Methods	Randomisation by telephone.
Participants	Women aged between 19 and 48 years attending for first trimester fetal diagnosis of genetic diseases. Indications for fetal diagnosis included chromosomal aberration, sex determination for X linked diseases, metabolic diseases, DNA analysis for haemoglobinopathies and haemophilias. Gestational age between 8 and 12 weeks. Exclusion criteria: multiple pregnancy, vaginal infection, pending cerclage, vaginal bleeding and placenta inaccessible either via cervical canal or via abdominal wall
Interventions	TC and TA CVS were performed using a 20 G needle and no more than 2 cannula or needle insertions used in 1 session
Outcomes	Technical difficulty and quantity of tissue obtained along with pregnancy outcome
Notes
Risk of bias
Item	Authors’ judgement	Description
Allocation concealment?	Yes	A - Adequate