1.	Preparation of the placenta
<ol>
<li>The placenta should be acquired from the delivery room as soon as possible after delivery to minimize clot formation, desiccation and overall deterioration of the tissue.</li>
<li>Care should be taken to ensure that the placenta is not exposed to formalin or other fixatives.</li>
<li>Standard BSL2 precautions for human tissue should be maintained and personnel should wear a mask, gown, gloves and shoe covers.</li>
<li>Place the placenta in a large plastic or metal bowl that has p...

<ol>
	<li>Rand, L., Lee, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complicated+monochorionic+twin+pregnancies:+updates+in+fetal+diagnosis+and+treatment.">Complicated monochorionic twin pregnancies: updates in fetal diagnosis and treatment.</a> Clin Perinatol. 36, 417-430 (2009).</li><li>Sebire, N., Talbert, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Twin-to-twin+transfusion+syndrome+results+from+dynamic+asymmetrical+reduction+in+placental+anastomoses:+a+hypothesis.">Twin-to-twin transfusion syndrome results from dynamic asymmetrical reduction in placental anastomoses: a hypothesis.</a> in Placenta. , (2001).</li><li>Machin, G. A., Keith, L. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> An atlas of multiple pregnancy: biology and pathology. , (1999).</li><li>Machin, G. A., Feldstein, V. A., van Gemert, M. J., Keith, L. G., Hecher, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Doppler+sonographic+demonstration+of+arterio-venous+anastomosis+in+monochorionic+twin+gestation.">Doppler sonographic demonstration of arterio-venous anastomosis in monochorionic twin gestation.</a> Ultrasound Obstet Gynecol. 16, 214-217 (2000).</li><li>Denbow, M. L., Cox, P., Taylor, M., Hammal, D. M., Fisk, N. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Placental+angioarchitecture+in+monochorionic+twin+pregnancies:+Relationship+to+fetal+growth,+fetofetal+transfusion+syndrome,+and+pregnancy+outcome.">Placental angioarchitecture in monochorionic twin pregnancies: Relationship to fetal growth, fetofetal transfusion syndrome, and pregnancy outcome.</a> American Journal of Obstetrics and Gynecology. 182, 417-426 (2000).</li><li>Taylor, M. J. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Doppler+detection+of+arterio-arterial+anastomoses+in+monochorionic+twins:+feasibility+and+clinical+application.">Doppler detection of arterio-arterial anastomoses in monochorionic twins: feasibility and clinical application.</a> Human Reproduction. 15, 1632-1636 (2000).</li><li>Berm&#250;dez, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Placental+types+and+twin-twin+transfusion+syndrome.">Placental types and twin-twin transfusion syndrome.</a> American Journal of Obstetrics and Gynecology. 187, 489-494 (2002).</li><li>Lewi, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intertwin+anastomoses+in+monochorionic+placentas+after+fetoscopic+laser+coagulation+for+twin-to-twin+transfusion+syndrome:+is+there+more+than+meets+the+eye.">Intertwin anastomoses in monochorionic placentas after fetoscopic laser coagulation for twin-to-twin transfusion syndrome: is there more than meets the eye.</a> Am J Obstet Gynecol. 194, 790-795 (2006).</li><li>Wee, L. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterisation+of+deep+arterio-venous+anastomoses+within+monochorionic+placentae+by+vascular+casting.">Characterisation of deep arterio-venous anastomoses within monochorionic placentae by vascular casting.</a> Placenta. 26, 19-24 (2005).</li><li>Paepe, M. E. D. e., Burke, S., Luks, F. I., Pinar, H., Singer, D. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Demonstration+of+placental+vascular+anatomy+in+monochorionic+twin+gestations.">Demonstration of placental vascular anatomy in monochorionic twin gestations.</a> Pediatr Dev Pathol. 5, 37-44 (2002).</li></ol>

Vascular mapping of MC twin placentas by dye injection is a valuable procedure for assessing complicated, clinically-treated cases and for further enhancing our understanding of MC twinning. Coordination with the obstetric team to ensure expeditious acquisition of an intact placental specimen is crucial. Desiccation or prolonged storage of the tissue prior to injection may lead to vessel injury and extravasation of dye. Fixation of the placenta must be avoided, because cross-linked blood clots will block perfusion of int...

<table border="1">
	<tbody>
		<tr>
			<th>Name of the reagent	</th>
			<th>Company	</th>
			<th>Catalogue number	</th>
			<th>Comments(optional)</th>
		</tr>
		<tr>
			<td>Perforated plastic bowl</td>
			<td>QuickMedical
			Medical Equipment and Supplies</td>
			<td>Polarware PA75</td>
			<td>Perforations can be made with a drill</td>
		</tr>
		<tr>
			<td>Stainless steel bowl</td>
			<td>Narang Medical Limited</td>
			<td>HH517</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Normal Saline</td>
			<td>Fisher</td>
			<td>50983204</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>0.6-1.9 mm ID polyethylene tubing		</td>
			<td>Intramedic</td>
			<td>7436</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Arterial line guide wire (0.46 mm)			 </td>
			<td>Arrow International</td>
			<td>PW-18080</td>
			<td> Soft tip</td>
		</tr>
		<tr>
			<td>18 G Blunt Needles		</td>
			<td>BD Biosciences</td>
			<td>305180</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Umbilical Tape	</td>
			<td>QC supply</td>
			<td>	140895</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Metzenbaum scissors	</td>
			<td>Cole-Parmer	</td>
			<td>EW-10921-04</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Kelly clamp		</td>
			<td>Cole Parmer</td>
			<td>EW-10918-20</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>3 ml syringe		</td>
			<td>Covidien</td>
			<td>1180300555</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Pathology Dye	</td>
			<td>Bradley Products</td>
			<td>	7365-x</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Digital Camera		</td>
			<td>Panasonic</td>
			<td>Lumix-TZ50</td>
			<td>&nbsp;</td>
		</tr>
	</tbody>
</table>

guide wire assisted catheterization and colored dye injection for vascular mapping of monochorionic twin placentas

Monochorionic (MC) twin pregnancies are associated with significantly higher morbidity and mortality rates than dichorionic twins. Approximately 50% of MC twin pregnancies develop complications arising from the shared placenta and associated vascular connections1. Severe twin-to-twin syndrome (TTTS) is reported to account for approximately 20% of these complications2,3. Inter-twin vascular connections occur in almost all MC placentas and are related to the prognosis and outcome of these high-risk twin pregnancies. The number, size and type of connections have been implicated in the development of TTTS and other MC twin conditions. Three types of inter-twin vascular connections occur: 1) artery to vein connections (AVs) in which a branch artery carrying deoxygenated blood from one twin courses along the fetal surface of the placenta and dives into a placental cotyledon. Blood flows via a deep intraparenchymal capillary network into a draining vein that emerges at the fetal surface of the placenta and brings oxygenated blood toward the other twin. There is unidirectional flow from the twin supplying the afferent artery toward the twin receiving the efferent vein; 2) artery to artery connections (AAs) in which a branch artery from each twin meets directly on the superficial placental surface resulting in a vessel with pulsatile bidirectional flow, and 3) vein to vein connections (VVs) in which a branch vein from each twin meets directly on the superficial placental surface allowing low pressure bidirectional flow. In utero obstetric sonography with targeted Doppler interrogation has been used to identify the presence of AV and AA connections4. Prenatally detected AAs that have been confirmed by postnatal placental injection studies have been shown to be associated with an improved prognosis for both twins5. Furthermore, fetoscopic laser ablation of inter-twin vascular connections on the fetal surface of the shared placenta is now the preferred treatment for early, severe TTTS. 
Postnatal placental injection studies provide a valuable method to confirm the accuracy of prenatal Doppler ultrasound findings and the efficacy of fetal laser therapy6. Using colored dyes separately hand-injected into the arterial and venous circulations of each twin, the technique highlights and delineates AVs, AAs, and VVs. This definitive demonstration of MC placental vascular anatomy may then be correlated with Doppler ultrasound findings and neonatal outcome to enhance our understanding of the pathophysiology of MC twinning and its sequelae. Here we demonstrate our placental injection technique.

Watch this Scientific Journal Video about Guide Wire Assisted Catheterization and Colored Dye Injection for Vascular Mapping of Monochorionic Twin Placentas at JoVE.com

Guide Wire Assisted Catheterization and Colored Dye Injection for Vascular Mapping of Monochorionic Twin Placentas

Vascular mapping of monochorionic (MC) twin placentas after birth provides a means for detailed demonstration of vascular connections between the twins&#x2019; circulations. 
Imbalance of these connections is thought to play a pivotal role in the development of complications of MC twinning including twin-to-twin transfusion syndrome.

Monochorionic (MC) twin pregnancies are associated with significantly higher morbidity and mortality rates than dichorionic twins. Approximately 50% of MC ...

guide-wire-assisted-catheterization-colored-dye-injection-for

Research

JoVE Journal

Medicine

14.8K 次观看.  University of California, San Francisco. 单绒毛膜（MC）后出生的双胞胎的胎盘血管的映射提供了一个双胞胎“环流之间的血管连接的详细示范的手段。这些连接的不平衡被认为是在MC的孪生并发症，包括双对双胞胎输血症候群的发展发挥了举足轻重的作用。