Abdomen and pelvis Flashcards
peritoneal cavity is divided into
greater and lesser peritoneal cavity
right subphrenic space communicates with
around the liver, with the anterior subhepatic and posterior subhepatic space
most dependent portion of the abdominal cavityin supine patient and it preferentially collects ascites, hemoperitoneum, metastases and abscesses
Morison pouch (right hepatorenal fossa)
communicates freely with the pelvic peritoneal cavity via the right paracolic gutter
right subphrenic and subhepatic space
left and right subphrenic space are separated by
falciform ligament
left subphrenic space is separated with the left paracolic gutter by the
phrenicocolic ligament
common location for abscesses and for disease process of the tail of pancreas
left subphrenic (perisplenic) space
space that is affected by diseases of the duodenal bulb, lesser curve of stomach, gallbladder and left lobe of liver
left subhepatic space (gastrohepatic recess)
falciform ligament consists of how many layers of peritoneum extending from the umbilicus to the diaphragm in parasagittal plane
2
caudal free end of the falciform ligament contains
ligamentum teres
obliterated umbilical vein
ligamentum teres
vessels within the falciform ligament that enlarges as a specific sign of portal hypertension
paraumbilical veins (portosystemic collateral vessels)
reflections of the falciform ligament separate over the posterior dome of the liver to form the
coronary ligaments
bare area of the liver not covered by peritoneum
coronary ligaments
reflects between the liver and diaphragm and prevent access of ascites and other intraperitoneal process from covering the bare area of the liver
coronary ligaments
lesser omentum is composed of _____ and _____ that suspends the stomach and duodenal bulb from the inferior surface of the liver
gastrohepatic and hepatoduodenal ligaments
separates the gastrohepatic recess of the left subphrenic space from the lesser sac
lesser omentum
lesser omentum contains what vessels
coronary veins
enlarged lymph nodes in gastric carcinoma and lymphoma are seen in
lesser omentum
isolated peritoneal compartment between the stomach and the pancreas
lesser sac
lesser sac communicates freely with the rest of the peritoneal cavity (the greater sac) only through the
small foramen of Winslow
pathologic processes in the lesser sac usually occur in
adjacent organs (pancreas, stomach)
double layer of peritoneum that hangs from the greaster curvature of the stomach and descends in front of the abdominal viscera separating bowel from the anterior abdominal wall
greater omentum
serves as a fertile ground for implantation of peritoneal metastases, and assists in loculation of inflammatory processes of the peritoneal cavity such as abscesses and tuberculosis
greater omentum
extends between the posterior parietal peritoneum and anterior renal fascia
anterior pararenal space
anterior pararenal fascia is bounded by
lateroconal fascia
structures within the anterior pararenal space
pancreas, duodenal loop, ascending and descending portions of the colon
encompasses the kidney, adrenal gland, and perirenal fat within the perirenal space
anterior and posterior renal fascia
the anterior layer of posterior renal fascia is continuous with
anterior renal fascia
the posterior layer of the renal fascia is continuous with the ________ forming the lateral boundary of the anterior pararenal fasica
lateroconal fascia
renal fascia is bound to the fascia surrounding the aorta and vena cava usually to
prevent spread of disease to the contralateral perirenal space
the right perirenal space is open ____ allowing spread of disease between the kidney and liver
superior
potential space, usually filled only with fat, extending from the posterior renal fascia to the transversalis fascia
posterior pararenal space
isolated fluid collections are rare in the posterior pararenal space and is most commonly caused by
spontaneous hemorrhage into the psoas muscle as a result of anticoagulation therapy
3 major anatomic compartments of pelvis
peritoneal cavity, extraperitoneal space and perineum
this part of the pelvis extends to the level of the vagina, forming the pouch of Douglas (cul-de-sac) in females, or the level of seminal vesicles, forming the rectovesical pouch in males
peritoneal cavity
serves as the anterior boundary of the rectouterine pouch of Douglas, and reflects over the uterus, fallopian tubes, and parametrial uterine vessels
broad ligament
most dependent portion of peritoneal cavity and collects fluid, blood, abscesses and intraperitoneal drop metastases
cul-de-sac
part of pelvis that is continuous with the retroperitoneal space of abdomen, extends to the pelvic diaphragm, and includes the retropubic space (of Retzius)
extraperitoneal space of pelvis
part of pelvis that lies below the pelvic diaphragm
perineum
anatomic landmark of perineum
ischiorectal fossa
conventional radiographic diagnosis of ascites requires at least how many cc of fluid to be present
500 cc
radiographic findings of ascites
diffuse decrease in density (gray abdomen), indistinct margins of liver, spleen and psoas muscles, medial displacement of gas-filled colon, liver and spleen away from the properitoneal flank stripe, bulging of flanks, increased separation of gas-filled small bowel loops, and dog ears appearane of symmetric densities in the pelvis due to fluid spilling out of the cul-de-sac on either side of bladder
serous ascites has attenuation values of
near water (-10 to +10 HU)
exudative ascites has attenuation values of
above 15 HU
acute bleeding into peritoneal cavity has attenuation value of
45 HU
refers to gelatinous ascites that occurs as a result of intraperitoneal spread of mucin-producing cells resulting from rupture of appendiceal mucocele or intraperitoneal spread of benign or malignant mucinous cysts of the ovary or mucinous adenocarcinoma of the colon of rectum
pseudomyxoma peritonei
appearance of pseudomyxoma peritonei in radiographs
punctate or ring-like calcifications scattered through the peritoneal cavity
ct appearance of pseudomyxoma peritonei
mottled densities, septations, and calcifications within the fluid
ultrasound appearance of pseudomyxoma peritonei
intraperitoneal nodules that range from hypoechoic to strongly echogenic
most common cause of pneumoperitoneum
duodenal or gastric ulcer perforation
postoperative pneumoperitoneum usually resolves in
3 to 4 days
positioning that may be used with very ill patients to demonstrate air outlining the liver
left lateral decubitus and cross-table lateral views
signs of pneumoperitoneum on supine radiographs include
gas on both sides of the bowel wall (Rigler sign), gas outlining the falciform ligament, gas outlining the peritoneal cavity (football sign), and triangular or linear localized extraluminal gas in the RUQ
aneuryms of aorta are manifest by luminal diameter exceeding ___ as measured between calcifications in the aortic wall
3 cm
right-like calcified aneurysms most commonly involve the
splenic or renal arteries
calcified thrombi in veins most commonly visualized in the lateral aspects of the pelvis
phleboliths
phleboliths are round or oval calcifications up to ___ mm in size that commonly contain a central lucency
5 mm
most calcified gallstones contain
calcium bilirubinate
how many percent of gallstones contain sufficient calcium to be identified on conventional radiography
15%
plaque like and oval in configuration calcification conforming to the size and shape of gallbladder
porcelain gallbladder
suspension of radiopaque crystals within the gallbladder bile
milk of calcium bile
how many percent of urinary calculi are present on conventional radiographs
85%
renal calculi are differentiated from gallstones on radiographs by
oblique projections that confirm their posterior position, as opposed to the more anterior positions of gallstones
ureteral calculi are common in what areas of narrowing
ureteropelvic junction, pelvic brim, and vesicoureteral junction
this finding is indicative of chronic obstruction of the cystic duct, chronic gallbladder inflammation and an increased risk of gallbladder carcinoma
porcelain gallbladder
concretions within the lumen of the bowel
appendicolitjs and enteroliths
enteroliths are most common in the colon and often due to calcium deposition on an undigestible material such as
bone, fruit pit, seed, birdshot, medications containing iron and other heavy metals
results from inflammation believed to be due to torsion of the colonic appendages, resulting in vacular occlussion and ischemia. the resultant fat necrosis often calcified resulting in a mobile-shaped calcification
Epiploic appendagitis
staghorn calculi is usually composed of
struvite
calcified adrenal glands are associated with
adrenal hemorrhage in the newborn, TB and Addison disease
pancreatic calcification is associated with
chronic alcohol-induced pancreatitis and hereditary pancreatitis
cyts that commonly calcify and may be found in any intra-abdominal organ as well as within the peritoneal cavity
echinococcus cysts
popcorn calcifications are seen in
uterine leiomyomas
calcified peritoneal metastases are seen in
ovarian or colon mucinous cystadenocarcinoma
renal cell carcinoma calcified in up to how many percent of cases
25%
soft tissue calcifications may be seen in what conditions
hypercalcimic states, idiopathic calcinosis and old hematomas
calcified injection granuloma are commonly from
quinine, bismuth, and calcium salts of penicillin
characteristic “rice-grain” calcifications in muscles
cysticercosis
peritoneal calcifications commonly seen from
peritoneal dialysis, previous peritonitis, or peritoneal carcinomatosis
acute abdomen series include
erect PA chest radiograph, supine and erect or decuitus radiograph of abdomen
air-fluid levels are seen in normal patients commonly in the
stomach, often in small bowel
normal air-fluid levels in small bowel should not exceed __ cm in width
2.5 cm
air-fluid levels should never be see in
colon distal to the hepatic flexure
a normal intestinal gas pattern varies from
no intestinal gas to gas within 3 to 4 variably shaped small intestinal loops measuring less than 2.5 to 3 cm in diameter. normal colon contains some gas and fecal materia and varies in diameter from 3 to 8 cm, with cecum having the largest diameter
drugs that may cause ileus
atropine, glucagon, morphine, barbiturates, phenothiazines
metabolic causes of ileus
DM, hypothyroidism, hypokalemia and hypercalcemia
inflammatory causes of ileus
intraluminal: gastroenteritis; extraluminal: peritonitis, pancreatitis, appendicitis, cholecystitis, abscess
postoperative ileus usually resolves in how many days
4 to 7 days
means stasis and does not differentiate mechanical obstruction from nonmechanical stasis
adynamic ileus
demonstrates diffuse symmetric, predominantly gaseous, distention of bowel. the small bowel, stomach, and colon are proportionally dilated without an abrupt transition
adynamic ileus
true or false: more bowel are dilated in ileus than in obstruction
true
refers to a segment of intestine that becomes paralyzed and dilated as it lies next to an inflamed intra-abdominal organ
sentinel loop
a sentinel loop in the RUQ suggests
acute cholecystitis hepatitis or pyelonephritis
a sentinel loop in LUQ suggests
pancreatitis, pyelonephritis, splenic injury
sentinel loop in the lower quadrant suggests
diverticulitis, appendicitis, salpingitis, cystitis, Crohn disease
75% cases of toxic megacolon is from
ulcerative colitis
a manifestation of fulminant colitis characterized by extreme dialation of all or portion of the colon. peristalsis is absent and large bowel loses all tone and contractility. patient has progressive abdominal distention and is toxic, febrile and obtunded
toxic megacolon
bowel wall becomes “wet blotting paper” and rthe risk of perforation is extreme in this condition
toxic megacolon
most striking finding in toxic megacolon
dilation of transverse colon up to 15 cm in diameter
appearance of colonic walls in toxic megacolon
pseudopolyps are present due to islands of edematous mucosa surrounded by extensive ulceration
stasis of bowel contents above a focal lesion.
mechanical bowel obstruction
mechanical obstruction causes
obturation (occlusion by a mass in the lumen), stenosis due to intrinsic bowel disease, or compression of the lumen by extrinsic disease
refers to blockage of the luminal contents without interference of blood supply
simple obstruction
means that the blood supply to the bowel wall is impaired
strangulation obstruction
most strangulation obstructions are ______, which mean blockage of a bowel loops segment at both ends
closed-loop obstructions
closed-loop obstructions occurs with
incarcerated hernias and volvulus
term applied to necrotizing fasciitis of the perineum, perianal and genital refions
Fournier gangrene
small bowel obstruction is about how many percent of total intestinal obstruction
80%
80% of small bowel obstruction are caused by
incarcerated hernia
strong evidence of obstruction
air-fluid levels at differing heights (>5mm) within the same loop (“dynamic air-fluid levels”)
strong CT evidence of bowel obstruction
small bowel feces
abrupt beak-like narrowing of small bowel, without other lesion evident is indicative of
adhesions as the cause of obstruction
CT findings of strangulation obstruction
circumferential wall thickening, edema of bowel wall (target or halo appearance of lucency in bowel wall), lack of enhancement of bowel wall, haziness or obliteration of the mesenteric vessels, infiltration of the mesentery with fluid or hemorrhage
most specific sign of strangulation obstruction
lack of bowel wall enhancement
small bowel volvulus and closed loop obstruction are indicated by these signs on CT
radial distribution of dilated small bowel with mesenteric vesels converging toward a focus of torsion, U- or C- shaped dilated small bowel loop, “beak” sign at the site of torsion seen as fusiform tapering of a dilated bowel loop, “whirl” sign of tightly twisted mesentery
presence of whirl sign in a patient with SBO correlates strongly with
need for surgery
major cause of SBO in children
intussusception
in adults, intussusception is often chronic, intermittent, or subacute, and is usually caused by a
polypoid tumor such as lipoma
enteroenteric intussusception occurs with
small bowel tumors and sprue
ileocolic intussusception is common in
children
colocolic intussusception is common in
adults
appearance of intussusception in barium studies
coiled spring appearance
appearance of intussusception in CT
target-like intestinal mass
appearance of intussusception in US
donut configuration of alternating hyperechoic and hypoechoic rings representing alternating mucosa, muscular wall and mesenteric fat tissues in cross-section
cause of mechanical small bowel obstruction that should be suspected in any elderly female with SBO. It is the cayse of 24% of SBO in patients over age 70
gallstone ileus
in gallstone ileus, bowel obstruction is caused by a large gallstone that erodes through the gallbladder wall and passes into the intestine, creating a
cholecystoduodenal fistula
gallstone most commonly lodges in what part of the intestine
ileum
Rigler triad of gallstone ileus include
dilated small bowel loops (80%), air in the biliary tree and GB (67%), calcified gallstone in an ectopic location (50%)
there is high risk for perforation with attendant risks of peritonitis and septic shock if cecum exceeds diameter of
10 cm
most colonic obstructions occur in ____ where the bowel lumen is narrower and stool is more formed
sigmoid colon
air-fluid levels in this level are strong evidence of osbtruction, unless the patient has had enema
hepatic flexure
causes of pseudo-obstruction of large bowel
Ogilvie syndrome, adynamic ileus, toxic megacolon
sigmoid volvulus are most common in
elderly and individuals on high residue diets
northern exposure sign is seen in
sigmoid volvulus; wherein the apex of the distended sigmoid colon may extend cephalad to the transverse colon
cecal volvulus occurs most commonly in what age group
30 to 60 age group
most common type of cecal volvulus
twist and invert with the cecum displaced to the LUQ
refers to a folding of the cecum to a position anteromedial to the ascending colon, rather like folding the toe of a sock back on itself
cecal bascule
type of cecal volvulus that results in the cecum remaining in the RLQ
axial twist of cecum
3 types of cecal volvulus
twist and invert with the cecum displaced to LUQ, axial twist of cecum in which cecum remains in the RLQ, cecal bascule
classic radiographic findings in cecal volvulus
coffee bean-shaped loop of gas-distended bowel having haustral markings directed toward the left upper quadrant, apex of cecum in LUQ, cecal distention greater than 10 cm, collapse of distal colon
CT findings of cecal volvulus include
cecum in upper mid and left abdomen, volvulus in RLQ seen as an area of swirling of the bowel and mesenteric fat (“whirl sign”), appendix is displaced to the LUQ, two transition points are present, one for the entering loop and one for the exiting loop, when the loops are completely wound around each other an “x-mark the spot” sign is present formed by the crossing configuration of the transition zones, cecum is distended >10 cm, distal large bowel is decompressed
most specific sign of strangulation obstruction
lack of bowel wall enhancement
most common cause of LBO in elderly and bedridden patients
fecal impaction
rare inflammation of the wall of the colon caused by fecal impaction
stercoral colitis
clinical disorder of acute colonic distention with abdominal pain and distention but withou the presence of mechanical obstruction
colonic pseudo-obstruction (Ogilvie syndrome)
most current theories in Ogilvie syndrome favor what etiology
imbalance in autonomic innervation of the colon
Ogilvie syndrome shows dilatation of the colon most commonly in the
cecum to splenic flexure, occassionaly to the rectum
findings of bowel ischemia include
circumferential or nodular thickening (> 5mm) of bowel wall with infiltration of low density edema or high-density blood resulting from mucosal injury, “thumbprinting resulting from this nodular infiltration of the bowel wall, dilatation of the bowel lumen pneumatosis intestinalis, edema or hemorrhage into the mesentery, engorged mesenteric vessels, thrombosis of mesenteric arteries or veins, poor enhancement of the bowel wall along its mesenteric border which is evidence of ischemia, poor or absent mucosal enhancement with thinning of bowel wall, ascites
refers to gas within the bowel wall
pneumatosis intestinalis
causes of pneumatosis intestinalis
bowel necrosis, mucosal disruption, increased mucosal permeability related to immunosuppresion, pulmonary disease resulting in alveolar disruption and dissection of air along intersitital pathways to the bowel wall
appears on radiographs as cystic air bubble (few mm to several cm) or linear streaks of air within the bowel wall, especially in its most gravity-dependent aspect
pneumatosis intestinalis
a focal collection of clotted blood (>60 HU) that may be seen in the peritoneal cavity adjacent to an injured organ is called
sentinel clot
attenuation value of hemoperitoneum
30-45HU
active bleeding evidenced by extravasated contrast seen during arterial phase of scanning has attenuation value of
85 to 370 HU
maximum dimension of retrocrural LN
6 mm
may enlarged from disease above of below the diaphragm
retrocrural LN
maximum dimension of retroperitoneal LN
10 mm
maximum dimension of gastrohepatic ligament LN
8 mm
maximum dimension of porta hepatis LN
6 mm
maximum dimension of celiac and SMA LN aka preaortic LN
10 mm
maximum dimension of pancreaticoduodenal LN
10 mm
commonly involved LN in lymphoma and GI carcinoma
pancreaticoduodenal
maximum dimension of perisplenic LN
10 mm
maximum dimension of mesenteric LN
10 mm
maximum dimension of pelvic LN
15 mm
abdomen and pelvis contain about how many LNs
more than 230 LNs
morphologic patterns of pathologic lymphadenopathy
single enlarged nodes, multiple separate lobulated enlarged nodes or bulky conglomerate masses of LNs
calcifications in enlarged nodes may be seen with
inflammatory adenopathy, mucinous carcinomas, sarcomas and treated lymphoma
normal lymph nodes appear
oblong in shape, homogeneous in configuration, have short-axis diameters below the limits
low density nodal metastases are commonly seen with
nonseminomatous testicular carcinoma, tuberculosis, and occassionally lymphoma
refers to entrapment of mesenteric vessels by masses of enlarged LNs in the mesentery
sandwich sign
age distribution of Hodgkin lymphoma
bimodal, 25 to 30 and over 50 years
Reed-sterndberg cell is seen in
Hodgkin lymphoma
abdominal adenopathy is seen in how many percent of Hodgkin lymphoma
25%
spleen is involved in how many percent of Hodgkin lymphoma
40%
responsible for 60- 80% of lymphoma
Non hodgkin lymphoma
type of lymphoma that is more common in immunocompromised patients
non hodgkin
type of lymphoma that commonly involve extranodal sites
non hodgkin
solid organ involvement in Hodgkin lymphoma include
spleen, liver, pancreas, kidneys, adrenal glands and testes
abdominal adenopathy is present in how many percent of non hodgkin lymphoma
50%
spectrum of lymphoid hyperplasia and neoplasias in patients who have received solid organ transplants and immunosuppressive therapy
posttransplantation lymphoproliferative disorder
posttransplantation lymphoproliferative disorder results from
Epstein-Barr virus induced proliferatio of B lymphocytes that is usually opposed by functioning T cells
uncommon primary tumor of peritoneal membrane
peritoneal mesothelioma
peritoneal mesothelioma’s prognosis is poor although has improved with
cytoreductive surgery and hyperthermic intraperitoneal chemotherapy
peritoneal metastases are commonly associated with
ovarian, colon, stomach or pancreatic carcinoma
preferential sites for tumor implantation include
pelvic cul-de-sac, right paracolic gutter, and greater omentum
most obvious manifestation of extramedullary hematopoiesis
homogeneous, well-marginated, bilateral paraspinal masses that favor the thoracic spine
benign cystic lesions that arise from lympbtic vascular channels. the cystic mass containes septations and multiple loculations containing chylous, serous, hemorrhagic or mixed fluid
lymphangiomas
most common sarcoma of retroperitoneum
liposarcomas
lymphangiomas occur in
omentum, mesentery, mesocolon, retroperitoneum
rare condition manifest by formation of a fibrous plaque in the lower retroperitoneum that encases and compresses the aorta, IVC and ureters
retroperitoneal fibrosis
drug that is a cause of 12% of cases of retroperitoneal fibrosis
methysergide
5 to 10% of cases of retroperitoneal fibrosis is from
perianeurysmal fibrosis, small foci of metastatic malignancy
hallmark of retroperitoneal fibrosis
smooth extrinsic narrowing of one or both ureters in the region of L4-5
can wooden foreign bodies be seen in conventional radiographs
no
wooden objects in CT appears
high density
retained surgical sponges are called
gossypiboma
most common site for abscess formation
pelvis
most specific sign of abscess
focal collection of extraluminal gas
hernias that are non reducible
incarcerated hernias
refers to hernias associated with bowel obstruction and bowel ischemia
strangulated hernias
hernias that are entrap only to a portion of the bowel wall without compromising viability
Richter hernias
most common hernia in both children and adults
inguinal hernias
hernias that extend through the internal inguinal ring into the inguinal canal lateral to the inferior epigastric vessels
indirect inguinal hernias
hernias that occur medial to the inferior epigastric vessels directly into the inguinal canal through a weakness in its floor
direct inguinal hernias
hernias that are from complications of surgery with herniation through the surgical incision
incisional hernias
hernias that occur in association with surgically created stomas
parastomal hernias
hernias that occur through defects in the lumbar musculature posterolaterally below the 12th rib and above the iliac crest
lumbar hernias
hernias that occur in the lower abdominal wall lateral to the rectus abdominis and inferior to the umbilicus through a defect in the aponeurosis of the transversus abdominis and internal oblique muscles
spigelian hernias
