1. When the uterus is large or small for dates....
Max Brinsmead MB BS PhD
May 2015

2. When the uterus is LFD or SFD you first need to know…
What is normal
SFH = Weeks of gestation is valid only between 20 and 30 weeks
Thereafter the mean runs off to 37 cm at 40 weeks
This should be validated in each population
And the 95% confidence limits are not less than +/- 3 cm

4. When the uterus is LFD or SFD you also need to know DATES accurately…
Menstrual history is unreliable when…
The patient is uncertain
She has a good reason to tell lies
Cycles are irregular
Ovulation was delayed >14 days by
Miscarriage
Breast feeding
Hormonal contraception
Quickening is unreliable when…
The placenta is on the anterior uterine wall
The patient is obese
There is something wrong with the fetus or fluid
Ultrasound is unreliable when…
It is done by a non expert or with poor equipment
It is done late in pregnancy
There is something wrong with the fetus e.g. microcephaly

5. If the uterus is LFD think of…
Wrong dates
Hydatidiform mole
Multiple pregnancy
Many small parts
Three poles
Lots of fluid and difficult to feel the baby
Polyhydramnios
Uterus lifted up by
Previous CS
Tumours e.g. Fibroids, Ovarian cyst
A Large Baby

6. If the uterus is LFD then…
Ultrasound is useful because it readily diagnoses:
Hydatidiform mole
Multiple pregnancy
Polyhydramnios
Fibroids and tumours
But ultrasound is poor at:
Diagnosing fetal abnormalities
Estimating fetal weight
If there is a large baby:
Check for maternal diabetes
But macrosomia more commonly due to maternal obesity
+/- Excessive weight gain in pregnancy

7. If there is fetal macrosomia then…
There is a risk of intrauterine death
If the mother is diabetic
And it is poorly controlled
There may be birth difficulties
Cephalopelvic disproportion
Shoulder dystocia
Maternal birth injury and PPH
Vaginal breech birth may not be wise
There may be neonatal problems
From hypoglycaemia
From birth injuries

8. Management of suspected fetal macrosomia…
Exclude maternal diabetes or…
Control maternal blood sugars before and during birth if diabetic
Refer to a place where expert assistance is available
Consider induction of labour but only when it is safe to do so
Watch progress in labour and prepare for complications
Have someone expert standby for the delivery

9. If the uterus is SFD think of…
Wrong dates
Oligohydramnios
Premature rupture of membranes
Abnormality of the fetal renal tract
Intrauterine growth retardation (IUGR)
Intra uterine growth retardation
There are two major categories
Symmetrical = head, trunk and body reduced proportionaely
Asymmetrical = head-sparing growth restriction

10. Causes of Symmetrical IUGR
Constitutional smallness
Consider maternal size
Ethnic origin
Paternal influence less important
Fetal Infections
TORCH = Toxoplasmosis, Other, Rubella, Cytomegalovirus and Herpes
Remember Syphilis and HIV
Fetal Abnormalities
Especially chromosomal abnormalities such as Trisomy 21, 13&16

11. Causes of Asymmetrical IUGR
Anything that reduces Maternal-Uterine-Placental to Fetus transfer of oxygen and nutrients
Maternal smoking and malnutrition
Severe maternal anaemia
Chronic maternal disease
Maternal hypertension especially pre eclampsia
Uterine malformations
Some placental diseases
Maternal thrombophilias congenital or acquired
Recurrent antepartum haemorrhage
An idiopathic group

12. A SFD uterus is more serious when…
The mother was underweight to begin with
She has not gained weight appropriately
There is a past history of IUGR or pregnancy loss
A condition known to be associated with IUGR is also diagnosed
Pre eclampsia
Recurrent APH
Chronic maternal disease or anaemia

13. Management of the SFD baby
Accurate diagnosis
Is the baby salvageable?
Mother at risk?
Steps that improve M-U-P-Fetal transfer of oxygen and nutrients
Stop maternal smoking
Bed rest
Correct anaemia
Monitor fetal growth and well being
There is little point in ultrasound at less than 2w intervals
Timely delivery
Must weigh up the risks of induced delivery against the risk of remaining in utero

14. Any Questions or Comments?
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Any Questions or Comments?