Anatomical Variations of Iliac Vein Tributaries and Their Clinical Implications During Complex Pelvic Surgeries

Delineation of the internal iliac vein using MRI with true FISP sequence in patients with locally recurrent rectal cancer: A pilot study using CT/MRI fusion

PURPOSE

This study assessed the feasibility of using three-dimensional (3D) models of intrapelvic vascular patterns constructed using computed tomography (CT) and magnetic resonance imaging (MRI) fusion data for preoperative planning in patients with locally recurrent rectal cancer.

METHODS

Eleven patients scheduled for pelvic exenteration were included. The 3D fusion data of the intrapelvic vessels constructed using CT and MRI with true fast imaging with steady-state precession sequence (True FISP) were evaluated preoperatively. Contrast ratios (CR) between the piriformis muscle and the intrapelvic vessels were calculated to identify a valid modality for 3D modeling and creating CT/MRI fusion-reconstructed volume-rendered images.

RESULTS

The CR values of the internal and external iliac arteries were significantly higher on CT images than MR images (CT vs. MRI; 0.63 vs. 0.45, p < 0.01). However, the CR value of the internal iliac vein was significantly higher on MR than CT images (CT vs. MRI; 0.23 vs. 0.55, p < 0.01).

CONCLUSIONS

MRI with True FISP yielded high signal-to-noise ratios and aided in delineating the internal iliac vein around the piriformis muscle. More precise 3D models can be constructed using this technique in the future to aid in the resection of locally recurrent rectal cancer.

An updated classification of the anatomical variations of the internal iliac venous drainage system: Surgical implications for anterior lumbar spinal approaches

BACKGROUND

Advanced pelvic surgery is associated with potential vascular risks. The aim of this study was to complete the existing classification of the anatomical variations of the internal iliac veins encountered on a series of preoperative angio CT with a view to performing anterior lumbar spine surgery.

MATERIALS AND METHODS

In this monocentric retrospective study conducted between 2010 and 2020, all preoperative angio CT performed before an anterior lumbar surgery were systematically analyzed. All the abnormalities of the iliac veins were referenced in an updated classification system.

RESULTS

910 patients (431 men and 479 women) with a mean age of 49 years [16-88] were included. Apart from the most common variant in the population (type I), 64 anatomical variations (7.0%) in the iliac veins were reported and classified according to our new classification. The percentage of coverage of the L4-L5 intervertebral disc is 52%, including 32% by the inferior vena cava before the confluence of the common iliac veins. At the level of the L5-S1 intervertebral disc, the coverage is 30% (same distribution between left and right).

CONCLUSIONS

Variations of the iliac veins are frequent, and contrary to what one might think, and even if they can represent an anatomical trap during surgery, certain variations do not limit anterior lumbar spine surgery and are not more associated with vascular complications. Nevertheless, these anatomical variations must be known before any advanced pelvic surgery. Depending on their distribution, level L5-S1 is more suitable for ALIF, level L4-L5 for OLIF approaches.

Beyond Total Mesorectal Excision: Compartment-based Anatomy of the Pelvis Revisited for Exenterative Pelvic Surgery

OBJECTIVE

Magnetic resonance imaging-based subdivision of the pelvis into 7 compartments has been proposed for pelvic exenteration. The aim of the present anatomical study was to describe the topographic anatomy of these compartments and define relevant landmarks and surgical dissection planes.

BACKGROUND

Pelvic anatomy as it relates to exenterative surgery is complex. Demonstration of the topographic peculiarities of the pelvis based on the operative situs is hindered by the inaccessibility of the small pelvis and the tumor bulk itself.

MATERIALS AND METHODS

Thirteen formalin-fixed pelvic specimens were meticulously dissected according to predefined pelvic compartments. Pelvic exenteration was simulated and illustrated in a stepwise manner. Different access routes were used for optimal demonstration of the regions of interest.

RESULTS

All the 7 compartments (peritoneal reflection, anterior above peritoneal reflection, anterior below peritoneal reflection, central, posterior, lateral, inferior) were investigated systematically. The topography of the pelvic fasciae and ligaments; vessels and nerves of the bladder, prostate, uterus, and vagina; the internal iliac artery and vein; the course of the ureter, somatic (obturator nerve, sacral plexus), and autonomic pelvic nerves (inferior hypogastric plexus); pelvic sidewall and floor, ischioanal fossa; and relevant structures for sacrectomy were demonstrated.

CONCLUSIONS

A systematic approach to pelvic anatomy according to the 7 magnetic resonance imaging-defined compartments clearly revealed crucial anatomical landmarks and key structures facilitating pelvic exenterative surgery. Compartment-based pelvic anatomy proved to be a sound concept for beyond TME surgery and provides a basis for tailored resection procedures.

Three-Dimensional in Vivo Anatomical Study of Female Iliac Vein Variations

OBJECTIVE

To investigate female iliac vein variations by using the computed tomography angiography (CTA) three-dimensional (3 D) reconstruction technique.

METHODS

We retrospectively studied 1623 patients undergoing abdominal and pelvic CTA scanning for gynecological diseases from December 2009 to December 2018. Accurate digital 3 D models of the iliac vein were constructed using Mimics 19.0 software and used to study the morphology and variations. Variations in the common iliac vein (CIV), external iliac vein (EIV) and internal iliac vein (IIV) were classified as type I, abnormal number of veins; type II, abnormal communicating branches; or type III, other variations.

RESULTS

The overall variation rates of the iliac vein and CIV were 51.57% (837/1623) and 20.33% (330/1623), respectively. The main type of CIV variation was type II. The main type I CIV variation was the absence of the CIV (98.15%), which mostly occurred on the right side (64.81%, 35/54). Type II CIV variation was the most common, with abnormal communicating branches between the left CIV and right IIV (81.78%, 211/258). The overall variation rates of the EIV and IIV were 36.66% (595/1623) and 49.60% (805/1623), respectively, mainly on the right side. The main type of variation was type I. Among them, the division of the IIV into two branches plus convergence with the ipsilateral EIV was the most common (22.98%, 373/1623).

CONCLUSION

In this study, approximately half of the patients had iliac vein variations. The preoperative identification of iliac vein variation may reduce vascular injury in pelvic surgery.

Towards Standardisation of Technique for En Bloc Sacrectomy for Locally Advanced and Recurrent Rectal Cancer

Treatment strategies for advanced or recurrent rectal cancer have evolved such that the ultimate surgical goal to achieve a cure is complete pathological clearance. To achieve this where the sacrum is involved, en bloc sacrectomy is the current standard of care. Sacral resection is technically challenging and has been described; however, the technique has yet to be streamlined across units. This comprehensive review aims to outline the surgical approach to en bloc sacrectomy for locally advanced or recurrent rectal cancer, with standardisation of the operative steps of the procedure and to discuss options that enhance the technique.

A prospective randomized feasibility trial comparing angiography and angiography with intravascular ultrasound for treatment of hemodialysis access failures

OBJECTIVE

Hemodialysis accesses suffer from limited primary patency requiring frequent interventions, revisions, or even abandonment. Prolongation of access life and usability with minimization of these adverse events is paramount. Endovascular methods are established first-line interventions for failing arteriovenous access and treatment of venous outflow stenoses. The Primary goal of this feasibility study was to evaluate intravascular ultrasound (IVUS) during interventional treatments on outcomes in those undergoing angiography for failing hemodialysis access. Secondary goals were to determine differences between IVUS and angiography on vessel and lesion characteristics and impact on treatment.

METHODS

In this prospective, randomized controlled trial, patients scheduled for angiography to evaluate and treat a failing hemodialysis access were randomized to use of angiography (DSA) alone or angiography plus IVUS (DSA + IVUS). Patients were treated by a standardized protocol and seen in follow-up at 2 weeks, and every 3 months for 2 years or until a study endpoint was reached. Measurement of vessel diameters, % stenosis, lesion length, and study endpoints (AV access thrombosis, re-intervention, or surgical revision) were recorded.

RESULTS

A total of 55 subjects were enrolled, 27 in the DSA cohort and 28 in the DSA + IVUS cohort. There were 41 treated lesions in each group. Freedom from the composite endpoint of AV access thrombosis or re-intervention was 46.3% in the DSA cohort and 61.0% in the DSA + IVUS cohort (p = 0.27). Diameter measurements matched between the two imaging modalities only 9 times out of 41 total comparison measures. In pre-treatment lesions with >80% stenosis, IVUS had a greater tendency than DSA to underestimate the severity of stenosis, whereas in pre-treatment lesions with 50-80% stenosis, DSA was more likely than IVUS to underestimate the severity of stenosis. Post-treatment % stenosis had mean difference of -7.5% between DSA versus DSA + IVUS cohorts. In five lesions with <30% stenosis measured by angiogram, IVUS led to treatment escalation.

CONCLUSION

In the interventional treatment of failing angioaccess, IVUS and angiography differ in the vast majority of cases in measurement of vessel diameter. A significant number of patients were found to have suboptimal therapeutic response by IVUS only, which led to an escalation in treatment, and in over one-third of cases, the IVUS results led to a change in treatment plan. The improved patency rates in the IVUS group was not statistically significant in this small population but should be further investigated in a larger trial.

Variant formation of left common iliac vein by the confluence of four veins

Common iliac vein variations are relatively rare compared to the variations of external and internal iliac veins. A rare pattern of formation of common iliac vein by the confluence of four veins is being reported here. The left common iliac vein was formed by the union of left external iliac vein, internal iliac vein, iliolumbar vein and a common trunk formed by the obturator and vesical veins. External iliac vein and obturator veins were connected by a communicating vein. Both external and common iliac veins were respectively medial to the external and common iliac arteries. Knowledge of this variant formation of common iliac vein could be useful to radiologists, gynecologists and orthopedic surgeons.

Pelvic Lymphadenectomy in Gynecologic Oncology-Significance of Anatomical Variations

Pelvic lymphadenectomy is a common surgical procedure in gynecologic oncology. Pelvic lymph node dissection is performed for all types of gynecological malignancies to evaluate the extent of a disease and facilitate further treatment planning. Most studies examine the lymphatic spread, the prognostic, and therapeutic significance of the lymph nodes. However, there are very few studies describing the possible surgical approaches and the anatomical variations. Moreover, a correlation between anatomical variations and lymphadenectomy in the pelvic region has never been discussed in medical literature. The present article aims to expand the limited knowledge of the anatomical variations in the pelvis. Anatomical variations of the ureters, pelvic vessels, and nerves and their significance to pelvic lymphadenectomy are summarized, explained, and illustrated. Surgeons should be familiar with pelvic anatomy and its variations to safely perform a pelvic lymphadenectomy. Learning the proper lymphadenectomy technique relating to anatomical landmarks and variations may decrease morbidity and mortality. Furthermore, accurate description and analysis of the majority of pelvic anatomical variations may impact not only gynecological surgery, but also spinal surgery, urology, and orthopedics.

Surgical anatomy of the pelvis for total pelvic exenteration with distal sacrectomy: a cadaveric study

PURPOSE

Intraoperative bleeding from the pelvic venous structures is one of the most serious complications of total pelvic exenteration with distal sacrectomy. The purpose of this study was to investigate the topographic anatomy of these veins and the potential source of the bleeding in cadaver dissections.

METHODS

We dissected seven cadavers, focusing on the veins in the surgical resection line for total pelvic exenteration with distal sacrectomy.

RESULTS

The presacral venous plexus and the dorsal vein complex are thin-walled, plexiform, and situated on the line of resection. The internal iliac vein receives blood from the pelvic viscera and the perineal and the gluteal regions and then crosses the line of resection as a high-flow venous system. It has abundant communications with the presacral venous plexus and the dorsal vein complex.

CONCLUSION

The anatomical features of the presacral venous plexus, the dorsal vein complex, and the internal iliac vein make them highly potential sources of bleeding. Surgical management strategies must consider the anatomy and hemodynamics of these veins carefully to perform this procedure safely.

Unique Case of Recurrent Pelvic Congestion Syndrome Treated with Median Sacral Vein Embolization

BACKGROUND

Pelvic congestion syndrome (PCS) is defined as noncyclical pelvic pain or discomfort caused by dilated parauterine, paraovarian, and vaginal veins. PCS is typically characterized by ovarian venous incompetence that may be due to pelvic venous valvular insufficiency, hormonal factors, or mechanical venous obstruction.

METHODS

We describe a case of a 38-year-old multiparous female with a history of pelvic pressure, vulvar varices, and dyspareunia. She underwent left gonadal vein coil embolization in 2014 for PCS that lead to symptomatic relief of her pain. Four years later, the patient returned for recurrent symptoms. Magnetic resonance venogram demonstrated dilated pelvic varices. The previously embolized left gonadal vein remained thrombosed, and there was no evidence of right gonadal vein insufficiency. However, catheter-based venography revealed a large, dilated, and incompetent median sacral vein.

RESULTS

Pelvic venography demonstrated left gonadal vein embolization without any evidence of reflux. The right gonadal vein was also nondilated without reflux. Internal iliac venography showed large cross-pelvic collaterals and retrograde flow via a large, dilated median sacral vein. Coil embolization of the median sacral vein resulted in a dramatic reduction of pelvic venous reflux and resolution of symptoms.

CONCLUSIONS

Recurrence of PCS can occur after ovarian vein embolization through other tributaries in the venous network. The median sacral vein is a rare cause of PCS. We present an interesting case of a successfully treated recurrent PCS with coil embolization of an incompetent median sacral vein.