Unicornuate uterus represents a congenital uterine anomaly, with an incidence of approximately 0.1%-0.4% [1]. The discourse surrounding the administration of interstitial pregnancy persists as a subject of contention. This uncommon malady is on the rise in terms of frequency, encompassing approximately 2%-6.8% of all instances of ectopic gestations and comprising 2%-4% of tubal ectopic pregnancies [2-5]. The coexistence of unicornuate uterus and IEP is an exceedingly uncommon scenario, with only a handful of cases documented in the literature. The concurrent manifestation of a unicornuate uterus and an interstitial ectopic pregnancy can be ascribed to aberrations in the anatomical configuration of the unicornuate uterus, compromised functionality of the fallopian tubes, and obstacles to the translocation of the fertilized egg. The pathophysiological mechanisms relating unicornuate uterus and tubal dysfunction leading to ectopic implantation are not fully understood, but some possible explanations are: unicornuate uterus may markedly influence the structural and functional aspects of the fallopian tubes, predisposing them to incidents of occlusion, involuntary contraction, or aberrant wave-like motions. Such alterations can compromise the conveyance of the fertilized egg to the uterine sanctuary, culminating in its anomalous lodgment within the tubal membrane or atypical locales. Furthermore, the unicornuate uterus may exert a detrimental impact on the endometrium, the crucial uterine lining imperative for embryo adhesion and gestational sustenance. This condition is capable of inducing endometrial underdevelopment, inflammation, or deformation, thereby diminishing the endometrium's receptivity and viability. Consequently, this can obstruct the embryo's implantation within the uterine cavity or instigate its dislocation and relocation to the fallopian tubes or alternative ectopic sites. Diagnosing and treating this condition poses formidable challenges, demanding heightened vigilance and timely intervention to avert severe complications such as tubal rupture, profuse hemorrhage, infection, and infertility [6,7].

Presently, surgical interventions for IEP include laparoscopy and laparotomy [8]. In the wake of the progressions in laparoscopic surgical methodologies, its ubiquity in the management of interstitial ectopic pregnancies is demonstrably on the rise [9]. This article recounts a case of unicornuate uterus concomitant with IEP diagnosed through transvaginal ultrasound and delves into a comprehensive discussion regarding its diagnosis and treatment.

This article recounts a case of unicornuate uterus concomitant with IEP diagnosed through transvaginal ultrasound and delves into a comprehensive discussion regarding its diagnosis and treatment. Her transvaginal ultrasound revealed that the cystic mass protruded externally, connecting to the cornual region of the uterus, and the interstitial line sign [10] was evident. At the uterine fundus, there was a cystic mass measuring approximately 25 mm × 18 mm, containing a visible yolk sac, embryonic bud, and discernible primitive cardiac pulsations. Color Doppler Flow Imaging indicated blood flow signals within the cystic mass. We then progressed to 3D scanning, fine-tuning the sampling frame to encompass all pertinent structures. In this phase, data was gathered to form a 3D dataset. The system automatically compiled a sequence of 2D images, reconstructing them into a 3D volume. Observations were made on different planes such as transverse, sagittal, or coronal, which could be adjusted for optimal diagnostic perspectives. The 3D-TVUS revealed that the cystic mass protruded externally, connecting to the cornual region of the uterus, and the interstitial line sign was evident, and the 3D volumetric images displayed an endometrial coronal plane that resembled a “lancet”. The ultrasound findings suggested uterine developmental anomalies, with the sonographic image consistent with a presentation of a right-sided unicornuate uterus. A cystic mass at the uterine fundus, corresponding to an IEP, was identified.

Given the patient's desire for fertility, and following comprehensive informed consent, a laparoscopic procedure was performed. The patient was given general anesthesia and positioned in a bladder lithotomy position to move the intestines away from the pelvic area. A small incision was made near the navel and a trocar was inserted. Two more trocars were introduced through other minor incisions to facilitate the entry of other instruments. Carbon dioxide gas was pumped through the trocar to inflate the abdomen and create space for the laparoscope and other instruments. The laparoscope was inserted through the trocar and the surgeon inspects the pelvic organs and locates the IEP. In the course of the surgical procedure, it was discerned that the unicornuate uterus on the right side was in contiguous association with the right fallopian tube. A prominence of approximately 3 cm manifested within the inner segment of the right fallopian tube wall, situated exteriorly to the round ligament of the uterus. Notably, these anatomical features presented with an unbroken and intact surface, devoid of any discernible indications of rupture. No residual elements of the uterine body or fallopian tube were evident within the left pelvic cavity. The surgeon made an incision over the IEP and removed the pregnancy tissue. The surgeon used electrocautery devices to coagulate the bleeding vessels and suction devices to evacuate the blood and fluid. The surgeon closed the cornuostomy incision with interrupted sutures, removed the instruments and trocars, deflated the abdomen, and closes the skin incisions with stitches. The convalescence following the surgical intervention proceeded without complications.

3D ultrasound represents an advanced imaging modality that harnesses sound waves to forge three-dimensional representations of subjects, including fetuses, organs, or tissues. This technique affords a more intricate and lifelike visualization of anatomical structures and pathologies when contrasted with traditional 2D ultrasound methodologies [11]. A notable merit of 3D ultrasound is its capacity to reconstruct the coronal plane of the uterus, a perspective that proves challenging to achieve through 2D ultrasound. The coronal plane offers a transverse view of the uterus, elucidating the morphology and dimensions of the uterine cavity as well as the positioning of the endometrium [12]. 3D-TVUS is a widely accessible diagnostic tool that is commonly employed as the initial method for detecting uterine anomalies. Owing to its high diagnostic accuracy, 3D-TVUS has been suggested as a non-invasive “gold standard” technique for these malformations [13]. Additionally, 3D ultrasound introduces the capability for rendering reconstructions of the subject, employing surface or volume rendering to emulate the object's real-life appearance. Such rendering reconstructions significantly augment the perceptual depth and interpretative clarity of the 3D imagery, thereby facilitating enhanced communication and educational interactions among patients and healthcare professionals. The introduction of 3D-TVUS provides a more nuanced depiction of the extruding phenomenon of the gestational sac. This modality offers a volumetric display of the relationship between the endometrium and the gestational sac, playing a crucial role in the discriminative diagnosis of the two conditions. 3D-TVUS rectifies the limitations of 2D-TVUS in coronal imaging of the uterus.

Angular pregnancy, transpiring in the proximal aspect of the uterine horn adjacent to the uterine cavity, represents a form of intrauterine embryo implantation [14]. The close anatomical proximity of these two pregnancy types contributes to a heightened clinical misdiagnosis rate. Distinguishing between IEP and angular pregnancy has perennially posed challenges in ultrasonographic diagnosis. Key discriminative points in 3D-TVS diagnosis of IEP and angular pregnancy include: (1) the gestational sac in IEP is more conspicuously prominent beyond the contours of the uterine silhouette compared to the gestational sac in angular pregnancy; (2) the muscular layer surrounding the gestational sac in IEP is thinner and incomplete; (3) the gestational sac in IEP does not connect with the uterine cavity, whereas the uterine cavity in angular pregnancy is generally incomplete, and in IEP, the uterine cavity typically remains intact; (4) observation of the interstitial line sign [14].

Interstitial ectopic pregnancies are known for their diagnostic challenges and high-risk profiles, often leading to severe complications like rupture and hemorrhage [9,15]. The traditional 2D ultrasound often falls short in accurately diagnosing such complex cases, especially in anomalous uterine structures like a unicornuate uterus. This case report, therefore, underscores the diagnostic superiority of 3D-TVUS in such intricate scenarios. The "lancet-shaped" endometrial corona and the detailed visualization of the gestational sac near the uterus base, as revealed in the report, demonstrate the nuanced capabilities of 3D-TVUS. Such detailed imaging is crucial not only for diagnosis but also for precise surgical planning, which is vital in managing high-risk ectopic pregnancies.

Conservative methodologies encompass the administration of methotrexate (both local and systemic) and the employment of minimally invasive surgical interventions, which entail the resection of the affected fallopian tube and the embryo while ensuring the preservation of the uterine structure. Notwithstanding the emergence of these conservative approaches, the optimal modality for the management of interstitial ectopic pregnancies, as well as the care of patients in ensuing pregnancies, continues to be a subject of debate. Numerous scholars have documented the application of non-surgical interventions for the management of interstitia lectopic pregnancies identified via ultrasonography in the initial trimester [16-20]. The principal merit of such conservative treatment modalities lies in circumventing the formation of a surgical cicatrix on the uterus, along with mitigating the hazards intrinsic to operative procedures. However, the non-surgical approach is not without its perils, notably the risk of subsequent cornual rupture and the potential for life-threatening hemorrhage. Given these considerations, the pursuit of non-surgical therapy is advisable only under conditions where anesthesia and physicians possessing requisite surgical proficiency are accessible on a 24-hour basis.

Currently, the surgical management of interstitial ectopic pregnancies encompasses both laparoscopic and laparotomic interventions. With the advancements in laparoscopic surgical techniques, there has been a noticeable increase in the preference for laparoscopy in addressing interstitial ectopic pregnancies. This shift can be attributed to the minimally invasive nature of laparoscopic procedures, which offer significant benefits, including reduced postoperative discomfort, shorter hospital stays, and quicker recovery times. Laparoscopic cornual resection and cornuotomy as therapeutic modalities for interstitial gestation offer a refined scrutiny of minimally invasive surgical alternatives adapted to tackle this particular ectopic pregnancy site [21]. Laparoscopic cornual resection involves the precise excision of the affected segment of the uterus where the pregnancy has implanted outside the uterine cavity, specifically within the interstitial part of the fallopian tube. This method aims to completely remove the ectopic tissue while preserving the overall integrity and functionality of the uterus. Laparoscopic cornuotomy entails making an incision over the ectopic pregnancy site to extract the pregnancy tissue, followed by the repair of the uterine tissue. This approach is often considered when there is a desire to minimize uterine tissue removal, potentially preserving future fertility more effectively than with more extensive resection techniques.

Ultimately, the choice between laparoscopic cornual resection and cornuotomy for the treatment of IEP is contingent upon a multitude of factors, including the size and location of the ectopic pregnancy, the patient's hemodynamic stability, the surgeon's expertise, and the patient's reproductive desires. Within the confines of this report, considering the patient's expressly stated desire for the conservation of fertility, in conjunction with the diagnosis of interstitial ectopic pregnancies of a dimension less than 4 centimeters in diameter, a laparoscopic cornuotomy was executed with remarkable precision. This surgical intervention enabled the accurate extraction of the embryo ensnared within an IEP lesion, epitomizing the synthesis of sophisticated surgical prowess and a commitment to patient-centric reproductive health management. Even as, the quest to determine the safest methodology for addressing interstitial ectopic pregnancies and ensuring the well-being of patients in their ensuing pregnancies persists as a topic of considerable controversy, the core tenets of patient-centered treatment stand as a beacon of exemplary practice.

Some of the challenges or complications that may arise during or after the laparoscopic surgery are: (1) Difficulty in locating or accessing the IEP, especially if it is large, deep, or ruptured; (2) Excessive bleeding from the IEP or the cornuostomy incision, which may require blood transfusion or conversion to laparotomy (open surgery); (3) Injury to the surrounding organs, such as the bladder, bowel, ureter, or major blood vessels, which may require additional surgery or repair; (4) Infection of the surgical site or the pelvic cavity, which may require antibiotics or drainage; (5) Persistent or recurrent IEP, which may require further treatment with methotrexate (a medication that stops the growth of the pregnancy tissue) or repeat surgery; (6)Adhesion formation, which may cause pelvic pain, infertility, or bowel obstruction in the future.

The successful laparoscopic resolution, directed by 3D-TVUS identification of the gestational sac, underscores the efficacy of surgical management for ectopic pregnancies in anatomically unusual uterus. The ability to accurately locate the ectopic gestation minimizes surgical time and reduces the risk of complications, thereby enhancing patient safety and outcomes.

While this case report is illuminating, it also opens avenues for further research. Future studies could focus on comparing the outcomes of 3D-TVUS guided interventions in ectopic pregnancies with traditional methods, across various uterine anomalies. Moreover, there is a scope for technological advancements in 3D imaging to further refine resolution and accuracy, potentially integrating artificial intelligence for predictive analysis and decision-making support in complex ectopic pregnancies.

The present study has some limitations that need to be acknowledged. First, it is based on a single case, which limits the generalizability and the statistical significance of our findings. Second, the management of IEP is varied [8]. Therefore, more studies are needed to compare the outcomes and complications of different treatment options, such as medical therapy, conservative surgery, or radical surgery. Furthermore, it does not include long-term follow-up of the patient, which prevents us from evaluating the outcome of her future pregnancies and fertility. The risk of recurrence and adverse pregnancy outcomes should be evaluated in future research.

The case adds to the scarce literature on the coexistence of IEP and unicornuate uterus, a rare and challenging scenario that poses diagnostic and therapeutic dilemmas. Our case also supports the hypothesis that unicornuate uterus may be a risk factor for IEP, as it may alter the tubal anatomy and function, and impair the embryo transport. 3D-TVUS can be a useful tool for identifying the exact location and extent of IEP and unicornuate uterus, which can facilitate the planning and execution of the appropriate surgical intervention. Moreover, our case demonstrates that laparoscopic cornuostomy can be a safe and effective treatment option for IEP in unicornuate uterus, as it can preserve the uterus and the affected tube and reduce the risk of complications. As technology advances, so will our capacity to efficaciously diagnose and manage formidable conditions, ultimately enhancing patient welfare and results in reproductive medicine.

The authors declare that they have no conflict of interest.