A birth control method which is highly effective but with very poor reversibility is

Surgical methods like vasectomy and tubal ligation (tubectomy) are highly effective forms of birth control, but they are typically considered permanent or have poor reversibility.

• Vasectomy: In a vasectomy, the vas deferens (the tubes that carry sperm from the testicles) are cut or blocked to prevent the release of sperm during ejaculation. While vasectomy can be technically reversed through a surgical procedure called a vasectomy reversal (vasovasostomy), the success of reversal is not guaranteed, and the chances of achieving pregnancy after reversal may vary. Therefore, it's often considered a permanent method of birth control.
• Tubal Ligation (Tubectomy): Tubal ligation is a surgical procedure in which a woman's fallopian tubes are cut, blocked, or sealed to prevent eggs from reaching the uterus and sperm from reaching the egg. While there are procedures to attempt to reverse tubal ligation, such as tubal reanastomosis, the success rates can vary, and there are no guarantees of restoring fertility. Therefore, like vasectomy, it's generally considered a permanent method.