Fallopian tube deciduosis with massive hemoperitoneum in a second-trimester pregnancy: a case report of ultrasound findings

Deciduosis is a decidual reaction outside the uterus that typically occurs during pregnancy. It is usually asymptomatic, but several life-threatening complications have been reported. Imaging features of this condition are lacking. This case report describes the ultrasound and clinical findings in a pathologically confirmed case of deciduosis. A 28-year-old primigravida with 23 weeks of gestation was referred to our department with severe abdominal pain. Pelvic ultrasound showed a left-sided, oval, well-circumscribed, solid, heterogeneous, predominantly hypoechoic pelvic mass without vascularity. There was abundant free fluid in the perihepatic and perisplenic spaces. The patient went into hypovolemic shock, leading to emergency surgery. Active bleeding from the left fallopian tube and a large hemoperitoneum of 1500 ml were found in this area and evacuated. A congestive fallopian tube with an arborescent zone and bleeding near the fimbria was removed. The histopathological features of the left salpingeal mass were consistent with decidual tissue surrounded by a hematoma. This case report is the first in Mexico to emphasize the imaging findings of this entity. It is presented as an educational tool that highlights deciduo - sis as a potential differential diagnosis in the emergency abdominopelvic ultrasound of pregnant patients.

Decidua. Fallopian tube. Pregnancy complications. Ultrasonography. Hemoperitoneum. Case report.

Deciduosis is the presence of an ectopic decidual reaction outside the uterus. It consists of a metaplastic change in submesothelial mesenchymal cells 1 induced by progesterone or progesterone-like substances released by the corpus luteum or adrenal cortex 2,3. Deciduosis has been reported at gynecological, gas - trointestinal, renal, lymph node, diaphragmatic, surgical scar, and omentum sites2,4,5. The etiology of deciduosis is unclear, and there are two main theories. One is that decidual cells are already outside the uterus, and the other is that the superficial coelomic stroma undergoes metaplasia. The latter is the most widely accepted 3,5,6. Although deciduosis was first described by Walker von Solothurn in 18645, knowledge of the imaging features, particularly ultrasonography, is limited. The available lit - erature provides no specific information, with reported ultrasound findings related primarily to free fluid detec - tion (usually without debris) or bowel distension, partic - ularly in the context of reactive ileus or bowel obstruction due to complications1. There are no ultrasound diagnos- tic or prognostic criteria, and histopathological examina- tion remains the gold standard for diagnosis 5. Although deciduosis is usually asymptomatic, its clinical manifestations may include abdominal pain, obstructive ileus 2,4, hematuria 2, recurrent pneumotho - rax, obstructed labor, or hemoperitoneum 7. The main D. Camorlinga-Ornelas, D. Garza-Cruz. Deciduosis with hemoperitoneum in pregnancy 129 contribution of imaging in abdominal pain is to rule out other causes of acute abdomen 8. No specific findings for deciduosis have been described by any imaging method, implying that it could be dismissed due to its similar density to the surrounding tissues 8. This case report describes the clinical and ultrasound findings in a 28-year-old primigravida with 23 weeks of gesta - tion, severe abdominal pain, and a pathologically con - firmed diagnosis of deciduosis. CASE DESCRIPTION Our patient was a 28-year-old Caucasian female, gravida 1, para 0, with 23 weeks of pregnancy, referred to the imaging department because of diffuse abdomi - nal pain radiated to the anal region and persistent nau - sea and vomiting. Before this event, her pregnancy had been carefully screened and was uneventful. Physical examination revealed pallor, drowsiness, stable cardio - pulmonary function, a distended abdomen secondary to pregnancy, and generalized abdominal pain with ten - derness, guarding, and a positive rebound sign. Vital signs and laboratory values were normal. She was ini - tially treated with indomethacin for early preterm labor with a poor response. An ultrasound was requested. Imaging findings Abdominopelvic and obstetric ultrasounds were per - formed with an ACUSON Sequoia VA25 SW Ultrasound System (Siemens Medical Solutions, Inc., Mountain View, CA, USA) with a 5-MHz curved transducer. The obstetric ultrasound showed no significant abnormalities (Figure 1). The upper abdominal examination revealed no abnormal findings in the solid organs. Pelvic ultra - sound showed a left-sided, oval, well-circumscribed, solid, heterogeneous, predominantly hypoechoic pel - vic mass with no vascularity detected on color Doppler examination. Abundant free fluid was noted in the perihepatic and perisplenic spaces and the right lower quadrant ( Figures 2 and 3). Clinical course The patient eventually presented hypovolemic shock, and an emergency laparotomy was performed. During the procedure, a hemoperitoneum of 1500 ml was evacuated. Active bleeding from the left fallopian tube and a large hematoma were observed; therefore, a left salpingectomy was performed, and hemostasis was achieved. An emer- gency cesarean section was not required. An arborescent zone and a bleeding area near the fimbria were found on the excised congested fallopian tube. The patient was discharged with an ongoing pregnancy. A B Figure 1. Ultrasound examination of the fetus at 23 weeks gestation. A: the fetal heart rate is normal, and the fetus is in a cephalic position. B: color Doppler duplex ultrasound image along the umbilical cord showing a typical flow pattern with a pulsatility index in the 46 th percentile for gestational age (normal). Figure 2. Longitudinal ultrasound of the right upper quadrant of the abdomen in a pregnant 28-year-old female shows abundant free fluid around the liver. J Mex Fed Radiol iMaging . 2024;3(2):128-131 130 Histopathological findings The wall and mucosa of the left fallopian tube were undamaged and showed typical histological characteristics. Tissue with a decidual appearance was found on the serosa with extensive areas of fresh hemorrhage alter - nating with lakes of erythrocytes, fibrin, and polymorpho- nuclear debris in a diffuse distribution. These findings were consistent with focal peritoneal deciduosis with hemorrhage and acute inflammation ( Figure 4).

We present the case of a 28-year-old primigravida diagnosed with hemorrhagic salpingeal deciduosis with ultrasound findings of a left, oval, well-circumscribed, predominantly hypoechoic pelvic mass in the left fallo - pian tube, attributed to a large hematoma with active bleeding and typical histological characteristics. This is the first case report from Mexico of deciduosis localized in the fallopian tube, which is presented for educational purposes to highlight the importance of ultrasound examination. We found that information on ultrasound findings in deciduosis is lacking in the literature. In four cases doc - umented by Chai et al. 9, three underwent ultrasound examination. Two of these had a nondiagnostic ultraso - nography, while the third had a nonspecific mass and free fluid. These findings suggest that ultrasound is of limited use in diagnosing deciduosis or there is a lack of knowledge on the subject. A case report by Jeong et al.10 described an ovarian mass with a heterogeneous cystic pattern, solid components, and vascularization on Doppler examination. These findings were similar to those of ours. Furthermore, Wong et al.11 documented a case of intracystic vegetations in ovarian deciduosis that appeared as a multilocular mass with nodular thickening of its septa and internal vascularization, which are features not identified in our case. Deciduosis is usually avascular on Doppler exam - ination, although it may show some vascularity, as mentioned in previous cases. Complications can be accompanied by free fluid, especially in case of hemo - peritoneum. No additional features, such as calcifications, acoustic shadowing, or lymphadenopathy, have been reported. The reported cases demonstrate the wide vari- ety of findings associated with deciduosis and emphasize the importance of a comprehensive imaging study. Although specific imaging findings in deciduosis remain elusive, available reports indicate a wide spectrum in size, border definition, sonographic pattern, Figure 3. Longitudinal ultrasound of the left flank in a pregnant 28-year- old female shows a left mass adjacent to the uterus (arrowhead). It is oval and well-circumscribed with a predominantly hypoechoic hetero- geneous pattern. Color Doppler examination showed no flow (data not shown). A B Figure 4. A: a microscopic examination of the resected tissue shows several foci of atypical decidual reaction consisting of a cluster of polygonal cells with abundant homogeneous eosinophilic cytoplasm, large nuclei, and some areas of vacuolar degeneration. No cellular atypia or mitotic areas were detected; hematoxylin and eosin stain 40×. B: the adjacent blood vessels are damaged (arrowhead); hema - toxylin and eosin stain 10×. D. Camorlinga-Ornelas, D. Garza-Cruz. Deciduosis with hemoperitoneum in pregnancy 131 echogenicity, and inner characteristics. Our imaging findings are consistent with the literature and showing nonspecific mass features. Some authors report multiple nodules at different sites 6,7. They can be isolated or coalescent6 and tend to be millimeter-sized nodules but they also occur as large masses6 appearing as predom- inantly cystic and well-circumscribed lesions with vascu- larity6,7. There is one documented case of a large intrauterine mass consisting of an ectopic decidua with high internal vascularity on Doppler (known as a decid - uoma)6. We infer a wide spectrum of findings and decid- uosis may present as a single or multiple solid masses12, localized at any site with submesothelial mesenchymal cells1, including the salpinges, as in our case. The symptoms of deciduosis are non-specific and they mimic other pathologies. Although the clinical course is usually benign, complications such as massive hemo - peritoneum can occur, compromising maternal and fetal life. In some cases, emergency surgery may be required. Macroscopically, they appear as whitish-yellow nodules with or without hemorrhagic areas that can be mistaken for carcinomatosis 2. The final diagnosis of deciduosis was confirmed by immunohistopathology after surgery in all the reported cases. This tissue must be differ - entiated from the decidual variant of mesothelioma, metastatic malignant melanoma 7, carcinomatosis, and granulomas1,8. The main limitation of this report is the lack of immunochemical correlation.

The possibility of deciduosis should be considered for pregnant women with acute abdominal pain and free fluid, especially when other causes of spontaneous hemoperitoneum have been ruled out. A complementary study of the imaging findings with detailed ultrasound descriptions is crucial to increasing our knowledge of this topic. Therefore, this case report serves as a valu - able basis for discussion and future research. Acknowledgments The authors thank Alexis Zúñiga, MD, Radiologist in Hospital Angeles Torreon, for his help in obtaining repre- sentative ultrasound images, and Luis Vitiénez, MD, Department of Pathology, Hospital Angeles Torreon, for his support with pathological data. They also extend their sincere thanks to Professor Ana M. Contreras-Navarro for her guidance in preparing and writing this scientific paper. Funding This research received no external funding. Conflicts of interest The authors declare no conflicts of interest. Ethical disclosures Protection of human and animal subjects. The procedures of this case report were conducted in agreement with the Declaration of Helsinki (1964) and its amendments. Confidentiality of data. The authors followed the pro- tocols of their work center for the publication of patient data. Right to privacy and informed consent. Informed consent was not required for this case report of rou - tinely collected clinical data. Use of artificial intelligence. The authors did not use generative artificial intelligence to prepare this manuscript or create figures or figure legends.

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