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596 PART 8 ■ Fundamentals of Hematological Analysis
have various appearances; some resemble large plasma cells. visceral and parietal peritonea. T e potential space between
T e nucleus or nuclei have a round to oval appearance and the parietal and visceral layers o the peritoneum is the
occupy about one third to one hal o the cell’s diameter. peritoneal cavity. T e parietal peritoneum lines the entire
Although one to three nucleoli may be seen, cells may be abdominal cavity. At the posterior midline, the le and right
multinucleated. Occasionally, a cell may contain 20 or more sheets o the membrane come together to orm a double
nuclei. T e nuclear contour is usually smooth and regular, membrane, the mesentery. Each o the abdominal organs is
with stippled and dark-purple nuclear chromatin. suspended by this mesentery. As the sheets separate to sur-
T e cytoplasm is abundant and varies rom light gray to round an organ, they become the visceral peritoneum o
deep blue. Localized basophilic areas are o en seen in the the organ. In two places within the abdominal cavity, mes-
center o the cell. T is perinuclear zone o pallor resembles enteries extend beyond the organs and orm a our-layered
a ried egg in appearance. Cytoplasmic vacuoles o various thickness, the omenta. Omenta contain phagocytic cells
sizes are o en seen. Vacuoles or clear areas at the periphery that protect the abdominal cavity rom in ection. However,
o the cytoplasm probably represent glycogen. peritonitis, an inf ammation o these membranes, can result
Degenerative mesothelial cells may show pyknosis and rom in ection or chemical irritation.
karyorrhexis. T ey may also exhibit phagocytosis and trans- A small amount o f uid, ormed by the ultra ltration o
orm into macrophages. iny projections o microvilli may plasma, lubricates the peritoneum. T e presence o this f uid,
be observed extending rom the periphery o the cytoplasm; called peritoneal f uid, reduces riction between the visceral
this is an arti act. and parietal peritonea as they move against each other.
Mesothelial cells are seen in variable numbers in most
e usions and are increased in sterile inf ammations caused Peritoneal Effusion
by such conditions as pleurisy associated with pulmonary An abnormal amount o peritoneal uid (an e usion) can
in arction. Few cells, i any, are seen in e usions rom patients accumulate in the peritoneal cavity i the balance between
with tubercular pleurisy or when an increased number o f uid ormation and reabsorption is altered by a disease pro-
pyogenic organisms are present in the e usion. I the num- cess. T e collection o f uid in the peritoneal cavity, ascites,
ber o large mesothelial cells, di ering rom macrophages, is results rom increased hydrostatic pressure in the systemic
more than 5%, tuberculosis is ruled out. circulation, increased peritoneal capillary permeability,
decreased plasma oncotic pressure, or decreased f uid reab-
Cytological Exam ination sorption by the lymphatic system. T e procedure or remov-
Most malignant e usions are caused by metastatic adenocar- ing f uid rom the peritoneal cavity is paracentesis.
cinoma because o its peripheral location and high incidence.
Analysis o body f uids, secretions, and tissue biopsy speci- Causes of Peritoneal Effusions
mens can be valuable in the diagnosis o carcinoma. Another T e causes o peritoneal e usions range rom disorders and
source or the diagnosis o pleural malignancy is sputum. diseases that directly represent involvement o the perito-
T e presence o a massive bloody (hemorrhagic) e u- neum, such as bacterial peritonitis, to abdominal condi-
sion in the absence o trauma is highly suggestive o malig- tions that do not directly involve the peritoneum, such as
nancy. T e number o malignant cells varies. On microscopic hepatic cirrhosis, cirrhosis, congestive heart ailure, Budd-
examination, tumor cells requently aggregate in clumps and Chiari syndrome, hypoalbuminemia (caused by nephrotic
sometimes show gland-like ormation. Characteristics o syndrome or protein-losing enteropathy malnutrition), and
malignant cells include the ollowing: miscellaneous disorders such as myxedema, ovarian dis-
eases, pancreatic disease, and chylous ascites.
1. Variation in cell sizes and shapes (pleomorphic) or simi- E usions that may con orm with the de nition o transu-
lar in appearance (monomorphic)
2. Multiple, round aggregates o cells dates can be associated with congestive heart ailure, hepatic
cirrhosis, and hypoproteinemia.
3. High nuclear-cytoplasmic (N:C) ratio E usions that may con orm with the de nition o exu-
4. Irregularity in nuclear size and shape dates can be associated with primary or secondary peritoni-
5. Coarseness and clumping o chromatin tis, malignant disorders, trauma, and pancreatitis.
6. Large, prominent, irregular nucleoli
7. Possible giant vacuoles Laboratory Analysis
8. Basophilic or vacuolated (mucin-containing) cytoplasm T e laboratory criteria or distinguishing transudates rom
9. Irregular and abnormal mitosis
10. Engul ment o malignant cells by other malignant cells exudates are less clearly de ned or peritoneal (ascitic) f uid
than or pleural f uid. ransudates are usually clear and pale
Peritoneal Fluid yellow. Exudates are cloudy or turbid because o an increased
concentration o leukocytes, elevated protein levels, and
Anatomy of the Peritoneum occasionally microorganisms. Exudates may be seen in peri-
T e peritoneum is a smooth membrane that covers the tonitis, cases o per orated or in arcted intestine, and pancre-
abdominal walls and viscera o the abdomen and pelvis atitis. An evaluation o ascitic f uid includes gross inspection,
(Fig. 29.6). T e continuous sheet o single-cell layers o total cell count, microscopic examination o sediment or
mesothelial cells supported by connective tissue orms the cell di erentiation, cytological studies, chemical analysis or
