Define Stoma according to Harrison book of internal medicine
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Here is what Harrison's Principles of Internal Medicine (22nd Edition, 2025) says about "stoma":
Definition of Stoma - Harrison's Principles of Internal Medicine, 22E
Harrison's uses the term "stoma" in two distinct contexts:
1. Stoma in Hematology (Red Cell Morphology)
Defined in Chapter 65 - Interpreting Peripheral Blood Smears (Figure 65-15):
"Red cells characterized by a wide transverse slit or stoma."
This is the defining morphological feature of stomatocytes - red blood cells that display a slit- or mouth-like pale area across the center of the cell (the word "stoma" comes from Greek for "mouth"). The figure caption further explains:
- This appearance is often seen as an artifact in a dehydrated blood smear.
- Stomatocytes can be seen in hemolytic anemias and in conditions where the red cell is overhydrated or dehydrated.
Below is the actual microscopy image from Harrison's (Figure 65-15) showing stomatocytosis:
FIGURE 65-15 Stomatocytosis. Red cells characterized by a wide transverse slit or stoma.
2. Stoma in Surgery / Urology (Surgical Opening)
In the context of bladder cancer management (Chapter 91 - Treatment Approaches), Harrison's describes a stoma as:
An opening brought through an incision in the abdominal wall that drains body fluid (urine or intestinal contents) into an affixed bag outside of the body.
Specifically, in an ileostomy (urinary diversion after cystectomy):
"...the bilateral ureters are connected to a portion of ileum that is brought through an incision in the abdominal wall to create a stoma that drains urine into an affixed bag outside of the body."
A stoma tract is also referenced in the context of a continent urinary reservoir ("Indiana pouch"), where patients catheterize the reservoir several times per day via a small stoma tract.
Summary
| Context | Harrison's Definition of Stoma |
|---|---|
| Hematology | A wide transverse slit on a red blood cell, giving it a mouth-like appearance (stomatocyte) |
| Surgery/Urology | An artificially created opening in the abdominal wall connecting an internal organ (bowel or ureter) to the outside of the body |
- Harrison's Principles of Internal Medicine, 22E, Chapter 65 (Peripheral Blood Smears), Figure 65-15
- Harrison's Principles of Internal Medicine, 22E, Chapter 91 (Bladder Cancer Treatment)
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