Pelvic Inflammatory Disease (PID) is the result of an ascending spread of infection within the pelvis due to a causative organism (most commonly polymicrobial but also due to Chlamydia trachomatis or Neisseria gonorrhoeae infection). The condition is characterized by periovarian inflammation and is most common in women of reproductive age.
Cervical motion tenderness
Elevated inflammatory markers
Ultrasound findings of Pelvic Inflammatory Disease (PID):
Though PID is clinically diagnosed, ultrasound imaging is the first-line radiologic evaluation method of choice for PID and may be used to appreciate the following:
Adnexal mass with heterogenous echogenicity (often bilateral)
Hydrosalpinx is the abnormal accumulation of fluid in the fallopian tubes causing tubal swelling. Common underlying causes of hydrosalpinx include Pelvic Inflammatory Disease, Endometriosis, tubal obstructions/ligations, adhesions, and complications of hysterectomy.
Chronic pelvic pain
Ultrasound Findings of Hydrosalpinx:
While fallopian tubes are not normally visible on ultrasound, the dilated uterine tubes of hydrosalpinx can be visualized by the following characteristics on ultrasound imaging:
Tubular shaped cystic mass discontinuous with the ipsilateral ovary
Waist sign – indentations on both sides of the tubular mass
Beads-on-a-String sign – cross-sectional view with incomplete septations associated with chronic pelvic inflammation
Cogwheel sign – cross-sectional view with thickened longitudinal folds of the uterine tubes associated with acute pelvic inflammation
Ovarian Torsion is a gynecologic emergency in which the ovary has twisted on its ligaments and blood supply. Rotation of the ovary leads to compression of arteries, veins, and lymphatics causing congestion, ovarian edema, and potentially infarction if untreated.
Acute pelvic or lower abdominal pain
Tenderness upon palpation with the transvaginal transducer
Ultrasound Findings of Ovarian Torsion:
Decreased power and/or color Doppler flow of veins and arteries*
Unilaterally enlarged/edematous ovary (>4 cm)
Possible midline position of ovary
String-of-Pearls sign – several peripheral follicles due to central lymphatic congestion
Whirlpool sign – wrapping of vessels around central axis of the pedicle shown with Doppler flow
Free pelvic fluid
*The sensitivity and specificity for ultrasound diagnosis of ovarian torsion are 72.1% and 99.6%, respectively (Rostamzadeh 2014). Because sonography is not 100% sensitive, Color Doppler ultrasound findings may be normal (blood flow maintained) despite the presence of ovarian torsion. This is due to the dual blood supply of the ovaries from both the ovarian and uterine arteries.
Therefore ovarian torsion is considered a clinical diagnosis and emergent gynecology consult should still be obtained if you have a high clinical suspicion despite a normal-appearing ultrasound.
Ovarian cysts are generally benign and show up on ultrasound in a variety of ways depending on their subtype. A few of the most common types are described below.
Corpus Luteum Cysts
Corpus Luteum Cysts are a normal part of the menstrual cycle and can enlarge further during pregnancy. These cysts are not usually associated with any significant symptoms unless they become hemorrhagic.
Ultrasound findings of Corpus Luteum Cysts:
Fluid-filled mass with thick, crenulated (shallowly scalloped, notched) wall
Internal echoes present
No internal vascularization
Possible extensive vascularization of corpus luteum wall on color Doppler – “Ring of Fire Sign” (this sign can also be seen in ectopic pregnancy)
Usually < 3 cm
Simple Ovarian Cysts
Simple cysts are fluid-filled sacs in the ovary thought to be caused by hormonal imbalances. The majority of simple cysts are benign but should be followed consistently to monitor for changes.
Exhibiting posterior acoustic enhancement (increased echogenicity posterior to the cyst)
Should be <5cm for premenopausal and <3cm for postmenopausal patients (if larger than followup may be warranted) – (Andreotti 2019)
Hemorrhagic cysts are usually seen in premenopausal women and are typically the result of bleeding into an ovarian cyst, follicle, or corpus luteum cyst.
Acute pelvic, flank, or abdominal pain
Ultrasound findings of Hemorrhagic Cysts:
Internal echoes with lacy/cobweb appearance (due to fibrin strands)
Clot with irregular borders and no Doppler flow*
Lack of internal vascularization
Posterior acoustic enhancement
*These characteristics can help differentiate between a hemorrhagic cyst and malignant nodule, which typically has internal vascular flow and clots with more rounded edges.
Hemorrhage cysts generally resolve spontaneously within 8 weeks. Postmenopausal women with cysts > 5 cm should be re-evaluated about 8 weeks after exam to ensure decreased cyst size.
The major complication associated with hemorrhagic cysts is rupture into the peritoneum resulting in symptoms similar to ectopic pregnancy (pain/tenderness on the affected side, nausea/vomiting, etc.).
Dermoid cysts (also called mature cystic teratomas) are the most common type of benign ovarian neoplasm. They are composed of at least 2 of the 3 fetal tissue layers (endoderm, mesoderm, ectoderm) and can therefore contain a variety of tissue types including thyroid tissue, cartilage, hair, skin, and bone.
Typically asymptomatic (often found incidentally or when associated with ovarian torsion)
Possible symptoms related to pressure on surrounding organs
Ultrasound Findings of Dermoid Cysts:
Due to the variety of tissue types that make up dermoid cysts, they can have several unique appearances on ultrasound imaging. The presence of two or more of the following findings is suggestive of dermoid cysts:
Diffuse echogenicity with posterior acoustic enhancement (increased echogenicity posterior to the cyst) – sebaceous tissue and hair; calcified bone or teeth
Echogenic mesh of lines and dots (“dot-dash sign”) due to the presence of hair.
Floating echoic fat globules
Fluid-fluid level – liquids of differing viscosities
Complications of dermoid cysts include conversion into a malignant tumor, ovarian torsion, hyperthyroidism (if ectopic germ cell tissue is of thyroid gland origin), and cystic rupture.
Polycystic Ovary Syndrome (PCOS)
Polycystic Ovary Syndrome (PCOS) is characterized by at least 2 out of 3 of the following criteria: