Mannitol as Oral Contrast for CT abdomen- a Cost effective CT Enterography agent

Teaching Points on CT Enterography by Dr MGK Murthy, MD, DNB

1.    Practice of Positive Oral contrast (Iodine based like Urograffin)  is being replaced by Negative/Neutral contrast agents including water with or without mannitol addition(for small bowel distension).  100 ml bottles of Mannitol 20%(Weight by volume)  are popular  as single patient use . Please carefully open the seal and add  drinking water to make  the total volume to 2000 ml (i.e. approximately about 1900 ml added ). Administer  1300ml out of this  slowly over 50 minutes to an hour  duration, before taking up the patient .Give an additional  200 ml  (Total consumption would be 1500ml) before starting the scan ,on the table , to augment  distension of stomach/duodenum. (balance amount of 200 ml to be discarded)

2.    In CT - PET scan, this drinking may mildly activate the increased  pharyngeal  uptake of FDG , which however does  not pose any  significant  diagnostic difficulty .

3.    If a patient  is on" NIL  orally"  instructions  with stomach tube - NO ORAL CONTRAST  is the rule. In case  of very Critically ill patients/ Very elderly (usually above 75 yrs +)/ haemodynamically compromised patients (particularly on dialysis or acute cardiac patients etc ) or small babies (usually below 5 years) and  PREGNANT (of course we should  be avoiding   abdominal CT),   use your   discretion based on Individual  needs. 

4.    In case of any doubt, Plain drinking water is most non controversial  (non distending )oral negative agent  Administration of IV buscopan is  preferred if Enterography is needed rather than routine Abdominal CT 

5.    Small bowel  CT Enterography with oral mannitol and IV buscopan is  gradually replacing Enteroclysis