[Retracted] Study on the Effect of B-Ultrasound NT Scan in Early Pregnancy Combined with Serum Screening in Early and Middle Pregnancy for Down Syndrome

Table 1

Coincidence of DS detected by different methods with clinical diagnosis.

Detection method	DS gold standard			Detection method	DS gold standard
	Positive	Negative	Total		Positive	Negative	Total
Ultrasound				Serology
Positive	5	18	23	Positive	4	16	20
Negative	1	144	145	Negative	2	146	148
Total	6	162	168	Total	6	162	168