Ad veri latine efficiantur quo, ea vix nisl euismod explicari. Mel prima vivendum aliquando ut. Sit suscipit tincidunt no, ei usu pertinax molestiae assentior. Eam in nulla regione evertitur. Dico menandri eum an, accusam salutandi et cum, virtute insolens platonem id nec. Ut habeo summo impedit has, sea eius tritani sapientem eu.
Vel laudem legimus ut, consul nominavi indoctum ex pri. Falli omnesque vivendum eos ad, ei hinc diceret eos. Nam no nonumes volumus quaerendum, cu meis graeci audiam vis. In ullum ludus evertitur nec. Solum mentitum quo et, no ancillae legendos mel. With an additional editor and new contributing authors, the new edition combines authoritative detail while signposting essential knowledge.
Retaining the favoured textual features of preceding editions, each chapter is highly structured, with overviews, definitions, aetiology, clinical features, investigation, treatments, key points and additional reading where appropriate. Together with its companion Obstetrics by Ten Teachers, the volume has been edited carefully to ensure consistency of structure, style and level of detail, as well as avoiding overlap of material. For almost a century the 'Ten Teachers' titles have together found favour with students, lecturers and practitioners alike.
The nineteenth editions continue to provide an accessible 'one stop shop' in obstetrics and gynaeology for a new generation of doctors. Key features Fully revised - some chapters completely rewritten by brand-new authors Plentiful illustrations - text supported and enhanced throughout by colour line diagrams and photographs Clear and accessible - helpful features include overviews, key points and summaries Illustrative case histories - engage the reader and provide realistic advice on practicing gynaecology show more.
Product details Format Paperback pages Dimensions x x Table of contents The gynecological history and examination Embryology and anatomy Normal and abnormal sexual development and puberty The normal menstrual cycle Disorders of the menstrual cycle Genital infections in gynecology Fertility control, contraception and abortion Subfertility Problems in early pregnancy Benign diseases of the uterus and cervix Endometriosis and adenomyosis Diseases of the ovary Malignant disease of the uterus Premalignant and malignant disease of the cervix Conditions affecting the vagina and vulva Urogynaecology Pelvic organ prolapse The menopause Psychosocial and ethical aspects of gynecology show more.
Rating details. The longitudinal axis of the uterus is approximately at right angles to the vagina and normally tilts forward. In addition, the long axis of the cervix is rarely the same as the long axis of the uterus. The uterus is also usually flexed forward on itself at the isthmus - antiflexion. However, in around 20 per cent of women, the uterus is tilted backwards - retroversion and retroflexion.
This has no pathological significance. The cavity of the uterus is the shape of an inverted triangle and when sectioned coronally the Fallopian tubes open at lateral angles The constriction at the isthmus where the corpus joins the cervix is the anatomical os. Seen microscopically, the site of the histological internal os is where the mucous membrane of the isthmus becomes that of the cervix. The uterus consists of three layers: the outer serous layer peritoneum , the middle muscular 12 Embryology and anatomy layer myometrium and the inner mucous layer endometrium.
The peritoneum covers the body of the uterus and posteriorly the supravaginal part of the cervix. The peritoneum is intimately attached to a subserous fibrous layer, except laterally where it spreads out to form the leaves of the broad ligament. The muscular myometrium forms the main bulk of the uterus and is made up of interlacing smooth muscle fibres intermingling with areolar tissue, blood vessels, nerves and lymphatics. Externally, these are mostly longitudinal, but the larger intermediate layer has interlacing longitudinal, oblique and transverse fibres.
Internally, they are mainly longitudinal and circular. The inner endometrial layer has tubular glands that dip into the myometrium. The endometrial layer is covered by a single layer of columnar epithelium. Ciliated prior to puberty, this epithelium is mostly lost due to the effects of pregnancy and menstruation. The endometrium undergoes cyclical changes during menstruation and varies in thickness between 1 and 5 mm.
The cervix The cervix is narrower than the body of the uterus and is approximately 2. Lateral to the cervix lies cellular connective tissue called the parametrium. The ureter runs about 1 cm laterally to the supravaginal cervix within the parametrium. The posterior aspect of the cervix is covered by the peritoneum of the pouch of Douglas.
The upper part of the cervix mostly consists of involuntary muscle, whereas the lower part is mainly fibrous connective tissue. It has numerous deep glandular follicles that secrete clear alkaline mucus, the main component of physiological vaginal discharge. The epithelium of the endocervix is columnar and is also ciliated in its upper two thirds.
This is an area of rapid cell division and approximately 90 per cent of cervical cancers arise here. Age changes The disappearance of maternal oestrogens from the circulation after birth causes the uterus to decrease in length by around one third and in weight by around one half. The cervix is then twice the length of the uterus. During childhood, the uterus grows slowly in length, in parallel with height and age.
The average longitudinal diameter ranges from 2.
After the onset of puberty, the anteroposterior and transverse diameters of the uterus start to increase leading to a sharper rise in the volume of the uterus. The increase in uterine volume continues well after menarche and the uterus reaches its adult size and configuration by the late teenage years. After the menopause, the uterus atrophies, the mucosa becomes very thin, the glands almost disappear and the wall becomes relatively less muscular. The Fallopian tubes The Fallopian tube extends outwards from the uterine cornu to end near the ovary. At the abdominal ostium, the tube opens into the peritoneal cavity which is therefore in communication with the exterior of the body via the uterus and the vagina.
This is essential to allow the sperm and egg to meet. The Fallopian tubes convey the ovum from the ovary towards the uterus which promotes oxygenation and nutrition for sperm, ovum and zygote should fertilization occur. The Fallopian tube runs in the upper margin of the broad ligament part of which, known as the mesosalpinx, encloses it so the tube is completely covered with peritoneum, except for a narrow strip along this inferior aspect.
Each tube is about 10 cm long and is described in four parts: 1 The interstitial portion 2 The isthmus 3 The ampulla 4 The infundibulum or fimbrial portion. The interstitial portion lies within the wall of the uterus, while the isthmus is the narrow portion adjoining the uterus. This passes into the widest and longest portion, the ampulla. The opening of the tube into the peritoneal cavity is surrounded by finger-like processes, known as fimbria, into which the muscle coat does not extend. The internal reproductive organs 13 The inner surfaces of the fimbriae are covered by ciliated epithelium which is similar to the lining of the Fallopian tube itself.
One of these fimbriae is longer than the others and extends to and partially embraces the ovary. The muscular fibres of the wall of the tube are arranged in an inner circular and an outer longitudinal layer. The tubal epithelium forms a number of branched folds or plicae which run longitudinally; the lumen of the ampulla is almost filled with these folds. The folds have a cellular stroma, but at their bases the epithelium is only separated from the muscle by a very scanty amount of stroma.
There is no submucosa and there are no glands. The epithelium of the Fallopian tubes contains two functioning cell types; the ciliated cells which act to produce constant current of fluid in the direction of the uterus and the secretory cells which contribute to the volume of tubal fluid. Changes occur under the influence of the menstrual cycle, but there is no cell shedding during menstruation. The ovaries The size and appearance of the ovaries depends on both age and stage of the menstrual cycle.
In a child, the ovaries are small structures approximately 1.
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In the young adult, they are almond-shaped and measure approximately 3 cm long, 1. The ovary is the only intra-abdominal structure not to be covered by peritoneum. Laterally, each ovary is attached to the suspensory ligament of the ovary with folds of peritoneum which becomes continuous with that of the overlying psoas major. Anterior to the ovaries lie the Fallopian tubes, the superior portion of the bladder and the uterovesical pouch. It is bound behind by the ureter where it runs downwards and forwards in front of the internal iliac artery. Structure The ovary has a central vascular medulla consisting of loose connective tissue containing many elastin fibres and non-striated muscle cells.
It has an outer thicker cortex, denser than the medulla consisting of networks of reticular fibres and fusiform cells, although there is no clear-cut demarcation between the two. The surface of the ovaries is covered by a single layer of cuboidal cells, the germinal epithelium. At birth, numerous primordial follicles are found mostly in the cortex, but some are found in the medulla. With puberty, some form each month into the graafian follicles which will at a later stage of development form corpus lutea and ultimately atretic follicles, the corpora albicans.
Vestigial structures Vestigial remains of the mesonephric duct and tubules are always present in young children, but are variable structures in adults. The epoophoron, a series of parallel blind tubules, lies in the broad ligament between the mesovarium and the Fallopian tube. The tubules run to the rudimentary duct of the epoophoron which runs parallel to the lateral Fallopian tube. Situated in the broad ligament between the epoophoron and the uterus are occasionally seen a few rudimentary tubules, the paroophoron.
In a few individuals, the caudal part of the mesonephric duct is well developed running alongside the uterus to the internal os. This is the duct of Gartner. The bladder, urethra and ureter The bladder The vesicle or bladder wall is made of involuntary muscle arranged in an inner longitudinal layer, a middle circular layer and an outer longitudinal layer. It is lined with transitional epithelium and has an average capacity of mL.
The ureters open into the base of the bladder after running medially for about 1 cm through the vesical wall. The urethra leaves the bladder in front of the ureteric orifices. At the internal meatus, the middle layer of vesical muscle forms anterior and posterior loops round the neck of the bladder, some fibres of the loops being continuous with the circular muscle of the urethra.
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It is separated from the anterior vaginal wall below by the pubocervical fascia which stretches from the pubis to the cervix. The urethra The female urethra is about 3. It has a slight posterior angulation at the junction of its lower and middle thirds. The smooth muscle of its wall is arranged in outer longitudinal and inner circular layers. As the urethra passes through the two layers of the urogenital diaphragm triangular ligament , it is embraced by the striated fibres of the deep transverse perineal muscle compressor urethrae and some of the striated fibres of this muscle form a loop on the urethra.
Between the muscular coat and the epithelium is a plexus of veins. There are a number of tubular mucous glands and in the lower part a number of crypts which occasionally become infected. Posteriorly, it is firmly attached in its lower two thirds to the anterior vaginal wall.
This means that the upper part of the urethra is mobile, but the lower part is relatively fixed. Medial fibres of the pubococcygeus of the levator ani muscles are inserted into the urethra and vaginal wall. On voluntary voiding of urine, the base of the bladder and the upper part of the urethra descend and the posterior angle disappears so that the base of the bladder and the posterior wall of the urethra come to lie in a straight line. It was formerly claimed that absence of this posterior angle was the cause of stress incontinence, but this is probably only one of a number of mechanisms responsible.
The ureter As the ureter crosses the pelvic brim, it lies in front of the bifurcation of the common iliac artery. It runs downwards and forwards on the lateral wall of the pelvis to reach the pelvic floor and then passes inwards and forwards attached to the peritoneum of the back of the broad ligament to pass beneath the uterine artery.
It next passes forward through a fibrous tunnel, the ureteric canal, in the upper part of the cardinal ligament. Finally, it runs close to the lateral vaginal fornix to enter the trigone of the bladder. Its blood supply is derived from small branches of the ovarian artery, from a small vessel arising near the iliac bifurcation, from a branch of the uterine artery where it crosses beneath it and from small branches of the vesical artery. Because of is close relationship to the cervix, the vault of the vagina and the uterine artery, the ureter may be damaged during hysterectomy.
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Apart from being cut or tied, in radical procedures, the ureter may undergo necrosis because of interference with its blood supply. It may be displaced upwards by fibromyomata or cysts which are growing between the layers of the broad ligament and may suffer injury if its position is not noticed at operation. The rectum The rectum extends from the level of the third sacral vertebra to a point about 2. Its direction follows the curve of the sacrum and is about 11 cm in length. The front and sides are covered by the peritoneum of the rectovaginal pouch.
In the middle third, only the front is covered by peritoneum. In the lower third, there is no peritoneal covering and the rectum is separated from the posterior wall of the vagina by the rectovaginal fascial septum. Lateral to the rectum are the uterosacral ligaments beside which run some of the lymphatics draining the cervix and vagina.
The pelvic muscles, ligaments and fascia The pelvic diaphragm The pelvic diaphragm is formed by the levator ani muscles which are broad, flat muscles the fibres of which pass downwards and inwards Figure 2. The two muscles, one on either side, constitute the pelvic diaphragm. The rectum 15 lliococcygeus Urethra Pubococcygeus base. During micturition, this loop relaxes to allow the bladder neck and upper urethra to open and descend. Urogenital diaphragm The urogenital diaphragm triangular ligament is made up of two layers of pelvic fascia which fill the gap between the descending pubic rami and lies beneath the levator ani muscles.
The deep transverse perineal muscles compressor urethrae lies between the two layers and the diaphragm is pierced by the urethra and vagina. The perineal body Figure 2. The muscle is described in two parts: 1 The pubococcygeus which arises from the pubic bone and the anterior part of the tendinous arch of the pelvic fascia white line 2 The iliococcygeus which arises from the posterior part of the tendinous arch and the ischial spine. The medial borders of the pubococcygeus muscle pass on either side from the pubic bone to the preanal raphe.
They thus embrace the vagina and on contraction have some sphincteric action. The nerve supply is from the third and fourth sacral nerves. The pubococcygeus muscles support the pelvic and abdominal viscera, including the bladder. The medial edge passes beneath the bladder and runs laterally to the urethra, into which some of its fibres are inserted. Together with the fibres from the opposite muscle, they form a loop which maintains the angle between the posterior aspect of the urethra and the bladder This is a mass of muscular tissue that lies between the anal canal and the lower third of the vagina.
Its apex is at the lower end of the rectovaginal septum at the point where the rectum and posterior vaginal walls come into contact. Its base is covered with skin and extends from the fourchette to the anus. It is the point of insertion of the superficial perineal muscles and is bounded above by the levator ani muscles where they come into contact in the midline between the posterior vaginal wall and the rectum.
The pelvic peritoneum The peritoneum is reflected from the lateral borders of the uterus to form on either side a double fold of peritoneum - the broad ligament. Despite the name, this is not a ligament but a peritoneal fold and it does not support the uterus.
The Fallopian tube runs in the upper free edge of the broad ligament as far as the point at which the tube opens into the peritoneal cavity. The mesosalpinx, the portion of the broad ligament which lies above the ovary is layered; between its layers are to be seen any Wolffian remnants which may remain. The ureter is attached to the posterior leaf of the broad ligament at this point.
The ovary is attached to the posterior layer of the broad ligament by a short mesentry the mesovarium through which the ovarian vessels and nerves enter the hilum. The round ligament is the continuation of the same structure and runs forwards under the anterior leaf of peritoneum to enter the inguinal canal ending in the subcutaneous tissue of the labium major. The pelvic fascia and pelvic cellular tissue Connective tissue fills the irregular spaces between the various pelvic organs.
Much of it is loose cellular tissue, but in some places it is condensed to form strong ligaments which contain some smooth muscle fibres and which form the fascial sheaths which enclose the various viscera. The pelvic arteries, veins, lymphatics, nerves and ureters runs though it.
The cellular tissue is continuous above with the extraperitoneal tissue of the abdominal wall, but below it is cut off from the ischiorectal fossa by the pelvic fascia and the lavatory ani muscles. The pelvic fascia may be regarded as a specialized part of this connective tissue and has parietal and visceral components. The parietal pelvic fascia lines the wall of the pelvic cavity covering the obturator and pyramidalis muscles. There is a thickened tendinous arch or white line on the side wall of the pelvis. It is here that the levator ani muscle arises and the cardinal ligament gains its lateral attachment.
Where the parietal pelvic fascia encounters bone, as in the pubic region, it blends with the periosteum. It also forms the upper layer of the urogenital diaphragm triangular ligament. Each viscus has a fascial sheath which is dense in the case of the vagina and cervix and at the base of the bladder, but is tenuous or absent over the body of the uterus and the dome of the bladder. These are two strong fan-shaped fibromuscular bands which pass from the cervix and vaginal vault to the side wall of the pelvis on either side. In the erect position, they are almost vertical in direction and support the cervix.
The blood supply Arteries supplying the pelvic organs Because the ovary develops on the posterior abdominal wall and later migrates down into the pelvis, it carries its blood supply with it directly from the abdominal aorta. The ovarian artery arises from the aorta just below the renal artery and runs downwards on the surface of the psoas muscle to the pelvic brim, where it crosses in front of the ureter and then passes into the infundibulopelvic fold of the broad ligament Figure 2.
The artery divides into branches that supply the ovary and tube and then run on to reach the uterus where they anastamose with the terminal branches of the uterine artery. The internal iliac hypogastic artery This vessel is about 4 cm in length and begins at the bifurcation of the common iliac artery in front of the sacroiliac joint.
It soon divides into anterior and posterior branches: the branches that supply the pelvic organs are all from the anterior division. The uterine artery provides the main blood supply to the uterus. The artery first runs downwards on the lateral wall of the pelvis, in the same direction as the ureter. It then turns inward and forwards lying in the base of the broad ligament. On reaching the wall of the uterus, the artery turns upwards to run tortuously to the upper part of the uterus, where it anastamoses with the ovarian artery.
In this part of its course, it sends many branches into the substance of the uterus. The uterine artery supplies a branch to the ureter as it crosses it and shortly afterwards another branch is given off to supply the cervix and upper vagina. The vaginal artery is another branch of the internal iliac artery that runs at a lower level to supply the vagina. The vesical arteries are variable in numbers and supply the bladder and terminal ureter. One usually runs in the roof of the ureteric canal.
The blood supply 17 Abdominal aorta Left common iliac artery Right common iliac artery Internal iliac artery External iliac artery Obturator artery Umbilical artery Uterine artery Vaginal artery Middle rectal artery Pubic symphysis Levator ani muscle Iliolumbar artery Lateral sacral artery gluteal artery Inferior gluteal artery Internal pudendal artery Internal pudendal artery in pudendal canal Alcock Median sacral artery Superior gluteal artery Inferior gluteal artery Uterine artery Vaginal Inferior vesical artery Inferior rectal artery Inferior vena cava Abdominal aorta Right common iliac artery Left common iliac artery Ureters External iliac artery Internal iliac artery Uterus Umbilical artery Medial Umbilical ligament occluded part of umbilical artery Figure 2.
The middle rectal artery often arises in common with the lowest vesical artery. The pudendal artery is another branch of the internal iliac artery. It leaves the pelvic cavity through the sciatic foramen and, after winding round the ischial spine, enters the ischiorectal fossa where it gives off the inferior rectal artery.
It terminates in branches that supply the perineal and vulval arteries, including the erectile tissue of the vestibular bulbs and clitoris. The superior rectal artery This artery is the continuation of the inferior mesenteric artery and descends in the base of the mesocolon. It divides into two branches which run on either side of the rectum and supply numerous branches to it. Venous drainage from the rectal plexus is via the superior rectal veins to the inferior mesenteric veins, and the middle and inferior rectal veins to the internal pudendal veins and so to the iliac veins.
The ovarian veins on each side begin in the pampiniform plexus that lies between the layers of the broad ligament. At first, there are two veins on each side accompanying the corresponding ovarian artery. Higher up the vein becomes single, with that on the right ending in the inferior vena cava and that on the left in the left renal vein. The pelvic lymphatics Lymph draining from all the lower extremities and the vulva and perineal regions is all filtered through the inguinal and superficial femoral nodes before continuing along the deep pathways on the side wall of the pelvis. One deep chain passes upwards lateral to the major blood vessels, forming in turn the external iliac, common iliac and para-aortic groups of nodes.
Medially, another chain of vessels passes from the deep femoral nodes through the femoral canal to the obturator and internal iliac groups of nodes. These last nodes are interspersed among the origins of the branches of the internal iliac artery receiving lymph directly from the organs supplied by this artery including the upper vagina, cervix and body of the uterus. From the internal iliac and common iliac nodes, afferent vessels pass up the para-aortic chains and finally all lymphatic drainage from the legs and pelvis flows into the lumbar lymphatic trunks and cisterna chyli at the level of the second lumbar vertebra.
From here, all the lymph is carried by the thoracic duct through the thorax with no intervening nodes to empty into the junction of the left subclavian and internal jugular veins. Tumour cells that penetrate or bypass the pelvic and para-aortic nodes are rapidly disseminated via the great veins at the root of the neck. Lymphatic drainage from the genital tract The pelvic veins The veins around the bladder, uterus, vagina and rectum form plexuses which intercommunicate freely.
Venous drainage from the uterine, vaginal and The lymph vessel from individual parts of the genital tract drain into this system of pelvic lymph nodes in the following manner: The vulva and perineum medial to the labiocrural skin folds contain superficial lymphatics which pass 18 Embryology and anatomy upwards towards the mons pubis, then curve laterally to the superficial and inguinal nodes. Drainage from these is through the fossa ovalis into the deep femoral nodes.
The largest of these, lying in the upper part of the femoral canal, is known as the node of Cloquet. The lymphatics of the lower third of the vagina follow the vulval drainage to the superficial lymph nodes, whereas those from the upper two thirds pass upwards to join the lymphatic vessels of the cervix.
The lymphatics of the cervix pass either laterally in the base of the broad ligament or posteriorly along the uterosacral ligaments to reach the side wall of the pelvis. Radical surgery for carcinoma of the cervix should include removal of all these node groups on both sides of the pelvis. Most of the lymphatic vessels of the body of the uterus join those of the cervix and therefore reach similar groups of nodes.
A few vessels at the fundus follow the ovarian channels and there is an inconsistent pathway along the round ligament to the inguinal nodes. The ovary and Fallopian tube have a plexus of vessels which drain along the infundibulopelvic fold to the para-aortic nodes on both sides of the midline. On the left, these are found around the left renal pedicle, while on the right there may only be one node intervening before the lymph flows into the thoracic duct thus accounting for the rapid early spread of metastatic carcinoma to distant sites such as the lungs.
The lymphatic drainage of the bladder and upper urethra is to the iliac nodes, while those of the lower part of the urethra follow those of the vulva. Lymphatics from the lower anal canal drain to the superficial inguinal nodes and the remainder of the rectal drainage follows pararectal channels accompanying the blood vessels to both the internal iliac nodes middle rectal artery and the para-aortic nodes and the origin of the inferior mesenteric artery.
Nerves of the pelvis Nerve supply of the vulva and perineum The pudendal nerve arises form the second, third and fourth sacral nerves. As it passes along the outer wall of the ischiorectal fossa, it gives off an inferior rectal branch and divides into the perineal nerve and dorsal nerve of the clitoris Figure 2.
The perineal nerve gives the sensory supply to the vulva and also innervates the anterior part of the external anal canal and levator ani and the superficial perineal muscles. The dorsal nerve of the clitoris is sensory. Sensory fibres from the mons and labia also pass in the ilioinguinal and genitofemoral nerves to the first lumbar root. The posterior femoral cutaneous nerve carries sensation from the perineum to the small sciatic nerve and thus to the first second and third sacral nerves.
The main nerve supply of the levator ani muscles comes from the third and fourth sacral nerves. Nerve supply of the pelvic viscera The innervation of the pelvic viscera is complex and not well understood. All pelvic viscera receive dual innervation, i. Nerve fibres of the preaortic plexus Abdominal aorta Rectum plexus Sacral splanchnic nerves nerve Superior hypogastric plexus Common iliac artery and plexus Internal iliac artery and plexus External iliac artery and plexus Inferior hypogastric pelvic Pelvic nerves parasympathetic Uterus Rectum Figure 2. Below this, the superior hypogastric plexus divides and on each side its fibres are continuous with fibres passing beside the rectum to join the uterovaginal plexus inferior hypogastric plexus or plexus of Frankenhauser.
This plexus lies in the loose cellular tissue posterolateral to the cervix, below the uterosacral folds of peritoneum. Parasympathetic fibres from the second, third and fourth sacral nerves join the uterovaginal plexus. Fibres from or to the bladder, uterus, vagina and rectum join the plexus. The uterovaginal plexus contains a few ganglion cells, so it is likely that a few motor cells also have their relay stations there and then pass onward with the blood vessels onto the viscera.
The ovary is not innervated by the nerves already described, but from the ovarian plexus which surrounds the ovarian vessels and joins the preaortic plexus high up. A thorough understanding of these mechanisms is fundamental in understanding how the normal fetus develops. Sexual differentiation Differentiation of the fertilized embryo into a male or female fetus is controlled by the sex chromosomes. All normal fetuses have an undifferentiated gonad which has the potential to become either a testis or an ovary. In addition, all fetuses have both Mullerian and Wolffian ducts and the potential to develop male or female internal and external genitalia.
The chromosomal complement of the zygote determines whether the indifferent gonad becomes a testis or an ovary. The first step in this pathway is dependent on the SRY gene sex determining region of the Y chromosome. This gene, helped by other testes-determining genes, causes the gonad to begin development into a testis. SRY gene Testis determing factor Figure 3. Disorders of sex development 21 As the gonad develops into a testis, it differentiates into two cell types.
Anti-Mullerian hormone suppresses development of the Mullerian ducts. Testosterone stimulates the Wollfian ducts to develop into the vas deferens, epididymis and seminal vesicles. In addition, in the external genital skin, testosterone is converted by an enzyme called 5-alpha-reductase into dihydrotestosterone DHT. This acts to virilize the external genitalia. The genital tubercle becomes the penis and the labioscrotal folds fuse to form the scrotum. The urogenital folds fuse along the ventral surface of the penis and include the urethra so that it opens at the tip of the penis.
Where the gonad becomes an ovary, the absence of AMH allows the Mullerian structures to develop. The proximal two thirds of the vagina develops from the paired Mullerian ducts which grow in a caudal and medial direction and fuse in the midline. These ducts form bilateral Fallopian tubes, and midline fusion of these structures produces the uterus, cervix and upper vagina. The rudimentary distal vagina fuses with the posterior urethra at week 7 to form the urogenital sinus.
The vagina then develops from a combination of the Mullerian tubercles and the urogenital sinus. These fuse to form the vaginal plate which extends from the Mullerian ducts to the urogenital sinus. This plate begins to canalize, starting at the hymen and proceeds upwards to the cervix. A diagrammatic representation of the basic pathways is given in Figure 3. The external genitalia do not virilize and, in the absence of testosterone, the genital tubercle becomes the clitoris and the labioscrotal swellings form the labia. The lower part of the vagina is formed from the urogenital folds.
Disorders of sex development Disorders of sex development are conditions where the sequence of events described above does not happen. The clinical consequences of this depend upon where within the sequence the variation occurs. These may be diagnosed at birth with ambiguous or abnormal genitalia, but may also be seen at puberty in girls who present with primary amenorrhoea or increasing virilization.
There has been a recent change in the terminology used to refer to these conditions. The new terminology is summarized in Table 3. Table 3. This is usually incompatible with life, except in the case of Turner syndrome which results from a complete or partial absence on one X chromosome 45X0. Turner syndrome is the most common chromosomal anomaly in females, occurring in 1 in live female births. Although there can be variation among affected women, most have typical clinical features including short stature, webbing of the neck and a wide carrying angle.
Associated medical conditions include coarctation of the aorta, inflammatory bowel disease, sensorineural and conduction deafness, renal anomalies and endocrine dysfunction, such as autoimmune thyroid disease. In this condition, the ovary does not complete its normal development and only the stroma is present at Previous Proposed 22 Normal and abnormal sexual development and puberty birth. Diagnosis is usually made at birth or in early childhood from the clinical appearance of the baby or due to short stature during childhood. However, in about 10 per cent of women, the diagnosis is not made until adolescence with delayed puberty.
The ovaries do not produce oestrogen, so the normal physical changes of puberty cannot happen. In childhood, treatment is focused on growth, but in adolescence it focuses on induction of puberty. Pregnancy is possible, but ovum donation is usually required. Psychological input and support is important. XY gonadal dysgenesis In this situation, the gonads do not develop into a testis, despite the presence of an XY karyotype. In about 10 per cent of cases, this is due to an absent SRY gene, but in most cases the cause is unknown.
In complete gonadal dysgenesis Swyer syndrome , the gonad remains as a streak gonad and does not produce any hormones. In the absence of AMH, the Mullerian structures do not regress and the uterus, vaginal and Fallopian tubes develop normally. The absence of testosterone mean the fetus does not virilize. The baby is phenotypically female, although has an XY chromosome. The gonads do not function and presentation is usually at adolescence with failure to go into spontaneous puberty. The dysgenetic gonad has a high malignancy risk and should be removed when the diagnosis is made.
This is usually performed laparoscopically. Puberty must be induced with oestrogen and pregnancies have been reported with a donor oocyte. Full disclosure of the diagnosis including the XY karytoype is essential, although can be devastating and psychological input is crucial. Mixed gonadal dysgenesis is a more complex condition. The karyotype may be 46 XX, but mosaicism, e. In this situation, both functioning ovarian and testicular tissue can be present and if so this condition is known as ovotesticular DSD.
The anatomical findings vary depending on the function of the gonads. For example, if the testes is functional, then the baby will virilize and have ambiguous or normal male genitalia. The Mullerian structures are usually absent on the side of the functioning testes, but a unicorcuate uterus may be present if there is an ovary or streak gonad. At the appropriate time, these testes secrete AMH leading to the regression of the Mullerian ducts. Hence, CAIS women do not have a uterus.
Testosterone is also produced at the appropriate time, however, due to the inability of the androgen receptor to respond, the external genitalia do not virilize and instead undergo female development. A female fetus is born with normal female external genitalia, an absent uterus and testes found at some point in their line of descent through the abdomen from the pelvis to the inguinal canal. During puberty, breast development will be normal, however, the effects of androgens are not seen, so pubic and axillary hair growth will be minimal.
Presentation is usually at puberty with primary amenorrhoea, although if the testes are in the inguinal canal they can cause a hernia in a younger girl. Once the diagnosis is made, initially management is psychological with full disclosure of the XY karyotype and the information that the patient will be infertile. Gonadectomy is recommended because of the small long-term risk of testicular malignancy, although this can be deferred until after puberty.
Obstetrics by Ten Teachers, 19th Edition
Once the gonads are removed, long-term hormone replacement therapy will be required. The vagina is usually shortened and treatment will be required to create a vagina suitable for penetrative intercourse. Vaginal dilation is the most effective method of improving vaginal length and entails the insertion of vaginal moulds of gradually increasing length and width for at least 30 minutes a day Figure 3.
Surgical vaginal reconstruction operations are reserved for those women that have failed a dilation treatment programme. In cases of partial androgen insensitivity, the androgen receptor can respond to some extent with limited virilization. The child is usually diagnosed at birth with ambiguous genitalia. However, the fetus is unable Disorders of sex development 23 Figure 3. Dilation is the first line of treatment for women with a shortened or absent vagina, such as in MRKH syndrome. Presentation is usually with ambiguous genitalia at birth, but can also be with increasing virilization at puberty of a female child due to the large increase in circulating testosterone with the onset of puberty.