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CYTOLOGICAL EVALUATION OF FETAL MATURITY BY STUDYING THE EFF
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04.05.06 (2 years ago)
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CYTOLOGICAL EVALUATION OF FETAL MATURITY BY STUDYING THE EFFECTS OF HORMONES IN LATERAL VAGINAL WALL SMEAR
Smears are taken from the upper two thirds of the lateral vaginal wall by a wooden or plastic spatula. Immediately a smear is made from this on a clean glass slide. The slide is immersed in 95% ethanol ( without drying it).
Normal vaginal epithelium is lined by a stratified multilayered squamous epithelium. The thickness and structure of the epithelium is closely related to the conc. of the circulating ovarian hormones.
Under the influence of unopposed estrogen ( no opposition by progesterone e.g., in the proliferative phase) due to the absence of progesterone, this vaginal epithelium is fully mature and fully developed and has 4 layers e.g.,
1) The Basal Cell layers( the reserve cell layer): this layer consists of ONE ROW of cells. These are very small cuboidal cells with relatively large nuclei. They are firmly attached to basement membrane and not exfoliated. THIS CELL LAYER DOES NOT EXFOLIATE. The regeneration of vaginal epithelium occurs from the basal cell layer.
2) The Para Basal Cell layer: this layer is composed of several ROWS of cells. They are slightly larger with central nuclei also slightly larger. Para basal cells exfoliate. The exfoliated parabasal cells are squamous, small, round or oval. They stain blue against a clear and clean background of the vaginal smear. Cytoplasm is compact, central nuclei relatively large. Presence of exfoliated parabasal cells in large numbers in vaginal smears means ovarian inactivity( no hormone stimulus e.g., immediately after delivery.)
3) The Intermediate Cell layer: composed of several rows of cells. These are flatter in shape. Nuclei are vesicular. Cells are rich in glycogen content under the influence of larger amounts of progesterone and low amounts of estrogen, this layer is especially well developed and thickened. The presence of large number of intermediate cells against a dirty and messy background of Doderlain bacilli/cell debris/mucus /leucocytes—means progesterone influence as in the 2nd half of ovulatory menstrual cycle (i.e. post ovulatory menstrual cycle). There is a special and particular form of intermediate cell i.e. curled cell form of intermediate sq cell called Navicular cell. Navicular cell is oval (boat) shaped cell originally described by Papanicolaou in 1925. The cell border of this cell is thickened and prominent. Cytoplasm stains light. Nuclei are vesicular and eccentric. If there is subsequent insufficient progesterone production without simultaneous estrogen reduction-the above smear will have-
1-disappearance of navicular clusters
2-breaking up intermediate cell clusters
3-replacement of intermediate cells by superficial squamous cells
Exfoliated intermediate squamous cells are slightly smaller cells. Stain pale blue. Cytoplasm is less transparent and rather denser. Nuclei are vesicular. These cells have a tendency to curl at the edges. These cells are “sticky” in nature and so they adhere to each other and clump together in masses thus forming clusters. They exfoliate also in clusters. Navicular cells when found in vaginal smear are found in clusters. These navicular cells are found-
1-in hormonally normal pregnancy in large numbers
2-in excessive androgen production due to progesterone effect
3-O+P pill
4-low estrogen status( with progesterone)
Navicular clusters are always found whenever there is a marked thickening of the intermediate squamous cell layer of the vaginal epithelium.
4) Superficial Squamous Cell layer: this layer is composed of few rows of cells. These are large flat cells with pyknotic nuclei. The percentage of squamous epithelial cells having this nuclear pyknosis is known as karyopyknotic index (KI). The percentage of superficial squamous cells showing cytoplasmic acidophilia is known as eosinophilic index (EI) or cornification index(CI). Sometimes this layer contains anucleated keratinized cells in the topmost layer. Estrogen is the only hormone that promotes vaginal squamous proliferation to the superficial layer (means progesterone is either low or absent simultaneously). Exfoliated superficial squamous cells are seen as large polyhedral-flat-lying singly. Nuclei are pyknotic, cytoplasm thin, transparent stains pink with Pap staining technique. These are most mature cells of the vaginal epithelium. There presence in the smear means highest degree of vaginal proliferation-unopposed estrogen influence (no or lack of progesterone to oppose estrogen) simultaneously e.g., proliferative / 1st half of normal menst cycle / estrogen administration / estrogen producing tumor / some androgen due to estrogen effect and other conditions associated with excessive estrogen production.
There is no characteristic pattern if there is lack of estrogen while progesterone levels are maintained or if the quantities of both hormones are simultaneously reduced.
PARABASAL CELLS INTERMEDIATE CELLS SUPERFICIAL CELLS
A shift towards this A shift towards this A shift towards this
A shift to left Shift to midzone Is shift to right
A shift towards to right If from right then a midzone shift to left
-then it is midzone shift to the right If from left then a midzone shift to the right
In hormonally normal pregnancy
Due to large amounts of progesterone ( corpus luteum in 1st trimester and placenta later on )
And large amounts of estrogen---- placenta and the fetus.
Vaginal smears are seen as :
1st trimester (corpus luteum phase):
1) progressive enlargement of intermediate cell layers because of progesterone influence of post ovulatory phase.
2) more dense clustering of these intermediate cells
3) marked decrease in superficial cells(present from preovulatory phase of menstrual cycle)
4) E.I. falls below 5% and K.I. not > 10%
Mid pregnancy smear (from 3rd month onwards until 2-3 months prior to term ):
1) large nos of clusters of intermediate cells are formed
2) large nos of thick clusters of navicular cells are formed. Navicular cells appear after 3rd week
3) no superficial cells are formed ( because large amounts of estrogens are opposed by large amounts of progesterone)
4) E.I and K.I are very low --- each < 10%
5) background is dirty and messy as said earlier
At Term Smear (from 38-40 wks—beginning fall of progesterone by placenta):
1) less no of navicular cells
2) small no of individual clusters of navicular cells
3) discrete intermediate squamous cells
4) maturity index slightly shifts to right
5) E.I rises to > 5-6% ( even 10 %)
6) K.I rises to about 15-20 %
----------------means impending delivery
Beyond Term Smear:
1) no intermediate cells
2) no navicular cells
Post Term Smear:
1) no intermediate cells
2) no navicular cells
3) no superficial cells
4) considerable number of parabolas cells appear so there is significant shift of M.I to “left” : 100/0/0---means fetus in danger and deliver the patient immediately.
5) Nearly all cells are single
But these are not always accurate and reliable tests so not used routinely.
Maturation Index (M.I.): it is the expression of percentage of the 3 major types of cells exfoliated from the stratified squamous epithelium of vaginal walls egg.
Parabasal Intermediate Superficial
Squamous Squamous Squamous
Cells Cells Cells
The order is just like above.
Each cell type has been given a Maturation value
Parabasal =0 intermediate =0.5 superficial=5.0
In mid cycle of normal ovulatory menst cycle the M.I =0 / 40 / 60
In 1st half of menstrual cycle M.I=0 / 0 / 100----completely right
At midcycle ( i.e. at ovulation) it is 0 / 40 / 60 ---slight shift to right
---so a shift of M.I to midzone
In 2nd half =0 / 70 / 30 ------shift to left in midzone
In hormonally normal pregnancy =0 / 95 / 5----shift to midzone
Soon after conception---progesterone is secreted by the corpus luteum. So M.I shifts towards the midzone 0 / 70 / 30 it does not go in reverse order i.e. to preovular pattern.
It continues to be there throughout pregnancy 0 / 95 / 5 due to massive levels of O and P and other cortical steroids. It continues it’s midzone shift until usually within a few weeks of delivery i.e. it reaches it’s characteristic pattern of pregnancy i.e. an extreme shift to midzone of M.I to 0 / 95 / 5. This pattern is not reversed towards the preovulatory pattern as in normal menstrual cycle.
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