Information on
Intramural Pregnancy
What is an IMP?
Intramural pregnancy (IMP) is a rare and potentially life-threatening type of uterine ectopic pregnancy in which the gestational sac implants within the myometrium of the uterine corpus—above the internal cervical os and separate from the interstitial portion of the fallopian tubes. The defining feature of IMP is implantation beyond the endometrial–myometrial junction (EMJ). Some people also refer to IMP as a myometrial pregnancy, subperitoneal pregnancy, or subserosal pregnancy.
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Types of IMP
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IMP can be broadly classified into two main types, based on guidance from the European Society of Human Reproduction and Embryology. While alternative classification systems exist, this framework is the most commonly referenced:
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Partial IMP: The gestational sac is implanted within the myometrium but maintains a visible connection with the endometrial cavity.
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Complete IMP: The gestational sac is entirely embedded within the myometrium, with no communication with the endometrial cavity.
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Incidence and Risk Factors
IMP is exceptionally rare, with approximately 100 cases reported in the English-language medical literature. The most recognised risk factor is prior disruption of the EMJ, often due to procedures such as transcervical suction curettage. However, up to 29% of cases occur without any identifiable cause.
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Maternal Risks and Complications
Due to its abnormal anatomical location, IMP poses significant risks, including:
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Uterine rupture
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Severe hemorrhage
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Emergency hysterectomy
Prompt diagnosis and management are essential to reduce maternal morbidity.
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Diagnostic Challenges
IMP often mimics other conditions—such as interstitial pregnancy, fibroids, or gestational trophoblastic disease—making diagnosis difficult. Timely diagnosis requires expert imaging and a high index of clinical suspicion.
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Management and Treatment
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Currently, there are no standardised clinical guidelines for the management of IMP. Treatment decisions are typically guided by institutional experience, available resources, and the patient’s clinical condition.
Management options include:
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Expectant management: may be appropriate in selected, clinically stable cases with close monitoring.
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Medical management: may involve local or systemic methotrexate, or potassium chloride injection.
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Surgical intervention: options include transcervical suction curettage, hysteroscopic resection, laparoscopic or open surgical resection, and, when necessary, planned or emergency hysterectomy.
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Other approaches: including uterine artery embolisation.
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Why Early Recognition Matters
Early diagnosis and timely referral to specialist centers can significantly improve outcomes. Given the potential severity of complications, multidisciplinary care may be required.
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Join the IMP Registry
The Intramural Pregnancy Registry aims to collect and share data on this rare condition to improve diagnosis, management, and outcomes.
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Are you a clinician or researcher with experience managing an IMP case? We encourage you to get involved.​​​
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