Can a Normal Biopsy Miss a Uterine Polyp? Hysteroscopy

Yes, a normal endometrial (uterine lining) biopsy can miss a uterine polyp or other localized abnormality. An office biopsy is a “blind” procedure that randomly samples only a small fraction of the uterine lining ^[1]. While it is generally excellent for detecting widespread conditions, it can miss a polyp if the sampling instrument does not pass directly over it. Because of this, if your symptoms persist or your imaging suggests a polyp, your clinician may recommend further evaluation, which often includes a hysteroscopy.

What a “Blind” Biopsy Can and Cannot Show

An office endometrial biopsy (often done with a thin suction tube called a Pipelle) is considered a “blind” procedure because it is performed without a camera. The instrument relies on suction to pull in tissue as it passes through the cavity, typically sampling only a small percentage of the endometrial surface ^[1].

A uterine polyp is a focal lesion, meaning it is an abnormal growth located in one specific, localized spot. Because the biopsy tool is moved blindly, it can easily sample the healthy, normal tissue right next to the polyp while missing the polyp itself ^[1]. Studies illustrating this limitation in specific groups of women with abnormal bleeding have shown that blind office biopsies missed roughly two-thirds of the polyps that were eventually found ^[2][3].

Additionally, it is important to distinguish between a “benign” (normal) biopsy and an insufficient (nondiagnostic) biopsy. An insufficient result means the lab did not get enough tissue to make any diagnosis at all. In women with postmenopausal bleeding, one systematic review found that up to 31% of blind biopsies were insufficient, a result that requires follow-up rather than being treated as normal ^[4].

When Hysteroscopy is Considered

To overcome the limitations of a blind biopsy, clinicians often use hysteroscopy. This procedure involves inserting a thin, lighted camera through the cervix and into the uterus, allowing the doctor to visually inspect the inside of the cavity ^[5][6]. Instead of hoping to catch abnormal tissue by chance, the clinician can see the lesion and aim to remove it completely (a procedure called a hysteroscopic polypectomy) ^[5]. Medical guidelines favor this type of visually directed biopsy over blind sampling when evaluating focal abnormalities ^[6][7].

Your clinician may recommend a hysteroscopy after a normal biopsy based on several individualized factors:

• Persistent or Recurrent Bleeding: If abnormal bleeding continues, a normal biopsy is not the final answer ^[8]. Further investigation is required.
• Suspicious Imaging Results: If a standard ultrasound or a saline-infused sonogram (an ultrasound using sterile fluid to gently expand the uterus for better visibility) shows a suspected polyp or a submucosal fibroid (a benign muscle tumor pushing into the cavity), visual evaluation is often the next step ^[6][2].
• Menopause Status and Risk Factors: Any bleeding after menopause requires a clinical evaluation, and if it persists after a benign biopsy, more testing is needed ^[9][10]. Clinicians also consider risk factors like obesity, diabetes, and the use of unopposed estrogen (taking estrogen without the progesterone normally needed to protect the uterine lining) ^[9][10].
• A Thickened Uterine Lining: In a specific trial of women with postmenopausal bleeding and a thickened uterine lining (over 4 mm) who had a benign blind biopsy, follow-up hysteroscopy found polyps in 51% and localized precancer (abnormal cells that can turn into cancer) or cancer in 6% ^[11]. While these numbers apply specifically to that study population, they illustrate that a normal blind sample does not guarantee the entire cavity is free of disease ^[11].

What to Expect and Potential Alternatives

Hysteroscopy evaluates the inside of the uterine cavity, but it is important to remember that abnormal bleeding can also come from hormonal changes, medications, or areas outside the uterus (such as the cervix or vagina). Depending on your situation, alternatives like repeat sampling or different imaging might be reasonable first steps.

If you proceed with a hysteroscopy, it may be performed in an office or an operating room. Pain control options can range from local anesthesia to sedation or general anesthesia. While generally safe, hysteroscopy carries risks, including cramping and spotting, and less commonly, infection, a small tear in the uterus (perforation), or complications from the fluid used to expand the uterus. Patients should always ask their care team when to seek urgent help after the procedure, which typically includes symptoms like heavy bleeding, fever, fainting, or severe, worsening pain.