Fatherhood without apparent spermatozoa after vasectomy

Lancet. 1994 Jul 2;344(8914):30. doi: 10.1016/s0140-6736(94)91052-9.


Fatherhood after vasectomy is rare. We describe 6 cases of DNA-proven fatherhood after vasectomy in association with persistently negative semen examination. All vasectomy patients and their partners should be counselled about the small possibility of late failure, and warning of failure should be recorded.

PIP: This short report describes 6 cases of vasectomized fathers who have negative semen analyses. The cases occurred between 1984 and 1991. Paternity was proven by deoxyribonucleic acid (DNA) analyses of blood samples taken from father and child. All children were normal. All the men had had 2 consecutive negative semen analyses after vasectomy. They continued to have negative samples after pregnancy occurred; 1 man had 8 such tests. The men must have been producing sperm intermittently. At Churchill Hospital, Oxford, semen from 1000 men, who had had two consecutive negative tests the year before, was examined. 6 (0.6%) samples were positive, although none of these cases were associated with pregnancy. The sperm counts were less than 10,000/ml and repeat testing a month later showed negative results. Since the possibility of late failure of vasectomy is at least 1 in 2000 and this failure is a common cause of legal action, clients should receive a warning that is on record.

MeSH terms

  • Female
  • Humans
  • Male
  • Pregnancy*
  • Sperm Count*
  • Vasectomy*