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Table 2 Kaplan-Meier estimates of the probabilities of vasectomy success (N = 389). Probabilities of success by follow up week and age (< 35 or ≥ 35 years) for success defined as oligozoospermia and azoospermia.

From: Effectiveness of vasectomy using cautery

  Probability of success defined as oligozoospermia1 (95% CI) Probability of success defined as azoospermia2 (95% CI)
Follow-up week All participants Age < 35 years Age ≥ 35 years All participants Age < 35 years Age ≥ 35 years
2 44.9% (39.9, 49.8) 48.7% (40.8, 56.6) 42.3% (36.0,48.7) 25.8% (21.4, 30.1) 22.7% (16.1, 29.3) 27.8% (22.0, 33.5)
5 74.5% (70.1, 78.9) 77.9% (71.4, 84.5) 72.2% (66.5, 78.0) 58.2% (53.3, 63.1) 61.0% (53.3, 68.7) 56.3% (49.9, 62.7)
8 87.7% (84.3, 91.0) 90.0% (85.1, 95.0) 86.1% (81.7, 90.6) 73.6% (69.2, 78.1) 77.6% (70.8, 84.3) 71.0% (65.1, 76.9)
12 94.9% (92.7, 97.1) 97.2% (94.7, 99.6) 93.5% (90.3, 96.7) 85.3% (81.8, 88.9) 91.8% (87.4, 96.3) 81.1% (76.0, 86.2)
16 97.1% (95.3, 98.8) 97.9% (95.5, 100.0) 96.5% (94.2, 98.9) 90.2% (87.2, 93.3) 93.9% (90.0, 97.8) 87.9% (83.6, 96.3)
20 98.4% (97.0, 99.8) 99.3% (97.9, 100.0) 97.8% (95.7, 99.9) 94.0% (91.6, 96.5) 95.9% (92.7, 99.1) 92.8% (89.3, 96.3)
24 98.4% (95.3, 100.0) 99.3% (97.9, 100.0) 97.8% (93.6, 100.0) 98.0% (95.3, 100.0) 98.2% (94.7, 100.0) 98.1% (94.5, 100.0)
  1. 1less than 100,000 sperm/mL in two consecutive specimens at least two weeks apart with all subsequent samples showing only rare sperm. 2two consecutive specimens with no sperm at least two weeks apart with all subsequent samples showing only rare sperm