A pelvic ultrasound is a common, non-invasive diagnostic tool used in gynecology that utilizes high-frequency sound waves to generate real-time images of the uterus and ovaries. The procedure is routine when a patient presents with symptoms or when a healthcare provider needs to visualize internal structures. The two primary methods employed are the transabdominal and the transvaginal ultrasound. A transabdominal scan, performed over the lower abdomen, provides a wider overview of the pelvis. The transvaginal method involves inserting a small probe into the vagina to achieve greater detail and closer images of the reproductive organs.
Diagnosing Common Complaints
The ultrasound is frequently ordered when a patient reports specific symptoms, such as abnormal uterine bleeding (AUB) or unexplained pelvic pain. For AUB, the primary focus is measuring the thickness of the endometrial lining. This is an important indicator, especially in postmenopausal women, where a thickness of 4 millimeters or less is associated with a low likelihood of endometrial cancer.
In premenopausal women, endometrial thickness naturally fluctuates, but the ultrasound helps identify if bleeding is due to structural issues within the uterine cavity. When investigating pelvic pain, the ultrasound serves to quickly rule out acute, time-sensitive gynecological emergencies. If the patient has a positive pregnancy test, a transvaginal scan helps determine if an ectopic pregnancy is present.
The scan also assesses the presence of free fluid in the pelvis, which can be a sign of internal bleeding or inflammation. Free fluid may indicate a ruptured ovarian cyst or other acute condition that requires immediate attention. The ultrasound allows the clinician to localize the source of the pain, differentiating between uterine, ovarian, or surrounding area issues.
Evaluating Structural Changes
When a physical exam or symptoms suggest a structural abnormality, the ultrasound is the definitive tool for characterizing the finding. It is the most effective method for detecting and characterizing masses. This detailed imaging helps distinguish between benign findings that require no intervention and those that need monitoring or treatment.
Ovarian cysts are a frequent finding, and the ultrasound helps classify them as simple or complex. A simple cyst is typically fluid-filled, well-circumscribed, and appears anechoic, or black, often requiring no follow-up. Conversely, complex cysts may contain internal septations, solid components, or irregular walls, which may warrant further investigation or surgical removal.
The scan also identifies uterine fibroids by evaluating their size, number, and location within the uterine wall or cavity. Fibroids that distort the uterine cavity are more likely to cause heavy bleeding or affect fertility. Endometrial polyps are visualized by the ultrasound, often requiring specialized techniques like saline infusion sonohysterography for better delineation. Characterization of these masses determines the appropriate next steps, such as observation or treatment.
Monitoring Fertility and Known Conditions
The utility of a gynecological ultrasound extends beyond diagnosing immediate problems into the proactive management of fertility and chronic conditions. In fertility treatment, transvaginal ultrasound is the standard method for follicular monitoring. The scan precisely measures the diameter of ovarian follicles, with a size of 18 to 20 millimeters often indicating maturity and readiness for ovulation.
Simultaneously, the ultrasound measures the thickness and appearance of the endometrial lining, which must reach a sufficient thickness, typically around 8 millimeters, to support embryo implantation. This monitoring is repeated every few days to pinpoint the optimal timing for intercourse, intrauterine insemination, or egg retrieval in an IVF cycle.
The scan is used for surveillance of known conditions, such as small cysts or asymptomatic fibroids, to track changes in size over time. The ultrasound is also a tool for confirming the correct placement of an intrauterine device (IUD) following insertion. Regular checks of the IUD’s position ensure the contraceptive remains effective.