Gynaecology by Ten Teachers 19th Edition PDF

GYNAECOLOGY by TenTeachers 19th edition First published in 1919 as ‘Diseases of Women’, Gynaecology by Ten Teachers is well established as a concise, yet comprehensive, guide within its field. The nin...

GYNAECOLOGY by TenTeachers 19th edition First published in 1919 as ‘Diseases of Women’, Gynaecology by Ten Teachers is well established as a concise, yet comprehensive, guide within its field. The nineteenth edition has been thoroughly updated, integrating clinical material with the latest scientific advances. 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, investigations, treatments, key points and additional reading where appropriate. Together with its companion Obstetrics by Ten Teachers, the volume has been edited carefully to ensure 19th edition 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 gynaecology for a new generation of doctors. Key features l Fully revised – some chapters completely rewritten by brand-new authors l Plentiful illustrations – text supported and enhanced throughout by colour line diagrams and photographs Monga andDobbs l Clear and accessible – helpful features include overviews, key points and symptoms & signs indicators l Illustrative case histories – engage the reader and provide realistic advice on practising gynaecology About the editors Ash Monga BMed (Sci) BM BS MRCOG is Consultant Gynaecologist, Princess Anne Hospital, Southampton University Hospitals NHS Trust, Southampton, UK Stephen Dobbs MD FRCOG is Consultant Gynaecological Oncologist, Belfast City Hospital, Belfast Trust, Belfast, UK 19th edition Resources supporting this book are available online at www.hodderplus.com/obsgynaebytenteachers I S B N 978-0-340-98354-6 where readers will find an image library from the book PLUS complimentary access to the images from the companion volume, Obstetrics by Ten Teachers 9 780340 983546 983546_Gynae_TenT_CV.indd 1 28/01/2011 17:47  GYNAECOLOGY byTenTeachers GynaecologyTenTeach_1st.indb 1 25/01/2011 13:05 This page intentionally left blank  GYNAECOLOGY byTenTeachers 19th Edition Edited By Ash Monga BMed (Sci) BM BS MRCOG Consultant Gynaecologist, Princess Anne Hospital, Southampton University Hospitals NHS Trust, Southampton, UK Stephen Dobbs MD FRCOG Consultant Gynaecological Oncologist, Belfast City Hospital, Belfast Trust, Belfast, UK GynaecologyTenTeach_1st.indb 3 25/01/2011 13:05 CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2011 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Version Date: 20121026 International Standard Book Number-13: 978-1-4441-4956-2 (eBook - PDF) This book contains information obtained from authentic and highly regarded sources. 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Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com  Contents The Ten Teachers vii Acknowledgements viii Commonly used abbreviations ix CHAPTER 1 The gynaecological history and examination 1 CHAPTER 2 Embryology and anatomy 7 CHAPTER 3 Normal and abnormal sexual development and puberty 20 CHAPTER 4 The normal menstrual cycle 27 CHAPTER 5 Disorders of the menstrual cycle 34 CHAPTER 6 Genital infections in gynaecology 49 CHAPTER 7 Fertility control, contraception and abortion 62 CHAPTER 8 Subfertility 85 CHAPTER 9 Problems in early pregnancy 94 CHAPTER 10 Benign diseases of the uterus and cervix 99 CHAPTER 11 Endometriosis and adenomyosis 104 CHAPTER 12 Diseases of the ovary 110 CHAPTER 13 Malignant disease of the uterus 120 CHAPTER 14 Premalignant and malignant disease of the cervix 125 CHAPTER 15 Conditions affecting the vagina and vulva 134 CHAPTER 16 Urogynaecology 141 CHAPTER 17 Pelvic organ prolapse 154 CHAPTER 18 The menopause 163 CHAPTER 19 Psychosocial and ethical aspects of gynaecology 181 Appendix 1 192 Appendix 2 196 Index 198 GynaecologyTenTeach_1st.indb 5 25/01/2011 13:05 This page intentionally left blank  The Ten Teachers Susan Bewley MB BS MD FRCOG MA (Law and Ethics) Janesh Gupta MSc MD FRCOG Consultant Obstetrician, Guy’s and St Thomas’ NHS Professor of Obstetrics and Gynaecology, University Foundation Trust and Honorary Senior Lecturer, of Birmingham, Birmingham Women’s Hospital, Kings College London, UK Birmingham, UK Ying Cheong MB ChB BAO MA MD MRCOG Timothy Hillard DM FFSRH FRCOG Senior Lecturer and Honorary Consultant in Consultant Obstetrician and Gynaecologist, Poole Obstetrics and Gynaecology; Clinical Director, Hospital NHS Foundation Trust, Poole, UK Complete Fertility Centre, Southampton, UK Andrew Horne PhD MRCOG Sarah M Creighton MD FRCOG Senior Lecturer and Consultant Gynaecologist, Consultant Gynaecologist, University College University of Edinburgh, Centre for Reproductive Hospital, London, UK Biology, Queen’s Medical Research Institute, Edinburgh, UK Stephen Dobbs MD FRCOG Consultant Gynaecological Oncologist, Belfast City Ash Monga BMed (Sci) BM BS MRCOG Hospital, Belfast Trust, UK Consultant Gynaecologist, Princess Anne Hospital, Southampton University Hospital NHS Trust, Ailsa E Gebbie MB ChB FRCOG FFSRH DCH Southampton, UK Consultant in Community Gynaecology, NHS Lothian Family Planning Services, Edinburgh, UK David Nunns MD FRCOG Consultant Gynaecological Oncologist, Nottingham City Hospital, Nottingham, UK GynaecologyTenTeach_1st.indb 7 25/01/2011 13:05  Acknowledgements The editors would like to acknowledge the excellent contributions of additional authors Carolyn Ford, Kirsty Munro, Nisha Krishnan and Sameer Umranikar, who are not Ten Teachers but without whose significant help this volume would not have been completed. I would like to thank my wife Susan and my girls Madeleine and Betsy for their constant support and Jan, my secretary. (AM) I would like to acknowledge my wife Jenny and children Harry, Anna and Ellie for their support and love. (SD) GynaecologyTenTeach_1st.indb 8 25/01/2011 13:05  Commonly Used Abbreviations bHCG b-human chorionic gonadotrophin HNPCC hereditary non-polyposis colorectal AFP a fetoprotein cancer syndrome AMH anti-Mullerian hormone HPO hypothalamic-pituitary-ovarian AUC area under the curve HPV human papilloma virus BEO bleeding of endometrial origin HRT hormone replacement therapy BEP bleomycin and etoposide HSG hysterosalpingogram BMI body mass index HyCoSy hysterocontrast synography BNF British National Formulary ICSI intracytoplasmic sperm injection BRCA breast ovarian cancer syndrome IGFBP insulin-like growth factor binding CAIS complete androgen insensitivity proteins syndrome IMB intermenstrual bleeding CBAVD congenital bilateral absence of the vas IUI intrauterine insemination deferens IUS intrauterine system CBT cognitive-behavioural therapy IVF in vitro fertilization CC clomifene citrate LAM lactational amenorrhoea method CCVR combined contraceptive vaginal ring LARC long-acting reversible contraception CEE conjugated equine oestrogen LAVH laparoscopy-assisted vaginal CF cystic fibrosis hysterectomy CHD coronary heart disease LH luteinizing hormone CIN cervical intraepithelial neoplasia LLETZ large loop excision of transformation COC combined oral contraception zone CT computed tomography LNG-IUS levonorgestrel intrauterine systems D&E dilatation of the cervix and LOD laparoscopic ovarian drilling evacuation of the uterus MBL menstrual blood loss DHT dihydrotestosterone MDT multidisciplinary team DI donor insemination MRI magnetic resonance imaging DOA detrusor overactivity MVA manual vacuation aspiration DSD disorders of sex development NAATs nucleic acid amplification tests DUB dysfunctional uterine bleeding NSAID non-steroidal anti-inflammatory EC emergency contraception drug ED every day OAB overactive bladder EE ethinyl estradiol OHSS ovarian hyperstimulation syndrome EGF epidermal growth factor OI ovulation induction EOC epithelial ovarian cancer PAF platelet activating factor ERPC evacuation of products of conception PCOS polycystic ovarian syndrome ESR erythrocyte sedimentation rate PID pelvic inflammatory disease ESS endometrial stromal sarcomas PMB post-menopausal bleeding FBC full blood count PMS premenstrual syndrome FGF fibroblast growth factor POF premature ovarian failure FGM female genital mutilation POP progestogen-only pill; pelvic organ FSH follicle-stimulating hormone prolapse GFR glomerular filtration rate PPC primary peritoneal carcinoma GnRH gonadotrophin-releasing hormone RCOG Royal College of Obstetricians and GTD gestational trophoblastic disorder Gynaecologists GUM genitourinary medicine RMI risk of malignancy index HDR high dose radiotherapy SCJ squamocolumnar junction HIV human immunodeficiency virus SERM selective oestrogen receptor HMB heavy menstrual bleeding modulator GynaecologyTenTeach_1st.indb 9 25/01/2011 13:05  SLN sentinel lymph node UAE uterine artery embolization SSR surgical sperm retrieval USI urodynamic stress incontinence SSRIs selective serotonin reuptake USS ultrasound scan inhibitors UTI urinary tract infection STI sexually transmitted infection VAIN vaginal intraepithelial neoplasia TGF transforming growth factors VCU videocystourethrography TLH total laparoscopic hysterectomy VEGF vascular endothelial growth factor TSH thyroid stimulating hormone VIN vulval intraepitheial neoplasia TVS transvaginal ultrasound scan VTE venous thromboembolism TVT tension-free vaginal tape WHO World Health Organization TZ transformation zone GynaecologyTenTeach_1st.indb 10 25/01/2011 13:05  C HA P TER 1 Th e gy n a ecolog ica l his to ry a n d e x a min atio n History 1 Examination 3 Overview A careful and detailed history is essential before the examination of any patient. In addition to a good general history, focusing on the history of the presenting complaint will allow you to customize the examination to elicit the appropriate signs and make an accurate diagnosis. The gynaecological examination should always be conducted with appropriate privacy and sensitivity with a chaperone present. History recognize that some women may feel obliged to have their mother/partner present and may not provide all The consultation should ideally be held in a closed the relevant information with them present. At least room with adequate facilities and privacy. Many some part of the consultation or examination should women will feel anxious or apprehensive about the be with the woman alone to allow her to answer any forthcoming consultation, so it is important that the specific queries more openly. examiner establishes initial rapport with the patient It is important to be aware of the different attitudes and puts them at ease. The examiner should be to various women’s health issues in a religious and introduced by name (a handshake often helps) and culturally diverse population. Appropriate respect should check the patient’s details. Ideally, there should and sensitivity should always be shown. be no more than one other person in the room, but Enough time should be allowed for the patient any student or attending nurse should be introduced to express herself and the doctor’s manner should be by name and their role briefly explained. one of interest and understanding, while guiding her A number of women attend with their partner with appropriate questioning. A history that is taken or close family member or friend. Provided the with sensitivity will often encourage the patient to patient herself consents to this, there is no reason to reveal more details which may be relevant to future exclude them from the initial consultation, but this management. should be limited to one person. In some instances, A set template should be used for history taking, the additional person may be required to be a key as this prevents the omission of important points and part of the consultation, i.e. if there is a language or will help direct the consultation. A sample template comprehension difficulty. However, it is important to is given below. GynaecologyTenTeach_1st.indb 1 25/01/2011 13:05  2 The gynaecological history and examination Symptoms † General Name, age and occupation Sexual and contraceptive history The type of contraception used and any problems with it £ A brief statement of the general nature and duration of the Establish whether the patient is sexually active and whether main complaints (try to use the patient’s own words rather there are any difficulties or pain during intercourse. than medical terms at this stage) Menopause (where relevant) History of presenting complaint Date of last period This section should focus on the presenting complaint, e.g. Any post-menopausal bleeding menstrual problems, pain, subfertility, urinary incontinence, Any menopausal symptoms. etc. The detailed questions relating to each complaint are covered in more detail in the relevant chapters, but there are Previous gynaecological history certain important aspects of a gynaecological history that This section should include any previous gynaecological should always be enquired about. treatments or surgery. Menstrual history Previous obstetric history Age of menarche Number of children with ages and birth weights. Usual duration of each period and length of cycle (usually Any abnormalities with pregnancy, labour or the written as mean number of days of bleeding over usual puerperium length of full cycle, e.g. 5/28) Number of miscarriages and gestation at which they occurred First day of the last period Any terminations of pregnancy with record of gestational Pattern of bleeding: regular or irregular and length of cycle age and any complications. Amount of blood loss: more or less than usual, number Previous medical history of sanitary towels or tampons used, passage of clots or flooding Any serious illnesses or operations with dates Any intermenstrual or post-coital bleeding Family history. Any pain relating to the period, its severity and timing of Enquiry about other systems onset Appetite, weight loss, weight gain Any medication taken during the period (including over-the- Bowel function (if urogynaecological complaint, more detail counter preparations). may be required) Pelvic pain Bladder function (if urogynaecological complaint, more Site of pain, its nature and severity detail may be required). Anything that aggravates or relieves the pain – specifically Enquiry of other systems. enquire about relationship to menstrual cycle and intercourse Social history Does the pain radiate anywhere or is it associated with bowel Sensitive enquiry should be made about the woman’s social or bladder function (menstrual pain often radiates through to situation including details of her occupation, who she lives with, the sacral area of the back and down the thighs)? her housing and whether or not she’s in a stable relationship. Vaginal discharge A history regarding smoking and alcohol intake should also be obtained. Any pertinent family or other relevant social problems Amount, colour, odour, presence of blood should be briefly discussed. If admission and surgery are being Relationship to the menstrual cycle contemplated it’s necessary to establish what support she has Any history of sexually transmitted diseases (STDs) or at home, particularly if she is elderly or frail. recent tests Summary Any vaginal dryness (post-menopausal). The history should be summarized in one to two sentences Cervical screening before proceeding to the examination to focus the problem and Date of last smear and any previous abnormalities. alert the examiner to the salient features. GynaecologyTenTeach_1st.indb 2 25/01/2011 13:05  Examination 3 Examination waist down, but the area from the xiphisternum to the symphysis pubis should be left exposed (Figure Important information about the patient can be 1.1). It is usual to examine the women from her obtained on watching them walk into the examination right hand side. Abdominal examination comprises room. Poor mobility may affect decisions regarding inspection, palpation, percussion and, if appropriate, surgery or future management. auscultation. Any examination should always be carried out with the patient’s consent and with appropriate Inspection privacy and sensitivity. Ideally, a chaperone should be The contour of the abdomen should be inspected present throughout the examination. and noted. There may be an obvious distension or A general examination should always be mass. The presence of surgical scars, dilated veins or performed initially which should include examining striae gravidarum (stretch marks) should be noted. the hands and mucous membranes for evidence of It is important specifically to examine the umbilicus anaemia. The supraclavicular area should be palpated for laparoscopy scars and just above the symphysis for the presence of nodes, particularly on the left pubis for Pfannenstiel scars (used for Caesarean side where in cases of abdominal malignancy one section, hysterectomy, etc.). The patient should be might palpate the enlarged Virchow’s node (this is asked to raise her head or cough and any hernias or also known as Troissier’s sign). The thyroid gland divarication of the rectus muscles will be evident. should be palpated. The chest and breasts should always be examined as part of a full examination; Palpation this is particularly relevant if there is a suspected First, if the patient has any abdominal pain she should ovarian mass, as there may be a breast tumour with be asked to point to the site – the area should not secondaries of the ovaries known as Krukenburg be examined until the end of palpation. Palpation tumours. In addition, a pleural effusion may be using the right hand is performed examining the elicited as a consequence of abdominal ascites. A left lower quadrant and proceeding in a total of four general neurological assessment should be performed, steps to the right lower quadrant of the abdomen. but more specific testing should be limited to cases Palpation should include examination for masses, where there is a suspicion of underlying neurological the liver, spleen and kidneys. If a mass is present but problems. The next step should be to proceed to one can palpate below it, then it is more likely to be abdominal and pelvic examination. an abdominal mass rather than a pelvic mass. It is important to remember that one of the characteristics Abdominal examination of pelvic mass is that one cannot palpate below it. If the patient has pain her abdomen should be palpated The patient should empty her bladder before the gently and the examiner should look for signs of abdominal examination. peritonism, i.e. guarding and rebound tenderness. The patient should be comfortable and lying The patient should also be examined for inguinal semi-recumbent with a sheet covering her from the hernias and lymph nodes. Percussion Percussion is particularly useful if free fluid is suspected. In the recumbent position, ascitic fluid will settle down into a horseshoe shape and dullness is the flanks can be demonstrated. As the patient moves over to her side, the dullness will move to her lowermost side. This is known as ‘shifting dullness’. A fluid thrill can also be elicited. An enlarged bladder due to urinary retention will also be dull to percussion and this should be demonstrated to Figure 1.1 A patient in the correct position for abdominal the examiner (many pelvic masses have disappeared examination showing obvious abdominal distension. after catheterization!). GynaecologyTenTeach_1st.indb 3 25/01/2011 13:05  4 The gynaecological history and examination Auscultation Speculum This method is not specifically useful for the A speculum is an instrument which is inserted into gynaecological examination. However, a patient will the vagina to obtain a clearer view of part of the sometimes present with acute abdomen with bowel vagina or pelvic organs. There are two principal obstruction or a postoperative patient with ileus, types in widespread use. The first is a bi-valve or and therefore listening for bowel sounds may be Cusco’s speculum (Figure 1.2a), which holds back the appropriate. anterior and posterior walls of the vagina and allows visualization of the cervix when opened out (Figure Pelvic examination 1.2b). It has a retaining screw that can be tightened to allow the speculum to stay in place while a procedure Before proceeding to a vaginal examination, the or sample is taken from the cervix, e.g. smear or swab. patient’s verbal consent should be obtained and a A Sim’s speculum (Figure 1.3a) is used in the left lateral female chaperone should be present for any intimate position (Figure 1.3b). This is particularly useful for examination. Unless the patient’s complaint is of examination of prolapse as it allows inspection of the urinary incontinence, it is preferable for the patient to vaginal walls. The choice of speculum will depend on empty her bladder before the examination. If a urine the patient’s presenting problem. infection is suspected, a midstream sample should be Increasingly, plastic disposable speculums collected at this point. It should go without saying that are being used, but if it is a metal one it is usual to the examiner should wear gloves for this part of the warm the speculum to make the examination more procedure. There are three components to the pelvic comfortable for the patient. Excessive lubrication examination. should be avoided and if a smear is being taken, Inspection lubrication with anything other than water should be The external genitalia and surrounding skin, avoided. including the peri-anal area, are first inspected under a good light with the patient in the dorsal position, Bimanual examination the hips flexed and abducted and knees flexed. The This is usually performed after the speculum left lateral position can also be used (see below). The examination and is performed to assess the pelvic patient is asked to strain down to enable detection of organs. It is a technique that requires practice. There any prolapse and also to cough, as this may show the are a variety of ‘model pelvises’ which can be used sign of stress incontinence. to train the student in the basics of the examination. (a) (b) Figure 1.2 (a) Cusco’s speculum; (b) Cusco’s speculum in position. The speculum should be inserted at about 45° to the vertical and rotated to the vertical as it is introduced. Once it is fully inserted, the blades should be opened up to visualize the cervix. GynaecologyTenTeach_1st.indb 4 25/01/2011 13:05  Examination 5 (a) (b) Figure 1.3 (a) Sim’s speculum; (b) Sim’s speculum inserted with the patient in the left lateral position. The speculum is being used to hold back the posterior vaginal walls to allow inspection of the anterior wall and vault. The speculum can be rotated 180° or withdrawn slowly to visualize the posterior wall. Some universities are now utilizing gynaecology (antiverted) or posterior (retroverted) and freely teaching assistants who are paid volunteers who allow mobile and non-tender. The tips of the fingers are themselves to be examined and will talk the student then placed into each lateral fornix to palpate the through the examination. It is customary to use the adenexae (tubes and ovaries) on each side. The fingers left hand to part the labia and expose the vestibule are pushed backwards and upwards, while at the same and then insert one or two fingers of the right hand time pushing down in the corresponding area with into the vagina. The fingers are passed upwards and the fingers of the abdominal hand (Figure 1.4b). It is backwards to reach the cervix (Figure 1.4a). The unusual to be able to feel normal ovaries, except in cervix is palpated and any irregularity, hardness or very thin women. Any swelling or tenderness is noted, tenderness noted. The left hand is now placed on although remember that normal ovaries can be very the abdomen below the umbilicus and pressed down tender when directly palpated. The posterior fornix into the pelvis to palpate the fundus of the uterus. should also be palpated to identify the uterosacral The size, shape, position, mobility, consistency and ligaments which may be tender or scarred in women tenderness are noted. The normal uterus is pear- with endometriosis. shaped and about 9 cm in length. It is usually anterior (a) (b) Figure 1.4 (a) Bimanual examination of the pelvis assessing the uterine position and size; (b) bimanual examination of the lateral fornix. GynaecologyTenTeach_1st.indb 5 25/01/2011 13:05  6 The gynaecological history and examination Rectal examination Key Points A rectal examination can be used as an alternative to The consultation should be performed in a private a vaginal examination in children and in adults who environment and in a sensitive fashion have never had sex. It is less sensitive than a vaginal The examiner should introduce him/herself, be courteous examination and can be quite uncomfortable, but it and explain what is about to happen and why. will help pick up a pelvic mass. In some situations, The examiner should be familiar with the history template a rectal examination can also be useful as well as and use it regularly to avoid omissions. a vaginal examination to differentiate between Remember to summarize the history before proceeding to an enterocele and a rectocele or to palpate the the examination. uterosacral ligaments more thoroughly. Occasionally, A chaperone should always be present for an intimate a rectovaginal examination (index finger in the vagina examination. and middle finger in the rectum) may be useful to The examiner should be sensitive to the patient’s needs identify a lesion in the rectovaginal septum. and anxiety and respect her privacy and dignity. Investigations The examination should always begin with a general assessment of the patient. Once the examination is complete, the patient should The patient should be asked to inform the examiner if the be given the opportunity to dress in privacy and examination is uncomfortable. come back into the consultation room to sit down The examiner should reassure the patient during the and discuss the findings. You should now be able examination and give feedback about what is being done. to give a summary of the whole case and formulate After the examination, the examiner should make sure that a differential diagnosis. This will then determine the the patient is comfortable and allow her to get dressed in appropriate further investigations (if any) that should privacy. be needed. Swabs and smears should be taken at the The examiner should explain the findings to the patient time of the examination and a midstream specimen in suitable language and give her the opportunity to ask of urine (MSU) when the patient empties her questions. bladder before the examination. The need for further investigations, such as ultrasound, colposcopy and Prepare a differential diagnosis and order any appropriate urodynamics, is discussed in the relevant chapters. investigations. GynaecologyTenTeach_1st.indb 6 25/01/2011 13:05  C HA P TER 2 Em b ryology a n d a n ato m y Embryology 7 The rectum 14 Anatomy 9 The blood supply 16 The internal reproductive organs 10 Nerves of the pelvis 18 Overview A good understanding of the embryological development and resulting genital anatomy is essential. This is particularly important with respect to the congenital anomalies described in Chapter 3, but also underpins basic understanding of the impact of all gynaecological disease processes. Embryology During the 5th week of gestation, they acquire a central mesenchymal core from the extra-embryonic mesoderm and become branched, forming the The normal early pregnancy secondary villi. The appearance of embryonic blood vessels within their mesenchymal cores transformsthe Implantation and subsequent placental development secondary villi into tertiary villi. Up to 10 weeks’ in the human require complex adaptive changes of the gestation, which corresponds to the last week of the uterine wall constituents. embryonic period (stages 19 to 23), villi cover the Development of the blastocyst entire surface of the chorionic sac. As the gestational sac grows during fetal life, At the beginning of the 4th week after the last the villi associated with the decidua capsularis menstrual period, the implanted blastocyst is surrounding the amniotic sac become compressed composed, from outside to inside, of the trophoblastic and degenerate, forming an avascular shell known ring, the extra-embryonic mesoderm and the as the chorion laeve, or smooth chorion. Conversely, amniotic cavity and the primary yolk sac, separated by the villi associated with the decidua basalis proliferate, the bilaminar embryonic disk. The extra-embryonic forming the chorion frondosum or definitive placenta. mesoderm progressively increases, and 12 days after ovulation (around the 26th menstrual day) it contains Normal placentation isolated spaces that rapidly fuse to form the extra- As soon as the blastocyst has hatched, the tropho- embryonic coelom. As the latter forms, the primary ectoderm layer attaches to the cell surface of the yolk sac decreases in size and the secondary yolk sac endometrium and, by simple displacement, early arises from cells growing from the embryonic disk trophoblastic penetration within the endometrial inside the primary yolk sac. stroma occurs. Progressively, the entire blastocyst will sink into maternal decidua and the migrating Formation of the placenta trophoblastic cells will encounter venous channels of Primary chorionic villi develop between 13 and 15 increasing size, then superficial arterioles and, during days after ovulation (end of 4th week of gestation). the 4th week, the spiral arteries. The trophoblastic Simultaneously, blood vessels start to develop in cells infiltrate deep into the decidua and reach the the extra-embryonic mesoderm of the yolk sac, the deciduo-myometrial junction at between 8 and connecting stalk and the chorion. The primary villi 12 weeks’ gestation. This extravillous trophoblast are composed of a central mass of cytotrophoblast penetrates the inner third of the myometrium via the surrounded by a thick layer of syncytiotrophoblast. interstitial ground substance and affects its mechanical GynaecologyTenTeach_1st.indb 7 25/01/2011 13:05  8 Embryology and anatomy and electrophysiological properties by increasing its Plasma testing expansile capacity. The trophoblastic infiltration of Measurement of hCG in plasma is more accurate the myometrium is progressive and achieved before (detection limit around 0.1–0.3iu/L) and is able 18 weeks’ gestation in normal pregnancies. to detect a pregnancy 6–7 days after ovulation, Ultrasound imaging which corresponds to the time of implantation. The gestational sac representing the deciduo-placental Measurement of hCG levels may help to diagnose interface and the chorionic cavity are the first ectopic pregnancy and is of pivotal importance in the sonographic evidence of a pregnancy. The gestational follow-up of some pregnancy disorders. sac can be visualized with transvaginal ultrasound The mechanism of sex differentiation into a around 4.4–4.6 weeks (32–34 days) following the female or male fetus is described in Chapter 3. Once onset of the last menstruation, when it reaches a size the gonad has become an ovary, subsequent female of 2–4 mm. By contrast, the gestational sac can only be development follows. observed by means of abdominal ultrasound imaging during the 5th week post-menstruation. The ovary The first embryonic structure that becomes visible At approximately 4–5 weeks of embryonic life, inside the chorionic cavity is the secondary yolk sac, genital ridges are formed overlying the embryonic when the gestational sac reaches 8 mm. Demonstration kidney. At this stage, these are identical in both of the yolk sac reliably indicates that an intrauterine sexes. The primitive gonad is formed between 5 and fluid collection represents a true gestational sac, thus 7 weeks of gestation, when undifferentiated germ excluding the possibility of a pseudosac or an ectopic cells migrate from the yolk sac to the genital ridges. pregnancy. In the absence of male determinants, the primitive Symptomatology gonad becomes an ovary. Granulosa cells derived The classical symptom triad for early pregnancy from the proliferating coelomic epithelium surround disorders is amenorrhoea, pelvic or low abdominal the germ cells and form primordial follicles. Each pain and vaginal bleeding. Pregnancy symptoms are primordial follicle consists of an oocyte within a often non-specific and many women of reproductive single layer of granulosa cells. Theca cells develop age have irregular menstrual cycles. The first test to from the proliferating coelomic epithelium and are confirm the existence of pregnancy is for the detection separated from the granulosa cells by a basal lamina. of human chorionic gonadotrophin (hCG) in the The maximum number of primordial follicles is patient’s urine or plasma. reached at 20 weeks gestation when at this time there are six to seven million primordial follicles present. Pregnancy tests The numbers of these reduce by atresia and by birth one to two million are present. Atresia continues Human chorionic gonadotrophin is a placental- throughout childhood and by menstruation 300 000 derived glycoprotein, composed of two subunits, to 400 000 are present. alpha and beta, which maintains the corpus luteum The development of an oocyte within a primordial for the first 7 weeks of gestation. Extremely small follicle is arrested at the prophase of its first meiotic quantities of hCG are produced by the pituitary gland division. It remains in that state until it regresses or and thus plasma hCG is almost exclusively produced enters the meiotic process shortly before ovulation. by the placenta. Human chorionic gonadotrophin has a half-life of 6–24 hours and rises to a peak in The uterus and vagina pregnancy at 9–11 weeks’ gestation. The genital system develops in close association Urine testing with the urinary system. During the fifth week of It is possible to detect low levels of hCG in urine by embryonic life, the nephrogenic duct develops from rapid (1–2 min) dipstick tests. The sensitivity of these the mesoderm and forms the urogenital ridge and tests is high (detection limit of around 50iu/L) and mesonephric duct (Figure 2.1). The mesonephric they produce positive results around 14 days after duct (also named the Wolffian duct) develops under ovulation. the influence of testosterone into vas deferens, GynaecologyTenTeach_1st.indb 8 25/01/2011 13:05  Anatomy 9 Mesonephric duct Paramesonephric Mesonephric ducts ducts Hindgut Fallopian tube Gubernaculum of ovary Ovary Genital ridge Mesonephros Degenerating Developing mesonephric uterus duct Müllerian Figure 2.1 Cross section diagram of the posterior tubercle abdominal wall showing genital ridge. Urogenital sinus epididymus and seminal vesicle. In the female fetus, Figure 2.2 Caudal part of the paramesonephric duct (top) the Wolffian system regresses. The female reproductive fusion to form uterus and Fallopian tubes. tracts develop from paired ducts which are adjacent to the mesonephric duct and so are called the paramesonephric ducts (or Mullerian ducts). These Anatomy extend caudally to project into the posterior wall of the urogenital sinus as the Mullerian tubercle. These fuse in the midline distally to form the uterus, cervix and The external genitalia proximal two thirds of the vagina. The unfused caudal segments form the Fallopian tubes. The distal vagina The external genitalia is commonly called the vulva is formed from the sinovaginal bulbs in the upper and includes the mons pubis, labia majora and portion of the urogenital sinus (Figure 2.2). minora, the vaginal vestibule, the clitoris and the greater vestibular glands (Figure 2.3). The mons pubis The external genitalia is a fibro-fatty pad covered by hair-bearing skin which covers the body of the pubic bones. Between the fifth and seventh weeks of life, the The labia majora are two folds of skin with cloacal folds which are a pair of swellings adjacent to underlying adipose tissue lying either side of the the cloacal membrane fuse anteriorly to become the vagina opening. They contain sebaceous and sweat genital tubercle. This will become the clitoris. The glands and a few specialized apocrine glands. In the perineum develops and divides the cloaca membrane deepest part of each labium is a core of fatty tissue into an anterior urogenital membrane and a posterior continuous with that of the inguinal canal and the anal membrane. The cloacal folds anteriorly are fibres of the round ligament terminate here. called the urethral folds which form the labia minora. The labia minora are two thin folds of skin that Another pair of folds within the cloacal membrane lie between the labia majora. These vary in size and form the labioscrotal folds which eventually become may protrude beyond the labia major where they are the labia majora. The urogenital sinus becomes the visible, but may also be concealed by the labia majora. vestibule of the vagina. The external genitalia are Anteriorly, they divide in two to form the prepuce and recognizably female by the end of 12 weeks gestation. frenulum of the clitoris (clitoral hood). Posteriorly, GynaecologyTenTeach_1st.indb 9 25/01/2011 13:05  10 Embryology and anatomy In the prepubertal vulva, no hair is present and there is little adipose deposition. During puberty, pubic hair develops and fat deposition within the labia gives a more womanly shape. After the menopause, with the fall in oestrogen levels, the labia minora lose fat and become thinner, but may become elongated. The vaginal opening becomes smaller. The internal reproductive organs The vagina Figure 2.3 Adult female external gentalia. The vagina is a fibromuscular canal lined with stratified squamous epithelium that leads from the they divide to form a fold of skin called the fourchette uterus to the vulva (Figure 2.4). It is longer in the at the back of the vagina introitus. They contain posterior wall (approximately 9 cm) than in the sebaceous glands, but have no adipose tissue. They anterior wall (approximately 7 cm). The vaginal walls are not well developed before puberty and atrophy are normally in apposition, except at the vault where after the menopause. Both the labia minora and labia they are separated by the cervix. The vault of the majora become engorged during sexual arousal. vagina is divided into four fornices: posterior, anterior The clitoris is an erectile structure measuring and two lateral. approximately 0.5–3.5 cm in length. The body of The mid-vagina is a transverse slit while the the clitoris is the main part of the visible clitoris and lower vagina is an H-shape in transverse section. is made up of paired columns of erectile tissue and The vaginal walls are lined with transverse folds. vascular tissue called the ‘corpora cavernosa’. These The vagina has no glands and is kept moist by become the crura at the bottom of the clitoris and secretions from the uterine and cervical glands run deeper and laterally. The vestibule is the cleft and by transudation from its epithelial lining. The between the labia minora. It contains openings of epithelium is thick and rich in glycogen which the urethra, the Bartholin’s glands and the vagina. increases in the post-ovulatory phase of the cycle. The vagina is surrounded by two bulbs of erectile However, before puberty and after the menopause, and vascular tissue which are extensive and almost the vagina is devoid of glycogen due to the lack completely cover the distal vaginal wall. These have of oestrogen. Doderlein’s bacillus is a normal traditionally been named the bulb of the vaginal commensal of the vaginal flora and breaks down vestibule, although recent work on both dissection glycogen to form lactic acid and producing a pH of and magnetic resonance imaging (MRI) suggests that around 4.5. This has a protective role for the vagina they may be part of the clitoris and should be renamed in decreasing the growth of pathogenic bacteria. ‘clitoral bulbs’. Their function is unknown but they The upper posterior wall forms the anterior probably add support to the distal vaginal wall to peritoneal reflection of the pouch of Douglas. The enhance its rigidity during penetration. middle third is separated from the rectum by pelvic The Bartholin’s glands are bilateral and about fascia and the lower third abuts the perineal body. the size of a pea. They open via a 2-cm duct into Anteriorly, the vagina is in direct contact with the the vestibule below the hymen and contribute to base of the bladder, while the urethra runs down lubrication during intercourse. the lower half in the midline to open into the The hymen is a thin covering of mucous vestibule. Its muscles fuse with the anterior vagina membrane across the entrance to the vagina. It wall. Laterally, at the fornices, the vagina is related is usually perforated which allows menstruation. to the cardinal ligaments. Below this are the levator The hymen is ruptured during intercourse and any ani muscles and the ischiorectal fossae. The cardinal remaining tags are called ‘carunculae myrtiformes’. ligaments and the uterosacral ligaments which form GynaecologyTenTeach_1st.indb 10 25/01/2011 13:05  The internal reproductive organs 11 Suspensory ligament of ovary Uterine Right tube ureter Ovarian Ovary ligament Recto-uterine External iliac fold vessels Rectouterine recess Fundus of uterus Posterior part of fornix Vesicouterine recess Cervix uteri Bladder Rectal Urethra ampulla Vagina Anal canal Figure 2.4 Saggital section female pelvis. posteriorly from the parametrium support the upper above the cornu is called the ‘fundus’. The uterus part of the vagina. tapers to a small constricted area, the isthmus, and At birth, the vagina is under the influence below this is the cervix which projects obliquely of maternal oestrogens so the epithelium is well into the vagina. The longitudinal axis of the uterus developed. After a couple of weeks, the effects of the is approximately at right angles to the vagina and oestrogen disappear and the pH rises to 7 and the normally tilts forward. This is called ‘anteversion’. In epithelium atrophies. At puberty, the reverse occurs addition, the long axis of the cervix is rarely the same and finally at the menopause the vagina tends to as the long axis of the uterus. The uterus is also usually shrink and the epithelium atrophies. flexed forward on itself at the isthmus – antiflexion. However, in around 20 per cent of women, the uterus The uterus is tilted backwards – retroversion and retroflexion. This has no pathological significance. The uterus is shaped like an inverted pear tapering The cavity of the uterus is the shape of an inverted inferiorly to the cervix and in its non-pregnant state triangle and when sectioned coronally the Fallopian is situated entirely within the pelvis. It is hollow and tubes open at lateral angles The constriction at has thick, muscular walls. Its maximum external the isthmus where the corpus joins the cervix is dimensions are approximately 7.5 cm long, 5 cm wide the anatomical os. Seen microscopically, the site and 3 cm thick. An adult uterus weighs approximately of the histological internal os is where the mucous 70 g. In the upper part, the uterus is termed the body membrane of the isthmus becomes that of the cervix. or ‘corpus’. The area of insertion of each Fallopian The uterus consists of three layers: the outer tube is termed the ‘cornu’ and that part of the body serous layer (peritoneum), the middle muscular GynaecologyTenTeach_1st.indb 11 25/01/2011 13:05  12 Embryology and anatomy layer (myometrium) and the inner mucous layer Age changes (endometrium). The peritoneum covers the body The disappearance of maternal oestrogens from the of the uterus and posteriorly the supravaginal part circulation after birth causes the uterus to decrease of the cervix. The peritoneum is intimately attached in length by around one third and in weight by to a subserous fibrous layer, except laterally where around one half. The cervix is then twice the length it spreads out to form the leaves of the broad of the uterus. During childhood, the uterus grows ligament. slowly in length, in parallel with height and age. The The muscular myometrium forms the main bulk average longitudinal diameter ranges from 2.5 cm at of the uterus and is made up of interlacing smooth the age of two years, to 3.5 cm at ten years. After the muscle fibres intermingling with areolar tissue, blood onset of puberty, the anteroposterior and transverse vessels, nerves and lymphatics. Externally, these are diameters of the uterus start to increase leading to a mostly longitudinal, but the larger intermediate layer sharper rise in the volume of the uterus. The increase has interlacing longitudinal, oblique and transverse in uterine volume continues well after menarche and fibres. Internally, they are mainly longitudinal and the uterus reaches its adult size and configuration by circular. the late teenage years. After the menopause, the uterus The inner endometrial layer has tubular glands atrophies, the mucosa becomes very thin, the glands that dip into the myometrium. The endometrial layer almost disappear and the wall becomes relatively less is covered by a single layer of columnar epithelium. muscular. Ciliated prior to puberty, this epithelium is mostly lost due to the effects of pregnancy and menstruation. The Fallopian tubes The endometrium undergoes cyclical changes during menstruation and varies in thickness between 1 and The Fallopian tube extends outwards from the uterine 5 mm. 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 The cervix body via the uterus and the vagina. This is essential to allow the sperm and egg to meet. The Fallopian tubes The cervix is narrower than the body of the uterus convey the ovum from the ovary towards the uterus and is approximately 2.5 cm in length. Lateral to which promotes oxygenation and nutrition for sperm, the cervix lies cellular connective tissue called the ovum and zygote should fertilization occur. parametrium. The ureter runs about 1 cm laterally The Fallopian tube runs in the upper margin to the supravaginal cervix within the parametrium. of the broad ligament part of which, known as the The posterior aspect of the cervix is covered by the mesosalpinx, encloses it so the tube is completely peritoneum of the pouch of Douglas. covered with peritoneum, except for a narrow strip The upper part of the cervix mostly consists of along this inferior aspect. Each tube is about 10 cm involuntary muscle, whereas the lower part is mainly long and is described in four parts: fibrous connective tissue. The mucous membrane of the cervical canal (endocervix) has anterior and 1 The interstitial portion posterior columns from which folds radiate out, 2 The isthmus the ‘arbour vitae’. It has numerous deep glandular 3 The ampulla follicles that secrete clear alkaline mucus, the main 4 The infundibulum or fimbrial portion. component of physiological vaginal discharge. The epithelium of the endocervix is columnar and is The interstitial portion lies within the wall of also ciliated in its upper two thirds. This changes to the uterus, while the isthmus is the narrow portion stratified squamous epithelium around the region of adjoining the uterus. This passes into the widest and the external os and the junction of these two types of longest portion, the ampulla. This, in turn, terminates epithelium is called the ‘squamocolumnar junction’ in the extremity known as the ‘infundibulum’. or transformation zone. This is an area of rapid cell The opening of the tube into the peritoneal cavity division and approximately 90 per cent of cervical is surrounded by finger-like processes, known as cancers arise here. fimbria, into which the muscle coat does not extend. GynaecologyTenTeach_1st.indb 12 25/01/2011 13:05  The internal reproductive organs 13 The inner surfaces of the fimbriae are covered by fibres and non-striated muscle cells. It has an outer ciliated epithelium which is similar to the lining of thicker cortex, denser than the medulla consisting the Fallopian tube itself. One of these fimbriae is of networks of reticular fibres and fusiform cells, longer than the others and extends to and partially although there is no clear-cut demarcation between embraces the ovary. The muscular fibres of the wall of the two. The surface of the ovaries is covered by a the tube are arranged in an inner circular and an outer single layer of cuboidal cells, the germinal epithelium. longitudinal layer. Beneath this is an ill-defined layer of condensed The tubal epithelium forms a number of branched connective tissue called the ‘tunica albuginea’, which folds or plicae which run longitudinally; the lumen of increases in density with age. At birth, numerous the ampulla is almost filled with these folds. The folds primordial follicles are found mostly in the cortex, have a cellular stroma, but at their bases the epithelium but some are found in the medulla. With puberty, is only separated from the muscle by a very scanty some form each month into the graafian follicles amount of stroma. There is no submucosa and there which will at a later stage of development form are no glands. The epithelium of the Fallopian tubes corpus lutea and ultimately atretic follicles, the contains two functioning cell types; the ciliated cells corpora albicans. which act to produce constant current of fluid in the direction of the uterus and the secretory cells which Vestigial structures contribute to the volume of tubal fluid. Changes occur Vestigial remains of the mesonephric duct and under the influence of the menstrual cycle, but there is tubules are always present in young children, but no cell shedding during menstruation. are variable structures in adults. The epoophoron, a series of parallel blind tubules, lies in the broad The ovaries ligament between the mesovarium and the Fallopian tube. The tubules run to the rudimentary duct of The size and appearance of the ovaries depends on the epoophoron which runs parallel to the lateral both age and stage of the menstrual cycle. In a child, Fallopian tube. Situated in the broad ligament between the ovaries are small structures approximately 1.5 cm the epoophoron and the uterus are occasionally seen long; however, they increase to adult size in puberty a few rudimentary tubules, the paroophoron. In a few due to proliferation of stromal cells and commencing individuals, the caudal part of the mesonephric duct maturation of the ovarian follicles. In the young adult, is well developed running alongside the uterus to the they are almond-shaped and measure approximately internal os. This is the duct of Gartner. 3 cm long, 1.5 cm wide and 1 cm thick. After the men- opause, no active follicles are present and the ovary becomes smaller with a wrinkled surface. The ovary is The bladder, urethra and ureter the only intra-abdominal structure not to be covered by peritoneum. Each ovary is attached to the cornu of The bladder the uterus by the ovarian ligament and at the hilum The vesicle or bladder wall is made of involuntary to the broad ligament by the mesovarium which con- muscle arranged in an inner longitudinal layer, a tains its supply of nerves and blood vessels. Laterally, middle circular layer and an outer longitudinal layer. each ovary is attached to the suspensory ligament of It is lined with transitional epithelium and has an the ovary with folds of peritoneum which becomes average capacity of 400 mL. continuous with that of the overlying psoas major. The ureters open into the base of the bladder after Anterior to the ovaries lie the Fallopian tubes, the running medially for about 1 cm through the vesical superior portion of the bladder and the uterovesical wall. The urethra leaves the bladder in front of the pouch. It is bound behind by the ureter where it runs ureteric orifices. The triangular area lying between the downwards and forwards in front of the internal iliac ureteric orifices and the internal meatus of the ureter artery. is known as the ‘trigone’. At the internal meatus, the middle layer of vesical muscle forms anterior and Structure posterior loops round the neck of the bladder, some The ovary has a central vascular medulla consisting fibres of the loops being continuous with the circular of loose connective tissue containing many elastin muscle of the urethra. GynaecologyTenTeach_1st.indb 13 25/01/2011 13:05  14 Embryology and anatomy The base of the bladder is adjacent to the cervix, of the broad ligament to pass beneath the uterine with only a thin layer of tissue intervening. It is artery. It next passes forward through a fibrous tunnel, separated from the anterior vaginal wall below by the the ureteric canal, in the upper part of the cardinal pubocervical fascia which stretches from the pubis to ligament. Finally, it runs close to the lateral vaginal the cervix. fornix to enter the trigone of the bladder. Its blood supply is derived from small branches of The urethra the ovarian artery, from a small vessel arising near the The female urethra is about 3.5 cm long and is lined iliac bifurcation, from a branch of the uterine artery with transitional epithelium. It has a slight posterior where it crosses beneath it and from small branches of angulation at the junction of its lower and middle the vesical artery. thirds. The smooth muscle of its wall is arranged Because of is close relationship to the cervix, the in outer longitudinal and inner circular layers. As vault of the vagina and the uterine artery, the ureter the urethra passes through the two layers of the may be damaged during hysterectomy. Apart from urogenital diaphragm (triangular ligament), it is being cut or tied, in radical procedures, the ureter embraced by the striated fibres of the deep transverse may undergo necrosis because of interference with perineal muscle (compressor urethrae) and some its blood supply. It may be displaced upwards by of the striated fibres of this muscle form a loop on fibromyomata or cysts which are growing between the the urethra. Between the muscular coat and the layers of the broad ligament and may suffer injury if epithelium is a plexus of veins. There are a number of its position is not noticed at operation. tubular mucous glands and in the lower part a number of crypts which occasionally become infected. In its upper two thirds, the urethra is separated from the The rectum symphysis by loose connective tissue, but in its lower third it is attached to the pubic ramus on each side by The rectum extends from the level of the third sacral strong bands of fibrous tissue called the ‘pubourethral vertebra to a point about 2.5 cm in front of the coccyx tissue’. Posteriorly, it is firmly attached in its lower where it passes through the pelvic floor to become two thirds to the anterior vaginal wall. This means continuous with the anal canal. Its direction follows that the upper part of the urethra is mobile, but the the curve of the sacrum and is about 11 cm in length. lower part is relatively fixed. The front and sides are covered by the peritoneum of Medial fibres of the pubococcygeus of the levator the rectovaginal pouch. In the middle third, only the ani muscles are inserted into the urethra and vaginal front is covered by peritoneum. In the lower third, wall. When they contract, they pull the anterior there is no peritoneal covering and the rectum is vaginal wall and the upper part of the urethra separated from the posterior wall of the vagina by the forwards forming an angle of about 100° between rectovaginal fascial septum. Lateral to the rectum are the posterior wall of the urethra and the bladder the uterosacral ligaments beside which run some of base. On voluntary voiding of urine, the base of the the lymphatics draining the cervix and vagina. bladder and the upper part of the urethra descend and the posterior angle disappears so that the base The pelvic muscles, ligaments and fascia of the bladder and the posterior wall of the urethra come to lie in a straight line. It was formerly claimed The pelvic diaphragm that absence of this posterior angle was the cause of The pelvic diaphragm is formed by the levator ani stress incontinence, but this is probably only one of a muscles which are broad, flat muscles the fibres of number of mechanisms responsible. which pass downwards and inwards (Figure 2.5). The two muscles, one on either side, constitute the pelvic The ureter diaphragm. The muscle arises by linear origin from: As the ureter crosses the pelvic brim, it lies in front of the bifurcation of the common iliac artery. It runs the lower part of the body of the os pubis; downwards and forwards on the lateral wall of the the internal surface of the parietal pelvic fascia along the white line; pelvis to reach the pelvic floor and then passes inwards and forwards attached to the peritoneum of the back the pelvic surface of the ischial spine. GynaecologyTenTeach_1st.indb 14 25/01/2011 13:05  The rectum 15 Pubococcygeus base. During micturition, this loop relaxes to allow the Urethra 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 Vagina 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 Rectum This is a mass of muscular tissue that lies between the Iliococcygeus anal canal and the lower third of the vagina. Its apex Figure 2.5 Pelvic floor musculature. 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 The levator ani muscles are inserted into: is bounded above by the levator ani muscles where the preanal raphe and the central point of the perineum where one muscle meets the other on they come into contact in the midline between the posterior vaginal wall and the rectum. the opposite side; The pelvic peritoneum the wall of the anal canal, where the fibres blend with the deep external sphincter muscle; The peritoneum is reflected from the lateral borders the postanal or anococcygeal raphe, where again one muscle meets the other on the opposite side; of the uterus to form on either