• Cataract Surgery

    • The lens opacifies with age or after trauma. When vision is sufficiently affected, the cataract can be surgically removed and replaced with an artificial intraocular lens.
    • The cornea is lifted from an incision in the blue-grey line surrounding the iris, and the anterior surface of the lens is opened. The nucleus of the lens is removed, leaving the posterior capsule of the lens in position.
    • The intraocular lens is then placed within the capsule and fixed into position. Laser treatments are often needed post-operatively to clear the posterior capsule.
    • This procedure is one of the safest and most common surgical procedures performed today, with a very low rate of complications.
  • Cervical Anatomy

    • The cervix is the circular muscle at the base of the uterus; it makes up the top of the vagina.
    • The cervical canal passes through the cervix and allows blood from menstruation and a fetus to pass from the uterus into the vagina.
    • During a pap smear, a screening test for cervical cancer, cells are scraped from the opening of the cervix and examined under a microscope for abnormality.
    • The transformation zone is the area where the mucus secreting columnar cells of the endocervix meet the squamous cells of the ectocervix. Most squamous cell carcinomas and dysplasias are found here.
  • Cervical Spine

    • The 7 vertebrae of the cervical spine help support the skull and protect the spinal cord as it exits the cranium to pass downward through the spinal canal.
    • The transverse processes each have a small hole through which the vertebral arteries pass to join to form the basilar artery supplying the posterior and deep portions of the brain and brainstem.
    • The cervical nerve roots form the brachial plexus which supplies sensation and movement to the upper extremities.
    • Degenerative joint disease and disc disease are very common in the cervical spine, leading to arm and hand pain and dysfunction requiring decompression and sometimes fusion.
  • Cholangiography

    • Performed during surgery for gallbladder removal, this is an effective intraoperative radiographic test to look for either blockage or leakage in the biliary tree.
    • This test may be performed prior to removing the gallbladder, or at any time a problem is suspected. A tiny catheter is threaded through a small incision in the cystic duct. Dye is injected into the biliary tract and x-rays are taken, allowing the surgeon to see which ducts are patent. Voids represent stones or tumors, and extravasation represents a leak in the system.
    • While this test is very reliable in the case of a retained stone or suspected damage, the outcome in patients having routine intraoperative cholangiography without apparent complication is the same as those in whom the test was not performed.
  • Coronary Artery Anatomy

    • Right heart dominance: the posterior portion of the interventricular septum is supplied by the posterior descending branch of the right coronary artery.
    • Left heart dominance: the entire septum is supplied by branches of the left anterior descending artery; an obstruction in that vessel may lead to loss of the entire septum, an often fatal event. The posterior descending artery is derived from a branch of the circumflex artery instead of from the RCA.
  • Decubitus Ulcer Causes

    • Decubitus ulcers are common in debilitated patients, particularly the aged who have thinner skin and subcutaneous tissue that is more susceptible to compression injury.
    • Patients with limited mobility (from injury, sickness, or neurologic disorders, etc.), poor nutritional intake, conditions affecting perfusion and oxygenation of tissues (like diabetes, cardiovascular disease, heart failure, etc.), skin moisture due to incontinence, and advanced age are particularly vulnerable.
    • These ulcers are often multifactorial, making them difficult to prevent and even more difficult to heal in at-risk patients.
  • Decubitus Ulcer Formation

    • Pressure ulcers are a localized injury to the skin and/or underlying tissue, usually over a bony prominence, that occur as a result of pressure, shear, and/or friction.
    • Stage I decubitus ulcers manifest as a non-blanchable area of skin redness, which then progresses to a partial thickness wound in Stage II, and further to full thickness skin loss in Stage III. Stage IV decubiti involve full thickness tissue loss with exposed bone, tendon, or muscle with sloughing, undermining, and tunneling. These ulcers can extend into muscle and/or supporting structures making osteomyelitis and sepsis a concern.
    • Decubitus ulcers are associated with an increased morbidity and mortality, and healing can be difficult as debilitated patients who form them usually have widespread vascular disease, nutritional de cits, and/or oxygenation/perfusion difficulties.
  • Deep Tissue Injury

    • Deep tissue injuries can have the same outward appearance as decubitus ulcers, but the underlying etiology is different. These injuries happen and progress quickly.
    • The mechanism of this injury is pressure to the skin and soft tissue, within a short period of time, that compromises tissue perfusion and results in ischemia and damage to the deeper subcutaneous tissues.
    • The initial injury is not visible on the surface of the skin and only manifests later as the underlying tissue starts to necrose, first forming what appears to be a bruise before progressing to an external/visible skin wound.
    • This type of wound evolves upward towards the skin as well as deeper, so once the external wound becomes apparent, it is frequently already a deep injury often with the appearance of a Stage 3–4 decubitus ulcer.
  • Deep Vein Thrombosis

    • 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.
  • Degenerative Joint Disease

    • 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.
  • Dermatomes

    • 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.
  • EFM (Late Decelerations)

    • 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.
  • EFM (Normal Strip)

    • 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.
  • EFM (Variable Decelerations)

    • 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.
  • Electrocardiography

    • 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.
  • Endotracheal Intubation

    • 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.
  • Female Pelvis

    • 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.
  • Fetal/Neonatal Circulation

    • 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.
  • FHR Variability Categories

    • 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.
    • 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.
  • Gastric Bypass

    • 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.
  • Heart Function

    • 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.
  • Hip Anatomy

    • 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.
  • Ileus

    • 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.
  • Intracranial Hemorrhage

    • 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.
  • Labor & Delivery

    • 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.
  • Lap Chole: Procedure

    • 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.
  • Lap Chole: Surgical Set-up

    • 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.
  • LASIK Procedure

    • 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.
  • Lead-Time Bias

    • 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.

Go to Top