Vaginal smear cytology

Cytology of vaginal smear

A cytological examination of a vaginal smear is performed to assess ovarian function. Depending on the ratio of cells of different epithelial layers in smears, 4 types of cellular reactions are distinguished, which allow us to judge the functional state of the ovaries.

• Type I. Smears reflecting significant estrogen deficiency consist of basal cells with large nuclei and leukocytes; cells of the overlying layers are absent.
• Type II. With a moderate degree of estrogen deficiency, smears show predominantly parabasal cells with large nuclei; leukocytes are either absent or few in number; basal and intermediate cells may be present.
• Type III. With minor estrogen deficiency, the smear predominantly contains intermediate layer cells with medium-sized nuclei, single superficial cells, and basal layer cells.
• Type IV: With sufficient secretion of estrogens, the smear consists of superficial epithelial cells.

In clinical practice, smears cannot always be strictly classified as one type or another. Sometimes mixed pictures are observed, which are classified as intermediate types. In addition, the type of smear also depends on the phase of the menstrual cycle. In a normal ovarian-menstrual cycle, type III smear is observed in the proliferation phase, and type III or IV during ovulation.

A vaginal smear test to determine the functional state of the ovaries cannot be performed in the presence of inflammatory discharge, after vaginal manipulations, or with intravaginal administration of medications.

For a more accurate assessment of hormonal stimulation using the cytological method, the following indices are used.

• Karyopyknotic index (KPI) is the ratio of superficial cells with pyknotic nuclei (less than 5 µm) to superficial cells with nuclei larger than 6 µm. With a normal vaginal pH reaction, the KPI value (%) strictly depends on the phase of the ovulatory menstrual cycle.

KPI values during the ovulatory menstrual cycle

	Days of the menstrual cycle
	-10-8	-6-4	-2-0	+2-(+4)	+6-(+8)	+10-(+12)
KPI, %	20-40	50-70	80-88	60-40	30-25	25-20

• Atrophic index is the ratio of the number of cells in the deep layers (basal and parabasal) to the total number of cells.
• The intermediate cell index is the ratio of the number of intermediate cells to the total number of cells in the smear.
• Eosinophilic index (acidophilic) - the ratio of superficial acidophilic cells to superficial basophilic cells. The stronger the estrogenic stimulation, the more superficial eosinophilic-stained cells appear in smears.
• Maturation index is a differentiated count of cell populations, expressed as a percentage. When calculating the maturation index, the smear should include only freely separated cells with normal morphology. The higher the degree of epithelial maturation, the more cells with a high maturation index in the smears and the higher the total amount obtained when calculating the cellular composition of the smear.

To derive indices, at least 200 cells are counted. The result is expressed as a percentage. The greatest value is the CPI, the indicators of which more accurately coincide with the level of hormone secretion. During a normal menstrual cycle, the CPI changes as follows: during menstruation up to 80-88%, in the progesterone phase up to 20%; in the luteal phase up to 20-25%, i.e. it is maximum in type IV vaginal smears.

The atrophic index is high (50-100%) in types I and II of vaginal smears; the index of intermediate cells reaches 50-75% in types II and III, and an increase in the eosinophilic index (up to 70%) is observed during ovulation.

Widal's scheme for evaluating a colpocytogram

Type of cellular reactions	Vaginal epithelial index,%
	Atrophic	Intermediate cells	Karyopyknotic
I	100	0	0
I- II	75	25	0
II	50	50	0
II-III	25	75	0
III	0	75	25
III -IV	0	75-50	25-50
IV	0	50-25	50-75

It should be noted that recently the cytological method of assessing ovarian function has been replaced by determining the concentration of sex hormones in the blood.

In addition to assessing the functional state of the ovaries, cytological examination of vaginal smears is important for identifying atypical cells. Signs of the latter include: polymorphism of cells and their nuclei, pronounced anisochromia of the cytoplasm, nuclei, an increase in the nuclear-cytoplasmic index, uneven, rough distribution of chromatin in cells, an increase in the number of nucleoli, detection of mitotic division figures. The formulation of the cytological conclusion is important for the correct assessment of the data obtained by clinicians. The classification of cytological conclusions according to Papanicolaou is most widely used in the world. It includes 5 groups.

• Group I - no atypical cells. Normal cytological picture, not raising suspicions.
• Group II - changes in the morphology of cellular elements caused by inflammation.
• Group III - there are single cells with abnormalities of the cytoplasm and nuclei, but a final diagnosis cannot be established. A repeat cytological examination is necessary, and, if recommended, a histological one.
• Group IV - individual cells with clear signs of malignancy are detected: abnormal cytoplasm, altered nuclei, chromatin aberrations, increased nuclear mass.
• Group V - smears contain a large number of typically cancerous cells. The diagnosis of a malignant process is beyond doubt.

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