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Pelvic Ultrasound Vocabulary: PID, Endometriosis, Infertility, and Related Structures

Anatomy of the adnexa: ovaries, fallopian tubes, and supporting structures

  • Fallopian tubes contain multiple named parts from proximal (uterus) to distal (ovary):
    • Interstitium: the portion that penetrates the uterine wall and connects to the cornu.
    • Isthmus: the narrow portion between the uterus and the ampulla.
    • Ampulla: the widened segment where fertilization typically occurs.
    • Infundibulum: the funnel-shaped, widest opening that flares toward the ovary; fimbriae are finger-like projections at the end that help capture the ovulated oocyte.
    • Fimbriae: finger-like projections that help guide the ovulated egg into the tube.
  • Mesentery and peritoneal folds:
    • Peritoneum folds create the mesosalpinx around the fallopian tube.
  • The ovaries and adnexa are contained by ligaments and pelvic vessels (iliacs) that serve as imaging landmarks to locate the adnexa.
    • Lateral landmarks: iliac vessels.
    • Medial landmark: uterus.
  • Orientation tips when imaging to memorize the order (proximal to distal):
    • A common mnemonic to remember order: eyes and incredible eyes and eyes incredible at finding ovaries. (Aim to memorize the proximal-to-distal sequence: interstitium → isthmus → ampulla → infundibulum; fimbriae attach near the infundibulum.)
    • Use your own personalized cue if you prefer a different order reminder.

Adnexa imaging approach and landmarks

  • In transverse view: you should see the iliac vessels laterally and the uterus medially; the left adnexa sits near the left iliac vessels and the uterus is on the right side of the screen (and vice versa for right adnexa).
  • In sagittal view: scan laterally toward the iliac vessels, then move toward the uterine fundus.
  • Objective: identify adnexal structures, assess for fluid, masses, and signs of inflammation or infection; document location and size for radiologist interpretation.

Pelvic inflammatory disease (PID): overview

  • Most common pathology in the adnexa: PID, typically caused by sexually transmitted diseases; other causes include:
    • Ruptured appendix or other causes of peritonitis (less common).
    • Ascending infection from retained products of conception or surgical intervention.
  • In PID, infection and inflammation can spread from the endometrium to the fallopian tubes and surrounding structures, creating a spectrum of disease.
  • Pathophysiology examples and relationships:
    • Endometritis: infection/inflammation of the endometrium (lining of the uterus).
    • Salpingitis: inflammation of the Fallopian tubes.
    • Hydrosalpinx: distended, fluid-filled Fallopian tubes due to obstruction and inflammation.
    • Pyosalpinx: pus-filled Fallopian tubes due to infection.
    • Periovarian inflammation: inflammation of the tissues around the ovary and adjacent peritoneum.
    • Tubo-ovarian (TO) complex: inflamed tubes and ovaries that may be adherent together.
  • Etiologies and risk factors discussed:
    • Early sexual activity and multiple sexual partners.
    • History of STDs; prior PID increases risk.
    • IUD use associated with higher PID risk due to foreign-body introduction and potential ascent via the string.
    • Douching or other vaginal/uterine interventions that introduce bacteria.
    • Post-procedure infections (e.g., after abortion, D&C) can introduce bacteria.
  • Clinical presentation:
    • Pelvic pain and tenderness; severe pain with transvaginal ultrasound ( chandelier sign ) indicating cervical motion or vaginal examination pain.
    • Pelvic pain with dyspareunia; fever; vaginal discharge; irregular bleeding; possible asymptomatic cases.
  • Laboratory findings:
    • Elevated white blood cell count (WBC).
    • Possible evidence of concurrent chlamydia infection.

Ultrasound and imaging signs in PID

  • General sonographic appearance of PID:
    • Fluid in the cul-de-sacs (anterior and posterior) due to inflammation.
    • Enlarged, inflamed ovaries; hyperemic appearance on color Doppler (increased blood flow).
    • Thickened endometrium and thickened tubal walls.
    • Fluid around the uterus and ovaries; complex collections may be present.
  • Specific signs and signs to recognize:
    • Lobster claw sign: when the uterus, ovary, and a dilated tube form a claw-like appearance on ultrasound; suggests tubal involvement with fluid and inflammation around the tube and ovary.
    • Ring-down artifact (dirty shadowing): due to air in infected tissue; appears when air is present from bacterial infection; can obscure thickness measurement.
    • Three-line sign (in liver): peritonitis or peritoneal inflammation can cause a characteristic thickened diaphragmatic line seen on ultrasound/CT (perihepatic inflammation).
  • Color Doppler findings:
    • Hyperemia of inflamed tissues; increased vascularity around endometrium, ovaries, and adnexa.
  • Beak sign (for hydrosalpinx/ectopic tube):
    • Beak-shaped tip where the tube attaches to the uterus; helps differentiate a dilated tube from a simple pelvic fluid collection.
  • Pelvic fluid collections:
    • Hydrosalpinx: anechoic or echo-free fluid within a dilated tube; walls become thin with time; may appear bilaterally.
    • Pyosalpinx: complex fluid with internal echoes representing pus; tubes may be dilated and tortuous.
  • TO (tubo-ovarian) complex and TO abscess:
    • TO complex: inflamed fallopian tube and ovary with adherence; may be difficult to separate surgically.
    • TO abscess: severe infection with pus, significant adhesions, and potential extension into the peritoneum.
  • Endometritis signs:
    • Thick endometrium with intrauterine content (retained products of conception after birth or abortion).
    • On ultrasound, the endometrium may appear thickened and heterogeneous; ring-down artifact may obscure measurement if air is present.
  • Differential imaging considerations:
    • Distinguishing PID from a dermoid (mature cystic teratoma): look for teeth, hair, and other tissues in a dermoid; PID tends to be hyperemic and thickened with fluid collections, rather than a solid teratoma appearance.
    • Endometritis vs. other causes of endometrial thickening: correlate with history (postpartum, miscarriage, retained products) and use Doppler to assess vascularity.

Endometritis and related inflammatory conditions

  • Endometritis: PID limited to the endometrium; may occur after childbirth, abortion, or intrauterine instrumentation.
  • Retained products of conception: can cause endometritis; ultrasound shows thickened, possibly echogenic endometrium with debris; may require D&C.
  • Dilation and curettage (D&C, also noted as DNC in some contexts):
    • Procedure to dilate the cervix and curettage endometrium to remove retained tissue; used postpartum or postabortion when retained products are suspected.
    • Also used to treat thick endometrium and evaluate for polyps or other pathology.
    • Interventions such as D&C can introduce infection risk if performed in the setting of PID.

Endometriosis and related ovarian pathology

  • Endometriosis: ectopic endometrial tissue outside the uterine cavity; functional tissue that cycles with hormones and bleeds, causing pain and inflammation.
  • Endometrioma (chocolate cyst): focal endometriosis in the ovary; referred to as chocolate cyst or endometrioma.
  • Diffuse vs focal disease:
    • Diffuse endometriosis can involve multiple pelvic organs.
    • Focal endometriosis on the ovary is termed an endometrioma or chocolate cyst.
  • Symptoms often include: dysmenorrhea (painful periods), dyspareunia (pain with intercourse), dysuria (painful urination), and dyschezia (painful defecation). These are described as the four D's of endometriosis.
  • Impact on fertility:
    • Endometriosis can contribute to infertility through inflammatory changes, adhesion formation, and distortion of pelvic anatomy.
  • Imaging considerations:
    • Ultrasound can detect endometriomas but is limited for non-ovarian pelvic disease.
    • MRI is often better for diagnosing endometriosis outside the ovaries and for mapping extent.
  • Pathophysiology concept: endometriosis may arise via retrograde menstruation or endometrial seeding (e.g., after procedures like D&C) and implant in peritoneal surfaces.
  • Adenomyosis (differential in uterus): thickened myometrium with bulky uterus; MRI is more sensitive for detection than ultrasound in many cases.

Pelvic Congestion Syndrome (PCS)

  • Pathophysiology: chronic retrograde venous flow due to incompetent valves in the ovarian veins leading to pelvic pain.
  • Predominant vein affected: left ovarian vein, because it drains into the left renal vein (longer path) vs. the right side draining more directly into the IVC.
  • Clinical presentation: chronic pelvic pain that worsens with standing or bearing down or with Valsalva maneuver.
  • Imaging approach with Doppler:
    • Use color Doppler to detect venous reflux and dilation.
    • Measure vein diameter in transverse view; typical values around 5-6\ \text{mm} for affected veins; larger in males than females in some contexts.
    • Perform dual-screen: resting (left) vs. Valsalva (right) to demonstrate reflux.
  • Valsalva maneuver: hold breath or bear down to increase intraabdominal pressure; a positive test shows reflux on color Doppler.
  • Visual signs: serpiginous (snake-like) venous structures around the uterus and pelvis, which increase in color with Valsalva.

Falls under gynecologic oncology: fallopian tube carcinoma

  • Fallopian tube carcinoma is typically adenocarcinoma and occurs in postmenopausal women.
  • Imaging finding: a complex, sausage-like tubular mass in the tube region; associated with advanced age and pelvic pain.

Other pelvic masses and differential considerations in ultrasound

  • Appendicitis can present as pelvic pain and may be mistaken for ovarian/adnexal pathology:
    • Thick-walled appendix with a target sign on imaging; consideration given to differential when right lower quadrant pain is present.
  • Diverticulitis and diverticular abscesses can present with pelvic or abdominal pain and may be encountered in ultrasound.
  • Urinary system findings:
    • Hydronephrosis: dilation of the renal pelvis and calyces due to downstream obstruction.
    • Ureteral stones: echogenic focus with posterior acoustic shadowing; can cause acute flank or groin pain.
    • Diverticula or diverticular disease of the bladder wall (diverticulum) and bladder pathology (e.g., cystitis, bladder cancer).
  • Pelvic kidneys and ectopic pelvic anatomy:
    • Some individuals have kidneys that fail to migrate and remain in the pelvis; may have ureteral kinks causing hydronephrosis.
  • Bladder wall pathology:
    • Cystitis: irregular, thickened bladder wall with multiple signs of inflammation.
    • Diverticulum: outpouching of the bladder wall; a small opening can be seen as a diverticular mouth.
  • Practical imaging approach for masses:
    • Always document location, size, relationship to uterus, ovary, and the blood supply.
    • Try to identify the source (uterus vs. ovary vs. bladder vs. bowel) to provide radiologists with actionable information.

Interventional ultrasound and procedures

  • Interventional ultrasound covers procedures performed in conjunction with pelvic imaging:
    • D&C (dilation and curettage) for retained products or endometrial sampling.
    • Cyst aspiration or drainage procedures.
    • IUD placement or evaluation.
    • Transrectal or transvaginal drainage under ultrasound guidance.
    • Biopsy procedures guided by ultrasound.
  • The ultrasound role: guiding, documenting, and ensuring safe hepatic, pelvic, or adnexal interventions.

Infertility and fertility treatments: ultrasound’s role

  • Infertility: approximately 40% female factors and 40% male factors; ultrasound helps identify female-factor contributors.
  • Common female-factor issues assessed by ultrasound:
    • Ovulation status and ovulatory function (assessment of ovaries and follicular activity).
    • Tubal patency via indirect signs (adhesions, hydro-salpinx) and follicle development.
    • Endometrial thickness and phase (secretory vs proliferative) to assess readiness for implantation.
    • Uterine factors such as fibroids and scar tissue that could impede implantation.
    • Adhesions or scarring that may block the fallopian tubes or alter tubal transport.
  • Follicle counting and measurement:
    • Transvaginal ultrasound is used to count and measure ovarian follicles during stimulation therapy.
    • Typical follicle size targets for harvest in IVF cycles: between 18\text{ mm} and 24\text{ mm} in diameter.
    • During monitoring, follicles are counted and measured across each ovary in a systematic order (superior to inferior, lateral to medial).
  • Doppler assessment:
    • Doppler evaluation of ovarian blood flow to confirm adequate perfusion during stimulation and before retrieval.
  • Pharmacologic agents involved in fertility treatments:
    • Clomiphene citrate (Clomid) for ovulation induction.
    • Metformin (glucose regulation) may aid ovulation in PCOS or insulin resistance; discuss specific mechanism as part of care.
    • Synthetic human chorionic gonadotropin (HCG, e.g., Pregnyl) to trigger ovulation.
  • Assisted reproductive technologies (ART):
    • IVF (in vitro fertilization): ovarian stimulation, oocyte retrieval, fertilization in vitro, embryo culture, and transfer of embryos into the uterus.
    • ZIFT (zygote intrafallopian transfer): fertilized zygote is implanted into the fallopian tube.
    • GIFT (gamete intrafallopian transfer): eggs and sperm are placed together into the fallopian tube; fertilization occurs in the tube.
    • IUI (intrauterine insemination): prepared sperm is inserted directly into the uterus to improve fertilization chances when male factor is present.
  • Complications of fertility treatments: ovarian hyperstimulation syndrome (OHSS)
    • OHSS features: numerous large follicles on both ovaries (bilateral); ascites can occur; fluid shifts can be significant.
    • OHSS can be severe and, in some cases, life-threatening; reported risk includes mortality in a subset of cases and an increased rate of multiple gestations.
    • Clinical risk factors include high estrogen levels and rapid follicular growth; management requires close monitoring.

Case-based considerations described in the lecture

  • Postpartum case: 31-year-old female, three days postpartum with fever and severe pelvic pain; ultrasound with color Doppler shows hyperemic flow; thickness difficult to measure due to ring-down artifact from air; probable diagnosis: endometritis due to retained products of conception.
  • A history of PID in the past with pyosalpinx noted on prior imaging but currently fertility concerns: incidental finding of hydrosalpinx on ultrasound without current symptoms; likely due to scarring from prior PID; this fluid-filled, dilated tube can impair fertility.

Practical takeaways for ultrasound practice

  • In PID, look for: cul-de-sac fluid, thickened endometrium, hyperemic adnexa, and tubal dilation or tortuosity with beak sign.
  • Distinguish PID from other adnexal pathology using history, ultrasound features, and Doppler signals (hyperemia favors inflammatory/infectious processes).
  • Recognize important ultrasound signs:
    • Lobster claw sign for PID-related adnexal involvement.
    • Beak sign for tubal attachment and hydrosalpinx diagnosis.
    • Ring-down artifacts indicating air from infection; may obscure thickness measurements.
  • Document thoroughly: location, size, relation to uterus/ovaries, and vascularity to aid radiologists and clinicians.
  • Understand the broader clinical context: infection risk with interventions (IUD insertion, D&C, surgeries), post-partum infections, and the potential impact on fertility.
  • Be aware of the limits of ultrasound: MRI may be superior for certain pelvic pathologies (e.g., endometriosis extent) while ultrasound remains essential for dynamic assessment, guided procedures, and initial evaluation.

Quick reference: key measurements and terms to remember

  • Endometrial thickness in the secretory phase: about 14\ \text{mm} (reference given in lecture).
  • Ovarian follicle size for harvesting in IVF: 18-24\ \text{mm}.
  • Ovarian vein dilation in pelvic congestion syndrome: typically around 5-6\ \text{mm} when abnormal.
  • Hydrosalpinx: dilated, fluid-filled tube; often bilateral in PID-related cases.
  • Pyosalpinx: pus-filled dilated tube with complex fluid.
  • Ring-down artifact: acoustic artifact due to air in infected tissue; compromises thickness measurement.

Memory aids and quick cues

  • Proximal-to-distal tubal anatomy cue: interstitium → isthmus → ampulla → infundibulum; fimbriae near infundibulum.
  • PID clues: lobster claw sign, hyperemic tissue on color Doppler, and peritoneal involvement in advanced disease.
  • PCS cue: test with Valsalva to demonstrate venous reflux on color Doppler; measure veins for dilation.
  • Endometriosis cues: chocolate cyst (endometrioma) and endometriosis-associated pain (the 4 D’s).
  • IF you suspect PID after procedures (D&C, abortion, IUD): high index of suspicion for infection due to introduction of bacteria.

Summary: key concepts to know for exams

  • Anatomy and function of Fallopian tubes and the adnexa, including the four tubal segments and supporting structures.
  • PID pathway from endometritis to salpingitis to hydrosalpinx/pyosalpinx and tubo-ovarian complex, and its consequences for fertility and pregnancy (including ectopic risk).
  • Important ultrasound findings and signs (lobster claw, beak sign, ring-down artifact, hyperemia, cul-de-sac fluid, thickened endometrium).
  • Endometriosis and endometrioma: clinical signs, fertility impact, and imaging nuances (MRI advantages).
  • Pelvic Congestion Syndrome: venous dilation and reflux with Valsalva; left-sided predominance.
  • Other pelvic masses and differential considerations (appendicitis, diverticulitis, diverticulum, bladder pathology, hydronephrosis, pelvic kidneys).
  • Interventional ultrasound: various procedures that involve pelvic organs and their implications for imaging.
  • Fertility treatments and ultrasound roles: follicle counting, endometrial assessment, embryo/fertilization strategies (IVF, ZIFT, GIFT, IUI), OHSS risks.
  • The importance of precise documentation for radiologists and clinicians to guide management and fertility planning.