Endometrial Biopsy

Endometrial biopsy takes a sample of endometrial tissue for histological examination, usually with a flexible aspiration catheter passed through the cervix in the outpatient setting. It is a direct sampling method and is more accurate than transvaginal ultrasound alone for diagnosing endometrial hyperplasia and malignancy.

Sampling can miss focal lesions, such as polyps, so a negative biopsy does not exclude every pathology.

Usage. It is used for abnormal uterine bleeding, unexplained postmenopausal bleeding, persistent endometrial thickening, and surveillance of endometrial hyperplasia.

Indications. Postmenopausal bleeding, persistent abnormal uterine bleeding in women aged 45 or over, younger women with risk factors for endometrial cancer, endometrial thickness over the local threshold, and surveillance of hyperplasia.

Preparation and technique. Pregnancy is excluded. The biopsy is performed in the proliferative phase where possible in premenopausal women, since the secretory phase can cause difficulty in interpretation. The cervix is cleaned, and a catheter is passed into the cavity. Suction is applied, and the sample is withdrawn and placed in formalin.

Contraindications and precautions. Pregnancy, active pelvic infection, and cervical stenosis that prevents passage of the catheter. Vasovagal reactions, cramping and minor bleeding are common, and analgesia is offered.

Interpretation.

• Histology reports proliferative, secretory or atrophic endometrium.
• Endometrial hyperplasia is classified by architecture and cytological atypia, and atypical hyperplasia is treated as a precursor of malignancy.
• Endometrial carcinoma is reported with histological type and grade.

Causes of an inadequate sample. Insufficient tissue, cervical obstruction, and sample loss in transit.

Critical values and findings needing immediate action.

• Malignancy or atypical hyperplasia requires urgent specialist referral.
• Severe uterine bleeding with haemodynamic instability requires immediate management, regardless of the sample result.

Limitations and artefacts. Sampling is blind, so focal lesions such as polyps may be missed. Hormone therapy changes the endometrial appearance. An inadequate sample is a common reason for a non-diagnostic result.

Follow up tests. Hysteroscopy with targeted biopsy, transvaginal ultrasound to assess endometrial thickness, and repeat biopsy at an interval determined by the histology.

Complications. Vasovagal reaction, cramping, infection and uterine perforation, which is rare.

Special groups. Postmenopausal women on hormone therapy have different thresholds for thickness and interpretation. Adolescents are examined only where the indication is clear. Pregnancy excludes the procedure.