Benefits, side effects & risks

Benefits

Due its effects on the endometrium, 52mg LNG-IUS is licenced for endometrial protection in women taking estrogen replacement therapy for 4 years (FSRH supports 5 years, out of licence for HRT add back), and as an effective treatment option in heavy menstrual bleeding.  The lower dosed LNG-IUS are not licenced for the treatment of menorrhagia or endometrial protection though they may have some effect.

52mg LNG-IUS may also have a protective role against endometrial cancer and cervical cancer.  There may be some protection against endometrial and ovarian cancer with the Cu-IUD.

Risks

Studies have shown no significant differences in BMD with women using IUC and controls.

While data is limited, there is no evidence to suggest LNG-IUS use increases the risk of VTE or MI.  However, for women who develop thromboembolic disease while using LNG-IUS, UKMEC recommend risks outweigh the benefits (in keeping with other POC).  For women with either multiple risk factors for cardiovascular disease, stroke, current or history of ischaemic heart disease, or a history or current VTE there is no restriction for the use of the Cu-IUD.

There is limited research into the safety of LNG-IUS and the risk of breast cancer.  There is a weak suggestion that it may have an adverse effect and for that reason UKMEC have advised it an unacceptable choice for women with current breast cancer (UKMEC4) and risks outweighing benefits for those women with a history of breast cancer (UKMEC3), irrespective of receptor status.

LNG-IUS is associated with an increase incidence in ovarian cysts though these are benign and often resolve spontaneously.  This appears to be dose dependent and is more frequent with 52mg rather than the 19.5 and 13mg LNG-IUS.  IUC has not been associated with an increased risk of ovarian cancer. 

Whilst the absolute risk of ectopic pregnancy is low with IUC, if a pregnancy does occur, there is a greater tendency for it to be ectopic (up to 50% in some studies).  Any positive pregnancy test during IUC use requires an urgent pelvic ultrasound to exclude ectopic and clarify IUC position. 

IUC has been linked to an increase in PID, though some studies suggest similar rates of PID to other forms of contraception.  It remains important to screen the women at higher risk before coil insertion.   Chronic pelvic pain is much more common though, and approximately a third of women cite this as the reason for wanting early removal. 

Expulsion: it is estimated 1 in 20 will fall out, usually in the first 3 months.

Although the insertion procedure does carry a risk of perforation, incidence remains small (estimated to be 2 in 1000). 

Current data suggests return to fertility after IUC is similar to methods.

Side effects

Altered menstrual bleeding pattern is common in both LNG-IUS and Cu-IUD.  Whereas more women on 52mgLNG-IUS will experience amenorrhoea over time compared with the Cu-IUD, some will experience longer and more frequent bleeding.  Cu-IUD can cause menorrhagia, especially in the first few months of use.  Discontinuation rates for 52mg LNG-IUS and Cu-IUD are similar.  There is some evidence to suggest bleeding patterns in all IUC will improve/settle with time after insertion, but it remains one of the most common reasons cited for removal, with 20% of women complaining or irregular or heavy bleeding after 1 year. 

Recurrent vaginal infections, bacterial vaginosis and candida infection, can be a problem, especially with Cu-IUD, and cessation should be discussed with the patient if this is the case.

Some women report hormonal side effects such as acne, headaches, reduced libido, weight gain, breast tenderness and mood changes, though discontinuation rates for side effects is similar for both Cu-IUD and LNG-IUS.

The insertion procedure itself can be painful for the woman and some will experience a vasovagal reaction, bradycardia or other arrhythmia.  While this will resolve in most women with simple resuscitation measures, rarely the bradycardia persists and iv/im may be needed.


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