Table 2 The baseline characteristics of VC groups with different blood flow patterns of the left spermatic vein

Number

68

35

46

16

–

Age (years)

31.1 ± 4.0 (21–41)

32.0 ± 5.4 (18–44)

33.0 ± 6.4 (24–57)

31.6 ± 5.1 (22–41)

0.293

BMI (kg/m²)

26.0 ± 3.3 (18.3–32.3)

25.7 ± 4.1 (18.5–36.1)

25.3 ± 3.7 (18.3–32.2)

24.2 ± 3.5 (19.9–32.2)

0.265

Gray-scale ultrasound parameters

 Left MVD (mm)

2.8 ± 0.6 (2.3–5.4)

2.9 ± 0.5 (2.3–4.7)

2.9 ± 0.6 (2.0–4.8)

2.9 ± 0.5 (2.4–4.3)

0.737

 Right MVD (mm)

1.4 ± 0.4 (0.7–2.2)

1.5 ± 0.4 (0.9–2.2)

1.4 ± 0.3 (0.8–2.2)

1.6 ± 0.4 (1.0–2.2)

0.129

 Left TV (mL)

14.0 ± 4.3 (8.2–29.0)

13.5 ± 3.9 (8.3–22.2)

13.1 ± 3.7 (8.2–23.6)

15.4 ± 3.9 (9.1–23.2)

0.250

 Right TV (mL)

15.5 ± 4.6 (8.1–29.9)

14.4 ± 3.9 (8.2–22.0)

14.7 ± 4.1 (8.0–24.6)

16.7 ± 4.0 (12.7–25.0)

0.261

Reproductive hormone level

 FSH (mIU/mL)

5.1 ± 2.9 (1.6–17.1)

4.6 ± 1.9 (1.5–9.3)

4.7 ± 2.4 (1.3–13.2)

4.4 ± 1.7 (1.8–7.7)

0.661

 LH (mIU/mL)

4.5 ± 2.0 (1.3–9.9)

4.2 ± 1.8 (2.3–10.5)

4.4 ± 1.6 (1.9–8.1)

4.0 ± 1.4 (2.1–7.2)

0.755

 T (ng/mL)

5.1 ± 2.6 (1.6–14.3)

5.2 ± 2.6 (1.4–12.3)

5.3 ± 2.6 (2.0–14.6)

4.9 ± 2.5 (1.2–11.0)

0.919

 PRL (ng/mL)

12.5 ± 11.1 (2.1–75.8)

13.4 ± 10.0 (2.8–43.6)

9.6 ± 5.8 (2.1–27.2)

11.9 ± 6.0 (2.9–25.6)

0.271

 E2 (Pmol/L)

133.8 ± 76.1 (34.7–321.5)

143.8 ± 78.7 (44.6–371.6)

156.6 ± 86.2 (48.6–384.7)

115.0 ± 70.3 (48.2–248.3)

0.253

Semen parameters

 Volume (mL)

2.7 ± 1.1 (1.1–7.0)

2.5 ± 0.9 (0.8–4.2)

2.9 ± 1.4 (0.2–7.0)

2.7 ± 0.9 (1.3–4.4)

0.492

 Concentration (10⁶/mL)

72.6 ± 45.6 (10.0–216.0)

67.1 ± 48.8 (8.0–209.1)

57.2 ± 44.8 (7.0–213.5)

67.0 ± 40.4 (9.0–149.8)

0.377

 Total sperm counts (10⁶)

190.7 ± 131.1 (15.4–642.3)

170.4 ± 147.5 (20.0–748.4)

165.1 ± 158.0 (10.8–566.4)

201.3 ± 152.9 (11.7–485.8)

0.714

 Progressive motility (%)

48.8 ± 12.0 (20.0–74.5)

45.2 ± 14.7 (15.0–75.1)

33.1 ± 16.1 (11.0–65.3)

31.8 ± 14.2 (13.0–61.3)

 < 0.001

 Normal morphology (%)

7.6 ± 4.0 (3.0–25.0)

7.9 ± 4.8 (2.0–21.0)

5.7 ± 3.8 (1.0–18.0)

6.2 ± 4.5 (2.0–20.0)

0.059

 DFI (%)^a

18.7 ± 12.0 (2.6–48.1)

20.4 ± 15.3 (2.2–67.0)

23.8 ± 13.4 (3.4–52.6)

20.7 ± 7.8 (5.7–40.9)

0.288