PubMed · 16485201
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W Hepp. 2006. [Vascular surgery].. https://doi.org/10.1055/s-2006-921407
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Sudeck's critical point at the rectosigmoid junction is described as the point of origin of the last sigmoid arterial branch, originating from the inferior mesenteric artery (IMA). There is controversy on the importance of Sudeck's point, and the frequency in which the anastomosis is found. Furthermore, the diameter of the anastomosis, if present, may also impact on the viability of the caudal stump. This study aimed to determine the frequency in which a macroscopic anastomosis occurs, between the superior rectal artery and the last sigmoidal branch, in a cadaver population; the diameter of this anastomosis and the distance from the origin of the IMA to Sudeck's point. Sixty-four cadavers were included in the study, excluding those with previous surgery to the rectosigmoid junction. Sudeck's point was carefully identified and dissected to establish the presence of an anastomosis. Subsequent measurements were performed using a digital caliper (accuracy = 0.01 mm). A macroscopic anatomosis was absent in three cases (4.7%). The mean diameter of the anastomosis when present was 1.9 mm (SD: 0.5 mm), and the distance from the origin of the IMA to Sudeck's point was 55.5 mm (SD: 14.6 mm). Although an anastomosis is present in the majority of cases, the vessel is very small in diameter, and may not be sufficient to meet the demands of the caudal stump. The distance from the origin of the IMA to Sudeck's point is sufficient enough to allow for ligation of the IMA proximal to Sudeck's point.
OBJECTIVES: In this study we aimed to quantitate monochorionic twin placental blood flow in vivo through arterio-venous anastomoses (AVA) and corresponding vessels within normal cotyledons. METHODS: The topography of chorionic plate vasculature was mapped using colour Doppler in ten monochorionic diamniotic twin (MCDA) pregnancies. Cotyledonary flow was derived by insonation of chorionic veins draining normal (n=10) and paired control shared cotyledons (n=10). Venous volume flow was calculated from five determinations of vessel diameter and three of time average mean velocity (TAMV). Measurements were repeated every 2-4 weeks from 18 until 32 weeks' gestation. RESULTS: Blood flow through non-shared and shared cotyledons increased with gestation (p<0.0001). Median flow at 28 weeks through shared cotyledons was 16 ml/min (15-21) (median, interquartile range), lower than in shared cotyledons (31, 25-35) (p<0.001), as was median volume flow across gestation calculated as area under the curve (shared cotyledons 126 (122-167), control cotyledons 269 (214-274), p=0.01). However, velocity was similar, with the difference due to smaller vein diameters draining shared compared to normal cotyledons (mean 3.6mm (SD 0.8) vs. 4.5mm (0.8), p=0.004). Ex vivo quantitation of insonated cotyledons and of all cotyledons confirmed the difference in vein diameter in the placentae studied. CONCLUSIONS: Blood flow through shared cotyledons was lower across gestation than through paired normal cotyledons in the placenta studied due to the smaller diameter of the AVA vessels. The size of AVAs rather than simply their presence and direction may contribute to determining transfusional imbalance in monochorionic twins.
Fetoscopic laser coagulation of placental vascular anastomoses is considered to be the treatment of choice in severe twin-to-twin transfusion syndrome. The aim of fetoscopic laser surgery is to separate completely the inter-twin placental circulation. Incomplete laser coagulation may result in residual vascular anastomoses. The incidence and clinical implications of residual anastomoses in twin-to-twin transfusion syndrome treated with fetoscopic laser surgery has not yet been studied. We examined all placentas treated with fetoscopic laser surgery and delivered at our center between June 2002 and December 2005 with vascular injection using colored dyes. Presence of residual anastomoses was studied in association with adverse outcome and inter-twin hemoglobin difference at birth. Adverse outcome was defined as fetal demise, neonatal death or severe cerebral injury. The relation between residual anastomoses and placental localization (anterior or posterior uterine wall) was evaluated. A total of 52 laser-treated placentas were studied. Residual anastomoses were detected in 33% (17/52) of placentas. Adverse outcome was similar in the groups with and without residual anastomoses, 18% (6/34) and 29% (20/70), respectively (p=0.23). Large inter-twin hemoglobin differences (>5g/dL) were found in 65% (11/17) of cases with residual anastomoses and 20% (7/35) of cases without residual anastomoses (p<0.01). Anterior placental localization was not associated with a more frequent presence of residual anastomoses. In conclusion, residual anastomoses at our institution are seen in one-third of monochorionic placentas treated with fetoscopic laser surgery. Although residual anastomoses in our study were not associated with adverse outcome, they were often associated with neonatal hematological complications.