Peritoneum

Question 1

Which of the following is the hallmark of Sclerosing mesenteritis on CT?

A. Increased density of mesenteric fat to 40-60 HU

B. Collateral vessel formation

C. Fatty nectrotic cystic mass formation

D. Calcification within fat necrosis

E. Mesenteric lymph node enlargement > 10mm

Answer 1

A. Increased density of mesenteric fat to 40-60 HU

An increased attenuation of mesenteric fat (typically 40-60HU) is typical in sclerosing mesenteritis on CT.

Question 2

Which of the following favours pseudomyxoma peritonitis over sclerosing encapsulating peritonitis?

A. Loculated fluid collection

B. Scalloping of the liver edge

C. Peritoneal calcification

D. Tethering of small bowel loops

E. Peritoneal enhancement

Answer 2

B. Scalloping of the liver edge

Pseudomyxomaperitoneiis indicated by ascites and low attenuation masses. The ascites containsseptae, which are the margins of mucinous nodules, typically scalloping the liver edge. Solid non-mucin-producing components cause soft tissue thickening of the peritoneal surface.

Question 3

13 months post-Roux-en-Y bariatric gastric bypass surgery a 45-year-old woman presents with abdominal pain, vomiting and constipation. Abdominal X-ray shows small bowel obstruction (SBO) on CT. Which is the most likely cause of the SBO if the site of the obstruction is in the alimentary limb?

A. Jejenojejunostomy stricture

B. Internal hernia

C. Intraluminal haematoma

D. Intussusception of the Roux limb

E. Mesocolic haematoma

Answer 3

D. Intussusception of the Roux limb

Other options occur < 12 months, whereas internal hernias and mesocolic constriction of the Roux limb are more chronic complications.

Chronic complications with obstruction at the biliopancreatic limb, internal hernias and anastomotic strictures at the common channel are internal hernias and adhesions.

Question 4

Which is most correct regarding internal hernia after bariatric laparoscopic Roux-en-Y gastric bypass?

A. Occur more frequently in open than laparoscopic procedures

B. The obstruction commonly occurs in the efferent limb

C. Incidence of SBO secondary to internal lesions 0.2-5%

D. Physical examination detects the problem with high sensitivity

E. Following Roux-en-Y gastric bypass, the stomach should be relatively distended/fluid filled

Answer 4

C. Incidence of SBO secondary to internal lesions 0.2-5%

Hernia more common in laparoscopic approaches occur in the mesocolic, Peterson’s and mesomesenteric defects.

Obstruction commonly occurs in the afferent (biliopancreatic) limb causing distension of the very proximal jejunum, duodenum and remnant stomach.

Remnant stomach should be relatively decompressed

Question 5

1. A 65-year-old man presents with a several-week history of lower abdominal pain and diarrhoea. On examination he has tenderness and guarding in the left lower quadrant. On contrast-enhanced CT, the inferior mesenteric vein is dilated, with a thin rim of enhancement around a central area of low density. What is the most likely additional pathology demonstrated on the CT?

A. pancreatic pseudocysts

B. ascites due to liver cirrhosis with portal hypertension

C. peritoneal metastases

D. pseudomyxoma peritonei

E. peritoneal mesothelioma

Answer 5

D. pseudomyxoma peritonei

Pseudomyxomaperitonei results from rupture of a benign or malignant mucin producing tumour, most commonly of the appendix or ovary, but also of the pancreas, stomach and colon. Typical findings are of large-volume mucinous ascites, which appears on CT as very low-attenuation (mucinous) fluid collections in the omentum, mesentery and peritoneal cavity, often loculated and containing curvilinear or punctuate calcifications. A characteristic feature is scalloping of the contour of the liver and splenic margins, which distinguishes mucinous from serous ascites.

Peritoneal metastases may also demonstrate loculated peritoneal fluid collections, but there are typically nodular peritoneal densities and thickening of the greater omentum (omental cake).

Peritoneal mesothelioma usually presents with thickened mesentery, omentum, peritoneum and bowel wall, with a disproportionately small amount of ascites.?

Question 6

2. Which anatomical structure separates the right and left subphrenic spaces?

A. gastrohepatic ligament

B. foramen of Winslow

C. falciform ligament

D. Morison’s pouch

E. lesser omentum

Answer 6

C. falciform ligament

The right subphrenic space is in communication around the liver with the anterior subhepatic and posterior subhepatic (Morison’s pouch) spaces.

The right subphrenic and subhepatic spaces communicate freely with the right paracolic gutter and via this with the pelvic peritoneal cavity.

The left subphrenic space communicates with the left subhepatic space but is separated from the right subphrenic space by the falciform ligament and from the left paracolic gutter by the phrenicocolic ligament.

The falciform ligament is a sickle-shaped fold of peritoneum that attaches the ventral surface of the liver to the anterior abdominal wall. It extends in a parasagittal plane from the umbilicus to the diaphragm and carries the ligamentum teres in its free inferoposterior margin.

The lesser sac is an isolated peritoneal compartment between the stomach and pancreas, which communicates with the rest of the peritoneal cavity (greater sac) onlythrough the foramen of Winslow (epiploic foramen). The lesser omentum is composed of the gastrohepatic and hepaticoduodenal ligaments and suspends the stomach and duodenal bulb from the inferior liver surface.

Question 7

3. A 74-year-old man presents with severe abdominal pain and is admitted under the surgical team with suspected perforation. He is too unwell to undergo an erect chest radiograph. What is the most appropriate alternative plain film to detect the presence of free intraperitoneal gas?

A. supine chest

B. erect abdomen

C. supine abdomen

D. left lateral decubitus abdomen

E. right lateral decubitus abdomen

Answer 7

D. left lateral decubitus abdomen

An erect chest radiograph is best for demonstrating a small pneumoperitoneum, enabling the identification of as little as 1 ml of free intraperitoneal gas. It is superior to an erect abdomen, as the X-ray beam penetrates the diaphragmatic regional most tangentially, whereas, in an erect abdomen, the divergent beam penetrates this area obliquely. However, if the patient is too unwell to sit erect, the most appropriate projection is a left lateral decubitus abdominal radiograph, performed with the patient lying on the left side, using a horizontal X-ray beam. In this position, air will preferentially leave a perforated duodenal or antral ulcer, and any free gas in the lesser sac will enter the main abdominal cavity. The supine abdominal radiograph may demonstrate free gas in about 56% of patients with pneumoperitoneum. Characteristic features include gas outlining both inner and outer walls of a bowel loop (Rigler’s sign), triangular collections of gas between bowel loops, and outlining of the falciform ligament and other peritoneal reflections by free gas. The supine chest radiograph is not useful in thedetection of free intraperitoneal gas.

Question 8

5. A 68-year-old woman presents with small bowel obstruction, and undergoes contrast-enhanced CT of the abdomen. This demonstrates dilated small bowel to the level of the mid-ileum, where a herniated loop of small bowel is seen emerging inferolateral to the left pubic tubercle. What is the most likely cause of small bowel obstruction in this patient?

a. femoral hernia

b. indirect inguinal hernia

c. direct inguinal hernia

d. spigelian hernia

e. obturator hernia

Answer 8

a. femoral hernia

External hernias are the second most common cause of small bowel obstruction after adhesions.

A femoral hernia protrudes through the femoral ring, lying medial to the femoral vein, which may be compressed. On CT the hernia is seen inferolateral to the pubic tubercle, in contrast to inguinal hernias, which usually lie superomedial to the tubercle, though differentiation may be difficult in non-incarcerated cases.

Femoral hernias are more prone to incarceration due to the inflexible margins of the femoral ring.

Inguinal hernias may be classified as indirect (passing down the inguinal canal, seen lateral to the inferior epigastric vessels) or direct (protruding directly through the lower abdominal wall medial to the inferior epigastric vessels).

A spigelian hernia protrudes through a defect in the inferolateral anterior abdominal wall.

Obturator hernias protrude through the obturator foramen, between the pectineus and external obturator muscles.

Question 9

A 77-year-old man presents with abdominal distension. A CT study of his abdomen and pelvis reveals nodular peritoneal thickening, omental cake and a stellate appearance within the mesentery. Some foci of calcification are evident. What is the most likely diagnosis?

(a) Tuberculosis

(b) Lymphoma

(c) Carcinoma

(d) Pseudomyxoma

(e) Mesothelioma

Answer 9

16 (e) Mesothelioma

These are typical features of sarcomatous mesothelioma. Peritoneal mesothelioma represents 6-10% cases of mesothelioma, with 50% cases having had previous asbestos exposure. Radiation therapy also predisposes to this condition, which affects visceral and parietal peritoneum.

Question 10

@# 18 A patient is referred for a CT of the chest, abdomen and pelvis, the clinical details read “Riedel’s thyroiditis. Hyper- IgG4 disease”. Are any other organs involved? Which of the following conditions are not associated?

(a) Cryptogenic organising pneumonia

(b) Benign pleural mesothelioma

(c) Systemic sclerosis

(d) Autoimmune pancreatitis

(e) Retroperitoneal fibrosis

Answer 10

(c) Systemic sclerosis

Hyper lgG4 is a chronic inflammatory condition that may involve a number of organs. It is characterized histologically by a lymphoplasmacytic inflammation with lgG4-positive cells and. exuberant fibrosis, which leaves dense fibrosis on resolution. It may respond to corticosteroids or other immunosuppressant therapy. Sclerosing sialadenitis, retro-orbital pseudotumour, and panniculitis.

Question 11

@# (GU) 40 With regards to the anatomy of the retroperitoneum, which of the following statements is true?

(a) The right perirenal space communicates with the bare area of the liver

(b) The left perirenal space communicates with the scrotum

(c) The adrenal gland is in the anterior pararenal space

(d) The psoas muscle is in the posterior pararenal space

(e) The posterior pararenal space contains the ascending and descending colon

Answer 11

(a) The right perirenal space communicates with the bare area of the liver

The psoas lies posterior to the posterior pararenal space.

The adrenal gland is in the perirenal space.

The ascending and descending colon are in the anterior pararenal space.

Question 12

50 A 76-year-old man with a clinical suspicion of a hernia is referred for an US. A colleague performs the study and reports: “The hernia lies lateral to conjoint tendon and medial to inferior epigastric artery at inferior aspect of Hesselbach’s triangle.” What type of hernia is described?

(a) Direct inguinal hernia

(b) Spigelian hernia

(c) Hypogastric hernia

(d) Femoral hernia

(e) Obturator hernia

Answer 12

(a) Direct inguinal hernia

Direct inguinal hernias originate infero-medial to the inferior epigastric artery,

whilst indirect originate supera-laterally.

Spigelian hernias lie at the line a semilunaris,

hypogastric hernias lie in the midline below the umbilicus

and femoral hernias pass through the femoral canal.

Question 13

A 56-year-old lady upper abdominal pain is referred for a CT of the abdomen and pelvis. This shows abnormal loop of small bowel passing between the portal vein and IVC. What type of internal hernia is this?

(a) Foramen of Winslow

(b) Left paraduodenal

(c) Transesenteric

(d) Right paraduodenal

(e) Inter-sigmoid

Answer 13

(a) Foramen of Winslow

The loop of bowel passes through the foramen of Winslow in to the lesser sac. Left paraduodenal hernias pass through a defect in the descending mesocolon and lie to the left of the 4th part of the duodenum. The rarer right paraduodenal hernia passes behind the SMA and is associated with malrotation. Transmesenteric hernias are commoner following surgery.

Question 14

A 78-year-old lady presents to A&E small bowel obstruction. A CT study demonstrates the transition point to be a loop of small bowel lying immediately behind the pectineus muscle. What is the diagnosis?

(a) Perineal hernia

(b) Sciatic hernia

(c) Inferior lumbar triangle hernia

(d) Femoral hernia

(e) Obturator hernia

Answer 14

(e) Obturator hernia

The pectineus muscle is the anterior border of the obturator canal, with the obturator externus the posterior margin. Bowel is commonly obstructed with this type of hernia, often seen in elderly patients.

Question 15

(GU) 18. A 28 year old woman suffers blunt injury to her abdomen following a road traffic accident. A polytrauma CT scan does not demonstrate any intra-abdominal injuries, but there are features indicating retroperitoneal injuries. Regarding these features, which of the following is true?

a. Retroperitoneal air may indicate pulmonary injuries

b. Haematomas in the posterior pararenal space do not extend into the pelvis

c. The most common region demonstrating retroperitoneal haemorrhage following trauma is usually around the aorto-caval region in the midline

d. Adrenal injuries are more common on the left

e. Low-attenuation fluid (<–20 HU) in the retroperitoneum is always indicative of injury to the pelvi-calyceal system or the ureters

Answer 15

18. a. Retroperitoneal air may indicate pulmonary injuries

Air in the retroperitoneum can follow pneumothorax. However, in the absence of pneumothorax, it is strongly indicative of duodenal/colonic injury. The posterior and anterior pararenal spaces communicate freely with the pelvic retroperitoneum, whilst the perinephric space is enclosed. The retroperitoneum is divided into three zones: I – midline retroperitoneum; II – lateral retroperitoneum; and III – pelvic retroperitoneum. Zone III is the commonest site for haematoma following blunt injury. Adrenal injuries are more common on the right. Low-attenuation fluid can be seen even in the absence of urine leak, usually indicating hypoperfusion shock syndrome.

Question 16

25. A one year old boy is admitted unwell with generalised abdominal tenderness and guarding. A supine plain abdominal film is requested, which shows a large oval radiolucency in the middle of the abdomen, with a well-defined linear opacity in the right upper quadrant. Which one of the following conditions would best explain these appearances?

a. Enteric duplication cyst

b. Choledocal cyst

c. Pneumoperitoneum

d. Duodenal atresia

e. Caecal volvulus

Answer 16

25. c. Pneumoperitoneum

Whilst uncommon, the appearances seen on plain film are consistent with massive pneumoperitoneum. The oval radiolucency is called the ‘football sign’ and arises due to free air collecting anterior to the intra-abdominal viscera. This sign is only seen in 2% of adults with pneumoperitoneum due to the large quantities of air required to produce it. It is much more common in infants who may present at a later stage. The opacity in the right upper quadrant is produced by air outlining the falciform ligament, which again is a sign of pneumoperitoneum. Causes of perforation in this age group include trauma, intussusception and complications of Meckel’s diverticulum.

Question 17

40. A 50 year old female presents to A&E with acute abdominal pain. On examination there is point tenderness over an area in the right iliac fossa. CT reveals a well-defined triangular area of high-attenuation fat density anteriorly in the lower right abdomen. The large and small bowel are normal. Which one of the following is most likely?

a. Segmental omental infarction

b. Rectus haematoma

c. Epiploic appendagitis

d. Carcinoid tumour

e. Mesenteric vein thrombosis

Answer 17

40. a. Segmental omental infarction

Segmental omental infarction is the most likely cause and most commonly affects the right half of the greater omentum. It mimics surgical pathology such as appendicitis. High attenuation streaks in the omental fat with apparent ‘mass effect’ in the absence of any other findings is suggestive of the diagnosis. Point tenderness over the specific area of CT abnormality is often discovered. Management is conservative.

Question 18

46. A 48 year old male presents with abdominal pain, nausea and weight loss. Contrast-enhanced CT of the abdomen and pelvis reveals a heterogeneous, well-defined fatty mass at the root of the small bowel mesentery. The mesenteric vessels are surrounded but not distorted by the mass, and the vessels are surrounded by an apparent low-attenuation halo. The small bowel and right colon are normal. Which is the most likely diagnosis?

a. Tuberculosis

b. Mesenteric lymphadenitis

c. Mesenteric panniculitis

d. Radiation enteritis

e. Mesenteric lipoma

Answer 18

46. c. Mesenteric panniculitis

These CT findings are typical of mesenteric panniculitis. This is an idiopathic, indolent condition characterised by inflammation of the small bowel mesentery adipose tissue. Fibrosis can predominate, in which case the CT appearances are of an infiltrative soft-tissue mass with soft-tissue density strands radiating away from it. In this situation it has similar appearance to lymphoma, carcinoid or desmoidtumours or retroperitoneal fibrosis, and biopsy is required to differentiate. Mesenteric panniculitis often presents with non-specific symptoms such as abdominal pain, weight loss, nausea, vomiting and pyrexia, and is usually indolent and self-limiting.

Question 19

(MSK) 50. A 27 year old woman is brought into A&E following a road traffic accident in which she was knocked down by a car. On arrival she has a GCS of 15 but is haemodynamically unstable and on examination she has abdominal bruising. The A&E consultant has performed a FAST (focused assessment with sonography in trauma) scan in resus and cannot see evidence of free fluid. What is the approximate minimal detectable fluid volume by FAST scanning?

a. 10 ml

b. 50 ml

c. 100 ml

d. 200 ml

e. 500 ml

Answer 19

50. d. 200 ml

The approximate minimal detectable fluid volume is 200 ml. The distribution of free fluid will be determined by both anatomical and physiologic factors and therefore the sensitivity of the scan will depend upon the areas scanned. Ultrasound is often used in conjunction with multidetector CT, particularly in the management of patients who have been involved in trauma.

Question 20

QUESTION 34
A 46-year-old woman from Bangladesh is being treated for pulmonary tuberculosis. Despite anti-tuberculosis chemotherapy, she develops increasing fevers with abdominal discomfort and distension. An abdominal and pelvic ultrasound demonstrates a moderate volume of peritoneal free fluid, and acontrast-enhanced CT of the abdomen and pelvis is performed. What are the likely findings on CT?

A A mixed solid:cystic ovarian mass with serosal deposits on the liver and spleen

B Ascites with enlarged mesenteric lymph nodes containing high attenuation centres

C Gastric wall thickening extending into the spleen with enlarged celiac axis lymph nodes and ascites

D Peritoneal nodularity with high density ascites

E Portal vein thrombosis with ascites

Answer 20

D Peritoneal nodularity with high density ascites

In peritoneal TB, the presence of dense ascites, peritoneal nodularity and lymph nodes with low attenuation centres are characteristic findings.

Question 21

QUESTION 61
A 32-year-old woman undergoes a laparoscopic cholecystectomy for gallstones. Seven days later, she presents to the Emergency Department with increasing abdominal pain and fevers. On examination, her temperature is 39.6°C, HR =100 bpm and BP = 110/60 mmHg with tenderness and guarding in the right upper and lower quadrants of the abdomen. Laboratory investigations reveal a grossly elevated CRP level and white cell count. The clinical team request a contrast-enhanced CT for suspected intra-abdominal sepsis. Which statement is true regarding intra-abdominal fluid collections?

A Fluid in the lesser sac communicates freely with the left subphrenic space.

B Fluid in the right paracolic gutter communicates freely into the pelvis and superiorly to the right subdiaphragmatic space.

C Fluid in the right paracolic gutter will be bounded superiorly by the phrenic colic ligament.

D Postoperative gallbladder collections usually lie in the right infra colic space.

E The right subphrenic space is also called ‘Morrison’s pouch’.

Answer 21

B Fluid in the right paracolic gutter communicates freely into the pelvis and superiorly to the right subdiaphragmatic space.

The right paracolic gutter communicates freely with the right perihepatic space (bounded by the falciform ligament). Postoperative gallbladder collections will tend to lie in the gallbladder fossa and the hepatorenal recess (also known as Morrison’s pouch).

Question 22

A 54-year-old man presents with persistent abdominal pain and fever. His amylase has been normal, and colonoscopy and small bowel series were unremarkable during previous investigation. He has a past medical history of thyroid disease. A CT of abdomen reveals ill-defined rounded areas in the root of the mesentery, with adjacent mild lymphadenopathy. There is some central calcification. A rim of preserved fat is seen surrounding the adjacent vessels. What is the most likely diagnosis?

A. Sclerosing mesenteritis.

B. Desmoid tumour.

C. Carcinoid tumour.

D. Lymphoma.

E. Metastatic disease.

Answer 22

A. Sclerosing mesenteritis.

This is a rare condition of unknown cause characterized by chronic mesenteric inflammation. It is most frequently seen in the sixth decade and more commonly in males than females. It is often associated with other inflammatory disorders such as retroperitoneal fibrosis, Riedel thyroiditis, and sclerosing cholangitis. Symptoms include abdominal pain, nausea, fever, intestinal obstruction or ischaemia, a mass, or diarrhoea. The CT findings can range from subtle increased attenuation in the mesentery to a solid soft-tissue mass. The mass may envelop vessels, but there may be preservation of fat around the vessels, the ‘fat halo’ sign. This finding may help distinguish sclerosing mesenteritis from other mesenteric processes such as lymphoma, carcinomatosis, or carcinoid tumour. Calcification may be present, usually in the central necrotic portion. Enlarged mesenteric or retroperitoneal lymph nodes may also be present. Lymphoma will not display calcification unless it has undergone treatment. Carcinoid can produce the appearance described, but the ‘fat halo’ sign favors sclerosing mesenteritis and the soft tissue in carcinoid usually has a surrounding desmoplastic reaction. Metastatic disease will not be confined to the root of the mesentery, but will also involve the omentum or the surfaces of the liver, spleen, or bowel. Ascites is also common with carcinomatosis, but is not associated with sclerosing mesenteritis. Mesenteric involvement in the case of desmoid tumours is more often seen in cases related to familial adenomatous polyposis syndrome or Gardner syndrome. They are usually large masses, measuring 15 cm or more at diagnosis. They do not typically contain calcification.

Question 23

A 26-year-old man, with a previous history of a panprocto-colectomy for Gardner’s syndrome, presents with vague abdominal discomfort and a CT scan is requested to ascertain the cause. He is found to have a well-defined mass of homogenous density, which you suspect may be a desmoid tumour, given the previous clinical history. Where in the abdomen is this most likely to be located?

A. Abdominal wall.

B. Retroperitoneum.

C. Small bowel mesentery.

D. Pelvis.

E. Duodenal wall.

Answer 23

C. Small bowel mesentery.

Desmoid tumours are non-malignant fibrous tumours that have a particular association with FAP/Gardner syndrome. They may be locally infiltrative. On CT they are usually of homogeneous density, but can have well-defined or irregular margins. On MRI, the signal intensity on T1WI is similar to muscle and on T2WI their signal can be variable. Lower signal tumours on T2WI probably have a denser fibrous component. Desmoid tumours in association with FAP/Gardner syndrome are most commonly seen in the small bowel mesentery, followed by the abdominal wall. Intra-abdominal desmoid tumours can also occur in the retroperitoneum and pelvis, but these locations are more common in isolated desmoids.

Question 24

14. Which one of the following is false regarding peritoneal and mesenteric structures?

A. The lesser sac communicates with the rest of the abdominal cavity through the foramen of Winslow.

B. The left paracolic gutter communicates with the left subphrenic space.

C. The falciform ligament connects to the left coronary ligament.

D. Part of the duodenum is suspended in the lesser omentum.

E. The right paracolic space communicates with the pouch of Douglas.

Answer 24

14. B. The left paracolic gutter communicates with the left subphrenic space.

There is no direct connection between these two spaces due to the phrenico-colic ligament. The rest of the statements are correct.

Question 25

42. A 45-year-old man presents with acute abdominal pain. He has pyrexia and his inflammatory markers are raised. The surgical team request a CT scan of abdomen for ‘?perforation’. The CT reveals inflammatory change in the anterior pararenal space. Which of the following is least likely to be the underlying cause for the CT finding?

A. Acute pancreatitis.

B. Gastric ulceration.

C. Diverticulitis of the descending colon.

D. Duodenal perforation.

E. Perforation of ascending colon due to neoplasm.

Answer 25

42. B. Gastric ulceration.

The anterior pararenal space extends between the posterior parietal peritoneum and the anterior renal fascia (Gerota’s fascia). It is bounded laterally by the lateral conal fascia. The pancreas, second and third parts of the duodenum, and ascending and descending colon are located within the anterior pararenal space, and disease in this space usually arises in these organs. The stomach is intraperitoneal.

Question 26

54. A 55-year-old man with a previous history of liver transplantation presents with a 1-week history of abdominal pain and distension. An AXR shows some distended small bowel loops centrally within the abdomen. You are asked to perform a CT scan of abdomen for further evaluation. This shows a cluster of non-encapsulated dilated small bowel loops adjacent to the anterior abdominal wall on the right side. There are adjacent crowded mesenteric vessels. What is the most likely diagnosis?

A. Small bowel adhesions.

B. Left paraduodenal hernia.

C. Right paraduodenal hernia.

D. Foramen of Winslow hernia.

E. Transmesenteric hernia.

Answer 26

54. E. Transmesenteric hernia.

This is when small bowel herniates through a defect in the mesentery and is compressed against the abdominal wall, with little overlying omental fat at most levels of anatomic section through the herniated bowel. There will be some degree of compression, crowding, displacement, and obstruction of both the bowel and blood vessels. They are usually seen in association with previous abdominal surgery and the creation of a Roux-en-Y anastomosis, when the hernia occurs in a surgically created defect in the mesentery. A left-sided paraduodenal hernia is via the paraduodenal (lateral to the fourth part) mesenteric fossa of Landzert, close to the ligament of Treitz. The characteristic features include a sac-like mass of dilated bowel lateral to the ligament of Treitz, which displaces and indents the adjacent stomach and transverse colon.
A right paraduodenal hernia occurs via the jejunal mesentericoparietal fossa of Waldeyer. A cluster of dilated small bowel loops is seen lateral and inferior to the descending duodenum.

Question 27

44. A 67-year-old man presents to A&E with abdominal pain. Inflammatory markers are raised, but serum electrolytes, amylase, haemoglobin, and coagulation are normal. He takes no regular medication. On examination, there is a palpable mass in the right lower quadrant. CT reveals a lobulated, hypoattenuating mass with thick walls, septa, and curvilinear calcifications. It is located in the RIF, and displaces and distorts the adjacent psoas muscle. What is the most likely diagnosis?

A. Pancreatic pseudocyst.

B. Pseudomyxomaretroperitonei.

C. Urinoma.

D. Haematoma.

E. Retroperitoneal liposarcoma.

Answer 27

44. B. Pseudomyxomaretroperitonei

The displacement of the psoas muscle indicates that this mass is most likely retroperitoneal. Pseudomyxomaperitonei is a rare condition that is characterized by intraperitoneal accumulation of gelatinous material owing to the rupture of a mucinous lesion of the appendix or ovary, e.g. mucinous cystadenoma/ cystadenocarcinoma. It may occur in the retroperitoneum, where it is caused by the rupture of a mucinous lesion in the retrocaecal appendix and fixation of the lesion to the posterior abdominal wall. Clinically, it results in abdominal pain and a palpable mass. At CT, it appears as a multicystic mass with thick walls or septa that displace and distort adjacent structures. Curvilinear or punctuate mural calcifications may also occur and are highly suggestive. Pancreatic pseudocysts usually occur in the peripancreatic space, but may occur in the abdomen, pelvis, or mediastinum. They are associated with the clinical findings of pancreatitis and elevation of serum amylase. A urinoma is an encapsulated collection of chronically extravasated urine. There is usually a history of trauma and an associated hydronephrosis. Haematomas are associated with trauma, coagulopathy/anticoagulants, or a ruptured abdominal aortic aneurysm. Chronic haematoma can result in low attenuation contents, but acutely the haematoma will have higher attenuation than pure fluid due to clot formation. Retroperitoneal liposarcoma is most commonly of a density between water and muscle (myxoid type). It may have a solid, mixed, or pseudocystic pattern on CT. There is macroscopic areas of lipid in well-differentiated liposarcomas

Question 28

69 An obese 55-year-old female had a history of abdominal bloating, but no other symptom was investigated. Plain chest and abdominal radiographs were normal. An ultrasound showed a moderate amount of ascites, but the views were limited and a contrast-enhanced CT was arranged which showed gross abdominal ascites with a mean density of 45 HU. No other abnormality was detected. What is most likely to have caused the ascites?

a Budd-Chiari syndrome

b Hypoalbuminaemia

C Meigs syndrome

d Right heart failure

e Unseen ovarian tumour

Answer 28

69 Answer E: Unseen ovarian tumour

The three classical causes of high-density ascites are tuberculosis, ovarian tumour and appendiceal tumour, which produce particularly proteinaceous fluid. Other exudates may also cause ascites of higher density: Meigs syndrome is an exudative process, but no pleural effusion was present. A simple transudate is likely to be of lower attenuation, for example Budd-Chiari syndrome.

Question 29

A 39-year-old male presented with abdominal pain, vomiting and a distended abdomen. A plain abdominal radiograph showed dilated loops of small bowel. He was otherwise well with no previous surgery and his hernial orifices were normal. A contrast-enhanced CT showed an internal encapsulated bowel loop, which was displacing the inferior mesenteric vein. What is the most likely cause for these appearances?

a Right paraduodenal hernia

b Left paraduodenal hernia

c Lesser sac hernia

d Intersigmoid hernia

e Inguinal hernia

Answer 29

Answer A: Right paraduodenal hernia

Rt paraduodenal hernia is the most common internal hernia and classically displaces inferior mesenteric vein.

Question 30

11. A 60-year-old man was admitted with intermittent abdominal pain. CT scan shows an ill-defined soft tissue mass in the bowel mesentery, with extensive calcification within. Strands of soft tissue are seen radiating into the surrounding fatty mesentery. The adjacent bowel loops show retraction. MRI shows low signal on T1 and T2 images. The most likely diagnosis is?

(a) Carcinoid syndrome

(b) Fibrosing mesenteritis

(c) Mesenteric panniculitis

(d) Desmoidtumour

(e) Old tuberculosis

Answer 30

11. (b) Fibrosing mesenteritis

This is the classical appearance for fibrosing mesenteritis.

Question 31

21. A 6-year-old girl presents with gradually increasing abdominal mass. X-ray shows a soft tissue mass displacing bowel loops, with small calcifications. Ultrasound reveals a 10 cm, thin walled, cystic lesion in mid abdomen, with multiple internal septations and small internal echoes. The most likely diagnosis is?

(a) Duplication cyst

(b) Mesenteric cyst

(c) Neuroblastoma

(d) Ovarian cyst

(e) Lymphoma

Answer 31

21. (b) Mesenteric cyst

Mesenteric cysts are rare and are found in the mesentery and omentum. They are true congenital abnormalities and arise due to sequestration of mesenteric lymphatics. Imaging features are typical as given in this case history. CT scan defines the anatomic margins of the cyst but septations are poorly seen on CT. MRI features vary according to the contents of the cyst.

Question 32

23. An 18-year-old involved in a road traffic accident presents at Accident & Emergency Department with abdominal pain. CT shows fat stranding in the SI mesentery. There is small amount of fluid between small bowel folds, with a Hounsfield unit of 75. The diagnosis is?

(a) Mesenteric haematoma

(b) Splenic rupture

(c) Liver laceration

(d) Bowel perforation

(e) Normal free fluid

Answer 32

23. (a) Mesenteric haematoma

Given the history of road traffic accident, high attenuating fluid between the bowel loops is likely to represent mesenteric injury.

Question 33

33. A 60-year-old alcoholic presents with gradual distension of abdomen. He gives a history of surgically treated complicated appendicitis. Ultrasound shows extensive thin-walled cystic masses in abdomen. The most likely diagnosis is?

(a) Ascites

(b) Peritoneal metastases

(c) Pseudomyxomaperitonei

(d) Pancreatic pseudocyst

(e) Pyogenic peritonitis

Answer 33

33. (c) Pseudomyxomaperitonei

This is due to intraperitoneal rupture of an appendiceal or ovarian mucinous adenoma. The ascites is typically septated and there are several thin-walled cystic masses throughout the abdominal cavity.

Question 34

37. A 35-year-old previously fit man presents with abdominal pain and a lump in right lower abdomen. CT shows a hernia just lateral to the right rectus muscle with an obstructed loop of small bowel. What is diagnosis?

(a) Ventral hernia

(b) Spigelian hernia

(c) Umbilical hernia

(d) Hernia through a laparoscopic port

(e) Inguinal hernia

Answer 34

37. (b) Spigelian hernia

This is seen through weakness in the spigelian aponeurosis, which lies between the linea semilunaris laterally and the rectus muscle medially. Ventral hernia is usually midline, through the linea alba.

Question 35

38. A 45-year-old man with a history of laparotomy presents with palpable hard lump in the abdominal wall. CT shows a soft tissue mass with ill-defined margins in the rectus muscle showing mild contrast enhancement. On MRI, the lesion returns low signal on T1 and T2. What is the most likely diagnosis?

(a) Desmoid

(b) Metastasis

(c) Haematoma

(d) Seroma

(e) Lymphoma

Answer 35

38. (a) Desmoid

The lesion is fibrous tissue returning low signal on T1 and T2 sequences. There is usually a history of abdominal surgery and the lesions are ‘rock hard’. Other differentials are unlikely given imaging characteristics.

Question 36

@#e 38. A 60-year-old presents with left groin pain. Ultrasound shows a 2 cm hypoechoic lesion bulging medial to the epigastric vessels on Valsalva manoeuvre and absent on rest. What is the most likely diagnosis?

(a) Direct inguinal hernia

(b) Indirect inguinal hernia

(c) Obturator hernia

(d) Spigelian hernia

(e) Femoral hernia

Answer 36

38. (a) Direct inguinal hernia

A direct inguinal hernia is seen medial to the inferior epigastric vessels whereas an indirect hernia is seen lateral to them.

Question 37

39. A 40-year-old man presents with right groin pain. Ultrasound shows a 3 cm echogenic soft tissue mass distending the right inguinal canal on straining, and which goes away on relaxation. What is the most likely diagnosis?

(a) Direct inguinal hernia

(b) Indirect inguinal hernia

(c) Femoral hernia

(d) Obturator hernia

(e) Lymph node

Answer 37

39. (b) Indirect inguinal hernia

An indirect inguinal hernia protrudes through the internal inguinal ring and extends along the inguinal canal parallel to its long axis.

Question 38

40. A 40-year-old man presents with a lump in the right groin 2 months after a laparoscopic inguinal hernia repair. Ultrasound shows a well-defined homogenous, hyperechoic, avascular soft tissue mass lateral to the inferior epigastric vessels in the right groin. It has no change on pressure or with Valsalva manoeuvre. What is the most likely diagnosis?

(a) Recurrent direct inguinal hernia

(b) Recurrent indirect inguinal hernia

(c) Lymph node

(d) Lipoma

(e) Seroma

Answer 38

40. (d) Lipoma

The lesion has typical sonographic characteristics of a lipoma.

Question 39

16. Regarding peritoneal spaces: (T/F)

(a) The right subhepatic space communicates with the lesser sac.

(b) The left subphrenic space is separated from the right subphrenic space by the falciform ligament.

(c) The bare area of the liver is located between reflections of the right and left coronary ligaments.

(d) The splenorenal ligament separates the left subphrenic space from the left paracolic gutter.

(e) The gastrocolic ligament connects the lesser curve of the stomach to the superior aspect of the transverse colon.

Answer 39

Answers:

(a) Correct
(b) Correct
(c) Correct
(d) Not correct
(e) Not correct

Explanation:

Phrenico-colic ligament separates the left subphrenic space from the left paracolic gutter since it attaches to the
descending colon to the left hemidiaphragm. The gastrocolic ligament connects to the greater curvature of the stomach to the superior aspect of the transverse colon.