Lucio Godina (March 8, 1908 – November 24, 1936) and Simplicio Godina (March 8, 1908 - December 8, 1936) were pygopagus conjoined twins from the island of Samar in the Philippines.

At the age of 21 they married Natividad and Victorina Matos, who were identical twins. They performed in various sideshow acts, including in an orchestra on Coney Island and in dance with their wives.

After Lucio died of rheumatic fever in New York City, doctors operated to separate him from Simplicio. Simplicio survived the operation, but died shortly thereafter due to spinal meningitis.

Joseph Banda and Luka Banda (born January 23, 1997, in Lusaka, Zambia) are twin brothers who used to be conjoined. They were born joined at the back of the skull and faced in opposite directions. In 1997, Dr. Ben Carson led a team of 50 Zambian and South African specialists to separate the 11-month-old twins in a 22-hour operation. They did not share any organs, but shared intricate blood vessels that flowed into each other's brains. In 2001, the twins were fitted with artificial skulls to permanently close their heads, and are neurologically normal. In an interview, Dr. Carson stated about the operation:

They are residing in a low-cost/high-density area of Lusaka called Chilenje South.

Ladan and Laleh Bijani (in Persian: ) (January 17, 1974 – July 8, 2003) were Iranian conjoined twin sisters. They were joined at the head and died immediately after their complicated surgical separation. Coincidentally, the twins were born 100 years to the day of the deaths of Chang and Eng Bunker, also conjoined twins, famously known as the "original" Siamese twins.

Sirenomelia, alternatively known as Mermaid syndrome, is a rare congenital deformity in which the legs are fused together, giving them the appearance of a mermaid's tail as the nickname suggests.

This condition is found in approximately one out of every 100,000 live births (about as rare as conjoined twins) and is usually fatal within a day or two of birth because of complications associated with abnormal kidney and urinary bladder development and function. More than half the cases of sirenomelia result in stillbirth and this condition is 100 times more likely to occur in identical twins than in single births or fraternal twins. It results from a failure of normal vascular supply from the lower aorta in utero. Maternal diabetes has been associated with caudal regression syndrome and sirenomelia, although a few sources question this association.

VACTERL-H is an expanded form of the VACTERL association that concludes that this diagnosis is a less severe form of sirenomelia. The disorder was formerly thought to be an extreme case of caudal regression syndrome; however, it was reclassified to be considered a separate condition.

"'Conjoined twins" are identical twins joined in utero. An extremely rare phenomenon, the occurrence is estimated to range from 1 in 49,000 births to 1 in 189,000 births, with a somewhat higher incidence in Southeast Asia and Africa. Approximately half are stillborn, and an additional one-third die within 24 hours. Most live births are female, with a ratio of 3:1.

Two contradicting theories exist to explain the origins of conjoined twins. The more generally accepted theory is "fission", in which the fertilized egg splits partially. The other theory, no longer believed to be the basis of conjoined twinning, is fusion, in which a fertilized egg completely separates, but stem cells (which search for similar cells) find like-stem cells on the other twin and fuse the twins together. Conjoined twins share a single common chorion, placenta, and amniotic sac, although these characteristics are not exclusive to conjoined twins as there are some monozygotic but non-conjoined twins who also share these structures in utero.

The most famous pair of conjoined twins was Chang and Eng Bunker (Thai: อิน-จัน, In-Chan) (1811–1874), Thai brothers born in Siam, now Thailand. They traveled with P.T. Barnum's circus for many years and were labeled as the Siamese twins. Chang and Eng were joined at the torso by a band of flesh, cartilage, and their fused livers. In modern times, they could have been easily separated. Due to the brothers' fame and the rarity of the condition, the term "Siamese twins" came to be used as a synonym for conjoined twins.

Very frequent signs

- Abnormal gastrointestinal tract

- Absent pectoral muscles

- Brachydactyly (Short fingers)

- Dextrocardia

- Diaphragmatic hernia/defect

- Humerus absent/abnormal

- Liver/biliary tract anomalies

- Maternal diabetes

- Oligodactyly/missing fingers

- Radius absent/abnormal

- Rhizomelic micromelia (relatively shorter proximal segment of the limbs compared to the middle and the distal segments)

- Sparsity or abnormality of axillary hair on affected side

- Syndactyly of fingers (webbing)

- Ulna absent/abnormal

- Upper limb asymmetry

- Abnormal rib

- Simian crease on affected side

Frequent signs

- Hypoplastic/absent nipples

- Scapula anomaly

Occasional signs

- Agenesis/hypoplasia of kidneys

- Encephalocele/exencephaly

- Abnormal morphology of hypothalamic-hypophyseal axis

- Abnormal function of hypothalamic-hypophyseal axis

- Microcephaly

- Preaxial polydactyly

- Ureteric anomalies (reflux/duplex system)

- Vertebral segmentation anomaly

Conjoined twins are typically classified by the point at which their bodies are joined. The most common types of conjoined twins are:

- Thoraco-omphalopagus (28% of cases): Two bodies fused from the upper chest to the lower chest. These twins usually share a heart, and may also share the liver or part of the digestive system.

- Thoracopagus (18.5%): Two bodies fused from the upper thorax to lower belly. The heart is always involved in these cases. As of 2015, separation of a genuinely shared heart has not offered survival to two twins; a designated twin may survive if allotted the heart, sacrificing the other twin.

- Omphalopagus (10%): Two bodies fused at the lower abdomen. Unlike thoracopagus, the heart is never involved in these cases; however, the twins often share a liver, digestive system, diaphragm and other organs.

- Parasitic twins (10%): Twins that are asymmetrically conjoined, resulting in one twin that is small, less formed, and dependent on the larger twin for survival.

- Craniopagus (6%): Fused skulls, but separate bodies. These twins can be conjoined at the back of the head, the front of the head, or the side of the head, but not on the face or the base of the skull.

Other less-common types of conjoined twins include:

- Syncephalus: One head with a single face but four ears, and two bodies.

- Cephalothoracopagus: Bodies fused in the head and thorax. In this type of twins, there are two faces facing in opposite directions, or sometimes a single face and an enlarged skull.

- Xiphopagus: Two bodies fused in the xiphoid cartilage, which is approximately from the navel to the lower breastbone. These twins almost never share any vital organs, with the exception of the liver. A famous example is Chang and Eng Bunker.

- Ischiopagus: Fused lower half of the two bodies, with spines conjoined end-to-end at a 180° angle. These twins have four arms; one, two, three or four legs; and typically one external set of genitalia and anus.

- Omphalo-Ischiopagus: Fused in a similar fashion as ischiopagus twins, but facing each other with a joined abdomen akin to omphalopagus. These twins have four arms, and two, three, or four legs.

- Parapagus: Fused side-by-side with a shared pelvis. Twins that are dithoracic parapagus are fused at the abdomen and pelvis, but not the thorax. Twins that are diprosopic parapagus have one trunk and two faces. Twins that are dicephalic parapagus have one trunk and two heads, and have two (dibrachius), three (tribrachius), or four (tetrabrachius) arms.

- Craniopagus parasiticus: Like craniopagus, but with a second bodiless head attached to the dominant head.

- Pygopagus (Iliopagus): Two bodies joined at the pelvis.

- Rachipagus: Twins joined along the dorsal aspect (back) of their bodies, with fusion of the vertebral arches and the soft tissue from the head to the buttocks

Anesthesia awareness, also referred to as accidental awareness during general anaesthesia (AAGA) or unintended intra-operative awareness, is a potential complication occurring during general anesthesia where the intended state of complete unconsciousness is not maintained throughout the whole procedure. It can occur either because of failure to deliver sufficient anesthetic medication to the patient's body, or because of individual patient factors that mean the patient is resistant to what would normally be an adequate dose of anesthetic medication.

Viscerotropic leishmaniasis is a systemic infection reported in soldiers fighting in Operation Desert Storm in Saudi Arabia.

Poland syndrome, named after British surgeon Alfred Poland, is a rare birth defect characterized by underdevelopment or absence of the chest muscle (pectoralis) on one side of the body, and usually also webbing of the fingers (cutaneous syndactyly) of the hand on the same side (the ipsilateral hand). In most affected individuals, the missing part is the large section of the muscle that normally attaches to the upper arm on one side and the breastbone (sternum) on the other. Other abnormalities may occur on the affected side of the torso. In some cases, additional muscles in the chest wall, side, and shoulder are missing or underdeveloped.

There may also be rib cage abnormalities, such as shortened ribs, and the ribs may be noticeable due to less fat under the skin (subcutaneous fat). Breast and nipple abnormalities may also occur, and underarm (axillary) hair is sometimes sparse or abnormally placed. In most cases, the abnormalities in the chest area do not cause health problems or affect movement. Poland syndrome most often affects the right side of the body, and occurs more often in males than in females.

It is usually considered a unilateral condition. Some have claimed that the term can be applied in bilateral presentation, but others recommend using alternate terminology in those cases.

Tachyphylaxis (Greek ταχύς, "tachys", "rapid", and φύλαξις, "phylaxis", "protection") is a medical term describing an acute, sudden decrease in response to a drug after its administration, i.e. a rapid and short-term onset of drug tolerance. It can occur after an initial dose or after a series of small doses. Increasing the dose of the drug may be able to restore the original response.

Only a few individuals who did not have fatal kidney and bladder complications are known to have survived beyond birth with this condition.

There are two states of consciousness that may be present:

- Awareness: That is, patients seem to be cognizant responding to commands but with no postoperative recall or memory of the events.

- Awareness and recall: That is, patients can recall events postoperatively, but were not necessarily conscious enough to respond to commands.

The incidence of a state with both responses in diverse degrees is also possible. The drugs that induce paralysis would also prevent responding to commands.

In the past, the use of terminology when describing parasitic twins has been somewhat inconsistent. By definition, a parasitic twin is joined to another twin in a certain anatomical location or position on the developed twin's body. The underdeveloped twin is termed the parasite, and the developed twin is termed the autosite. The autosite can have some abnormalities, as well. For the most part, however, it has developed enough that it can live on its own.

McGillivray syndrome is a very rare syndrome which is also known as a Craniosynostosis. It is characterized mainly by heart defects, skull and facial abnormalities and ambiguous genitalia. The symptoms of this syndrome are ventricular septal defect, patent ductus arteriosus, small jaw, undescended testes, and webbed fingers. Beside to these symptoms there are more symptoms which is related with bone structure and misshape.

McGillivray syndrome is a birth defect in which one or more of the joints between the bones of your baby's skull close prematurely, before your baby's brain is fully formed. When your baby has craniosynostosis, his or her brain cannot grow in its natural shape and the head is misshapen. It can affect one or more of the joints in your baby's skull. In some cases, craniosynostosis is associated with an underlying brain abnormality that prevents the brain from growing properly. Treating McGillivray usually involves surgery to separate the fused bones. If there is no underlying brain abnormality, the surgery allows baby’s brain to grow and develop in adequate space.

Exsanguination is the process of blood loss, to a degree sufficient to cause death. One does not have to lose all of one's blood to cause death. Depending upon the age, health, and fitness level of the individual, people can die from losing half to two-thirds of their blood; a loss of roughly one-third of the blood volume is considered very serious. Even a single deep cut can warrant suturing and hospitalization, especially if trauma, a vein or artery, or another comorbidity is involved. It is most commonly known as "bleeding to death" or colloquially as "bleeding out". The word itself originated from Latin: "ex" ("out of") and "sanguis" ("blood").

Only ten cases of craniopagus parasiticus have been reported in the medical research literature. Of those cases, only three have survived birth. The first case on record is that of Everard Home's Two-Headed Boy of Bengal, whose skull is preserved at the Hunterian Museum at the Royal Society of Surgeons.

Accessory pancreas is a rare condition in which small groups of pancreatic cells are separate from the pancreas. They may occur in the mesentery of the small intestine, the wall of the duodenum, the upper part of the jejunum, or more rarely, in the wall of the stomach, ileum, gallbladder or spleen. The condition was first described by Klob in 1859.

Accessory pancreas is a small cluster of pancreas cells detached from the pancreas and sometimes found in the wall of the stomach or intestines.

Your baby's skull has seven bones. Normally, these bones don't fuse until around age 2, giving your baby's brain time to grow. Joints called cranial sutures, made of strong, fibrous tissue, hold these bones together. In the front of your baby's skull, the sutures intersect in the large soft spot (fontanel) on the top of your baby's head. Normally, the sutures remain flexible until the bones fuse. The signs of craniosynostosis may not be noticeable at birth, but they become apparent during the first few months of your baby's life. The symptoms differs from types of synostosis. First of all there is Sagittal synostosis (scaphocephaly). Premature fusion of the suture at the top of the head (sagittal suture) forces the head to grow long and narrow, rather than wide. Scaphocephaly is the most common type of craniosynostosis. The other one is called Coronal synostosis (anterior plagiocephaly). Premature fusion of a coronal suture — one of the structures that run from each ear to the sagittal suture on top of the head — may force your baby's forehead to flatten on the affected side. It may also raise the eye socket and cause a deviated nose and slanted skull. The Bicoronal synostosis (brachycephaly). When both of the coronal sutures fuse prematurely, your baby may have a flat, elevated forehead and brow.

Symptoms include an enlargement in the size of the spleen, or a change from the spleen's original position to another location, usually in either other parts of the abdomen or into the pelvis. This ability to move to other locations is commonly attributed to the spleen's pedicle being abnormally long.

Physical factors may cause ischuria, constipation, as well as numerous spleen-related diseases such as hypersplenism, thrombocytopenia, and lymphoma. Blocking of the arteries and torsion in the spleen can also result in abdominal pain or swelling. However, lack of visible symptoms — except in incidents of abdominal pain — makes the disease difficult for doctors to diagnose, though medical imaging techniques such as medical ultrasonography, magnetic resonance imaging, or computed tomography can be used to confirm its occurrence.

Tachyphylaxis is characterized by the rate sensitivity: the response of the system depends on the rate with which a stimulus is presented. To be specific, a high-intensity prolonged stimulus or often-repeated stimulus may bring about a diminished response also known as desensitization.

Wandering spleen is most commonly diagnosed in young children as well as women between the ages of 20 and 40. Even so, the disease is very rare and fewer than 500 occurrences of the disease have been reported as of 2005, of which around 148 (including both children and adult cases) were documented to have been from between 1960 and 1992. Less than 0.5% of all splenectomies, surgical removal of the spleen, are performed due to having this disorder.

Characteristics of the disorder include the loss, weakening, or malformation of the ligaments that help to keep the spleen located in the upper left part of the abdomen. Though not a genetic disease, wandering spleen is often found at birth. It can occur in adults as the result of injuries and other similar conditions that cause the ligaments to weaken, such as connective tissue disease or pregnancy. Wandering spleen (splenoptosis) predisposes the spleen to complications such as torsion, splenic infarction, pancreatic necrosis and rarely pseudocyst formation.

In 1992, the youngest case of the literature of torsion of wandering spleen at two days of birth was reported in Lebanon, by Dr Edouard Sayad.

Exsanguination is a relatively uncommon cause of death in human beings. Traumatic injury can cause exsanguination if bleeding is not promptly controlled, and is the most common cause of death in military combat. Non-combat causes can include gunshot or stab wounds; motor vehicle crash injuries; suicide by severing arteries, typically those in the wrists; and partial or total limb amputation, such as via accidental contact with a circular or chain saw, or becoming entangled in operating machinery.

Patients can also develop catastrophic internal hemorrhages, such as from a bleeding peptic ulcer, postpartum bleeding or splenic hemorrhage, which can cause exsanguination without any external signs of distress. Another cause of exsanguination in the medical field is that of aneurysms. If a dissecting aortic aneurysm ruptures through the adventitia, massive hemorrhage and exsanguination can result in a matter of minutes.

Blunt force trauma to the liver, kidneys, and spleen can cause severe internal bleeding as well, though the abdominal cavity usually becomes visibly darkened as if bruised. Similarly, trauma to the lungs can cause bleeding out, though without medical attention, blood can fill the lungs causing the effect of drowning, or in the pleura causing suffocation, well before exsanguination would occur. In addition, serious trauma can cause tearing of major blood vessels without external trauma indicative of the damage.

Alcoholics and others with liver disease can also suffer from exsanguination. Thin-walled, normally low pressure dilated veins just below the lower esophageal mucosa called esophageal varices can become enlarged in conditions with portal hypertension. These may begin to bleed, which with the high pressure in the portal system can be fatal. The often causative impaired liver function also reduces the availability of clotting factors (many of which are made in the liver), making any rupture in vessels more likely to cause a fatal loss of blood.

Most people suffer from a form of fear of medical procedures during their life. There are many different aspects of this fear and not everyone has every part. Some of these parts include fear of surgery, fear of dental work and fear of doctors (involving fear of needles). These fears are often overlooked, but when a patient has one to the extreme it can be very damaging to their health.

Formally, medical fear is defined (by Steward and Steward, see Further reading) as "any experience that involves medical personnel or

procedures involved in the process of evaluating or modifying health status in traditional health care settings".

The spotty skin pigmentation and lentigines occur most commonly on the face, especially on the lips, eyelids, conjunctiva and oral mucosa. Cardiac myxomas may lead to embolic strokes and heart failure and may present with fever, joint pain, shortness of breath, diastolic rumble and tumor plop. Myxomas may also occur outside the heart, usually in the skin and breast. Endocrine tumors may manifest as disorders such as Cushing syndrome. The most common endocrine gland manifestation is an ACTH-independent Cushing's syndrome due to primary pigmented nodular adrenocortical disease (PPNAD).

The LAMB acronym refers to lentigines, atrial myxomas, and blue nevi. NAME refers to nevi, atrial myxoma, myxoid neurofibromas, and ephelides.

Testicular cancer, particularly Sertoli cell type, is associated with Carney syndrome. Thyroid and pancreas cancer may also occur.

Although J Aidan Carney also described Carney's triad it is entirely different.