We compare the results of subzonal insemination (SUZI) and intracytopl
asmic sperm injection (ICSI) carried out between February 1993 and end
of August 1994. A total of 232 couples underwent 302 cycles of micro-
assisted fertilization (79 patients had SUZI for a total of 93 cycles,
153 patients ICSI for a total of 209 cycles). The indications for tre
atment were obstructive azoospermia in 35 cycles, ejaculatory failure
with severely low sperm count in 7 cycles, and failure of fertilizatio
n in a previous IVF cycle or less than 10% of oocytes fertilized in 87
cycles. In 173 cycles the indication for treatment was a poor semen p
arameter. Patients undergoing ICSI had significantly higher fertilizat
ion rates [43 (728/1692) versus 22.3% (151/676), chi(2) = 86.308, P <
0.0001], better chances of embryo transfer [95 (199/209) versus 73% (6
8/93), chi(2) = 30.671, P < 0.001], and greater numbers of embryos tra
nsferred (2.4 +/- 0.9 versus 1.6 +/- 1.2 F = 42, P < 0.0001) than pati
ents who had SUZI. Eighteen patients became pregnant following the SUZ
I procedure, a pregnancy rate of 19% per egg collection, compared with
28% for those who underwent the ICSI procedure, where 58 out of 209 b
ecame pregnant. The pregnancy rate was similar in those who underwent
embryo transfer, whether they had ICSI or SUZI (29.2 and 28.6% respect
ively). Overall, the pregnancy rate doubled with each number of embryo
s transferred, so it was 8.9% when one embryo was transferred, which i
ncreased to 18.3% when two embryos were transferred, and this rose to
37.7% when three embryos were transferred. There was no significant di
fference in the pregnancy wastage rate between SUZI and ICSI. None of
the offspring from either SUZI or ICSI showed any evidence of fetal ab
normalities. Pregnancy rate was negatively correlated, with sperm prog
ression being 36% (36/100) if progression was <2 and 19.8% (40/202) if
it was greater than or equal to 2 (chi(2) = 8.99, p < 0.002). ICSI th
erefore provides a higher number of embryos available for transfer and
should be the primary treatment for severe male factor infertility.