How common is IUD perforation, expulsion, and malposition?

Expulsion

IUD expulsion occurs in approximately 3% to 11% of patients.^10-13 The age of the patient influences the rate of expulsion. In a study of 2,748 patients with a Cu-IUD, the rate of expulsion by age for patients <20 years, 20–24 years, 25–29 years, 30–34 years, and ≥35 years was 8.2%, 3.2%, 3.0%, 2.3%, and 1.8%, respectively.¹⁰ In this study, age did not influence the rate of IUD removal for pelvic pain or abnormal bleeding, which was 4% to 5% across all age groups.¹⁰ In a study of 5,403 patients with an IUD, the rate of IUD expulsion by age for patients <20 years, 20–29 years, and 30–45 years was 14.6%, 7.3%, and 7.2%, respectively.¹² In this study, the 3-year cumulative rate of expulsion was 10.2%.¹² There was no statistically significant difference in the 3-year cumulative rate of expulsion for the 52-mg LNG-IUD (10.1%) and Cu-IUD (10.7%).¹²

The majority of patients who have an IUD expulsion recognize the event and seek additional contraception care. A few patients first recognize the IUD expulsion when they become pregnant, and imaging studies detect no IUD in the uterus or the peritoneal cavity. In a study of more than 17,000 patients using an LNG-IUD, 108 pregnancies were reported. Seven pregnancies occurred in patients who did not realize their IUD was expelled.¹⁴ Patients who have had an IUD expulsion and receive a new IUD are at increased risk for re-expulsion. For these patients, reinsertion of an IUD could be performed under ultrasound guidance to ensure and document optimal initial IUD position within the uterus, or ultrasound can be obtained postinsertion to document appropriate IUD position.

Malposition—prevalence and management

Our understanding of the prevalence and management of a malpositioned IUD is evolving. For the purposes of this discussion a malpositioned IUD is defined as being in the uterus, but not properly positioned within the uterine cavity. Perforation into the peritoneal cavity and complete expulsion of an IUD are considered separate entities. However, a malpositioned IUD within the uterus may eventually perforate the uterus or be expelled from the body. For example, an IUD embedded in the uterine wall may eventually work its way through the wall and become perforated, residing in the peritoneal cavity. An IUD with the stem in the cervix below the internal os may eventually be expelled from the uterus and leave the body through the vagina.

High-quality ultrasonography, including 2-dimensional (2-D) ultrasound with videoclips or 3-dimensional (3-D) ultrasound with coronal views, has greatly advanced our understanding of the prevalence and characteristics of a malpositioned IUD.^15-18 Ultrasound features of an IUD correctly placed within the uterus include:

• the IUD is in the uterus
• the shaft is in the midline of the uterine cavity
• the shaft of the IUD is not in the endocervix
• the IUD arms are at a 90-degree angle from the shaft
• the top of the IUD is within 2 cm of the fundus
• the IUD is not rotated outside of the cornual plane, inverted or transverse.

Ultrasound imaging has identified multiple types of malpositioned IUDs, including:

• IUD embedded in the myometrium—a portion of the IUD is embedded in the uterine wall
• low-lying IUD—the IUD is low in the uterine cavity but not in the endocervix
• IUD in the endocervix—the stem is in the endocervical canal
• rotated—the IUD is rotated outside the cornual plane
• malpositioned arms—the arms are not at a 90-degree angle to the stem
• the IUD is inverted, transverse, or laterally displaced.

IUD malposition is highly prevalent and has been identified in 10% to 20% of convenience cohorts in which an ultrasound study was performed.^15-18

Benacerraf, Shipp, and Bromley were among the first experts to use ultrasound to detect the high prevalence of malpositioned IUDs among a convenience sample of 167 patients with an IUD undergoing ultrasound for a variety of indications. Using 3-D ultrasound, including reconstructed coronal views, they identified 28 patients (17%) with a malpositioned IUD based on the detection of the IUD “poking into the substance of the uterus or cervix.” Among the patients with a malpositioned IUD, the principal indication for the ultrasound study was pelvic pain (39%) or abnormal uterine bleeding (36%). Among women with a normally sited IUD, pelvic pain (19%) or abnormal uterine bleeding (15%) were less often the principal indication for the ultrasound.¹⁵ The malpositioned IUD was removed in 21 of the 28 cases and the symptoms of pelvic pain or abnormal bleeding resolved in 20 of the 21 patients.¹⁵

Other investigators have confirmed the observation that IUD malposition is common.^16-18 In a retrospective study of 1,748 pelvic ultrasounds performed for any indication where an IUD was present, after excluding 13 patients who were determined to have expelled their IUD (13) and 13 patients with a perforated IUD, 156 patients (8.9%) were diagnosed as having a malpositioned IUD.¹⁶ IUD malposition was diagnosed when the IUD was in the uterus but positioned in the lower uterine segment, cervix, rotated or embedded in the uterus. An IUD in the lower uterine segment or cervix was detected in 133 patients, representing 85% of cases. Among these cases, 29 IUDs were also embedded and/or rotated, indicating that some IUDs have multiple causes of the malposition. Twenty-one IUDs were near the fundus but embedded and/or rotated. Controls with a normally-sited IUD were selected for comparison to the case group. Among IUD users, the identification of suspected adenomyosis on the ultrasound was associated with an increased risk of IUD malposition (odds ratio [OR], 3.04; 95% confidence interval [CI], 1.08-8.52).¹⁶ In this study, removal of a malpositioned LNG-IUD, without initiating a highly reliable contraceptive was associated with an increased risk of pregnancy. It is important to initiate a highly reliable form of contraception if the plan is to remove a malpositioned IUD.^16,19

In a study of 1,253 pelvic ultrasounds performed for any indication where an IUD was identified in the uterus, 263 IUDs (19%) were determined to be malpositioned.¹⁷ In this study the location of the malpositioned IUDs included¹⁷:

• the lower uterine segment not extending into the cervix (38%)
• in the lower uterine segment extending into the cervix (22%)
• in the cervix (26%)
• rotated axis of the IUD (12%)
• other (2%).

Among the 236 malpositioned IUDs, 24% appeared to be embedded in the uterine wall.¹⁷ Compared with patients with a normally-sited IUD on ultrasound, patients with a malpositioned IUD more frequently reported vaginal bleeding (30% vs 19%; P<.005) and pelvic pain (43% vs 30%; P<.002), similar to the findings in the Benacerraf et al. study.¹⁴

Connolly and Fox¹⁸ designed an innovative study to determine the rate of malpositioned IUDs using 2-D ultrasound to ensure proper IUD placement at the time of insertion with a follow-up 3-D ultrasound 8 weeks after insertion to assess IUD position within the uterus. At the 8-week 3-D ultrasound, among 763 women, 16.6% of the IUDs were malpositioned.¹⁸ In this study, IUD position was determined to be correct if all the following features were identified:

• the IUD shaft was in the midline of the uterine cavity
• the IUD arms were at 90 degrees from the stem
• the top of the IUD was within 3 to 4 mm of the fundus
• the IUD was not rotated, inverted or transverse.

IUD malpositions were categorized as:

• embedded in the uterine wall
• low in the uterine cavity
• in the endocervical canal
• misaligned
• perforated
• expulsed.

At the 8-week follow-up, 636 patients (83.4%) had an IUD that was correctly positioned.¹⁸ In 127 patients (16.6%) IUD malposition was identified, with some patients having more than one type of malposition. The types of malposition identified were:

• embedded in the myometrium (54%)
• misaligned, including rotated, laterally displaced, inverted, transverse or arms not deployed (47%)
• low in the uterine cavity (39%)
• in the endocervical canal (14%)
• perforated (3%)
• expulsion (0%).

Recall that all of these patients had a 2-D ultrasound at the time of insertion that identified the IUD as correctly placed. This suggests that during the 8 weeks following IUD placement there were changes in the location of the IUD or that 2-D ultrasound has lower sensitivity than 3-D ultrasound to detect malposition. Of note, at the 8-week follow-up, bleeding or pain was reported by 36% of the patients with a malpositioned IUD and 20% of patients with a correctly positioned IUD.¹⁷ Sixty-seven of the 127 malpositioned IUDs “required” removal, but the precise reasons for the removals were not delineated. The investigators concluded that 3-D ultrasonography is useful for the detection of IUD malposition and could be considered as part of ongoing IUD care, if symptoms of pain or bleeding occur.¹⁸

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