What are the guidelines for inserting an IUD in a patient who is eight days late on their menstrual cycle after unprotected intercourse?

IUD Insertion Guidelines for Late Menses with Recent Unprotected Intercourse

In a patient who is 8 days late on her menstrual period after unprotected intercourse, you should first perform a urine pregnancy test and, if negative, can proceed with copper IUD insertion as emergency contraception, which remains highly effective up to 5 days after unprotected intercourse (or up to 5 days after the estimated ovulation date). 1

Assessing Pregnancy Status

Before IUD insertion, you must be reasonably certain the patient is not pregnant. The CDC provides specific criteria to rule out pregnancy with 99-100% negative predictive value: 1

• If the patient had unprotected intercourse within the last 5 days, strongly consider emergency contraception (including copper IUD) rather than waiting for pregnancy test confirmation 1
• A negative urine pregnancy test alone may not be sufficient if the patient doesn't meet other clinical criteria, as the test may not detect very early pregnancy 1
• Routine pregnancy testing is not always necessary if the patient meets specific clinical criteria, though clinical judgment may warrant testing 1

Critical Timing Consideration

The copper IUD can be inserted within 5 days of unprotected intercourse as emergency contraception, and when ovulation day can be estimated, can be inserted beyond 5 days after intercourse as long as insertion occurs within 5 days after ovulation. 1

Emergency Contraception Window

For this patient who is 8 days late:

• If the unprotected intercourse occurred within the last 5 days, the copper IUD is the most effective emergency contraception option and can be inserted immediately 1
• If intercourse occurred more than 5 days ago but within 5 days of her estimated ovulation, copper IUD insertion is still appropriate 1
• The copper IUD is highly effective as emergency contraception and can be continued as regular contraception 1

Evidence on Cycle Timing and IUD Insertion

Research demonstrates that copper IUD insertion timing during the menstrual cycle has minimal effect on contraceptive continuation, effectiveness, or safety: 2

• IUD insertion can occur at any time during the menstrual cycle provided the woman is not pregnant 3
• There is no justification for requiring IUD insertion only during menses 4
• A study of 1,840 women receiving copper IUD for emergency contraception showed zero pregnancies in the first month, regardless of cycle timing, when pregnancy test was negative prior to insertion 5

Clinical Algorithm

Step 1: Determine timing of unprotected intercourse

• If within 5 days: Proceed with pregnancy assessment for emergency IUD 1
• If beyond 5 days: Estimate ovulation date based on her typical cycle length 1

Step 2: Perform urine pregnancy test

• If negative and unprotected intercourse was recent (within emergency contraception window): Proceed with copper IUD insertion 1, 5
• If positive: Do not insert IUD 3

Step 3: Insert copper IUD

• Can be inserted immediately if pregnancy is reasonably excluded 3, 5
• Perform bimanual examination and uterine sounding before insertion 3

Important Caveats

Pregnancy test limitations: Standard urine pregnancy tests may not detect pregnancy on the first day of missed period, with most products detecting only 16% or less of pregnancies at this early stage 6. Only the most sensitive tests (6.3 mIU/mL sensitivity) detect >95% of pregnancies on the day of missed period 6.

For patients with irregular cycles: Women with cycles consistently outside 26-32 days have higher pregnancy risk, and the fertile window timing varies greatly even among women with regular cycles 1. For a patient 8 days late, this suggests either pregnancy or an irregular cycle requiring careful assessment 7.

Contraindications to assess: Pregnancy, unexplained vaginal bleeding, and lifestyle factors placing the woman at risk for sexually transmitted diseases are contraindications to IUD use 3.