Small bowel intussusception in an adult with giardiasis
A previously healthy 31-year-old male presented to the Emergency Department with 3 weeks of nausea, vomiting, and watery blood-tinged diarrhea after drinking well water from his worksite where he worked as a logger. The patient had been seen for similar symptoms at another hospital 2 weeks prior, for which he was treated symptomatically with antiemetics. Physical exam was significant for tachycardia to 105 bpm, temperature of 37.9 C, and left abdominal tenderness without guarding or rigidity. Laboratory evaluation was significant for a mild leukocytosis to 11.1 cells/uL without left shift. Liver function tests, chemistries including lipase, and urinalysis were unremarkable.
Contrast enhanced abdominopelvic CT was performed which demonstrated moderate smooth and circumferential wall thickening of the proximal jejunum with two foci of intussusception without definite focal lead point or mass (Figures 1, 2). Outside medical records were requested, which were significant for positive giardia-specific stool antigen. The patient was treated with intravenous fluids and Metronidazole with improved symptoms the following day. Follow-up abdominopelvic CT one day after treatment and initial imaging demonstrated moderate persistent proximal jejunal wall thickening with resolution of the intussusception (Figure 3).
Although most cases of colonic intussusception are associated with lead points, it is not the case with small bowel intussusception. Although small bowel intussusception may occur with lead points such as lipomas, polyps, metastases, adenocarcinoma, and postoperative adhesions, at least half the time small bowel intussusception occurs without an identifiable lead point. The mechanism of intussusception without a lead point is not well understood. One proposed theory is that any inflammatory pattern or bowel irritant can have a traction effect during peristalsis. As there is no associated mechanical lesion, however, these types of intussusception tend to be transient and are less likely to cause proximal bowel obstruction. Chronic inflammatory bowel conditions, such as Crohn’s disease or celiac disease, are potential inflammatory causes of intussusception with a proposed mechanism of bowel wall atrophy and distension causing disorganized peristalsis. The imaging findings of intussusception have been well characterized. On CT, as seen in the presented case, typical findings include the “target-sign” or a “sausage-shaped mass,” analogous to the “target” or “doughnut” appearance on ultrasound. Additionally, the causative lead point may be seen on CT, which was not identified in the presented case. On upper GI studies, intussusception can appear as the classic “stack of coins” morphology. Treatment of intussusception is somewhat controversial and has undergone significant modifications over the last several decades. In early surgical literature, non-transient adult small and large bowel intussusception was treated surgically due to the risk of underlying malignancy. However, recent evidence suggests that up to 84% of small bowel intussusception of any cause may be self-limited. The location of the intussusception should also be considered, as distal small bowel intussusception is more likely to progress anterograde to involve the colon, which may alter management. This case report serves to add giardiasis to the differential of potential causes of transient small bowel intussusception in adults, the knowledge of which may facilitate the diagnosis and curative management.
- Colonic intussusceptions are often associated with lead points, while small bowel intussusceptions less commonly occur with an identifiable lead point. - Typical imaging findings of intussusceptions on CT include the "target sign" and a "sausage shaped mass". - Most small bowel intusussuceptions are treated conservatively with spontaneous resolution. - Infection should be considered as a possible etiology of small bowel intussusceptions.