Pathology of the Uterus and Related Structures

Chapter 43: Pathology of the Uterus

Pathology of the Vagina and Cervix

• The vagina is anatomically situated anterior and caudal to the cervix, positioned between the urinary bladder and the rectum. Its normal length ranges from $7$ to $10 \text{ cm}$.

• Sonography: This imaging technique may be employed to characterize vaginal masses, such as Gartner’s duct cyst, which typically appear as anechoic or hypoechoic lesions with posterior enhancement, originating from embryological remnants of the Wolffian duct.

Anatomy Overview of the Vagina

Key Structures

• Anterior Fornix: The anterior recess of the vagina, anterior to the cervix.

• Urinary Bladder: Located anterior to the vagina.

• Urethra: Passes inferior to the bladder, anterior to the vagina.

• Posterior Fornix: The deepest recess of the vagina, posterior to the cervix, often accumulating fluid.

• Cervix: The lower, narrow part of the uterus, extending into the vagina.

• Rectum: Situated posterior to the vagina.

• Pouch of Douglas (Rectouterine Recess): The deepest point of the peritoneal cavity, located between the rectum and the posterior fornix of the vagina.

• Vagina: The muscular tube extending from the vulva to the cervix.

Congenital Abnormalities

• Imperforate Hymen: The most common congenital abnormality in the female genital tract, often identified at puberty. It results from incomplete canalization of the hymen, leading to an obstruction of menstrual outflow and impacted fluid flow within the reproductive tract.

• Potential outcomes of obstruction include:

  • Hydrometra: Fluid accumulation (serous or mucoid) in the uterus due to cervical or vaginal obstruction. The uterus appears distended with anechoic contents.

  • Hematometra: Blood accumulation in the uterus, typically seen in menstruating or postmenopausal women with obstruction. Sonographically, it appears as an enlarged uterus filled with echogenic material.

  • Pyometra: Pus accumulation in the uterus, usually secondary to infection behind an obstruction. The uterus is enlarged with heterogeneous, sometimes complex, fluid collections and potential gas.

Vaginal Masses and Carcinoma

• Solid masses in the vagina are rare, but when present, require thorough evaluation.

• While sonography is not typically used for primary diagnosis of vaginal carcinoma, it can assist in staging the tumor by assessing depth of invasion, involvement of adjacent structures (bladder or rectum), and lymph node metastasis.

• Common tumors include:

  • Vaginal Adenocarcinoma: Often associated with in-utero exposure to diethylstilbestrol (DES). It can manifest as a solid mass.

  • Rhabdomyosarcoma: A rare, aggressive tumor, primarily affecting infants and young children, often presenting as a botryoid (grape-like) mass in the vagina.

• Tumor characteristics:

  • Solid mass, potentially with necrotic areas appearing as central anechoic regions, indicating rapid growth exceeding blood supply.

  • Translabial scanning (or transperineal) may be utilized for assessment, particularly for distal vaginal lesions, providing high-resolution views of superficial structures.

Vaginal Cuff

• Definition: The vaginal cuff is a surgical remnant seen in patients post-hysterectomy, representing the apex of the vagina where the uterus was previously attached.

• Size considerations: The upper limit of a normal vaginal cuff is $2.1 \text{ cm}$ in length. Any larger cuff with well-defined masses or areas of high echogenicity, especially with increased vascularity on Doppler, raises suspicion for malignancy (e.g., recurrent carcinoma or metastasis), particularly in those with a history of gynecologic cancer.

• Nodular areas: May result from postirradiation fibrosis, which appears as heterogeneous, hyperechoic tissue with decreased vascularity due to scarring after radiation therapy.

Rectouterine Recess

• Located between the rectum and vagina, this is the most posterior and inferior reflection of the peritoneal cavity. It is often termed the Pouch of Douglas or posterior cul-de-sac.

• Common conditions associated with this area:

  • Intraperitoneal fluid collections can be detected with as little as $5 \text{ ml}$ of fluid via transvaginal sonography (TVS), making it a crucial site for assessing pelvic fluid.

• Normal Fluid Collections: Often observed in asymptomatic women across all menstrual phases, but typically maximally seen during ovulation (ruptured follicle) or just before menstruation (physiologic transudate).

• Pathological Fluid Collections:

  • Associated with conditions such as:

  • Ascites: Generalized abdominal fluid accumulation, often related to liver disease, heart failure, or malignancy (e.g., ovarian cancer).

  • Ruptured Ectopic Pregnancy: Hemorrhage into the cul-de-sac from a ruptured fallopian tube pregnancy, often presenting as complex fluid with internal echoes.

  • Hemorrhagic Cyst: Bleeding from an ovarian cyst into the peritoneum.

  • Infection-related pus (pelvic inflammatory disease): Thick, echogenic fluid often with septations, indicating an inflammatory process.

  • Pelvic abscesses and hematomas can also occur in this recess, appearing as complex, often loculated, fluid collections.

Cervical Anatomy

• Location: The cervix sits posterior to the bladder and between the lower uterine segment and the vaginal canal. It connects the uterine cavity to the vagina.

• Cervical canal anatomy: Extends from the internal os (where it joins the uterine cavity at the level of the isthmus) to the external os (which projects into the vaginal vault), providing a pathway for menstrual flow and sperm.

Cervical Sonography

• TVS of Cervix: Performed after the patient has emptied her bladder to optimize visualization and reduce acoustic shadowing from urine.

• Procedure: The transducer is inserted into the vagina with the patient in a supine position, knees flexed, and hips elevated on a pillow. This positioning straightens the vaginal canal and brings the cervix closer to the transducer for optimal imaging.

• Imaging Technique:

  • Slow withdrawal of the probe is necessary to capture full views of both the internal and external cervical os, ensuring the entire length of the cervical canal is evaluated. Views are taken in sagittal and coronal planes to assess for masses, lesions, or abnormalities in all dimensions.

Benign Conditions of the Cervix

Nabothian Cysts

• Description: Chronic inflammation of the cervix can lead to obstruction of the endocervical glands, resulting in retention cysts. These Nabothian cysts are benign, typically asymptomatic, and very common. Sonographically, they appear as rounded, anechoic or hypoechoic structures within the cervical stroma, often with posterior acoustic enhancement.

Cervical Polyps

• Clinical Presentation: These may cause irregular bleeding, postcoital bleeding, or discharge and arise from hyperplastic protrusions of endocervical or ectocervical epithelium, likely due to chronic inflammation. They are common in multiparous women.

  • Types: They may be pedunculated (attached by a stalk) or broad-based (sessile).

  • Visualization: Ultrasound detection can be varying; they often appear as echogenic masses within the endocervical canal, sometimes with a feeding vessel visualized on Color Doppler. Saline Infusion Sonohysterography (SIS) can improve visualization.

  • Incidence: Women in late middle age and perimenopausal women are more prone to develop polyps.

Cervical Myomas (Leiomyomas)

• Characteristics:

  • A small proportion ($1-8\%$) of leiomyomas occur in the cervix (the majority are in the uterine body). They are benign smooth muscle tumors.

  • Symptoms arise when masses enlarge, potentially causing bladder or bowel obstruction due to their location, urinary frequency, dyspareunia, or even difficult labor.

• Sonographic assistance: Imaging helps determine the stalk's location and thickness if pedunculated and their relationship to the bladder and rectum. Cervical myomas typically appear as hypoechoic, well-defined masses, often causing displacement of the cervical canal.

  • Use of sonohysterography can improve visualization to differentiate them from endometrial polyps or other intracavitary lesions.

Cervical Conditions and Stenosis

Cervical Stenosis

• Definition: An obstruction or narrowing of the cervical canal at either the internal os or external os, impeding the flow of substances (menstrual blood, mucus, sperm) through the cervix.

• Causes of Stenosis:

  • Radiation therapy: Scarring and fibrosis post-treatment.

  • Previous cone biopsy or LEEP (Loop Electrosurgical Excision Procedure): Procedures that remove cervical tissue, leading to scar formation.

  • Postmenopausal cervical atrophy: Thinning and inelasticity of cervical tissue due to estrogen deficiency.

  • Chronic infections: Can lead to inflammation and scarring.

  • Laser or cryosurgery: Destructive procedures causing fibrosis.

  • Cervical carcinoma: Tumor growth can physically obstruct the canal.

• Clinical Manifestations:

  • Menopausal women may be asymptomatic, despite potential engorgement of the uterus with secretions, resulting in hydrometra, pyometra, or hematometra when the obstruction prevents drainage.

  • Premenopausal symptoms may include:

  • Abnormal bleeding or secondary amenorrhea if uterine distension is significant.

  • Oligomenorrhea (infrequent periods).

  • Amenorrhea (absence of periods) due to outflow obstruction.

  • Cramping and Dysmenorrhea (painful menstruation) due to uterine distension.

  • Infertility due to impaired sperm transport or accumulation of intrauterine fluid.

Cervical Carcinoma

General Information

• Most Common Type: Squamous cell carcinoma, accounting for about $80\%$ of cases, often preceded by cervical dysplasias categorized into mild (CIN 1), moderate (CIN 2), or severe (CIN 3/Carcinoma in situ), almost exclusively caused by persistent Human Papillomavirus (HPV) infection.

• Definition: Carcinoma in situ refers to a lesion where the full thickness of the epithelium consists of undifferentiated neoplastic cells, but these cells have not yet invaded through the basement membrane.

Detection and Clinical Presentation

• The significance of Papanicolaou (Pap) Smears: Routine screening for cervical dysplasia and early carcinoma has dramatically reduced the incidence and mortality of invasive cervical cancer by allowing early detection of asymptomatic lesions.

• Advanced cervical cancer often manifests clinically with symptoms such as abnormal vaginal bleeding (especially postcoital), foul-smelling discharge, pelvic pain, or sciatic pain if nerve involvement is present.

Sonographic Findings

• Sonography is generally used for staging rather than primary diagnosis. Possible indicators in advanced cases include:

  • Retrovesical mass: An ill-defined, solid, hypoechoic mass infiltrating the cervix and extending posteriorly towards the rectum or anteriorly towards the bladder.

  • Obstruction of ureters: Hydronephrosis may be seen secondary to tumor compression of the ureters, indicating advanced disease.

  • Invasion into bladder tissue: Irregularity or thickening of the bladder wall adjacent to the cervical tumor.

Translabial or Transperineal Sonography

• Procedures involve:

  • Employing a 5.0- to 7.5-MHz sector or curvilinear transducer, covered with a sterile probe cover and gel, applied to the vestibule of the vagina (translabial) or the perineum (transperineal) in the sagittal plane. This technique is excellent for visualizing the cervix, urethra, and pelvic floor muscles.

  • Partial bladder filling may improve visualization of the cervical area and acts as an acoustic window, pushing bowel loops out of the field of view.

  • Proper patient positioning (e.g., lithotomy position with hips slightly elevated) facilitates anatomical identification and reduces air interference, which can obscure superficial structures.

Pathology of the Uterus

Anatomical Context

• The uterus is located in the true pelvis, positioned between the urinary bladder anteriorly and the rectosigmoid colon posteriorly. It is a hollow, pear-shaped muscular organ.

• Changes in uterine position may occur due to bladder and rectal distension, which can displace the uterus and potentially mimic masses or make accurate assessment difficult during physical exams or routine imaging.

Uterine Flexion and Version

• Flexion: Refers to the angle of the uterine body in relation to the cervix. It describes the bend in the uterus itself.

• Version: Describes the angle of the cervix in relation to the vagina. It describes the overall tilt of the uterus within the pelvis.

• Normal position: Anteverted (cervix points inferiorly and anteriorly, forming a $90^ ext{o}$ angle with the vagina) and anteflexed (uterine fundus bends anteriorly over the cervix). Variations may occur, such as retroflexed (fundus bends posteriorly) or retroverted (cervix points superiorly and posteriorly) positions, which are usually asymptomatic but can sometimes cause dyspareunia.

Uterine Variations

• Uterine shape variations are congenital anomalies resulting from abnormal fusion of the Müllerian ducts during fetal development. They include:

  • Bicornuate Uterus: Characterized by two uterine horns that are fused at the lower uterine segment and cervix, but separated at the fundus, giving it a heart shape. It is associated with increased risk of miscarriage and preterm labor.

  • Didelphic Uterus: A complete duplication of the uterus, cervix, and often the vagina, resulting from a complete failure of Müllerian duct fusion. Each uterus usually has its own fallopian tube and ovary.

Differential Considerations for the Uterus

Conditions Causing Uterine Enlargement

• Pregnancy: Physiological enlargement due to a growing fetus.

• Postpartum: Enlargement (subinvolution) due to incomplete return of the uterus to its non-pregnant size.

• Leiomyoma (myoma): Benign muscular tumors that can significantly increase uterine size.

• Adenomyosis: Endometrial tissue within the myometrium causing diffuse uterine enlargement and thickening of the myometrium.

• Bicornuate or Didelphic Uterus: Congenital anomalies where the uterus appears larger due to duplicated or abnormally shaped structures.

Tumors

• Leiomyoma: The most common gynecologic tumors, occurring in $20-30\%$ of women over $30$ years, with a higher prevalence in African American women. These are benign smooth muscle tumors.

• Carcinoma (Uterine Cancer): Endometrial carcinoma can cause uterine enlargement, especially in advanced stages, or focal masses.

Endometrial Changes

• Thickened Endometrium: A common sonographic finding that warrants further investigation. Causes include:

  • Early intrauterine pregnancy: Gestational sac and decidual reaction.

  • Endometrial hyperplasia: Overgrowth of endometrial tissue due to prolonged estrogen exposure.

  • Retained products of conception or incomplete abortion: Tissue remaining in the uterus after pregnancy or miscarriage.

  • Trophoblastic disease: Abnormal proliferation of trophoblastic tissue (e.g., hydatidiform mole).

  • Endometritis: Inflammation of the endometrium.

  • Adhesions (Synechiae): Scar tissue within the endometrial cavity.

  • Polyps: Benign growths of endometrial tissue.

  • Inflammatory disease: General inflammation affecting the endometrium.

  • Endometrial carcinoma: Malignant growth of the endometrium.

Endometrial Fluid Presence

• Causes may include:

  • Endometritis or Pyometra: Inflammation or pus collection.

  • Retained products of conception: Can be associated with blood or serous fluid.

  • Pelvic Inflammatory Disease (PID): Can lead to fluid collection if inflammation spreads to the endometrium.

  • Cervical obstruction: Preventing drainage of normal secretions, blood, or pus, leading to hydrometra, hematometra, or pyometra.

Endometrial Shadowing

• Possible causes: Acoustic shadowing behind a hyperechoic structure within the endometrium.

  • Gas (abscess): Can produce