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CT scan is predictive of internal herniation if mesenteric defect is closed

Wed, 11/18/2020 - 11:47
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A computer tomography (CT) scan can be predictive for the diagnosis of internal herniation (IH), if the mesenteric defect is closed following Roux-en-Y gastric bypass (RYGB), however, the diagnostic accuracy of a CT scan is not useful in a patient with open mesenteric defect, according to researchers from Leiden University Medical Center, Leiden and the Dutch Obesity Clinic West & LUMC, The Hague, The Netherlands. The findings, ‘Internal Herniation Incidence After RYGB and the Predictive Ability of a CT Scan as a Diagnostic Tool’, were published in Obesity Surgery.

According to the researchers, although IH is a well-known late complication of a RYGB and several papers have reported, examined and assessed IH incidence, prevention and diagnostics. there is still no consensus on standardised closing of mesenteric defects and the use of a CT scan for the diagnosis of the IH. Moreover, they noted that there is also uncertainty as to whether the sensitivity and specificity of the CT scan are different when mesenteric defects were closed or left open.

In 2013, the authors clinic changed its policy from leaving mesenteric defects open to closing them, giving allowing the researchers to assess the incidence of IH in patients with and without closed mesenteric defects, as well as examining whether the accuracy of a CT scan is different in patients with and without closed mesenteric defects.

For their retrospective single-centre cohort study, all patients who underwent a primary laparoscopic RYGB between January 2011 and December 2016 were selected from hospital electronic databases to see if they had undergone a re-laparoscopy after RYGB or not.

A patient was selected if they presented at the emergency department with complaints with intermitted pain in the upper (left) abdomen, related to complaints after a meal with or without other obstruction complaints. The patient received a re-laparoscopy and a CT scan was performed in cases whereby the complaints could predict alternative diagnoses. The CT was reported in the patient electronic file. Re-operations were performed in 100% of the cases. For this analysis, patients were divided in four groups:

  • Group A is the non-closed group who underwent a CT
  • Group B is the non-closed group without CT
  • Group C is the closed group who underwent a CT; and
  • Group D is the closed group without CT scan

In total, 133 patients (4.1%, from 3,262 who had a RYGB between January 2011 and December 2016) were re-operated for suspected IH and were included in this study. The majority were female 119 (89.5%), the mean ± SD age was 44.56±9.7 years old and the mean ± SD preoperative BMI before bariatric surgery was 43.3±12.1kg/m2. At the time of re-operation, the mean ± SD BMI was 29.7±6.5kg/m2 and total weight loss was 31.1%. The average time between RYGB and IH was 17.98±11.2 months. The authors reported no significant differences in baseline characteristics between the patients who were diagnosed or suspected with IH and the patients who were not.

In a majority of patients (n=77, 57.9%) elective surgery was scheduled, the remaining patients (n=56, 42.1%) were re-operated on in the acute phase, in nine cases (6.8%) laparoscopy was converted because of insufficient exposure and in the remaining cases (n = 124/93.2%) all patients were successfully performed laparoscopically (p=0.03).

From January 2011 and June 2013, of the 1058 patients underwent a RYGB 62 patients - who had their mesenteric defect left open - were suspected of IH and underwent a re-operation. In the group of patients with closed mesenteric defect 71 patients (from 2,204) underwent a re-operation. Therefore, the authors reported that the rate of re-operation in the non-closed group was significantly higher (5.8%) than that in the closed group (3.2%, p=0.001). The incidence of IH was also significantly higher in non-closed group (3.9%), compared with the closed group (1.3%, p=0.001).

In comparing the four groups, the authors reported:

Group A - 16 patients were in the non-closed group who underwent a CT scan, the sensitivity of the CT scan was 80% and specificity was 0%. The positive predictive value of the CT scan in this group was 92%, and the negative predictive value was 0%.

The authors explained that with the high sensitivity, it is assumed that a patient is not sick with a negative test result and no treatment is necessary. As the sensitivity decreases, the number of false negatives will increase, although the risk is patients who are sick will be sent home.

Group B – 46 patients were in the non-closed group who were re-operated without a performance of a CT scan, an IH was visible during re-operation in 58.7% of the cases.

Group C – 36 patients were in the closed group and had a CT scan and the sensitivity of the CT scan was 64.7% and specificity of 89.5%, and a positive predictive value of 84% and a negative predictive value of 74%. Therefore, with a high specificity, it is assumed that a patient is really ill with a positive test result and needs treatment.

Group D – 35 patients were in the closed group without CT scan and only a re-operation was done, an IH was visible in 34.3% of the patients, and in 65.7%, it was not.

Of note, total of 42 patients had IH surgery still suffered from abdominal pains afterwards.

“After the correction of an internal herniation, three out of ten patients still have postoperative complaints,” the authors concluded. “This suggests that, in addition to an internal hernia, there are other causes for abdominal pain after RYGB.”

To access this paper, please click here