A woman was rushed to surgery after her contraceptive implant had moved from her arm to her lung.

In a “very rare” incident, the 31-year-old from Portugal had gone to the hospital because of unusual bleeding from her vagina.

She had used the contraceptive implant for eight years but suddenly experienced bleeding for three months.

When she arrived at the hospital, doctors were unable to locate the implant, a small hard rod which remains in place releasing hormones for three years, in her arm.

The perplexed doctors, from the gynecology department of a hospital in Viana do Castelo, then performed a CT scan and the rod bizarrely showed up in the bottom of the woman’s left lung.

Their report suggested the device could have shifted out of place and into the veins and arteries.

They wrote: “Risk factors for [implant] migration are placement technique – if introduced deeply migration can occur into the venous system and then to the pulmonary arterial system.”

“And the practice of vigorous physical exercise after correct placement, which seems to increase the risk of vascular migration.”

Traveled in the bloodstream

They suggest the implant was placed too deep into the arm and it was absorbed by a blood vessel before traveling through the body in her bloodstream.

She was not made ill by the movement and recovered quickly from surgery, being released from the hospital after four days.

They were unable to explain what had caused the bleeding, but suspect the device had become ineffective so her period resumed.

“Few cases” have been described in medical reports, the Portuguese doctors said in their paper in the journal BMJ Case Reports.

But similar cases have been reported and experts say women should check the placement of their implant regularly.

Dr. Tania Adib, a consultant gynecologist at the Kensington Medical Chambers, said: “The risk of the contraceptive implant traveling is extremely low.”

“Risk is higher if it isn’t placed beneath the skin properly e.g. it is placed too deeply.”

“The risk is higher in women who are very thin and those who are placing the implants should have specific training in how to insert them properly to reduce the risk. Women should also check their arms regularly to ensure they can feel the implant and if they can no longer feel it they should check this.”