Intraductal papillary mucinous neoplasms or tumours (IPMNs or IMPTs) are cystic tumours of the pancreas.
These tumours are most frequently identified in older patients (50-60 years of age) 6. Main duct type (see below) appears to present a decade or so earlier on average than bran...
Intramural bowel gas, also known as pneumatosis intestinalis, refers to the clinical or radiologically finding of gas within the wall of the bowel.
There are different terminologies in the medical literature, such as pneumatosis intestinalis, pneumatosis coli, and pneumatosis cysto...
Intraperitoneal focal fat infarction (IFFI) refers to a group of self-limiting abdominal diseases where the primary insult is acute inflammation of intraperitoneal fat. They commonly mimic the more common causes of acute abdomen such as acute diverticulitis and acute appendicitis. The group incl...
Intussusception occurs when one segment of bowel is pulled into itself or a neighbouring loop of bowel by peristalsis. It is also known as bowel telescoping into itself.
It is an important cause of an acute abdomen in children and merits timely ultrasound examination and reduction to preclude s...
The inverted "V" sign, also known as lateral umbilical ligament sign, is a sign of pneumoperitoneum manifested by visualization inverted "V" shape in the pelvis on supine view of abdominal radiographs. It represent free air outlining the lateral umbilical ligaments. In infants, the lateral umbi...
Investigating abdominal pain is a common request from clinical teams throughout most hospitals. Causes of abdominal pain are vast and as such, appropriate history and examination are necessary to initiate appropriate initial management and determine appropriate investigations.
Investigation of jaundice is heavily reliant on radiology, from the simplest of investigations (the ultrasound) through to much more complicated MRI-based test and intervention.
It is important to determine whether jaundice is pre-hepatic, intra-hepatic or post-hepatic. Many of the tests that a...
Nausea and vomiting (often abbreviated in medical notes to N&V) are non-specific physical manifestations of disease. They may occur together, or in isolation and may be the result of obstructive pathology or as a general manifestation of systemic disease. As such, radiological investigation must...
Investigating PR bleeding radiologically may help to make a diagnosis or give more information after a diagnosis has been established. Radiology should not replace appropriate physical examination or appropriate use of sigmoidoscopy and colonoscopy.
This is a summary article;...
Iron deficiency anaemia is a common cause of anaemia and a common precipitant to radiological investigation.
Amongst men and postmenopausal women, the incidence in the developed world is around 2%. Among premenopausal women, the incidence is greater and in most cases, investigatio...
Ischaemic colitis refers to inflammation of the colon secondary to vascular insufficiency and ischaemia. It is sometimes considered under the same spectrum as intestinal ischaemia. The severity and consequences of the disease are highly variable.
Ischaemic bowel is typically a dis...
The ischioanal (or ischiorectal) fossa is a fat-filled space of the perineum.
The ischioanal fossa is a paired triangular-shaped space lateral to the anal canal with an apex directed anteromedially towards the pubic symphysis. Each ischioanal fossa is separated from the other by...
Ishikawa classification system describes the degree of involvement of adjacent portal vein and SMV by pancreatic ductal adenocarcinoma based on calibre of the vein:
type I: normal
type II: smooth shift/displacement with normal calibre
type III: unilateral narrowing
type IV: bilateral nar...
Isolated free fluid in trauma may or may not represent a significant injury, and this creates a diagnostic dilemma in determining appropriate treatment for these patients.
The presence of isolated free fluid in trauma occurs in 3-5% of blunt trauma patients 1-4.
Ivor Lewis procedure (also known as a gastric pull-up) is a type of oesophagectomy, an upper gastrointestinal tract operation performed for mid and distal oesophageal pathology, usually oesophageal cancer.
Due to the necessity of removing a significant length of the oesophagus, the stomach is "...
The jejunal and ilieal branches of the superior mesenteric artery are variable in number.
The pass in the two layers of the mesentery to the jejunum and ileum and progressively divide and join in a series of anastomosing arcades. From the arcades, straight arteries (also known as vasa recta) pa...
Jejunal atresia is a congenital anomaly characterised by obliteration of the lumen of the jejunum. The site of the atresia can be anywhere from the ligament of Treitz to the jejunoileal junction. There can be more than one atretic segment.
This article will focus on jejunal atresia alone but be...
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 coeliac 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 ...
The jejunum is arbitrarily defined as the proximal two-fifths of the small intestine and is, on average, ~300 cm in length.
The primary method of evaluation of the small bowel is small bowel follow-through examination (SBFT). On SBFT, the jejunum has a delicate feathery appearanc...
There are a few differences that can help differentiate jejunum and ileum 1-3:
jejunum is slightly wider (< 3 cm) than ileum (<2 cm)
jejunum folds (valvulae conniventes) are thicker (2-3 mm) than ileum folds (1-2 mm)
jejunum folds are also more numerous and deeper than ileum folds
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 oesophageal 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 semi-circular zone surrounding the elevated ridge of the ulcer. This complex is seen in cases of gastric adenocarcinoma on barium studies.
Carman meniscus sign
The Kirklin sign refers to a deformity of the normal gastric air 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 tumour (G...
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...
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 caecum to peritoneum and liver, crossing the duodenum in their course. Extension, however, can in...
Lane-Hamilton syndrome (LHS) refers to the rare concurrent association of idiopathic pulmonary haemosiderosis and coeliac 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 ...
Langerhans cell histiocytosis (LCH) is a rare multi-system disease with a wide and heterogeneous clinical spectrum and variable extent of involvement.
The disease is more common in the paediatric population, with a peak incidence between one and three years of age 5. Incidence is...
Large bowel (colorectal) lymphoma is a very rare tumour, 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) are 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 onl...
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 prompt diagnosis and treatment.
This is a summary articl...
The large intestine (or large bowel) is a 1.5 metre muscular tube that extends from the caecum 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 in...
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 late...
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...
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 coeliac artery.
It passes superiorly, giving off an
oesophageal branch to the distal oesophagus, then enters the lesser omentum to
pass along the lesser curvature of the stomach. Anastomoses along the lesser curvature with the...
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 oesophageal ...
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 subphrenic space is a subcompartment of the 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
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 tumour and account for ~8% of malignant soft tissue tumours 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 faecal evacuation as well as maintaining continence.
The levator ani has three main compon...
Li-Fraumeni syndrome is a hereditary cancer syndrome due to mutations in the tumour suppressor gene TP53. Approximately half of affected individuals are thought to develop invasive cancer by 30 years of age 1.
The ligamentum venosum is a fibrous remnant which travels superiorly from porta hepatis to the liver and then reaches the inferior vena cava. It is often obliterated in adults.
In the fetus, it is patent and known as ductus venosus, shunting blood from the umbilical vein to inferior vena cava ...
The light bulb sign of an adrenal pheochromocytoma is MRI feature of this tumour. This refers to marked hyperintensity seen on T2 weighted sequences however this finding is neither sensitive nor specific and pheochromocytomas are more often heterogeneous with intermediate or high T2 signal inten...
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 (see: linitis plastica of the rectum). The appearance is said to be reminiscent of an old leather water-bottle.
The underlying cause is usuall...
Lipomas are benign tumours composed of mature adipocytes. They are the most common soft tissue tumour, seen in ~2% of the population.
Patients typically present in adulthood (5th-7th decades).
Typically lipomas are subcutaneous in location and present in a...
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 ileocaecal 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.
Littoral cell angioma of the spleen (LCA) is a rare and relatively recently (1991) described vascular tumour 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's diverticulum. Also known as a persistent omphalomesenteric duct hernia. It is most frequently encountered in the inguinal region.
blind ending tubular structure arising from antimesentric border of small bowel and extend...
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 very few organs that has the ability to regen...
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)
low attenuation lymphadenopathy
high attenuation lymphadenoapthy
Low-grade appendiceal mucinous neoplasms (LAMN), previously known as appendiceal mucinous cystadenomas, are rare mucinous tumours of the appendix showing low-grade cytologic atypia, c.f. high-grade appendiceal mucinous neoplasms.
Considerable controversy still exists on mucinous n...
Causes of calcifications in the lower abdomen and pelvis include:
seminal vesicle and ductus deferens calcification
dropped stones following chol...
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 haematochezia (bright red blood/clots or burgundy stools) or melaena.
The incidence of LGIB is only o...
Lower gastrointestinal bleeding usually occurs distal to the ligament of Treitz.
Presents with melaena, haematochezia or, if subclinical slow bleeding, chronic anaemia.
The lucent liver sign is represented by a reduction of hepatic radiodensity on supine radiograph when there is a collection of free intraperitoneal air 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...
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...
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.
This is a summary article; we do not have a more in-depth reference...
Malignant oesophageal neoplasms are much more common than benign oesophageal neoplasms, especially if the patient is symptomatic.
oesophageal carcinoma (90%)
oesophageal squamous cell carcinoma (SCC)
oesophageal 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 oesophagus, which results in mucosal and submucosal tear with involvement of the venous plexus.
Patients present with massive painless haematemesis.
Tears most commonly ...
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 vascularisation, 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).
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's point is defined as a point that lies one-third of 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's point is relevant for the elicitation...
The McKeown procedure ("tri-incisional oesophagectomy") is a type of oesophagectomy, that is similar in concept to an Ivor Lewis procedure, but it tends to be used for oesophageal lesions that are higher in the oesophagus.
stomach mobilized, the oesophagus
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 Me...
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 ...
Mediastinal pseudocyst is the extension of pancreatic pseudocyst into the the posterior mediastinum through oesophageal or aortic hiatus or rarely through 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 oesophagus or diffuse oesophageal dilatation can be caused by a variety of conditions.
Some of the more common causes are given below 1-3:
malignant stricture, e.g. oesophageal canc...
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.