Female External Genitalia Anatomy

External Genitalia (Vulva) Parts

• Mons pubis (mons veneris): A pad of fat on the symphysis pubis covered by hairy skin (pubic hair).
• Labia majora: Two large, thick skin folds covered by hairs, except on the inner aspects
• Labia majora is homologous to the male scrotum
• Labia minora: Two folds of smooth, non-hairy skin that lie medial to the labia majora and are smaller in size
• The labia minora is homologous to the penile urethra in males
• Labia minora are very vascular, becoming turgid and congested during sexual excitement.
• The labia minora divides anteriorly to form the prepuce above the glans of the clitoris, and the frenulum below the glans of the clitoris
• The labia minora unite posteriorly to form the fourchette.

Bartholin's Glands (Greater Vestibular Glands)

• Modified racemose sebaceous glands that secrete sebaceous material for lubrication during sexual excitement
• Located in the posterior 1/3 of the labia majora
• Each gland has a 2 cm long duct that passes the hymen and labia minora to open into the vagina
• The duct openings are not seen unless inflamed or obstructed

Clitoris

• A highly sensitive erectile organ.
• Homologous to the male penis, but does not contain the urethra.
• Formed of a body, made of two crura cavernosa and a glans, covered by a prepuce from above and a frenulum from below

External Urethral Meatus

• A triangular slit located below the clitoris
• Can be seen by separating the labia minora
• The normal female urethral length is 3-4 cm and is totally related to the anterior vaginal wall.

External Vaginal Orifice

• The lower vaginal end, closed by the hymen in virgins.

Hymen

• A double-layered mucous membrane that closes the lower vaginal orifice in a virgin
• Has an opening for menstrual blood to pass, which can be single, bi-partite, cribriform, annular, or crescentic

Vestibule

• The closed space between the two labia minora.
• Structures opening into it: the external urethral meatus, the external vaginal orifice, and Bartholin's glands

Vestibular Bulbs

• Two oblong erectile tissues, lying on each side of the vaginal orifice, that are visible when strained

Perineum

• The area lying between the vaginal orifice anteriorly and the anus posteriorly, and covers the perineal body
• Formed of perineal skin, subcutaneous tissues, and perineal muscles (superficial and deep transverse perinii, bulbospongiosus, and deep fibers of levator ani)
• Ischiocavernosus muscles do not share in the perineal body.

Muscles Attaching to the Perineal Body

• Transverse Perineal (superficial and deep)
• Bulbospongiosus
• External anal sphincter
• Pubococcygeus

Fascia Attaching to the Perineal Body

• Colles' fascia
• Perineal membrane
• Deep investing fascia

Blood and Nerve Supply of the Vulva

• Arterial supply: Internal and external pudendal arteries
• Venous drainage: Corresponding to the arteries
• Lymphatic drainage: To the superficial and deep femoral and inguinal lymph nodes
• Nerve supply: Pudendal nerve (S2, S3, S4 motor and sensory), ilioinguinal nerve, genital branch of the genitofemoral nerve, and posterior cutaneous nerve of the thigh

Internal Genital Organs

• Include the vagina, uterus, fallopian tubes, and ovaries.

Vagina

• A fibromuscular organ extending from the vulva to the uterus.
• Shaped like an inverted flask (the upper end is twice as capacious as the lower end)
• The lower end is closed by the hymen in virgins
• The upper end is blind and is called the vaginal vault
• The vaginal vault is pierced by the cervix
• There are four pouches or fornices: one anterior, one posterior, and two lateral.
• The anterior wall is 7-9 cm long, the posterior wall is 9-11 cm long

Vagina Histology

• Mucosa: Stratified squamous non-keratinized epithelium with no glands, thrown into folds called vaginal rugae
• The rugae harbor Doderlein's bacilli (lactobacilli), which are responsible for vaginal acidity (pH 4.5) by breaking down glycogen and releasing lactic acid
• Estrogen stimulates the action of these bacilli
• The vagina is kept moist by cervical secretions and exudates from the epithelium
• The anterior vaginal wall shows four depressions or sulci in the mucosa
• Tunica propria: A thin layer of elastic vascular connective tissues
• Muscle layer: A thin layer of musculo-facial envelope that surrounds the vagina and is continuous above with that of the cervix and uterus
• Adventitia (paracolpos): Outer fibrous tissue layer of the vagina, which is excessive and allows high dispensability of the vagina

Blood Supply of the Vagina

• Vaginal artery: The main arterial supply, arising from the internal iliac or uterine artery, supplies mainly the upper vagina
• Branches from the middle rectal, inferior rectal, and vesical arteries supply mainly the lower vagina
• Venous drainage: Accompanies the corresponding arteries and drains into the internal iliac vein.

Uterus (The Womb)

• An inverted pear-shaped organ measuring 1x2x3 inches and weighing about 50-80 grams
• Lies centrally in the pelvis in an anteverted anteflexed (AVF) position
• Anteversion: Forward angulation with the longitudinal axis of the cervix making a right angle ("90°") with the axis of the vagina
• Anteflexion: Forward angulation with the longitudinal axis of the cervix making an obtuse angle (150-160°) with the longitudinal axis of the fundus and body
• Internal os lies at the level of the upper border of symphysis pubis in the standing position, while the external os lies at the level of the ischial spines.

Uterus Anatomical Divisions

• Uterine body (corpus uteri): The main part of the uterus, lying above the level of the internal os
• Fundus: The part of the body above the insertion of the fallopian tubes is dom-shaped ("convex")
• Cornu: The area of insertion of each fallopian tube into the body, with the fallopian tube attached laterally, the ovarian ligament posteroinferiorly, and the round ligament anteroinferiorly.

Uterus Histology

• The uterine body is formed of three layers:
  • Endometrium: Consisting of tubular or columnar epithelium and simple tubular glands resting on the myometrium without a basement membrane, the hormone-dependent layer differentiating into the superficial compact layer, middle spongy layer (shed during menstruation), and basal compact layer (for regeneration)
  • Myometrium (muscle layer): Consisting of inner circular, outer longitudinal, and intermediate interlacing fibers.
    • The arrangement of the intermediate layers is important as they surround blood vessels
    • By contraction of the muscle, blood vessels are compressed, controlling blood flow and blood loss during menstruation and the third stage of labor
  • Perimetrium: The peritoneum covering the uterus anteriorly and posteriorly, reflecting on the bladder to form the uterovesical pouch and on the rectum to form the Douglas pouch (= cul de sac).
    • The two layers meet to form the broad ligament.

Isthmus Uteri

• The lowest and narrowest part of the uterus just above the cervix, lying between the anatomical internal os (constriction where the body joins the cervix) and the histological internal os (the area of transition of endometrial lining into cervical one) It measures 4-5 mm, seen by microscopy
• It’s the lower uterine segment during pregnancy & labor.
• Progesterone causes contraction
• Estrogen causes relaxation

Cervix

• The lower most part of the uterus measuring about one inch (2.5 cm), divided by the piercing of the vaginal vault into the supra-vaginal part and the Portio vaginalis
• Consists of a mucous membrane, gradually changing from endometrial epithelium to low columnar epithelium at the internal os and modified squamous epithelium at the external os
• The area of change at the external os is called the transformation zone
• The muscle layer consists of outer longitudinal and inner circular muscle layers only, and the adventitia is a layer of fibrous tissues.

Blood Supply of Uterus

• Uterine artery: Arises from the anterior division of the internal iliac artery as one of its terminal branches, running forward and inwards in the base of the broad ligament
• Crosses above the ureter 1.5 cm lateral to the supravaginal cervix
• Reaches the uterus at the level of the internal cervical os then ascends in a tortuous way alongside the uterus within the two leaves of the broad ligament to supply the uterus at all levels
• Terminates by anastomosing with the ovarian artery at the distal 1/3 of the fallopian tube to form a continuous arterial arch.
• Branches: The main uterine branch divides into anterior and posterior arteries which are disposed circumferentially in the myometrium and anastomose with those from the opposite side (the uterus is therefore least vascular in the middle line.)
  • A descending cervical branch, forming a circular artery of the cervix, gives the anterior and posterior azygos arteries to the vagina
  • A vaginal artery branch may arise separately from the uterine artery
  • Other branches to the ureter, bladder, and upper vagina
  • Branches to fallopian tube and ovary
• Ovarian artery: Arises from the aorta.

Uterus Venous Drainage

• Uterine vein, pampiniform plexus of veins, internal iliac veins.
• Ovarian veins: Right to IVC, Left to Lt renal vein.

Ligamentary Supports of the Uterus

• The cardinal ligaments are condensations of pelvic fascia including:
  • Pubocervical ligaments: A pair of ligaments passing from the front of the cervix and upper vagina to the back of the symphysis pubis, and are divided into pubovesical and vesicocervical ligaments due to the presence of the bladder and urethra in its course.
  • Mackenrodt's ligaments: The main cardinal ligaments passing as a fan shape from the lateral aspect of the cervix and upper vagina to be inserted into the lateral pelvic wall, related laterally to the uterine artery and the ureter, and representing the largest and strongest fascial support of the genital tract.
  • Uterosacral ligaments: Passing from the back of the cervix and upper vagina to the 3rd piece of the sacrum, their tone is responsible for the anteversion position and are the most developed supportive ligament of the uterus.

Accessory Ligaments of the Uterus

• Broad ligament: A double-sheeted peritoneal layer arising from the side wall of the uterus due to the meeting of the ant. and post. peritoneal covering It passes laterally to be inserted into the lateral pelvic wall by a tapered end called the "infundibulo-pelvic ligament"
• Contents: Round, Ovarian and Mackenroadt's ligaments, fallopian tubes above and terminal part of the ureter behind its lowermost end, uterine and ovarian vessels and their anastomosis on lower surface of the tube, ovarian and paracervical nerves, lymphatic drainage of the uterus and along the round ligament, and vestigeal remnants (Gartner's duct, Epoophron, Paroophron and Hydatid cyst of Morgagni).

Fallopian Tubes

• Two long tortuous tubes arising from the cornu of the uterus and pass in the free upper end of the broad ligament, each measuring about 10-12 cm
• Divided into four parts "from in out": the interstitial part (inserted in the uterine wall), isthmus (the narrowest part lying adjacent to the uterus), ampulla (the widest and longest part, 5-6 cm, lying lateral to the isthmus), and infundibulum (the fimbriated outer end, with a long fimbria directed towards the ovary called the fimbria ovariaca responsible for picking up the ovum)
• Histology: –Endosalpinix: An inner layer of columnar epithelium that shows ciliated type (move its cilia towards the uterine cavity), Goblet like cells (secretory cells), and Peg-shaped cells (act as reserve cells).
  • Muscle layer: outer longitudinal and inner circular.
  • Outer serous layer: The peritoneal covering of the tube.

Blood Supply Fallopian Tubes

• Arterial: Ovarian artery and uterine artery.
• Venous: Ovarian vein, Uterine vein and pampiniform plexus of veins.

Surgical Importance Fallopian Tubes

• It has dual blood supply, so gangrene cannot occur.
• Ectopic pregnancy commonly occurs in the fallopian tube.
• Tubal causes are the commonest causes of female infertility.
• The site of some procedures of ART like G.I.F.T (gamete intrafallopian transfer), Z.I.F.T. (zygote intrafallopian transfer).
• Tubal ligation is considered as a method of contraception.

Ovaries

• Definition: The primary sex organ in the female
• Site: Retroperitoneal structure lying in the ovarian fossa on the lateral pelvic wall
• Size: Measures 1 x 2 x 3 cm
• Weight: About 5-10 grams
• Color: Dull white
• Surface: Smooth surface in young females, becoming corrugated due to cyclic ovarian trauma after each ovulation in adults.
• Formed of hilum, cortex and medulla – Hilum: The part on the ventral aspect via which the blood vessels, nerves and lymphatics pass to and from the ovary – Cortex: The active outer part of the ovary as it contains the ovarian follicles – Medulla: The central core formed mainly of fibrous tissues.
• Histology, from out to in: Germinal epithelium, tunica albuginea, cortex and medulla

Ligaments of the Ovary

• Mesovarium: Part of the broad ligament suspending the ovary to its back.
• Ovarian ligament: Fibrous ligament that attaches it to the back of the uterus.
• Infundibulo-pelvic ligament: The most lateral tapering part of the broad ligament, attaching the ovary to the lateral pelvic wall.

Blood Supply of the Ovaries

• Arterial: Ovarian artery directly from the aorta, with some branches of the uterine artery.
• Venous: Right ovarian vein passes to the IVC, while the left ovarian vein passes to the left renal
• Some venous drainage passes with the uterine vein to pampiniform plexus then to the internal iliac

Supports of the Uterus, Vagina and Pelvic Floor

• The position of the uterus and vagina in the pelvis is maintained by the following supports:
  • Upper supports: AVF position, round and broad ligaments
  • Middle supports: cardinal ligaments
  • Lower supports: Levator ani and coccygeus muscles, urogenital diaphragm, and the perineal body.
• Levator ani parts includes pubococcygeus, iliococcygeus and ischio-coccygeus.
• Pubococcygeus (the main part), origin from the back of S, pubis, from part of the white line
• Iliococcygeus origin from white line of obturator facia
• Ischio-coccygeus origin from ischial spine
• N. supply supplied from sacral 2, 3, 4 nerves.

Pelvic Floor

• Formed of pelvic peritoneum, pelvic cellular tissues (pelvic fascia), levator ani muscles, perineal muscles, and subcutaneous fat and skin.

Pelvic Ureter

• Definition: A narrow muscular tube that is 25 cm long and lies retroperitoneal in its whole course
• Enters the pelvis by crossing over the common iliac vessels at the site of its bifurcation
• Desends along the front of the internal iliac vessels till the level of ischial spine
• Turns inwards and forwards in the base of the broad ligament below and at right angle with the uterine artery ("water under bridge"); 1.5 cm lateral to the supra-vaginal cervix and above the vaginal vault
• Enters the ureteric canal, which lies just above the lateral vaginal fornix
• Passes medially to enter the trigone of the bladder
• Histology: Formed of muscular layer lined by transitional epithelium
• Blood supply: Uterine, vaginal and inferior vesical arteries OR a separate special branch from internal iliac called Michael's artery.

Points of Ureteric Injury During Gynecologic Surgery

• At or below the Infundibulo-pelvic ligament.
• Along the course of ureter on the lateral pelvic side wall just above the uterosacral ligament
• Where the ureter passes beneath the uterine vessels
• Beyond the uterine vessels as the ureter passes through the tunnel in the cardinal ligament and turns anteriorly and medially to enter the bladder
• Intramural portion of ureter when it traverses the bladder wall
• Devascularization especially in the lower 1/3rd.

Development of Female Genitalia

• External:
  • Median genital tubercle gives clitoris
  • Medial genital folds give labia minora
  • Lateral genital swellings give labia majora
  • Urogenital membrane gives vestibule, vaginal and urethral orifices
  • The outer layer of the urogenital sinus covers the vaginal orifice as the hymen
• Internal
  • Ovaries Develop as the genital ridge.
  • The surrounding mesoderm migrates to form the cortex and medulla.
  • The future "oogonia" migrate as germ cell from the yolk sac.
  • The ovary descends alongside the "gubernaculum" to become a pelvic organ
• Fallopian tubes, uterus & upper 3/4 or vagina: Develop from “Mullerian ducts” that appear in dorsal aspect of the fetus.descend caudally to pelvis & eventually meet urogenital sinus.canalization occurs with separation of septum in between both ductsexcept its upper free ends Upper non fused ends -> will give fallopian tubes. Lower fused ends -> will give uterus, cervix & upper 3/4 of vagina
• Vagina:Develops from:upper 3/4 lower fused parts of both mullerian ducts and lover 1/4 from urogenital sinus

Congenital Anomalies of Female Genital Tract

• Anomalies of the ovary:
  • Aplasia: No development, leading to primary amenorrhea.
  • Hypoplasia: Causes oligo-hypomenorrhea or premature menopause.
  • Savage syndrome: Receptor defect with no response to FSH and LH
  • Pure Turner's syndrome [45 X0]: Causes primary amenorrhea
  • Mosaic Turner's syndrome: Can present by premature ovarian failure
  • Testicular feminization syndrome (androgen insensitivity): Genotypically male (46 XY and testicles present), phenotypically female (body responds to androgen secreted as estrogen due to absent receptors)
  • Hermaphrodite:
  • True: Containing both ovarian and testicular tissue
  • Female pseudo: Containing ovaries but external genitalia are masculine
  • Male pseudo : Containing testicles but external genitalia are feminine
• Anomalies of the fallopian tube:
  • Aplasia: No development, causing primary infertility
  • Hypoplasia: In the form of a long, narrow, tortuous tube that may cause ectopic pregnancy
  • Accessory Ostium: Congenital diverticulum that may cause ectopic pregnancy
• Anomalies of the uterus:
  • Aplasia: No development.
  • Hypoplasia: Rudimentary solid uterus, infantile, or prepubescent
  • Unicornuate uterus: Absence of one Müllerian duct, one tube, narrow vagina
  • Uterus didelphys: True [2 uteri, 2 cervices, 2 vaginae, 2 vulvae] OR Pseudo “One Vulva Only"
  • Uterus bicornis bicollis: 2 uteri, 2 cervices, and one vagina
  • Septate and sub-septate Uterus – Arcuate uterus: slight depression at the fundus
  • Presentations- Patient may have, 1ry amenorrhea , infertility, dysmennorrhea, AUB, Recurrent abortion , Preterm labor, Ectopic pregnancy, Mal presentation
• Anomalies of the vagina:
• Congenital absence
• Vaginal Septum: May cause Crypto-menorrhea(complete septum) , Dyspareunia(incomplete)
• Congenital Genito-urinary OR Genito-intestinal fistula
• Anomalies of the vulva: – Aplasia or Hypoplasia – Hypertrophy of clitoris – Bifid clitoris – Fusion of the labia minora – Hypertrophy or Asymmetry of the labia

Imperforate Hymen

• Definition: Absence of hymeneal opening
• Diagnosis: Symptoms such as young age (1-2 years after puberty) and cyclic, regular, monthly lower abdominal and pelvic pain (uterine contraction + menstruation)
• If the blood is infected, may lead to headache, malaise, nausea, and elevated temperature
• Amenorrhea is the usual distressing symptom
• Urine retention results from compression by accumulated blood
• Signs include normal changes of puberty and secondary sex characters, possible pelviabdominal swelling due to accumulation of blood, a palpated small mass in front of accumulated blood, and a bluish bulging hymen during a local examination
• Investigations consist of ultrasound and IVP to exclude urological anomalies
• Treatment involves a cruciate or crescent-shaped incision, followed by trimming the edges
• It is treated under complete aseptic technique with the bladder empty .