Primary splenic pregnancy: a case report.

A 24-year-old Han Chinese female patient was admitted to the hospital with 59 days of amenorrhea with left lower abdominal pain for 12 days. The patient had regular menstruation in the past and presented with a small amount of vaginal bleeding 2 weeks ago without fever, diarrhea, nausea, or vomiting. She underwent tubal recanalization 1 year prior for “bilateral tubal obstruction.” The patient underwent gynecological ultrasound, which showed no gestational sacs in the uterine cavity or bilateral adnexal areas; serum beta human chorionic gonadotropin (β-HCG) level was 20,447 IU/L, leading to consideration of ectopic pregnancy. Physical examination: The patient’s entire abdomen was soft, with pressure pain in the left lower abdomen without rebound pain; liver and spleen were not palpable; and no shifting dullness was detected. A follow-up gynecological ultrasound 3 days after admission showed no gestational sacs in the uterine cavity or bilateral adnexal areas; serum β-HCG level was 37,383 IU/L. Abdominal ultrasound was performed to show a hypoechoic area in the spleen, measuring about 1.7 cm × 1.5 cm, within which no obvious blood flow signal was seen, and a splenic cyst was considered; a plain computed tomography (CT) of the abdomen showed an intra-splenic cystic foci with well-defined borders, approximately 1.4 cm in length and longitude, and a mean attenuation of 8 Hounsfield units (HU), consistent with fluid. Considering that the gestational sac was not detected by repeated ultrasound and CT examinations, the patient was subjected to laparoscopic exploration and curettage during which repeated laparoscopic exploration of the abdominal wall, uterus, bilateral fallopian tubes and ovaries, the pouch of Douglas, the surface of the intestinal canal, the greater omentum, and the liver and spleen did not reveal any obvious lesions; pathology showed endometrial changes in the secretory phase. Ultrasound of the upper abdomen was repeated 6 days after admission, which showed an irregular slightly hypoechoic mass of about 4.3 cm × 3.7 cm in size in the spleen, with poorly defined borders, within which a patchy anechoic area and an embryo were seen, with primitive cardiac ductal pulsations vaguely visible. In addition, stripes of hematogenous signals were seen around the lesion (Fig.  1 ). A plain CT scan of the entire abdomen showed a swollen spleen with a slight localized hypodensity, measuring about 4.0 cm × 3.9 cm, within which a more hypodense focus was seen, with an irregular morphology, and nodular soft tissue density shadows were seen at the edges (Fig.  2 ); serum β-HCG level of 66,369 IU/L did not show a significant decrease. In summary, the diagnosis was ectopic pregnancy with splenic implantation (Table  1 ). Fig. 1 a A two-dimensional abdominal ultrasound showing a hyperechoic (arrow) area within the spleen, with a patchy echo-less area seen within it; b striated blood flow signals seen within the lesion Fig. 2 Computed tomography scan of the abdomen, transverse view of mixed-density foci within the spleen (arrow), with areas of lower density within them and soft tissue density shadows at the margins Table 1 Patient management history Timeline Inspection 28 March 2022 Ultrasound examination: It revealed no gestational sac in the uterine cavity or bilateral adnexal regions Serum β-HCG 20,447 IU/L 31 March 2022 Ultrasound examination: It revealed no gestational sac in the uterine cavity or bilateral adnexal regions. A hypoechoic area measuring about 1.7 cm × 1.5 cm was identified in the spleen. Given the absence of internal blood flow signals, a splenic cyst was considered CT: A well-defined intra-splenic cystic lesion was identified, measuring approximately 1.4 cm in maximal diameter and demonstrating a mean attenuation of 8 Hounsfield units (HU), consistent with fluid Serum β-HCG 37,383 IU/L 1 April 2022 Laparoscopic exploration and curettage: It did not reveal any obvious lesions 3 April 2022 Ultrasound examination: An irregular, slightly hypoechoic mass (approximately 4.3 cm × 3.7 cm) with poorly defined borders was identified in the spleen. Within it, a patchy anechoic area and an embryo were visualized, with primitive cardiac ductal pulsations vaguely discernible. Color Doppler examination revealed strips of hematogenous signals surrounding the lesion CT: It revealed swollen spleen with a slight localized hypodensity, measuring about 4.0 cm × 3.9 cm, within which a more hypodense focus was seen, with an irregular morphology, and nodular soft tissue density shadows were seen at the edges Serum β-HCG 66,369 IU/L a A two-dimensional abdominal ultrasound showing a hyperechoic (arrow) area within the spleen, with a patchy echo-less area seen within it; b striated blood flow signals seen within the lesion Computed tomography scan of the abdomen, transverse view of mixed-density foci within the spleen (arrow), with areas of lower density within them and soft tissue density shadows at the margins Patient management history Ultrasound examination: It revealed no gestational sac in the uterine cavity or bilateral adnexal regions Serum β-HCG 20,447 IU/L Ultrasound examination: It revealed no gestational sac in the uterine cavity or bilateral adnexal regions. A hypoechoic area measuring about 1.7 cm × 1.5 cm was identified in the spleen. Given the absence of internal blood flow signals, a splenic cyst was considered CT: A well-defined intra-splenic cystic lesion was identified, measuring approximately 1.4 cm in maximal diameter and demonstrating a mean attenuation of 8 Hounsfield units (HU), consistent with fluid Serum β-HCG 37,383 IU/L Ultrasound examination: An irregular, slightly hypoechoic mass (approximately 4.3 cm × 3.7 cm) with poorly defined borders was identified in the spleen. Within it, a patchy anechoic area and an embryo were visualized, with primitive cardiac ductal pulsations vaguely discernible. Color Doppler examination revealed strips of hematogenous signals surrounding the lesion CT: It revealed swollen spleen with a slight localized hypodensity, measuring about 4.0 cm × 3.9 cm, within which a more hypodense focus was seen, with an irregular morphology, and nodular soft tissue density shadows were seen at the edges Serum β-HCG 66,369 IU/L Immediate laparoscopic total splenectomy was performed, during which a ventral protrusion of approximately 5 cm in diameter above the splenic hilum was seen, with localized scattered ecchymosis. The incision of the lesion and the presence of the gestational sac and embryonic tissue within it, with scattered petechial hemorrhages in the surrounding splenic parenchyma, were considered to be a splenic pregnancy. Pathohistological examination confirmed a splenic pregnancy (Fig.  3 ). There was an intraoperative blood loss of approximately 20 mL. Postoperatively, the patient received supportive care, including gastric protection, antibiotics, antispasmodics, analgesics, and fluid therapy. Subsequently, 1 week after surgery, her serum β-HCG level had decreased to 59.27 IU/L. She recovered without complications and was discharged. Fig. 3 Histopathology showing normal splenic structures, blood clots, and placental villi (arrow); hematoxylin and eosin 200× Histopathology showing normal splenic structures, blood clots, and placental villi (arrow); hematoxylin and eosin 200×

Ectopic pregnancy refers to a fertilized egg planted outside the endometrium within the uterus. It accounts for 1–2% of all pregnancies, with tubal pregnancies being the most common type. Pregnancies in the peritoneum, mesentery, greater omentum, uterine horns, ovaries, broad ligaments, diaphragm, and liver and spleen are less common [ 1 – 3 ]. Splenic pregnancies are classified as primary and secondary. Primary splenic pregnancy refers to the implantation of a fertilized egg directly on the surface of the spleen [ 4 ]; secondary splenic pregnancies often occur after rupture of tubal pregnancies but can also be secondary to ovarian or uterine pregnancies with uterine scarring and peritoneal fistulae [ 3 ]. The diagnostic criteria for primary abdominal pregnancy proposed by Studdiford [ 5 ] include: (1) normal fallopian tubes and ovaries; (2) absence of uteroperitoneal fistula; (3) the pregnancy is associated only with the abdominal cavity, and there is no possibility of tubal pregnancy. Our patient met all the above diagnostic criteria for a primary splenic pregnancy. Owing to the rich blood supply and fragile texture of the spleen, splenic pregnancy is highly susceptible to rupture and hemorrhage and can even endanger the patient’s life [ 6 ]. This article reports the diagnosis and management of a primary splenic pregnancy to increase clinicians’ knowledge of this disease.

We report a patient with an accurate preoperative diagnosis of splenic pregnancy, emphasizing the importance of imaging. In the clinical workup of women of childbearing age who have stopped menstruating, the locus of ectopic pregnancy should take into account the possibility of the spleen, and the scope of the ultrasound scan or CT/MRI scan should include the entire abdomen. In addition, dynamic ultrasound sweeps can be performed, which can improve diagnostic accuracy to some extent.

Abdominal pregnancies account for 1.3% of all ectopic pregnancies [ 7 ]. Primary splenic pregnancy is one of the rarest types of abdominal pregnancy, and the spleen provides conditions for implantation of the fertilized egg owing to its flat surface and rich blood supply, but the exact mechanism of occurrence is unknown [ 8 ]. The mechanism of splenic pregnancy reported in the literature [ 6 ] may be the retrograde peristalsis of the fallopian tubes draining the fertilized egg into the peritoneal cavity and implantation of the fertilized egg into the spleen by strong intestinal peristalsis before it is absorbed into the peritoneum. In addition, the presence of splenogonadal fusion sign suggests that the spleen has a suitable environment for implantation of fertilized eggs. The splenic and gonadal primordia are formed almost simultaneously before gonadal descent at 5–8 weeks of gestation. The caudal migration of the splenic primordium, located dorsal to the rotating midgut, can lead to an anomalous fusion of these two primordial structures. [ 9 , 10 ]. History of tubal and pelvic surgery, previous ectopic pregnancy, oral contraceptives, endometriosis, assisted reproductive technology, and inflammation of the fallopian tubes and pelvis are risk factors for the development of abdominal pregnancy [ 7 ]. Our patient had undergone tubal recanalization for “bilateral tubal obstruction,” which may have resulted in damage to the tubal cilia and abnormal peristaltic function, increasing the risk of splenic pregnancy. The spleen’s rich blood supply and its inability to accommodate placental attachment and embryonic growth make splenic pregnancies more susceptible to early rupture and hemorrhage and have a significantly higher mortality rate than other types of ectopic pregnancies [ 11 ]. Early diagnosis of splenic pregnancy is extremely important, but the lack of specific clinical manifestations and signs of splenic pregnancy makes diagnosis difficult. Current criteria for diagnosing ectopic pregnancy include ultrasonography and serum β-human chorionic gonadotropin monitoring [ 12 ]. In general, serum β-human chorionic gonadotropin levels are significantly higher than normal in patients with ectopic pregnancies but lower than in intrauterine pregnancies of the same gestational age [ 13 ]. Ultrasound of splenic pregnancy showed a slightly hyperechoic mass in the spleen with a patchy echogenic area, partially detectable germ, and primitive cardiac tube pulsation. In addition, a small blood flow signal was seen around the gestational sac. CT showed irregular low-density foci in the spleen; nodular soft-tissue density shadows were seen at the edge of the gestational sac (as seen in some patients); and the foci showed marked inhomogeneous enhancement. Moreover, thickened vascular shadows were seen within them [ 14 ]. When the gestational sac ruptured, active hemorrhage was seen in the periphery, as evidenced by linear contrast extravasation and perisplenic accumulation of blood [ 15 ]. MRI showed a thick-walled, long T1 mixed with long T2 cyst-like structure in the spleen with no signal reduction in the antiphase. In addition, some lesions may be associated with subperitoneal hematomas [ 16 ]. Early splenic pregnancy is highly susceptible to misdiagnosis due to atypical imaging, and dynamic ultrasound scanning and MRI scanning can help to differentiate them and improve diagnostic accuracy. In this case, the patient was misdiagnosed with a splenic cyst in the early stages, but as the gestational sac developed, abdominal ultrasound revealed the germ and primitive cardiac ductal pulsations within the lesion, which led to a diagnosis of a splenic pregnancy. Laparoscopy is both diagnostic and therapeutic, making it the optimal choice for diagnosing splenic pregnancy. Laparoscopic exploration is performed when necessary in patients who can not be clearly diagnosed. In this case, the gestational sac was in a deeper position, and no lesion was found during laparoscopic exploration; therefore, when the gestational sac is not easily detected by deeper exploration, additional puncture points may be appropriate to facilitate a more comprehensive exploration. Ruptured splenic pregnancy with hemorrhage can be life-threatening, so early detection and prompt treatment of pregnancy lesions can reduce mortality in splenic pregnancies. Splenectomy remains the mainstay of treatment for splenic pregnancies; preoperative embolization of the splenic artery reduces intraoperative hemorrhage and decreases the risk of rupture of the gestational sac. Moreover, local debridement of the lesion is feasible when the gestational sac is located on the surface of the spleen [ 7 , 17 ]. However, in patients with hemorrhagic shock, emergency open surgery should be performed. Klang [ 14 ] and others have reported a case of fetal death induced by ultrasound-guided injection of an appropriate amount of potassium chloride into the gestational sac; however, this carries the risk of causing maternal cardiac arrest. Therefore, different treatment options should be chosen depending on the patient’s specific situation.