The right subphrenic space (a.k.a. right anterior space, right subdiaphragmatic space) is a potential space that lies between the right lobe of the liver and the inferior surface of the diaphragm.
This is a subcompartment of the supracolic compartment. It reaches as far as the up...
The right supramesocolic space is an arbitrary subdivision of the supramesocolic space, which lies between the diaphragm and the transverse colon.
The right supramesocolic space is separated from the left supramesocolic space by the falciform ligament, and can be divided into thr...
The Rigler sign, also known as the double wall sign, is seen on a radiograph of the abdomen when the air is present on both sides of the intestine, i.e. when there is air on both the luminal and peritoneal side of the bowel wall.
Pneumoperitoneum may be a result of perforation or, recent instru...
Ring shadows are radiographic signs seen on either chest x-rays or on upper gastrointestinal fluoroscopy:
ring shadow (chest)
ring shadow (abdomen)
Rokitansky-Aschoff sinuses are diverticula of the gallbladder wall which may be microscopic or macroscopic. Histologically, they are outpouchings of gallbladder mucosa that sit within the gallbladder muscle layer.
They are not of themselves considered abnormal, but may be ass...
Rose-thorn ulcers or rose-thorn appearance refers to deep penetrating linear ulcers or fissuring typically seen within stenosed terminal ileum with a thickened wall. They appear as thorn-like extraluminal projections on barium studies and this appearance is one of the typical signs of Crohn dise...
In many centers, laparoscopic Roux-en-Y gastric bypass has become the most common bariatric procedure for morbid obesity.
In this operation, the stomach is stapled or divided to form a small pouch (typically <30 mL in volume), which empties into a Roux limb of the jejunum of varying length (ty...
A Roux limb may be formed in multiple different gastrointestinal surgeries, including
bariatric surgery, e.g.
Roux-en-Y gastric bypass
partial pancreaticoduodenectomy (Whipple procedure)
In these surgeries the small bowel is ...
The rugal folds are the mucosal folds within the stomach that give the distinctive appearance on barium studies.
The rule of 2s is a useful mnemonic for Meckel diverticulum.
occur in 2% of the population
are 2 inches (5cm) long
are 2 feet (60cm) from the ileocaecal valve
2/3rds have ectopic mucosa
2 types of ectopic tissue are commonly present (mostly gastric and pancreatic)
Ruptured omphalocoele occurs when there is rupture of the outer membrane of an omphalocoele. When this happens the eviscerated fetal bowel looks free floating and distinction from gastroschisis becomes difficult. However the abdominal defect generally tends to be larger and may contain liver wit...
The saber sign refers to a pattern of gas distribution seen in supine abdominal radiographs of patients with pneumobilia. A sword-shaped lucency is apparent in the right paraspinal region of the upper abdomen representing arching gas extending from the common bile duct into the left hepatic duc...
A sandwich sign, sometimes known as a hamburger sign, refers to a mesenteric nodal mass, either para-aortic or not, giving an appearance of a hamburger. Confluent lymphadenopathy on both sides of the mesenteric vessels gives rise to an appearance described as the sandwich sign 2.
The sign is sp...
A Schatzki ring, also called Schatzki-Gary ring, is symptomatically narrow oesophageal B-ring occurring in the distal oesophagus and usually associated with a hiatus hernia.
Relatively common, lower oesophageal rings are found in ~10% of oesophagrams.
Scirrhous carcinoma of the gastrointestinal tract is a subtype of primary adenocarcinoma of the gastrointestinal (GI) tract.
It is the least common type of primary adenocarcinoma involving mainly the stomach and the colon.
The tumour demonstrates an infiltrative behavi...
Scleroderma, also known as systemic sclerosis, is an autoimmune connective tissue disorder characterised by multisystem fibrosis and soft tissue calcification. As such, it affects many separate organ systems, which are discussed separately:
musculoskeletal manifestations of scleroderma
Gastrointestinal manifestations of scleroderma can occur in up to 90% of patients with scleroderma 2 with the commonest site of GI involvement being the oesophagus.
As clinical presentation, radiographic appearances and differential diagnosis vary with the location of involvement these are disc...
Sclerosing encapsulating peritonitis is a rare benign cause of acute or subacute small bowel obstruction. It is characterised by total or partial encasement of the small bowel within a thick fibrocollagenous membrane.
The condition was originally termed abdominal cocoon. It has als...
Sclerosing mesenteritis (or mesenteric panniculitis) is an uncommon idiopathic disorder characterised by chronic non-specific inflammation involving the adipose tissue of the bowel mesentery.
Typically this condition afflicts adults in their sixties with mild male predilection, ...
The seatbelt sign is both a clinical and radiological sign. It is simply the presence of bruising/abrasions in the distribution of a seatbelt (i.e. horizontal and/or diagonal) across the abdomen, chest and sometimes neck.
A positive seatbelt sign, in combination with abdominal pain or tenderne...
The seatbelt syndrome is the constellation of traumatic injuries associated with three-point seatbelts:
lumbar spine fracture
Segmental arterial mediolysis (SAM) is an increasingly recognised vascular disease of the middle-aged and elderly and a leading cause of spontanoeus intra-abdominal haemorrhage. It is characterised by fusiform aneurysms, stenoses, dissections and occlusions within splanchnic arterial branches. I...
Segmental pancreatitis is not a distinct entity in itself but describes an imaging differential.
With segmental pancreatitis, a patient presents with clinical pancreatitis (signs, symptoms, laboratory markers), but on imaging, only a portion of the gland appears to have c...
SeHCAT (23-seleno-25-homo-tauro-cholic acid) is a radiopharmaceutical used in the investigation of bile salt malabsorption, which is a cause of chronic diarrhoea.
physical half-life: 118 days
Uses, dosage and timings
A capsule containing SeHCAT is ingested with water. The pa...
The semilunar line, linea semilunaris or Spigelian line is a bilateral vertical curved line in the anterior abdominal wall where the layers of the rectus sheath fuse lateral to the rectus abdominis muscle and medial to the oblique muscles.
It is the site of a Spigelian hernia.
A sentinel loop is a short segment of adynamic ileus close to an intra-abdominal inflammatory process.
The sentinel loop sign may aid in localising the source of inflammation. For example, a sentinel loop in the upper abdomen may indicate pancreatitis, while one in the right lower quadrant may ...
Serous cystadenoma of the pancreas (or microcystic adenoma) is an uncommon type of benign cystic pancreatic neoplasm.
There is a recognised strong female predilection (M:F ~ 1:4) and usually presents in middle age to elderly patients (>60 years of age).
Serrated polyposis syndrome (SPS), also called hyperplastic polyposis syndrome, is characterised by the presence of multiple serrated polyps or a mixture of serrated and hyperplastic polyps, with the exact number required for diagnosis dependent on location and family history.
SPS has an hetero...
Seurat spleen is an angiographic appearance seen following blunt trauma to the spleen. Multiple small punctate regions of intraparenchymal contrast extravasation lead to a spotted appearance.
History and etymology
The term refers to a likeness between the angiographic appearance and the artwor...
Shading sign is an MRI finding typically seen in an endometrioma. It may also be seen with some endometrioid tumours (e.g endometrioid carcinoma of the ovary)
It helps to distinguish endometriomas from other blood-containing lesions (e.g. haemorrhagic corpus luteum cysts), with a sensitivity of...
Shock bowel is the appearance of the bowel in a state of hypotension. It is usually seen as part of the CT hypoperfusion complex.
thickened bowel loops (>3 mm) with enhancing walls (the reason the condition was previously known as "shock bowel")
on non-contrasted im...
The short gastric arteries are a group of short arteries arising from the terminal splenic artery and the left gastroepiploic artery which supply the fundus of the stomach along it's greater curvature.
The vessels are short in length, variable in number and course through the gastrosplenic liga...
The Shwachman-Diamond syndrome (SDS) or Shwachman-Bodian-Diamond syndrome (SBDS) is a rare autosomal recessive disorder characterised by 1 :
exocrine pancreatic insufficiency
bone marrow hypoplasia (cyclic neutropenia)
Patients with Shwachman-...
The sigmoid arteries are branches, between two-to-four, of the inferior mesenteric artery (IMA) and supply the sigmoid colon.
origin: inferior mesenteric artery
course: after arising from IMA, these branches descend to the left in the sigmoid mesocolon
superiorly with ...
The sigmoid colon is the continuation of the descending colon.
After the distal descending colon has curved medially it enters the pelvis, where it gains a mesentery and is then called the sigmoid colon. It measures approximately 15 cm in length.
It has a "S" (Greek letter sigm...
The sigmoid mesocolon
is a fold of peritoneum that attaches the sigmoid colon to the pelvic
wall and one of the four mesenteries in the abdominal cavity.
It has an "inverted V" line of attachment, the apex of which is
near the division of the left common iliac artery.
The left limb descends...
Intersigmoid hernias, also known as sigmoid mesocolon hernias, occur when small bowel loops protrude into a peritoneal pocket (intersigmoid fossa) formed between two adjacent sigmoid segments and their mesentery.
Sigmoid mesocolon hernias account for ~5% of all internal hernias 1,...
Sigmoid volvulus is a cause of large bowel obstruction and occurs when the sigmoid colon twists on its mesentery, the sigmoid mesocolon.
Large bowel volvulus accounts for ~5% of all large bowel obstructions, with ~60% of intestinal volvulus involving the sigmoid colon 6. It is mor...
The following points may be helpful to distinguish between sigmoid volvulus and caecal volvulus on plain film.
arises in the pelvis (left lower quadrant)
extends towards the right upper quadrant
ahaustral in appearance
sigmoid volvulus causes obstruction of the proximal lar...
Simple pancreatic cysts, also known as true epithelial cysts or retention cysts, are unilocular cysts within the pancreas, lined by a monolayer of epithelium, which lack communication with the pancreatic ducts 1,5. In contradistinction to other solid viscera, simple cysts in the pancreas are a r...
Single contrast barium enema is a method of imaging the colon with fluoroscopy and is similar in concept to the double contrast barium enema. "Single contrast" refers to imaging with barium or water-soluble contrast only, without addition of air or CO2.
The single contrast techniqu...
A Sister Mary Joseph nodule is a metastatic lesion involving the umbilicus. The most common primary source is an intra-abdominal adenocarcinoma.
Umbilical metastases are uncommon, reportedly present in 1-3% of all intra-abdominal and/or pelvic malignancy 7.
The Sitz marker study is an older technique to estimate colonic transit time.
In constipation it can help distinguish between slow colonic transit and a defecation disorder.
The patient ingests a number of radio-opaque markers (plastic rings containing radio-opaque mat...
A mnemonic for the skin changes associated with mercury poisoning is:
Sleeve gastrectomy is a bariatric surgical procedure involving resection of the greater curvature of the fundus and body of the stomach to leave approximately 15% of the original gastric volume (60 to 100 cc), thus creating a restrictive physiology. The post-surgical gastric pouch resembles a ba...
The small bowel (or small intestine) is the section of bowel between the stomach and the colon. It has distinctive mucosal folds, valvulae conniventes, and is made up of three functional units:
See main article: barium studies of sma...
Small bowel atresia corresponds to malformations where there is a narrowing or absence of a portion of the small bowel, which includes:
The small bowel carcinoid tumours are the most common gastrointestinal carcinoid tumours. Within the small bowel, the most common site is at the terminal ileum.
Small bowel carcinoid tumours account for ~40% of gastrointestinal carcinoid tumours 1.
The small bowel faeces sign can be observed on abdominal CT scans. The sign has been described as a finding specific for small bowel obstruction or another severe small bowel abnormality (e.g. metabolic or infectious disease). While the reported prevalence of the sign in small bowel obstruction ...
Regular, smooth generalised thickening
congestive cardiac failure (CCF)
anticoagulation or bleeding diathesis
IgA vasculitis (Henoch-Schonlein purpura)
Small bowel follow through (SBFT) is a fluoroscopic technique designed to obtain high resolution images of the small bowel. The function of the small bowel can also be evaluated.
The small bowel follow through can be used for evaluation of small bowel abnormalities, including:
Small bowel imaging aims at assessment of the disorders of small intestine.
barium follow through
Small bowel or mesenteric ischaemia may be a life-threatening condition, arising from any one of numerous causes of disturbance of the normal blood flow through the small bowel wall.
It can be divided into acute and chronic forms, with the main underlying aetiologies (each discussed...
Small bowel lymphoma is the most common small bowel malignancy, accounting accounts for ~25% of all primary small bowel malignancies and ~40% of all primary gastrointestinal lymphomas.
Small bowel lymphoma is most commonly secondary extranodal involvement in widespread systemic ly...
Small bowel mesentery internal hernias are a form internal bowel herniation, involving protrusions of viscera through defects in the peritoneum or bowel mesentery. This type of internal herniation is more often seen in neonates than in adults.
There are two types:
transmesenteric small bowel i...
Small bowel obstruction (SBO) accounts for 80% of all mechanical intestinal obstruction, the remaining 20% results from large bowel obstruction. It has a mortality rate of ~5%.
Classical presentation is cramping abdominal pain and abdominal distension with nausea and vomi...
This is a basic article for medical students and other non-radiologists
Small bowel obstruction (SBO) accounts for 80% of all mechanical intestinal obstruction; the remaining 20% result from large bowel obstruction. It has a mortality rate of 5.5%.
This is a summary article;...
Soft-tissue sarcomas are a heterogeneous group of malignant tumours of mesenchymal origin (sarcoma) that originate from the soft tissues rather than bone. They are classified on the basis of tissue seen on histology. The commoner sarcomas in the adult and paediatric population are listed below.
The solid abdominal viscera (singular: viscus) is a collective term for those internal organs of the upper abdomen that are primarily solid in nature, namely the liver, pancreas, spleen, adrenals, and kidneys. It is used in contradistinction to the hollow abdominal viscera, which includes, the s...
This article is currently under editorial board review for errors
Solitary rectal ulcer syndrome (SRUS) is a chronic, benign disorder characterised by the presence of a benign abnormality of the rectum in persons who have a long history of straining during defecation. it is a misnomer but has g...
Somatostatinomas are a rare type of neuroendocrine tumour. They may represent around 1% of all gastro-entero-pancreatic endocrine neoplasms.
Presentation van be variable. Patients with functional stomatostatinomas may present with an "inhibitory syndrome" which is a triad...
Lymphadenopathy is quite common, and it can be very difficult to differentiate malignant lymphadenopathy from reactive nodal enlargement.
Several gray scale and colour Doppler features favour malignancy in a lymph node.
Gray scale parameters that favour malignancy
size: larger-more likely mal...
The sphincter of Oddi (or sphincter of ampulla) is a complex of four smooth muscle sphincters within the duodenal wall. It surrounds, and helps fix to the duodenum, the duct of Wirsung, common bile duct and the ampulla of Vater 1-2.
When relaxed it allows the passage of bile into the intestine...
Spigelian-cryptorchidism syndrome is the association of Spigelian hernias and cryptorchidism in children.
It is reported that ~50% (range 28-75%) range of paediatric patients with Spigelian hernias will have ipsilateral cryptorchidism 1,2.
Along with Spigelian hernia and cryptorch...
Spigelian hernia, also known as lateral ventral hernia, is a type of abdominal hernia along the semilunar line, resulting in herniation between the muscles of the abdominal wall.
They are rare and account for ~1% (range 0.1-2%) of ventral hernias 2,3. The incidence is thought to p...
The spleen is an organ of the haematological system and has a role in immune response, storage of red blood cells and haematopoiesis.
The spleen is a wedge-shaped organ lying mainly in the left upper quadrant (left hypochondrium and partly in the epigastrium) and is protected by ...
The spleen size varies with a child's age.
The three numbers below represent the 10th percentile, median, and 90th percentile for the long axis of the spleen (cm)
0-3 months: (3.3, 4.5, 5.8 cm)
3-6 months: (4.9, 5.3, 6.4 cm)
6-12 months: (5.2, 6.2, 6.8 cm)
1-2 years: (5.4, 6.9, 7.5 cm)
Splenic amyloidosis is rare as an isolated entity. Most often it is associated with either systemic amyloidosis or hepatic amyloidosis.
In general splenic involvement in amyloidosis is rather frequent (5-10% of cases 6).
Symptoms include abdominal mass and ...
The splenic artery is one of three branches coeliac trunk and supplies the spleen as well as large parts of the stomach and pancreas.
Origin and course
The splenic artery is one of the terminal branches of the coeliac trunk, passing from the coeliac axis toward the splenic hilum...
Splenic artery pseudoaneurysms are a rare type of pseudoaneurysm arising from any portion of the splenic artery and its branches.
Unlike splenic artery true aneurysms, splenic artery pseudoaneurysms will nearly always present with symptoms 2. Fewer than 200 cases of sple...
Brucellosis is a common zoonosis, which is particularly prevalent in Mediterranean countries. It produces a multisystemic illness that can present with a broad spectrum of clinical manifestations and complications 1.
This article is focusing on the splenic involvement by brucellosis. For genera...
Splenic calcifications can occur is various shapes and forms and can occur from a myriad of aetiological factors.
The usual calcification observed in radiographs are the multiple, miliary form presenting numerous small rounded densities averaging from three to five millimeters in diameter where...
Splenic epithelial cysts, also referred as splenic epidermoid cysts or primary splenic cysts, are unilocular fluid lesions with thin and smooth walls and no enhancement. They represent ~20% of cysts found in the spleen, and are usually an innocuous incidental imaging finding.
Note that most (~8...
Splenic haemangiomas, also known as splenic venous malformations, splenic cavernous malformations, or splenic slow flow venous malformations, while being rare lesions, are considered the second commonest focal lesion involving the spleen after simple splenic cysts 5,12 and the most common primar...
Splenic haemangiomatosis involves multiple, diffuse splenic haemangiomas replacing its entire parenchyma. It is a very rare entity.
It can occur as a manifestation of systemic angiomatosis or, less commonly, confined to the spleen (diffuse isolated splenic haemangiomatosis). There is...
Splenic infarction is a result of ischaemia to the spleen, and in many cases requires no treatment. However, identification of the cause of infarction is essential.
Splenic infarcts can occur due to a number of processes, involving either arterial supply, the spleen itself or th...
There are a number of splenic lesions and anomalies:
Benign mass lesions
splenic cyst (mnemonic)
splenic haemangioma: commonest benign sp...
Splenic lymphangiomas are relatively rare benign tumours that correspond to abnormal dilatation of lymphatic channels that can be either congenital or acquired.
On imaging, they usually present as lobulated and multiloculated cystic lesions without solid component or significant enhancement.
Splenic siderotic nodules, also known as Gamna-Gandy bodies, of the spleen, are most commonly encountered in portal hypertension. The pathophysiological process is the result of microhaemorrhage resulting in haemosiderin and calcium deposition followed by fibroblastic reaction.
Splenic trauma can occur after blunt or penetrating trauma or secondary to medical intervention (i.e. iatrogenic). The spleen is the most frequently injured internal organ after blunt trauma.
In blunt trauma, the spleen can account for up to 49% of abdominal organ injuries 2.
The splenic vein drains the spleen, part of the pancreas, and part of the stomach.
Origin and course
The splenic vein is formed by splenic tributaries emerging at the splenic hilum in the splenorenal ligament at the tip of the tail of pancreas. It runs in the splenorenal ligame...
Splenomegaly is a term which refers to enlargement of the spleen. The normal adult splenic length upper limit is usually around 12-15 cm. Also one should know how to calculate splenic index, volume and mass by CT and MR techniques. Massive splenomegaly is a term used when the spleen weighs >1000...
Splenorenal ligament is a peritoneal ligament. It represents the dorsal most part of dorsal mesentery.
It contains pancratic tail.
In settings of portal hypertension, collateral circulation may establish within the splenorenal ligament.
Splenosis is one type of ectopic splenic tissue (the other being accessory spleen). It is an acquired condition and is defined as autoimplantation one or more focal deposits of splenic tissue in various compartments of the body.
Abdominal splenosis is seen after abdominal trauma or surgery (e.g...
Spontaneous splenic rupture (SSR) (or atraumatic splenic rupture) is rare, especially when compared to traumatic splenic rupture.
The pathogenesis of atraumatic splenic rupture is not well understood. Splenomegaly is present in almost all patients (~95%), although rupture of normal ...
Sprue is the collective term for the malabsorptive gastrointestinal enteropathies although it may be used to refer directly to tropical sprue. It is composed of two entities:
non-tropical sprue / coeliac disease
In each, the radiologic features are not sensitive enough to confi...
Stab wounds are a form of penetrating trauma that may be self-inflicted or inflicted by another person either accidentally or intentionally. They may be caused from a variety of objects and may occur anywhere in the body.
Although commonly caused by a knife as well, slash injuries ...
Stack of coins sign refers to the appearance of small bowel folds that are smoothly and uniformly thickened 1. The margins between the folds are sharply delineated and the arrangement of clearly demarcated parallel folds is likened to a stack of coins or a picket fence. This sign is distinct fro...
Stepladder sign may refer to:
intracapsular breast implant rupture (ultrasound)
gas-fluid levels in obstructed small bowel (erect abdominal radiograph)
Stepladder sign represents the appearance of gas-fluid distended small bowel loops that appear to be stacked on top of each other, typically observed on erect abdominal radiographs in the setting of small bowel obstruction.
Stercoral colitis refers to a condition where the presence of impacted faeces in the colonic lumen is associated with inflammation and distention of the affected colon segment.
It is seen primarily in elderly patients (often bedbound as a consequence of dementia, stroke, or orthop...
Stercoral perforation is defined as a bowel perforation due to pressure necrosis from a faecal mass (faecaloma) 1. It is an uncommon, but life-threatening, complication of unresolved faecal impaction and can be a cause of acute abdomen secondary to faecal peritonitis.
It may repre...
The Stierlin sign refers to repeated emptying of the caecum, seen radiographically as barium remaining in the terminal part of the ileum and in the transverse colon. This occurs due to irritation of the caecum caused by M. tuberculosis. It is not specific for tuberculosis and can also be seen in...