USA Surgery Today

In the not too distant future it may be possible to adequately diagnose and treat a much broader array of genetic disease in the fetus. Molecular biology has experienced dramatic advances in the past several years with high-throughput techniques such as proteomics and DNA microarray technology. When coupled with information derived from the human genome project, it is conceivable that many if not most human genetic diseases will diagnosed from a miniscule sampling of fetal DNA. Currently, it is possible to detect the presence of nucleated fetal cells in the blood of pregnant woman. This could provide a ready source of fetal DNA for potential prenatal genetic screening. Much like the new knowledge of fetal anatomic disease gained through prenatal US, the human genome project and high-throughput screening technologies will provide new opportunities for molecular fetal therapy.

Hyponatremia is a common postoperative electrolyte disturbance and usually results from administration of hypotonic fluids or large volume resuscitation with lactated Ringer’s, which has a sodium concentration of 130 meq per L. Although the strict definition of hyponatremia is a serum sodium of less than 135 meq per L, symptoms are unlikely to be present unless the concentration is below 120 meq per L. However, symptoms may occur at higher serum sodium levels if the fall in sodium is more acute (less than 24 hours:Avapro). The most common symptoms are central nervous system irregularities, although cardiovascular and musculoskeletal symptoms may also occur. When the serum sodium is low, free water crosses the blood brain barrier and results in excess water in the brain parenchyma. Nausea, emesis, headache, seizures, lethargy, and even coma may ensue in the acute setting. Weakness and ataxia are more common in cases of chronic hyponatremia. Rapid correction of the serum electrolyte imbalance may actually exacerbate these symptoms. This is because rapid alterations in serum osmolality may occur before the slower correction in the brain parenchyma, and further cellular dehydration is a possible result. Thus, it is preferable to correct major serum sodium deficits over a 24- to 48-hour period unless serious symptoms are present.