An intraoperative leak test should not be done; or should it?

Here is an abstract recently published ahead of print in the American Journal of Surgery. Please read it because a one-question test follows.

Introduction: Staple line leak after sleeve gastrectomy (SG) is a rare but dreaded complication with a reported incidence of 0-8%. Many surgeons routinely test the staple line with an intraoperative leak test, but there is little evidence to validate this practice. In fact, there is a theoretical concern that the leak test may weaken the staple line and increase the risk of a postop leak.

Methods: Retrospective review of all SG performed over a 7-year period. Cases were grouped by whether an intraoperative leak test (IOLT) was performed, and compared for the incidence of postop staple line leaks. The ability of the IOLT for identifying a staple line defect and for predicting a postoperative leak was analyzed.

Results: 542 SG were performed between 2007-2014. 13 patients (2.4%) developed a postop staple line leak. The majority of patients (N=494, 91%) received an IOLT, including all 13 patients (100%) who developed a subsequent clinical leak. There were no (0%) positive IOLTs and no additional interventions were performed based on the IOLT. The IOLT sensitivity and positive predictive value were both 0%. There was a trend, although not significant, to increased leak rates when a routine IOLT was performed versus no routine IOLT (2.6% vs. 0%, p=0.6).

Conclusions: The performance of routine IOLT after sleeve gastrectomy provided no actionable information, and was negative in all patients who developed a postoperative leak. The routine use of an IOLT did not reduce the incidence of postop leak, and in fact was associated with a higher leak rate after SG.

Do you agree with the authors that the routine use of the IOLT was associated with a higher leak rate after sleeve gastrectomy?

Read the whole paper not just the abstract

Here is another installment in my series of posts about why you should read the entire paper and not just the abstract. (See others here, here and here.)

A paper in the February 2013 issue of the Journal of the American College of Surgeons describes 15 cases of median arcuate ligament syndrome treated with laparoscopic surgery.

Median arcuate ligament syndrome (MALS) is somewhat controversial. It is said to be due to impingement of the median arcuate ligament (a portion of the diaphragmatic crura) on the celiac artery causing a narrowing and decreased perfusion of the stomach. Symptoms are abdominal pain after eating, nausea and weight loss. It is often diagnosed in patients who have been worked up for many other suspected problems without finding anything.

The paper notes that 10% to 60% of people without symptoms have narrowing of the celiac artery.

The abstract reports resolution of the pain for 14 of the 15 patients who had the surgery as well as a significant mean decrease in celiac velocity indicating resolution of the narrowed area postoperatively.

It also mentions that one patient required conversion to open surgery but doesn't say why.

On reading the whole paper, one learns that the conversion to open occurred in the only case that was done with robotic assistance.

The authors state that the 2 mm injury to the aorta was the result of the robotic instrument being too large and "the absence of haptic feedback," which is robot-speak for "you can't feel anything."

That is one drawback of the robot. With robotic instruments the sense of touch is simply not present. Although the fingertips used in old-fashioned open surgery are much more sensitive than instruments used in standard laparoscopic surgery, those instruments do enable the surgeon to at least feel some variations in tissues

The aortic tear led to two liters of blood loss and an operative time of just under 8 hours.

The abstract says all but one patient had complete resolution of pain, but the paper says the amount of decrease in the Doppler celiac velocity "did not correspond to the degree of symptom resolution."

And you can see that the differences in preop (red) and postop (green) velocities are pretty modest in 7 of the 10 patients who had them measured even though the mean difference was significant at a p of 0.005. In addition, the postop values all hover around 200 cm/sec, which, in the presence of symptoms, was the threshold for doing the operation.

In fairness, of the 13 patients who were interviewed, all said they were satisfied with the outcome of the surgery and would go through it again.

In some ways, MALS reminds me of internal mammary artery ligation, which was once touted as a cure for angina pectoris (chest pain of cardiac origin). Over 50 years ago, randomized trials which included a sham operation—incisions were made, but the arteries were not ligated—showed that ligating the arteries was no better than the sham operation for relieving pain.

It might be time for such a trial in MALS, only let's skip the robot for this one.

Thanks to Dr. Michael Burchett for alerting me to the MALS paper.

Does the timing of appendectomy influence the wound infection rate?

“Yes,” says a large review of a single institution’s experience with appendectomy for acute appendicitis.

The study looked at over 4500 patients who underwent appendectomies over the 8-year period between 2003 and 2011. The main findings of the study were that patients who developed surgical site infection (SSI) had a significantly longer delay in going to the operating room. Time to appendectomy was defined as the time the patients were admitted to the surgery service until they reached the operating room (OR).

Patients who developed infections were taken to the OR after a mean of 14 1/2 hours compared to 11 hours and 45 minutes for those who did not, which was a statistically significant difference, p = 0.013.

The delay in taking patients to the operating room did not lead to more perforations. However, the rate of perforation in this series was rather high at 23%.

The abstract concluded, "prompt surgical intervention is warranted to avoid additional morbidity in this population."

Since this paper supports my bias about performing appendectomies as soon as the diagnosis is made (as I have previously blogged), I was hoping that its findings would be valid. Unfortunately, that is not the case. The paper is not as convincing as the abstract.

The authors state that surgeons and operating room personnel are in the hospital 24 hours a day. It is not clear why patients’ operations were delayed so long. There is no mention of whether the patients received antibiotics while they were waiting. If more patients who did not suffer SSI's had received antibiotics, the paper’s results could be misleading. If you look at the mean difference between times to the operating room for non-infected versus the infected patients, you will note that it is a little less than 3 hours, which really is not that long.

Another issue is that only 41% of the patients underwent laparoscopic appendectomy. In my practice and that of most other surgeons, 90%-95% of patients with appendicitis are operated on via the laparoscopic approach. Laparoscopic appendectomy is known to have a lower wound infection rate than open.

The mean hospital length of stay for the non-perforated patients was 3.4 days, highlighting the outdated nature of the information. Most patients with non-perforated appendicitis are discharged within 24 hours of surgery in 2012.

However the most important problem with the paper has to do with the key factor that the paper emphasized; that is time. Not only was the duration of the patients’ symptoms prior to arrival at the hospital unknown, the authors also did not account for the length of time that the patients spent in the emergency department. If diagnostic CT scans, which are done about 90% of the time for appendicitis, were performed, the patients probably spent at least 6 hours in the ED.

It does not stand to reason that a less than 3-hour average difference in taking patients to the operating room when the preop duration of symptoms is unknown could possibly be significant. And 11 hours and 45 minutes to get a patient to the OR does not define “prompt” for me.

Bottom line: As I have said before (here and here), you have to read the entire paper and not just the abstract.