- Meconium is the dark, tarry contents of the fetal gastrointestinal tract. Meconium passage at labor and delivery is common and not a sign of fetal distress unless it is accompanied by other ominous signs.
- Meconium release into the amniotic fluid is however considered a sign of intrauterine fetal distress. This can be caused by placental insufficiency, maternal hypertension, and preeclampsia, among other things.
- When meconium is freshly released, it is clumpy and oats in the amniotic fluid. Within hours, it distributes particulate matter throughout the sac. Macrophages in the fetal skin, mucus membranes, and the amniotic sac phagocytize the particles, giving a green cast to the tissues.
- After several days, the fluid is greenish-brown but clear, and the fetus and membranes are stained. After several weeks, the fetal skin and fluid will clear, but the amniotic membranes, fetal mucus membranes, and nail beds remain stained.
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- This 2D dissolve animation shows how this maneuver can release shoulder dystocia impaction and allow for delivery of the fetal shoulder.
- Each animation has pause and play buttons to allow for more interactivity during viewing.
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- The mandible, or lower jaw, is the bone that hinges to the skull and, together with the maxilla, forms the mouth.
- The mandibular nerve, the third and largest branch of the trigeminal nerve, runs along the mandible.
- The mandibular nerve has both sensory and motor functions. It divides into trunks and smaller branches to innervate the teeth and gums of the mandible, the lower lip and lower part of the face, and the muscles of mastication.
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- Mammography is an imaging technique which allows visualization of breast tissue. Fat, glandular tissue and ductal tissue have characteristic densities and patterns.
- Solid tumors are generally easier to see in older patients with larger amounts of fat within the breasts, but can be difficult to see in patients with “dense” breasts (young women and women with fibrocystic breasts).
- Approximately 75% of breast cancers can be seen on mammography, with the patient’s breast characteristics being the largest determining factor.
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- The male pelvis contains the bladder and rectum, along with the internal portions of the reproductive system: the prostate, seminal vesicles, and the intrapelvic portions of the ductal apparatus.
- Sperm is produced in the testes, which lie in the scrotal sac outside of the pelvis. The sperm travels up the spermatic duct and is stored in the seminal vesicles. At ejaculation, sperm is released along with prostatic fluid, both of which travel down the urethra.
- The urethra has three parts: the prostatic portion; the membranous portion which passes through the urogenital diaphragm, and the penile portion.
- The spermatic cord contains a venous plexus, the spermatic artery and the spermatic duct.
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- The main reason that preterm infants are considered high risk is because their lungs are immature.
- Lungs develop as the airways bud and branch into an anlage of mesenchymal cells. Since respiration requires oxygen and carbon dioxide to cross over two layers of tissue (alveolar wall and capillary wall), these relatively thick-walled airways in preterm babies permit little gas exchange. High-pressure ventilation is required to assist the infant, and this pressure frequently results in the development of chronic lung disease (bronchopulmonary dysplasia).
- In addition, there are too few alveoli present for efficient oxygen supply until 2-3 weeks prior to term. Lungs continue to grow and develop new alveoli for several years after birth.
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- The lumbar spine is composed of large, strong bones which must support the entire weight of the spine and head.
- The vertebral bodies are separated by fibrous discs which serve as shock absorbers. The discs have a fibrous ring (annulus fibrosis) and a gel-like center (nucleus pulposus).
- The spinal canal is formed by the pedicles, laminae, and the vertebral bodies and discs; the canal protects the distal portion of the axial nervous system, the cauda equina.
- The large transverse and spinous processes serve as support for the many paraspinous muscles which allow for the fine movement of the spine.
- The sacrum is the large, wedge-shaped bone forming the posterior part of the pelvic bowl, and is composed of fused vertebrae.
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- Analogous to the brachial plexus, the lumbosacral plexus is a series of nerve convergences and separations which ultimately combine into several large terminal nerves.
- Plexi form a protective mechanism in that if one nerve root is damaged, a particular muscle might be weakened, but function would not be completely lost.
- The terminal nerves in the legs generally follow the course of the deep vasculature.
- Terminal sensory nerves to the feet are particularly vulnerable to diabetes, resulting in peripheral diabetic neuropathy. This frequently contributes to foot infections and the need for amputation.
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- A common assumption is that a cancer may not have been diagnosed early enough to make a difference, with the assumption being that early diagnosis is always better.
- In reality, cancers are present for very long periods of time before they are diagnosable, and many have metastasized prior to the period in which they can be detected.
- The life span of more than 60% of cancer patients is essentially predetermined by the characteristics of the cancer itself. While a patient diagnosed earlier may live “longer” than one diagnosed later, both patients actually survive about the same length of time from the first cancer cell.
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- LASIK (laser-assisted in situ keratomileusis) is a popular type of refractive surgery, or surgery performed to improve visual acuity.
- In LASIK, an incision is made to lift up a partial thickness of the cornea, using a very sharp, thin microtome.
- Once the flap is formed, the stroma of the cornea is sculpted with the laser, under computer control. Many of the newer LASIK systems can also accommodate for any eye movement during surgery, using a tracking program.
- This procedure has a very high success rate with relatively few complications.
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- Cholecystitis, or inflammation of the gallbladder, is usually caused by gallstones blocking the cystic duct. Removal is usually performed via a laparoscopic approach, using an endoscope for visualization and hollow trocars holding the small instruments used for the surgery.
- The view through the laparoscope is transmitted to a video monitor, and the physician controls the progress by either looking directly through the scope or at the video display, depending on his or her preference and training.
- The overall complication rate for the laparoscopic procedure is about half that of the open procedure, although converting a laparoscopic procedure to an open one occurs approximately 4% of the time, usually because of difficulty in visualization.
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- After placement of the trocars, the gallbladder is grasped and retracted upward and outward. Adhesions, connective tissue, and the lesser omentum are divided from the neck of the gallbladder in a medial direction, to reveal a portion of the cystic duct.
- Clips are placed on the exposed cystic duct and an incision is made between the clips.
- The cystic artery is then located within the Triangle of Calot (formed by the planes of the lower border of the liver, the cystic duct, and the common hepatic duct), ligated and divided.
- The gallbladder is removed through one of the ports.
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- In the first stage of labor, the cervix must thin (efface) and open (dilate) to a diameter of about 10 cm (4 in) in order to allow the fetal head to pass through.
- Repeated uterine contractions pushing the fetal presenting part against the inside of the uterus cause the cervix to thin and open over time.
- The fetal presenting part is considered to be engaged when the lowest portion is at the level of the ischial spines; this is called the 0 station. Fetal movement down the birth canal is measured by positive stations, using a 0/+3 scale or a 0/+5 scale.
- The second stage of labor starts at full dilation of the cervix and is completed when the fetus is delivered. The third stage is the delivery of the placenta.
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- Intraventricular hemorrhage is bleeding within the cavities of the brain that normally hold clear cerebrospinal fluid (CSF). Such bleeding is frequently associated with pre-term delivery and can result in hydrocephalus and loss of brain tissue.
- Intraparenchymal bleeding is within the brain tissue itself and usually results from ruptured arteriovenous malformation (AVM), hemorrhage following ischemic infarction or hypertension.
- Subarachnoid hemorrhage usually results from a ruptured surface AVM or cerebral artery aneurysm.
- Subdural hemorrhage is the result of trauma leading to disruption of bridging veins between the dura and the brain.
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- Normal small bowel function is in the form of peristalsis, regular wave-like contractions of the smooth muscle within the wall of the bowel. Digested food materials (chyme) move through the small bowel, where intestinal villi absorb nutrients. These raw materials enter the bloodstream and are distributed throughout the body for growth and maintenance.
- Ileus is a temporary reduction or cessation of peristalsis, allowing fluid, chyme, and gases to accumulate. It is characterized by abdominal distension and discomfort; on x-ray, distended bowel loops with air/fluid levels can be seen. Bowel sounds are reduced or absent, and gas and stool are not passed.
- Ileus is a common sequela of abdominal or pelvic surgery, lasting hours to days. Symptoms are relieved by nasogastric suction to reduce pressure.
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- The largest joint in the body, the hip is composed of the large, round head of the femur which lies within the acetabulum or cup of the pelvis. Cartilage covers the articular surfaces, as in every other joint. There is a joint capsule and a number of muscles which cross and protect the joint and allow movement in a number of planes.
- The blood supply to the hip is relatively meager and easily disrupted with trauma.
- Since the entire weight of the body goes through this joint with every step, it is vulnerable to damage from use and is a common site for degenerative joint disease.
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- The normal heart is really two separate pumps working in tandem; there is no connection between the right and left sides in the normal post-fetal heart.
- The right heart receives de-oxygenated blood from the body, moving it from the right atrium to the right ventricle to the lungs via the pulmonary artery. Carbon dioxide is released and oxygen is picked up in the lungs.
- The left heart receives oxygenated blood from the lungs, moving it from the left atrium to the left ventricle, and from there to the aorta, which distributes it to the rest of the body.
- The ventricles are thick muscular chambers which move blood with each contraction; the average left ventricle contracts with a force of 120 mmHg.
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- Gastric bypass is performed to reduce the volume of food which the stomach can hold, and to reduce the amount of bowel available to absorb nutrients.
- There are several surgical variations; in this version, the stomach is divided and the small bowel is surgically joined to the small stomach remnant, bypassing the rest of the stomach. A second surgical anastomosis is made further down the length of the small bowel. No tissue is removed.
- The procedure can be performed either through a large abdominal incision or laparoscopically, using “band-aid” incisions. A lighted scope is inserted into the abdomen, as are several slender tubes. Instrumentation is then placed into the tubes and the procedure is performed under direct vision through the scope.
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- Forceps delivery is a type of operative vaginal delivery performed to help guide the baby out of the birth canal if the second stage of labor isn’t progressing or if fetal safety depends on immediate delivery.
- This 2D animation shows how this procedure is performed, showing that once the fetus has descended far enough down the birth canal, a health care provider applies the forceps to the fetal head.
- The forceps are then used to gently assist and guide the fetus out of the birth canal during uterine contractions. Forceps are not used between contractions.
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- Fetal heart rate is constantly varying from the baseline; this variability reflects a healthy fetal nervous system and cardiac responsiveness.
- These fluctuations are characterized as absent if there is no variation in the amplitude range, minimal if fluctuation is less than 5 bpm, moderate if fluctuation is 6 to 25 bpm, and marked if fluctuation is greater than 25 bpm.
- Absent variability indicates fetal academia but marked, moderate, and even minimal variation rules it out.
- Conditions like fetal hypoxia, congenital heart anomalies, and fetal tachycardia can cause a decrease in variability.
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- Heart muscle is supplied by the coronary arteries, not by the blood flowing through the heart.
- The major coronary vessels are the right coronary artery (RCA) and left main coronary artery (LCA), both of which come directly off of the aorta via the coronary ostia.
- The LCA divides into the left anterior descending artery(LAD) and circumflex artery.
- The RCA has no major branches and terminates as the posterior descending artery (PDA).
- There are may be variations in the anatomy.
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- The female pelvis contains the bladder, uterus, vagina, and rectum. The tissue between the vaginal and rectal openings is a tight collection of tendons from the pelvic floor muscles, the perineum. The entire region is called the vulva.
- The non-pregnant uterus is about the size of a small pear. It is a hollow muscular organ, its neck enclosed by a thick circular muscle known as the cervix.
- Urine is excreted from the kidneys via the ureters, which transport it to the bladder. It is then carried to the outside by the relatively short urethra.
- The ovaries release ova (eggs) each month to the uterus via the fallopian tubes; ovarian hormones are absorbed into the bloodstream.
- The organs are held in the pelvis by a number of ligaments connecting them to the pelvic walls.
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- Intubation is required when a patient has difficulty breathing and needs ventilatory assistance. A hollow tube is inserted into the trachea and held in place by a small inflated balloon. If intubation is required for more than a few weeks, a tracheostomy is used to replace it.
- Most endotracheal intubations are done using a laryngoscope, which holds the tongue and epiglottis out of the way while the health care provider inserts the ETT (endotracheal tube).
- Following ETT placement, the provider listens for bilateral breath sounds, watches for the chest to rise, and usually orders a portable chest x-ray to check ETT placement.
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- A tracing is made from electrical impulses traveling through the heart, tracking the way the heart muscle reacts to the conduction system.
- An electrical impulse is initiated at the sinoatrial node, passes through specialized neuromuscular fibers lying beneath the inner lining of the heart until it reaches the atrioventricular node; from there, it travels through the Bundle of His, into the bundle branches and the Purkinje fibers, stimulating ventricular contraction.
- Changes in tracings are evaluated by comparing them to normal and/or baseline tracings; a physician can get information about areas of heart damage, both acute and chronic.
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- Variable decelerations can occur at any time during or between contractions and are usually characterized by “shoulders” before and sometimes after the deceleration.
- The decelerations are usually “V” or “U”-shaped and return to baseline within two minutes or less.
- Variable decelerations are due to head or cord compression and are “treated” by changing the mother’s position and applying oxygen.
- Unless very deep (<60 bpm) for extended periods (>2 minutes or more), they are considered benign.
- Variable decelerations occur during the second stage of most labors, as the fetal head moves down the narrow vaginal canal and is compressed by a combination of the uterine contractions and the narrow vagina.
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- This technology, used in approximately 87% of all labors in the U.S., tracks the fetal heart function against uterine contractions.
- The normal fetal heart rate is approximately 120-160 beats per minute (bpm), although normal individual fetuses might be higher or lower than this range.
- Beat-to-beat variability is literally the changes of the fetal heart rate from beat to beat (short-term variability), and within 3-5 minute periods (long-term variability). Beat-to-beat variability decreases or disappears for 20-30 minute time periods as the fetus sleeps, but is present in most normal labors and represents the health of the fetal brainstem.
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- Late decelerations start at or after the peak of a contraction and are considered to be a sign of uteroplacental insufficiency.
- The depth of late decelerations is probably not as significant as their presence. If frequent, they can be a sign of fetal distress and an indication for prompt delivery.
- If late decelerations are accompanied by loss of beat-to-beat variability, it is generally considered an indication for urgent or emergent delivery, either by cesarean section or operative delivery (forceps or vacuum extraction), depending upon the state of the labor.
- The vast majority of fetuses with nonreassuring fetal heart tracings are completely normal.
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- Dermatomes are strips of skin which are supplied by the nerve roots. If there is numbness or pain along a dermatome, it is a sign of damage or irritation of a specific nerve root, where the root exits the spinal cord and vertebral column. This is known as radiculopathy.
- Soon after the cervical and lumbosacral nerves leave the cord, they join and separate several times (plexi) before reaching their target organs. Nerve fibers to a given muscle may come from several different nerve roots. The skin sensory supply, however, remains directly associated with the root alone.
- Radicular pain usually occurs with compression of the nerve in the foramen, the hole by which the nerve exits the spinal canal.
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- Degenerative joint disease is a result of normal activity and is found in most people as they get older; it develops more rapidly and more severely in the case of joint trauma.
- Articular surfaces are covered with glassy-smooth cartilage. As the cartilage disintegrates over time (chondromalacia), it flakes off until the bone is eventually exposed.
- If bone starts to rub against bone, it reacts by forming more bone in the form of osteophytes. This is a very painful condition and when severe enough, requires joint replacement.
- Degenerative joint disease is frequently called osteoarthritis; rheumatoid arthritis is an autoimmune disease with very different causes and a slightly different set of symptoms.
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- These potentially lethal blood clots usually form in the deep veins of the leg or in the pelvis. Those in the legs are usually painful, whereas those in the pelvis may be asymptomatic.
- The clots usually form in the valves of the larger veins, propagating upward toward the heart.
- Clots of any size can break off and travel with the blood flow through the inferior vena cava to the right side of the heart and to the lungs; the pulmonary vasculature acts like a sieve and clots get caught in the vessels as the vessels get smaller, causing loss of blood flow in those areas. These clots are known as pulmonary emboli if they reach the lungs.
- Conditions associated with DVT and PE include a history of leg trauma, cancer, surgery, venous stasis from illness, lack of exercise, clotting defects and others.
