Answers to Learning Issues
1
The symphysis-fundal height should be within 2cm of that expected for the gestational age. By
definition a large for dates pregnancy is one that is 3 cm or more from that expected for the
gestational age.
2
A large symphysis-fundal height raises the possibility of
Wrong dates
Macrosomia
Multiple pregnancy
Polyhydramnios
Tumours – Fibroid / Ovarian Cyst
When there is a discrepancy between the gestational age and the symphysis fundal height, the dates
should be confirmed. The most common cause of fetal macrosomia is maternal diabetes. The fetus
may also be constitutionally large. It is very rare that a multiple pregnancy is missed on ultrasound
scan, but this should be considered. An increased maternal body mass index may also affect the
symphysis-fundal height. Other pathologies such as fibroids or ovarian cysts may produce a larger
than expected symphysis-fundal height. A full bladder might also falsely suggest a large for dates
pregnancy.
3
The classification of multiple pregnancy is based upon:
The number of fetuses – twins, triplets, quadruplets, etc.
The number of feritilised eggs – Zygosity
The number of placentas – Chorionicity
The number of amnioitic cavities – Amnionicity
All monochorioic twin pregnancies are monozygotic, but not all dichorionic twin pregnancies are
dizygotic.
4
The following are more common in multiple pregancy :
Minor complications of pregnancy EG – nausea, anaemia, heartburn, back pain,
headache
Miscarriage
Fetal abnormailities
Chromosomal defects
Intra-uterine growth restricition
Antepartum Haemorrhage
Pre-eclampsia
Pre-term delivery
Post-partum haemorrhage
Cerebral palsy
Death
Maternal mortality is increased in association with multiple pregnancy. Maternal mortality associated
with multiple pregnancy is approximately twice as high as for singleton pregnancies
Perinatal mortality is also increased in association with multiple pregnancy. Perinatal mortality is
approximately six times higher than for singleton pregnancies. The main contributor to this is preterm delivery.
5
Complications of Monochorionic Twin Pregnancy:
Feto-Fetal Transfusion Syndrome (Twin-to-Twin Transfusion Syndrome)
Death of a co-twin
Twin Reversed Arterial Perfusion Sequence (TRAP Sequence)
Conjoined twins
Cord accident secondary to monoamnionicity
6
The world health organisation (WHO) has defined diabetes as either a fasting blood glucose of >7.8
mmol/L or a level >11.1 mmol/L 2 hours after a 75g oral glucose load. Impaired glucose tolerance
refers to a level of 7.8-11.1 mmol/L 2 hours after a 75g oral glucose load. Some pregnant women will
have pre-existing diabetes. There are other women who have undiagnosed diabetes. Some women
however will develop impaired glucose tolerance during pregnancy (gestational diabetes).
Many units screen for gestational diabetes by offering a 75g oral glucose tolerance test (OGTT) to
high risk women
Maternal BMI >30kg/m2
Family History of diabetes
Previous baby >4.5kg
Previous unexplained stillbirth
Previous congenital anomaly
In Ninewells Hospital all women have a random blood sugar assessed at the booking visit and at 28
weeks gestation. A level of >7.0 mmol/L is an indication for a formal OGTT. Urinalysis for
glycosuria is performed at every antenatal visit. Women are referred for an OGTT as soon as possible
if there is >/= 2+ glcosuria or if 1+ glycosuria is present on 3 occasions.
7
Complications of Pregnancy in Women with Diabetes:
Maternal:
Nephropathy
Retinopathy
Ischaemic Heart Disease
Poor glycaemic control
Pre-eclampsia
Infections
Venous Thromboembolism
Fetal:
Miscarriage
Congenital Anomalies – Cardiac / NTD / Sacral agenesis
Polyhydramnios
Pre-term delivery
Macrosomia – traumatic birth injury
Intra-uterine Death
Neonatal:
Respiratory Distress Syndrome
Hypoglycaemia
Polycythaemia
Jaundice
8
Polyhydramnios is the term used to describe an excess of amnioitic fluid. While the condition might
be suspected clinically, ultrasound is used to confirm the diagnosis. A single vertical pool depth of
more than 8cm or an amniotic fluid index of more than 25cm is diagnostic.
9
Detailed ultrasound scan to identify congenital anomalies
(anencephaly, oesophageal atresia, duodenal atresia, congenital diaphragmatic hernia)
Ultrasound of placenta to exclude chorioangioma
Glucose tolerance test to identify gestational diabetes
If fetal hydrops present :
TORCH and Erythrovirus B19 screen
Blood group and red cell antibodies
Kleihauer test
Consider fetal karyotype if hydrops or major congenital anomaly
10
Abdominal pain and maternal discomfort
Pre-term labour
Unstable lie
Cord / Limb prolapse
Placental abruption
Post partum haemorrhage