A useful mnemonic to help remember the order of structures in the porta hepatis from anterior to posterior is:
D: ducts (right and left hepatic duct branches)
A: arteries (right and left hepatic artery branches)
V: vein (portal vein)
E: epiploic foramen (of Winslow)
The pancreas is a retroperitoneal organ that has both endocrine and exocrine functions: it is involved in the production of hormones (insulin, glucagon and somatostatin), and also involved in digestion by its production and secretion of pancreatic juice.
The pancreas can be divid...
A pancreas transplant is a procedure performed in some medical centers in which a donor pancreas is transplanted to a recipient. The donor pancreas is typically cadaveric, but may rarely be a segment from a living donor 1. The transplant is meant to establish normoglycemia in patients with dia...
Pancreatic atrophy is non-specific and is common in elderly patients, although in younger patients it can be a hallmark of pathology. Most commonly it is associated with aging, obesity and end-stage chronic pancreatitis.
It occurs principally with fatty replacement of the pancreas (pancreatic ...
Pancreatic calcifications can arise form many aetiologies.
Punctate intraductal calcifications
acute alcoholic pancreatitis (20-40%)
intraductal, numerous, small, irregular
preponderant cause of diffuse pancreatic intraductal calcification
idiopathic: no underlying ca...
Both endocrine and exocrine tumours of the pancreas are now staged by a single pancreatic staging system.
Staging of pancreatic ductal adenocarcinoma is with the TNM system, and as a majority of tumours are not-resectable, this is mostly achieved with imaging (typically CT scan) although laparo...
The pancreatic ductal embryology is moderately complicated, leading to a number of anatomical variants of the pancreatic ducts, many of which are clinically significant.
The normal arrangement is for the entire pancreas to be drained via a single duct, to the ampulla of Vater through the sphinc...
Pancreatic intraductal tubulopapillary neoplasms (ITPNs) are rare variants of intraductal papillary neoplasms. Unlike an IPMN, an ITPN does not produce mucin.
Incidence/prevalence is unclear. Small series show an even male:female distribution and an average age of presentation of ...
Pancreatic intraepithelial neoplasia (PanIN) is a precursor lesion to pancreatic ductal adenocarcinoma, but the frequency at which this transition occurs is unknown.
Increasing incidence with age 1. Risk factors:
pancreatic lipomatosis 3
More commonly locat...
Pancreatic lipomas are uncommon mesenchymal tumors of the pancreas.
Rarely symptomatic, they are most often detected incidentally on cross-sectional imaging for another purpose. If they do cause symptoms, it will typically be those related to regional mass effect from the...
Pancreatic lipomatosis refers to fatty replacement of pancreatic parenchyma. This finding is most often associated with obesity and aging.
It tends to be commonest pathological condition involving the pancreas. The condition may occassionally simulate a mass like lesion particularly when fatty...
Pancreatic lymphangiomas are benign lesions that are often found incidentally during cross-sectional imaging for another reason.
More common in adults (in contrast to lymphangiomas in the head and neck, which are more common in children). Account for approximately 1% of a...
Pancreatic lymphoma is most commonly a B-cell sub-type of non-Hodgkin lymphoma and is classified as either primary or secondary:
primary pancreatic lymphoma is a rare extranodal manifestation of any histopathologic subtype of B-cell non-Hodgkin's lymphoma, representing < 2% of extranodal lympho...
Pancreatic mesenchymal neoplasms (or pancreatic nonepithelial neoplasms) are a group of rare pancreatic neoplasms that arise from the structural elements of the pancreas (nerves, fat, lymph), rather than from the exocrine or endocrine cells of the pancreas. Neoplasms from exocrine and endocrine ...
There are numerous primary pancreatic neoplasms, in part due to the mixed endocrine and exocrine components.
Classification based on function
exocrine: ~99% of all primary pancreatic neoplasms
pancreatic ductal adenocarcinoma ~90-95%
intraductal papillary muc...
Pancreatic neurofibromas are rare nonepithelial neoplasms of the pancreas. They are similar to neurofibromas found elsewhere in the body, and are associated with neurofibromatosis type I.
If they do cause symptoms, it will typically be those related to regional mass effe...
Pancreatic perivascular epithelioid cell tumours (or "Pancreatic PEComas") are a subtype of the larger family of PEComas. Pancreatic PEComas are very rare with <20 cases described.
More common in adults (in contrast to lymphangiomas in the head and neck, which are more co...
Pancreatic pseudocysts are common sequelae of acute pancreatitis or chronic pancreatitis, and the most common cystic lesion of the pancreas. They are important both in terms of management and differentiation from other cystic processes or masses in this region.
The following are th...
A number of pancreatic injury grading systems have been proposed.
American Association for the Surgery of Trauma (AAST)
grade 1: haematoma with minor contusion/laceration but without duct injury
grade 2: major contusion/laceration but without duct injury
grade 3: distal lace...
Pancreatic ultrasound can be used to assess for pancreatic malignancy, pancreatitis and its complications, as well as for other pancreatic pathology.
Fast the patient to reduce interference from overlying bowel gas, which may otherwise make visualisation difficult.
Pancreatitis refers to inflammation involving the pancreas.
It has various forms which can be classified in many many ways according to time of onset, aetiological agent or associated pathology.
interstitial oedematous pancreatitis
Pancreatoblastomas are rare paediatric tumours of the pancreas. However, they are the most common pancreatic neoplasm of childhood and are often associated with a raised alpha-fetoprotein.
There is slight male predilection. Usually occurs in the first decade of life with a mean ag...
A pantaloon hernia (dual hernia or Romberg's hernia or saddle bag hernia) is defined as ipsilateral, concurrent direct and indirect inguinal hernias. Hernial sacs are present on both sides of the inferior epigastric vessels, and separated by the posterior wall of the inguinal canal brought down ...
Paraduodenal hernias, although uncommon, are the most common type of internal hernia. The two most common types, the left and right paraduodenal hernia involve small bowel herniating through a congenital opening in the mesenteries. These internal hernias may result in a closed-loop bowel obstruc...
Paraduodenal pancreatitis is an uncommon type of focal chronic pancreatitis affecting the groove between the head of the pancreas, the duodenum and the common bile duct.
The following entities with which it shares clinicopathological features are unified by this term and should no ...
A mnemonic for the common causes of paralytic ileus is:
The classic "5 Ps" are:
P: potassium: low (also disturbances of other electrolytes)
P: pelvic and spinal fractures
However, there are a few further Ps that can be include...
Paraneoplastic syndromes occur secondary to the indirect effects of a malignancy and occur remotely to the primary malignancy. Symptoms are mediated by cytokines, hormones or immune cross-reactivity. These syndromes can cause a diverse range of symptoms and can affect multiple systems.
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.
Can vary and can include:
gastro-oesophageal reflux disease (mai...
Parastomal hernia is defined as the protrusion of abdominal contents through an abdominal wall defect in the vicinity of the stoma.
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...
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.
Paraumbilical hernias are a type of midline ventral abdominal hernia.
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.
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.
superior: lateral umbilical folds
inferior: pubocervical fasc...
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...
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:
Pelvic lipomatosis (also known as pelvic fibrolipomatosis) represents excessive deposition of fat in pelvis due to overgrowth of adipose cells leading to compression of pelvic organs.
The condition usually presents in patients 20-50 years of age. The condition is predominantly (2/...
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...
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 the development of powerful anti-acid medications, peptic ulcer disease h...
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...
A perforated appendix is one of the complications of acute appendicitis. If appendicitis is left untreated, ischemic 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. Perforation o...
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:
pancreatic head / uncinate process tumours: includes pancreatic ductal adenocarcinoma involving head and uncinate process o...
Perianal abscess refers to a formed infective-inflammatory collection within the perianal region. It forms part of the broader group of ano-rectal abscesses.
They are often associated with perianal fistulae and are components of grades 2 and 4 fistulae under the classification system suggested ...
Perianal fistula is a presence of a fistulous tract across the anal sphincters. It is usually an inflammatory condition that affects the region around the anal canal 4.
Incidence is estimated at ~1:10 000 1, with a recognised male predilection of 2-4:1.
The most common...
Pericaecal hernia is a rare type of internal hernia.
It accounts for only 6-13% of internal abdominal hernias.
Four subtypes (ileocolic, retrocaecal, ileocaecal, and paracaecal) of herniations occur in the pericaecal fossa (located behind the caecum and ascending colon...
Perineal hernias are rare pelvic hernias, occurring through a defect in the pelvic floor musculature.
More common in females, with peak age of presentation between 40 and 60 years.
Perineal hernias are classified as anterior or posterior depending on their relationshi...
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.
The perineum is bounded by the pubis anteriorly, the ischial tu...
Peripancreatic pseudoaneurysm refers to the formation of a pseudoaneurysm around the pancreatic gland. It is a rare but potentially lethal complication 5.
Formation of pseudoaneurysm can occur in as many as 10% of cases of pancreatitis. The time interval is variable, ranging from ...
The periportal free gas sign has been described as being strongly suggestive for upper gastrointestinal hollow viscus perforation.
bowel perforation (summary)
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.
It is a multi-laminated structure which is fused posteromedially with the muscular fasciae of the psoas and quadratus lumborum muscle...
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...
Perisplenitis is acute inflammation of the splenic capsule and its peritoneal covering.
It is seen uncommonly but there is no data on its actual incidence.
It is seen usually in young and middle-aged patients, with acute left hypochondrial or lower chest pa...
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
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.
The wall is composed of fibrous tissue without an epithelial l...
Peritoneal hydatidosis occurs secondary to seeding of echinococcosis to the peritoneum, usually secondary to rupture of hydatid disease of liver.
Seeding involves the entire peritoneum and gives appearance of an multiloculated mass.
Peritoneal hydatidosis can be pri...
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
Peritoneal ligaments of the stomach
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 sub-types (also discussed separatel...
Peritoneal metastases, which if of epithelial origin, as most are, and extensive are also known as peritoneal carcinomatosis, are relatively common particularly in tumours of the abdomen and pelvis and generally imply a poor prognosis, often with a significant impact on palliation 1. Less common...
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...
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...
Perivascular epithelioid cells tumours (PEComas) are a group of related mesenchymal tumours and tumour-like conditions found in many locations. This group includes:
clear cell 'sugar' tumour of the lung
clear cell myomelanocytic tumour (CCM...
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 ...
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.
The goal of a peroral pneumocolon is to create a double contrast study (oral contrast and air) of the ascending colon and termina...
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). F-18 is an unstable radioisotope and has a half-life of approx...
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...
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
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).
The ampulla is more ...
Plummer-Vinson syndrome, also known as the Paterson-Brown-Kelly syndrome, predisposes to hypopharyngeal squamous cell carcinoma and consists of four features:
oesophageal webs or hypopharyngeal webs
The condition is more common in women.
Pneumatosis coli is a descriptive sign presenting radiographically as intramural gas limited to the colonic wall.
There are different terminologies in the medical literature, such as pneumatosis intestinalis, pneumatosis coli, and pneumatosis cystoides intestinalis. Pneumatosis in...
A helpful mnemonic for remembering the causes of pneumatosis intestinalis is:
C: chronic obstructive pulmonary disease
P: pneumatosis cystoides intestinalis
Pneumoperitoneum describes gas within the peritoneal cavity, and is often the harbinger of a critical illness. There are numerous causes and several mimics (see article: pseudopneumoperitoneum).
The most common cause of pneumoperitoneum is from the disruption of the wall of a hollow ...
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 may be mimicked by other causes (pseudopneumoperitoneum).
Pneumoretroperitoneum is by definition presence of gas within the retroperitoneal space. It is always abnormal and has a relatively small differential:
perforated retroperitoneal hollow viscus
peptic ulcer disease
blunt or penetrating abdominal trauma
endoscopy +/- biopsy (rare) 3...
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 mint sweet, the polo, also referre...
Polyglandular autoimmune syndromes (PAS) are a rare set of diseases characterised by the presence of ≥2 autoimmune endocrine disease.
Three types of PAS have been described.
PAS type I
a.k.a. APECED (autoimmune polyendocrinopathy, candidiasis and ectodermal dystrophy) or MEDAC (mu...
The polyposis syndromes are disorders in which more than 100 gastrointestinal polyps are present throughout the GI tract:
hereditary nonpolyposis colorectal cancer
familial adenomatous polyposis syndrome (FAPS)
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.
Polysplenia is seen predominantly in female patients. It is usually diagnosed in childhood or adulthood, later than a...
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...
Portal vein calcification is a rare radiologic finding which can be seen in long-standing portal venous hypertension.
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...
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...
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...
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...
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.
The ratio is determined using the following e...
The posterior pararenal space is the smallest and most clinically insignificant portion of the retroperitoneum.
It is filled with fat, blood vessels and lymphatics, but contains no major organs.
posteriorly: bound by transversalis fascia
anteriorly: bound by posteri...
Post transplant lymphoproliferative/lymphoproliferation disorder (PTLD) is increasing in prevalence as the number and survival length of solid organ and bone-marrow transplant recipients also increases.
It represents a variety of conditions varying from lymphoid hyperplasia to malignancy but is...
PPP syndrome is the extremely rare association of pancreatitis, panniculitis, and polyarthritis.
Most commonly affects middle-aged male patients with a history of heavy alcohol use 1,2.
In the majority of cases, abdominal symptoms are mild or absent, makin...
The presacral space is located between the rectum and the sacrococcygeal part of the spine.
The presacral space contains a variety of tissue:
superior - peritoneal reflections
inferior - ...
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),...
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...
Primary peritoneal neoplasms comprise of an uncommon group of heterogenous entities.
The list includes:
primary (malignant) peritoneal mesothelioma
primary perioneal multicystic mesothelioma
primary peritoneal well differentiated papillary mesothelioma
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.
Primary pneumatosis i...
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%).
The most common age for presentation is 40-50 years.
Frequently tumours have relative...
A primary serous papillary carcinoma of the peritoneum (PSPCP) is an extremely rare primary peritoneal tumour.
They usually present in postmenopausal women.
Patients tend to present with non-specific complaints such as abdominal pain, anorexia, and abdomina...
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.
The properitoneal fat pad is known as a plane in surgical anatomy, a...
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...