I metodi barriera.
Al momento della
eiaculazione, le prime gocce del seme, pių ricche in spermatozoi, entrano in vagina
e in pochi secondi nel muco cervicale. Lė possono risiedervi diversi giorni,
fino a 5 giorni prima dell'ovulazione, in modo tale da essere fecondanti.
I metodi barriera,
ostacolano l'entrata degli spermatozoi nel tratto genitale femminile o l'ascesa
verso il canale cervicale. Si dividono in tecniche maschili e femminili.
Le tecniche maschili
sono il coito interrotto e il
condom.
Le tecniche femminili
sono il diaframma , il cappuccio cervicale, il preservativo femminile. insieme
a spermicidi e spugne vaginali con spermicidi.
Mauck C, Callahan M, Weiner DH,
Dominik R
Contraception
1999 Aug;60(2):7 1-80
Contraceptive Research
and Development Program (CONRAD Program), Eastern Virginia Medical School,
Arlington 22209, USA.
The FemCap is a new
silicone rubber barrier contraceptive shaped like a sailor's hat, with a dome
that covers the cervix, a rim that fits into the fornices, and a brim that
conforms to the vaginal walls around the cervix. It was designed to result in
fewer dislodgments and less pressure on the urethra than the cervical cap and
diaphragm, respectively, and to require less clinician time for fitting. This
was a phase II/III, multicenter, randomized, open-label, parallel group study
of 841 women at risk for pregnancy. A subset of 42 women at one site underwent
colposcopy. Women were randomized to use the FemCap or Ortho All-Flex
contraceptive diaphragm, both with 2% nonoxynol-9 spermicide, for
28 weeks. The objectives were to compare the two devices with regard to their
safety and acceptability and to determine whether the probability of pregnancy
among FemCap users was no worse than that of the diaphragm (meaning not more
than 6 percentage points higher). The 6-month Kaplan-Meier cumulative
unadjusted typical use pregnancy probabilities were 13.5% among FemCap users
and 7.9% among diaphragm users. The adjusted risk of pregnancy among FemCap
users was 1.96 times that among diaphragm users, with an upper 95% confidence
limit of 3.01. Clinical equivalence (noninferiority) of the FemCap compared
with the diaphragm, as defined in this study, would mean that the true risk of
pregnancy among FemCap users was no more than 1.73 times the pregnancy risk of
diaphragm users. Because the observed upper 95% confidence limit (and even the
point estimate) exceeded 1.73, the probability of pregnancy among FemCap users,
compared with that among diaphragm users, did not meet the definition of
clinical equivalence used in this study. The FemCap was believed to be safe and
was associated with significantly fewer urinary tract infections. More women
reported problems with the FemCap with regard to insertion, dislodgement, and
especially removal, although their general assessments were positive. The two
devices were comparable with regard to safety and acceptability, but a 6-point
difference in the true 6-month pregnancy probabilities of the two devices could
not be ruled out. Further studies are needed to determine whether design
modifications can simplify insertion and removal.
Publication Types: Clinical trial ,
Clinical trial, phase ii, Clinical trial, phase iii , Randomized controlled trial