Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

1,050 results found
Article

Para-oesophageal hernia

Para-oesophageal hernias (POH), or rolling hernias, are an uncommon type of hiatal hernia representing ~10% of all hiatal hernias. The majority of the hiatal hernias being of the sliding type. Clinical presentation Can vary and can include: asymptomatic gastro-oesophageal reflux disease (mai...
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Parastomal hernia

Parastomal hernia is defined as the protrusion of abdominal contents through an abdominal wall defect in the vicinity of the stoma. Classification The hernia may contain a loop of bowel forming the stoma itself, omentum, and/or intestinal loops other than that forming the stoma. Based on the c...
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Parasympathetic pelvic splanchnic nerves

The pelvic splanchnic nerves also known as nervi erigentes are preganglionic (presynaptic) parasympathetic nerve fibres that arise from S2, S3 and S4 nerve roots of the sacral plexus. These nerves form the parasympathetic portion of the autonomic nervous system in the pelvis.   Gross anatomy O...
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Paraumbilical hernia

Paraumbilical hernias are a type of midline ventral abdominal hernia. Pathology Paraumbilica hernias occur near the umbilicus and abdominal contents protrude through a defect in the linea alba and can be quite large. They are usually related to rectus abdominis muscle diastasis.  Differential...
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Paravesical space

The paravesical spaces are paired avascular spaces of the pelvis. The paravesical spaces generally contain fat, but can become filled with ascites, blood, or other substances during pathological processes. Gross anatomy Boundaries superior: lateral umbilical folds inferior: pubocervical fasc...
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Passavant cushion

The Passavant cushion is a small prominence in the posterior pharynx, formed from a focal bulge of the superior pharyngeal constrictor muscles during swallowing. The "cushion" opposes the soft palate during the act of swallowing and is part of the seal between soft palate and pharynx that preve...
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Pathology in general surgery (summary)

Pathology in general surgery is predominantly intra-abdominal and the core set of conditions listed below is a starting point for final-year medical students: bowel perforation acute pancreatitis appendicitis acute cholecystitis diverticulitis intestinal ischaemia colorectal carcinoma ao...
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Pelvic lipomatosis

Pelvic lipomatosis or pelvic fibrolipomatosis represents excessive deposition of fat in pelvis due to overgrowth of adipose cells leading to compression of pelvic organs. Epidemiology The condition usually presents in patients 20-50 years of age. The condition is predominantly (2/3 of cases) s...
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Peptic ulcer disease

Peptic ulcer disease (PUD) encompasses a number of entities, united by the presence of mucosal ulceration secondary to the effects of gastric acid. Since the recognition of Helicobacter pylori as a common causative agent, and the development of powerful anti-acid medications, peptic ulcer diseas...
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Peptic ulcer disease (summary)

This is a basic article for medical students and other non-radiologists Peptic ulcer disease encompasses a number of entities that are the result of gastric mucosal ulceration secondary to the effects of gastric acid. Since the recognition of Helicobacter pylori as a common causative agent and ...
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Percutaneous endoscopic gastrostomy

Percutaneous endoscopic gastrostomy (PEG) is a procedure where a is a flexible feeding tube (commonly known as a PEG tube) is inserted through the abdominal wall and into the stomach. This may be placed under endoscopic or radiological guidance, in the latter, the procedure may be known as a per...
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Perforated appendix

A perforated appendix is one of the complications of acute appendicitis. If appendicitis is left untreated, ischaemic necrosis of a portion of appendiceal wall may occur, leading to perforation. An appendicolith is thought to be associated with a higher probability of perforation 1. Epidemiolog...
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Periampullary tumours

Periampullary tumours are those that arise within 2 cm of the ampulla of Vater in the duodenum. Tumours that fall under this group include four main types of tumours 1,4 that will be approached in their specific articles: pancreatic head/uncinate process tumours: includes pancreatic ductal ade...
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Perianal abscess

Perianal abscess refers to a formed infective-inflammatory collection within the perianal region. It forms part of the broader group of anorectal abscesses. They are often associated with perianal fistulae and are components of grades 2 and 4 fistulae of the St James’ University Hospital classif...
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Perianal fistula

Perianal fistula (or fistula-in-ano) is the presence of a fistulous tract across/between/adjacent to the anal sphincters and is usually an inflammatory condition 4. Epidemiology Incidence is estimated at ~1:10 000 1, with a recognised male predilection of 2-4:1. Associations spontaneous div...
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Pericaecal hernia

Pericaecal hernia is a rare type of internal hernia. Epidemiology It accounts for only 6-13% of internal abdominal hernias. Clinical presentation Clinical symptoms are often characterised by episodes of intense lower abdominal pain, like a colicky right lower quadrant pain very similar to th...
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Perigastric appendagitis

Perigastric appendgitis is a rare inflammatory/ischemic process involving the perigastric ligaments (gastrohepatic, gastrospleic and falciform ligaments). Epiploic appendagitis, greater omental infarction, and perigastric appendagitis have similar mechanisms, clinical presentations, and radiolo...
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Perineal hernia

Perineal hernias are rare pelvic hernias, occurring through a defect in the pelvic floor musculature. Epidemiology More common in females, with peak age of presentation between 40 and 60 years.  Pathology Perineal hernias are classified as anterior or posterior depending on their relationshi...
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Perineal membrane

The perineal membrane is a thin triangular horizontal layer of dense tough fascia in the perineum the dividing the urogenital triangle into the superficial (inferior) and deep (superior) perineal pouches. It attaches to the inferior margins of the ischiopubic rami, enclosing the anterior portio...
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Perineum

The perineum is a diamond shaped region below the pelvic diaphragm and is divided by an imaginary line drawn between the ischial tuberosities into anteriorly the urogenital triangle and posteriorly the anal triangle. Gross anatomy The perineum is bounded by the pubis anteriorly, the ischial tu...
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Peripancreatic pseudoaneurysm

Peripancreatic pseudoaneurysm refers to the formation of a pseudoaneurysm around the pancreatic gland. It is a rare but potentially lethal complication 5. Epidemiology Formation of pseudoaneurysm can occur in as many as 10% of cases of pancreatitis. The time interval is variable, ranging from ...
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Periportal free gas sign

The periportal free gas sign has been described as being strongly suggestive for upper gastrointestinal hollow viscus perforation. See also bowel perforation (summary) pneumoperitoneum
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Perirenal fascia

The perirenal fascia is a dense, elastic connective tissue sheath that envelops each kidney and adrenal gland together with a layer of surrounding perirenal fat forming the perirenal space. It is a multi-laminated structure which is fused posteromedially with the muscular fasciae of the psoas a...
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Perirenal space

The perirenal space is the largest of the three divisions of the retroperitoneum and is the most easily identified. It contains the kidneys, renal vessels and proximal collecting systems, adrenal glands and an adequate amount of fat to allow identification on CT scanning. The space is surrounde...
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Perisplenitis

Perisplenitis is acute inflammation of the splenic capsule and its peritoneal covering. Epidemiology It is seen uncommonly but there is no data on its actual incidence. Clinical Presentation It is seen usually in young and middle-aged patients, with acute left hypochondrial or lower chest pa...
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Peritoneal calcification

Peritoneal calcification is seen in a limited number of conditions that result in calcification of peritoneal structures. Therefore, the differential diagnosis is small: psammoma bodies in malignancy (most frequently cystadenocarcinoma of the ovary): fine sand-like calcification pseudomyxoma p...
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Peritoneal CSF pseudocyst

A peritoneal CSF pseudocyst is a rare complication of ventriculoperitoneal shunt catheter placement. The time from the last shunting procedure to the development of an abdominal pseudocyst ranges from 3 weeks to 5 years.  Pathology The wall is composed of fibrous tissue without an epithelial l...
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Peritoneal hydatidosis

Peritoneal hydatidosis occurs secondary to seeding of echinococcosis to the peritoneum, usually secondary to rupture of hydatid disease of liver. Pathology Seeding involves the entire peritoneum and gives appearance of an multiloculated mass.  Classification Peritoneal hydatidosis can be pri...
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Peritoneal ligaments

The peritoneal ligaments are double layers of peritoneum that pass from one organ to another or from an organ to one of the abdominal walls. Suspensory ligaments of the liver right triangular ligament left triangular ligament falciform ligament Peritoneal ligaments of the stomach lesser om...
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Peritoneal mesothelioma

Peritoneal mesothelioma is an uncommon primary tumour of the peritoneal lining. It shares epidemiological and pathological features with but is less common than its pleural counterpart, which is described in detail in the general article on mesothelioma. Other subtypes (also discussed separately...
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Peritoneal metastases

Peritoneal metastases are a relatively common location for metastases, particularly from tumours of the abdomen and pelvis, that generally imply a poor prognosis, often with a significant impact on palliation 1. Terminology If peritoneal metastases are of an epithelial origin (as most are) and...
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Peritoneal spaces

Peritoneal spaces are separate compartments within the peritoneal cavity. These spaces are separated or compartmentalized by various peritoneal ligaments and their attachments.  The peritoneal spaces are important in the peritoneal diseases, ascites, intraperitoneal collections or peritoneal me...
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Peritoneum

The peritoneum is a large complex serous membrane which forms a closed sac within the abdominal cavity. In the female, this closed sac is perforated by the lateral ends of the fallopian tubes. It is a potential space between the parietal peritoneum lining the abdominal wall and the visceral peri...
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Perivascular epithelioid cell tumours (PEComas)

Perivascular epithelioid cells tumours (PEComas) are a group of related mesenchymal tumours and tumour-like conditions found in many locations. This group includes: angiomyolipoma (AML) clear cell 'sugar' tumour of the lung lymphangioleiomyomatosis (LAM) clear cell myomelanocytic tumour (CCM...
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Per-oral oesophageal myotomy (POEM)

Per-oral oesophageal myotomy (POEM) is a natural orifice endoscopic surgery that has been gaining increasing use as an alternative to traditional oesophageal myotomies (e.g. Heller myotomy and Nissen fundoplication). With this technique, the endoscopist insufflates the oesophagus with CO2 then ...
Article

Peroral pneumocolon

Peroral pneumocolon is a technique that can be used during a small bowel follow through (SBFT) to better visualize the ascending colon and terminal ileum. Procedure The goal of a peroral pneumocolon is to create a double contrast study (oral contrast and gas) of the ascending colon and termina...
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PET-CT indications

PET-CT is a combination of cross-sectional anatomic information provided by CT and the metabolic information provided by positron emission tomography (PET). PET is most commonly performed with 2-[F-18]fluoro-2-deoxy-D-glucose (FDG). Fluorine-18 (F-18) is an unstable radioisotope and has a half-...
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Petersen hernia

Petersen hernias are internal hernias which occur in the potential space posterior to a gastrojejunostomy. This hernia is caused by the herniation of intestinal loops through the defect between the small bowel limbs, the transverse mesocolon and the retroperitoneum, after any type of gastrojejun...
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Peutz-Jeghers syndrome

Peutz-Jeghers syndrome is one of the polyposis syndromes. It has an autosomal dominant inheritance and is characterised by: multiple hamartomatous polyps, most commonly involving the small intestine (predominantly the ileum), but also colon and stomach; mouth and oesophagus are spared mucocuta...
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Phlegmonous enteritis

Phlegmonous enteritis is a rare, life threatening disorder characterized by bacterial infection of the submucosal and muscularis layers of the gastrointestinal tract. The stomach is the most commonly involved site, with more than 100 cases reported in the literature. The mortality rate due to ph...
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Phlegmonous gastritis

Phlegmonous gastritis (also known as phlegmonitis of the stomach) is an uncommon, life-threatening condition which is due to diffuse infection of the submucosa of the stomach.  Epidemiology Although the gastric form is the commonest type of phlegmonitis seen in the GI tract, it remains rare, w...
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Phrenic ampulla

The phrenic ampulla (also known as the oesophageal vestibule) is the region between the A-ring and B-ring of the distal oesophagus.  The gastro-oesophageal junction is below the ampulla (and gastric folds should not enter the region of the ampulla). Differential diagnosis The ampulla is more ...
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Plummer-Vinson syndrome

Plummer-Vinson syndrome, also known as the Paterson-Brown-Kelly syndrome, predisposes to hypopharyngeal squamous cell carcinoma and consists of four features: dysphagia iron-deficiency anaemia weight loss oesophageal webs or hypopharyngeal webs The condition is more common in women.
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Pneumatosis coli

Pneumatosis coli is a descriptive sign presenting radiographically as intramural gas limited to the colonic wall.  Terminology There are different terminologies in the medical literature, such as pneumatosis intestinalis, pneumatosis coli, and pneumatosis cystoides intestinalis. Pneumatosis in...
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Pneumatosis intestinalis (mnemonic)

A helpful mnemonic for remembering the causes of pneumatosis intestinalis is: ChIPS Mnemonic C: chronic obstructive pulmonary disease I:  ischaemia P: pneumatosis cystoides intestinalis S: scleroderma/steroids
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Pneumoperitoneum

Pneumoperitoneum describes gas within the peritoneal cavity, often due to critical illness. There are numerous causes and several mimics. Pathology The most common cause of pneumoperitoneum is from the disruption of the wall of a hollow viscus. In children, the causes are different from the ad...
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Pneumoperitoneum (summary)

This is a basic article for medical students and other non-radiologists Pneumoperitoneum describes gas within the peritoneal cavity and is often the harbinger of a critical illness, often perforation of a hollow viscus. Pneumoperitoneum is distinct from pneumoretroperitoneum (much rarer) and ma...
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Pneumoretroperitoneum

Pneumoretroperitoneum is by definition presence of gas within the retroperitoneal space. Pathology Pneumoretroperitoneum is always abnormal and has a relatively small differential: perforated retroperitoneal hollow viscus duodenum peptic ulcer disease blunt or penetrating abdominal trauma ...
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Point-of-care ultrasound (curriculum)

The point-of-care ultrasound (PoCUS) curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core applications of ultrasonography in a point-of-care setting. Point-of-care ultrasound refers to ultrasonography which may be simultaneously performed,...
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Polo Mint sign (venous thrombosis)

The Polo Mint sign is a description given to a venous thrombosis on contrast-enhanced CT imaging.  When viewed in the axial plane, a thin rim of contrast persists around a central filling defect due to thrombus. This gives an appearance like that of the popular UK mint sweet, the Polo, also refe...
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Polyarteritis nodosa

Polyarteritis nodosa (PAN) is a systemic inflammatory necrotising vasculitis that involves small to medium-sized arteries (larger than arterioles).  Epidemiology PAN is more common in males and typically presents around the 5th to 7th decades. 20-30% of patients are hepatitis B antigen positiv...
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Polyglandular autoimmune syndromes

Polyglandular autoimmune syndromes (PAS) are a rare set of diseases characterised by the presence of ≥2 autoimmune endocrine disease. Pathology Three types of PAS have been described.  PAS type I a.k.a. APECED (autoimmune polyendocrinopathy, candidiasis and ectodermal dystrophy) or MEDAC (mu...
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Polyposis syndromes

The polyposis syndromes are disorders in which more than 100 gastrointestinal polyps are present throughout the GI tract: hereditary hereditary nonpolyposis colorectal cancer familial adenomatous polyposis syndrome (FAPS) classic FAP Gardner syndrome  Turcot syndrome Bannayan–Riley–Ruvalc...
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Polysplenia syndrome

Polysplenia syndrome, also known as left isomerism, is a type of heterotaxy syndrome where there are multiple spleens congenitally as part of left-sided isomerism. Epidemiology Polysplenia is seen predominantly in female patients. It is usually diagnosed in childhood or adulthood, later than a...
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Portal hypertensive gastropathy / enteropathy / colopathy

In portal hypertension, chronic portal venous congestion leads to dilatation and ectasia of the submucosal vessels in the stomach (portal hypertensive gastropathy), small bowel (portal hypertensive enteropathy) and/or large bowel (portal hypertensive colopathy). This may result in upper or lower...
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Portal vein calcification

Portal vein calcification is a rare radiologic finding which can be seen in long-standing portal venous hypertension. Pathology Calcium may be deposited in a thrombus or in the wall of the portal vein and is more rarely found in the splenic vein and superior mesenteric vein. One of the propos...
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Portal venous gas

Portal venous gas is the accumulation of gas in the portal vein and its branches. It needs to be distinguished from pneumobilia, although this is usually not too problematic, when associated findings are taken into account along with the pattern of gas (i.e. peripheral in portal venous gas, cent...
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Portal venous system

The portal venous system refers to the vessels involved in the drainage of the capillary beds of the GI tract and spleen into the capillary bed of the liver. Blood flow to the liver is unique in that it receives both oxygenated and deoxygenated blood. As a result, the partial pressure of oxygen...
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Portosystemic collateral pathways

Portosystemic collateral pathways (also called varices) develop spontaneously via dilatation of pre-existing anastomoses between the portal and systemic venous systems. This facilitates shunting of blood away from the liver into the systemic venous system in portal hypertension, as a means for r...
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Portosystemic shunt ratio

The portosystemic shunt ratio is a measure performed using ultrasound to quantify the abnormal flow of portal venous blood that is shunted away from the hepatic sinusoidal circulation in the context of a congenital portosystemic shunt 1. Ultrasound The ratio is determined using the following e...
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Posterior pararenal space

The posterior pararenal space is the smallest and most clinically insignificant portion of the retroperitoneum. Gross anatomy It is filled with fat, blood vessels and lymphatics, but contains no major organs. Boundaries posteriorly: bound by transversalis fascia anteriorly: bound by posteri...
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Postoperative free intraperitoneal gas

Postoperative free intraperitoneal gas refers to the presence of gas in the peritoneal cavity following a surgical procedure and may result from open or laparoscopic surgical techniques.   Terminology Postoperative free intraperitoneal gas is also referred to as postoperative pneumoperitoneum...
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Posttransplant lymphoproliferative disorder

Post-transplant lymphoproliferative disorder (PTLD), also referred as post-transplant lymphoproliferation disorder, represents a variety of conditions ranging from lymphoid hyperplasia to malignancy, included in the 2008 WHO classification of tumours of haematopoietic and lymphoid tissues. It ca...
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PPP syndrome

PPP syndrome is the extremely rare association of pancreatitis, panniculitis, and polyarthritis. Epidemiology Most commonly affects middle-aged male patients with a history of heavy alcohol use 1,2.  Clinical presentation In the majority of cases, abdominal symptoms are mild or absent, makin...
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Pre-aortic lymph nodes

Pre-aortic nodes are part of the abdominopelvic lymph nodes. They include 3 main groups:  coeliac nodes drainage from gastric nodes, hepatic nodes and pancreaticosplenic nodes superior mesenteric nodes drainage from mesenteric nodes inferior mesenteric nodes drainage from mesenteric nodes
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Presacral space

The presacral space is located between the rectum and the sacrococcygeal part of the spine. Gross anatomy Contents The presacral space contains a variety of tissue: fat mesenchymal tissue lymph nodes nerve plexuses blood vessels Boundaries superior - peritoneal reflections inferior - ...
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Presbyoesophagus

Presbyoesophagus is term that has been traditionally used to describe the manifestations of degenerating motor function in the aging oesophagus. Presbyoesophagus remains controversial given it was initially described in elderly patients with significant co-morbidities (e.g. dementia, diabetes),...
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Primary cutaneous melanoma

Primary cutaneous melanoma is the most common subtype of malignant melanoma, a malignant neoplasm that arises from melanocytes. Melanocytes predominantly occur in the basal layer of the epidermis but do occur elsewhere in the body. Primary cutaneous melanoma is by far the most common type of pri...
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Primary peritoneal neoplasms

Primary peritoneal neoplasms comprise an uncommon group of heterogenous entities. The list includes: mesothelial derivatives primary (malignant) peritoneal mesothelioma primary peritoneal multicystic mesothelioma primary peritoneal well-differentiated papillary mesothelioma primary periton...
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Primary pneumatosis intestinalis

Primary pneumatosis intestinalis (PPI) is a benign idiopathic condition in which multiple gas-filled cystic lesions are seen in the gastrointestinal tract wall. The changes are usually seen initially on radiography or CT with CT being the more sensitive test. Epidemiology Primary pneumatosis i...
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Primary retroperitoneal neoplasms

Primary retroperitoneal neoplasms are an extremely rare group of tumours (lymphoma is not included in this definition). The most common type is soft tissue sarcoma (90%). Epidemiology The most common age for presentation is 40-50 years.  Clinical presentation Frequently tumours have relative...
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Primary serous papillary carcinoma of the peritoneum

A primary serous papillary carcinoma of the peritoneum (PSPCP) is an extremely rare primary peritoneal tumour. Epidemiology They usually present in postmenopausal women. Clinical presentation Patients tend to present with non-specific complaints such as abdominal pain, anorexia, and abdomina...
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Proctalgia fugax

Proctaglia fugax is a disorder characterised by rectal pain that is considered to be functional in aetiology, and thus is a diagnosis of exclusion. Clinical presentation The classic presentation, which form the Rome IV diagnostic criteria if all present for three months, include 1,2: recurren...
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Properitoneal fat

The properitoneal fat, deep to the transversalis fascia, fills the posterior pararenal space. Laterally it thickens and forms the properitoneal fat pad, which is an anterior extension of posterior pararenal space. Terminology The properitoneal fat pad is known as a plane in surgical anatomy, a...
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Pseudoachalasia

Pseudoachalasia is achalasia-pattern dilatation of the oesophagus due to the narrowing of the distal oesophagus from causes other than primary denervation. One of the most common causes is malignancy (often submucosal gastric cancer) with extension in the lower oesophagus. The clinical and imagi...
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Pseudokidney (intussusception)

The pseudokidney of intussusception is an ultrasound finding in some cases of intestinal intussusception. It refers to the longitudinal ultrasound appearance of the intussuscepted segment of bowel which mimics a kidney.  The fat-containing mesentery which is dragged into the intussusception, co...
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Pseudomyxoma peritonei

Pseudomyxoma peritonei refers to the intraperitoneal accumulation of a gelatinous ascites secondary to rupture of a mucinous tumour. The most common cause is a ruptured mucinous tumour of the appendix/appendiceal mucocoele 10.   Occasionally, mucinous tumours of the colon, rectum, stomach, panc...
Article

Pseudopancreatitis

Pseudopancreatitis refers to the presence of fluid in or around the pancreas in the setting of trauma but in the absence of direct signs of traumatic pancreatic injury. Most patients will have a normal serum lipase level, but amylase has a limited sensitivity and specificity for pancreatic traum...
Article

Pseudopneumoperitoneum

Pseudopneumoperitoneum describes any gas within the abdominal cavity that masquerades as free intraperitoneal gas or pneumoperitoneum when it is in fact contained within an organ. Correctly identifying pneumoperitoneum is important, but making the diagnosis in error may lead to further unnecessa...
Article

Pseudopneumoretroperitoneum

Pseudopneumoretroperitoneum is the radiographic finding of gas within the abdominal region that mimics the appearance of pneumoretroperitoneum (cf. the analogous pseudopneumoperitoneum i.e. abdominal gas that erroneously suggests pneumoperitoneum).  Causes of pseudopneumoretroperitoneum include...
Article

Pseudovein sign (bowel)

The pseudovein sign can occur with active gastrointestinal bleeding where contrast extravasation during angiography may have a curvilinear appearance as it pools in the gastric rugae or mucosal folds of bowel, mimicking the appearance of a vein. However, contrast in the “pseudovein” persists bey...
Article

Pyloric stenosis

Hypertrophic pyloric stenosis (HPS) refers to the idiopathic thickening of gastric py­loric musculature which then results in progressive gastric outlet obstruction. Epidemiology Pyloric stenosis is relatively common, with an incidence of approximately 2-5 per 1,000 births, and has a male pred...
Article

Radiation enteritis

Radiation enteritis is a bowel pathology resulting from toxic effects of radiotherapy on the bowel wall and vasculature.  Epidemiology 5-15% of patients treated with radiotherapy (usually > 4500cGy) develop chronic radiation enteropathy. Clinical presentation The clinical presentation is non...
Article

Radiological signs (gastrointestinal tract)

Radiological signs are described across the disciplines of imaging, including the gastrointestinal tract. Fruit-inspired, nature-related, and more feature in the list of signs described for a wide array of pathology. How fascinating are the minds of radiologists work in describing pathology?
Article

Ranson criteria

Ranson's criteria are useful in assessing prognosis in early acute pancreatitis. The more of the criteria are met the higher the mortality. Ranson's criteria are assessed both at admission and at 48 hours. Criteria On admission age: >55 years white blood count: >16 000/mm blood glucose leve...
Article

Rapunzel syndrome

Rapunzel syndrome is the term for a trichobezoar (gastric 'hair ball') which has a tail-like extension into the small bowel through the pylorus causing gastric outlet obstruction. For discussion of other gastrointestinal foreign bodies, please see: bezoars. Clinical presentation The patient u...
Article

RASopathy

RASopathies are a class of developmental disorders caused by germline mutations in genes that encode for components or regulators of the Ras/mitogen activated protein kinase (MAPK) pathway. Epidemiology As a group, RASopathies represent one of the most common malformation syndromes, with an in...
Article

Rat-tail sign (oesophagus)

The rat-tail sign is used to refer to the tapering of the inferior oesophagus in achalasia. The same appearance (although it is difficult to see the similarity) is also referred to as the ​bird beak sign (oesophagus). 
Article

Recreational drug use (radiological manifestations)

Radiological manifestations of recreational drug use are not infrequently seen as the use of recreational drugs is widespread. Epidemiology Interestingly, recent reports have suggested a decreasing incidence of reported drug use in the general population over the past decade, but it remains th...
Article

Rectal cancer

Rectal cancer, although sharing many of the features of generic colorectal carcinoma (CRC), has some features that make it unique. These are predominantly related to its anatomical location which has implications in both preoperative imaging assessment and surgical technique. Demographics and c...
Article

Rectal cancer protocol (MRI)

Pelvic MRI protocol for rectal cancer includes: through tumour (always ensure planes are exactly perpendicular to the wall) three-plane T2 axial T1 narrow field of view images to be included overviews axial T2FS axial T1 See also MRI protocols
Article

Rectal cancer (staging)

Staging strongly influences the success of and rate of local recurrence following rectal cancer resection. MRI is the modality of choice for the staging of rectal cancer, to guide surgical and non-surgical management options. MRI is used at diagnosis, following downstaging chemoradiotherapy, and...
Article

Rectal foreign bodies

Rectal foreign bodies are not uncommon in emergency departments around the world, and although they are often the source of endless amusement do potentially cause management difficulties. Epidemiology The incidence varies according to the region, said to be uncommon in Asia and most common in ...

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