Uterus, Ovaries and Adnexa Flashcards
What is the space of Retzius?
Describe the displacement pattern for a mass in the space of Retzius.
- The space of Retzius is an extraperitoneal potential space between the pubic symphysis and the bladder.
- A mass in the space of Retzius (such as a hematoma) can displace the bladder posteriorly.
- In contrast, pelvic or abdominal masses will displace the bladder inferiorly or anteriorly.
Describe the cervix in US
What is a Nabothian cyst?
- The cervix is seen transvaginally in the sagittal plane as the most proximal portion of the uterus directly posterior to the angle of the bladder.
- The cervix is attached to the posterior edge of the bladder by the parametrium.
- The cervix and uterus normally form a 90-degree angle.
- Nabothian cysts are normal retention cysts due to occlusion of cervical glands.
Describe the true and false pelvis
- The linea terminalis is a bony landmark separating the true (inferior) pelvis from the false / superior pelvis. The linea terminalis is a composite of the arcuate line of the ilium, the iliopectineal line, and the pubic crest.
- Normally, the uterus and ovaries are in the true pelvis.
- The dome of a full bladder extends into the false pelvis, pushing small bowel out of the true pelvis. The bladder acts as a sonographic window into the true pelvis.
Describe normal variant uterine positions
- About 20 degrees of uterine anteflexion is normal. As the bladder fills, the degree of anteflexion decreases.
- Retroversion of the uterus may cause poor visualization of the fundus transabdominally.
- Retroflexion of the uterus may cause even more severe sound attenuation of the uterine fundus.
Describe orientation of uterus via transabdominal US
Describe the uterine scanning orientation in a endovaginal US
- The sagittal scan plane is rotated 90 degrees between transabdominal and endovaginal orientation. The patient typically empties her bladder prior to endovaginal scanning.
What else should be evaluated when a congenital uterine abnormality is seen?
- Congenital uterine abnormalities may be associated with urinary tract abnormalities such as renal ectopia or agenesis. The kidneys should be evaluated if a uterine malformation is seen.
The American Fertility Society (now known as the American Society of Reproductive
medicine) Mullerian duct anomalies - Class I
Uterine Agenesis/hypoplasia
The American Fertility Society (now known as the American Society of Reproductive
medicine) Mullerian duct anomalies - Class II
Unicornuate uterus
A unicornuate uterus represents a uterine malformation where the uterus is formed from one only of the paired Müllerian ducts while the other Müllerian duct does not develop or only in a rudimentary fashion.
The American Fertility Society (now known as the American Society of Reproductive
medicine) Mullerian duct anomalies - Class III
- A didelphys uterus is two completely separate uteri and cervices, with complete endometrium, myometrium, and serosal surfaces on each side. 75% have a vaginal septum.
The American Fertility Society (now known as the American Society of Reproductive
medicine) Mullerian duct anomalies - Class IV
- A bicornuate uterus has two uterine fundi, with a shared proximal lower uterine segment.
- A bicornuate uterus may be bicornis bicollis (two cervices) or bicornis unicollis (one cervix).
The American Fertility Society (now known as the American Society of Reproductive
medicine) Mullerian duct anomalies - Class V
- A septate uterus consists of two uterine cavities, divided by a fibrous or muscular septum.
- Septate uterus is the most likely of all uterine anomalies to be implicated in pregnancy loss since the fibrous septal tissue or myometrium is relatively avascular.
- By far most common uterine abnormality
The American Fertility Society (now known as the American Society of Reproductive
medicine) Mullerian duct anomalies - Class VI
- An arcuate uterus is a small inpouching or concave surface of the fundus, which is considered a normal variant rather than an anomaly.
The American Fertility Society (now known as the American Society of Reproductive
medicine) Mullerian duct anomalies - Class VII
- In utero exposure to diethylstilbestrol (DES) causes the fetus to develop a hypoplastic uterus with a T-shaped endometrial contour and is associated with an increased risk of clear cell vaginal cancer. DES hasn’t been used since the 1970s.
Describe the menstrual cycle, including ovarian, endometrial and hormone fluctuations.
Measuring the Endometrium
How and when should it be measured?
- The thickest portion of the endometrium should be measured transvaginally in the sagittal orientation.
- Ideally, the endometrium should be measured in the menstrual phase.
- Endometrial fluid is not included in the measurement: If endometrial fluid is present, the flanking endometrium is measured and the two components are summed.
Cyclical Endometrial Thickness
- Days 1 - 4: Menstrual phase
- Days 5 - 9: Early proliferative
- Days 10 - 14: Late proliferative (preovulatory)
- Days 15 - 28: Secretory
- Endometrial thickness <4 mm. The endometrium is a thin, echogenic stripe in the menstrual phase.
- Endometrial thickness 4 - 8 mm.
- Endometrial thickness 6 - 10 mm. Estrogen effects dominate in the proliferative phase, causing increased functional zone thickness. The endometrium becomes trilaminar with a hypoechoic zone between the endometrial cavity and the peripheral echogenic endometrium.
- Endometrial thickness 7 - 14 mm. Progesterone effects dominate in the secretory phase, causing the functional layer to becomes even thicker, soft, and edematous as the spiral arteries become tortuous. The functional layer increases in echogenicity and becomes isoechoic relative to the basal layer. The endometrium reaches its maximum thickness and echogenicity in the late secretory phase.
What is an endometrial polyp and what is the US appearance?
How is it more definitively diagnosed?
- An endometrial polyp can cause mucous discharge or irregular vaginal bleeding between cycles. Most endometrial polyps are benign, but larger polyps (>1.5 cm) or polyps occurring in postmenopausal patients may have malignant potential.
- Ultrasound shows a focal nodular area of endometrial thickening, often with a feeding vessel by doppler. A polyp is more definitively diagnosed by sonohysterogram, where saline is instilled into the uterus prior to transvaginal ultrasound.
Describe Tamoxifen’s effect on the endometrium and US appearance
- Tamoxifen is an estrogen agonist/antagonist used in the treatment of breast cancer. It acts as an antagonist at the breast and an agonist at the endometrium.
- Tamoxifen can cause endometrial hyperplasia, metaplasia, and carcinoma.
- Ultrasound shows irregular, cystic endometrium, which may simulate endometrial cancer or endometrial cystic atrophy.
- Most women on tamoxifen are screened by ultrasound every 6 months for endometrial carcinoma.
How does endometrial carcinoma present?
Risk factors?
US appearance?
- over 95% of endometrial carcinoma presents with postmenopausal bleeding. The main risk factor for endometrial cancer is prolonged estrogen exposure, which occurs with nulliparity, obesity, late menopause, and tamoxifen.
Under what length should the postmenopausal endometrium normally in a patient that is not bleeding.
- If the patient is not bleeding, the postmenopausal endometrium should be <8 mm thick. Although an incidentally thickened endometrium may be a normal hyperplastic response to estrogen exposure, a thickened endometrium should always be regarded with suspicion for malignancy in a postmenopausal woman.
- If the endometrium is thicker than 8 mm in a postmenopausal woman, the patient should be evaluated further, typically via endometrial biopsy with or without hysteroscopy.
What US finding is most suggestive of endometrial carcinoma?
- Although uncommonly seen in the absence of bleeding, the finding most suggestive of endometrial carcinoma is the presence of ill-defined margins separating the endometrium and the myometrium.
If a patient is bleeding what length would suggest endometrial atrophy?
- If the patient is bleeding and the endometrium is less than 5 mm, the bleeding is caused by endometrial atrophy.
- There is negligible risk of endometrial cancer if the thickness is less than 5 mm.
Postmenopausal bleeding with endometrium thicker than what length may represent endometrial cancer?
What is the average endometrial thickness with endometrial carcinoma?
- Postmenopausal bleeding with an endometrium thicker than 5 mm may represent endometrial carcinoma and further workup is needed. Note that the average endometrial thickness with endometrial carcinoma is 21 mm.
What is endometriosis?
What is an endometrioma and what is its classic US appearance?
- Endometriosis is ectopic endometrial tissue outside of the endometrial cavity.
- An endometrioma is a hemorrhagic focus of ectopic endometrial tissue.
- The classic ultrasound appearance of an endometrioma is a well-defined complex cyst with homogeneous low-level internal echoes and increased through transmission. Small linear echogenic foci are often seen at the cyst periphery. This classic appearance isn’t always seen and occasionally an endometrioma may appear similar to a neoplasm.
- While the ovary is the most common site of involvement, endometriosis may affect the adnexa, pelvic viscera, or even organs outside of the pelvis, such as the brain.
What is adenomyosis, how does it present, and what is its US appearance?
- Adenomyosis is endometrial tissue within the myometrium. Adenomyosis typically presents with menorrhagia and pain.
- Ultrasound shows heterogeneous myometrium, typically more prominent in the posterior wall, associated with subendometrial cysts. The uterus may be globular and enlarged and there is often poor differentiation of the endometrial-myometrial border. Focal adenomyosis, known as an adenoma, may simulate a fibroid.
What are fibroids?
Epidemiology?
US appearance?
What is a lipoleiomyoma?
- Fibroids are extremely common benign tumors of smooth muscle seen in 25% of white women and 50% of black women over age 30.
- The typical ultrasound appearance of a fibroid is a slightly heterogeneous, hypoechoic uterine mass with linear bands of shadowing. Calcification is often seen. May undergo cystic degeneration and appear as an anechoic mass with posterior through transmission.
- A lipoleiomyoma is a variant of fibroid that contains fat and is echogenic.
Describe the anatomy of ovaries and adnexa
- There is a dual blood supply to the ovary:
- The ovarian artery comes directly off the aorta to supply the lateral aspect of the ovary.
- A branch of the uterine artery arises from the internal iliac artery to supply the medial aspect of the ovary.
- The fallopian tube is divided into four segments, from proximal to distal:
- Interstitial (intramural) is the narrowest segment.
- Isthmus.
- Ampulla.
- Infundibulum.
Describe all the cyclical changes within the ovaries
- Day 5-7 of the menstrual cycle: multiple follicles become apparent in the ovary.
-
Day 8-13: one (or more) dominant follicles arise.
- 4-5 days before ovulation, the dominant follicle grows at the rate of approximately 2-3 mm/day.
- The maximal diameter of the dominant follicle is approximately 2 cm.
- The day prior to ovulation, a hypoechoic ring forms around the dominant follicle, which represents the granulosa layer separating from the theca.
- Day 14: ovulation. Physiologic bleeding occurs into the follicle at the time of ovulation, at which point the follicle is called the corpus hemorrhagicum. After ovulation, the corpus hemorrhagicum becomes the corpus luteum.
- Day 15-20: The corpus luteum retains fluid over the next 4-5 days to reach a maximal size of approximately 3 cm.
- Day 20-28. If pregnancy doesn’t occur, the corpus luteum involutes to become the corpus albicans, which cannot be seen by ultrasound.
What are hemorrhagic ovarian cysts and its US appearance (acutely and subacute)?
- A hemorrhagic cyst is the result of hemorrhage into a functional cyst, most commonly a corpus luteum. Ultrasound findings can be suggestive, although a complex cyst should be followed-up at least once to ensure resolution.
What is ovarian hyperstimulation syndrome (OHSS)?
US appearance?
Criteria?
What does OHSS increase the risk of?
- OHSS is a complication of fertility treatment, thought to be due to VEGF dysregulation causing capillary leak.
- The criteria for diagnosis of OHSS include abdominal pain, enlargement of the ovary to greater than 5 cm, and presence of either ascites or hydrothorax. At least one additional laboratory or clinical symptom must be met, including elevated hematocrit (>45%), elevated WBC (>15,000), elevated LFTs, acute renal failure, or dyspnea.
- OHSS increases the risk of ovarian torsion and ectopic pregnancy.
What is a dermoid cyst?
What is another name for dermoid cysts?
US appearance?
How to confirm?
- Dermoid cyst, also called a mature cystic teratoma, is the most common ovarian neoplasm. Technically, a teratoma contains all three primitive germ cell layers, while a dermoid cyst may contain only two. In general use, however, these terms are interchangeable.
- Dermoid cysts are benign. malignant transformation is very rare and typically occurs in postmenopausal patients.
- The classic ultrasound appearance of a dermoid cyst is a complex ovarian cyst with an echogenic Rokitansky nodule, a mural nodule containing solid elements. The imaging appearance can be variable, however, and other common imaging features include:
- The dot-dash pattern describes interrupted echogenic lines thought to be produced by keratin fibers.
- The tip of the iceberg sign describes obscuration of the deeper contents due to high-attenuation material.
- In ambigious cases confirm presence of fat with CT or MR.
DDx for Endometrial Cysts
- The differential diagnosis of endometrial cysts includes
- hemorrhagic functional cysts
- fibrothecoma
- cystic mature teratoma
- cystic ovarian neoplasm
- ovarian abscess.
