While I can only speculate about the causes of the surgical error in which I was a participant but not a witness, I do know a few things about errors in surgery. One of the most confounding things about surgical errors (besides figuring out how to recover from them) is why they happen at all. Why, when I do the same procedure the same way every time, does this one time result in a complication?
Previous authors have spent a lot of time thinking about error taxonomy in surgery, anesthesia, and elsewhere, and while the answers aren’t always simple, they can be categorized. (The types of error that can happen in surgery are summarized nicely in this article by Cuschieri.)
Errors in execution or perception
Many surgical (and anesthetic) errors stem from differences in individual patient anatomy or physiology that reveal vulnerabilities in an existing technique or protocol—a technique or protocol that is adequate in most but not all circumstances. These can be some of the most difficult errors to identify and understand. An example might be a veterinarian who tightens the ligature around every cat’s uterine body and vessels using one pound of pressure on the first and second throw of her ligature knot. In most cats, this will be sufficient, but in a few (probably in-heat) cats, it likely will not, and those cats may bleed from the ligated vessels and perhaps require re-operation and re-ligation.
This inadequate ligature tension is an error in technique that in most cats causes no harm. In each cat, there is the possibility that it will be adequate, or not. The solution to this error would be to tie all uterine body ligatures with greater tension (say, 2 pounds of tension), or to use a cue from the patient to determine when ligature tension is adequate in that patient (such as observing tissue blanching under the ligature).
Other errors in execution in surgery may be due to lapsed attention or to a mistaken perception. Attention lapses are more plausible than one might think: proficient surgeons use habitual motions and automatic processing, rather than the more deliberate and slow techniques of the inexperienced surgeon (again, see the article by Cuschieri). This automaticity allows for efficient and minimally traumatic surgical performance and is essential to practice, but it may also allow for inattention. Often if a problem arises, the surgeon will perceive an inconsistency between her mental picture of the surgery and real life, which will focus her attention and allow her to adapt to the new surgical circumstances. If not, the problem may go unnoticed and result in a complication.
A mistaken perception may go hand in hand with automaticity or with inexperience. Anatomy varies, and the surgeon may not see what she expects to see where she expects to see it. A misidentified organ, vessel, duct, or tissue can easily be severed or ligated.
Latent (system) errors
Another type of error that happens in practice may be a systematic error, a problem in the organization and allocation of time and resources. This latent error is a gap that is present at all times, but may go unnoticed and uncorrected, especially if no harm comes from it.
Professor James Reason makes the analogy of Swiss cheese, in which each slice of cheese is a layer of defense, and it is only in certain unlucky circumstances when the holes in these layers align to allow an accident or injury to occur.
In veterinary practice, an example of a latent error might be limited or infrequent observation of patients recovering from anesthesia. In perhaps 99.8% of patients, there will be no problem if they are observed only intermittently during the period after they have begun to rouse from anesthesia but before they are fully ambulatory. But in a few patients, that gap, that latent error, will be the hole in the system through which they fall. (The post-op period is the highest risk period in small animal anesthesia – perhaps because of the inherent danger of this time period or perhaps because of this common latent error of limited observation post-operatively.)
In many practices, especially with good luck and a low volume of surgeries, this particular organizational practice may not result in a patient death for many years. If and when one finally does occur, it seems to happen out of the blue, but is really a combination of this individual patient’s physiology combined with the latent error in observation, perhaps also combined with other transient or latent circumstances.
If you are interested in learning more about human error and error taxonomy, I would recommend any of the books or articles by James Reason. For some excellent and thoughtful essays on complications and learning in surgery, read Atul Gawande, especially his books Complications, Better, and the Checklist Manifesto.
As for me, I’m doing well. Yesterday I went snowboarding and got to enjoy the remnants of snow and a blue-sky sunny day. An extra wrap of spandex around my waist (a maternity product borrowed from my sister) kept the tube and pouch snug and in place, so no wardrobe malfunctions during my outdoor fun.
Frequently asked question: I have been asked by several people whether I
still need to pee “the old fashioned way”after my recent nephrostomy tube placement. Yes! My left kidney drains into thenephrostomy bag (my newfangled bladder), while the right kidney still has a good ureter and drains into my old fashioned bladder. That means that I have to pee twice every time I go to the bathroom since I have two bladders to empty. Downside: bathroom visits take twice as long. Upside: I only have to go to the bathroom half as often.
On the same day my 
