History
A 14-year-old 2.3-kg intact female domestic shorthair cat was brought to the National Chung Hsing University Veterinary Teaching Hospital, presenting with anorexia and gradual abdominal distension for 1 month. Notably, depression and a decreased amount of defecation were also noted by the owner.
Upon physical examination, the cat was quiet, alert, and responsive. Notably, marked abdominal distension, emaciation (body condition score 2/9) with severe muscle loss, and mild dehydration (approximately 5%) were observed. The vital signs were within the normal limits, and there were no abnormalities observed upon thoracic auscultation.
A CBC revealed marked leukocytosis (45.28 X 103 cells/µL; reference range, 2.89 to 17.02 X 103 cells/µL), characterized by neutrophilia (42.94 X 103 cells/µL; reference range, 2.3 to 10.29 X 103 cells/µL), monocytosis (1.17 X 103 cells/µL; reference range, 0.05 to 0.67 X 103 cells/µL), and eosinopenia (0.07 X 103 cells/µL; reference range, 0.17 to 1.5 X 103 cells/µL). Additionally, moderate thrombocytosis (873 X 103 cells/µL; reference ramge, 151 to 600 X 103 cells/µL) was observed. Serum biochemical analyses were observed to be within the normal limits. Two-view abdominal radiographic images were obtained (Figure 1).
Left lateral (A) and ventrodorsal (B) abdominal radiographic images of a 14-year-old 2.3-kg intact female domestic shorthair cat presented for anorexia and gradual abdominal distension for a month.
Citation: Journal of the American Veterinary Medical Association 262, 8; 10.2460/javma.24.04.0270
Diagnostic Findings and Interpretation
On abdominal radiography (Figure 2), serosal detail was absent, and a uniformly homogeneous soft tissue opacity was present throughout the markedly distended abdomen, indicating extensive peritoneal fluid. Only some intestinal loops filled with air or feces could be delineated. On the left lateral view, gas-filled small intestinal loops were displaced craniodorsally instead of being in the center of the abdomen; while on the ventrodorsal view, they were confined to the central region. The colon was dorsally displaced and filled with inspissated feces, consistent with constipation. As a result, there were 2 possible different diagnoses. First, there might be a space-occupying mass in the caudoventral abdomen, considering the female intact signalment, which might originate from the genital tract. Second, there might be severe adhesions preventing free movement of the intestinal loops, specifically, sclerosing encapsulating peritonitis. The other findings included protrusion of the spinous process resulting in an undulating cutaneous margin with a lack of subcutaneous and retroperitoneal fat, both suggesting emaciation and severe muscle loss in the patient, being consistent with the physical examination findings. An abdominal ultrasound was performed for further evaluation.
Radiographic images as shown in Figure 1. A homogeneous soft tissue opacity was distributed uniformly throughout the distended abdomen, causing markedly decreased detail and distended abdomen. The gas-filled small intestinal loops were displaced craniodorsally (arrow) and the descending colon was dorsally displaced (arrowheads). On the ventrodorsal projection, they were confined to the central region.
Citation: Journal of the American Veterinary Medical Association 262, 8; 10.2460/javma.24.04.0270
The abdominal ultrasound (Figure 3) revealed a large amount of echogenic peritoneal fluid was present throughout the abdomen. There was a large, markedly distended structure filled with echogenic fluids in the caudal abdomen, measuring up to 7.5 cm in thickness. The structure was divided into 3 rounded compartments. The caudal compartment was located between the urinary bladder and the descending colon, extending cranially and then separating into 2 symmetrical compartments. These compartments corresponded to the body of the uterus and the bilateral uterine horns; thus, the findings were indicative of pyometra, hydrometra, or mucometra. The pancreas was diffusely enlarged, irregularly shaped, and heterogeneous with some hyperechoic striations, which might suggest mineralization (Figure 3). Differential diagnoses of the pancreas were neoplasia, such as adenocarcinoma, or less likely pancreatitis. There were some hypoechoic nodules on the peritoneum, which might be suggestive of peritoneal metastasis. As a result, the central gathering of the small intestinal loops was due to a displacement of the bilaterally distended uterine horns, rather than the occurrence of severe adhesions. The remaining abdominal organs were unremarkable.
Abdominal ultrasonographic images of the cat. A—A large amount of peritoneal effusion can be observed (F). The bilateral uterine horns were distended and filled with echogenic fluids. B—The left pancreas between the stomach and spleen was irregularly enlarged and heterogeneous with some hyperechoic striations (arrowheads). F = Effusion. U = Uterine horns. SP = Spleen. ST = Stomach.
Citation: Journal of the American Veterinary Medical Association 262, 8; 10.2460/javma.24.04.0270
Treatment and Outcome
The abdominal effusion was aspirated and analyzed. The analysis result was exudate (total nucleated cell count, 6.96 X 103 cells/µL; total protein, 3.4 g/dL); additionally, there were no neoplastic cells. Thoracic radiography was performed for neoplasia staging and preoperative examination, and the result was unremarkable. An ovariohysterectomy and surgical biopsy of the pancreas were performed. During the surgery, the pancreas was observed to be grossly enlarged with an irregular shape, with numerous, disseminated, miliary nodules diffusely in the peritoneal surface, including the uterus. A small portion of the pancreas was excised for histopathological examination. The uterine body and bilateral uterine horns were rounded and markedly dilated, closely adhering to the adjacent urinary bladder and bilateral ureters (Figure 4). The exudate in the uterus was collected and Enterococcus sp was isolated. Notably, the excised uterus was sent for histopathological examination. The histopathological results of the pancreas and uterus determined the presence of adenocarcinoma, and the adenocarcinoma in the uterus was suspected to be metastatic. The patient died 3 days post-surgery.
Image during the surgery. The uterine body and bilateral uterine horns were rounded and markedly distended. There were numerous, disseminated, miliary, white nodules on the peritoneum (arrowheads). The pancreas was irregularly and markedly enlarged (P). P = Pancreas.
Citation: Journal of the American Veterinary Medical Association 262, 8; 10.2460/javma.24.04.0270
Comments
Radiographically, a distended abdomen, increased soft tissue opacity, and decreased serosal margin detail are suggestive of peritoneal effusion. Radiography is insensitive to the underlying causes of peritoneal effusion; therefore, abdominocentesis with fluid analysis and further imaging examinations are crucial diagnostic approaches to the underlying causes. The effusion can be generally classified into transudate, modified transudate, and exudate, depending on the total protein and nucleated cell count. In elderly cats, the most common cause of peritoneal effusion is neoplasia, followed by feline infectious peritonitis and heart diseases.1,2 Regarding peritoneal neoplastic effusion, the most common cause is carcinomatosis, which frequently originates from the liver and pancreas.2,3 Pyometra can be associated with peritoneal effusion1; a small amount of fluid appearing adjacent to the inflamed uterus seems reasonable, and a ruptured uterus can also result in septic effusion. However, based on the review of literature, such a large volume of peritoneal effusion in the present patient is considered unlikely to be caused by pyometra. In this patient, the cytology results of the peritoneal effusion revealed the absence of neoplastic cells, a possible finding in human and feline patients with carcinomatosis.2,3 Moreover, the hypoechoic nodules noted on the peritoneum were consistent with the previous description of sonographic findings for abdominal carcinomatosis3 and further confirmed by histopathology. Given the concurrent presence of the primary pancreatic adenocarcinoma, the peritoneal effusion was considered to be neoplastic peritoneal effusion.
In patients with a large volume of peritoneal effusion, the loss of serosal detail is generalized and significant; notably, only the structures filled with different opacities, such as gastrointestinal tracts can be visualized. The gas-filled segments of small intestine should float to the uppermost area due to buoyancy, thus on lateral views, the freely movable segments of intestinal loops will be in the central portion of the abdomen, unless also displaced by a mass lesion. In this case, the soft tissue mass was the uterus, which was markedly dilated. Therefore, if the gas-filled loops are not at the central area, a mass effect should be considered and requires further imaging examination.
Another possibility to cause the gas loops to not be centrally located is severe adhesions hindering the free movement of the intestinal loops. Thus, a rarely observed condition named sclerosing encapsulating peritonitis, which is defined as a chronic inflammatory disorder with the small intestines encased by a thick fibrotic membrane,4 should be put into the differential list. The radiographic characteristics are less specific, including abnormal intestinal gas distribution, abdominal distension, and homogeneous peripheral fluid opacity.4 Further imaging examinations are necessary to establish a definitive diagnosis, and an exploratory laparotomy with biopsy is essential for confirmation of the final diagnosis. The imaging findings of sclerosing encapsulating peritonitis include loculated peritoneal effusion, and encased, plicated, or corrugated intestinal loops observed on both CT and ultrasonography.4 Additionally, mesenteric fat stranding and an equivocal thickening with increased contrast enhancement of the peritoneum can be observed on CT.4
In conclusion, despite the fact that poor serosal detail caused by a large amount of peritoneal effusion impedes interpretation, the distribution of the small intestine can still provide useful information. In patients with an abnormal distribution of intestinal loops, a mass effect and sclerosing encapsulating peritonitis should be considered. Further imaging examinations and abdominocentesis with fluid analysis are essential to make a definitive diagnosis.
Acknowledgments
None reported.
Disclosures
The authors have nothing to disclose. No AI-assisted technologies were used in the generation of this manuscript.
Funding
The authors have nothing to disclose.
References
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Wright KN, Gompf RE, DeNovo RC Jr. Peritoneal effusion in cats: 65 cases (1981-1997). J Am Vet Med Assoc. 1999;214(3):375-381. doi:10.2460/javma.1999.214.03.375
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Monteiro CB, O’Brien RT. A retrospective study on the sonographic findings of abdominal carcinomatosis in 14 cats. Vet Radiol Ultrasound. 2004;45(6):559-564. doi:10.1111/j.1740-8261.2004.04096.x
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Gremillet BCH, Porsmoguer C, Bolen G, et al. Imaging findings in dogs and cats with presumptive sclerosing encapsulating peritonitis. Front Vet Sci. 2022:9:891492. doi:10.3389/fvets.2022.891492
