Venous Anatomy and Collateral Pathways of the Pelvis: An Angiographic Review

Potential causes of iatrogenic intraoperative bleeding during C1 surgeries: a CT 3D rendering study

BACKGROUND

Iatrogenic intraoperative bleeding during C1 surgeries is difficult to manage.

PURPOSE

To investigate the potential causes of iatrogenic intraoperative bleeding in atlas surgeries.

STUDY DESIGN

This was a retrospective study, observational cohort of patients with DICOM.

PATIENT SAMPLE

High-resolution head and neck computed tomography angiography (CTA) images from 551 subjects were included.

OUTCOME MEASURES

Ponticulus posticus (POPO), vertebral artery (VA), venous plexus communication.

METHODS

Three dimension rendering was utilized in the present study. Potential arterial bleeding was evaluated based on the variation in the VA and the polymorphism of the POPO over the groove for VA (GVA). The communication of the venous plexus in the occipitoatlantal region was investigated to assess the venous hemorrhage.

RESULTS

Among the 551 atlases examined, POPOs were identified on 155 sides, resulting in a prevalence of 14.07% (155/1102). These POPOs (n=155) were reclassified into four types: tiny spur (54.84%), long spur (7.10%), ossified bridge (30.32%), and ossified canal (7.74%). In 42.92% (473/1102) of cases, the VA did not directly contact the sulci of the GVA, creating space for the passage of the rich venous plexus that drained intracranial venous blood outflow to various extracranial layers. Moreover, in 12.7% of the subjects, the study revealed the presence of additional foramens in the posterior lamina of C1, which served as a conduit for the communicating vein CONCLUSION: The potential underestimation of polymorphism in POPOs and VAs can lead to arterial bleeding, whereas a lack of understanding of the intricate condylar emissary venous plexus can result in venous hemorrhage. To mitigate iatrogenic hemorrhage during C1 surgeries, a preoperative HEAD AND NECK CTA is recommended, and heightened caution should be exercised during dissection in the lateral half of the C1 lamina. Furthermore, unknown causes of intraoperative bleeding may arise during the posterior C1 approach; modifications should be considered based on the specific circumstances encountered.

Anatomical, Pathophysiological, and Clinical Aspects of Extra-Pelvic Varicose Veins of Pelvic Origin

Venous hypertension in the pelvic veins can result in the development of varicosities in the perineum, and sometimes also in the lower extremities. These varicose veins are anatomically and functionally different from typical varicosities associated with an incompetence of the saphenous veins. Since the pelvic cavity is anatomically separated from the lower extremity and perineum by muscles and skeleton, there are only a few routes through which pelvic veins can communicate with extra-pelvic veins. These routes should primarily be examined during diagnostic workout. In this review article, clinical anatomy concerning varicose veins of pelvic origin is presented, and the anatomically-driven diagnostics for these atypical varicose veins are discussed. Focus on ultrasonographic detection of the escape points, which are located at the sites where the incompetent intra-pelvic and extra-pelvic veins are connected-such as the perineal veins, veins running alongside the round ligament of the uterus, the obturator vein, as well as the inferior and superior gluteal veins-is emphasized.