Blad w skryningu

This content is also available in: English Italiano Español Čeština Magyar

Bookmark (0)

No account yet? Register

B??d w skryningu i potrzeba zapewnienia jako?ci

Zapewnienie jakosci jest nieodzowne dla zmniejszenia ryzyka bledów w cytologii szyjki macicy.

Istnieja 3 glówne typy bledów:

  1. B??dy zwi?zane z  pobieraniem materia?u.
  2. B??dy zwi?zane z procesem laboratoryjnym.
  3.  B??dy zwi?zane z interpetacj?.

Do 10% rozmazów pochodzacych od kobiet ze zmianami przedrakowymi lub wczesnym rakiem inwazyjnym szyjki macicy moze nie zawierac nieprawidlowych komórek. Istnieja trzy mozliwe wyjasnienia tej sytuacji:

  1. B??dy w pobieraniu i wykonywaniu rozmazu:
    1. Obszar strefy transformacji nie zosta? wystarczaj?co obj?ty w trakcie pobierania materia?u
    2. Nieprawid?owe komórki nie zosta?y przeniesione ze szpatu?ki na szkie?ko
    3. Zmiana CIN mo?e by? ma?a i/lub wysoko zlokalizowana w kanale szyjki macicy, poza zasi?giem szpatu?ki
  2. B??y w utrwalaniu i opracowaniu technicznym rozmazu:
    1. Morfologia komórek nie jest wystarczaj?co zachowana
    2. Stosunek j?drowo/cytoplazmatyczny zaburzony
    3. Obrysy j?dra i struktura chromatyny s?abo zachowana
    4. Blade wybarwienie j?dra i brak kontrastu j?dro/cytoplazma
    5. B??d w oznaczaniu preparatu
  3. B??dy w interpretacji rozmazu
    1. Spadek koncentracji w czasie skryningu
    2. Przyzwyczajenie – Pod?wiadomy proces, w którym mózg ignoruje powtarzaj?cy si? sygna?.
    3. Rozpraszanie uwagi w trakcie skryningu (rozmowa telefoniczna)
    4. Niedostateczny skryning ca?ego preparatu
    5. Zm?czenie (skrining zbyt du?ej liczby preparatów)
    6. Niewystarczaj?ce wyposa?enie optyczne mikroskopu lub 
    7. B??d w trakcie pisania wyników

Pitfalls of Diagnosis

False negative reports are issued when the cytologist fails to detect abnormal cells which are present in the smear .There have been several studies to determine the characteristics of false negative smears.  These have shown that  the risk of a false negative smear report being issued is very high if the smear contain relatively few ( < 50 ) abnormal cells.  Unfortunately studies have also shown that  the majority of  false negative smear reports are issued  in cases where the   smears contain  a very large number of abnormal cells indeed.  In fact , in retrospective studies of women who have presented with invasive cancer it has been found that  up to three or more consecutive false negative reports have been issued over a period of several years before  invasive cancer was diagnosed . False negative reports are particularly harmful  because they result in failure to diagnose or treat the patient’s cancer.

False Positive reports are issued when the negative smears are reported to contain abnormal cells . In these cases the patient may undergo unnecessary surgical procedure  and may be alarmed unnecessarily.
A number of conditions have been recognised which may give rise to  problems of interpretation  leading   to  a false positive diagnosis. These so called pitfalls in diagnosis are listed and several are illustrated below

Pitfalls in diagnosis

  1. Small cell dyskariosis
  2. Follicular lymphocytic  cervicitis
  3. CIN3 minibiopsies  ( microbiopsies ) or CIN involving crypts
  4. Discrete small keratinised cells
  5. Endometriosis , tubo endometrioid  metaplasia
  6. Lower segment endometrium
  7. Immature metaplastic cells
  8. Histiocytes
  9. radiation changes
Radiation changes : the anisonucleosis in this cluster of  
squamous  cells is marked but the nuclear structure is bland and the cytoplasm abundant. It is important to take note of the   clinical history when interpreting a smear.
Immature metaplastic cells: The slight anisonucleosis and hyperchromasia in this cluster of cells led to a diagnosis of ASCUS . Colposcopy and subsequent cytology were negative .
Immature metaplastic cells: The slight anisonucleosis and hyperchromasia in this cluster of cells led to a diagnosis of ASCUS . Colposcopy and subsequent cytology were negative .
These epithelial cells were present in a follow up smear from a woman who had LLETZ for CIN3.They were reported as suspicious of recurrence/residual CIN but colposcopy and follow up cytology was negative .They are probably immature metaplastic cells.

A dense cluster of poorly differentiated malignant squamous cells from a case of invasive squamous carcinoma . High power microscopy of the edge of the cluster reveals the crowded overlapping hyperchromatic nuclei which vary in shape and size and have abnormal chromatin content.

A dense cluster of poorly differentiated malignant squamous cells from a case of invasive squamous carcinoma . High power microscopy of the edge of the cluster reveals the crowded overlapping hyperchromatic nuclei which vary in shape and size and have abnormal chromatin content.
This smear was from a case of invasive squamous carcinoma. Note the numerous discrete small keratinised cells Note also the malignant diathesis. Elsewhere in the smear there were severely dyskariotic cells.

 

UWAGA

Do 45% rozmazów pochodzacych od kobiet z zaawansowanym rakiem moze nie zawierac komórek rakowych. Zdarza sie tak dlatego, ze zmiany sa czesto martwiczo zmienione i owrzodziale, a wówczas rozmaz zawiera wylacznie krew neutrofile i masy martwicze (tzw. diathesis maligna). Cytotechnicy moga zminimalizowac ten problem przez systematyczna ocene rozmazu pod katem jego adekwatnosci i informowanie osoby pobierajacej wymaz o jakosci rozmazu.