Ch. 86 Peritoneum Flashcards
What mesoderm gives rise to the peritoneal cavity?
the somatic (parietal) and the splanchnic (visceral) mesoderms
What is the coelom?
this is the space that is enclosed by the somatic and splanchnic mesoderm - party will be enclosed as the body cavity and the rest is transient but in the embryo, it is all continuous
what is an omphalocele
embryonic herniation of abdominal contents through the umbilicus into the umbilical stalk
an umbilical hernia results from a defect in development of the muscular wall around the umbilicus
What are the nine regions of the abdominal cavity and how is it divided?
Divided by two transverse and two sagittal planes
right and left hypochondriac regions, epigastric or xiphoid region, umbilical region, left and right lateral regions (includes flanks and paralumbar fossae), right and left inguinal regions, and pubic region
Where do the sympathetic and splanchnic nerves enter the abdominal cavity?
through paired slit like openings dorsal to the diaphragm and ventral to the psoas muscles
What passes through the inguinal canal
vaginal process with the spermatic cord or round ligament in the female
external pudendal vessels
genital nerve
What passes through the vascular lacunae?
in the caudal abdomen, the vascular lacunae contains the femoral artery and vein, lymphatics, and saphenous nerve
what is a cullen sign
a ring of subcutaneous hemorrhage around the umbilicus may appear in cases of a hemoperitoneum or septic abdomen if there is a direct extension from the abdominal cavity into the subcutis - this would be from an incomplete mesodermal lining at the level of the umbilicus
what is the peritoneal cavity?
a potential space between the visceral and parietal peritoneum and contans no organs except at the time of ovulation when the egg ruptures from the ovary
what are the three portions of greater omentum?
bursal, splenic, veil
what is the bursal portion of the greater omentum
the omental bursa is a potential space between the paries superficiales and paries profundus layers
opens at the epiploic foramen when is bounded dorsally by the caudal vena cava and ventrally by the portal vein
The bursal portion is what is used for omentalization
what are the boundaries of the epiploic foramen
dorsally: caudal vena cava
ventrally: portal vein
what is the splenic portion of the greater omentum
extends to the hilus of the spleen to form the gastrosplenic ligament
what is the veil portion of the greater omentum
the smallest portion of the greater omentum
contains the left limb of the pancreas
what are the boundaries of the lesser omentum
lies between the lesser curvature of the stomach and porta hepatis and becomes continuous with the mesoduodenum
some of the lesser omentum will give rise to the hepatoduodenal ligament and the hepatogastric ligament
what are milky spots?
aggregations of cells within the omentum which contain neutrophils, macrophages, and lymphocytes
Describe the peritoneum on a microscopic level
a single layer of squamous cells of mesothelial origin
covered in microvilli
the squamous cells are supported by connective tissue layer
the peritoneum on the visceral surface of the diaphragm has fenestrations, or stomata, of varying size - 4-16 um in dogs and cats
The stomata and the lymph vessels (called lacunae) aid in clearance of fluid from the cavity
what is the colloid osmotic pressure of normal peritoneal fluid? what is the normal protein concentration? what is the normal number of cells?
normal colloid osmotic pressure is 28 mmHg
normal protein is 3 g/dL
normal cells <300
what is the protein and cell count for a transudate
protein <2.5 g/dL
cells <1500 cells/uL
what is the protein and cell count in a modified transudate
protein 2.5-7.5 g/dL
cells 1000-7000 cells/uL
what is the protein and cell count for an exudate
protein >3 g/dL
cells >5000 cells/uL
How quickly does the abdominal lymph system drain
The primary route of drainage of particles was through the diaphragmatic lymphatics to the mediastinal lymph node and finally by way of the thoracic duct into the systemic circulation
For small particles less than 10 um, within about 10-90 minutes for a dog and 3 minutes for a cat if injected intraperitoneally
What causes lymph to flow from the peritoneal cavity
Passive stretching of the diaphragm moves fluid from the cavity to the diaphragmatic lacunae. Diaphragmatic muscle contraction and decreased intrathoracic pressure during exhalation moves fluid through the lymphatics into efferent ducts along a pressure gradient
Which side of the body has a higher distribution of lymphatics?
the right side - no idea why
How quickly can the peritoneal cavity absorb fluid
3-8% of body weight per hour
what is the normal range for intrabdominal pressure in a dog
2.0-7.5 cm H20
mean 4.5 cm H20
How do you convert mm Hg to cm H20?
multiple mm Hg by 1.36 to get cm H20
What does altered abdominal compliance result in?
increased intrabdominal pressure
At what pressure, in pigs, will abdominal insufflation cause increased HR, increased MAP, increased systemic vascular resistance, decreased cardiac output, decreased mesenteric arterial blood flow, decreased intestinal mucosal blood flow, increased bacterial translocation?
greater than 20.4 cm H20
what is acute abdominal compartment syndrome
a marked increase in intraabdominal pressure and is associated with MODS because of compressive atelectasis with increased peak inspiratory pressure –> impaired gas exchange, increased pleural and pericardial pressures, decreased venous return, intestinal ischemia, renal failure
how do you diagnose acute abdominal compartment syndrome
high peak inspiratory pressure with oliguria and an apparently tight abdomen
usually the urinary bladder pressure would be greater than 20-25 cm H20
What must the environment be for adhesions to form
inflammatory cells and fibrin come in and in the absence of ischemia, fibrinolysis occurs
if there is vascular damage though, fibrin is infiltrated by fibroblasts making collagen and then fibrinous adhesions form
what is the mainstay of peritoneal fluid’s innate defense system
release of C3a and C5a, which will stimulate neutrophil chemotaxis and degranulation of basophils and mast cells
What cytokines are dominant in a gram negative peritonitis
TNF alpha and IL 6
What happens to the peritoneal fibrinolytic system during inflammation
the system is inactivated
lack of fibrin clearance leads to fibrin clumps
fibrin clumps will occlude peritoneal stomata and impede clearance of fluid and particles
the fibrin then sequesters microorganisms from normal host defenses
how does gastrin mucin polysaccharide act as a peritonitis adjuvant
has a heparin like anticomplement effect that inhibits phagocytosis
how do bile salts act as a peritonitis adjuvant
lowers surface tension and lyses RBCs which release hemoglobin
hemoglobin interferes with phagocytic cell chemotaxis and intracellular killing
may also provide iron to microorganisms
inhibits bacterial clearance from the peritoneal cavity by interfering with lymphatic clearance mechanisms
how does peritonitis cause ileus?
sympathoadrenergic reflex inhibition
the reflexes completely block myenteric cholinergic neurons
what is the role of reflex rigidity in peritonitis
diaphragmatic rigidity impedes respiratory movements which then reduces intraperitoneal circulation and decreases the lymphatic clearance of fluid through the diaphragm
what is primary peritonitis
spontaneous inflammation in the abscence of an evident intraabdominal source of infection or penetrating injury
usually monobacterial and may be called spontaneous bacterial peritonitis
best example would be feline coronavirus causing FIP
what is secondary peritonitis
secondary generalized septic peritonitis is the most common form of peritonitis in dogs
basically, there is a source for the peritonitis that is clearly evident
examples of causes of aseptic peritonitis
chemical (like pancreatitis or barium) bile (usually aseptic) uroperitoneum (usually aseptic) peritoneal FB starch granulomatous peritonitis mechanical peritonitis sclerosing encapsulating peritonitis
examples of causes of septic peritonitis
leakage of GI contents penetrating abdominal wounds blunt abdominal trauma ischemic intestinal injury pancreatitis rupture pyometra uterine torsion ruptured prostatic abscess liver abscess or hepatitis splenic abscess or splenitis splenic torsion msenteric lymph node abscess ruptured gallblader or bile duct with bacterbilia ruptured bladder with cystitis umbilical abscess surgical contamination peritoneal dialysis
how would a gosspiboma appear on ultrasound
likely would have a hypoechoic mass with an irregular hyperechoic center
how can starch induced peritonitis be diagnosed
iodine staining or polarized light microscopic exam of peritoneal fluid
treat with steroids
what is the most common source of septic peritonitis?
intraabdominal bacterial contamination and GI leakage in 60-63% of septic peritonitis cases in dogs and 47% of septic peritonitis cases in cats
