The 11-14 weeks scan - KH Nicolaides, NJ Sebire, RJM Snijders, AP Souka

Chapter 1

WOMENS’ ATTITUDES TO FIRST VERSUS SECOND TRIMESTER SCREENING

Studies investigating the preference of pregnant women in terms of the methods of screening, have reported that the vast majority prefer this to be carried out in the first rather than in the second trimester. A criticism of NT screening has been that some women with increased fetal NT will face unnecessary decisions regarding invasive testing and ultimately pregnancy termination in an affected pregnancy that would otherwise have ended in spontaneous miscarriage. In a survey of women’s preferences, about 70% stated that they would still choose NT screening even if all the Down’s syndrome pregnancies identified by this method miscarried before the second trimester (Mulvey and Wallace 2000). The women wanted to know if their fetus had had Down’s syndrome regardless of the pregnancy outcome and they also valued the knowledge of an underlying reason for a miscarriage if it occurred.

Clinical Importance of respect for autonomy

Respect for autonomy is a central principle in medical ethics and law. This ethical principle obliges the physician to elicit and implement the patient’s preferences. The relevance of respect for autonomy to first trimester screening is two-fold. Firstly, early diagnosis of fetal abnormality and the option of early termination of pregnancy are important to many women. Secondly, most first trimester screening tests provide reassurance for many women who would prefer not to have an invasive procedure if the risk is low. Consequently, the provision of a high-quality first trimester screening service significantly enhances the autonomy of pregnant women (Chasen et al 2001).

Women’s choice

• The vast majority of pregnant women prefer screening and prenatal diagnosis to be performed in the first, rather than in the second trimester.