SBA — Single Best Answer · Review
Question 19
Feto-maternal medicine → Perinatology
Classification
Question
SSBAQuestion Header
Early amniocentesis
Question Stem
A woman requiring invasive prenatal diagnosis asks to undergo amniocentesis at 13+4 weeks rather than waiting until 15 weeks. Which complication is particularly associated with performing amniocentesis before 15+0 weeks?
Options
A
Talipes
B
Congenital diaphragmatic hernia
C
Neural tube defect
D
Fetal hydrops
E
Macrosomia
Explanation
Amniocentesis should not be performed before 15+0 weeks of gestation. Early amniocentesis is associated with a higher risk of pregnancy loss and an increased incidence of talipes compared with later amniocentesis. It is also associated with greater technical difficulty, including more frequent multiple needle insertions and problems with culture. When invasive prenatal diagnosis is required before 15 weeks, chorionic villus sampling is therefore generally the appropriate diagnostic procedure, provided its own gestational timing requirements are met.
Option Validity
B) Congenital diaphragmatic hernia is not the characteristic complication associated with early amniocentesis.
C) Neural tube defects are not described as a consequence of performing amniocentesis before 15 weeks.
D) Fetal hydrops is not the characteristic procedure-related complication of early amniocentesis.
E) Macrosomia is unrelated to the timing of amniocentesis.
Further Reading
Navaratnam K, Alfirevic Z; Royal College of Obstetricians and Gynaecologists. Amniocentesis and chorionic villus sampling: Green-top Guideline No. 8. BJOG. 2022;129:e1-e15. Farrell SA et al. The Canadian Early and Mid-trimester Amniocentesis Trial. J Med Genet. 1999.