CTA for Internal Herniation After RYGB Surgery

Introduction: Morbid obesity, defined as a body mass index (BMI) of over 40 kg/m2, is globally an imminent health threat. Conservative therapies do often not yield the desired result. Bariatric surgery includes several interventions that are performed on patients with morbid obesity, like gastric bypass surgery. The number of bariatric surgeries annually is estimated to be around 500,000 worldwide; about half of these are gastric bypass surgeries. In the Netherlands, the most common performed bariatric intervention is the Roux-en-Y gastric bypass (RYGB). An important long-term complication of this surgery is internal herniation, a condition in which a part of the GI tract is herniated through an opening in the mesentery made during RYGB surgery. Incidence of internal herniation is 1-5%. Conventional abdominal CT examination is often not conclusive about the presence of internal herniation. When internal herniation is clinically highly suspected after abdominal CT examination (but not necessarily confirmed), the patient is subjected to diagnostic laparoscopic surgery. Unfortunately, a negative abdominal CT scan does not exclude internal herniation in all patients. This pleads for the development or exploitation of alternative techniques that might aid in the diagnosis of complications after RYGB surgery. Since the anatomy of GI tract is altered when internal herniation is present, visualizing the mesenteric vasculature may aid in the diagnosis of this complication after RYGB surgery. This study aims to confirm the feasibility and superiority of diagnosing internal herniation using CT examination of the mesenteric arteries over conventional CT examination.

Objectives: The primary objective is to determine whether abdominal arterial CT angiography is a feasible technique for diagnosing internal herniation after RYGB surgery. Secondary, it is examined whether arterial angiography of the mesentery is superior over conventional CT examination with oral and IV contrast in the venous phase.

Study design: This study will be a prospective pilot study, in which the outcomes of both the conventional CT examination and abdominal angiogram are compared to the outcome of diagnostic laparoscopy as gold standard.

Study population: Patients will be included who underwent laparoscopic RYGB surgery at least half a year earlier and have persisting abdominal pain. They should be highly suspected for internal herniation by their doctor, based on several characteristics.

Main study parameters/endpoints: Primary study endpoints are the assessments of the arterial abdominal angiogram and mesenteric arterial mapping in relation to the outcome of the diagnostic laparoscopic surgery in 12 subjects.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness: In this pilot study, study subjects will receive an additional effective radiation dose of about 10 mSv. On average, an acute dose of 10 mSv leads to an additional risk of cancer of about 1 in 1750 (~1 in 2000 for males, ~1 in 1500 for females) for a 50-year old subject, based on the linear no threshold model. However, when the mesenteric artery mapping proves to be feasible and superior, many unnecessary diagnostic laparoscopic surgeries will be prevented (along with their complications and risks).