A 37-year-old Chinese female, G2P1, presents with a uterus smaller than dates at 32 weeks’ amenorrhoea. Discuss how you would investigate and manage this case.

There are various causes of a uterus smaller than dates. A detailed history is warranted to derive the possible differential diagnoses followed by a physical examination and relevant investigations to determine the exact aetiology.

The following are possible causes for a uterus smaller than dates:

1.	Wrong dates.
2.	Intrauterine growth retardation.
3.	Intrauterine death.
4.	Constitutionally small baby.
5.	Transverse lie.
6.	Congenital abnormalities.

As wrong dates is a common cause, I would first like to ask the following questions to exclude wrong dates:

1.	How sure is the patient of her LMP? Did she keep any record?
2.	Was the LMP regular and normal, or was it only spotting?
3.	Regularity and duration of menstruation.
4.	History of amenorrhoea / oligomenorrhoea
5.	When was her last pregnancy?
6.	When did she stop lactating?
7.	Was she on oral contraceptive and if she is, when did she stop?
8.	When and how was the pregnancy diagnosed and was any vaginal examination or ultrasound done? 
9.	Time of spotting, morning sickness and quickening during pregnancy. 

Clues to suggest wrong dates:

1.	Unsure of LMP.
2.	Irregular cycles.
3.	On OC / lactation, closeness to previous pregnancy.
4.	Changing LMP at subsequent visits.
5.	Spotting during early pregnancy.
6.	Late booking.
7.	Low parental IQ.

To exclude IUGR / IUD:

1.	Any static weight or decreased fetal movement?
2.	Possibility of an intrauterine infection: rubella vaccination, fever, rash, discharge and STD history.
3.	Possibility of congenital abnormalities in this patient who is older than 35 years old: past and maternal history.
4.	Exposure to teratogens during pregnancy: drugs, irradiation, alcohol, smoking.
5.	Multiple pregnancy.
6.	Maternal diseases: Diabetes, hypertension, heart and renal disease.
7.	Possibility of an abruptio placenta: bleeding PV, abdominal pain.
8.	Blood group of both parents to exclude ABO incompatibility.
9.	Birth weights of previous pregnancies: fetus may just be constitutionally small. 

Find out from case notes:

1.	Any ultrasound done in early pregnancy.
2.	How was the antenatal progess so far: symphysial-fundal height, weight gain.
3.	Any complications: proteinuria, diabetes mellitus and hypertension.

Physical examination:

1.	General:
-	Stature: weight, height and nutritional state: if patient is malnourished, it can lead to IUGR which explains the smaller uterus than dates.
-	Blood pressure.
-	Genitalia: vesicles, ulcers and discharge.
-	Fundus: toxoplasmosis, hypertension and diabetes mellitus.

2.	Abdomen:
-	Confirm that uterus is less than dates by measuring the SFH.
-	Assessing fetal movements: whether there are any and their degree.
-	Fetal size, lie and attitude.
-	liquor volume.
-	Fetal heart: none is detected in an intrauterine death.
-	Exclude laxed abdomen and transverse lie.

Investigations:

1.	CTG:
-	No fetal heart activities: IUD.
-	Non-reactive: IUGR.

2.	Ultrasound:
-	No fetal heart beat: IUD.
-	Decreased reactivity: IUGR.
-	determine symmetrical or asymmetrical IUGR by measuring the head circumference – abdominal circumference ratio.

3.	Other investigations relevant to the underlying cause:
-	Pre-eclampsia: urine dipstick for proteinuria, UFEME, 24 hours UTP, urea & electrolytes, FBC.
-	IUI: serology for TORCH.
-	Blood group of both parents.
-	IUD: coagulation profile

Management

The management plan is tailored according to the diagnosis reached – the cause of the uterus smaller than dates. If it is due to wrong dates, the exact dates can be obtained by doing another ultrasound. If there is an intrauterine death, wait for spontaneous labor in 4 weeks’ time. If a symmetrical IUGR is detected, await for spontaneous abortion of the fetus. If it is asymmetrical, the underlying causes should be rectified wherever possible, e.g. maternal malnutrition, pregnancy-induced hypertension leading to placental insufficiency.