Selected publications from PubMed
Background Trauma remains a major health problem worldwide and, in many countries, it continues to increase. Globally, road traffic injuries are the leading cause of death between the ages of 18 and 29, while, in the United States, trauma is the leading cause of death in young adults and accounts for 10% of all deaths among men and women. Around 45 million people globally suffer moderate to severe disability every year due to trauma. According to the World Health Organization (WHO) trauma is expected to become the third leading cause of disability worldwide by 2030. Traumatic injuries can range from minor isolated wounds to complex injuries involving multiple organ systems. Abdominal injuries, in particular, constitute a significant source of morbimortality in traumatic patients, with up to 15% of all accidents presenting an abdominal injury. The mechanism of injury, injury forces, location of injury, and hemodynamic status of the patient determine the priority and best method of abdominal and pelvic assessment. Of all traumatic abdominal injuries, 75 to 90% of patients with a gunshot wound, 25 to 35% with a stab wound, and 15 to 20% of patients with a blunt trauma will require an emergency laparotomy. What is an emergency laparotomy? The emergency laparotomy, also known as trauma laparotomy, is an emergent procedure performed to treat or control traumatic abdominopelvic injuries. It has some essential parts: – Rapid entry – Adequate (large) incision – Control of massive hemorrhage by: – Packing – Direct control – Proximal + distal control (= source control) – Identification of injuries – Control of contamination – Reconstruction (if possible) Indications – Blunt abdominal trauma with hypotension, with a positive FAST (Focused Assessment with Sonography for Trauma) or clinical evidence of intraperitoneal bleeding, or without another source of bleeding. – Hypotension with an abdominal wound that penetrates the anterior fascia. – Gunshot wounds that traverse the peritoneal cavity. – Evisceration. – Bleeding from the stomach, rectum, or genitourinary tract following penetrating trauma. – Peritonitis. – Free air, retroperitoneal air, or rupture of the hemidiaphragm. – Contrast-enhanced CT that demonstrates ruptured gastrointestinal tract, intraperitoneal bladder injury, renal pedicle injury, or severe visceral parenchymal injury after blunt or penetrating trauma. – Blunt or penetrating abdominal trauma with aspiration of gastrointestinal contents, vegetable fibers, or bile from diagnostic peritoneal lavage, or aspiration of 10 cc or more of blood in hemodynamically abnormal patients. Damage control vs. definitive treatment It is important to appreciate the difference between abdominal surgery as part of the resuscitation process and the definitive surgical treatment for abdominal trauma. Surgical resuscitation includes the “damage control” technique and implies only that the surgical procedure is necessary to save the patient’s life by stopping bleeding and preventing further contamination or injury but is restricted due to the patient’s physiological derangement. By contrast, definitive surgical treatment implies that the physiological state of the patient allows for the definitive surgical repair to take place. Technique All patients undergoing a laparotomy for abdominal trauma should be explored through a long midline incision, made from the xiphoid to the pubis. It is also essential to be able to extend the incision if needed, so patients must have both thorax and abdomen prepared and draped to allow access to the thorax, abdomen and groins if required. Once the abdomen is opened, remove as much blood as possible into a receiver (a sucker may not be enough), eviscerate the small bowel and perform a quick exploration to ascertain if there is an obvious site of large-volume bleeding (where packing is not efficient). Massive hemoperitoneum must be controlled before continuing further with the procedure. Then an absorptive packing with large dry unfolded abdominal swabs must be performed following a clockwise direction: 1.- Under the left diaphragm. 2.- In the left paracolic gutter. 3.- In the pelvis. 4.- In the right paracolic gutter. 5.- Into the subhepatic pouch. 6.- Above and lateral to the liver. 7.- Directly to any other bleeding area (knowing that packing does not control arterial bleeding). After allowing the anesthetist to achieve a correct blood pressure and other vital parameters, the abdominal packs must be removed, one at a time, beginning at the region least likely to be the site of bleeding. In the left upper quadrant, if the spleen seems to be the site of bleeding, a decision needs to be made on whether it should be preserved or removed. Bleeding may be temporarily controlled by placing a vascular clamp across the splenic hilum. In the right upper quadrant, injuries to the liver are assessed. It is recommended to dissect the gastrohepatic ligament to place a vessel loop across the portal triad. – If there is a hepatic hemorrhage and it can be controlled with simple compression, it is most probably venous and may be managed with therapeutic liver packing. – If the bleeding does not cease, a Pringle maneuver should be performed, as the suspicion is an arterial or portal injury. Hepatorrhaphy is then carried out to control intrahepatic vessels, alone or with packing. – If this maneuver fails to control the bleeding, the most likely source are the hepatic veins or the inferior vena cava. If so, compression against the posterior abdominal wall and diaphragm can be successful, and packing should also be performed. An important issue to bear in mind is that lesions must be dealt with in order of lethality: 1.- Injuries to major blood vessels. 2.- Major hemorrhage from a solid abdominal viscera. 3.- Bleeding from mesentery and hollow organs. 4.- Retroperitoneal bleeding. 5.- Contamination. Closure of the abdomen After the procedure, we must adequately prepare for closure. This preparation includes: – Evaluation of the adequacy of hemostasis and/or the need for packing. If a definitive packing may be used, swab packs must be placed flat against the organ and they should exert sufficient force on the organ to tamponade the bleeding. – Abundant lavage and removal of debris in the peritoneal cavity and wound. – Placing drains if required. The choice between primary or delayed closure is based on five principles: 1.- The stability of the patient. 2.- The amount of blood loss. 3.- The volume of intravenous fluid administered. 4.- The degree of intraperitoneal and wound contamination. 5.- The nutritional status and possible intercurrent diseases.
Published
Jan 2021
Hernias are among the oldest recorded illnesses of humankind. About 75% of all hernias appear in the inguinal area. Worldwide, groin hernia repair is one of the most common surgeries, performed on more than 20 million people annually. Inguinal hernias may be classified, in general terms, as indirect, direct and femoral. In day-to-day surgical practice, a classification system for inguinal hernias is infrequently used other than to describe hernia types in general terms. However, a consensus classification system is needed in order to perform research, adapt treatments to hernia types, and carry out quality audits. Several classifications for inguinal hernias have been described to allow surgeons to define the anatomical type of hernia and to match the repair to the defect found. These classifications are based on the size of the hernia and the status of the posterior floor and/or the deep inguinal ring to describe the hernia. Most of them are complex and therefore difficult to remember. Based on the fact that a classification should be simple and educative in order to be adopted by the general surgical community, the European Hernia Society (EHS) proposed a simplified classification for groin hernias. Their proposed classification resembles the Aachen classification. This classification is based on the diameter of the hernia and its position, and 1.5 cm is used as reference for the size of the hernia orifice. In order to further increase simplicity and accuracy, the EHS decided to modify the latter classification only with respect to some minor points, thus preserving the major criteria of the Aachen classification. They suggest the index finger as the reference in open surgery, since the usual size of the tip of the index finger is mostly around 1.5–2 cm. This dimension is also reported to be identical to the length of the branches of a pair of most laparoscopic graspers, dissectors or scissors, enabling the surgeon to use the same classification during laparoscopic surgery. In the EHS classification, the size of the hernia orifice is registered as 1 (1 finger), 2 (1–2 fingers) and 3 (3 fingers). For the anatomic localisation, the same criteria are used as in the Aachen classification (L = lateral, M = medial, F = femoral). For a combined hernia the EHS propose to mention the different hernias in the table by ticking the appropriate box. In addition, the letter P or R can be circled to represent, respectively, a primary or a recurrent hernia.
Published
May 2020
The anterior abdominal wall is a hexagonal area bounded superiorly by the xiphoid process and the costal margins. Inferiorly it extends along the iliac crests and narrows to the superior edge of the pubic bone in the midline. The inferolateral margins are defined by the inguinal ligaments bilaterally. Lateral extension occurs posteriorly to the muscles adjacent to the lumbar spine. The most superficial layers of the abdominal wall are the skin and the subcutaneous tissue. The subcutaneous tissue is comprised of deep and superficial adipose tissue layers separated by fibrous tissue matrices. Camper's fascia is the superficial fatty layer and Scarpa's fascia is a more membranous layer that will eventually become contiguous with the superficial fascia of the back, thorax, and fascia lata of the thigh. The abdominal wall can be divided into midline and anterolateral groups of muscles. The main lateral muscles of the anterior abdominal wall are, from exterior to interior, the external oblique, internal oblique, and transversus abdominis. The rectus abdominis and the pyramidalis muscles comprise the midline group, although the presence of the pyramidalis is not consistent among the population (absent in 15% of individuals). The aponeuroses of the lateral muscles form the sheath of the rectus (anterior and posterior above the arcuate line, and only anterior below) and the linea alba is the midline decussation of the three aponeuroses. The transversalis fascia is a weak fibrous layer covering the inner surface of the transversus abdominis muscles and is separated from the peritoneum by a layer of fat, commonly known as the preperitoneal fat layer. INGUINAL REGION The peculiar anatomy of the inguinal region, characterized by the passage of neurovascular structures from the abdominal cavity to the genital region and the lower limbs, determines the high incidence of herniary pathology at this level. A thorough knowledge of the anatomy of this region is mandatory to properly understand the pathophysiology and treatment of inguinal hernias. Inguinal canal The inguinal canal is an oblique rift approximately 4 to 6 cm long in the lower part of the anterior abdominal wall and it contains the spermatic cord in males and the round ligament of the uterus in females. It is located above the inguinal ligament and between the opening of the external (superficial) and the internal (deep) inguinal rings. The is a triangular opening formed by the medial fibers of the external oblique aponeurosis that lies just lateral to the pubic tubercle. The internal ring is a normal defect in the transversalis fascia shaped like an inverted U. Its arms (anterior and posterior) are a special thickening of the transversalis fascia forming a sling. The boundaries of the inguinal canal are formed by: Superior wall: the arched fibers of the lower edge of the internal oblique muscle and transversus abdominis muscles and their aponeuroses. Inferior wall: the inguinal and lacunar ligaments. Anterior wall: the aponeurosis of the external oblique and, more laterally, by involvement of the internal oblique muscle. Posterior wall (“floor”): it is the most important wall of the inguinal canal. It is formed by fusion of the aponeurosis of the transversus abdominis muscle and the transversalis fascia in 75% of the population (forming a strong wall), and only by the transversalis fascia in the remaining individuals (yielding a weak wall, more prone to hernias). Inguinal ligament The inguinal ligament is the incurved free edge of the external oblique aponeurosis between its origin on the anterior superior iliac spine and its insertion at the pubis. The middle third of the ligament has a free edge and the rest is strongly attached to the iliopsoas fascia. It is important because of its role as both a landmark and an integral component of many groin hernia repairs. The inguinal ligament continues downward to the superior pubic ramus to form the lacunar ligament (Gimbernat’s ligament) and laterally along the pectineal line as the pectineal ligament (Cooper’s ligament). Myopectineal orifice of Fruchard The myopectineal orifice was first described by Fruchard in 1956 and it corresponds to the common locations for rising of all hernias in the inguino-crural region. This area is bounded as follows: Superiorly: arch of the internal oblique muscle and transversus abdominis muscle (transverse arch). Laterally: iliopsoas muscle. Medially: lateral border of the rectus abdominis muscle and its anterior lamina. Inferiorly: Cooper’s ligament. The inguinal ligament bridges and divides this framework into the inguinal region above and the femoral region below. Hesselbach’s triangle The inguinal (Hesselbach) triangle was described by Hesselbach in 1814 and it is formed by the lateral border of rectus abdominis sheath medially, the inferior (deep) epigastric vessels superolaterally, and the inguinal ligament at the base. This area is only covered by the peritoneum and the transversalis fascia, which makes it a weak area and the site of occurrence of direct inguinal hernias. The aponeurotic arch that is formed from the transversus abdominis muscles crosses the apex of this triangle and provides reinforcement for this weak area.
Published
Mar 2020
Background Trauma remains a major health problem worldwide and, in many countries, it continues to increase. Globally, road traffic injuries are the leading cause of death between the ages of 18 and 29, while, in the United States, trauma is the leading cause of death in young adults and accounts for 10% of all deaths among men and women. Around 45 million people globally suffer moderate to severe disability every year due to trauma. According to the World Health Organization (WHO) trauma is expected to become the third leading cause of disability worldwide by 2030. Traumatic injuries can range from minor isolated wounds to complex injuries involving multiple organ systems. Abdominal injuries, in particular, constitute a significant source of morbimortality in traumatic patients, with up to 15% of all accidents presenting an abdominal injury. The mechanism of injury, injury forces, location of injury, and hemodynamic status of the patient determine the priority and best method of abdominal and pelvic assessment. Of all traumatic abdominal injuries, 75 to 90% of patients with a gunshot wound, 25 to 35% with a stab wound, and 15 to 20% of patients with a blunt trauma will require an emergency laparotomy. What is an emergency laparotomy? The emergency laparotomy, also known as trauma laparotomy, is an emergent procedure performed to treat or control traumatic abdominopelvic injuries. It has some essential parts: Rapid entry Adequate (large) incision Control of massive hemorrhage by: Packing Direct control Proximal + distal control (= source control) Identification of injuries Control of contamination Reconstruction (if possible) Indications Blunt abdominal trauma with hypotension, with a positive FAST (Focused Assessment with Sonography for Trauma) or clinical evidence of intraperitoneal bleeding, or without another source of bleeding. Hypotension with an abdominal wound that penetrates the anterior fascia. Gunshot wounds that traverse the peritoneal cavity. Evisceration. Bleeding from the stomach, rectum, or genitourinary tract following penetrating trauma. Peritonitis. Free air, retroperitoneal air, or rupture of the hemidiaphragm. Contrast-enhanced CT that demonstrates ruptured gastrointestinal tract, intraperitoneal bladder injury, renal pedicle injury, or severe visceral parenchymal injury after blunt or penetrating trauma. - Blunt or penetrating abdominal trauma with aspiration of gastrointestinal contents, vegetable fibers, or bile from diagnostic peritoneal lavage, or aspiration of 10 cc or more of blood in hemodynamically abnormal patients. Damage control vs. definitive treatment It is important to appreciate the difference between abdominal surgery as part of the resuscitation process and the definitive surgical treatment for abdominal trauma. Surgical resuscitation includes the “damage control” technique and implies only that the surgical procedure is necessary to save the patient’s life by stopping bleeding and preventing further contamination or injury but is restricted due to the patient’s physiological derangement. By contrast, definitive surgical treatment implies that the physiological state of the patient allows for the definitive surgical repair to take place. Technique All patients undergoing a laparotomy for abdominal trauma should be explored through a long midline incision, made from the xiphoid to the pubis. It is also essential to be able to extend the incision if needed, so patients must have both thorax and abdomen prepared and draped to allow access to the thorax, abdomen and groins if required. Once the abdomen is opened, remove as much blood as possible into a receiver (a sucker may not be enough), eviscerate the small bowel and perform a quick exploration to ascertain if there is an obvious site of large-volume bleeding (where packing is not efficient). Massive hemoperitoneum must be controlled before continuing further with the procedure. Then an absorptive packing with large dry unfolded abdominal swabs must be performed following a clockwise direction: Under the left diaphragm. In the left paracolic gutter. In the pelvis. In the right paracolic gutter. Into the subhepatic pouch. Above and lateral to the liver. Directly to any other bleeding area (knowing that packing does not control arterial bleeding). After allowing the anesthetist to achieve a correct blood pressure and other vital parameters, the abdominal packs must be removed, one at a time, beginning at the region least likely to be the site of bleeding. In the left upper quadrant, if the spleen seems to be the site of bleeding, a decision needs to be made on whether it should be preserved or removed. Bleeding may be temporarily controlled by placing a vascular clamp across the splenic hilum. In the right upper quadrant, injuries to the liver are assessed. It is recommended to dissect the gastrohepatic ligament to place a vessel loop across the portal triad. If there is a hepatic hemorrhage and it can be controlled with simple compression, it is most probably venous and may be managed with therapeutic liver packing. If the bleeding does not cease, a Pringle maneuver should be performed, as the suspicion is an arterial or portal injury. Hepatorrhaphy is then carried out to control intrahepatic vessels, alone or with packing. If this maneuver fails to control the bleeding, the most likely source are the hepatic veins or the inferior vena cava. If so, compression against the posterior abdominal wall and diaphragm can be successful, and packing should also be performed. An important issue to bear in mind is that lesions must be dealt with in order of lethality: Injuries to major blood vessels. Major hemorrhage from a solid abdominal viscera. Bleeding from mesentery and hollow organs. Retroperitoneal bleeding. Contamination. Closure of the abdomen After the procedure, we must adequately prepare for closure. This preparation includes: Evaluation of the adequacy of hemostasis and/or the need for packing. If a definitive packing may be used, swab packs must be placed flat against the organ and they should exert sufficient force on the organ to tamponade the bleeding. Abundant lavage and removal of debris in the peritoneal cavity and wound. Placing drains if required. The choice between primary or delayed closure is based on five principles: The stability of the patient. The amount of blood loss. The volume of intravenous fluid administered. The degree of intraperitoneal and wound contamination. The nutritional status and possible intercurrent diseases.
Published
Jan 2020
Surgical site infection (SSI) can be defined as an infection that occurs in a wound created by an invasive surgical procedure within 30 days from the procedure, or within 90 days if prosthetic material was implanted. This definition includes a wide range of surgical infections, from a superficial infection involving skin only to a more serious one affecting tissues under the skin, organs, or implanted material. SSI is the second most common cause of healthcare-associated infection in Europe and the USA. Although most infections are treatable with antibiotics, SSIs remain a significant cause of morbidity and mortality after surgery. They are estimated to affect 2% to 5% of patients who undergo surgery, and. what is more important, a total of 55% of SSIs are believed to be preventable using evidence-based measures. SSI prevention is not new. Back in the early 19th century, the Hungarian obstetrician Semmelweis was the first to focus on the importance of surgical hand washing before a procedure. He demonstrated a reduction in maternal death from puerperal sepsis through the use of chlorinated hand wash. Lister introduced the use of carbolic acid solution to sterilize surgical instruments and clean wounds. Later, in 1889, the use of surgical gloves in the operating room was introduced by Halsted. Nevertheless, despite the great effort made in the last centuries to prevent SSIs, just a few measures have been scientifically proven. To confront this issue, guidelines have been drafted to standardize the measures and recommendations according to the best available scientific evidence and expert consensus. In this Open Class, we will review two of the main measures to perform during the preoperative period: patient preoperative bathing and surgical hand washing, based on the latest WHO Guidelines. Preoperative bathing This procedure consists in requiring that patients bathe or shower 24 hours before surgery, using either plain or antimicrobial soap. It ensures that the skin is as clean as possible before surgery and reduces the bacterial colonization of the skin, particularly at the site of incision. This measure is a conditional recommendation with a moderate quality of evidence. In general, it is recommended to use an antiseptic soap (like chlorhexidine gluconate), in settings in which it is available and affordable. Nevertheless, as a meta-analysis of nine studies (seven RCTs and two observational studies) that analysed this premise showed, it has not been proved that an antiseptic soap reduces significantly the SSI incidence when compared to plain soap. Three observational studies assessed whether preoperative bathing with chlorhexidine gluconate-impregnated cloths was more effective than using only an antiseptic soap. They showed with just very low quality evidence that using chlorhexidine gluconate cloths was associated with a decrease in SSI compared with no bathing. Surgical hand washing This measure consists in surgical hand preparation either by scrubbing with suitable antimicrobial soap and water or using an alcohol-based hand rub (ABHR) before wearing sterile gloves. Surgical hand washing is vitally important to ensure the least possible contamination of the surgical field. So it is a strong recommendation with moderate quality of evidence. This preventive action is probably the one that has changed the most in recent years. Traditionally, importance has been given to use a scrub brush to friction the skin. However, this practice is currently discouraged because of the skin lesions it causes, and it is only recommended to use it to wash the nails for the first time in the day, or when they are visibly dirty. Alternatively, it is proposed to use a soapy sponge or just the friction made by rubbing hands with an ABHR. When comparing the effect of both different washing techniques, no significant differences have been found between hand rubbing and hand scrubbing in reducing SSI incidence. Take home messages SSI is the second cause of healthcare-associated infection in Europe and the USA. 55% of SSIs are believed to be preventable using evidence-based measures. Preoperative bathing using soap is recommended. There is no evidence that antiseptic soap is better than plain soap. Surgical hand washing with an ABHR or a soapy sponge should be done before any procedure. The use of a scrub brush is discouraged as it causes skin lesions.
Published
Nov 2019
Introduction Neuroendocrine tumors (NETs) are infrequent neoplasms that originate from endocrine glands (parathyroid, pituitary, adrenal glands), from endocrine islets inside other glands (pancreas, thyroid), or from the endocrine cells dispersed throughout the digestive system and the respiratory tract. They can be categorized depending on their origin into foregut (bronchial, gastric, duodenal, and pancreas), midgut (jejunal, ileal, appendiceal, and ascending/transverse colon), and hindgut (distal colon and rectum). A characteristic feature of neuroendocrine cells, and subsequently of tumors derived from them, is the production of a wide range of biogenic amines, peptides, tachykinins, and prostaglandins. These neoplasms that generate an active product are often known by the specific term for each substance, such as for instance, insulinoma, somatostatinoma, glucagonoma, etc. Clinical presentation and diagnosis The excessive production of bioactive substances may determine the clinical presentation of the tumor, with carcinoid syndrome being the most typical and well-known. Carcinoid syndrome consists of a constellation of symptoms, such as episodic flushing, bronchospastic symptoms, secretory diarrhea and associated abdominal pain, due to an increased secretion of serotonin and other agents. This syndrome occurs in the presence of liver metastases as portal circulation enables the liver to clear the hormones before they can enter the systemic circulation. Nevertheless, carcinoid syndrome is relatively uncommon and occurs in only 10 to 20% of patients. The most usual presentations of gastrointestinal NETs are recurrent abdominal pain and cramping, intermittent small bowel obstruction, and gastrointestinal bleeding. However, up to one-third of cases are asymptomatic and are diagnosed by accident. The diagnosis of these tumors includes common forms of anatomic imaging such as computer tomography (CT) and magnetic resonance imaging (MRI) scans, to characterize the extent of the disease and assist with staging and planning therapy, as well as specific functional imaging techniques. These include indium-octreotide scintigraphy (OctreoScan) and PET-CT with 68Ga-DOTATATE. They provide evidence of the biological behavior of the tumor, and are specially recommended for the detection of regional and distant metastases. Other diagnostic methods that must be considered are upper and lower endoscopy, both with standard techniques and with endoscopic ultrasound. Treatment Since they were first labeled as carcinoid tumors by the German pathologist Siegfried Oberndorfer in 1907, there has been significant progress in NET-related biological and clinical research, and consequently, in the treatment options available for these tumors. Nevertheless, surgery remains the only curative method and should be considered for all patients if technically feasible. Specific treatment features by organ of origin Gastric neuroendocrine tumors: Gastric NETs are divided into three categories with different biological behavior and prognoses. Management and treatment depend on the type of gastric NET: Type I includes 70-80% of all gastric NETs. They are associated with chronic hypergastrinemia as a result of chronic atrophic gastritis. The high gastrin levels stimulate neuroendocrine cell hyperplasia in the stomach and induce the development of small, multifocal polypoid NETs. They are well-differentiated tumors and are associated with prolonged survival. The treatment of these tumors is controversial. Generally, for tumors smaller than 1-2 cm, endoscopic resection may be adequate, with endoscopic surveillance every 6-12 months. More aggressive techniques are rarely needed, but they must be considered for tumors larger than 2cm, which increases the risk for metastasis, extensive tumor infiltration of the gastric wall, poorly differentiated histology, and emergent bleeding. Type II includes 5% of gastric NETs, which are also a result of chronic hypergastrinemia. However, the elevated production of gastrin is due to the presence of a gastrinoma (either with Zollinger-Ellison syndrome or MEN 1). In general, they are similar to type I NETs: they are well-differentiated, small and multiple. Therefore, their treatment is also similar. The only difference is that we must first treat the gastrinoma responsible for the disease. Type III are sporadic tumors and include approximately 20% of gastric NETs. They are more aggressive and have a worse prognosis overall. More than 50% present with local or distant metastases at the time of diagnosis. Their treatment is similar to that for standard gastric adenocarcinoma, including partial or total gastrectomy with wide negative margins and a formal lymphadenectomy. Small intestinal neuroendocrine tumors: Small intestinal NETs can occur anywhere from the duodenum to the terminal ileum, but they are most frequently found in the ileum within 60 cm from the ileocecal valve. They can be solitary tumors or multifocal (in 25% of affected patients). These tumors tend to produce both regional and distant metastases (37% and 27% respectively, on presentation), irrespective of size, even if they measure less than 1 cm. The treatment for patients with nonmetastatic tumors consists in resecting the involved segment and its mesentery. The remainder of the small intestine should always be examined properly at the time of surgery, because of the high probability of multifocal tumors. In patients with known metastatic tumors, resection of the primary tumor may be advised in order to reduce the potential of intestinal obstruction or bleeding, and abdominal pain. Nevertheless, this remains a controversial area. Colorrectal neuroendocrine tumors (nonappendiceal): Colonic and rectal NETs are slightly different. Colonic tumors are larger and more aggressive, with at least 40% metastatic tumors on diagnosis. They are most frequently right sided and are usually asymptomatic until they are locally advanced. By contrast, rectal NETs tend to be smaller and are usually localized on presentation. The treatment for colonic NETs is similar to that for colonic adenocarcinomas. A formal partial colectomy and regional lymphadenectomy is recommended, except for small incidentally detected tumors completely removed with an endoscopic polypectomy. In this case, endoscopic surveillance alone can be considered. In the case of rectal tumors, the treatment is similar. If the tumor is smaller than 1 cm and confined to the mucosa or submucosa (and most of them are), an endoscopic resection with negative margins is usually enough. However, tumors larger than 2 cm and those that invade the muscularis propria should be treated with radical surgical resection (low anterior resection or abdominoperineal resection). The treatment for intermediate-sized tumors is controversial. It is generally accepted that tumors without risk factors (elevated mitotic rate, lymphovascular invasion, etc.) can be treated with endoscopic resection, and tumors that show any risk factor should be treated with radical surgery. Appendiceal neuroendocrine tumors: Appendiceal NETs are usually asymptomatic and often detected during an appendicectomy. Their prognosis is best estimated by tumor size. Almost 95% of them are smaller than 2 cm and they have a low probability of having metastases on diagnosis. Appendiceal NETs can be considered cured with only an appendicectomy if they: Are smaller than 1 cm Are confined to the tip of the appendix Do not invade the mesoappendix and have no evidence of lymphovascular invasion Are well differentiated By contrast, a formal right hemicolectomy is advised if the tumor: Is larger than 2 cm Invades the mesoappendix or the appendiceal base Shows lymphovascular invasion Has an intermediate- or high-grade histology. The treatment for tumors between 1 and 2 cm in size is also controversial, and there is no clear evidence about whether or not a right hemicolectomy should be performed.
Published
Oct 2019
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