DISCREPANCY IN UTERINE SIZE

An understanding of the issues involved when a uterus doesn’t correspond to its gestational age

By Associate Professor Dr

Hanifullah Khan

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To understand the definitions involved

To understand the implications of this

situation

The important points to consider

Objectives

Discrepancy – what is it?When the uterine size does not correspond to the expected gestation

May be larger or smaller

Objective measurement - > 2 cm variation with symphysiofundal height (SFH)

Implications of this situation

Has there been a

mistake in calculating gestation?

Is there an underlying problem

causing this discrepancy?

Is there a problem with the mother?

Is the fetus at risk?• If so, when do

we deliver it?

Points to consider

The patient has been found to have a gestation which does not correspond to calculations.

This may be a feature of an underlying problem

The problem may be related to the mother, fetus or placenta

It is our job to determine the underlying cause of this problem

Dates

Be absolutely positiveThe mother remembers the exact LMP (1st day)

The periods have been regular

The onset of pregnancy symptoms & quickening correspond to the dates

That an early pregnancy ultrasound (if done), confirmed the dates

Subsequent antenatal check ups have noted previous corresponding growth of uterus

In all cases, always begin by confirming the dates

Remember, an early pregnancy ultrasound scan is the definitive

decider of dates

IUGR

Intrauterine growth restriction or Fetal growth restriction

Leads to uterus < dates A manifestation of underlying problem Maternal, fetal or placental Most commonly caused by placental insufficiency

(unknown cause), hypertensive disease, maternal disease, fetal anomaly

Most non-fetal causes lead to asymmetrical FGR (the so-called head-sparing effect)

Fetal Growth RestrictionLeads to long term problems

The left ear

Big baby• If fetal macrosomia

is the cause in an uterus > dates, it is most often a consequence of gestational diabetes

• GDM can also lead to polyhydramnios on its own

• It is mandatory to look hard for GDM in such cases

Macrosomia

Fetal anomalies

Any discrepancy in uterine size must lead to an extensive search for fetal anomalies

Multiples

Any large uterus may be caused by more than one passenger in it

See for yourself

The diagnosis of SGA

A constitutionally small fetus is a diagnosis of exclusion This is the last diagnosis in your list of differentials

Always rule out disease before you can say its normal

These fetuses display linear growth despite being small

Usually, the mother is also small (this is logical)

Summary

Discrepancy in uterine size

This denotes a uterine size not corresponding to gestational age

It may be a sign of an underlying problem

This problem could be of maternal, fetal or placental origin

One common cause is wrong dates

Rule out disease before diagnosing a constitutionally small fetus

THE END Thank You Very Much