Jejunocolic bypass was an early form of bariatric surgery. It is no longer performed due to severe side effects.
For this bypass, the proximal small bowel (jejunum) is transected and anastomosed to the colon (such as the transverse colon). The other end of the small bowel is closed and the dist...
Jejunoileal bypass is an older form of bariatric surgery that was developed to be an improvement on jejunocolic bypass. It is no longer performed due to severe side effects.
For this bypass, the proximal small bowel (jejunum) is divided ~35 cm past the ligament of Treitz, and the proximal end i...
Jejunoileal diverticula, also referred to as jejunal diverticula or diverticulosis as most of the diverticula are located in the jejunum, are outpouchings from the jejunal and ileal wall on their mesenteric border that represent mucosal herniation through sites of wall weakening 1.
Jejunoileal fold pattern reversal (a.k.a. jejunisation of the ileum) is one of the signs of celiac disease, and is seen on small bowel follow-through studies as well as CT. The pattern is one of increased number of ileal folds and reduced number of jejunal folds 1,2, and is considered positive w...
The jejunum is arbitrarily defined as the proximal two-fifths of the small intestine and is, on average, about 3 m in length.
Compared to the ileum, the jejunum has more valvulae conniventes and fewer folds per unit length. Like the ileum, the normal jejunal wall thickness is les...
There are a few differences that can help differentiate jejunum and ileum 1-3:
jejunum: upper left part of the peritoneal cavity
ileum: lower right part of the peritoneal cavity
jejunum: greater caliber (<3 cm), thicker walls and more vascular
ileum: lesser calib...
Juvenile polyposis syndrome, also referred as familial juvenile polyposis, is one of the polyposis syndromes and consists of hundreds of juvenile polyps.
Presentation in the second decade is most common 2.
Rectal bleeding, bowel obstruction and intussuscept...
The Kikuchi level is a histopathological term used for describing the degree of infiltration of a sessile early invasive colorectal cancer1. Preoperative assessment of the level of invasion using this classification may decrease the incidence of unnecessary surgery for sessile polyps.
Killian-Jamieson diverticula are esophageal diverticula. Like the more common Zenker diverticulum, it is a false diverticulum and represents an outpouching of mucosa through a muscular defect, in this case Killian's dehiscence.
They are located just below the cricopharyngeal muscle,...
The Kirklin complex is a combination of the Carman meniscus sign associated with a radiolucent semicircular zone surrounding the elevated ridge of the ulcer. This complex is seen in cases of gastric adenocarcinoma on barium studies.
History and etymology
Byrl Raymond Kirklin, (1888-1957 2) an ...
The Kirklin sign refers to a deformity of the normal gastric bubble on an upright chest radiograph due to a mass lesion of the gastric cardia or fundus.
The differential for a Kirklin sign includes:
gastrointestinal stromal tumor (GIST)
Kommerell diverticula occur in some anomalies of the aortic arch system. It usually refers to the bulbous configuration of the origin of an aberrant left subclavian artery in the setting of a right-sided aortic arch. However, it was originally described as a diverticular outpouching at the origi...
The Krenning score is a proposed semi-quantitative method of assessing the degree of tracer uptake on octreotide scintigraphy.
Initially designed for assessment of 111In-DTPA on planar imaging, the Krenning score is applicable to SPECT or SPECT/CT using various radiopharmaceuticals....
This article lists a series of labelled imaging anatomy cases by system and modality.
CT head: non-contrast axial
CT head: non-contrast coronal
CT head: non-contrast sagittal
CT head: angiogram axial
CT head: angiogram coronal
CT head: angiogram sagittal
MR head: T2 axial
Ladd bands are the most commonly encountered form of peritoneal bands in disarrangement of intestines, e.g. intestinal malrotation.
Classically they extend from the abnormally positioned cecum to peritoneum and liver, crossing the duodenum in their course. Extension, however, can inc...
Lane-Hamilton syndrome (LHS) refers to the rare concurrent association of idiopathic pulmonary hemosiderosis and celiac disease 1.
It is typically seen in children under the age of 15 but can occasionally be seen in adults.
History and etymology
It was originally described by D ...
Langerhans cell histiocytosis (LCH) is a rare multi-system disease with a wide and heterogeneous clinical spectrum and variable extent of involvement.
Langerhans cell histiocytosis was previously known as histiocytosis X. The newer term is preferred as it's more descriptive of its...
Large bowel (colorectal) lymphoma is a very rare tumor, accounting for <0.5% of primary colorectal malignancies, ~1.5% of all lymphomas, and ~15% of gastrointestinal lymphoma. Large bowel lymphoma differs from gastric and small bowel lymphoma in clinical presentation, management and prognosis.
Large bowel obstruction (LBO) is often impressive on imaging, on account of the ability of the large bowel to massively distend. This condition requires prompt diagnosis and treatment.
Large bowel obstructions are far less common than small bowel obstructions, accounting for only...
This is a basic article for medical students and other non-radiologists
Large bowel obstruction (LBO) occurs when there is mechanical obstruction of the large bowel and is often impressive on imaging on account of the ability of the large bowel to massively distend. This condition requires prom...
The large intestine (or large bowel) is a 1.5 meter muscular tube that extends from the cecum to the rectum. It has three outer longitudinal muscular layers called taenia coli, which are about 30 cm shorter than the length of the large bowel causing characteristic sacculations interrupted by inc...
The lateral crescent sign is a useful diagnostic sign of a direct inguinal hernia on CT scan, the hernia causing compression and lateral displacement of the inguinal canal contents (ductus deferens, testicular vessels, fat, etc.) to form a semicircle of tissue that resembles a moon crescent seen...
The lateral fossae are concave depressions of peritoneum in the paravesical space that lie between the lateral umbilical folds and the lateral parietal peritoneum. The lateral fossae are the smallest of the anterior paravesical fossae, and typically partially contain the cecum and/or sigmoid col...
The lateral umbilical folds are raised ridges of parietal peritoneum in the deep aspect of the anterior abdominal wall overlying the inferior epigastric vessels. The paired folds originate medial to the deep inguinal ring and end at the arcuate line on the posterior aspect of the anterior abdomi...
The lead pipe appearance of colon is the classical barium enema finding in chronic ulcerative colitis. There is complete loss of haustral markings in the diseased section of colon, and the organ appears smooth-walled and cylindrical.
The left colic artery is the first branch of the inferior mesenteric artery.
It ascends retroperitoneally, dividing into two branches:
passes anteriorly to the left kidney, then enters the
transverse mesocolon, and passes superiorly to supply the upper part of the...
Left colic flexure (or splenic flexure) is the bend in the large intestine in the left upper quadrant of the abdomen as the transverse colon continues as the descending colon. The phrenicocolic ligament attaches the the splenic flexure to the left hemidiaphragm. It lies more cranial than the rig...
The left gastric artery is the smallest and first branch of the celiac artery.
It passes superiorly over the left crus of the diaphragm, approaching the esophageal opening of the diaphragm, giving off an esophageal branch to the distal esophagus, then enters the lesser omentum to pass along t...
The left gastric vein (also known as the coronary vein) drains both gastric walls. It forms a loop with the right gastric vein at the lesser curvature of the stomach. The left gastric vein travels in the lesser omentum to drain in the portal vein. It also communicates with the lower esophageal v...
The left gastroepiploic artery (LGA) is one of the branches of the splenic artery.
The LGA runs within the two layers of the greater omentum to the right along the greater curvature of the stomach, approximately 1 cm from the gastric wall before it anastomoses with the ri...
The left perihepatic space (also known as the left subhepatic space) is a potential space located between the stomach and the visceral surface of left lobe of the liver.
The left perihepatic space can be further subdivided into anterior and posterior spaces. It is a subcompartmen...
The left subphrenic space is a subcompartment of the left supramesocolic space located between the diaphragm and the superior surface of the left lobe of liver.
It is described to have anterior and posterior parts without clear delineation1.
medially: falciform ligament
The left supramesocolic space is an arbitrary subdivision of the supramesocolic space, which lies between the diaphragm and the transverse colon 1,2.
The left supramesocolic space is separated from the right supramesocolic space by the falciform ligament 3. The left supramesocoli...
Leiomyosarcomas (LMS) are extremely rare malignant neoplasms that originate from smooth muscle cells and may be considered the malignant counterpart of a leiomyoma. They are classified as a soft tissue tumor and account for ~8% of malignant soft tissue tumors 10.
Lemmel syndrome is defined as an obstructive jaundice caused by a periampullary duodenal diverticulum (of the second part of the duodenum) compressing the intrapancreatic part of the common bile duct with resultant upstream dilatation of the extra- and intrahepatic bile ducts.
The lesser sac or omental bursa is a potential peritoneal space within abdomen, part of the peritoneal cavity. It may be conceptualized as the space posterior to the lesser omentum, between the posterior wall of the stomach and surface of peritoneum which covers the anterior surface of the left ...
Lesser sac hernias are a type of internal hernia, where abdominal contents protrude through the foramen of Winslow, hence they are also known as foramen of Winslow hernia.
Lesser sac hernias are rare, accounting for <0.1% of abdominal hernias and 8% of internal hernias 1,2.
The levator ani, also known as the muscular pelvic diaphragm, is the musculotendinous sheet that forms the majority of the pelvic floor, supports the pelvic viscera, and aids in urinary and fecal evacuation as well as maintaining continence.
The levator ani has three main compone...
Levator ani syndrome (LAS) is a musculoskeletal pain syndrome involving the pelvic floor, thought to be caused by spasm or scarring of the levator ani muscles.
Levator ani syndrome is characterized by recurrent pain, pressure or discomfort in the region of the rectum, sac...
Li-Fraumeni syndrome is a hereditary cancer syndrome due to mutations in the tumor suppressor gene TP53. Approximately half of affected individuals are thought to develop invasive cancer by 30 years of age 1.
The ligament of Treitz, also known as the suspensory ligament of the duodenum, is a double fold of peritoneum suspending the duodenojejunal flexure from the retroperitoneum.
It is often used interchangeably with duodenojejunal (DF) flexure.
The ligament of Treitz is comprised of two p...
The ligamentum venosum is a fibrous remnant which travels superiorly from the porta hepatis of the liver to the inferior vena cava. It is often obliterated in adults.
In the fetus, it is patent and known as the ductus venosus which shunts blood returning from the placenta in the umbilical vein...
The light bulb sign of an adrenal phaeochromocytoma is an MRI feature of this tumor. It refers to marked hyperintensity on T2 weighted sequences, however, this finding is neither sensitive nor specific and phaeochromocytomas are more often heterogeneous with intermediate or high T2 signal intens...
The line alba (Latin for white line) is a single midline fibrous line in the anterior abdominal wall formed by the median fusion of the layers of the rectus sheath medial to the bilateral rectus abdominis muscles. It attaches to the xiphoid process of the sternum and the pubic symphysis. The umb...
Linitis plastica is a descriptive term usually referring to the appearance of the stomach, although the rectum can also be described this way. The appearance is said to be reminiscent of an old leather water-bottle.
The underlying cause is usually a scirrhous adenocarcinoma with diff...
Lipase, more specifically pancreatic lipase, is an enzyme produced in the pancreas and is responsible for the digestion of fat molecules. It may be raised (hyperlipasaemia) in numerous pancreatic, hepatobiliary and other diseases but is most commonly associated with acute pancreatitis.
Lipomas are benign tumors composed of mature adipocytes. They are the most common soft tissue tumor, seen in ~2% of the population.
Patients typically present in adulthood (5th-7th decades).
Typically lipomas are subcutaneous in location and present in adu...
Lipomatosis is a condition where there is diffuse excessive fat deposition within the body. This can especially affect certain regions.
neck and upper region of trunk
lipomatous hypertrophy of the interatrial septum
lipomatous metaplasia of th...
Lipomatosis of the ileocecal valve is a benign condition usually detected incidentally during investigation of other conditions. However, it may itself cause certain vague abdominal symptoms and may be missed on preliminary ultrasound unless a high level of suspicion is present.
Liposarcomas are malignant tumors of fatty tissue and are the malignant counterpart to a benign lipoma. They are the second commonest type of soft-tissue sarcoma.
Liposarcomas are typically found in adults, typically between the ages of 40 and 60, and are rare in children.
Littoral cell angioma of the spleen (LCA) is a rare and relatively recently (1991) described vascular tumor of the spleen.
Littoral cell angiomas may occur at any age and have no gender predilection.
Typically, patients with littoral cell angioma are found ...
Littre hernia is a hernia containing a Meckel diverticulum. Also known as a persistent omphalomesenteric duct hernia. It is most frequently encountered in the inguinal region.
blind-ending tubular structure arising from antimesenteric border of small bowel and extendi...
The liver is the largest abdominal organ that plays a major role in metabolism and has a number of functions, including glycogen storage, decomposition of red blood cells, plasma protein synthesis, hormone production, and detoxification. It is one of the very few organs that has the ability to r...
The liver overlap sign can be seen in sigmoid volvulus wherein the sigmoid loop is seen, usually on an abdominal radiograph, ascending to the right upper quadrant and projecting over the liver shadow.
In one study of 21 patients with confirmed sigmoid volvulus, the sign was present in 9 patient...
The loop-to-loop colon describes an abnormal colonic course associated with the absence of the left kidney from the renal fossa.
The transverse colon extends to the lateral margin of the abdominal wall and the descending colon courses medially to fill the renal fossa, resulting in a "looped" c...
Low attenuation lymphadenopathy suggests underlying necrosis and can be seen in:
metastatic carcinoma (or lymphoma)
infections (tuberculous or fungal)
inflammatory necrotic disorders (e.g. Kikuchi-Fujimoto disease)
extra adrenal myelolipoma
Causes of calcifications in the lower abdomen and pelvis include:
seminal vesicle and ductus deferens calcification
Lower gastrointestinal bleeding (LGIB) is defined as that occurring distal to the ligament of Treitz (i.e. from the jejunum, ileum, colon, rectum or anus) and presenting as either hematochezia (bright red blood/clots or burgundy stools) or melena.
The incidence of lower gastrointe...
Lower gastrointestinal bleeding usually occurs distal to the ligament of Treitz, and has a wide differential diagnosis:
Low-grade appendiceal mucinous neoplasms (LAMN), previously known as appendiceal mucinous cystadenomas, are rare mucinous tumors of the appendix showing low-grade cytologic atypia, c.f. high-grade appendiceal mucinous neoplasms.
Considerable controversy still exists on mucinous ne...
The lucent liver sign is represented by a reduction of hepatic radiodensity on supine radiograph when there is a collection of free intraperitoneal gas located anterior to the liver.
Lumbar hernias are a rare form of posterior abdominal hernia.
Most common in patients aged between 50 and 70 years with a male predominance 1.
Patients with lumbar hernias can present with a variety of symptoms, including a posterolateral mass, back pain,...
Lymphocele of the thoracic duct (thoracic duct cyst) is usually asymptomatic or less commonly may present as left supraclavicular fossa mass 1.
The clinical significance of a thoracic duct cyst lies in its misidentification as a pathological lesion at radiological assessment, whi...
Macroamylasaemia is the presence of serum amylase of a large molecular size, seen in both otherwise healthy individuals, and also in various diseases. Amylase seems to be able to self-polymerise and/or form complexes with other blood proteins, e.g. immunoglobulins.
Macrolipasaemia is the presence of serum lipase of a large molecular size, seen occasionally in otherwise healthy individuals, but more commonly in various diseases. Lipase is able to self-polymerise and/or form complexes with other blood proteins e.g. immunoglobulins.
The term magenstrasse refers to a tubular portion of the stomach adjacent to the lesser curve of the stomach. It is a favoured route by food, fluids and drugs as they flow from the cardia/fundus to the gastric outlet 1.
Magenstrasse is an old German anatomical term that has come back into commo...
Magnetic resonance cholangiopancreatography (MRCP) is a non-invasive imaging technique to visualize intra and extrahepatic biliary tree and pancreatic ductal system.
It can provide the diagnostic range equivalent to the ERCP and so it can replace the ERCP in high risk patient to avoid significa...
This is a basic article for medical students and other non-radiologists
Malignant biliary tract obstruction (MBTO) represents a group of conditions that cause obstructive jaundice. While most examples are the result of pancreatic head cancers, other malignancies may be causative.
Malignant esophageal neoplasms are much more common than benign esophageal neoplasms, especially if the patient is symptomatic.
esophageal carcinoma (90%)
esophageal squamous cell carcinoma (SCC)
esophageal spindle cell carcinoma
Barium meal has been frequently used to differentiate malignant and benign gastric ulcers:
Features suggesting benign gastric ulcer
outpouching of ulcer crater beyond the gastric contour (exoluminal)
smooth rounded and deep ulcer crater
smooth ulcer mound
smooth gastric folds that reach the...
Mallory-Weiss tears occur due to violent projection of gastric contents against the lower esophagus, which results in mucosal and submucosal tear with involvement of the venous plexus. The resultant clinical syndrome is known as Mallory-Weiss syndrome.
Patients present w...
Malone antegrade continence enema is a surgical procedure where the vermiform appendix or ‘neoappendix’ is used to create a small stoma at the abdominal wall allowing antegrade enemas to be administered to empty the colorectum. This procedure is important particularly in children and adolescents...
The marginal artery of Drummond, also known as the marginal artery of the colon, is a continuous arterial circle or arcade along the inner border of the colon formed by the anastomoses of the terminal branches of the superior mesenteric artery (SMA) and inferior mesenteric artery (IMA).
Remembering the colon vascular supply can be confusing because of inconstant collateral vascularization, therefore mnemonics can be helpful.
One way to remember the location of the marginal artery of Drummond is to remember that it runs distally to the root of the mesentery (near the colon).
The differential diagnosis of a mass in the inguinal region includes:
hydrocele of the canal of Nuck
lymphadenopathy or necrotic lymph node
aneurysm or pseudoaneurysm of the femoral artery
Maydl hernias are defined as the presence of two small bowel loops within a single hernial sac, that is, there are two efferent and two afferent loops of bowel, forming a "W" shape.
This type of hernia is more prone to strangulation and necrosis. The intervening intra-abdominal loop is also at ...
McBurney point is defined as a point that lies one-third of the distance laterally on a line drawn from the umbilicus to the right anterior superior iliac spine. Classically, it corresponds to the location of the base of the appendix 1.
Clinically, McBurney point is relevant for the elicitation...
The McKeown procedure ("tri-incisional esophagectomy") is a type of esophagectomy, that is similar in concept to an Ivor Lewis procedure, but it tends to be used for esophageal lesions that are higher in the esophagus.
stomach mobilized, the esophagus
"gastric tube" may ...
Meandering main pancreatic duct (MMPD) comprises of a reverse Z-type and loop-type of pancreatic ducts.
These ductal variants are found in ERCP and MRCP studies. The exact incidence is not known.
Increased incidence of meandering pancreatic duct has been reported in patients with idiopathic re...
Meckel diverticulitis is the inflammation of Meckel diverticulum, which is the most common congenital structural abnormality of the gastrointestinal tract 3. Despite this, it is an uncommon cause of acute abdomen and is often not correctly diagnosed pre-operatively.
This article focuses on Mec...
Meckel diverticulum is a congenital intestinal diverticulum due to fibrous degeneration of the umbilical end of the omphalomesenteric (vitelline) duct that occurs around the distal ileum. It is considered the most common structural congenital anomaly of the gastrointestinal tract.
Meconium ileus refers to a neonatal bowel obstruction of the distal ileum due to abnormally thick and impacted meconium. Unlike in the meconium plug syndrome, the meconium is abnormal in consistency.
Meconium ileus is more common in white populations and affects both sexes almost ...
Meconium peritonitis refers to a sterile chemical peritonitis due to intra-uterine bowel perforation and spillage of fetal meconium into the fetal peritoneal cavity. It is a common cause of peritoneal calcification.
The estimated prevalence is at ~1 in 35,000.
The medial fossae are concave depressions of peritoneum in the paravesical space bounded by the medial umbilical folds and the lateral umbilical folds. The fossae are contained within the inguinal (Hesselbach’s) triangle. The right medial fossa typically partially contains the cecum and/or ileum...
The medial umbilical folds are raised ridges of parietal peritoneum in the deep aspect of the anterior abdominal wall formed by the underlying medial umbilical ligaments. The paired folds run from pelvis to umbilicus. The medial umbilical ligaments are anatomical remnants of foetal umbilical art...
The median umbilical fold is a raised ridge of parietal peritoneum in the deep aspect of the anterior abdominal wall overlying the median umbilical ligament. It runs from the apex of the bladder to the umbilicus. The median umbilical ligament is the anatomical remnant of the foetal urachus. The ...
A mediastinal pseudocyst is the extension of pancreatic pseudocyst into the posterior mediastinum through esophageal or aortic hiatus or rarely through the foramen of Morgagni. It is a rare complication of acute or chronic pancreatitis.
It can present with symptoms due to...
Medical devices in the abdomen and pelvis are important to be recognised, just like medical devices of the chest. Often we ignore these devices, considering them to be incidental and non-pathological, however it is essential to be aware of potential complications.
Mega esophagus or diffuse esophageal dilatation can be caused by a variety of conditions.
Some of the more common causes are given below 1-3:
malignant stricture, e.g. esophageal cancer, c...
Melioidosis is an infectious disease caused by Burkholderia pseudomallei (previously known as Pseudomonas pseudomallei) and is a multisystem disorder which may affect the lungs, brain, visceral organs, or musculoskeletal system.
Melioidosis is a disease of the monsoon season in th...
Ménétrier disease (MD) is a form of rare idiopathic hypertrophic gastropathy.
Rare disease with incidence < 1 per 200,000. Bimodal in distribution, children often < 10 years; adult forms 30-60 years, peak 55 years. Male preponderance both in juvenile and adult form 7.
In the gallbladder, the Mercedes-Benz sign describes a star-shaped pattern of gas-fissuring within gallstones initially described on an abdominal radiograph 2.
Fissures, usually fluid-filled, are present in close to 50% of gallstones. Less than half of these fissured gallstones contain some amo...
Mesenteric adenitis is a self-limiting inflammatory process that affects the mesenteric lymph nodes in the right lower quadrant, and is clinically often mistaken for acute appendicitis.
Mesenteric adenitis is most common in children and adolescents although it may occasionally aff...