AFJOG

GUIDELINES INTRODUCTION Screening for Down syndrome and other common autosomal trisomies has been a part of obstetric care for half a century. 1 The development of ultrasound, biochemistry and genetic technology has complicated matters, so that patients and professionals are indeed “spoilt for choice.” 2 Various options to screen for trisomies include different combinations of biochemistry and ultrasound in the first and second trimester as well as non-invasive prenatal testing (NIPT) of cell-free fetal and placental DNA in the maternal circulation. Despite access to the different screening tools, 3 a recent survey has shown that still only one in three cases of trisomy 21 is diagnosed prenatally in private practice in South Africa. 4 The same survey has confirmed that the different screening tests performed as well as would be expected from published literature. While it is possible that many patients opt against screening for trisomies, it is also possible that professionals do not offer screening to all pregnant women. Indeed, a number of medicolegal claims for missed diagnosis of Down syndrome relate to patients not having been offered screening or testing for Down syndrome. 5 Many of the options are too expensive or otherwise inaccessible to the average patient. The myriad of possibilities can make it more difficult to effectively counsel patients and for patients to make a well-informed choice. To simplify matters for the practicing obstetrician and to improve equitable prenatal care and counselling, we present these guidelines as a practical guide to guide screening for chromosomal and structural fetal anomalies in pregnancy. These guidelines should also help to guide the practitioner towards ethical and medicolegally safe practice. GUIDELINES 1. Offer all patients screening for common autosomal trisomies (trisomy 21, 18 and 13) as appropriate to gestational age. The possibility of screening should be discussed with all patients who present in the first half of pregnancy, regardless of the patient’s age, socio-economic or religious background. The practitioner should inform patients that high risk results on screening tests would require further diagnostic tests before any further intervention is undertaken. Interventions might include pregnancy termination, but might also include fetal therapy, optimizing conditions for neonatal care at delivery, as well as parental preparation for possible future special needs. The patients should also know that they may change their minds at any point, but must be aware that some options are time sensitive and that screening and intervention options become more limited later in pregnancy. 6 They should also be aware that no screening test can completely rule out an anomaly. If the patient opts against screening for common autosomal trisomies: 2. Make clinical notes of her decision, as well as her reason for the decision and whether her partner was present. Include the patient’s understanding and acceptance of the possible implications of her choice in writing. Give the patient material to access at home (such as the SASOG document on prenatal screening, which can be downloaded in several languages at https://www.sasuog.org.za/prenatal-tests-1 ). Medicolegally, the safest course of action might be to have the patient sign a document that she decided not to avail herself of screening. Retain all documentation and keep it accessible for future reference. 3. Offer a basic scan to all patients who opt against screening for trisomies An ultrasound e.xamination should be offered to all pregnant women to assess fetal cardiac activity; the number of fetuses (and in case of a multiple pregnancy, the chorionicity and amnionicity), the gestational age or fetal size, basic fetal anatomy, amniotic fluid volume and placental location and appearance. 7 The patient should be aware that while some abnormalities may be detected on a basic scan, this is not its primary purpose and the majority of genetic or structural abnormalities would not be detected. Abnormal findings and appropriate referral should be documented and discussed with the patient. If the patient opts for screening for common autosomal trisomies: 4. Perform a basic scan. See paragraph 3 for the contents of the basic scan. L Pistorius 1 , C Cluver 2 , I Bhorat 3 , C Hall 4 , L Smit 5 , C Scott 1 , M Hoffman 6 , B Goolab 7 , J du Buisson 8 , J Trusler 9 and L Geerts 2 1 Mediclic Panorama, Cape Town, South Africa 2 Department of Obstetrics and Gynaecology, Faculty of medicine and health sciences, Stellenbosch University, Tygerberg Hospital, Stellenbosch, Cape Town, South Africa 3 Department of Obstetrics and Gynaecology, Nelson R Mandela School of Medicine, University of KwaZulu Natal, South Africa 4 Head of Legal, Natmed Medical Defence 5 Department of Medical Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg Hospital, Stellenbosch, Cape Town, South Africa 6 Chemical Pathology, PathCare Laboratories, South Africa 7 Lenmed Ahmed Kathrada Private Hospital, Lenasia , Johannesburg, South Africa 8 CEO: Gynaecology Management Group, Mediclinic Panorama, Cape Town, South Africa 9 Clinical Pathology and pathologists special biochemistry (Ampath Laboratories), South Africa Screening for chromosomal and structural fetal anomalies: guidelines for South African private practice African Journal of Obstetrics and Gynaecology | Volume 1 | Issue 2 | 2023 | 25