Imaging: Ultrasound, MRI and CT Scan
Reviewed by: HU Medical Review Board | Last reviewed: June 2018 | Last updated: July 2022
After taking your medical and symptom history, and after performing a pelvic exam, your provider may recommend imaging. Imaging exams, such as ultrasound, MRI, or CT scans are used to take pictures of the inside of your body. They're used for a wide variety of purposes, including assessing injuries, monitoring the growth of a developing baby, looking for internal growths or tumors, and much more.
The only way to receive a definitive diagnosis of endometriosis is during a laparoscopy. A Laparoscopy a minimally invasive procedure that involves inserting a small, thin, camera-containing tube into the abdomen that can see endometriosis lesions. However, even if your provider suspects that you may have endometriosis, they may still recommend imaging. One reason they might recommend this is because they're still ruling out other possible conditions. Endometriosis shares similar symptoms with a variety of different issues, including inflammatory bowel disease, pelvic inflammatory disease, and more. Imaging exams might show signs of one of these other conditions, leading to a diagnosis other than endometriosis. It's also possible that your imaging exams appear completely normal, which might lead your provider to recommend a laparoscopy for further examination.
Although the effectiveness of imaging exams in detecting potential signs of endometriosis is not as strong as laparoscopy, it is possible that some images may uncover endometriosis-related issues such as deep infiltrating endometriotic nodules or endometriomas (endometriosis-related ovarian cysts). This could help determine the extent of an individual's endometriosis. However, other conditions can cause ovarian cysts or other deeply infiltrating masses within the pelvis, so a laparoscopy may still be needed to definitively diagnose endometriosis despite seeing these findings on an image.1-3
Ultrasound imaging involves the use of sound waves, and is also called sonography or ultrasound scanning. To take an ultrasound image, a transducer is used. The transducer gives off high frequency sound waves and these waves disperse through the body at the area where the transducer is placed, however, these waves are at such a high frequency that humans can't hear them. Once they are emitted into the body, the waves bounce off of the structures inside. When a wave bounces off of a structure, like the bladder as an example, the wave travels back to the transducer. The length of time and patterns in which these waves come back to the transducer is what allows for an ultrasound image to be created. These waves are continuously moving and follow the transducer, producing real-time images called sonograms. The ultrasound process and the sound waves created are not painful.
The transducer is often placed on the outside of the body, however, when imaging the female reproductive system and its surrounding structures, a transvaginal ultrasound may be used. If a woman has a transvaginal ultrasound, a small, lubricated transducer will be gently inserted into her vagina. Your provider can tell you which approach you may encounter and how to best prepare for your ultrasound exam.4
MRI (magnetic resonance imaging) exams use radio frequency pulses and a magnetic field to create detailed images of the inside of your body that will be sent to a computer in another room. MRI does not involve radiation. Although the magnetic field doesn't harm the body, it is important to remove all jewelry or accessible metal from your body before the exam begins. If you have an internal medical device, alert your provider or the MRI technician before the procedure begins, as MRI may impact the way certain medical devices function. When undergoing an MRI, it's necessary to stay as still as possible.
An MRI machine has a tube-like opening that the individual undergoing the exam will be guided into. How far an individual is placed into the machine depends on where in the body images will be taken. For example, if an individual is undergoing an MRI of the knee, they most likely will only be in the machine up to their thigh. If they are undergoing an MRI of their abdomen or chest, they may need to be placed further into the machine. If you are uncomfortable in enclosed spaces, alert your provider or the MRI technician before (or during) the exam. Some facilities have MRI machines that are open and don't completely surround you. MRI machines may also be designed in different sizes to accommodate larger individuals.5
CT (computed tomography), also called a CT scan or a CAT scan, utilizes x-rays to create pictures of your body. Unlike a traditional x-ray that produces one picture from one angle within your body, CT scans utilize many different x-rays at once that rotate around you to create a detailed, multidimensional image on a monitor nearby. Because CT uses radiation, it's important to alert your provider or your CT technician if you know you are pregnant or think you may be pregnant before the exam begins. Like an MRI machine, a CT scanner is a tube that completely surrounds you, however, CT scans are much quicker than MRI's, often finishing within 10 to 30 seconds. If you are apprehensive about the CT scanner, let your provider or the CT technician know before or during the exam, so that they can help address your concerns and make adjustments if needed.6