The operation is of help in the differential diagnosis of low abdominal and pelvic pain, particularly in detecting the unruptured ectopic pregnancy. Laparoscopy is also used in fertility investigations to check the patency and freedom of the fallopian tubes, while the ovaries can be examined for follicles and the presence of corpora lutea indicating ovulation. With the operating laparoscope, or through a separate portal of entry and guided by a single-channel instrument, therapeutic pro- cedures may be performed. The most common of these is sterilisation, when a loop of each fallopian tube is occluded by either cautery, a Silastic band, or a clip. Through the laparo- scope small foreign bodies (such as misplaced intrauterine devices) may be retrieved and localised patches of endometriosis can be fulgurised. A less common use which has attracted attention recently is the harvesting of eggs from almost ripe follicles; these can then undergo extracorporeal fertilisation for reinsertion later into the woman’s uterus.