This case was presented in one of our monthly virtual Abdominal Rounds with Donald E. Thrall DVM, PhD, DACVR in 2021. If you’d like to join us in these virtual sessions. please click this link.
History: Vomiting and diarrhea for 24 hours. Diarrhea has become hemorrhagic. The patient has a history of eating things. Parvo snap test was negative. The patient is dehydrated.
Imaging: Survey radiographs of the abdomen were made. There was some material in the stomach but no evidence of obstruction. There were no other abnormalities. In follow-up radiographs of the abdomen made 24 hours later, there was some concern for a distended loop of intestine in the central abdomen but the significance of this was not clear. Either ultrasound evaluation of the abdomen or a barium study was recommended.
The practice did not have access to ultrasound so a barium study was elected. In the first few images made following barium administration, there were no abnormalities detected. One final set of radiographs was acquired (Figure 1).
Figures 1A, B. Lateral and ventrodorsal views of the abdomen were acquired approximately 3 hours after oral administration of barium.
Before enumerating the findings, the anatomy and terminology of an intussusception must be understood (Figure 2).
Intussusceptum: The part of the bowel that is invaginated within another part of an intussusception. The direction of travel, or telescoping, is from orad to aborad.
Intussuscipiens: The part of the bowel into which another part is invaginated in an intussusception.
Findings (Fig 3A, B):
- Most of the barium is within the colon.
- In both of the images there is a thin tubular accumulation of barium in the central portion of the ascending colon (solid arrows) surrounded by a hazy filling defect.
- At the aborad end of the tubular accumulation of barium is a more defined, round, filling defect (dashed arrows).
- The ileocolic junction and cecum are displaced to the left of midline rather than in their normal right-sided location.
- The findings are indicative of an ileocolic intussusception
- The thin tubular accumulation of barium is created by the presence of barium in the lumen of the intussusceptum.
- The round filling defect at the aborad end of the tubular accumulation of barium is created by the tip of the intussusceptum surrounded by barium.
There are numerous causes of ileocolic intussusception, including parasitism, linear foreign body, enteritis and intestinal masses (Wilson & Burt, 1974). In many patients, the intussusception is idiopathic. In theory, anything that stimulates intestinal contraction can result in an ileocolic intussusception. Most patients developing an intussusception are young. In one study, the mean age of 27 dogs diagnosed with an intussusception was 11.9 mo. (Levitt & Bauer, 1992). It is a misconception that ileocolic intussusception results in a complete intestinal obstruction; many patients have chronic signs due to the obstruction being partial. In the case above, the partial nature of the obstruction is proven by the presence of barium in the lumen of the intussusceptum, and barium entering the more distal aspects of the colon. Common clinical signs related directly to the presence of an intussusception are vomiting (23/27 dogs), diarrhea (20/27 dogs) and a palpable abdominal mass (16/27 dogs) (Levitt & Bauer, 1992).
In some patients, an intussusception can be diagnosed from survey radiographs by finding gas outlining the leading edge of the intussusceptum. This appearance has been described using various terms, including bullet sign and meniscus sign. The ultrasonographic appearance of an intussusceptum has been thoroughly described and ultrasound is highly sensitive and specific for diagnosing this condition (Lamb & Mantis, 1998) (Patsikas, et al., 2003). Therefore, few patients need other modalities for confirmation of an intussusception. However, in some there will not be supporting evidence of an intussusception in survey radiographs and ultrasound will not be available, as in the case presented here. In that instance, an upper gastrointestinal barium study can be of use. A barium enema would also be appropriate if the index of suspicion of an intussusception was high.
The key signs to look for in an upper GI study in a patient with an ileocolic intussusception were present in this case. These include barium in the lumen of the intussusceptum, a filling defect in the intussuscipiens created by barium surrounding the intussusceptum, and a focal filling defect created by barium surrounding the leading edge of the intussusceptum.
In a more chronic, or a more obstructive, intussusception, the intussusceptum can become edematous. Or, mesenteric fat can be pulled into the intussuscipiens along with the intussusceptum. This can increase the level of obstruction that is present and prevent barium from being present in the lumen of the intussusceptum. Also, as the intussusceptum becomes more edematous, it creates a more obvious filling defect with a concentric appearance that has been referred to as the coiled-spring appearance (Levine, Trenkner, Hwerlinger, Mishkin, & Reynolds, 1985).
In the dog in this report, one additional radiographic series was acquired approximately 60 minutes after the images in Figure 1. In that study (Figure 4A, B) the intussusceptum is longer, larger due to edema and there is no barium in the lumen. The filling defect created by the intussusceptum is also more discrete, and the intussusceptum has a more coiled appearance.
Lamb, C., & Mantis, P. (1998). Ultrasonographic features of intestinal intussusception in 10 dogs. J Sm Anim Pract, 39, 437-441.
Levine, M. S., Trenkner, S. W., Hwerlinger, H., Mishkin, J. D., & Reynolds, J. C. (1985). Coiled-spring sign of appendiceal intussusception. Radiology, 155, 41-44.
Levitt, L., & Bauer, M. S. (1992). Intussception in dogs and cats: A review of 36 cases. Canadian Vet J, 33, 660-664.
Patsikas, M. N., Jakovljevic, J., Moustardas, N., Papazoglou, L. G., Kazakos, G. M., & Dessiris, A. K. (2003). Ultrasonographic Signs of Intestinal Intussusception Associated With Acute Enteritis or Gastroenteritis in19 Young Dogs. J Am Anim Hosp Assoc, 39, 57-66.
Wilson, G. P., & Burt, J. K. (1974). Intussusception in the dog and cat: A review of 45 cases. J Am Vet Med Assoc(164), 515-518.