Intussusception in adult patients is relatively rare, representing only 5% of all cases of intussusception and less than 5% of all cases of bowel obstruction . Incidence in the adult versus the pediatric population differs in both etiology and management. Whereas pediatric cases are predominantly benign and managed non-operatively with hydrostatic reduction, adult intussusception is the result of a malignant lead point in approximately 65% of cases  mandating surgical management.
Anatomic locations of intussusception include entero-enteric, colo-colic, and ileo-colic, and the differential diagnosis for the underlying etiology can be made upon location alone. Small bowel intussusception can be due to adhesions, Meckel's diverticulum, inflammatory bowel disease, lymphoma, primary malignancy or metastatic disease, as opposed to large bowel intussusception, which is due to an underlying malignancy in the majority of cases.
Clinical presentation of adult intussusception is typically significant for signs and symptoms of bowel obstruction. The diagnosis is radiologic, with imaging modalities that can be diagnostic or ancillary including plain radiographs, ultrasound, computed tomography scan, and endoscopy. Surgical management of adult intussusception is mandatory, with specific operative intervention tailored to anatomic location and etiology. If the diagnosis of a benign etiology is definitive, distal to proximal reduction can be safely performed followed by limited resection with primary anastamosis . However, when the etiology is unknown or when the presence of malignancy is unequivocal, a formal oncological resection should be performed. This may include a primary anastamosis or stoma formation depending on location, bowel wall integrity, degree of contamination, and surgeon preference.
Although bladder cancers can disseminate hematogenously or lymphatically, superficial tumors (T1) rarely metastasize. When metastatic disease is present, it is most frequently in the pelvic lymph nodes, liver, lungs, or bone , with no reported cases of superficial local disease metastasizing to the gastrointestinal tract to date. Even muscle-invading cancers (≥T2), which metastasize more frequently, rarely spread to bowel, accounting for only 13% of all sites of metastatic disease from both transitional cell and squamous cell carcinomas .
Transitional cell carcinomas of the genitourinary tract with sarcomatoid differentiation are extremely rare, representing tumors with both epithelial and non-epithelial components. Although debate exists as to the pathogenesis and nomenclature of such tumors,  they tend to be more aggressive with a higher incidence of malignancy. Perhaps the natural history of this subtype of transitional cell carcinoma contributed to our patient's unique presentation and pattern of metastasis despite only local invasion of the bladder urothelium.