Obstetrics Lecture I PDF

Lela Tandashvili Obstetrician and Gynecologist  Lecture I External generative organs Internal generative organs The bony pelvis Pelvis size and its clinical estimations The basic principles of evidence based medicine Randomized studies and meta-analysi...

Lela Tandashvili Obstetrician and Gynecologist  Lecture I External generative organs Internal generative organs The bony pelvis Pelvis size and its clinical estimations The basic principles of evidence based medicine Randomized studies and meta-analysis of obstetrics Legal issues in obstetrics “Anatomy is the only solid foundation of medicine; it is to the physician and surgeon what geometry is to the astronomer” Dr. William Hunter  External generative organs Mons pubis Labia majora Labia minora Bartholin glands Clitoris The area containing these organs is called the vulva The three main functions of external genital organs Enabling sperm to enter the body Protecting the internal genital organs from infectious organisms Providing sexual pleasure  The mons pubis The mons pubis is a rounded mound of fatty tissue that covers the pubic bone During puberty, it becomes covered with hair The mons pubis contains oil-secreting (sebaceous) glands that release substances that are involved in sexual attraction (pheromones)  Labia majora and Labia minora The labia majora are relatively large, fleshy folds of tissue that enclose and protect the other external genital organs. During puberty, hair appears on the labia majora The labia minora lie just inside the labia majora and surround the openings to the vagina and urethra. A rich supply of blood vessels gives the labia minora a pink color  Bartholin glands Located beside the vaginal opening When stimulated Bartholin Glands secrete a thick fluid that supplies lubrication for intercourse  Clitoris The clitoris, located between the labia minora at their upper end, is a small protrusion that corresponds to the penis in the male  Internal generative organs Vagina Uterus Fallopian tubes Ovaries  Vagina The vagina is a tubelike, muscular but elastic organ about 10-12cm long in an adult woman The lower third of the vagina is surrounded by elastic muscles that control the diameter of its opening The vagina is lined with a mucous membrane, kept moist by fluids produced by cells on its surface and by secretions from glands in the cervix  Uterus The uterus is a thick-walled, muscular, pear-shaped organ located in the middle of the pelvis, behind the bladder, and in front of the rectum. The uterus is anchored in position by several ligaments The main function of the uterus is to sustain a developing fetus The uterus consists of the following: The cervix The main body (corpus)  The cervix The cervix is the lower part of the uterus, which protrudes into the upper part of the vagina. It can be seen during a pelvic examination. Like the vagina, the cervix is lined with a mucous membrane Sperm can enter and menstrual blood can exit the uterus through a channel in the cervix (cervical canal) The cervix is usually a good barrier against bacteria, except around the time an egg is released by the ovaries (ovulation), during the menstrual period, or during labor  The cervix The channel through the cervix is lined with glands that secrete mucus. This mucus is thick and impenetrable to sperm until just before ovulation. At ovulation, the mucus becomes clear and elastic (because the level of the hormone estrogen increases) The mucus-secreting glands of the cervix can store live sperm for up to about 5 days  The corpus of the uterus The corpus of the uterus, which is highly muscular, can stretch to accommodate a growing fetus. Its muscular walls contract during labor to push the baby out through the cervix and the vagina During the reproductive years, the corpus weighs approximately 70gr and is twice as long as the cervix At term uterus weighs approximately 1100gr  The corpus of the uterus The corpus of the uterus has 3 layers: Endometrium-Functional and Basalis Myometrium Serosa  Fallopian tubes Fallopian Tubes are 8 to 14cm in length Anatomically classified as an: 1. interstitial portion 2. Isthmus 3. Ampulla 4. Infundibulum  Ovaries Ovaries measure 2.5-5cm in length They usually lie in the upper part of the pelvic cavity and rest on the lateral wall of the pelvis-Ovarian fossa of Waldeyer The Ovary consists of cortex and medulla The cortex contains oocytes and developing follicules  The pelvis The pelvis is composed of four bones: The sacrum coccyx Two innominate bones Each innominate bone is formed by the fusion of three bones: The ilium Ischium Pubis Both innominate bones are joined to the sacrum at the sacroiliac synchondroses and to one another at the symphysis pubis  The False and True Pelvis The pelvis is conceptually divided into false and true components The false pelvis lies above the linea terminalis The true pelvis is below this anatomical boundary The false pelvis is bounded posteriorly by the lumbar vertebra and laterally by the iliac fossa  The ischial spines Extending from the middle of the posterior margin of each ischium are the ischial spines These are of great obstetrical importance because the distance between them usually represents the shortest diameter of the true pelvis ischial spines also serve as valuable landmarks in assessing the level to which the presenting part of the fetus has descended into the true pelvis  The sacrum The sacrum forms the posterior wall of the true pelvis. Its upper anterior margin corresponds to the promontory that may be felt during bimanual pelvic examination in women with a small pelvis. It can provide a landmark for clinical pelvimetry Normally, the sacrum has a marked vertical and a less pronounced horizontal concavity, which in abnormal pelvis may undergo important variations. A straight line drawn from the promontory to the tip of the sacrum usually measures 10 cm, whereas the distance along the concavity averages 12 cm  Pelvic Joints Anteriorly, the pelvic bones are joined together by the symphysis pubis This structure consists of fibrocartilage and the superior and inferior pubic ligaments The latter ligament is frequently designated the arcuate ligament of the pubis Posteriorly, the pelvic bones are joined by articulations between the sacrum and the iliac portion of the innominate bones to form the sacroiliac joints  Pelvic Joints Pelvic Joints in general have a limited degree of mobility, however during pregnancy, there is remarkable relaxation of these joints at term, caused by upward gliding of the sacroiliac joint The displacement, which is greatest in the dorsal lithotomy position, may increase the diameter of the outlet by 1.5 to 2.0 cm. This is the main justification for placing a woman in this position for a vaginal delivery  McRoberts maneuver Sacroiliac joint mobility is also the likely reason that the McRoberts maneuver often is successful in releasing an obstructed shoulder in a case of shoulder dystocia  Planes and Diameters of the Pelvis The pelvis is described as having four imaginary planes: 1. The plane of the pelvic inlet—the superior strait 2. The plane of the pelvic outlet—the inferior strait 3. The plane of the midpelvis—the least pelvic dimensions 4. The plane of greatest pelvic dimension—of no obstetrical significance  pelvic inlet Four diameters of the pelvic inlet are usually described Anteroposterior Transverse Two oblique diameters The anteroposterior diameter, termed the true conjugate, extends from the uppermost margin of the symphysis pubis to the sacral promontory  obstetrical conjugate The clinically important obstetrical conjugate is the shortest distance between the sacral promontory and the symphysis pubis. Normally, this measures 10 cm or more, but unfortunately, it cannot be measured directly with examining fingers. Thus, for clinical purposes, the obstetrical conjugate is estimated indirectly by subtracting 1.5 to 2 cm from the diagonal conjugate, which is determined by measuring the distance from the lowest margin of the symphysis to the sacral promontory  Transverse and Two oblique diameters The transverse diameter is constructed at right angles to the obstetrical conjugate and represents the greatest distance between the linea terminalis on either side It usually intersects the obstetrical conjugate at a point approximately 5 cm in front of the promontory and measures approximately 13 cm Each of the two oblique diameters extends from one sacroiliac synchondrosis to the contralateral iliopubic eminence. Each eminence is a minor elevation that marks the union site of the ilium and pubis. These oblique diameters average less than 13 cm  Midpelvis The midpelvis is measured at the level of the ischial spines, also called the midplane or plane of least pelvic dimensions During labor, the degree of fetal head descent into the true pelvis may be described by station, and the midpelvis and ischial spines serve to mark zero station The interspinous diameter is 10 cm or slightly greater, is usually the smallest pelvic diameter, and, in cases of obstructed labor, is particularly important. The anteroposterior diameter through the level of the ischial spines normally measures at least 11.5 cm.  The pelvic outlet The pelvic outlet consists of two approximately triangular areas whose boundaries mirror those of the perineal triangle They have a common base, which is a line drawn between the two ischial tuberosities. The apex of the posterior triangle is the tip of the sacrum, and the lateral boundaries are the sacrotuberous ligaments and the ischial tuberosities The anterior triangle is formed by the descending inferior rami of the pubic bones. These rami unite at an angle of 90 to 100 degrees to form a rounded arch under which the fetal head must pass  The pelvic outlet Clinically, three diameters of the pelvic outlet usually are described: 1. Anteroposterior 2. Transverse 3. Posterior sagittal Unless there is significant pelvic bony disease, the pelvic outlet seldom obstructs vaginal delivery  The four types of female pelvis Caldwell–Moloy classification The gynecoid pelvis is found in approximately 50% of all women and considered a true female pelvis The android pelvis is identified by a funnel shape. It is found in approximately 20% of women. The android pelvis has characteristics of male pelvis Evidence-based health care  Why Evidence Based Medicine? To improve quality of care through the identification and promotion of practices that work, and the elimination of those that are ineffective or harmful EBM promotes critical thinking It demands that the effectiveness of clinical interventions, the accuracy and precision of diagnostic tests, and the power of prognostic markers should be scrutinised and their usefulness proven It requires clinicians to be open minded and look for and try new methods that are scientifically proven to be effective and to discard methods shown to be ineffective or harmful Randomized studies and meta-analysis of obstetrics A meta-analysis is a statistical analysis that combines the results of multiple scientific studies Meta-analyses are a key component of evidence-based health care  Meta-analyses Meta-analyses offer several potential advantages: Provide a systematic and explicit method for synthesizing evidence, a quantitative overall estimate (and confidence intervals) derived from the individual studies, and early evidence as to the effectiveness of treatments, thus reducing the need for continued study Can address questions in specific subgroups that individual studies may not have examined  Legal issues in obstetrics Obstetrics is a specialty that is widely perceived to be associated with a high risk of litigation  Majority of obstetric litigation Missing structural abnormalities during obstetric ultrasound and failure to inform the patients of such abnormalities Intrapartum fetal distress Shoulder dystocia Complications of vaginal birth after caesarean section How to improve patient care and reduce medico- legal claims? Effective communication Team working Documentation Training and education Robust risk management strategies