Introduction.Anatomy of Human Uterus.The Intrauterine Devices. Historical Background Estimated extend Of Use Mechanism Of Action Morphological & Biochemical Endometrial Change By IUD Complications
The uterus function mainly as a reproductive organ harboringthe developing embryo and fetus. Rich in blood supply, so potential organ for systemic drugadministration. Intrauterine devices, being easily inserted into uterine cavityfor long periods & having minimal complications, suggested aspossible vehicle for this purpose. To use the uterine cavity for systemic drug delivery, theimportant parameter to be known are uterine anatomy,physiology & histology.
Uterus is hollow, pear shaped fibromuscular organ whoseshape, weight & dimension vary considerably Depending upon both estrogenic stimulation & previous birthor parturition. The function of uterus is to house & nourish the embryo &fetus and birth by applying powerful contraction of its thickmuscular walls In young nulliparous adult it measures 8cm long, 5cm widthand 2.5cm thick, weigth around 30-40g Between birth and puberty the uterus descends graduallyfrom lower abdomen to true pelvis.
• After puberty it located in the midline in true pelvis behindsymphysis pubis & urinary bladder and in front of rectum.• The uterus has 2 portions, an upper muscular corpus & lowerfibrous cervix.• Internal os is a slight constriction corresponding to narrowingof the cavity & part above it is corpus while below it is cervix.• Fundas is nothing but portion of corpus that extends aboveinsertions of fallopian tubes.• In reproductive women, the corpus is considerably larger thanthe cervix, but before menarche, and after menopause, theirsize are similar.
• In coronal section it is triangular, its base being formed by theinternal fundal surface between the openings of the uterinetubes; its apex is the internal os, leading to the cervical canal.
• The intrauterine device is highly effective in preventing thepregnancy.• The first IUD used specifically for contraception was describedby Richter in 1909. It was a ring made of silkworm gut• Graefenberg in 1931 describe that core of silkworm gutencircled by alloy of copper, nickel & zinc highly effective inpreventing pregnancy.• Early devices had local success but general medical opinionprevented their large scale adoption.
• In 1960, the first of the so called “second generation” IUDsrepresented by “Margulies spiral” was introduced.• This device was made of plastic without metal but with bariumsulfate being added to the plastic to render its radio opaque (dense material that prevent electromagnetic passage).• In 1962, Lippes loop, which is still one the most widely usedIUDs. This IUD was the first to have a nylon thread attached to thelowest part of the device; facilate easily removal form uterinecavity.
• Using a T carrier with addition of 200mm2 copper wirereduced the pregnancy rate 18% in women year with plain Tcarrier to 1% women year.• A number of copper bearing devices are now commerciallyincluding the copper-7 & copper-T in various other forms.• Scommegna et al, developed the hormone releasing devicesand showed that it is effective in preventing pregnancy as thecopper-bearing IUD.• The progestasert is a T shaped device, consisting of apermeable polymer membrane which releases progesterone ata predictable, controlled rate of 65 micro g per 24 hr over aperiod of a year.
• Similar devices containing large amounts of progestrone that isreleased at a lower rate, were expected to be effective for 3-5 yrs,but found to be effective life span for 1.5-2yrs• A new hormone releasing device with shape based on that ofthe Nova-T IUD, releasing 20µg/day levonorgestrel from areservoir in the form of polydimethylesiloxane collar ( siliconpolymer) gives a low pregnancy rate i.e. 0.3% at 1 yr, withsignificant reduction in blood loss during menstrual.• Reduction in pain during menstruation but an increasediscontinuation rate on account of amenorrhea (up to 10%) (absence of menstrual cycle in reproductive women ).
• Intrauterine devices (IUDs) prevent fertilization primarily byinterfering with the ability of sperm to survive and to ascend thefallopian tubes, where fertilization occurs.• Having a foreign body in the uterus, such as an IUD, causesboth anatomical and biochemical changes that appear to be toxicto sperm. Studies have generally found that sperm are not asviable among IUD users, compared to other women.•When a foreign body (IUD) is in the uterus, the endometriumreacts by releasing white blood cells, enzymes andprostaglandins; and these reactions of the endometrium appear toprevent sperm from reaching the fallopian tubes.
• In addition, copper-bearing IUDs release copper ions into thefluids of the uterus and the fallopian tubes, enhancing thedebilitating effect on sperm.• Evidence for these mechanisms includes physical examinationof womens eggs. When an ovum is fertilized, it begins to producehuman chorionic gonadotropin (hCG) near the time ofimplantation.• A 1987 study to monitor hCG production in 40 women usingIUDs found only one probable fertilized egg among 107 cycles.• "Whatever the IUDs specific mechanism of action, it appearsthat the IUD effectively interrupts the reproductive process beforeimplantation," the study concluded.
• Half of the women using nocontraception who had intercourseduring the fertile period had ova thatwere consistent in appearance withfertilized eggs.• In contrast, none of the ova takenfrom copper IUD users who hadintercourse appeared to be fertilized.Also, no ova were found in theuterus of any of the copper IUDusers.• "IUDs exert effects that extendbeyond the body of the uterusand interfere with steps of thereproductive process that takeplace before the eggs reach theuterine cavity,"
• The levonorgestrel IUD, called an intrauterine system, usesdifferent mechanisms. Like other progestin methods, this deviceprevents pregnancy primarily by thickening cervical mucus, whichinhibits the ability of sperm to enter the uterus.
• Morphological & biochemical endometrial changes caused byIUD are that whenever a foreign body is introduced into theuterine cavity.• The biochemical & cellular changes reaction take place,characterized by specific changes in endometrial tissue.• Increased vascular permeability, edema, and stromal infiltrationof leukocytes, including neutrophils, mononuclear cells andmacrophages have been seen.• In the normal menstrual cycle, extensive leukocyte infiltrationoccur about 24-48hr prior to the onset of menstruation.
• It should be emphasized that the foreign body reaction seenwith both medicated and non medicated IUDs occurs in theabsence of bacterial infection & especially in the area adjacent tothe device.• The foreign body reaction should not be confused with theendometritis, which is a bacterial inflammatory condition.• The high levels of intrauterine protein reported in IUD usersmight reflect the cellular degradation of these neutrophils ¯ophages and thereby further contribute to anti fertility effect.• The foreign body reaction caused by non medicated devices areenhanced by addition of copper to the IUD.
• Insertion of the IUD may introduce bacteria into the uterus. Theinsertion process carries an increased risk of pelvic inflammatorydisease in the first 20 days following insertion.• It is very important that the provider use proper infection-prevention techniques during insertion.• Some barrier contraceptives protect against STDs. Hormonalcontraceptives reduce the risk of developing pelvic inflammatorydisease (PID), a serious complication of certain STDs. IUDs, bycontrast, do not protect against STDs or PID.• During the placement appointment, the cervix is dilated in orderto sound (measure) the uterus and insert the IUD. Cervix dilationcan be uncomfortable and, for some women, painful.
• Taking NSAIDS before the procedure can reduce discomfort, ascan the use of a local anaesthetic. Misoprostol 6 to 12 hrs beforeinsertion can help with cervical dilatation.• After IUD insertion, menstrual periods are often heavier, morepainful, or both - especially for the first few months after they areinserted. On average, menstrual blood loss increases by 20–50%after insertion of a copper-T IUD; increased menstrual discomfortis the most common medical reason for IUD removal.• The string(s) may be felt by some men during intercourse. If thisis problematic, the provider may cut the strings even down to thecervix, so they cannot be felt. Shortening the strings does preventthe woman from checking for expulsion• Non-hormonal (copper) IUDs are considered safe to use whilebreastfeeding.