A vanishing twin, also known as twin resorption, is a fetus in a multigestation pregnancy that dies in utero and is then partially or completely reabsorbed. In some instances, the dead twin is compressed into a flattened, parchment-like state known as fetus papyraceus.Vanishing twins occur in up to one of every eight multifetus pregnancies and may not even be known in most cases. "High resorption rates, which cannot be explained on the basis of the expected abortion rate, suggest intense fetal competition for space, nutrition, or other factors during early gestation, with frequent loss or resorption of the other twin(s). "In pregnancies achieved by in vitro fertilization, "it frequently happens that more than one amniotic sac can be seen in early pregnancy, whereas a few weeks later there is only one to be seen and the other has vanished." See also
Chimera (genetics)
Mosaicism
Parasitic twin

References
Further reading
External links

Vanishing twin at eMedicine.com
50 articles about vanishing twin phenomenon in PubMed
Blepharochalasis is an inflammation of the eyelid that is characterized by exacerbations and remissions of eyelid edema, which results in a stretching and subsequent atrophy of the eyelid tissue, leading to the formation of redundant folds over the lid margins. It typically affects only the upper eyelids, and may be unilateral as well as bilateral. Signs and symptoms
Complications
Complications of blepharochalasis may include conjunctival hyperemia (excessive blood flow through the moist tissues of the orbit), chemosis, entropion, ectropion, and ptosis. Causes
Blepharochalasis is idiopathic in most cases, i.e., the cause is unknown. Systemic conditions linked to blepharochalasis are renal agenesis, vertebral abnormalities, and congenital heart disease. Pathophysiology
Blepharochalasis results from recurrent bouts of painless eyelid swelling, each lasting for several days. This is thought to be a form of localized angioedema, or rapid accumulation of fluid in the tissues. Recurrent episodes lead to thin and atrophic skin. Damage to the levator palpebrae superioris muscle causes ptosis, or drooping of the eyelid, when the muscle can no longer hold the eyelid up. Diagnosis
Differential diagnosis
Dermatochalasis is sometimes confused with blepharochalasis, but these are two different conditions. Treatment
The following procedures have been described for blepharochalasis:
External levator aponeurosis tuck
Blepharoplasty
Lateral canthoplasty
Dermis fat graftsThese are used to correct atrophic blepharochalasis after the syndrome has run its course. Epidemiology
It is encountered more commonly in younger rather than older individuals

References


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