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A parasitic twin (also known as an asymmetrical or unequal conjoined twin) is the result of the processes that produce vanishing twins and conjoined twins, and may represent a continuum between the two. Parasitic twins occur when a twin embryo begins developing in utero, but the pair does not fully separate, and one embryo maintains dominant development at the expense of the other. Unlike conjoined twins, one ceases development during gestation and is vestigial to a mostly fully-formed, otherwise healthy individual twin. The undeveloped twin is defined as parasitic, rather than conjoined, because it is incompletely formed or wholly dependent on the body functions of the complete fetus. The independent twin is called the autosite.
Breast reconstruction 3D Animation
on Friday, December 17, 2010
The primary part of the procedure can often be carried out immediately following the mastectomy. As with many other surgeries, patients with significant medical comorbidities (high blood pressure, obesity, diabetes) and smokers are higher-risk candidates. Surgeons may choose to perform delayed reconstruction to decrease this risk. Patients expected to receive external beam radiation as part of their adjuvant treatment are also commonly considered for delayed autologous reconstruction due to significantly higher complication rates with tissue expander-implant techniques in those patients. Breast reconstruction is a large undertaking that usually takes multiple operations. Sometimes these follow-up surgeries are spread out over weeks or months. If an implant is used, the individual runs the same risks and complications as those who use them for breast augmentation but has higher rates of capsular contracture (tightening or hardening of the scar tissue around the implant) and revisional surgeries. Outcomes based research on quality of life improvements and psychosocial benefits associated with breast reconstruction served as the stimulus in the United States for the 1998 Women's Health and Cancer Rights Act which mandated health care payer coverage for breast and nipple reconstruction, contralateral procedures to achieve symmetry, and treatment for the sequelae of mastectomy. This was followed in 2001 by additional legislation imposing penalties on noncompliant insurers. Similar provisions for coverage exist in most countries worldwide through national health care programs. There are many methods for breast reconstruction. The two most common are: * Tissue Expander - Breast implants This is the most common technique used in worldwide. The surgeon inserts a tissue expander, a temporary silastic implant, beneath a pocket under the pectoralis major muscle of the chest wall. The pectoral muscles may be released along its inferior edge to allow a larger, more supple pocket for the expander at the expense of thinner lower pole soft tissue coverage. The use of acellular human or animal dermal grafts have been described as an onlay patch to increase coverage of the implant when the pectoral muscle is released, which purports to improve both functional and aesthtic outcomes of implant-expander breast reconstruction. o In a process that can take weeks or months, saline solution is percutaneously injected to progressively expand the overlaying tissue. Once the expander has reached an acceptable size, it may be removed and replaced with a more permanent implant. Reconstruction of the areola and nipple are usually performed in a separate operation after the skin has stretched to its final size. * Flap reconstruction The second most common procedure uses tissue from other parts of the patient's body, such as the back, buttocks, thigh or abdomen. This procedure may be performed by leaving the donor tissue connected to the original site to retain its blood supply (the vessels are tunnelled beneath the skin surface to the new site) or it may be cut off and new blood supply may be connected. o The latissimus dorsi muscle flap is the donor tissue available on the back. It is a large flat muscle which can be employed without significant loss of function. It can be moved into the breast defect still attached to its blood supply under the arm pit (axilla). A latissimus flap is usually used to recruit soft-tissue coverage over an underlying implant. Enough volume can be recruited occasionally to reconstruct small breasts without an implant. o Abdominal flaps The abdominal flap for breast reconstruction is the TRAM flap or its technically distinct variants of microvascular "perforator flaps" like the DIEP/SIEP flaps. Both use the abdominal tissue between the umbilicus and the
Childbirth (also called labour, birth, partus or parturition) is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus. The process of normal human childbirth is categorized in three stages of labour: the shortening and dilation of the cervix, descent and birth of the infant, and birth of the placenta. In many cases, with increasing frequency, childbirth is achieved through caesarean section, the removal of the neonate through a surgical incision in the abdomen, rather than through vaginal birth. In the U.S. and Canada it represents nearly 1 in 3 (31.8%) and 1 in 4 (22.5%) of all childbirths, respectively.