Persius/hicric huggingface dataset:
Placenta accreta

# Overview
Placenta accreta is a severe obstetric complication involving an abnormal superficial attachment of the placenta to the myometrium (the middle layer of the uterine wall). There are three forms of placenta accreta, distinguishable by the depth of penetration.
The placenta usually detaches from the uterine wall relatively easily, but women that encounter placenta accreta during childbirth are at great risk of obstetrical hemorrhage during its removal. This commonly requires surgery to stem the bleeding and fully remove the placenta, and in severe forms can often lead to a hysterectomy or be fatal.
Placenta accreta affects approximately 1 in 2,500 pregnancies.

# Classification
The most common form of placenta accreta is an invasion of the myometrium which does not penetrate the entire thickness of the muscle. This form of the condition accounts for around 75-78% of all cases, and has no name other than placenta accreta.
There are two further variants of the condition that are known by specific names and are defined by the depth of their attachment to uterine wall. Placenta increta occurs when the placenta further extends into the myometrium and happens in around 17% of all cases. Placenta percreta, the worst form of the condition and occurring in 5-7% of cases, is when the placenta penetrates the entire myometrium to the uterine serosa (invades through entire uterine wall).  This variant can lead to the placenta attaching to other organs such as the rectum or bladder.

# Risk Factors
The condition affects around 10% of cases of placenta praevia, and is increased in incidence by the presence of scar tissue from a past caesarean section. A thin decidua can also be a contributing factor to such trophoblastic invasion. Some studies suggest that the rate of incidence is higher when the fetus is female.

# Diagnosis
Placenta accreta is very rarely recognized before birth, and is very difficult to diagnose. While it can lead to some vaginal bleeding during the third trimester, this is more commonly associated with the factors leading to the condition. In some cases, the second trimester can see elevated maternal serum alpha-fetoprotein levels, though this is also an indicator of many other conditions.
Pleural fibrosis
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Pleural fibrosis is a thickening of the outer layer of either one or both lungs.

# Causes

## Life Threatening Causes
Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

## Common Causes

## Causes by Organ System

## Causes in Alphabetical Order

# Diagnostic Findings
- Apical cap thickening
- Blunting of costophrenic angle
- Diffuse haziness
- Lines not corresponding to fissures
- Loss of lung volume
- No shift of fluid in lateral decubitus
Plummer syndrome
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Plummer syndrome is a condition that can occur when a hyper-functioning nodule develops within a longstanding goiter. The result is hyperthyroidism, without the opthalmologic effects of other conditions  with increased levels of thyroid hormones like Grave's disease. These toxic multi-nodular goiters are most common in women over the age of 60.
Pneumoperitoneum

# Overview
Pneumoperitoneum is air or gas in the abdominal (peritoneal) cavity, often seen on x-ray, but small amounts are often missed and CT is nowadays regarded as a criterion standard in the assessment of a pneumoperitoneum..

# Causes
The most common cause is a perforated abdominal viscus, generally a perforated ulcer, although any part of the bowel may perforate from a benign ulcer, tumor or trauma. A perforated appendix seldom causes a pneumoperitoneum. A pneumoperitoneum is deliberately created by the surgical team in order to perform laparoscopic surgery. This is achieved by insufflating the abdomen with carbon dioxide.
- Perforated peptic ulcer
- Bowel obstruction
- Ruptured diverticulum
- Penetrating trauma
- Ruptured inflammatory bowel disease (e.g. megacolon)
- Necrotising enterocolitis/Pneumatosis coli
- Ischemic bowel
- Steroids
- After laparotomy
- After laparoscopy
- Break down of a surgical anastomosis
- Bowel injury after endoscopy
- Peritoneal dialysis
- Vaginal insufflation (air enters via the fallopian tubes, e.g. water-skiing, oral sex)
- Colonic or peritoneal infection
- From chest (e.g. bronchopleural fistula)
Subphrenic abscess, bowel interposed between diaphragm and liver (Chilaiditi syndrome), and linear atelectasis at the base of the lungs can simulate free air under the diaphragm on a chest x-ray.

# Diagnosis

## Chest X-ray
Plain film signs of pneumoperitoneum
- Rigler's sign (gas outlining both mucosal and serosal surfaces of bowel wall)
- Falciform ligament sign (gas outlining the falciform ligament)
- Football sign (gas outlining the peritoneal cavity)
- 2 days post exploratory laporatomy patient#1 Image courtesy of RadsWiki and copylefted
- 2 days post exploratory laporatomy patient#1 Image courtesy of RadsWiki and copylefted
- Rigler's sign patient#2 Image courtesy of RadsWiki and copylefted
- Rigler's sign patient#2 Image courtesy of RadsWiki and copylefted
- Rigler's sign patient#2 Image courtesy of RadsWiki and copylefted
- patient#3 Image courtesy of RadsWiki and copylefted
- patient#3 Image courtesy of RadsWiki and copylefted
- patient#3 Image courtesy of RadsWiki and copylefted
- Large pneumoperitoneum after indomethicin treatment patient#4 Image courtesy of RadsWiki and copylefted
- Large pneumoperitoneum after indomethicin treatment patient#4 Image courtesy of RadsWiki and copylefted

## CT
CT can visualize quantities as small as 5 cm3 of air or gas.
- Rigler's sign patient#2 Image courtesy of RadsWiki and copylefted
- Rigler's sign patient#2 Image courtesy of RadsWiki and copylefted
Pontine arteries
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# Overview
The pontine arteries are a number of small vessels which come off at right angles from either side of the basilar artery and supply the pons and adjacent parts of the brain.
Branches of basilar artery - 
The basilar artery extends from the lower to the upper border of the pons. It lies in the median groove under the cover of arachnoid membrane.It divides into following branches on either side- 
Pontine artery 
Anterior inferior cerebellar artery (AICA)
Superior Cerebellar artery (SCA)
Posterior cerebral artery 
Internal auditory artery
Perforators - 
The small branches of the basilar artery are also known as perforators and this peroforating arteries can be classified into three subgroups : 
(i) rostral (mesencephalic perforating arteries, distal to the SCA); 
(ii) middle (pontine perforating arteries, between the SCA and AICA); 
(iii) caudal (proximal to the AICA).
There are between two and five rostral BA perforators, which have an average diameter of 250 m; the caudal perforators vary in diameter from 80 to 600 m. The midbasilar artery gives rise to between five and nine perforators with a diameter ranging from 210 to 940 m, which originate directly from the BA or from a common trunk linked to the superolateral or inferolateral pontine artery. The middle basilar perforator includes the pontomedullary artery, the long pontine artery/circumferential artery, and the anterolateral vessels.
The knowledge of this perforators is important to define the type of aneurysm according to the location of the perforating parent artery.
References:

# Additional images
- The arteries of the base of the brain.
Popliteal artery
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In human anatomy, the popliteal artery is defined as the extension of the femoral artery after passing through the adductor canal and adductor hiatus above the knee.  The termination of the popliteal artery is its bifurcation into the anterior tibial artery and posterior tibial artery.
The popliteal artery, through numerous smaller branches, supplies blood to the knee joint and muscles in the thigh and calf.  It is accompanied, along its length, by the popliteal vein.

# Branches
The branches of the popliteal artery are:
- anterior tibial artery
- posterior tibial artery
- sural artery
- medial superior genicular artery
- lateral superior genicular artery
- middle genicular artery
- lateral inferior genicular artery
- medial inferior genicular artery

## Tibial-fibular trunk
The fibular artery typically arises from the posterior tibial artery. Therefore, the posterior tibial artery proximal to the fibular artery origin is sometimes called the tibial-peroneal trunk or tibial-fibular trunk and it could be said that the popliteal artery bifurates into the tibial-fibular trunk and anterior tibial artery.

# Embryology
Embryologically, the popliteal artery is derived from the fetal sciatic artery, which is distinct from the femoral artery.

# Pulse
Its pulse can be palpated behind the knee, but is generally more challenging to find than other arteries of the leg.

# Additional images
- The popliteal, posterior tibial, and peroneal arteries.
Post viral cough
Post-viral Cough is a lingering cough experienced following a viral respiratory tract infection usually a common cold or flu and lasting more than eight weeks.
Post-viral cough is a clinically recognized condition represented within the European medical literature but is not mentioned in studies from America. 
Patients usually experience repeated episodes of post-viral cough. The heightened sensitivity in the respiratory tract is demonstrated by inhalation cough challenge.

# Cause
One possible cause for post-viral cough is that the receptors that are responsible for stimulating the cough during the respiratory tract infection continue to do so after the virus has disappeared, up-regulated by respiratory tract infection.

# Differential Diagnosis of Post viral cough

# Treatment
Post viral cough can be resistant to treatment. Inhaled steroids may work in some patients. Post-viral cough is usually treated the same way as a viral cough.
Postmortem spasm
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Sometimes, after an organism has died, small movements of the limbs (a twitch of a finger or even a whole leg moving) can be observed.  This phenomenon, known as postmortem spasm, can be observed in human cadavers as well as smaller organisms that have died.
Postprandial dip
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In medicine and specifically endocrinology, postprandial dip is a term used to refer to mild hypoglycemia occurring after ingestion of a heavy meal.
The dip is caused by a drop in blood glucose resulting from the body's own normal insulin secretion, which in turn is a respone to the glucose load represented by the meal.  It is often asymptomatic, but in some individuals it can produce drowsiness, leading to a postprandial nap.
While postprandial dip is usually physiological after a generous meal, a very sharp or sustained drop in blood glucose may be associated with a disorder of glucose metabolism.
Potassium iodate
Potassium iodate (KIO3) is a chemical compound.  It is sometimes used in radiation treatment, as it can replace radioactive iodine from the thyroid.  See potassium iodide for more information on this use.
Like potassium bromate, potassium iodate is occasionally used as a maturing agent in baking.
Potassium iodate is an oxidizing agent and as such it can cause fires if in contact with combustible materials or reducing agents.  It can be prepared by reacting a potassium-containing base such as potassium hydroxide with iodic acid, for example:
HIO3 + KOH  KIO3 + H2O
It can also be prepared by adding iodine to a hot, concentrated solution of potassium hydroxide.
3 I2 + 6 KOH  KIO3 + 5 KI + 3 H2O
Conditions/substances to avoid include: heat, shock, friction, combustible materials, reducing materials, aluminum, organic compounds, carbon, hydrogen peroxide and sulfides.

# Use
Potassium iodate is used for iodination of table salt, because iodide can be oxidized to iodine under wet conditions by oxygen. To prevent this US companies add thiosulfates or other antioxidants to the potassium iodide, while in some other countries potassium iodate is used as source for iodine.
Pourbaix diagram
In chemistry, a Pourbaix diagram, also known as a potential/pH diagram, maps out possible stable (equilibrium) phases of an aqueous electrochemical system.  Predominant ion boundaries are represented by lines. As such a Pourbaix diagram can be read much like a standard phase diagram with a different set of axes.
The diagrams are named after Marcel Pourbaix (19041998), the Russian-born chemist who invented them.
Pourbaix Diagrams are also known as Eh-pH diagrams due to the labeling of the two axes. 
The vertical axis is labeled Eh for the voltage potential with respect to the standard hydrogen electrode (SHE) as calculated by the Nernst equation. The "h" stands for Hydrogen, although other standards may be used.
The horizontal axis is labeled pH for the -log function of the  H+ ion concentration.
While such diagrams can be drawn for any chemical system, it is important to note that the addition of a metal binding agent (ligand) will often modify the diagram. For instance, carbonate has a great effect upon the diagram for uranium.
In addition, temperature and concentration of solvated ions in solution will shift the equilibrium lines in accordance with the Nernst Equation.
A simplified Pourbaix diagram indicates regions of "Immunity", "Corrosion" and "Passivity", instead of the stable species.
Prathap C. Reddy
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Dr. Pratap C. Reddy is a doctor and businessman who founded the first corporate chain of hospitals in India, the Apollo Hospitals Group. He is the Executive Chairman of the company.
A trained cardiologist with international experience, Dr. Reddy worked at the Missouri State Chest Hospital, where he headed several research programs. The absence of world-class medical facilities in India spurred him to set up the first Apollo Hospital in Chennai in 1983, at a time when private healthcare institutions were virtually unknown in India. Over the years, Dr. Reddy has been able to attract the best medical talent to India including doctors from hospitals in the US and UK. He has also been instrumental in bringing several regulatory changes that relate to licensing, ceasing of import restrictions, permission for organ transplants, etc. Dr. Reddys pioneering approach and tireless efforts have contributed significantly to the emergence of the private healthcare sector in India. For his contributions, Dr. Reddy was awarded the Padma Bhushan in 1991.

# Further reading
- Exclusive Interview with Dr. Pratap C. Reddy, PRIU, Government of Sri Lanka, June 5, 2002, accessed at  Nov 11, 2006
- Sanjiv Shankaran, Tremendous potential in managing hospitals, Business Line (The Hindu), February 11, 2001 accessed at  Nov 11, 2006
Precordial thump

# Overview
A precordial thump is a medical procedure used in the initial response to a witnessed cardiac arrest when no defibrillator is immediately available.  It can be used as a small part of the provision of advanced cardiac life support (ACLS). About 25% of patients in cardiac arrest who received a thump on the precordium regain cardiac function (Scherf and Bornemann:, 1960)

# Technique
To perform a precordial thump, a highly trained provider such as a paramedic or physician strikes a single very carefully aimed blow with the fist to the center of the patient's sternum.  The intent is to possibly interrupt a life threatening rhythm. The precordial thump is thought to produce an electrical depolarization of 2 to 5 joules. However, the thump is effective only if used at the onset of ventricular fibrillation or pulseless ventricular tachycardia and so should be used only when the arrest is witnessed or monitored. There is no evidence that the precordial thump improves recovery in unwitnessed cardiac arrest.
A precordial thump may be given just once. While the odds of success are poor, if a precordial thump is done properly, little time is lost.  The provider will immediately continue with other ACLS skills, or CPR if the needed ACLS drugs and equipment (such as a defibrillator) are unavailable.
The performance of a precordial thump is outside the scope of first aid and requires at minimum training in advanced cardiac life support. ACLS is performed primarily by physicians, paramedics and nurses with advanced training in emergency care.

# Natural History, Complications and Prognosis

## Natural History
Doctors Jack Pennington and Bernard Lown's cardiology group at Harvard University are credited with formalizing this technique in the medical literature. They published their report in the New England Journal of Medicine in the early 1970s.  Doctors. Richard S. Crampton and George Craddock, cardiologists at the University of Virginia helped to promote the paramedic use of chest thump through a curious accident. In 1970, the Charlottesville-Albemarle Rescue Squad (VA) was transporting a patient with an unstable cardiac rhythm in what was then called a Mobile Coronary Care Unit. When the vehicle inadvertently hit a speed bump in a shopping center parking lot, the patient's normal heart rhythm was restored. Further research confirmed that chest thumping patients with life-threatening arrhythmias could save lives.

## Complications
The use of the precordial thump technique has sometimes been shown in movies and television, usually in passing without any explanation.  Untrained laypersons have been known to attempt it and sometimes cause additional injury to the patient as the blow must be carefully aimed. Commotio cordis, cardiac arrest caused by blunt trauma to the heart, may ensue if a precordial thump is applied with a wrong timing.

# Related Chapters
- Precordial examination
- Commotio cordis
- Advanced cardiac life support
Pretzel Syndrome

# Overview
Pretzel syndrome is a rare disorder characterized by skeletal deformity, malformation of the brain (with accompanying seizures), electrolyte imbalances, and variable malformations of the heart and other organs.

# Historical Perspective
Pretzel syndrome, is named so by the families for the characteristic body posture adopted by many affected children.

# Pathophysiology

## Genetics
It is a single gene disorder but it is complex in its mechanics.The defective gene is called LYK5. It has a complicated function that is only partly understood. The LYK5 gene product is part of a chemical relay or messaging system that controls the growth and function of many cells in the body.
In Pretzel syndrome, part of the LYK5 gene is missing, which leads to a complete loss of this signaling function. The LYK5 gene has an important role in normal organ development. Defective organ development that begins during the earliest stages of pregnancy is not treatable and leads to a variety of medical problems throughout life.

# Diagnosis

## Symptoms
- In affected children studied, the first signs of Pretzel syndrome began during gestation: 80% of mothers had polyhydramnios, extra amniotic fluid around the affected baby.
- All mothers also had preterm labor starting anywhere from 25-38 weeks gestation. The brain was large and malformed in all affected children.
- The nerve cells were not positioned properly and probably did not make normal connections with other nerve cells. As a result,seizures began early in life and were often difficult to treat.
- Mental development was severely delayed.
- In 20-30% of affected children, there was a buildup of calcium deposits in the kidneys, which then lost the ability to conserve water for the body. This condition, called diabetes insipidus, causes children to urinate frequently.

## Physical Examination

### Eyes
- Like other muscles of the body, those that controlled the eyes were also weak, and about 40% of affected children had strabismus or lazy eye.

### Heart
Anatomical defect in heart typically does not cause symptoms of heart failure early in life, but can become problematic later in childhood.

### Extremities
- The muscles were thin and weaker than normal. The combination of low muscle tone and abnormal connective tissue resulted in very flexible joints and allowed children to twist themselves into unusual pretzel-like postures.

## MRI
- MRI studies showed extra fluid around the brain, or hydrocephalus.

# Treatment
Although the organ defects caused by LYK5 deficiency can not be prevented or reversed, Pretzel syndrome can nonetheless be treated by recognizing problems such as seizures, strabismus, diabetes insipidus, and heart defects, and treating these problems appropriately to optimize the health and well-being of the child.
- Children with strabismus should be treated by a pediatric eye doctor to prevent permanent loss of vision.
- Children with diabetes insipidus should be allowed to drink freely to prevent severe dehydration.