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...
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 in...
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...
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; read more in our article on small bowel obstruction.
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 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 stomach, small bowel...
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...
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 hematopoiesis.
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 t...
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...
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 cysts, although not particularly common, are the most common focal lesion of the spleen. They may be congenital or secondary.
The incidence is ~0.75 per 100,000.
Usually asymptomatic and incidentally discovered at imaging. Left upper quadrant pain and t...
Splenic epidermoid cysts are a type of non-parasitic primary splenic cyst.
They are thought to account for 10-25% of benign non-parasitic cysts of the spleen 3. There may be an increased female predilection.
The clinical presentation can vary ranging from b...
Splenic haemangiomas (also known as splenic venous malformations) while being rare lesions, are considered the second commonest focal lesion involving the spleen after simple splenic cysts 5,12.
Most splenic venous malformations are so called cavernous malformations, which are found throughout ...
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 hamartomas are very rare and usually solitary although may be present as multiple nodules present in tuberous sclerosis or Wiskott-Aldrich syndrome.
The only recently described entity sclerosing angiomatoid nodular transformation (SANT) of the spleen, a non-neoplastic vascular entity de...
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 processes, involving either arterial supply, the spleen itself and the ...
There are a number of splenic lesions and anomalies:
Benign mass lesions
splenic cysts: see cystic lesions of the spleen
splenic haemangioma: commonest benig...
Splenic lymphangiomas are relatively rare benign tumours that correspond to malformations of the lymphatic system.
Most occur in children, were rarely reported in adults2.
Presentation ranges from asymptomatic incidental finding to a large multicentric, ...
Atraumatic or spontaneous 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 spleens (both in size an...
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 organ after blunt trauma.
Patients may present with left upper quadrant/left chest pain, left shoulder tip pain (re...
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...
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...
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 perforation is defined as a bowel perforation due to pressure necrosis from a faecal mass (faecaloma) 1. It is uncommon, but a life-threatening, complication of unresolved faecal impaction and can be a cause of acute abdomen secondary to faecal peritonitis.
It may repres...
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...
The stomach is a muscular organ that lies between the oesophagus and duodenum in the upper abdomen. It lies on the left side of the abdominal cavity caudal to the diaphragm.
The stomach (normal volume 45 mL) is divided into distinct regions:
cardia: the area that receives the oe...
Stomal ulcers may occur after surgery for peptic ulcer disease, and are more common in settings of a retained gastric antrum or an incomplete vagotomy (occurrences which are not common with modern surgical technique). There is also a higher risk with Zollinger-Ellison syndrome.
Streak ovaries are a form of ovarian dysgenesis and are associated with Turner syndrome. Occasionally they may be functional and secondary sexual characteristics may develop.
Streak ovaries are seen when there is abnormality or absence of the X chromosome.
The string of beads sign is the description typically given to the appearance of the renal artery in fibromuscular dysplasia (FMD) but may also be used to describe the appearance of splanchnic arteries in segmental arterial mediolysis (SAM). It refers to the appearance arising from the stenoses ...
String of pearls sign can refer to:
string of pearls sign on an abdominal radiograph of fluid-filled dilated small bowel loops
string of pearls sign on ultrasound in polycystic ovarian syndrome
string of pearls sign for angiographic appearances in fibromuscular dysplasia
The string of pearls (or beads) sign can be seen on upright or decubitus abdominal radiographs as well as on CT in patients with small bowel obstruction, increased intraluminal fluid, and slow resorption of intraluminal gas.
It consists of an obliquely or horizontally oriented row of small gas ...
The gastrointestinal string sign (also known as the string sign of Kantor) refers to the string-like appearance of a contrast-filled bowel loop caused its severe narrowing.
Originally used to describe the reversible narrowing caused by spasms in Crohn disease, it is now used for any severe narr...
The string sign may refer to:
angiographic string sign
gastrointestinal string sign
string sign of parosteal osteosarcoma
Stump appendicitis refers to inflammation of the residual appendiceal tissue post appendectomy.
Partial removal of appendix with a residual stump, allows for a chance of recurrent appendicitis. Chances of a partial removal is found to be higher in cases where there is a wrong identification of ...
Subcapsular splenic haematomas are a type of splenic haematoma that occurs beneath the splenic capsule.
They can occur in both traumatic and non-traumatic situations.
abdominal: splenic trauma 3, a subcapsular haematoma is part of imaging criteria for grades I-III of t...
Subdiaphragmatic free gas is one of the ways of detecting presence of free intraperitoneal air (i.e. pneumoperitoneum). It is the presence of free, extraluminal air in the anterior subhepatic space.
Subdiaphragmatic free gas is well appreciated as the a...
The Sudeck point (or Sudeck critical point) refers to a specific location in the arterial supply of the rectosigmoid junction, namely the origin of the last sigmoid arterial branch from the inferior mesenteric artery (IMA) 1.
This arterial branch usually forms an anstomosis with a branch of th...
The superior mesenteric artery (SMA) is one of the three non-paired arteries that provide blood to the midgut and other abdominal viscera.
Single vessel arising anteriorly from the abdominal aorta at the level of L1.
Courses anteroinferiorly, behind the neck of p...
There are two distinct vascular compression disorders due to compression of another structure by the superior mesenteric artery. The terminology is sometimes confusing and they can occur in association.
superior mesenteric artery syndrome (Wilkie syndrome): compression of the third part of th...
Superior mesenteric artery (SMA) syndrome, also known as Wilkie syndrome, is a rare acquired vascular compression disorder in which acute angulation of superior mesenteric artery (SMA) results in compression of the third part of the duodenum leading to obstruction.
It should not be confused wit...
The superior mesenteric vein (SMV) accompanies the superior mesenteric artery (SMA) and drains the midgut to the portal venous system.
Origin and course
Mesenteric venous arcades, which accompany the arteries, unite to form the jejunal and ileal veins in the small bowel mesenter...
The superior rectal artery is an artery that supplies bloods to the rectum down to the level of the levator ani 2.
origin: the terminal branch of the inferior mesenteric artery is the superior rectal artery
course: descends into the pelvic cavity in the sigmoid mesocolon, crossing the...
The supramesocolic space is the peritoneal space above the root of the transverse mesocolon. The inframesocolic space lies below the root of the transverse mesocolon.
It can be arbitrarily divided into right and left spaces and subspaces. These are normally in communication with each other, but...
The supravesical fossae are concave depressions of peritoneum in the paravesical space bounded by the median umbilical fold and the medial umbilical folds. It partially overlies the inguinal (Hesselbach’s) triangle. The supravesical fossae are usually occupied by small bowel loops and the urinar...
Surgical haemostatic material is used to control bleeding intraoperatively and is hence frequently voluntarily left in the operative bed, not to be confused with a gossypiboma which is foreign material left by mistake. It can mimic an abscess on imaging studies. Various types are available, the ...
Syphilis is the result of infection with the gram negative spirochete Treponema pallidum, subspecies pallidum. It results in a heterogeneous spectrum of disease with many systems that can potentially be involved, which are discussed separately.
Despite the discovery of penicillin...
Systemic lupus erythematosus (SLE) is a complex autoimmune disease with multisystem involvement. It is also sometimes classified as a vasculitis.
There is an overall increased female predilection. In adults, women are affected 9-13 times more than males. In children, this ratio i...
The taeniae coli are the three outer muscular bands of the colon. They sit on top of the inner circumferential layer and result in the classical appearance of the colon: the haustral markings are interrupted unlike the valvulae conniventes within the small bowel.
Tailgut duplication cysts, also known as retrorectal cystic hamartomas, are rare congenital lesions that are thought to arise from vestiges of the embryonic hindgut.
There is a recognised strong female predilection. While it can present at any age presentation is usually at aroun...
The Tanaka criteria, also referred as Fukuoka consensus guidelines, is a classification system for intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs).
The prior international consensus guidelines (2006) were referred to as the Sendai criteria. This later evolv...
The target sign of intestinal intussusception, also known as the doughnut sign or bull's eye sign.
The appearance is generated by concentric alternating echogenic and hypoechogenic bands. The echogenic bands are formed by mucosa and muscularis whereas the submucosa is responsible fo the hypoec...
The target sign of pyloric stenosis is a sign seen due to hypertrophied hypoechoic muscle surrounding echogenic mucosa, seen in pyloric stenosis. This is likened to that of a target.
antral nipple sign
cervix sign of pyloric stenosis
shoulder sign of pyloric stenosis
Tc-99m pertechnetate is one of the technetium radiopharmaceuticals used in imaging of thyroid, colon, bladder and stomach.
photon energy: 140 keV
biological half-life: 6 hours
normal distribution: stomach, thyroid, salivary glands, (testicles)
Technetium-99m sulfur colloid is one of the technetium radiopharmaceuticals.
photon energy: 140 keV
physical half-life: 6 hours
bone marrow: 5%
target organ: liver, spleen
Tear drop sign of the superior mesenteric vein (SMV) is one of the important signs in the local staging of pancreatic adenocarcinoma. Its importance lies in its diagnostic, as well as prognostic, significance. This sign is used in assessing the resectability of pancreatic cancer.
Tension gastrothorax describes a rare life-threatening condition caused by mediastinal shift due to a distended stomach herniating into the thorax through a diaphragmatic defect.
Presentation is generally with acute and severe respiratory failure, with clinical features ...
Tension pneumoperitoneum is a special and rare type of pneumoperitoneum, in which the free intra-abdominal peritoneal gas is under pressure. The mechanism is thought to be a ball-valve effect allowing the one-way accumulation of gas. This results in:
elevation and splinting of the diaphragm red...
The differential diagnosis for a terminal ileitis is quite extensive, and includes:
inflammatory bowel disease
Crohn disease (most common)
backwash ileitis due to ulcerative colitis
The terminal ileum is the most distal segment of small bowel. It immediately precedes the small bowel's connection with the colon through the ileocaecal valve. It is of particular interest since a number of infectious and inflammatory processes preferentially involve the segment.
location: the ...
Thumbprinting is a radiographic sign of large bowel wall thickening, usually caused by oedema, related to an infective or inflammatory process (colitis). The normal haustra become thickened at regular intervals appearing like thumbprints projecting into the aerated lumen.
Tissue tropism is a phenomenon by which certain host tissues preferentially support the growth and proliferation of pathogens. This concept is central to the radiological evaluation of infectious disease.
As infections that display tissue tropism will thrive in certain tissue locati...
Toxic megacolon is a complication that can be seen in both types of inflammatory bowel disease, and less commonly in infectious colitis, as well as in some other types of colitis.
Toxic colitis is preferred by many now as the colon is not always dilated.
Toxoplasmosis is a common worldwide parasitic disease caused by the protozoan Toxoplasma gondii. It is usually an asymptomatic infection, but it is related with several sequelae when acquired in-utero or related with cerebral abscesses due to its reactivation in immunocompromised patients (e.g. ...
Tracheo-oesophageal fistula is a pathological communication between the trachea and oesophagus.
It can be broadly classified into two types:
congenital tracheo-oesophageal fistula
acquired tracheo-oesophageal fistula: from malignancy/tuberculosis