Inflammation and infarction of adipose tissue: implications in bariatric surgery

Abstract

Fat necrosis occurs more frequently in patients who have obesity and diabetes mellitus and is linked to worsening of diabetes. Little evidence is available about surgical complications that are related to inflammation and necrosis of adipose tissue. We report two cases of young women with diabetes who underwent bariatric surgery and had complications resulting from extensive inflammation and necrosis of adipose tissue. The first patient was diagnosed with omental infarction, which is a type of fat necrosis that is rarely associated with obesity and bariatric surgery. The second patient had an intraoperative finding of mesenteric panniculitis, which resulted in an intra-operative change in the choice of bariatric surgery to do a sleeve gastrectomy instead of a gastric bypass. Surgeons who perform surgery on bariatric patients must be aware of complications related to excessive amount of adipose tissue.

Background

Obesity is commonly associated with conditions such as diabetes, hypertension and obstructive sleep apnoea. However, fat necrosis and inflammation caused by morbid obesity is a rare entity, and is not well reported in the literature. We describe the presentation and management of an unusual complication/intraoperative finding in two patients who underwent bariatric surgery. It is important for bariatric surgeons to be aware of fat necrosis and inflammation as they can lead to significant and even potentially life-threatening complications such as sepsis.

Case history

Case 1

A 42-year-old woman, body mass index (BMI) 40kg/m², had an extensive medical history including severe asthma (on prednisolone), gastro-oesophageal reflux disease and obstructive sleep apnoea requiring continuous positive airway pressure ventilation. She also had Type 2 diabetes mellitus and a history of dilated cardiomyopathy with a pacemaker in situ. Her case was discussed in the bariatric multidisciplinary team meeting and the decision was made that a laparoscopic Roux-en-Y gastric bypass would be a suitable surgical option.

During surgery, the very thick greater omentum was split using the Ligasure device and a triple-stapled jejunojejunostomy and a lesser curve based gastric pouch was created. A circular stapled gastrojejunal anastomosis was performed with the Orvil device (25mm/3.8mm staple height). Both the Petersen’s and jejunojejunostomy mesenteric defects were closed. Postoperatively, the patient recovered well and spent one night in HDU and was discharged on postoperative Day 3. Three weeks later she developed epigastric pain and computed tomography of the abdomen and pelvis (CTAP) revealed an 8×6cm area of omental infarction (Fig 1A). The patient was admitted and commenced on intravenous broad-spectrum antibiotics and analgesia.

Figure 1.

Transverse views of computed tomography of the abdomen and pelvis with intravenous contrast of Case 1. The scan demonstrates just below the anterior abdominal wall an inflammatory mass with scirrhous reaction and fat stranding with tethering of proximal bowel to the anterior abdominal wall consistent with omental infarction (A). Ten days later, there was an increase in the extent of the inflammatory focus, within the anterior upper abdomen, and a prominent fluid component (B).

Over the next week, the patient improved clinically but on Day 8 developed a fever, worsening abdominal pain and inflammatory markers. A repeat CTAP demonstrated a degree of liquefactive necrosis of the infarcted omentum (Fig 1B). This was not amenable to radiological percutaneous drainage and, in view of her sepsis, the decision was made to perform a laparoscopic drainage of the omental abscess (100ml of frank pus) and removal of the necrotic omental tissue. The patient had an uneventful recovery and was then discharged. Four months later she had a BMI of 34kg/m² and was well.

Case 2

A 56-year-old woman, BMI 41kg/m², had a history of mild asthma, Type 2 diabetes mellitus and three previous Caesarean sections. During planned LRYGB, it was noted she had extensive mesenteric panniculitis and the small bowel mesentery was adherent to adjacent small bowel loops and the transverse mesocolon. After a trial dissection to separate the jejunal small bowel loops, a decision was made instead to perform a laparoscopic sleeve gastrectomy (LSG). She recovered well and was discharged on postoperative Day 2. In view of the surgical findings, CTAP was performed six weeks later, which showed evidence of mesenteric panniculitis, entero-colitis and a well-formed sleeve (Fig 2). She was managed conservatively and referred to the Gastroenterology service to exclude inflammatory bowel disease. Six months postoperatively, the patient continued to make very good progress (BMI 35kg/m²).

Figure 2.

Coronal view of computed tomography of the abdomen and pelvis with intravenous contrast of Case 2 revealed submucosal fat deposition in the terminal ileum and right colon, which is a possible sequelae of chronic enterocolitis, and changes within the small bowel mesentery suggestive for mesenteric panniculitis.

Discussion

An omental infarction or abscess following laparoscopic Roux-en-Y gastric bypass is not well documented in the literature, nor are the implications of mesenteric panniculitis in bariatric surgery. These two cases demonstrate that an extreme amount of visceral and subcutaneous adipose tissue can have serious perioperative complications and important consequences on the choice or outcome of surgery.

We believe that our first patient developed an omental infarction due to the large amount of adipose tissue and long-term steroid use. Omental infarction is a specific type of fat necrosis and is a rare event resulting from the presence of abundant collateral vessels.¹ Omental infarction can be defined as either primary (related to vascular compromise such as omental torsion, obesity, hypercoagulable states or heart failure) or secondary (following abdominal surgery due to a reduction in omental vascular supply as a result of inflammation, venous thrombosis, artery ligation or kinking due to adhesions).² Omental infarction can mimic cholecystitis or acute appendicitis with CT being the imaging modality of choice.¹ Treatment includes supportive management or laparoscopic resection of the necrotic omentum. Abrisqueta et al opted for the latter because of possible complications arising from the necrotic segment, such as intra-abdominal abscesses or adhesions, and the need for interval CT.² In our case, we consulted a group of international bariatric surgeons (www.ibcclub.org) after the patient failed to respond to medical management. A decision was made to perform a laparoscopic drainage of the omental abscess and resection of the necrotic omentum which resulted in an effective resolution of her sepsis.

Mesenteric panniculitis, as seen with our second patient, involves chronic inflammation and fibrosis of adipose tissue of the mesentery, usually that of the small bowel.³ Although a definitive cause has not yet been established, it is reported to be more common in patients with prior abdominal surgery or trauma, abdominal or pelvic malignancies, autoimmune disease, diabetes and pancreatitis. Mesenteric panniculitis is also related to adhesions, obesity-induced immune dysfunction and anatomical, metabolic and biochemical characteristics of adipose tissue.⁴

We initially performed omental adhesiolysis as the patient had undergone multiple caesarean sections. The small bowel was enveloped by adhesions and after a trial of dissection, the decision was made to convert to LSG due to extensive inflammation and mesenteric panniculitis.

Other complications of mesenteric panniculitis include bowel obstruction or ischaemia and chylous ascites. Mesenteric panniculitis is often self-limiting and can be managed with supportive measures and anti-inflammatory analgesics. Other studies have suggested the use of immune-modulatory or anti-fibrotic agents such as corticosteroids, colchicine, cyclophosphamide or tamifoxen.⁵ If medical therapy is unsuccessful, surgery may be required to correct bowel, vascular or ureteric obstruction.

In conclusion, omental infarction is associated with obesity and abdominal surgery. It should be considered as a potential diagnosis in obese patients with abdominal pain following gastric bypass surgery particularly if there are other confounding factors such as long-term steroid use. A multidisciplinary team approach is essential to prevent adverse outcomes of omental infarction and abscesses. We have also highlighted the importance of mesenteric panniculitis as an intraoperative finding during bariatric surgery and how this may influence the surgeon’s decision making and patient outcome. Future research is needed to understand in more detail this unusual pathology and its associated significant complications.