Colonic dilation with no clear mechanical cause/transition point. A colonic pseudo-obstruction (also known as Ogilvie syndrome) was considered as a possibility due to the post-operative status and associated electrolyte disturbances. Patient improved one day later only with clinical management. 

Adynamic ileus, which is usually associated with small bowel dilation, is a differential, although both conditions have a similar clinical management. Toxic megacolon secondary to Clostridioides difficile colitis and ischemic colitis would present with similar dilation, but associated with bowel wall thickening and associated inflammatory changes such as fat stranding. 

Right kidney complex cyst was recommended for ultrasound correlation.