From the Guidelines
An IUD is most likely to not be positioned in the fundus correctly due to anatomical abnormalities, such as a distorted uterine cavity, which can preclude proper IUD placement 1. Several factors can contribute to the malpositioning of an intrauterine device (IUD), including:
- Clinician inexperience or improper insertion technique, which requires specific training and skill to accurately place the device
- Anatomical variations, such as an extremely anteverted or retroverted uterus, uterine anomalies like fibroids or septa, or a distorted uterine cavity, which can make proper placement challenging 1
- Post-insertion factors, including uterine contractions that may gradually push the IUD downward, particularly during menstruation
- The timing of insertion, with insertion during menstruation potentially increasing displacement risk due to a more dilated cervix
- IUD characteristics, such as larger devices being more prone to displacement in smaller uterine cavities To minimize malpositioning risk, insertion should be performed by trained providers using ultrasound guidance when necessary, especially in patients with known uterine anomalies 1. Proper follow-up with ultrasound verification of placement is recommended, particularly when patients experience unusual symptoms like excessive bleeding, pain, or when strings are not visible during examination. Key considerations for minimizing malpositioning risk include:
- Using ultrasound guidance to ensure high fundal placement of the IUD, which has been shown to decrease expulsion rates 1
- Selecting the appropriate IUD size for the patient's uterine cavity to reduce the risk of displacement
- Providing proper training and skill for clinicians performing IUD insertions to ensure accurate placement.
From the Research
Causes of IUD Malposition
- Uterine structural abnormalities, such as congenital anomalies and fibroids, can lead to IUD malposition 2
- Retroflexed uterine positions and all uterine malformations are associated with a higher incidence of malpositioned IUDs 2
- Presence of increased number of fibroids, specifically submucosal fibroids, is positively associated with IUD malposition 2
- Symptoms of bleeding, pain, and missing IUD strings at time of presentation are associated with an increased risk of malposition 2
- Previous cesarean delivery is significantly associated with a malpositioned IUD, after adjusting for confounders 3
- Uterine retroflexion and a large cesarean scar defect are independent risk factors for IUD malposition among persons with prior cesarean delivery 3
Ultrasonography in IUD Malposition
- Ultrasonography serves as first-line imaging for the evaluation of IUD position in patients with pelvic pain, abnormal bleeding, or absent retrieval strings 4
- Three-dimensional ultrasonography has proven to be more sensitive in the evaluation of subtle findings of malposition, particularly side-arm embedment 4, 5
- A 3D coronal view of the uterus is useful in the visualization of IUDs and may help in identifying the cause of pelvic pain and bleeding in patients with an embedded IUD 5
Uterine Dimensions and IUD Malposition
- Uterine dimensions, such as uterine width, can be used to predict IUD displacement or expulsion before it happens 6
- Women with a uterus width less than 41.5 mm are more likely to have displacement 6
- IUD endometrium distance is an important parameter for displacement, with a distance of 7.5 mm or more being associated with a higher risk of displacement 6