Abdominal CSF pseudocyst
 Discussion of Abdominal CSF pseudocyst
- Peritoneal pseudocyst is a rare complication of ventriculoperitoneal shunt catheter placement.
- The time from the last shunting procedure to the development of an abdominal pseudocyst ranges from 3 weeks to 5 years.
- Cerebrospinal fluid pseudocysts are seen as a thin-walled cystic mass around the shunt tip. The wall is composed of fibrous tissue without an epithelial lining and is filled with cerebrospinal fluid. Debris is identified in the majority of the fluid collections.
- The pseudocyst can either move freely within the peritoneal cavity or adhere to small-bowel loops, the serosal surface of solid organs, the parietal peritoneum, or small-bowel loops. The latter would explain why some bowel loops may become engulfed when the pseudocyst increases in size or why the pseudocyst may be prone to torsion.
- Pediatric patients commonly present with symptoms of elevated intracranial pressure and abdominal pain, whereas adults predominantly present with abdominal signs only.
- Differential considerations include:
- It may be difficult to differentiate seroma, urinoma, abscess, lymphocele, and cerebrospinal fluid on the basis of imaging findings alone. Fine-needle aspiration with US or CT guidance has a high diagnostic yield.
- Excision or repositioning of the shunt tip with minimally invasive laparoscopic techniques is usually performed. This technique in the setting of a noninfected pseudocyst has proved to be safe, with results comparable to those of a conventional open surgical technique.
- If infection is present, the pseudocyst wall should be excised and the peritoneal shunt tube removed. Percutaneous drainage of the pseudocyst can be both diagnostic and therapeutic.
 Imaging Findings for Abdominal CSF pseudocyst
- Ultrasonography or CT can indicate the definitive diagnosis.
- US is the method of choice in the evaluation of the pseudocyst and other complications at the distal end of the ventriculoperitoneal shunt.
- Measurement of attenuation values with CT characterizes the contents as water attenuation and demonstrates the relationships of portions of the shunt catheter with the pseudocyst.
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 References for Abdominal CSF pseudocyst
- Juan Carlos Pernas, and Jordi Catala. Case 72: Pseudocyst around Ventriculoperitoneal Shunt. Radiology 2004 232: 239-243.