OK, so you made the diagnosis of ileocolic intussusception – so let’s fix this problem. The current standard is nonoperative reduction using pneumatic pressure – the Air Contrast Enema. Some facilities use hydrostatic pressure with barium, normal saline or water soluble contrast material as well. The technique is performed under fluoroscopy to watch the intussusception reduce in real time and is 80-95% successful. Reduction under ultrasound with normal saline as the contrast material is also an option. Early studies indicate similar success rates as fluoroscopy without the downsides of radiation exposure. Check out this article for more info.
Air contrast enema is begun by inserting a (Foley) catheter into the rectum. Air (or carbon dioxide which doesn’t carry the theoretical risk of air embolism) is then pumped in, and an attached sphygmomanometer is used to monitor the pressure, which is generally best kept below 120 mm Hg. Successful nonoperative reduction is seen when contrast material (air or fluid) flows into the small bowel. Seeing a significant portion of the distal ileum rules out an ileal-ileal intussusception. Obviously if the patient feels better then you should consider the reduction as success as well.
You should obviously make sure that you adequately resuscitate the patient prior to reduction. Notify a pediatric surgeon prior to proceeding, as there is a risk of perforation. Even though this risk is approximately 1% it is better to be safe than sorry. If you had to pick, you’d rather have a perforation with air rather than fluid, and thus the preference shown towards air contrast enema in recent years. Pre-procedure antibiotics are not routinely necessary, but interestingly some children will have a slightly elevated temp (38 C) afterwards. This is theorized to be due to translocation of bacterial endotoxins/cytokines.
If the first attempt is unsuccessful some institutions have protocols for repeat enema. The time interval varies form 30 minutes to a few hours. Obviously this should only be done in stable patients. The number of repeats is not standardized, but is generally limited to 2-3. The use of repeat attempts does reduce the risk of surgery. See here, here and here for more. Though the success rate is high, situations where nonoperative treatment fails more often include:
- Intussusception present >48 hours
- Age <3 months
- Age >5 years (higher likelihood of pathologic lead point)
- When plain films show no findings worrisome for obstruction (see here for more)
Preferred when the patient has bowel perforation or if initial nonoperative techniques fail. In general symptom resolution is the best indicator of success, because small colonic filling defects can still be seen on fluoroscopy. Pre-op antibiotics should cover gut flora (second generation cephalosporin or something similar). The techniques won’t be discussed in detail here other than to state that manual reduction is the first technique in most cases. Resection with primary anastomosis is warranted if manual reduction fails. The recurrence rate is only 1% with manual reduction, and basically zero after resection.
Post-reduction management and recurrence risk
Even after successful nonoperative reduction the recurrence risk is 4%. There appears to be no difference between different forms of contrast, or flouroscopic versus ultrasound guidance. recurrences should be managed like the first episode (ie. go to air contrast enema if it worked the first time). If it recurs 2+ times a physiologic or pathologic lead point is more likely. Generally observation in the ED for 4 to 6 hours is warranted, as the recurrence risk drops off precipitously after that. Overall the recurrence risk in 24 hours is about 1 in 25. See this post for more on a great study detailing discharges home from the ED.
There are some early studies that suggest that corticosteroids may reduce the risk of recurrence of idiopathic intussusception. Perhaps the steroids calm lymphoid/Peyer’s patch hyperplasia that acts as a lead point. I personally don’t use them, as the evidence isn’t well-defined yet.
That’s all for today, tune in next time when we discuss small bowel-small bowel intussusception, which is a totally different clinical entity in many ways.