necrotic bowel

I had over two feet of my bowel removed after the colon perforated twice within the same year.  The surgeon found the bowel to be necrotic.  Why wasn't this  determined through earlier testings (MRI, CT, Colonoscopy)?  Is the necrotic bowel only determined after the surgery??

[Kaneda2112]

According to the Emergency Medicine website - "Ultrasound can be useful, especially when color Doppler is used. This test may help demonstrate the presence of bowel necrosis by showing compromised blood flow to the intussusceptum."

An intussusception is a medical condition in which a part of the intestine has invaginated into another section of intestine, similar to the way in which the parts of a collapsible telescope slide into one another. This can often result in an obstruction. The part that prolapses into the other is called the intussusceptum, and the part that receives it is called the intussuscipien.

Is that what you were diagnosed with? Wikipedia states that - "Intussusception is often suspected based on history and physical exam, including observation of Dance's sign. Per rectal examination is particularly helpful in children as part of the intussusceptum may be felt by the finger. A definite diagnosis often requires confirmation by diagnostic imaging modalities. Ultrasound is today considered the imaging modality of choice for diagnosis and exclusion of intussusception due to its high accuracy and lack of radiation. A target-like mass, usually around 3 cm in diameter, confirms the diagnosis. An x-ray of the abdomen may be indicated for evaluation of intestinal obstruction or the presence of free intraperitoneal gas; the latter finding would imply that bowel perforation has already occurred. In some institutions, air enema is used for diagnosis as the same procedure can be used for treatment"