Correlation between cytological and histopathological examination of the endometrium in abnormal uterine bleeding.

BACKGROUND: Abnormal uterine bleeding (AUB) is a common problem for which women seek gynecological consultation. Endometrial aspiration cytology (EAC) is an acceptable and valuable diagnostic procedure for screening the endometrial status.
MATERIALS AND METHODS: Endometrial aspiration using a menstrual regulation (MR) syringe and a 4 mm Karman's cannula was performed just prior to D and C in 100 women presenting with AUB. Smears were reviewed for cytomorphological findings and were correlated with the histopathological findings. These findings were categorized as benign endometrium, endometrial hyperplasia, malignancy and inadequate smears.
RESULTS: Age of the patients ranged from 19 to 70 years. In our study, the accuracy in diagnosing benign conditions of endometrium, hyperplasia, and malignancy on aspiration cytology were 93.88%, 96.94% and 96.84%, respectively.
CONCLUSIONS: Endometrial aspiration is an effective, useful and a minimally invasive procedure. With an experienced cytologist, it can be used routinely for the primary investigation of women with AUB, provided all the points of discrepancies are taken care of.

Introduction

Abnormal uterine bleeding (AUB) is characterized by bleeding at abnormal or unexpected times or by excessive flow at the time of an expected menses.[1] Dilatation and curettage (D and C) has for long been considered the “gold standard” in the diagnosis of endometrial pathology.[2] One of the most commonly performed gynecological surgery, it accounts for a large proportion of hospital bed use and operating room time. The cost is significant and carries the complications of anesthesia. For these reasons, there is a need for a simple, accurate and good out-patient department (OPD) procedure as an alternative to D and C. Endometrial aspiration cytology (EAC) can be used as a safe, minimally invasive and reliable OPD procedure with minimum discomfort to the patient.[3]

Various endometrial sampling devices have been developed and tested, among which are the Mi-Mark Helix, the Curity - Isaacs endometrial cell sampler, Endocyte, Vakutage, Gravlee jet irrigator, Endo-pap sampler, uterobrush, Vabra aspirator, Endogyn device, a simple disposable syringe, menstrual regulation (MR) syringe with a Karman's cannula etc.[24] Hemalatha et al.[3] used MR syringe with a Karman's cannula as a direct endometrial sampling device and found the technique to be simple, reliable and well accepted by patients. It can be used for the detection of a wide variety of benign lesions of endometrium and screening for malignancy.

Cancer of the uterine corpus is the most common pelvic gynecologic malignancy in developed countries, with its incidence rising in developing countries.[5] Patients with a higher risk for harboring endometrial cancer might benefit from an effective and low-cost screening test for endometrial cancer. Earlier tumor detection in such patients offers the opportunity to improve patient survival.[6] Cytological examination of the endometrium is particularly useful in postmenopausal women having endometrial atrophy that may result in a high inadequacy rate of endometrial biopsies. In this context, endometrial cytological samples have been shown to be diagnostic in a significantly higher percentage of cases with respect to biopsy samples (82% vs. 24%).[7] The objective of the present study was to describe the spectrum of lesions along with their cytomorphological features and compare the results of EAC with subsequent histopathology in order to assess the value of the former and its shortcomings.

Materials and Methods

The present prospective study was conducted on 100 female patients of all age groups attending the Department of Obstetrics and Gynecology over a period of 2 years with a clinical diagnosis of AUB. Patients having acute inflammatory disorders of the genital tract, a viable pregnancy and cervical carcinoma were excluded from the study. After obtaining a detailed clinical history, the patients went through a physical examination and all relevant investigations were carried out. The procedure was well-explained to the patients, and their consent was taken. Under all aseptic conditions, endometrial aspiration was carried out in the OPD or in the operation theater prior to curettage. An MR syringe with a 4 mm Karman's cannula was used for aspiration. Material obtained was expelled onto clean glass slides, smears were prepared, air-dried, followed by fixation in methanol. These were stained with May-Grünwald-Giemsa stain. One of the slides was immediately fixed in 95% ethyl alcohol and then stained with Papanicolaou stain. Subsequently, all the patients were subjected to D and C, the curettings obtained were fixed in 10% formalin. After tissue processing, sections were obtained and stained with hematoxylin and eosin (H and E) stain. Finally, cytological and histopathological results were compared.

The cytomorphological criteria used in various conditions of the endometrium were as given by An-Foraker et al.[8], Shu et al.[9] and Meisels et al.[10] The factors of inadequacy were followed as stated by Veneti et al.[11] that the reason of histologically and cytologically inadequate material could be old age, uncooperation by the patient or technical errors. The number of such cases may be reduced with more experience since the inadequate cases were found in the first part of their study.

Statistical analysis

Correlation of cytology with histopathology was evaluated by applying the screening tests of sensitivity, specificity, predictive value of a positive test, predictive value of the negative test, percentage of false positives and percentage of false negatives.

Results

The present study was carried out on 100 female patients presenting with AUB, and the age ranged from 19 to 70 years with most of them being in the fourth and fifth decades of life (68%).

The chief pattern of AUB was menorrhagia (48%), followed by amenorrhea and postmenopausal bleeding (14% each), menometrorrhagia (13%), metrorrhagia (8%), polymenorrhea (2%) and oligomenorrhea (1%).

The results of 100 cytological aspirations in the present study were broadly categorized as follows:

Benign endometrium, including normal phases of endometrium, irregular and atrophic endometrium, as well as decidual reaction (70 cases).

Hyperplasia (18 cases).

Malignancy (adenocarcinoma), which included endometritis with a suspicious pathology (12 cases).

Inadequate or unsatisfactory smears (no case).

Excluding the 5 cases, which were labeled as inadequate on histopathology, the cytological and histopathological findings were compared [Table 1].

Table 1

Correlation of cytological and histopathological findings in 95 cases (excluding the five inadequate cases on histopathology)

Benign endometrium

Including normal phases of endometrium, irregular and atrophic endometrium, as well as decidual reaction.

In the present study, 70 cases were placed in this category on cytology, out of which 62 cases proved to be benign, 3 cases were of hyperplasia and rest of the 5 cases had inadequate material on histopathology. To be precise [Table 1], after excluding the inadequate cases, 23 cases showed proliferative activity, uniform sized endometrial cells being present in sheets with regular, round, darkly stained nuclei showing uniform chromatin pattern and a thin rim of cyanophilic cytoplasm on cytology [Figure 1a]. Of these, 20 were consistent, and the remaining three showed simple hyperplasia on histopathology. Sixteen cases showed secretory phase on cytology, the cells being present in sheets with vacuolated cytoplasm and slightly vesicular nuclei forming honey-comb pattern [Figure 1b] as well as on histopathology. One extra case which was diagnosed as secretory on histopathology was shown to be malignant on cytology. This case was a 69-year-old female who was postmenopausal since 15 years, had spotting about a year back and had now presented to the gynaecology OPD complaining of excessive bleeding since 1-week. On aspiration cytology, there were cell clusters with polymorphonuclear infiltration surrounded by necrosis. There were large cells, mostly polygonal in shape with abundant eosinophilic cytoplasm. The nucleus was round to oval, enlarged with a prominent nucleolus and at places, gave a suspicious look. So, a diagnosis of endometritis with a suspicious pathology was given on cytology [Figure 2a].

Figure 1

Aspira.. on cytology (a) prolifera.. ve endometrium - A group of endometrial cells with small darkly stained nuclei and a thin rim of cytoplasm (MGG, ×400). (b) Secretory endometrium - A group of endometrial cells with vacuolated cytoplasm and slightly vesicular nuclei (MGG, ×400)

Figure 2

Aspiration cytology (a) endometritis with suspicious pathology - A loose cluster of atypical cells infiltrated with numerous inflammatory cells (MGG, ×400). (b) Irregular or mixed endometrium - Two groups of endometrial cells, one showing proliferative phase (top left ) and the other showing secretory phase (bottom right) (MGG, ×100)

There were 6 cases of irregular or mixed endometrium containing both secretory and proliferative elements on both cytology [Figure 2b] and histopathology. On cytology, there were 6 cases of atrophic endometrium (excluding the inadequate case) where cellular sheets were rarely seen, the nuclei were small and darkly stained with scanty cytoplasm and all six were proved on histopathology. Two extra cases, which were atrophic on histopathology, were diagnosed as malignant on cytology. Fourteen cases (after excluding the inadequate case) showed decidual reaction on cytology, the decidual cells being round to polygonal in shape with abundant eosinophilic cytoplasm and sharp, distinct borders [Figure 3a]. The centrally placed nucleus was enlarged with a round to oval shape, had dense chromatin and contained a prominent nucleolus. All the 14 cases were proved on histopathology.

Figure 3

Aspiration cytology (a) decidual reaction - round to polygonal decidual cells with abundant cytoplasm and enlarged nuclei (MGG, ×400). (b) Endometrial hyperplasia-Overlapping of both, glandular and stromal cells with little or no visible cytoplasm (MGG, ×400)

Hyperplasia

In the present study, 18 cases were diagnosed as hyperplasia [Figure 3b] on cytology and all were proved on histopathology. There was overlapping of cells in glandular clusters or sheets, presence of nucleoli, anisokaryosis, granularity of chromatin and presence of stromal cells. However, 3 cases diagnosed as benign on cytology (proliferative phase) subsequently turned out to be hyperplasia on histopathology [Table 1]. Thus, there were 21 cases of hyperplasia on histopathology in the present study.

Malignancy

(Including malignant cases as well as those diagnosed as endometritis with a suspicious pathology on cytology).

In the present study [Table 1], 12 cases were placed in this category on cytology [Figure 4] out of which 9 cases was proved to be malignant on histopathology. Out of the remaining 3 cases, 2 cases were diagnosed as atrophic endometrium with endometritis and 1 case as secretory endometrium that also showed foci of decidual change on histopathology. Smears showed increased cellularity with crowding, disorganization and variation of cellular and nuclear sizes in sheets of cells; extreme variation of shape and size of cells; increased nuclear chromatin granularity; increased size, altered shape and increased number of nucleoli; abnormal mitotic figures; loss of cellular cohesiveness and; cancer diathesis.

Figure 4

Aspiration cytology of endometrial malignancy (adenocarcinoma) (a) Malignant cells present in irregular papillary clusters (Pap, ×400). (b) Highly pleomorphic cells with hyperchromatic nuclei and prominent nucleoli (MGG, ×1000)

Inadequate

In the present study, there was no inadequate smear on cytology as all the cases, which were found inadequate, were subjected to re-aspiration due to its ease and convenience. On histopathology, 5 cases showed inadequate material.

On statistical evaluation, the sensitivity of diagnosing benign endometrium, hyperplasia and malignancy was 95.59%, 87.5% and 100%, respectively and the specificity was 90%, 100% and 96.51% respectively [Table 2].

Table 2

Statistical evaluation

Discussion

Endometrial aspiration is not a very popular and well accepted procedure in India due to various reasons. One of the factors is the unavailability and the high cost of the aspiration instrument. To overcome this obstacle, we used an MR syringe and Karman's cannula which is a low-cost device. The other factors being that the diagnostic criteria of endometrial cytology have not yet been fully established. Though endometrial histology is the confirmatory test in our study, yet we should resort to EAC as a routine preliminary procedure in women with AUB as it is a easier, safer and reliable OPD procedure. Moreover, in cases of inadequacy, this procedure can be repeated without much inconvenience to the patient, as was done in our study.

Hemalatha et al.[3] used MR syringe and a 4 mm Karman's cannula for endometrial aspiration to compare cytological and histopathological findings in cases of dysfunctional uterine bleeding. The material was adequate in 95% of cases for cytology. The correlation with D and C was found to be 95% with a diagnostic accuracy that was greater with aspiration than with D and C. In the present study, all the cases which were found inadequate on cytology were subjected to re-aspiration. So, there was no inadequate case on cytology in our study.

In the present study, age ranged from 19 to 70 years with a mean of 38.96 ± 10.6 years. It was comparable to the mean age (44 years) of 51 patients selected for the study by Liza et al.[12] in which the age-range was 39-70 years. In the present study, maximum cases (39%) belonged to 4th decade that was comparable with 42.20% in the study by Maheshwari et al.[13].

The percentage accuracies in diagnosing benign conditions of endometrium, hyperplasia and malignancy on aspiration cytology in our study were 93.88%, 96.94% and 96.84% respectively and were comparable to that of Kyroudi et al.[14] in cases of benign conditions (96.2%) and hyperplasia (92.5%) and to Segadal et al.[15] and Papaefthimiou et al.[16] in cases of malignancy (95.7% and 98.7% respectively).

Endometrial cytology was unable to diagnose 3 cases of hyperplasia, all three of which were reported as proliferative due to the fact that the exaggerated proliferative pattern which is seen in hyperplasia was missed on cytology. Second, on histopathology, nine of the 12 cases proved to be malignant. Out of the remaining 3 cases, 2 cases were diagnosed as atrophic endometrium with endometritis and 1 case as secretory endometrium that also showed foci of decidual change on histopathology. This discrepancy could be due to the fact that endometritis complicates the cytological findings. Inflammation obscures cellular detail. The inflammatory debris may be confused with tumor diathesis. Inflammatory smears may assume all the characteristics of endometrial cancer cells including enlarged nuclei with variation in size, even in shape, hyperchromasia as well as prominent and multiple nucleoli. Atrophic smears could be a pitfall due to their dark staining nuclei. Furthermore, in endometritis and decidual change, on aspiration cytology, there were cell clusters with polymorphonuclear infiltration surrounded by necrosis. There were large cells, mostly polygonal in shape with abundant eosinophilic cytoplasm. The nucleus was round to oval, enlarged with a prominent nucleolus and at places, gave a suspicious look.

In terms of malignancy, sensitivity was 100%, specificity was 96.51%, with three false positive and no false negative case in the current study. The three false positive cases were seen when there was accompanying endometritis. Hence, accuracy is 100% in the cytological diagnosis when endometritis is not present. It is important to note that in no case was a malignancy missed on cytology. Hence, EAC is clearly of special value as the preliminary investigation of women with postmenopausal bleeding or those who are at a risk of endometrial carcinoma.

Conclusions

We thus conclude from the study that endometrial aspiration is an effective, useful and a minimally invasive procedure. A very important criterion is the cytologist's ability in reporting the findings. With an experienced cytologist, it can be used routinely for the primary investigation of women with AUB, provided all the points of discrepancies are taken care of. Endometrial aspiration is of special value in the investigation of women in whom there are much greater risks associated with general anesthesia and in whom no curettings are obtained. This technique would eliminate an endometrial curettage in those patients in whom there is no clinical suspicion of endometrial carcinoma, and the cytology is negative. Unnecessary hospital expenditure as a result of indoor admissions and anesthesia required for D and C can be avoided. We hope that this study will inculcate further interest amongst the gynecologists and cytologists and a good coordination among them is required to make aspiration cytology a routine screening procedure.