Imaging of small bowel-related complications following major abdominal surgery

Oncologic surgical complications: Imaging approach and characteristics

Cancer is a disease that has multisystemic facets in its diagnosis and management. The treatment of choice with curative intent in many sites is surgery for early disease, commonly combined with neoadjuvant or adjuvant treatment. Oncologic surgery can have both locoregional and systemic complications, occasionally accentuated by multimodality treatment. While complications are of concern in any surgical setting, they may have specific intricate implications in the care of a cancer patient. Diagnostic imaging provides a non-invasive means of detecting complications and communicating the findings to the rest of the team for decision-making. Clinical clues, site-specific considerations and visual characteristics can aid the radiologist in arriving at a diagnosis of a locoregional oncologic surgical complication. Knowledge of systemic or distant complications, their clinical and imaging characteristics is a must-know following oncologic surgery. This article as an educational narrative review addresses imaging approach and characteristics of oncologic surgical complications, by pairing clinical considerations and imaging aspects.

Postoperative Ileus and Postoperative Gastrointestinal Tract Dysfunction: Pathogenic Mechanisms and Novel Treatment Strategies Beyond Colorectal Enhanced Recovery After Surgery Protocols

Postoperative ileus (POI) and postoperative gastrointestinal tract dysfunction (POGD) are well-known complications affecting patients undergoing intestinal surgery. GI symptoms include nausea, vomiting, pain, abdominal distention, bloating, and constipation. These iatrogenic disorders are associated with extended hospitalizations, increased morbidity, and health care costs into the billions and current therapeutic strategies are limited. This is a narrative review focused on recent concepts in the pathogenesis of POI and POGD, pipeline drugs or approaches to treatment. Mechanisms, cellular targets and pathways implicated in the pathogenesis include gut surgical manipulation and surgical trauma, neuroinflammation, reactive enteric glia, macrophages, mast cells, monocytes, neutrophils and ICC's. The precise interactions between immune, inflammatory, neural and glial cells are not well understood. Reactive enteric glial cells are an emerging therapeutic target that is under intense investigation for enteric neuropathies, GI dysmotility and POI. Our review emphasizes current therapeutic strategies, starting with the implementation of colorectal enhanced recovery after surgery protocols to protect against POI and POGD. However, despite colorectal enhanced recovery after surgery, it remains a significant medical problem and burden on the healthcare system. Over 100 pipeline drugs or treatments are listed in Clin.Trials.gov. These include 5HT4R agonists (Prucalopride and TAK 954), vagus nerve stimulation of the ENS-macrophage nAChR cholinergic pathway, acupuncture, herbal medications, peripheral acting opioid antagonists (Alvimopen, Methlnaltexone, Naldemedine), anti-bloating/flatulence drugs (Simethiocone), a ghreline prokinetic agonist (Ulimovelin), drinking coffee, and nicotine chewing gum. A better understanding of the pathogenic mechanisms for short and long-term outcomes is necessary before we can develop better prophylactic and treatment strategies.

Multi-Modality Imaging Evaluation of the Whole-Organ Pancreas Transplant

Pancreas transplants are an important treatment options for patients with severe diabetes mellitus and other medical conditions. Multiple-imaging modalities, including computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound (US) are available to evaluate the pancreas transplants and their vascular supply, with the graft having a characteristic appearance on each modality. Complications of the graft and its vascular supply present interesting challenges to the clinicians and radiologists caring for this patient population. Being able to identify the imaging appearance of normal and abnormal pancreas transplants, it is necessary to ensure these patients are provided optimal care.

Postoperative ileus: in search of an international consensus on definition, diagnosis, and treatment

PURPOSE

Postoperative ileus (POI) is a frequent complication after abdominal surgery; nonetheless, it remains poorly defined. Our aim was to achieve an international consensus among leading colorectal surgeons on definition, prevention, and treatment of POI.

METHODS

Thirty-five experts from five continents participated in a three-round Delphi process. Round 1 contained open-ended questions on POI and postoperative nausea and vomiting (PONV). Round 2 included closed-ended questions. Round 3 measured agreement on a 5-point Likert scale. Consensus was defined when items were rated as agree or strongly agree by at least 70 % of the experts.

RESULTS

Experts reached following consensus: POI is a temporary inhibition (86 %) of gastrointestinal motility after surgical intervention due to non-mechanical causes (89 %) and prevents sufficient oral intake (96 %). Abdominal distension/tenderness are the most relevant clinical signs (71 %). Nasogastric tube placement is not mandatory (78 %) but can be removed without previous clamping (81 %)/gastrointestinal contrast study (100 %). Preventive measures are recommended to decrease the risk of POI (96 %): narcotic sparing analgesia (89 %) and fluid optimization (74 %). Treatment of POI should include stimulation of ambulation (96 %) and stop of opioids (74 %). Total parenteral nutrition is recommended from the 7th day without sufficient oral intake (81 %). There was no consensus on the ranking of POI's symptoms, on the imaging modality of choice for the diagnosis of POI, neither on the difference between POI and PONV.

CONCLUSIONS

This Delphi study achieved consensus on the definition, relevant clinical signs, prevention, treatment, and supportive care of POI. Areas of non-consensus were identified (necessity and modality of radiologic imaging to establish the diagnosis, difference between POI and PONV), giving opportunity for further research.

Imaging the postoperative patient: long-term complications of gastrointestinal surgery

OBJECTIVES

The objectives of this review are (1) to become acquainted with the long-term complications of surgery of the gastrointestinal tract, and (2) to appreciate the appropriate use of imaging in the assessment of long-term complications.

BACKGROUND

Gastrointestinal tract surgery comprises a group of procedures performed for a variety of both benign and malignant diseases. In the late postoperative setting, adhesions and internal hernias are the most important complications. and they can be further complicated by volvulus and ischemia. At present, computed tomography (CT) is the workhorse for evaluating late postoperative complications. Accurate imaging assessment of patients is essential for adequate treatment planning.

IMAGING FINDINGS OR PROCEDURE DETAILS

In this pictorial essay we will review the most frequent long-term complications after gastrointestinal surgery, including adhesions, afferent loop syndrome, closed-loop obstruction, strangulated obstruction, internal hernias, external hernias, anastomotic strictures and disease recurrence. Examples will be depicted using iconography from the authors' imaging department.

CONCLUSIONS

Knowledge of the most frequent complications after gastrointestinal surgery in the late postoperative period is of paramount importance for every radiologist, so that potentially life-threatening situations can be promptly diagnosed and adequate therapy can be planned.

TEACHING POINTS

• Long-term postoperative complications of gastrointestinal tract surgery can be divided into procedure-related and disease-related categories. • The most common procedure-related complications are internal hernias and adhesions. • The most frequent disease-related complications are mainly associated with neoplastic or inflammatory recurrence. • Computed tomography is the most useful examination when such complications are suspected.

Management of afferent loop obstruction: Reoperation or endoscopic and percutaneous interventions?

Afferent loop obstruction is a purely mechanical complication that infrequently occurs following construction of a gastrojejunostomy. The operations most commonly associated with this complication are gastrectomy with Billroth II or Roux-en-Y reconstruction, and pancreaticoduodenectomy with conventional loop or Roux-en-Y reconstruction. Etiology of afferent loop obstruction includes: (1) entrapment, compression and kinking by postoperative adhesions; (2) internal herniation, volvulus and intussusception; (3) stenosis due to ulceration at the gastrojejunostomy site and radiation enteritis of the afferent loop; (4) cancer recurrence; and (5) enteroliths, bezoars and foreign bodies. Acute afferent loop obstruction is associated with complete obstruction of the afferent loop and represents a surgical emergency, whereas chronic afferent loop obstruction is associated with partial obstruction. Abdominal multiple detector computed tomography is the diagnostic study of choice. CT appearance of the obstructed afferent loop consists of a C-shaped, fluid-filled tubular mass located in the midline between the abdominal aorta and the superior mesenteric artery with valvulae conniventes projecting into the lumen. The cornerstone of treatment is surgery. Surgery includes: (1) adhesiolysis and reconstruction for benign causes; and (2) by-pass or excision and reconstruction for malignant causes. However, endoscopic enteral stenting, transhepatic percutaneous enteral stenting and direct percutaneous tube enterostomy have the principal role in management of malignant and radiation-induced obstruction. Nevertheless, considerable limitations exist as a former Roux-en-Y reconstruction limits endoscopic access to the afferent loop and percutaneous approaches for enteral stenting and tube enterostomy have only been reported in the literature as isolated cases.

Can postoperative complications be predicted by a routine CT scan on day 5? A study of 78 laparoscopic colorectal resections

BACKGROUND

Postoperative computed tomography (CT) scan patterns after colorectal resection are difficult to analyze for both clinicians and radiologists. This study aimed to assess the role of single CT scan on postoperative day 5 in predicting postoperative morbidity.

METHODS

From October 2007 to August 2009, 78 patients undergoing laparoscopic colorectal resection were enrolled in a research study involving a routine contrast-enhanced multi-detector CT scan on postoperative day 5. Two groups were defined: patients with intra-abdominal postoperative morbidity requiring specific management, i.e., surgical or radiological procedure, and/or antibiotic therapy ("complications" group), and patients with uneventful postoperative outcome ("uneventful" group). CT findings were compared between the two groups with Fisher's exact test or chi-square test.

RESULTS

Postoperative abdominal complications occurred in 16 patients (21 %). Of the CT findings on day 5, pneumonia, pulmonary embolism, portal or mesenteric thrombosis, operative area fat infiltration, peritoneal effusion, pneumoperitoneum, intra-abdominal collection, parietal inflammation or collection, and subcutaneous emphysema were observed in both groups without any significant difference. Only small bowel distension [25 % (4/16) in the "complications" group vs. 5 % (3/62) in the "uneventful" group; p = 0.029] and pleural effusion [81 % (13/16) vs. 48 % (30/62); p = 0.024, respectively] were observed significantly more often in the "complications" group.

CONCLUSIONS

This study suggested that abdominal complications cannot be predicted by a CT scan on day 5 after laparoscopic colorectal resection. Thus, it cannot be recommended for routine use.

Acute intestinal failure

PURPOSE OF REVIEW

The review aims to highlight the importance of acute gastrointestinal failure in the postoperative patient, to clarify the clinical circumstances in which acute intestinal failure complicates postoperative management, and to discuss recent advances and controversy in our understanding of the cause and pathogenesis.

RECENT FINDINGS

Acute postoperative intestinal failure ranges from a self-limiting condition of disordered intestinal peristaltic activity, through to a complex critical illness state associated with abdominal sepsis and intestinal fistulation. Recent developments have focused on the mechanisms of paralytic ileus and preventive strategies, usually as part of programmes of 'fast-track' or 'enhanced recovery' care, and on the optimum management of patients with severe abdominal sepsis, including planned versus on-demand relaparotomy, open abdominal management of severe sepsis and negative pressure wound therapy.

SUMMARY

Many cases of acute intestinal failure are preventable. Improvements in understanding and preventing paralytic ileus through changes in postoperative care may facilitate recovery of gastrointestinal function after abdominal surgery. Further and better-organized studies are needed to define the optimum strategies for treating patients with severe abdominal sepsis, managing the patient with the open abdomen and defining the role of enteral, as opposed to parenteral nutritional support in such patients.

Small bowel obstruction: the art of management

Strategies for the management of small bowel obstructions have changed significantly over the years. Nonoperative medical management has become the mainstay of treatment of many small bowel obstructions. However, the key to the management of small bowel obstructions is identifying those patients who need surgical intervention. Identification of those at risk for bowel ischemia and bowel death is an art as much as it is a science. Using the current literature and the past knowledge regarding small bowel obstructions, the clinician must carefully identify the signs and symptoms that suggest the need for operative intervention. Classification of the obstruction, history and physical examination, imaging, response to decompression and resuscitation, and resolution or progression of symptoms are the key factors influencing the management of small bowel obstructions.

Assessment of appropriateness of indications for CT enterography in younger patients

BACKGROUND

The small potential risk of radiation-induced cancer is increased in younger patients undergoing serial imaging with computed tomography enterography (CTE). We sought to determine the appropriateness of CTEs based on clinical indication in patients < or =35 years old, and the potential impact of evolution of practice to alternative magnetic resonance enterography (MRE).

METHODS

Over a 7-year period, the medical records of all patients < or =35 years old undergoing CTE were reviewed to determine the clinical indications for each CTE exam. An interdisciplinary consensus panel evaluated the appropriateness of all CTE exams based on American College of Radiology appropriateness criteria and peer-reviewed literature, classifying indications into "appropriate" or "inappropriate." For repeat CTEs, an "alternative MRE suggested" pathway was created. Criteria for evolution of practice to "alternative MRE" were suspicion of obstruction and evaluation of disease activity/therapeutic response in the absence of new symptoms.

RESULTS

In all, 2022 patients < or =35 years old underwent 2295 CTEs. Ninety-nine percent (2008/2022) of first-time CTE exams were "appropriate" by the defined criteria. A total of 197 patients (9.7%) underwent multiple exams, with 73% of these patients having Crohn's disease. Repeat exams occurred in 9% (18/197) with obstructive symptoms and evaluation of disease activity/therapeutic response in the absence of new symptoms in 41% (80/197).

CONCLUSIONS

A multidisciplinary expert panel concluded that the vast majority of young patients underwent clinically appropriate first-time CTE exams. However, a shift in clinical practice to MRE appears warranted for approximately half of young patients undergoing repeat CTE examinations.

Ischemia and infarction of the intestine related to obstruction

In the acute obstructive syndrome, beyond the evaluation of the morphologic findings of the intestine (e.g. dilation, air-fluid level, whirl sign, transition point), it is important to consider the pathophysiology of the bowel wall in order to better estimate the status of viability, the degree of the obstruction and the presence of the intestinal ischemic complications or infarction: the intestine is a dynamic system and the same pathological condition can appear in different forms, depending on the stage of disease. MDCT examination could be of help in differentiating various type and degree of disease of the intestinal ischemia correlated to obstruction.

Closed-Loop Small-Bowel Obstruction

Multidetector computed tomography is a highly accurate method in evaluating high-grade intestinal obstruction. Closed-loop obstruction is a relatively uncommon subcategory of small-bowel obstruction; however, it is associated with a high risk of vascular impairment and is, therefore, important to diagnose accurately. Closed-loop obstruction is often caused by conditions such as internal hernias, congenital bands, postoperative adhesions, and malrotation. The purpose of this article is to review the imaging features of closed-loop bowel obstruction and various underlying conditions. Special emphasis will be placed on the technique of multidetector computed tomography and its role in diagnosing this entity.

Bowel complications seen on CT after pancreas transplantation with enteric drainage

OBJECTIVE

Bowel-related complications from pancreas transplantation account for much of the postsurgical morbidity. In a review of 98 pancreas transplant recipients, we found 19 (19.4%) with such complications.

CONCLUSION

The most common problems were small-bowel obstruction and anastomotic leaks. Adhesions and internal hernias accounted for most postoperative bowel obstructions.