This was an unrecognised cornual ectopic pregnancy in a non communicating rudimentary horn of a unicornuate uterus. Patient presented acutely with rupture and FDIU at 20 weeks gestation.

The diagnsosis was made definitively at surgery. Placenta was known to be left in situ, for methotrexate therapy and bHCG tracking. 

Subsequent ultrasound demonstrates the right unicornuate uterus communicating with a single cervix. and the non-communicating left rudimentary horn containing hemorrhage and retained products of conception. 

There were no associated renal tract anomaly, however this should be sought routinely with any Mullerian duct anomaly due to the frequent association.