Friend died after colon surgery

  Hello--I am very confused and sad and need help in understanding the recent death of a friend of my family. He was 75 and in outstanding health, active every day, travelling, etc.  About a month ago, he had a physical exam including a barium procedure (this was supposed to be needed every five years). From the results of the barium procedure, he was given an outpatient colonoscopy.  There was one large polyp which required inpatient surgery.  This polyp was biopsied and found benign.  He was kept in the hospital six days, which alarmed me, but the only explanation I've heard is that his physicians wanted to be certain that he had no obstruction.  Four days after his release he started nonstop hiccuping and was readmitted for a second surgery to remove an obstruction caused by scarring from the first procedure. The very next day he had a crisis of unexplained low blood pressure.  Again he was taken to surgery, where part of his small intestine was found to be "necrotic".  This was removed and also an "omentectomy" was performed.  He developed pneumonia and was put in the ICU on a respirator while antibiotics were tried for the pneumonia and for an abdominal infection that had also developed.  The medicines didn't work and his health deteriorated by the day.  After a week of this, it was discovered that blood clots had developed in the portal vein and the "superior mesenteric vein". These clots were believed to have caused the earlier necrosis.  He was given heparin to dissolve the clots, but was so weak that even with the respirator he was barely alive, and he finally died yesterday.  No one seems to be able to explain how it is that a healthy and vigorous man would end up dying from what was described as a fairly routine problem.  I'd be very appreciative of any clarification you can offer.  
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Dear Leslie,
Without a detailed review of the medical record it is impossiblke to put all the events together.  Nectrotic bowel can happen in elderly people who may have compromised blood circulation ( think of it as analogous to the healthy person who suddenly has aheart attcak). Bowel infarction is a serious conditionthat could lead to the other problems and death.
This information is presented for educatuional purposes only.
HFHSM.D.-rf