Turner Syndrome
One of the most common chromosomal abnormalities in women, TS occurs in
1 in 2500 live female births and is characterised complete or partial
absence of the X chromosome32. Of these, up to 50%
are expected to have cardiovascular malformations in addition to the
common features of short stature and primary ovarian
insufficiency33. Only 5 – 6% will have a spontaneous
pregnancy34. For women with TS, oocyte donations have
presented the opportunity for the majority to carry a pregnancy, but
there is some debate whether the risk is too
high34,35. Although TS itself is an increased relative
risk of AD, estimated maternal mortality rates of 2% in TS from AD or
rupture34. A study by Bernard et al. regarding
outcomes in 480 patients found 5.6% had spontaneous pregnancies; none
of these were associated with aortic root dilatation or aortic
dissection36. Evidence shows that different karyotypes
in TS may offer different risks; in Bernard’s study, mosaic karyotype
predisposed to spontaneous pregnancy, milder phenotype and therefore may
have a lower risk to other karyotypes34,36. The
recommendations from the 2016 Cincinnati International TS meeting
suggested that full imaging, exercise testing and TTE should be
performed 2 years prior to planned pregnancy or assisted reproductive
therapy37. Any female with a prior history of AD
should be advised against pregnancy, or if already pregnant, to be
monitored closely and deliver by Caesarean. If there is no evidence of
dilatation, TTE should be carried out at least once; suggested around 20
weeks, but if there is any evidence of dilatation, hypertension, BAV or
other risk factors, monitored at least 1 to 2 monthly up to 6 months
postpartum37. Using aortic size index (ASI)—
absolute aortic diameter in cm divided by body surface area, which
better predicts AD risk for TS— vaginal delivery is feasible at ASI
less than 2cm. Above 2cm and less than 2.5cm, Caesarean should be
considered, but above 2.5cm Caesarean is
recommended37.