Oliver J Warren

• BSc (Hons) MBBS (Hons) MD (Res) FRCS (Gen.Surg)
• Lecturer at Imperial College London

Aim: Permanent stoma rates and time to temporary stoma reversal are key metrics in assessing left-sided colorectal resections. Timely stoma reversal is associated with improved long-term functional outcomes. Method: Prospective data capture on consecutive patients undergoing left-sided robotic resection during one surgeon's introduction of robotic...

Aim: Robotic colorectal surgery is associated with reduced blood loss and length of stay and may be of benefit in elderly patients. Method: Subgroup analysis of patients aged <65 versus >65 undergoing robotic resection during one surgeon's introduction of robotics into their high-volume practice. Results: 100 patients underwent robotic colorectal...

Aim: The introduction of robotics into colorectal surgery is increasing. Continuous, real-time outcome analysis is vital to inform and protect patients and enable cost-benefit decisions. Method: Prospective data capture on patients undergoing robotic right hemicolectomy during one surgeon's introduction of robotics into their high-volume practice....

Aim: Robotic surgery is being adopted in colorectal departments worldwide. This study reports real-word outcomes data from a single centre where multiple surgeons transitioned from laparoscopic to colorectal resections using the DaVinci system. Method: Retrospective data collection first robotic colorectal resection since its adoption into a terti...

A retrospective cohort study of patients undergoing laparoscopic inguinal hernia repair compared short- and long-term outcomes between individuals with or without history of previous abdominopelvic surgery, aiming to determine the feasibility of totally extraperitoneal (TEP) repair within this population. All patients who underwent elective TEP ing...

Introduction Subcostal hernias are categorized as L1 based on the European Hernia Society (EHS) classification and frequently involve M1, M2, and L2 sites. These are common after hepatopancreatic and biliary surgeries. The literature on subcostal hernias mostly comprises of retrospective reviews of small heterogenous cohorts, unsurprisingly leading...

Background Following ileal pouch-anal anastomosis (IPAA) for ulcerative colitis (UC), up to 16% of patients develop Crohn’s disease of the pouch (CDP) which is a major cause of pouch failure. This systematic review and meta-analysis aimed to identify preoperative characteristics and risk factors for CDP development following IPAA. Methods A litera...

Aim Complex patients have been shown to have favourable outcomes when managed under the care of the multi-disciplinary teams (MDT) 1,2. In 2019 we published our experience of a single centre complex AWH MDT and advocated its use 3 in line with EHS and a collaborative group from AWRE 2020 4,5. Expansion Further development has led to the set-up of...

Introduction This study aims to understand whether previous abdomino-pelvic (AP) surgery is a predictor of peri-operative complication in inguinal hernia surgery and if there are discrepancies between laparoscopic or open repairs. Material & Methods All patients operated on within a 5-year period were audited and subcategorised based upon history...

Introduction There is ongoing debate over whether to fix asymptomatic contralateral inguinal hernias during repair of the presenting hernia. This study reviewed the practice of one high-volume hernia surgeon, comparing unilateral and bilateral laparoscopic repairs, to establish if bilateral repair is associated with an increased risk of post-operat...

Introduction This study reviews the practice of a high-volume surgeon, comparing laparoscopic and open surgery for inguinal hernia. In suitable patients the default was laparoscopic Totally Extra Peritoneal (TEP) approach. Materials & Methods Data from patients referred over 5 years with inguinal hernias was collated prospectively and analysed ret...

The outbreak of the COVID-19 pandemic produced unprecedented challenges, at a global level, in the provision of cancer care. With the ongoing need in the delivery of life-saving cancer treatment, the surgical management of patients with colorectal cancer required prompt significant transformation. The aim of this retrospective study is to report th...

Anal Squamous Cell Carcinoma (ASCC) is a rare cancer that has a rapidly increasing incidence in areas with highly developed economies. ASCC is strongly associated with HIV and there appears to be increasing numbers of younger male persons living with HIV (PLWH) diagnosed with ASCC. This is a retrospective cohort study of HIV positive and HIV negati...

Background The incidence of incisional hernia after major abdominal surgery via a midline laparotomy is 20–41 per cent with short-term follow-up, and over 50 per cent in those surviving an abdominal catastrophe. Abdominal wall reconstruction (AWR) requires complex operations, often involving mesh resection, management of scarred skin, fistula taked...

Anal Squamous Cell Carcinoma (ASCC) is an uncommon cancer with a recognised precursor Anal Intraepithelial Neoplasia (AIN). Although there are consistent evidence-based guidelines for the management of ASCC, historically this has not been the case for AIN and as a result there have been geographical variations in the recommendations for the treatme...

Background Anal squamous cell carcinoma (ASCC) is an uncommon cancer associated with human immunodeficiency virus (HIV) infection. There has been increasing interest in providing organ-sparing treatment in small node-negative ASCC’s, however, there is a paucity of evidence about the use of local excision alone in people living with HIV (PLWH). The...

Background Colorectal multidisciplinary teams (CR MDTs) were introduced to enhance the cancer care pathway and allow for early investigation and treatment of cancer. However, there are no ‘gold standards’ set for this process. The aim of this study was to review the literature systematically and provide a qualitative analysis on the principles, org...

IntroductionAbdominal wall herniation (AWH) is an increasing problem for patients, surgeons, and healthcare providers. Surgical-site specific outcomes, such as infection, recurrence, and mesh explantation, are improving; however, successful repair still exposes the patient to what is often a complex major operation aimed at improving quality of lif...

Background This study investigated whether a quantitative faecal immunochemical test (FIT) could be used to select patients with either high- or low-risk symptoms of colorectal cancer for urgent investigation. Methods A double-blinded diagnostic accuracy study was conducted in 50 hospitals in England between October 2017 and December 2019. Patient...

Anal Squamous Cell Carcinoma (ASCC) is a rare cancer that has a rapidly increasing incidence in areas with highly developed economies. ASCC is strongly associated with HIV and there appears to be increasing numbers of younger male persons living with HIV (PLWH) diagnosed with ASCC in Greater London. This is a retrospective cohort study of HIV posit...

Background There is strong evidence suggesting that excessive fat distribution, for example, in the bowel mesentery or a reduction in lean body mass (sarcopenia) can influence short-, mid-, and long-term outcomes from patients undergoing various types of surgery. Body composition (BC) analysis aims to measure and quantify this into a parameter that...

Objective To assess whether a faecal immunochemical test (FIT) could be used to select patients with suspected colorectal cancer (CRC) symptoms for urgent investigation. Design Multicentre, double-blinded diagnostic accuracy study in 50 National Health Service (NHS) hospitals across England between October 2017 and December 2019. Patients referred...

Introduction COVID-19 has had an impact on the provision of colorectal cancer care. The aim of the CRC COVID study is to describe the changes in colorectal cancer services in the UK and USA in response to the pandemic and to understand the long-term impact. Methods and analysis This study comprises 4 phases. Phase 1 is a survey of colorectal units...

Aim: To assess the benefit of adjuvant chemotherapy in high-risk stage II colorectal cancer. Method: A systematic literature review and meta-analysis was performed comparing survival in patients with resected stage II colorectal cancer and high-risk features having postoperative chemotherapy versus no chemotherapy. Results: Of 1031 articles sc...

Background: Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods...

Background Overall survival from rectal cancer has almost doubled over the last 20 years. Following recommendations in management guidelines plays some part in this, but the extent of discrepancies between them has not been evaluated. Methods National Comprehensive Cancer Network (NCCN, USA), European Society for Medical Oncology (ESMO, Europe) an...

Mixed adenoneuroendocrine carcinoma (MANEC) are rare cancers of the gastrointestinal (GI) and pancreatobiliary tract. They are characterized by the presence of a combination of epithelial and neuroendocrine elements, where each component represents at least 30% of the tumour. Review of literature and consolidation of clinicopathological data. Sixty...

Background: Appendicitis is the most common abdominal surgical emergency worldwide. Differences between high- and low-income settings in the availability of laparoscopic appendectomy, alternative management choices, and outcomes are poorly described. The aim was to identify variation in surgical management and outcomes of appendicitis within low-,...

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort stu...

Background: Guidelines are important to standardize treatments and optimize outcomes. Several societies have published authoritative guidelines for patients with colon cancer, and a certain degree of variation can be predicted. Objective: This study aims to compare Western and Asian guidelines for the management of colon cancer. Data sources:...

Introduction: Surgical site infection (SSI) is a well-known complication of colorectal surgery associated with increased morbidity and hospital stay. Antimicrobial prophylaxis can reduce the risk of SSI by as much as 75%. Extended-spectrum β-lactamase (ESBL)-producing pathogens make the successful use of such prophylaxis a challenge and are a real...

Aim Social media (SM) can provide information and medical knowledge to patients. Our aim was to review the literature and web-based content on SM that is used by Colorectal Cancer (CRC) patients, as well as surgeons’ interaction with SM. Method Studies published between 2006 and 2016 were assessed. We also assessed the impact of several hashtags o...

PRISMA checklist for the systematic review. (DOC)

The number of permanent colostomies carried out in the United Kingdom is approximately 6400 per year1. Stomal prolapse is a known complication of colostomy formation. We presented the first case of small bowel herniation into a healthy stomal prolapse with subsequent ischaemia of the herniated bowel in a 102-year-old patient. This rare sequela of a...

Background: Colorectal Cancer (CRC) is a disease of the elderly, and with an ageing population, oncological surgical procedures for CRC in the elderly is expected to increase. However, the balance between surgical benefits and risks associated with age and comorbidities in elderly patients is obscure. Materials and methods: A retrospective database...

Purpose: Female patients with pelvic floor diseases may suffer from several sexual disorders and sexual life impairments. The aim of this manuscript was to evaluate sexual dysfunction in female patients presenting with faecal incontinence (FI) and defecation disorder (DD). Methods: A retrospective review was performed of a prospectively collecte...

The aim of this study was to identify the mode of presentation and incidence of colorectal cancer in pregnancy (CRC-p), assess the outcomes of the mother and foetus according to gestational age, treatment delivered and cancer features and location. A systematic review of the literature was carried out to identify studies reporting on CRC-p and pool...

Traditionally few students have had the opportunity to contribute to high-quality clinical research. Over the last five years, collaborative networks have empowered students and trainees to participate in high-impact multicentre studies that have potential to change clinical practice and improve patient care. The UK Foundation Programme Application...

Background Surgical mortality data are collected routinely in high-income countries, yet virtually no low- or middle-income countries have outcome surveillance in place. The aim was prospectively to collect worldwide mortality data following emergency abdominal surgery, comparing findings across countries with a low, middle or high Human Developmen...

Dear Editor-in-Chief, We were interested to read the recent publication from St. Mark’s Hospital, London, concerning extended lateral pelvic side wall excision (‘ELSiE’) for locally advanced or recurrent anorectal cancer extending out through the greater sciatic foramen [1]. The authors report achieving an R0 resection in all six patients, somethin...

It is increasingly recognised that leadership skills are a key requirement in being successful in surgery, regardless of speciality and at all levels of experience and seniority. Where the emphasis was previously on technical ability, knowledge and diagnostic acumen, we now know that non-technical skills such as communication and leadership contrib...

This article aims to review teamwork and the creation of effective teams within healthcare. By combining research material found in management, psychology and health services research the article explores the drivers increasing the importance of teamwork, reviews the current knowledge base on how to build a team and focuses on some of the barriers...

Background: Diagnosis of acute appendicitis is difficult, particularly in paediatric patients, where clinical signs maybe harder to elicit. Traditionally, history and clinical signs combined with white cell count (WCC) have been used in its diagnosis. Over recent years, C-reactive protein (CRP) is also being measured routinely.

Background: Diagnosis of acute appendicitis is difficult, particularly in paediatric patients, where clinical signs maybe harder to elicit. Traditionally, history and clinical signs combined with white cell count (WCC) have been used in its diagnosis. Over recent years, C-reactive protein (CRP) is also being measured routinely.

This report discusses a case in which a 21-year-old pregnant woman had a levonorgestrel intrauterine system (LNG-IUS) located in the Pouch of Douglas. Vaginal removal of the LNG-IUS was not possible and the subsequent delivery was uneventful. Five months after birth the LNG-IUS was removed laparoscopically after careful adhesiolysis with cutting di...

In the past, surgical training has been based on traditional apprenticeship model of mentoring. To cope with the rapidly changing environment of modern surgery, the mentoring process may require significant modernization. Literature for this review was identified by searching for the MeSH heading ‘mentors’ in Ovid MEDLINE, EMBASE, PsycINFO and Coch...

Mentoring programmes help to facilitate the process of continuous professional development in surgery, providing an organizational structure around a mentor-mentee relationship which helps to develop the mentee. The lack of guidelines outlining how to set up such mentoring programmes, the fragmented inter-relationships of existing schemes and the l...

Miniaturized extracorporeal circulation (mECC) attempts to reduce the adverse effects of conventional extracorporeal circulation (CECC) bypass. However, the potential benefits remain unclear and safety concerns persist. A systematic literature review identified 29 studies incorporating 2,355 patients: 1,181 (50.1%) who underwent cardiac surgery wit...

Emma Stanton and Oliver Warren look at initiatives around the country for junior doctors to develop leadership skills

Leadership is not formally taught at any level in surgical training; there are no mandatory leadership courses or qualifications for trainees or specialists, and leadership performance is rarely evaluated within surgical appraisal or assessment programmes. Literature obtained from a MEDLINE search was reviewed to determine the characteristics of su...

Good medical leadership is vital in delivering high-quality healthcare, and yet medical career progression has traditionally seen leadership lack credence in comparison with technical and academic ability. Individual standards have varied, leading to variations in the quality of medical leadership between different organisations and, on occasions,...

Recognition of the adverse effects of conventional extracorporeal circulation (CECC) led to the development of alternative technologies and techniques to minimize their impact while maintaining circulation during coronary artery bypass grafting (CABG). Off-pump coronary artery bypass (OPCAB) grafting has become established as one such alternative a...

In an attempt to reduce the negative sequelae of cardiopulmonary bypass (CPB), a variety of new technologies have been created. This study investigates variations in the application of these technologies throughout Great Britain and Ireland (GB & I). All perfusion departments within GB & I were surveyed about equipment and technologies used in CPB....

Thoraco-abdominal aortic aneurysm repair remains a formidable challenge to vascular surgeons. The traditional repair of thoraco-laparotomy with aortic cross-clamping is associated with a high morbidity and mortality despite significant advances in perioperative critical care, anaesthetic and surgical techniques. The advent of the endovascular revol...

Currently, a significant amount of surgeons' personal development occurs passively and informally, predominantly through role modelling and mentoring provided by senior colleagues. However, these traditional mentor-mentee relationships are being eroded by increased clinical, research and administrative demands and the modernisation of surgical care...

Academic surgical departments are required to perform three key roles; provision of highly specialized clinical care, high-quality undergraduate and postgraduate education to create the next generation of surgeons and delivery of excellent, innovative research. To ensure that these commitments are delivered requires clinical and academic excellence...

Postoperative hemorrhage is a recognized complication of pediatric cardiac surgery. Both the immature coagulation system and increased susceptibility to hemodilution increase the likelihood of pediatric patients developing coagulopathy when compared with adult counterparts. Treatment options remain limited. Recombinant factor VII (rFVIIa) is a hemo...

I am a first-year general surgery registrar in North West Thames. In February 2008 I completed a two-year MD at Imperial College London. Prior to returning to full-time clinical work, Professor the Lord Darzi of Denham offered me the opportunity to be seconded to the Department of Health (DH) for eight months, to be his clinical advisor. With his g...

Intestinal ischemia/reperfusion (I/R) injury initiates a systemic inflammatory response syndrome with a high associated mortality rate. Early diagnosis is essential for reducing surgical mortality, yet current clinical biomarkers are insufficient. Metabonomics is a novel strategy for studying intestinal I/R, which may be used as part of a systems a...

Training in surgical disciplines in the United Kingdom has undergone tremendous change over the past two decades. The introduction of specialist training programmes, working time directives, quality ratings and a drive toward ambulatory and minimal access surgery have led to challenges with respect to training and service commitments of healthcare...

'Prepare to Lead' is a leadership development mentoring programme for specialist and GP registrars which aims to develop a cohort of future clinical leaders for the NHS in London. This article describes the process by which this innovative scheme was established and delivered and reflects on the first year of the scheme and our learning during this...

Off-pump coronary artery bypass (OPCAB) surgery in patients with left main stem (LMS) disease remains controversial. This meta-analysis compares early outcomes of OPCAB surgery with on-pump coronary artery bypass (ONCAB) surgery in patients with significant LMS disease, focusing on the outcomes stroke and transient ischemic attack (TIA). This is a...

Screening X-ray mammography is limited by false positives and negatives leading to unnecessary physical and psychological morbidity. Diffuse Optical Imaging using harmless near infra red light, provides lesion detection based on functional abnormalities and represents a novel diagnostic arm that could complement traditional mammography. Reviews of...

The aim of a surgical residency program is to produce competent professionals displaying the cognitive, technical, and personal skills required to meet the needs of society. Current changes to the delivery of healthcare necessitate the development of new models of training. These can be supported with the development of new technologies to train an...

Post-operative haemorrhage is a recognised complication and independent predictor of outcome in complex vascular surgery. The off-license administration of activated Recombinant Factor VII (rFVIIa) to treat haemorrhage in other surgical settings has been investigated, but concerns over potential adverse events have limited its use in vascular surge...

Neurocognitive enhancement is a rapidly expanding scientific field. The vast ethical implications of this developing field for surgical practice have yet to be considered within the literature. This article outlines the reasons surgeons may, in the near future, consider using neurocognitive enhancement and addresses the resulting significant ethica...

Pulmonary injury mediated by activated leukocytes is a recognized complication of cardiopulmonary bypass. The aim of this paper is to systematically analyze the effects of systemic leukofiltration within the cardiopulmonary bypass circuit on pulmonary injury and related clinical outcomes. We performed a systematic search to identify randomized cont...

Cardiopulmonary bypass causes a systemic inflammatory reaction. Activation of leukocytes is an important part of this process, and is known to directly contribute to the development of postoperative coagulopathy, and thus hemorrhage. The removal of leukocytes from the cardiopulmonary bypass circulation, using specialized filters, has been proposed...