Peritoneum and retroperitoneum

Question 1

In a study by Snipes 2023 in JAVMA, what were 3 risk factors for the presence of pre-operative AKI in dogs with septic peritonitis? Was AKI a risk factor for survival?

Answer 1

Decreased blood pressure, increased respiratory rate, increased BCS.

Yes. AKI decreased the odds of survival. 21% of dogs did not survive to discharge (75% of these being dogs with AKI).

Question 2

In a study by Sevy 2024 in JAVMA, what was the agreement between findings at exploratory laparotomy and abdominal CT scan?

Answer 2

97%

Question 3

What is the diagnosis based on the following image from Hennessey 2022 in VRU? What was the suspected underlying cause?

Answer 3

Abscess of the hypaxial musculature characterized by well-defined fluid attenuating noncontrast enhancing areas with a contrast enhancing rim.

Migrating foreign body was suspected. Other common CT findings were periosteal reaction and lysis of vertebrae, and retroperitoneal effusion.

Question 4

In a study by Parry 2023 in JVECC, was abdominal CT scan a reliable indicator of malignancy versus benignancy for cases of non-traumatic hemoabdomen?

Answer 4

No - benign v. malignant neoplasms were not accurately identified.

Question 5

In a study by Anderson 2019 in Vet Surg, which of the following laparoscopic abdominal entry techniques was associated with the lowest rate of complications?
1) Veress needle
2) Modified Hasson
3) Ternamian

Answer 5

Ternamian method (cannula entry under endoscope guidance) was associated with the lowest number of complications (9%, compared to 26% [or 5 x risk] for Hasson, and 60% [or 28 x risk] for Veress).

Complications were 12 times more likely in paramedian rather than midline entry.

Question 6

What is the clinical significance of paired slit like openings dorsal to the diaphragm and ventral to the psoas muscles covered by only a thin layer of fascia?

Answer 6

Potentially allow direct extension of disease processes between the thorax and abdomen. Allow for passage of the sympathetic trunk and splanchnic nerves.

Question 7

What is the Cullen sign?

Answer 7

A characteristic ring of subcutaneous hemorrhage around the umbilicus in cases of hemoperitoneum or peritonitis.

Question 8

What are different portions of the omentum?

Answer 8

Greater omentum, comprised of three portions:
1) Bursal - creates the omental bursa.
2) Splenic - gastrosplenic ligament
3) Veil - contains the left limb of the pancreas.

Lesser omentum: gives rise to the hepatoduodenal and hepatogastric ligaments.

Question 9

What organs are considered retroperitoneal?

Answer 9

Kidneys, ureters, adrenal glands, aorta, caudal vena cava, lumbar lymph nodes.

Question 10

What are the peritoneal stomata?

Answer 10

Fenestrations in the basement membrane of the visceral surface of the diaphragm. Important in the clearance of fluid and particles from the peritoneal cavity.

Question 11

What is the predominant cell type of the peritoneal fluid?

Answer 11

Macrophages. Peritoneal fluid is a dialysate of plasma. Normal peritoneal fluid has <3 g/L of protein.

Question 12

What is the primary route of lymphatic drainage from the peritoneum?

Answer 12

Through the diaphragmatic lymphatics to the mediastinal lymph nodes and then into the systemic circulation (via the thoracic duct). This allows for rapid bacteremia in instances of bacterial peritonitis (rapid clearance of particles <10 um in diameter).

Question 13

Which side of the diaphragm has a greater concentration of lymphatics?

Answer 13

Right

Question 14

Aside from particle size, what other factors can affect particulate matter clearance?

Answer 14

Gravity, respiratory movements, diaphragmatic movement, intestinal activity, intraperitoneal pressure.

Question 15

What is the normal intraabdominal pressure in a dog?

Answer 15

2 - 7.5 cm H2O

Question 16

What organ systems are affected by abdominal compartment syndrome?

Answer 16

Acute pulmonary failure secondary to atelectasis, increased pleural and pericardial pressures and decreased venous return, acute renal failure with marked oliguria, intestinal ischemia and bacterial translocation, hepatic ischemia, increased ICP.

Question 17

What causes abdominal adhesion formation?

Answer 17

Fibrin is exuded in response to surgical manipulation or disease. This is normally degraded by fibrinolysis within 3-4 days unless concurrent ischemia is present, in which case fibrin is converted to collagen by fibroblasts. This is worsened in instances of serosal dessication, endotoxemia, and intestinal manipulation.

Question 18

What techniques can be used to minimize abdominal adhesion formation?

Answer 18

Prevention of tissue dessication, gentle tissue handling, meticulous hemostasis, precise suturing, complete removal of blood clots and foreign debris, thorough lavage.

Question 19

What are known adjuvants for peritonitis?

Answer 19

Gastric mucin, bile salts, hemoglobin, barium.

Bile results in hemolysis and release of hemoglobin which impairs phagocytosis and lymphatic drainage. May also provide iron required by bacteria for survival.

Question 20

What are the systemic manifestations of peritonitis?

Answer 20

Hypovolemia and hypoproteinemia (from third spacing of fluid into the abdomen and bowel secondary to reflex ileus), respiratory acidosis and hypoxemia due to diaphragmatic rigidity and increased intraabdominal pressure (which also exacerbates hypovolemia), acute renal failure, release of myocardial depressant factors from the hypoxic pancreas and cardiovascular alterations. Changes to bile flow causes hepatic enzymopathy and icterus. All these changes can be further exacerbated by sepsis or endotoxemia.

Question 21

What is the mortality rate in dogs with MODS secondary to peritonitis?

Answer 21

70% (compared to 25% without). DIC can lead to MODS due to formation of microthrombi.

Question 22

What are the functions of the omentum?

Answer 22

Rich blood supply, high absorptive capacity, pronounced angiogenic activity. Also helps to isolate contamination through formation of adhesions.

Question 23

How does peritonitis result in GI ileus?

Answer 23

Sympathoadrenergic reflex inhibition. Ileus helps to decrease the spread of contaminants but can result in bacterial translocation.

Question 24

What are the classifications of peritonitis?

Answer 24

Primary or secondary, can be further classified into septic or aseptic.

Primary: no obvious source (i.e. FIP), normally monobacterial.
Secondary: most common form in dogs, normally secondary to loss of integrity of the GI or direct innoculation.

Question 25

Describe the pathophysiology of peritonitis in small animals.

Answer 25

Question 26

What are some causes of secondary peritonitis?

Answer 26

Question 27

What is the cause of starch granulomatous peritonitis? What is the treatment?

Answer 27

Suspected hypersensitivity reaction to starch or corn (talcum power no longer used in gloves as could cause significant peritonitis). Treatment is with corticosteroids.

Question 28

What are common causes of chemical peritonitis?

Answer 28

Bile, urine, gastric fluid, pancreatic enzymes. Bile and urine tend to be minimally inflammatory unless concurrent bacterial infection. Pancreatic fluid is intensely inflammatory.

Question 29

What is sclerosing encapsulating peritonitis?

Answer 29

A chronic form of peritonitis where the organs become encased in thick layers of collagenous tissue. Surgical exploration and biopsy from multiple sites is recommended. Corticosteroid therapy may help to slow progression.

Question 30

In dogs undergoing GI surgery what were risk factors for development of septic peritonitis (4)?

Answer 30

H - intraoperative hypotension A - hypoalbuminemia P - hypoproteinemia S - preoperative septic peritonitis Presence of a foreign body is variably a risk factor or protective.

Question 31

In what percentage of septic peritonitis is concurrent pancreatitis observed?

Answer 31

50%

Question 32

What is the most common cause of septic peritonitis?

Answer 32

Leakage from the GI tract

Question 33

What factor drastically affects survival in patients with bile peritonitis?

Answer 33

Concurrent infection (survival of 27% with septic bile peritonitis in one study, compared to 100% when sterile).

Question 34

Are upper or lower GI perforations associated with a higher mortality rate?

Answer 34

Lower GI due to higher bacterial load and greater proportion of anaerobic bacteria.

Question 35

What two bacterial species predominate in cases of septic peritonitis caused by bowel perforation?

Answer 35

E. coli and Bacteroides fragilis. E.coli causes early mortality due to release of endotoxins (specifically alpha hemolysin), B.fragilis enhances the lethality of E.coli.

Question 36

What volume of peritoneal fluid can be detected on abdominal ballottement?

Answer 36

10 ml/kg

Question 37

What are the physical examination parameters of SIRS for dogs?

Answer 37

Question 38

What are the physical examination parameters of SIRS for cats?

Answer 38

Question 39

What are some common radiographic signs of peritonitis?

Answer 39

Loss of serosal detail, ground glass appearance (with large volumes of fluid only), free peritoneal gas.

Question 40

How much higher is the mortality in cases of bicavitary effusion?

Answer 40

3 times increased risk of mortality. Most often caused by infectious agents or pancreatitis.

Question 41

What are some common ultrasonographic signs of peritonitis?

Answer 41

Corrugation of the small intestines, fluid, gas. Note: 20% of dogs had residual air or fluid in the peritoneum 10 days following uncomplicated GI surgery in one study.

Question 42

In what percentage of dogs are single abdominal paracentesis results positive with 3ml/kg of fluid?

Answer 42

20%. This increases to 80% for 10 ml/kg of fluid

Question 43

Which of the following techniques has the highest diagnostic accuracy for detection of peritonitis? 1) Needle paracentesis 2) Catheter paracentesis 3) Diagnostic peritoneal lavage

Answer 43

Needle: 43% Catheter: 83% Peritoneal lavage: 95%

Question 44

How is diagnostic peritoneal lavage performed?

Answer 44

20 - 22 ml/kg of saline is instilled into the abdomen, the animal is rolled for 10 minutes and a large aliquot of fluid is recovered.

Question 45

Describe the parameters for diagnosis of septic inflammation, uroperitoneum, and chyloperitoneum based on abdominocentesis.

Answer 45

Question 46

What findings on cytologic examination of peritoneal fluid warrant surgical exploration?

Answer 46

Toxic and degenerate neutrophils, bacteria or plant material.

Question 47

What level of peritoneal fluid bilirubin is indicative of free intraperitoneal bile?

Answer 47

2 x the serum bilirubin concentration. May see a green granular pigment cytologically or basophilic mucinous material.

Question 48

What do peritoneal lipase and amylase concentrations in excess of serum concentrations indicate?

Answer 48

Intestinal ischemic injury and pancreatic injury or inflammation.

Question 49

How does anemia affect blood glucose on point-of-care glucometer?

Answer 49

Will falsely increase blood glucose. Care when interpreting results for diagnosis of septic peritonitis.

Question 50

What blood-to-fluid lactate difference is indicative of septic peritonitis?

Answer 50

- 2mmol/L (or a total peritoneal lactate >2.5 mmol/L also suggests sepsis). These indicators are not reliable in cats.

Question 51

How accurate is cytology in the diagnosis of septic peritonitis?

Answer 51

87%

Question 52

What are the goals of fluid resuscitation for CVP and urine output in patients with septic peritonitis?

Answer 52

CVP of 0-5 cmH2O Urine output of 1-2 ml/kg/hr

Question 53

What antimicrobial drugs are recommended for empiric antimicrobial selection in patients with septic peritonitis?

Answer 53

Ideally drugs effective against both gram positive and gram negative aerobes and anaerobes. Typically a third generation cephalosporin or ampicillin and an aminoglycoside are recommended. In one retrospective study only 28% of gram positive organisms and 52% of gram negative organisms were sensitive to fluoroquinolones.

Question 54

What are the goals of surgical treatment of patients with septic peritonitis?

Answer 54

Elimination or correction of the source of contamination/infection, reduction of the bacterial load, removal of foreign material and inflammatory cells, prevention of persistent or recurrent infection.

Question 55

What volume of fluid is recommended for pertioneal lavage?

Answer 55

200 - 300 ml/kg, or until the fluid is clear. Efficacy of lavage for improving clinical outcomes remains uncertain.

Question 56

What are some surgical methods proposed to help decrease the risk of enterotomy or anastomotic leakage in patients undergoing correction of septic peritonitis?

Answer 56

Serosal patching, fibrin sealant, omentalization.

Question 57

Why is laparoscopic surgery potentially detrimental in patients with septic peritonitis?

Answer 57

Diffuse damage to the peritoneum occurs secondary to insufflation.

Question 58

What are the proposed advantages and disadvantages of open peritoneal drainage?

Answer 58

Advantages: increased efficiency of removal of bacteria (may also prevent proliferation of anaerobic bacteria), foreign material and inflammatory mediators. Disadvantages: nosocomial infection, hypoalbuminemia, hypoproteinemia, anemia. In humans it is associated with worsening organ dysfunction, amplified inflammation, and greater use of blood component therapy. Can also be performed using negative pressure wound therapy (vacuum assisted closure).

Question 59

What are some reported indications for open peritoneal drainage?

Answer 59

Severe systemic manifestations of peritonitis, ineffective drainage with conventional procedures, and extensive suppuration or necrosis of the deep layers of the incision.

Question 60

What factors are used to determine closure of open peritoneal drainage?

Answer 60

Appearance of the wound and peritoneal effusion, cytology.

Question 61

What are the most common complications associated with the use of closed suction abdominal drainage?

Answer 61

Hypoproteinemia, anemia, edema. All occurred in around 50% of cases.

Question 62

Why are epidurals contraindicated in patients with septic peritonitis?

Answer 62

May decrease survival times and decreased cardiac and renal function attributed to abdominal sympathetic blockade.

Question 63

Is canine or human specific albumin preferred for supplementation in dogs, if required?

Answer 63

Canine. There is a high rate of type III hypersensitivity reactions to human albumin, and significant morbidity and mortality.

Question 64

What are reported survival rates for dogs with septic peritonitis?

Answer 64

Varied. Range from 50-80% for open peritoneal drainage, closed suction drainage, and primary closure.

Question 65

What are negative prognostic indicators for survival in septic peritonitis?

Answer 65

Hypotension, CV collapse, respiratory distress, DIC, pre-operative ALT and GGT, plasma lactate >2.5 mmol/L on admission, inability to normalize lactate within 6 hours, preoperative protein C above 60%, antithrombin activity above 42%, ionized hypocalcemia, MODS.

Question 66

What are indications for surgical exploration of bite wounds to the abdomen?

Answer 66

Persistent hemorrhage, positive diagnostic peritoneal lavage or abdominocentesis, abscessation or necrosis, herniation.

Question 67

What is the major pathogen in dog and cat bite wounds?

Answer 67

Pasteurella multocida. Staphylococcus and clostridium were most common in gunshot wounds.

Question 68

Is urine a adjuvant compound in peritonitis?

Answer 68

No, chemical peritonitis is normally minimal.

Question 69

Are peritoneal urea concentrations useful in the diagnosis of uroabdomen?

Answer 69

No, they re-equilibriate quickly with the serum.

Question 70

What is the most common cause of chyloperitoneum?

Answer 70

Neoplastic disease

Question 71

What is the most common anaerobic organism implicated in abdominal abscess formation?

Answer 71

B.fragilis

Question 72

What are the most common sources of bleeding in cases of traumatic hemoabdomen?

Answer 72

Spleen, liver and kidneys.

Question 73

What is the most common primary retroperitoneal neoplasia in small animals?

Answer 73

Lipoma

Question 74

What is the most common cause of retroperitonitis?

Answer 74

Foreign body migration or ovarian pedicle granuloma after hysterectomy.

Question 75

What is the difference between a fistula and a sinus tract?

Answer 75

A fistula is between two epithelial surfaces. Because the mesothelium is distinct from epithelium, draining tracts from the peritoneum to the skin surface are termed sinus tracts.

Question 76

What are some imaging techniques that may be useful in the investigation of sinus tracts?

Answer 76

Radiography +/- positive contrast sinography, ultrasonography, CT, MRI. Most frequently secondary to migrating foreign bodies, often occur in the sublumbar region and are thought to migrate from the respiratory tract following inhalation.

Question 77

Exposure to what substance is thought to result in mesothelioma in dogs?

Answer 77

Asbestos (75% of dogs diagnosed with mesothelioma in one study had exposure).

Question 78

How is mesothelioma diagnosed?

Answer 78

Generally requires histopathology, as it is not uncommon to see reactive mesothelial cells in effusions of various causes. Immunohistochemistry may be required.

Question 79

What is the MST for mesothelioma?

Answer 79

60 days (although longer survival has been reported in some cases - 42 months in one case with repeated abdominal drainage).