pregnancy?
Low dose aspirin from 12 weeks
Fetal anomaly scan 18-20weeks
Growth scan 4 weekly
Deliver at 38 weeks
What are the risk factors for gestational diabetes?
Previous GDM (50% recurrence) BMI >30 Family history - mum or sister Ethnic variation Previous big baby Big baby Glycosuria
Describe the pathogenesis of gestational diabetes
HPL and cortisol cause placental hormones to induce insulin resistance/deficiency causing overgrowth of sensitive tissues
How is gestational diabetes investigated?
BG monitoring, OGTT 24-28 weeks
What is the diagnostic fasting and 2 hour glucose for gestational diabetes?
Fasting >5.1/5.6
2 hour >8.5/7.8
What are the target values for fasting glucose and 1 hour?
Fasting 3.5-5.5
1 hour <7.8
What does delivery date depend on in diabetics?
Management
Describe the different delivery dates for diabetics
Insulin 38-39 weeks
Metformin 39-40 weeks
Diet 40-41 weeks
Macrosomia/PET/IUGR - earlier delivery
When is a c-section indicated in diabetes?
EFW >4.5kg
What is the risk of post natal T2DM after gestational diabetes?
Up to 70%
What are the risk factors for post natal T2DM?
Obesity, use of insulin in pregnancy, ethnic group, OGTT fasting levels, IGT post partum
When are bloods checked post natally?
6-8 weeks fasting/OGTT
