The Lippes Loop was one of the most widely used intrauterine devices in the world from the 1960s through the 1980s, a simple S-shaped plastic coil that sat inside the uterus and prevented pregnancy without hormones or copper. Designed by American physician Jack Lippes in 1962, it was made entirely of polyethylene and relied on the body’s own inflammatory response to create an environment hostile to fertilization. Although it has been largely replaced by copper and hormonal IUDs with better pregnancy prevention rates, the Lippes Loop remains medically relevant today because thousands of devices inserted decades ago are still inside their users, sometimes forgotten entirely.
What the Lippes Loop Looked Like and How It Was Used
The device was a double-S or zigzag-shaped piece of flexible polyethylene plastic, with a thin nylon tail string hanging through the cervix so a clinician could check placement or remove it. It came in four sizes, labeled A through D, with A being the smallest and D the largest. The size chosen depended on the woman’s anatomy and whether she had previously given birth. A key selling point was durability: because it contained no medication, it did not need to be replaced on a schedule. Once inserted, it could theoretically remain in the uterus indefinitely, and many women kept theirs for decades.
Insertion was done in a clinical setting, typically during or just after menstruation when the cervix was slightly more open. The loop was straightened inside a narrow plastic tube, passed through the cervical canal, and released into the uterine cavity, where it sprang back into its coiled shape. The procedure was quick but not always painless, and the skill of the clinician mattered: in a large survey of over 276,000 Lippes Loop insertions in Taiwan, most confirmed cases of uterine perforation involved insertion by less experienced providers, and four out of five patients in a detailed case series reported pain or bleeding during the procedure itself.
How It Prevented Pregnancy
The Lippes Loop worked not by releasing any drug but by provoking a sustained low-grade inflammatory reaction inside the uterus. The presence of a foreign object in the uterine cavity triggers the immune system to flood the area with white blood cells and other inflammatory cells. This reaction changes the local environment enough to impair sperm transport and make the uterine lining less hospitable to a fertilized egg. A review of endometrial tissue from IUD users found that both inert and copper-bearing devices caused infiltration of immune cells into the uterine lining, along with surface ulceration, small hemorrhages, and clotting in tiny blood vessels.1PubMed. Endometrial morphological changes in IUD users: a review
This mechanism was less targeted than what modern copper IUDs achieve. Copper ions are directly toxic to sperm and add a biochemical layer of contraception on top of the foreign-body reaction. The Lippes Loop, having no copper or hormones, depended entirely on that inflammatory response, which partly explains why its pregnancy rates were higher than those of later devices.
Effectiveness Compared to Copper IUDs
The Lippes Loop was a reasonably effective contraceptive, but it was not as reliable as the copper-bearing IUDs that eventually replaced it. A ten-year study in Yugoslavia compared the standard Lippes Loop to a modified version with added copper wire. After one year, the accidental pregnancy rate was about 4.6 per 100 women for the standard loop, compared to roughly 0.6 per 100 for the copper-bearing version. By ten years, the gap widened considerably: about 15 pregnancies per 100 women with the standard loop versus under 4 per 100 with added copper.2PubMed. The effect of adding copper onto Lippes Loop IUDs: results from a ten-year study in Yugoslavia
A multicenter trial in developing countries found a similar pattern when comparing the Lippes Loop to the TCu 380A, which remains one of the most widely used copper IUDs today. At twelve months, pregnancy rates were about 2.1 per 100 women for the Lippes Loop and 0.7 per 100 for the TCu 380A.3Contraception. Clinical performance of the TCu 380A and Lippes Loop IUDs in three developing countries The difference was not large enough to reach statistical significance in that particular trial, but it was consistent with findings from other studies. For women who wanted effective contraception beyond five years, however, some researchers argued the Lippes Loop was the better choice because it never needed replacing, while copper devices gradually lost their copper coating.4PubMed. Comparison of copper T-200 with Lippes loop as a contraceptive device
Expulsion Rates and the Problem of Size
One of the Lippes Loop’s persistent weaknesses was expulsion, where the device slipped partly or completely out of the uterus on its own. This happened most often in the first few months after insertion and was strongly influenced by the size of the device relative to the uterus. Smaller loops were expelled much more frequently than larger ones. Early data showed first-year expulsion rates of about 21 percent for the smaller size versus roughly 8 percent for the larger size.5American Journal of Obstetrics and Gynecology. Contraception with intrauterine plastic loops
Age and childbearing history also mattered. A study of 284 Lippes Loop users found that both removal rates and expulsion rates dropped as women got older and had more children, likely because the uterine cavity in women who have given birth is larger and better able to accommodate the device.6PubMed. A study of 284 cases of Lippes loop This created a clinical dilemma: younger women who had not yet had children were the ones most likely to want long-acting contraception but also the most likely to expel the device.
The copper-bearing modification of the Lippes Loop improved expulsion rates dramatically. In the Yugoslav ten-year study, expulsion and displacement rates after one year were about 4.5 per 100 women with the copper version versus roughly 12.6 per 100 with the standard plastic loop. By ten years, the gap was even wider.7PubMed. The effect of adding copper onto Lippes Loop IUDs: results from a ten-year study in Yugoslavia
Heavier Periods and the Bleeding Problem
The most common complaint among Lippes Loop users was heavier menstrual bleeding. All non-hormonal IUDs tend to increase menstrual flow, but the Lippes Loop was one of the worst offenders. Quantitative studies measured average menstrual blood loss in women without contraception at about 32 milliliters per cycle. With the Lippes Loop and similar inert devices, that average jumped to roughly 52 to 72 milliliters over the first two years of use.8Contraception. Quantitative studies on menstrual blood loss in IUD users
A comparative study in The Lancet put finer numbers on this. Among women who had previously given birth, the Lippes Loop increased average menstrual blood loss by about 48 milliliters per cycle. By comparison, the Copper 7 device increased blood loss by about 18 milliliters, and the Dalkon Shield fell in between at roughly 34 milliliters. The proportion of Lippes Loop users losing more than 80 milliliters per cycle (the clinical threshold for heavy menstrual bleeding) was higher than for either of the other devices, and the incidence of anemia during the first year of use was correspondingly greater.9PubMed. Menstrual blood-loss with intrauterine devices
Researchers traced part of the explanation to changes in how blood clots inside the uterus. Menstrual blood from Lippes Loop users showed higher fibrinolytic activity, meaning the body broke down blood clots faster in the uterine lining. This resulted in less stable clot formation and more prolonged bleeding compared to copper IUD users.10PubMed. Fibrinolytic activity of menstrual blood in normal and menorrhagic women and in women wearing the Lippes Loop and the Cu-T (200) For many women, especially those in settings where iron supplementation was not readily available, the extra blood loss was reason enough to have the device removed.
Perforation and Serious Complications
Uterine perforation, where the device pushes partly or entirely through the wall of the uterus, was a rare but serious complication. The large Taiwanese dataset of over 276,000 insertions identified 14 confirmed cases of loop displacement through the uterine wall. In several of those cases, the site of perforation was on the wall opposite to the direction the uterus naturally tilted, suggesting the inserting instrument pressed against the thinner side. Insertion during early, unrecognized pregnancy appeared to raise the risk, as the pregnant uterus is softer and more vulnerable to puncture.11American Journal of Obstetrics and Gynecology. Perforation of the uterine wall by the Lippes loop: Its frequency and mechanism
A perforated IUD that migrates into the abdominal cavity can sit there without symptoms for years or even decades. One case report described a 67-year-old woman who had carried a Lippes Loop for 35 years without any gynecological follow-up. She arrived at the hospital with severe abdominal pain that initially looked like a perforated stomach ulcer. During surgery, doctors found the tip of the Lippes Loop poking through two small holes in the top of her uterus, with infected fluid throughout the abdomen. The infection turned out to be actinomycosis, a slow-growing bacterial infection strongly associated with long-retained IUDs. She required a full hysterectomy.12PubMed. Uterine perforation with Lippes loop intrauterine device-associated actinomycosis: a case report and review of the literature
Infection Risk and the Tail String Debate
For years, a major concern was that the tail string of an IUD might act as a wick, drawing bacteria from the vagina up through the cervical canal and into the uterus. This fear intensified after the Dalkon Shield disaster of the 1970s, in which that device’s braided multifilament tail was linked to serious pelvic infections and several deaths. The Lippes Loop used a monofilament nylon string, which was structurally different and less likely to harbor bacteria between its fibers. Still, the suspicion lingered.
A pooled analysis specifically examined whether IUDs with tail strings had higher rates of pelvic inflammatory disease than tailless models. The result showed no meaningful increase in infection rates for IUDs with tails compared to those without, with the relative risk at about 1.2 and the confidence interval crossing 1.0, meaning the difference could easily be due to chance. Similarly, different tail string materials showed no difference in infection rates.13PubMed. Evidence against tailstrings increasing the rate of pelvic inflammatory disease among IUD users The fear of string-related infection turned out to be largely unfounded for monofilament designs, though any IUD left in place for an extremely long time without monitoring can become a nidus for unusual infections like actinomycosis.
The Forgotten Loop Problem
Because the Lippes Loop had no expiration date, many women simply left theirs in place through menopause and beyond. Some forgot they had one. Others assumed it no longer mattered once they stopped menstruating. Decades later, these forgotten devices can cause problems that are disproportionate to their simplicity.
Over time, polyethylene plastic accumulates small calcium deposits. This corrosion compromises the strength of both the device body and the tail string, making the loop brittle and prone to fracture. The device also tends to become embedded in the endometrium, which means that removing it is no longer a simple matter of pulling on the string. Attempted extraction can cause pain and bleeding, and if the string has broken off, removal may require hysteroscopy or even surgery.14PubMed Central. Lippes loop intrauterine device left in the uterus for 40 years as a rare cause of postmenopausal pelvic pain: a case report and review of the literature In extreme cases, the calcification can be so extensive that the entire device becomes a calcified mass visible on imaging.15PubMed Central. Calcified retained intrauterine device in the setting of a vesicovaginal fistula
The clinical dilemma with these retained devices is real: is it safer to attempt removal in an elderly woman, with the attendant risks of anesthesia and uterine injury, or to leave a silent piece of calcified plastic in place? Case reports and reviews have gone back and forth on this question. The general consensus leans toward removal when a woman has symptoms like postmenopausal bleeding or pelvic pain, and toward watchful waiting when the device was discovered incidentally and is causing no trouble. But “no trouble” is hard to guarantee, given the association with actinomycosis and the rare but documented occurrence of endometrial pathology in women with long-retained devices.
Postmenopausal Bleeding and Endometrial Concerns
When a postmenopausal woman with a forgotten Lippes Loop develops vaginal bleeding, the device itself is not necessarily the cause, but it complicates the picture. Postmenopausal bleeding always warrants investigation because it can signal endometrial cancer. At least one case report documented endometrial adenocarcinoma in a woman who presented with postmenopausal bleeding and was found to have a forgotten Lippes Loop in place. The authors emphasized that while a causal link between the IUD and the cancer is not established, endometrial sampling should be performed in any postmenopausal woman with bleeding and an IUD still in the uterus.16Journal of South Asian Federation of Obstetrics and Gynaecology. Forgotten Lippes Loop associated with Endometrial Carcinoma
On the other hand, long-term cytological monitoring of women using various contraceptive devices, including the Lippes Loop, found no cases of severe dysplasia or malignancy over follow-up periods ranging from six months to fifteen years. The incidence of any cervical dysplasia among Lippes Loop users was about 1.8 percent, which was among the lowest of all devices tested and not meaningfully different from the pre-treatment rate of 1.4 percent.17PubMed. Cervical carcinogenesis and contraception The data suggest the device itself does not drive cancer risk, but a forgotten IUD that discourages a woman from seeking routine gynecological care could indirectly delay diagnosis of unrelated pathology.
Imaging a Lippes Loop
Because the Lippes Loop is made of polyethylene without any metal components, it is not visible on a standard X-ray unless barium or another radiopaque marker was embedded in the plastic, as some later production runs included. Ultrasound is the first-line imaging method for evaluating any IUD’s position. On ultrasound, the Lippes Loop appears as a series of bright echogenic lines within the uterine cavity, and its distinctive zigzag shape is usually recognizable to an experienced sonographer. Three-dimensional ultrasound has proven more sensitive for detecting subtle problems like partial embedding or displacement than conventional two-dimensional scans.18PubMed Central. Ultrasonography of intrauterine devices
When a device has perforated the uterus and migrated into the abdomen, ultrasound alone may not locate it. CT or MRI can be helpful in those scenarios, though the plastic material does not produce the strong signal that a copper device would on CT. Calcification of a long-retained loop, paradoxically, can make it easier to spot on imaging, since calcium deposits show up clearly on both X-ray and CT.
Fertility After Removal
One question women had, and still occasionally have when a decades-old Lippes Loop is discovered and removed, is whether the device caused lasting damage to fertility. The inflammatory changes the loop provoked in the endometrium were reversible in principle, but the timeline of recovery is not entirely clear. Research on endometrial gene expression after IUD removal has shown that changes in receptivity markers can persist for up to a year after removal of an inert device.19PubMed Central. Levonorgestrel IUD: is there a long-lasting effect on return to fertility? For women of reproductive age who had a Lippes Loop removed, fertility generally returned, though the exact timeline varied. The endometrial inflammation resolved, the immune cell infiltration receded, and the lining gradually returned to its normal cycling state. For older women whose devices have been in place for decades, the fertility question is usually moot, but the finding underscores that the device’s effects on the uterine lining were not trivial even after removal.
Why the Lippes Loop Disappeared
The Lippes Loop was never banned or recalled in the dramatic fashion of the Dalkon Shield. Its exit from the market was more gradual, driven by the arrival of copper IUDs in the 1970s and hormonal IUDs in the 1980s and 1990s that offered lower pregnancy rates, less bleeding, and smaller profiles. The TCu 380A, for example, achieved pregnancy rates roughly a third of what the Lippes Loop produced while causing less menstrual blood loss. Hormonal IUDs like the levonorgestrel-releasing system went further, often reducing menstrual bleeding to a fraction of normal.
Manufacturing of the Lippes Loop wound down in many countries by the late 1980s and 1990s, though it remained available longer in parts of South Asia and sub-Saharan Africa where its low cost and indefinite lifespan were practical advantages. In India, it was a mainstay of government family planning programs for decades. Even after production largely ceased, the device’s legacy persists in the form of retained loops in aging women around the world. Gynecologists in countries where the Lippes Loop was heavily distributed continue to encounter them, sometimes with surprise, during routine exams or when investigating pelvic symptoms in postmenopausal patients.