Interstitial pregnancy: role of MRI

Heterotopic Interstitial Pregnancy: Early Ultrasound Diagnosis of 179 Cases After In Vitro Fertilization-Embryo Transfer

OBJECTIVES

What is the role of transvaginal sonography (TVS) in the early diagnosis of hectopic interstitial pregnancy (HIP) after in vitro fertilization-embryo transfer (IVF-ET)?

METHODS

A retrospective observational study was conducted from January 2005 to December 2018. Routine two-dimensional and three-dimensional TVS were used to confirm clinical pregnancy. Women were diagnosed with HIP when an intrauterine gestational sac was combined with an extrauterine chorionic sac, which was at least 1 cm away from the uterine cavity and surrounded by a thin myometrial layer (<5 mm). Surgery and pathology results were the gold standard for diagnosing interstitial pregnancy. Non-surgical patients were excluded from the study. The performance of TVS and the pregnancy outcomes of intrauterine pregnancies (IUPs) were evaluated.

RESULTS

A total of 97,161 women underwent IVF treatment and TVS examinations in our hospital during this study. Of these, 194 patients were diagnosed with HIP, with an incidence of 0.2% (194/97,161). Surgical and pathological findings confirmed 179 interstitial pregnancies, of which 174 were diagnosed by TVS, 4 were missed, and 1 was misdiagnosed. The sensitivity of TVS diagnosis was 97.8% and the positive predictive value was 99.4%. The mean time to diagnosis was 31 days after transplantation. One hundred and thirty-nine cases of HIP (77.7%) were diagnosed at the time of initial TVS examination. In 132 patients (73.7%), IUPs resulted in live births.

CONCLUSIONS

In our practice, most HIPs following IVF-ET can be accurately diagnosed by TVS, which facilitates early management of interstitial pregnancies and enables high live birth rates for IUPs.

Sonographic diagnosis of an interstitial pregnancy in an asymptomatic patient at 7 weeks' gestation

An interstitial pregnancy is an ectopic pregnancy located within the proximal intramural segment of the Fallopian tube traversing the myometrium. This type of ectopic pregnancy is relatively rare, occurring in approximately 1%-3% of all ectopic pregnancies. Given the myometrial mantle surrounding the gestational sac, which is considerably thicker than in other tubal pregnancies, patients with interstitial pregnancies classically manifest symptoms later in gestation. Thus, there is an increased risk of life-threatening intraperitoneal hemorrhage upon rupture of the myometrium encompassing the pregnancy. We present an unusual case of early sonographic diagnosis of an interstitial pregnancy in an asymptomatic patient at 7 and 3/7 weeks’ gestation, discuss predisposing factors, hallmarks of sonographic diagnosis, and review the literature regarding available clinical management modalities. With the increasing application of point of care ultrasound (POCUS) by emergency room physicians and other providers in outpatient facilities, our case emphasizes both the importance of correct sonographic identification of interstitial pregnancy and the clinical importance of uniform early first-trimester sonography, preferably no later than 7-8 weeks’ gestation.

Using MRI to differentiate upper-lateral intracavitary pregnancy and interstitial pregnancy for the patients with pregnancies in the uterotubal junction during the first trimester

Objectives

To retrospectively evaluate the diagnostic value of MRI for the uterotubal junctional pregnancies during the first trimester.

Methods

This retrospective study involved 59 patients (January 2016 to July 2021) with a preoperative imaging diagnosis of uterotubal junctional pregnancy. Using operative and pathological reports as the reference standard, we identified 22 patients with upper-lateral intracavitary (angular) pregnancy and 37 patients with interstitial pregnancy. Two senior radiologists, blinded to the patients’ information, reviewed the MRI images and determined each MRI feature based on the original interpretation criteria. Any disagreement was resolved by discussion to achieve a consensus. The sensitivity and specificity of each MRI feature were calculated according to the reference standard.

Results

The endometrial thickness in the upper-lateral intracavitary pregnancy group was larger than in the interstitial group (p = 0.001). The cutoff value of the endometrial thickness was 11.5 mm with a sensitivity, specificity, and area under the curve that were 77.3%, 64.9%, and 0.743, respectively. Two key features to diagnose upper-lateral intracavitary pregnancy were “medial free edge” and “medial free edge plus above-cutoff endometrial thickness.” The sensitivity and specificity of the medial free edge were 100% and 94.9%, respectively. The sensitivity and specificity of the medial free edge plus above-cutoff endometrial thickness were 77.3% and 100%, respectively. The key feature to diagnose interstitial pregnancy was an “intact lateral junctional zone,” of which the sensitivity and specificity were 94.6% and 100%, respectively.

Conclusions

MRI can be used to differentiate the upper-lateral intracavitary pregnancy and interstitial pregnancy during the first trimester.

Key Points

• We demonstrated MRI diagnostic criteria for the interstitial pregnancy and upper-lateral intracavitary pregnancy.

• MRI might be used to identify the complex interstitial pregnancies, those with a gestational sac protruding into the uterine cavity.

The role of three-dimensional MRI in the differentiation between angular pregnancy and interstitial pregnancy

Background

In clinical practice it is an ongoing challenge to distinguish between angular pregnancy and interstitial pregnancy. With the three-dimensional (3D) magnetic resonance imaging (MRI) being increasingly used, it is worth exploring its role in differentiating angular pregnancy from interstitial pregnancy. This study aims to investigate how 3D MRI can help reveal the differences between these two special pregnancies in the early diagnosis.

Methods

We reviewed and analyzed the 3D MRI images of 50 patients with interstitial pregnancy and 55 patients with angular pregnancy retrospectively. Imaging features were identified to compare these two special pregnancies, and the ROC (Receiver Operating Characteristic) analysis was conducted to assess the diagnostic performance.

Results

The significant differences of the 3D MRI imaging features between interstitial pregnancy and angular pregnancy were found in the outline of uterus cavity (p < 0.001), involvement of junctional zone (p < 0.001), the signal of surroundings (p = 0.005), the relationship with round ligament (p = 0.042), and the overlying myometrial thickness (p = 0.041). Furthermore, the multivariate logistic regression analysis identified a series of significant indicators for angular pregnancy, including the junctional zone involvement, being-surrounded by hyper/iso-intensity on 3D images, and the asymmetric outline of uterus cavity. Combining these three imaging features, the AUC (Area under the Curve) of ROC curve was 0.87 in distinguishing interstitial pregnancy from angular pregnancy.

Conclusions

This study suggests that 3D MRI can help distinguish angular pregnancy from interstitial pregnancy in clinical practice, with the advantages that conventional MRI or ultrasound does not have. Through the significant image features, 3D MRI plays an important role in improving the timing of diagnosis, avoiding unnecessary interventions, and preventing hemorrhage in clinical practice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04470-z.

Diagnosis and Management of Ectopic Pregnancy: A Comparative Review of Major National Guidelines

Importance

Ectopic pregnancies (EPs) represent a severe early pregnancy complication that is associated with increased risks of maternal morbidity and mortality. Over the years, there has been a significant reduction in the mortality from this complication by improving the diagnostic tools and the treatment options.

Objective

The aim of this study was to review and compare the recommendations from published guidelines on this potentially fatal condition.

Evidence Acquisition

A descriptive review of guidelines from the Royal College of Obstetricians and Gynaecologists, the Royal College of Physicians of Ireland, the Society of Obstetricians and Gynaecologists of Canada, the American College of Obstetricians and Gynecologists, and the National Institute for Health and Care Excellence on EP was carried out.

Results

All the guidelines point out the crucial role of sonography in the prompt diagnosis of EP and describe similar sonographic findings. There is a consensus on the indications and contraindications to the use of methotrexate, the post-treatment surveillance, and the criteria of expectant management. The indications for a surgical approach are not well established, although the Royal College of Obstetricians and Gynaecologists, the Royal College of Physicians of Ireland, the American College of Obstetricians and Gynecologists, and the National Institute for Health and Care Excellence agree that a laparoscopy is preferred to laparotomy for hemodynamically stable patients. The latter is considered a better option only in emergency conditions. However, there is controversy in the recommended methotrexate protocols and the evaluation of β-human chorionic gonadotrophin and progesterone levels.

Conclusion

It is of paramount importance to build consistent international protocols, so as to help clinicians all over the world diagnose EPs in the most timely and accurate way and subsequently treat them effectively as a nonurgent medical condition, with the intention to lower the mortality and morbidity rate.

The many faces of ectopic pregnancies: demystifying the common and less common entities

Ectopic pregnancy is a major cause of 1st trimester pregnancy deaths. It occurs in various locations in the abdominopelvic cavity. Ultrasonography is a first-line, rapid, and noninvasive modality for ectopic pregnancy evaluation. MRI can help clarify equivocal cases. When in doubt about the location, one should give an intrauterine pregnancy the benefit of the doubt with close ultrasound and hCG follow-up. Here, we will review the imaging findings and mimickers of ectopic pregnancies.

Interstitial Pregnancy in the Third Trimester with Severe Preeclampsia: A Case Report and Literature Review

An interstitial pregnancy that continues beyond the second trimester is a rare phenomenon. We report a patient with an interstitial pregnancy undiagnosed until the third trimester. A multiparous woman was referred to us because of preeclampsia at 26 weeks of gestation. The placental position was the right fundus, and color Doppler ultrasound revealed myometrial thinning and subplacental hypervascularity, leading to a suspicion of placenta accreta spectrum (PAS). Emergency cesarean section was performed at 28^1/7 weeks of gestation due to severe preeclampsia. The right tubal horn to the isthmus of the fallopian tube bulged with placental adhesion and a part of the tube had ruptured, with the omentum adhering to the ruptured part. Interstitial and tubal isthmic pregnancy with uterine rupture was diagnosed.

Multimodality imaging of acute locoregional and systemic complications in the setting of assisted reproduction

Over the past 40 years since the first in vitro fertilization was performed, both the role of assisted reproductive technology (ART) in establishing viable pregnancy as well as the available treatment options have expanded enormously. Annually in the USA, nearly 2% of pregnancies now employ some form of ART assistance, with in vitro fertilization (IVF) being the most commonly utilized methodology. Both maternal and fetal risks are elevated in ART pregnancies, the latter including adverse outcome due to both increased gestational number as well as advanced maternal age. Maternal risks may be divided into locoregional and systemic complications. Adverse pelvic complications include those relating to gamete harvesting and transfer, ovarian hyperstimulation, the sequela of ectopic and heterotopic pregnancies, as well as ovarian torsion, all of which are elevated in the ART cohort. Ovarian hyperstimulation syndrome is the most commonly encountered complication, with both systemic and pelvic features relating to increased vascular permeability, hemoconcentration, and ascites. While life-threatening cases are relatively rare, moderate and severe manifestations may occur in up to 10% of ART cycles and, as such, are a not infrequent cause for ER visitation. Familiarity with the clinical and imaging manifestations of ART complications as well as their prognostic implications will facilitate a timely diagnosis and assist the interpreting radiologist in best expediting appropriate clinical care. In this article, we will briefly discuss the current methodology of ART then present an imaging-based multimodality review of the potentially encountered adverse maternal sequela, highlighting key diagnostic features and differential considerations as well as potential prognostic implications.

Magnetic resonance imaging of common, uncommon, and rare implantation sites in ectopic pregnancy

OBJECTIVE

To review the MRI appearances of tubal and non-tubal implantation sites in ectopic pregnancy.

CONCLUSION

Transvaginal ultrasound is the primary imaging modality in ectopic pregnancy and MRI is used as a problem-solving tool in selected indications as detailed in the article. MRI features of tubal, interstitial, cervical, cesarean scar, cornual, ovarian, abdominal, and heterotopic pregnancies are provided to familiarize the radiologists with their appearances thereby assisting them in making early and accurate diagnosis.

Interstitial and Cornual Ectopic Pregnancy: Conservative Surgical and Medical Management

Background

Interstitial and cornual ectopic pregnancy is rare, accounting for 2-4% of ectopic pregnancies and remains the most difficult type of ectopic pregnancy to diagnose due to low sensitivity and specificity of symptoms and imaging. The classic triad of ectopic pregnancy-abdominal pain, amenorrhea and vaginal bleeding-occurs in less than 40% of patients. The site of implantation in the intrauterine portion of fallopian tube and invasion through the uterine wall make this pregnancy difficult to differentiate from an intrauterine pregnancy on ultrasound. The high mortality in this type of pregnancy is partially due to delay in diagnosis as well as the speed of hemorrhage.

Methods

Three cases of interstitial pregnancy were retrospectively analyzed.

Result

Successful laparoscopic cornuostomy and removal of products of conception were performed in two cases, while one case was successfully managed by local injection with KCL and methotrexate followed by systemic methotrexate.

Conclusion

Early diagnosis and timely management are key to the management of interstitial and cornual ectopic pregnancy. With expertise in ultrasound imaging and advances in laparoscopic skills progressively, conservative medical and surgical measures are being used to treat interstitial and cornual ectopic pregnancy successfully.

Interstitial twin pregnancy: A unique case presentation

Early recognition and timely treatment of an interstitial pregnancy is imperative to avoid the high morbidity and mortality of this type of ectopic pregnancy. We report a case of twin interstitial pregnancy that was initially missed on initial sonogram and was subsequently recognized at our institution by transvaginal sonography. The patient underwent open laparoscopic surgery with cornual wedge resection but suffered infundibulopelvic ligament hemorrhage and subsequently required ipsilateral salpingo-oophorectomy. She did well and was discharged home a day later.

Endosonography of benign myometrium cysts and cyst-like lesions

INTRODUCTION

Many pathological causes are responsible for the sonographic presentation of myometrium cysts and cyst-like lesions, where the distinction between these etiologies is required.

THE AIM OF THE WORK

The current work is aimed at discerning between different etiologies of myometrium cysts and cyst-like lesions for an optimum management.

METHODOLOGY

In the course of daily practice of gynecological transvaginal ultrasound, 66 cases of myometrium cysts and cyst-like lesions have been discerned, where all were examined with endovaginal ultrasound using a multifrequency endocavitary probe having color Doppler capability.

RESULTS

Adenomyosis uteri detected in 15 cases, invasive mole in 4 cases, congested arcuate veins in 20 cases, incidental cysts in 4 cases, cystic degeneration of myoma in 3 cases, C-section scar cysts and cyst-like lesions in 13 cases, interstitial ectopic pregnancy in 2 cases, incomplete abortion with congested myometrium vessels in 4 cases, and arteriovenous malformation in 1 case. The number of cases with cervical nabothian cysts was not considered since they were too frequent.

CONCLUSION

Endosonography is an important tool in differentiating between the various diseases that are responsible for benign myometrium cysts and cyst-like lesions, which are all important since some of them are visualized as serious clinical situations and others turn out to be of little clinical significance.

Magnetic resonance imaging for diagnosis and management of unruptured interstitial pregnancy

AIM

The aim of this study was to evaluate the value of magnetic resonance imaging (MRI) for the diagnosis and management of suspicious unruptured interstitial pregnancy.

MATERIAL AND METHODS

Only patients with unruptured interstitial pregnancy evaluated by MRI and observed for at least a year after surgery were included. Initial evaluation was performed by measurement of serum β-human chorionic gonadotrophin level and ultrasonography. In suspicious cases, emergency MRI was performed to diagnose interstitial pregnancies with the exclusion of rudimentary horn pregnancy and angular pregnancy. Three-dimensional computed tomographic (CT) angiography was additionally performed if the uteroplacental neovascularization needed to be evaluated. Then, management procedures were individually determined along with the need for preoperative transcatheter arterial chemoembolization for immediate devascularization, and for the local or systemic administration of methotrexate. Either laparoscopic cornuostomy or cornual resection was chosen to excise the gestational mass.

RESULTS

Five consecutive women with unruptured interstitial pregnancy were enrolled. One case each of rudimentary horn pregnancy and angular pregnancy was excluded. Three-dimensional CT angiography was performed in three cases due to increased vascular flow on color Doppler ultrasonography. Preoperative devascularization by transcatheter arterial chemoembolization was performed in two cases, in which a prominent neovascularized gestational mass was identified. Uterine preservation was achieved by cornuostomy or cornual resection in all cases. Two patients with a desire to become pregnant conceived spontaneously thereafter, followed by successful cesarean birth.

CONCLUSION

This small case series emphasizes that precise localization of gestational products in the interstitial portion of the fallopian tube by MRI can facilitate the minimally invasive management of unruptured interstitial pregnancy for uterine preservation.

Magnetic resonance imaging of acute abdominal and pelvic pain in pregnancy

Evaluation of acute abdominal and pelvic pain in pregnancy presents a diagnostic challenge for clinicians and radiologists alike. The differential diagnosis includes obstetric and nonobstetric conditions unique to pregnancy, in addition to causes of acute abdominal and pelvic pain unrelated to the pregnancy. The clinical presentation and course of disease may be altered in pregnancy, and several pathologies are exacerbated by pregnancy. Discriminating clinical features in the diagnosis of abdominal and pelvic pain are often confounded by expected anatomic and physiologic changes in pregnancy. Moreover, while diagnostic pathways may be altered in pregnancy, the necessity for a timely and accurate diagnosis must be underscored, as delay in treatment may result in an undesirable increase in morbidity and/or mortality for both the patient and fetus. Advances in magnetic resonance imaging (MRI) through faster acquisition and motion-insensitive techniques, coupled with increased awareness and education regarding the value of MRI in diagnosing a wide range of pathology, have established MRI as a valuable strategy in the investigation of acute abdominal and pelvic pain in the pregnant patient. This review presents a practical approach to common obstetric and nonobstetric causes of acute abdominal and pelvic pain during pregnancy, as well as safety considerations for performing MRI in this patient population.

Interstitial pregnancy: a 'road map' of surgical treatment based on a systematic review of the literature

An electronic search concerning the surgical approach in cases of interstitial pregnancy from January 2000 to May 2013 has been carried out. Fifty three studies have been retrieved and included for statistical analysis. Conservative and radical surgical treatments in 354 cases of interstitial pregnancy are extensively described. Hemostatic techniques have been reported as well as clinical criteria for the medical approach. Surgical outcome in conservative versus radical treatment were similar. When hemostatic techniques were used, lower blood losses and lower operative times were recorded. Conversion to laparotomy involved difficulties in hemostasis and the presence of persistent or multiple adhesions. Laparoscopic injection of vasopressin into the myometrium below the cornual mass was the preferred approach.

MR imaging findings of ectopic pregnancy: a pictorial review

Because of its lack of ionizing radiation and excellent soft-tissue contrast, magnetic resonance (MR) imaging is being increasingly used in the evaluation of acute abdominal pain in the pregnant patient. Roughly 2% of all pregnancies are ectopic. Although ectopic pregnancy is usually diagnosed on the basis of a combination of clinical, laboratory, and ultrasonographic findings, it occasionally is initially identified at MR imaging. Thus, it is imperative that the radiologist should be familiar with the variable appearance of ectopic pregnancy at MR imaging and should evaluate for ectopic pregnancy at any time when (a) a patient has positive results of a pregnancy test and (b) an intrauterine pregnancy is not definitively seen. Because of potential issues of fetal safety, a conservative approach should be used for MR imaging in pregnancy. An MR imaging protocol for the evaluation of possible appendicitis in pregnant women is detailed. Specific findings that can aid in the diagnosis of ectopic pregnancy are the lack of an intrauterine pregnancy, isolated hemoperitoneum, tubal masses, hematosalpinx, and interstitial masses. In the differential diagnosis of acute abdominal pain in pregnancy, consideration should be given to the more unusual forms of ectopic pregnancy, such as angular pregnancy, cornual pregnancy, and abdominal pregnancy. Potential mimics of ectopic pregnancy include placental abnormalities, ovarian neoplasms, and corpus luteum cysts.

Successful management of unruptured interstitial pregnancy in 17 consecutive cases by using laparoscopic surgery

AIMS

To analyse the optimal laparoscopic surgical techniques for the treatment of interstitial pregnancy to minimise bleeding during the operative procedure and the safety of the subsequent pregnancy.

METHODS

Advanced bipolar coagulator was used to achieve haemostasis.

RESULTS

The mean gestational age was 55 ± 5.1 days. All 17 women with an interstitial pregnancy were successfully treated by laparoscopic surgery without any complication. No surgery was converted to laparotomy. The mean pre-operative beta-human chorionic gonadotropin (β-hCG) serum concentration was 14 696 ± 11 705 mIU/mL. This value decreased to 1911 ± 1769 mIU/mL at 3-day post-operation. Among women who underwent laparoscopic surgery, a cornual resection was performed in 16 (94.1%) cases. One (5.8%) woman underwent a laparoscopic evacuation of the conceptus and received a local injection of 10 mg methotrexate. The volume of blood loss was <25 mL in 16 cases. However, one woman experienced a rupture at the beginning of the operation and lost 250 mL of blood. The mean hospital stay was 4.5 days. Four of the nine women who chose to retain their reproductive function had subsequent normal pregnancies, but all received an elective caesarean delivery prior to labour.

CONCLUSIONS

The laparoscopic management of women with unruptured interstitial pregnancy can frequently be performed without haemorrhage or complication using advanced bipolar coagulation. The small sample of successful subsequent pregnancies demonstrates the safety and effectiveness of this technique, but this finding should be confirmed by further investigations.

Misdiagnosed uterine rupture of an advanced cornual pregnancy

Cornual pregnancy is a diagnostic and therapeutic challenge with potential severe consequences if uterine rupture occurs with following massive intraabdominal bleeding. We report a case of a misdiagnosed ruptured cornual pregnancy occurring at 21 weeks of gestation. Ultrasound examination and computer tomography revealed no sign of abnormal pregnancy. The correct diagnosis was first made at emergency laparotomy. Uterine rupture should be considered in pregnant women presenting with abdominal pain and haemodynamic instability.

Full-term interstitial retroperitoneal pregnancy with delivery of a healthy infant

Implantation in the interstitial part of the oviduct is frequently associated with severe fetal and maternal morbidity. We present a patient with primary interstitial and secondary retroperitoneal ectopic pregnancy. The suspicion of an ectopic pregnancy was raised after an ultrasound examination during the 18th week of pregnancy. An almost complete lack of symptoms led us to discard the possibility of an ectopic pregnancy. This normal-course pregnancy advanced to term. Due to anhydramnios and fetal malpresentation, a laparotomy was performed at 39 weeks of pregnancy and a healthy infant was delivered via cesarean section.

Current diagnosis and treatment of interstitial pregnancy

The incidence of interstitial pregnancy is rising. Traditional treatment with laparotomy, hysterectomy, or cornual wedge resection is associated with high morbidity and detrimental effects on future fertility. A diverse array of alternate treatments has been introduced over the last 3 decades, with the common goal of achieving a minimally invasive, standardized management strategy. This has been facilitated by impressive strides towards prompt diagnosis, both radiologically and chemically. In this review, we explore the current state of the art diagnostic criteria and the clinically significant diverse therapeutic options with supporting literature. Finally, we propose a structured, best-practice management plan for the once-lethal interstitial pregnancy, based on the current literature.

Successful management of interstitial pregnancy with fetal cardiac activity by laparoscopic-assisted cornual resection with preoperative transcatheter uterine artery embolization

INTRODUCTION

Interstitial pregnancy is a rare but dangerous form of ectopic pregnancy. Although various forms of minimally invasive management for this disorder have been previously reported, optimal treatment regimen has not been yet unknown due to its rarity.

CASE REPORT

A 29-year-old married woman with no previous disease history was referred under suspicion of ectopic pregnancy. Serum hCG value was 95,365 mIU/mL. On ultrasonographic examination, gestational sac with a viable embryo was identified in the left cornual region. Three-dimensional computed tomographic angiography showed prominent vascular mass in the left cornual region. Preoperative transcatheter uterine artery embolization followed by laparoscopic-assisted cornual resection with local methotrexate injection was successfully performed.

CONCLUSIONS

Laparoscopic-assisted cornual resection with preoperative transcatheter uterine artery embolization for interstitial pregnancy with prominent vascular flow is a safe and reliable minimally invasive procedure for woman wishing fertility preservation.

MR features of ectopic pregnancy

Ectopic pregnancy (EP), in which a fertilized ovum implants outside the uterine cavity, is the leading cause of pregnancy-related death in the first trimester. EP is usually suspected by a positive pregnancy test and an empty uterus on transvaginal sonography (TVS). Although TVS is the initial modality of choice, it may occasionally fail to demonstrate the implantation site. When TVS findings are indeterminate, magnetic resonance imaging (MRI) may provide better delineation of the focus of EP owing to its excellent tissue contrast. The key MRI features of EP include gestational sac (GS)-like structures that typically appear as a cystic sac-like structure, frequently associated with surrounding acute hematoma of distinct low intensity on T2-weighted images. In tubal pregnancy, an enhanced tubal wall on postcontrast images may be another diagnostic finding. Ruptured EP is inevitably associated with acute hematoma outside these structures. In intrauterine EP, recognition of the relationship between GS-like structure and the myometrium can aid in differentiating from normal pregnancy. Diagnostic pitfalls include heterotopic pregnancy, decidual changes in endometrial cyst and theca lutein cysts mimicking GS-like structures. Knowledge of a spectrum of clinical and MRI features of EP is essential for establishing an accurate diagnosis and determining appropriate management.

Magnetic resonance imaging of adnexal masses

Adnexal masses are common in women of all ages. A range of physiological and benign ovarian conditions that develop in women, especially in the reproductive age, and adnexal malignancies can be evaluated with magnetic resonance imaging (MRI). Management of women with adnexal masses is frequently guided by imaging findings; therefore, precise characterization of adnexal pathology should be performed whenever possible. Magnetic resonance imaging is useful in characterization of adnexal masses that are not completely evaluated by ultrasound because it can provide additional information on soft tissue composition of adnexal masses based on specific tissue relaxation times and allows multiplanar imaging at large field of view to define the origin and extent of pelvic pathology. The patients most likely to benefit from MRI are pregnant women and those who are premenopausal and have masses that have complex features on ultrasound but do not have raised cancer antigen 125 tumor marker levels. The overlap in imaging appearance among different cell type malignancies makes it difficult to predict exact histology based on MRI appearance; however, MRI has a high accuracy in differentiating benign from malignant masses. Teratomas, endometriomas, simple and hemorrhagic cysts, fibromas, exophytic or extrauterine fibroids, and hydrosalpinges can be diagnosed with high confidence. In this article, the authors review the histopathologic background and MRI features of adnexal masses and discuss the role of MRI in the differentiation of benign from malignant adnexal pathologies.