Lymphangiography — Pedal & Intranodal — RadCall Procedure Guide

1

Indications & Contraindications

Chylous leak evaluation, lymphatic mapping, pedal vs intranodal approach

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Indications

Chylous leak localization — chylothorax, chylous ascites, chyluria, lymphocele
Pre-procedural planning for thoracic duct embolization — opacify cisterna chyli and thoracic duct to guide access
Lymphatic mapping for lymphedema evaluation
Post-surgical lymphatic injury evaluation (e.g., post-esophagectomy, post-thoracic surgery)
Pleural fluid output ≥500 mL/day with triglycerides ≥110 mg/dL and/or chylomicrons present = chylous effusion

Contraindications

Allergy to Lipiodol (ethiodized oil) or isosulfan blue dye
Right-to-left cardiac shunt (risk of systemic oil embolism)
Severe pulmonary disease (pulmonary oil embolism risk)
Prior lung/mediastinal radiation (increased risk of cerebral oil embolism)
Uncorrectable coagulopathy (for thoracic duct intervention)

Pedal vs. Intranodal Approach

Feature	Pedal Lymphangiography	Intranodal Lymphangiography
Access	Cutdown on dorsal foot lymphatic after blue dye injection	US-guided 25G spinal needle into inguinal lymph node
Technical Difficulty	High — requires microsurgical skill, loupes	Low — straightforward US-guided puncture
Equipment	30G lymphangiography needle, power injector, isosulfan blue	25G spinal needle, connector tubing, 3 mL syringe
Time	2+ hours (including cutdown and infusion)	~50 min shorter on average
Preference	Historical standard	Preferred modern technique

2

Pre-Procedure Planning

Imaging review, chyle confirmation, patient prep, consent

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Imaging & Labs

MR lymphangiography if available (heavily T2-weighted sequences) — map lymphatic anatomy and identify potential leak site before procedure
Review prior CT chest/abdomen/pelvis — assess for adequate-sized inguinal lymph nodes (intranodal approach), cisterna chyli location, effusion/ascites distribution
Confirm chylous nature of effusion: triglycerides ≥110 mg/dL = chylous; presence of chylomicrons is confirmatory
Patients not taking enteral nutrition or on low-fat diet may not meet TG criteria but still may have chyle leak

Patient Preparation

NPO or low-fat diet to reduce chyle flow (improves leak visualization)
Preprocedural US of bilateral inguinal regions to confirm adequate lymph node targets (intranodal approach)
Position supine on fluoroscopy table — wedge under upper back for comfort
Ensure chest tube (if present) is secured and excluded from sterile field
Scout radiographs of abdomen and chest (including obliques) before contrast injection — subtle early opacification can be missed without baseline

Chylous leak confirmed. Pleural/peritoneal fluid analysis: triglycerides ≥110 mg/dL or chylomicrons present.

MR lymphangiography reviewed (if available). T2-weighted sequences for lymphatic mapping.

Inguinal US performed. Adequate-sized lymph nodes identified bilaterally for intranodal access.

Scout radiographs obtained. Baseline abdomen/chest before Lipiodol injection.

Consent obtained. Key risks discussed: fat embolism, allergic reaction, granuloma, pneumonitis (rare). Maximum Lipiodol dose 0.2 mL/kg reviewed.

Allergy screening. No allergy to Lipiodol (ethiodized oil), isosulfan blue dye, or iodinated contrast.

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Relevant Anatomy

Lymphatic system, cisterna chyli, thoracic duct, lymphovenous junction

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Lymphatic System Course

Pedal lymphatics → run along medial dorsum of foot, ascend medial leg and thigh
Inguinal lymph nodes → iliac chain lymph nodes (progression slows through numerous nodes)
Retroperitoneal lymphatics → converge into the cisterna chyli (L1–L2, anterior to vertebral body)
Cisterna chyli → gives rise to the thoracic duct, which ascends through the posterior mediastinum
Thoracic duct → drains into the left subclavian/internal jugular vein junction (lymphovenous junction)

Thoracic Duct Anatomy & Variants

Thoracic duct is the largest lymphatic vessel in the body; drains majority of body lymph
Originates from cisterna chyli at L1–L2, courses rightward then crosses midline at ~T5 to the left
Multiple anatomic variants exist — duplicated ducts, right-sided drainage, or plexiform networks rather than single channel
Right lymphatic duct drains right upper body — separate system, smaller
Injury most common during thoracic surgery near the duct (esophagectomy, spine surgery, mediastinal dissection)

Intranodal Access Anatomy

Inguinal lymph nodes are targeted for intranodal access. On US, the needle tip should be positioned at the junction of the lymph node cortex and medulla to reduce extravasation risk. Positioning the needle in the hilum risks injection into the lymph node vein rather than efferent lymphatics. Through-and-through puncture or puncturing the same node more than once should be avoided, as contrast extravasation reduces efficiency of intralymphatic progression. A bilateral approach is universally used for intranodal technique.

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Technique

Intranodal (preferred) and pedal lymphangiography step-by-step

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Intranodal Lymphangiography (Preferred Technique)

1

Assemble Needle-Syringe System

Remove trocar from a 25G, 3.5-inch spinal needle. Attach 6-inch connector tube (0.2 mL volume) to luer lock hub. Connect to 3 mL polycarbonate syringe filled with Lipiodol. Prime entire system, removing all air. Assemble one system per side before puncture.

2

Sterile Prep & US-Guided Nodal Access

Prep and drape bilateral inguinal regions. Using high-frequency linear US transducer in longitudinal orientation, puncture an inguinal lymph node with the 25G spinal needle at a shallow angle (skin entry ≥2 cm from probe). A controlled "jab" penetrates the node capsule. No local anesthesia needed (25G needle). Position tip at cortex-medulla junction.

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Test & Begin Lipiodol Injection

Test nodal access with gentle hand-injection of Lipiodol under fluoroscopic monitoring. Look for opacification of efferent lymphatics exiting the node. If good intralymphatic flow, access contralateral side with same technique. Inject at ~1 mL per 5 minutes per side.

4

Monitor Progression Under Fluoroscopy

Serial fluoroscopic spot images from hips to abdomen. Shorter intervals (15–30 min) in abdomen where progression may be faster. Typically 3–6 mL oil per side needed to reach retroperitoneum. After retroperitoneal opacification, saline can replace Lipiodol to push the contrast column further (limit total Lipiodol to 0.2 mL/kg).

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Identify Leak & Complete

Continue monitoring until cisterna chyli and thoracic duct opacify. Identify site of chylous leak (Lipiodol extravasation). If performing thoracic duct embolization, proceed to ductal access. Remove needles at completion — no dressings needed for 25G puncture sites.

Pedal Lymphangiography (Traditional Technique)

1

Blue Dye Injection

Inject 1 mL isosulfan blue 1% intradermally with 27G tuberculin syringe into first and third web spaces of foot. Avoid dye leakage which obscures visualization. Prophylactic antibiotics (cefazolin or clindamycin) administered. Wait for blue streaks to appear on dorsum of foot.

2

Pedal Cutdown & Lymphatic Cannulation

Prep and drape foot. Lidocaine wheal over blue streak on first metatarsal dorsum. Careful skin incision (longitudinal preferred). Blunt dissection to identify and skeletonize blue lymphatic vessel. Isolate with 4-0 silk ties proximally and distally. Cannulate with 30G lymphangiography needle (60 cm extension tubing). Secure with additional silk tie.

3

Lipiodol Infusion

Connect to power injector set to mL/hour (NOT mL/second). Infuse at 8–12 mL/h per side. Confirm initial flow with brief fluoroscopy over foot and ankle. Follow contrast column fluoroscopically with serial images from ankle through abdomen. Limit total Lipiodol to 20 mL (or 0.2 mL/kg). Massage medial thigh to facilitate progression.

4

Closure

Remove needle from lymphatic. Remove all silk ties carefully (untie, do not cut through lymphatic). Close with vertical mattress sutures (2-0 polypropylene). Antibiotic ointment, dry sterile gauze, clear film dressing. Suture removal in 7–10 days.

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Key Landmarks

Cisterna chyli, thoracic duct course, lymphovenous junction

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Cisterna Chyli

Located at L1–L2, anterior to vertebral body
Confluence of lumbar lymphatic trunks and intestinal trunk
Target for thoracic duct access during embolization
Opacifies with Lipiodol as a pooling structure in retroperitoneum
Best visualized on 15–20° left posterior oblique fluoroscopy

Thoracic Duct Course

Arises from cisterna chyli, enters thorax through aortic hiatus
Ascends in posterior mediastinum, typically right of midline initially
Crosses midline at approximately T5 level to the left
Courses posterior to aortic arch and left subclavian artery
Multiple variants exist — may be plexiform rather than single channel

Lymphovenous Junction

Thoracic duct drains into junction of left subclavian vein and left internal jugular vein
This is the endpoint of Lipiodol transit — stop injection if oil enters venous system
Right lymphatic duct drains into right venous angle (separate, smaller system)
Leak sites between cisterna chyli and this junction are targets for embolization

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Troubleshooting

Intraoperative problems and solutions

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Poor Lipiodol Progression

Lipiodol Not Ascending Through Lymphatics

Inject additional volume slowly (do not exceed 0.2 mL/kg total). Be patient — progression through pelvis is characteristically slow due to traversal of numerous iliac chain nodes. Massage medial leg and thigh to manually push oil centrally. Consider reverse Trendelenburg positioning. If using pedal approach, ensure needle has not dislodged. After adequate Lipiodol volume, switch to saline to push the contrast column further.

Intranodal Access Failure

Cannot Access Inguinal Lymph Node

Reposition US probe and try a different inguinal lymph node — look for the largest available node. Use shallow-angle approach with skin entry ≥2 cm from transducer for better needle visualization. Small nodes significantly reduce success. If bilateral intranodal access fails, consider switching to pedal lymphangiography.

Perinodal Extravasation

Lipiodol Leaking Around Node Rather Than Into Lymphatics

Avoid through-and-through puncture of the node. Do not puncture the same node more than once. Carefully reposition needle tip within the node cortex (not hilum). If extravasation continues, try a different lymph node. The 25G needle limits injection rate, which reduces extravasation risk.

Pedal Cannulation Failure

Cannot Cannulate Pedal Lymphatic

Ensure adequate blue dye has been taken up (wait longer if needed). Use magnification loupes for better visualization. Try slightly blunting needle tip on sterile towel to prevent double-walling the lymphatic. If lymphatic is transected during dissection, extend incision and attempt a more proximal segment. If pedal approach fails entirely, switch to intranodal technique.

No Leak Identified

Lymphangiogram Does Not Demonstrate Leak Site

Leak may have sealed spontaneously. Consider high-fat meal or enteral feeding challenge to provoke chyle flow and unmask the leak. Obtain delayed imaging at 24 hours (Lipiodol persists in lymphatics) — delayed extravasation may become apparent. Even without visible leak, Lipiodol itself may be therapeutic (sclerosing effect seals leak in ~50% of cases).

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Complications

Fat embolism, allergic reaction, injection site complications

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Major Complications

Fat (oil) embolism — Lipiodol enters pulmonary venous system; limit dose to 0.2 mL/kg (max ~20 mL in adults); stop infusion if Lipiodol enters venous circulation; risk increased with right-to-left shunts or prior lung radiation
Pulmonary oil embolism / pneumonitis — rare with controlled injection and dose limits; presents with dyspnea, hypoxia; supportive care
Cerebral oil embolism — extremely rare; risk with right-to-left cardiac shunt or prior mediastinal radiation
Allergic reaction — to Lipiodol (iodinated oil) or isosulfan blue dye; standard anaphylaxis management

Minor Complications

Granuloma at injection site — foreign body reaction to Lipiodol; usually self-limited
Wound complications (pedal approach) — infection, lymph leak from cutdown site, delayed healing; careful silk tie removal and closure technique
Perinodal extravasation (intranodal) — oil contrast leaking around node; limits effectiveness but generally benign
Blue discoloration of skin/urine — from isosulfan blue dye (pedal approach); transient, resolves spontaneously
Connector hub degradation — oil contrast may degrade plastic tubing; monitor connections for leaks during infusion

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Pearls & Pitfalls

High-yield tips and common mistakes

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Intranodal is MUCH easier than pedal — faster setup, no cutdown, no special needle, less subject to needle dislodgement. Preferred technique in modern practice. Saves ~50 minutes compared to pedal approach.

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Lipiodol is therapeutic in ~50% of chylous leaks. The ethiodized oil has a sclerosing effect on leaking lymphatics, sealing leaks even without subsequent thoracic duct embolization.

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Maximum Lipiodol dose: 0.2 mL/kg (approximately 20 mL total in adults). After reaching this limit, switch to normal saline to push the Lipiodol column further without adding oil volume.

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Fluoroscopic monitoring is essential. Stop injection immediately if Lipiodol enters the venous system (visible at the lymphovenous junction or in pulmonary vasculature).

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Leak identification sets the stage for thoracic duct embolization. The Lipiodol-opacified cisterna chyli serves as the target for percutaneous ductal access, coil embolization, and glue injection.

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Do NOT use mL/second injector settings for pedal lymphangiography. The power injector must be set to mL/hour. A mL/second setting will rupture the cannulated pedal lymphatic.

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Avoid puncturing the same lymph node more than once. Through-and-through or repeat puncture causes extravasation, wastes contrast, and creates lymphovenous communication that allows oil to enter the venous system.

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Aspirate Lipiodol with a large needle (at least 18G). The high viscosity of ethiodized oil requires a large-bore needle to draw it from the glass vial. Use polycarbonate syringes (not standard plastic).

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References & Resources

Primary sources and related procedures

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Key Technique Points

Intranodal technique: position needle at cortex-medulla junction; inject at ~1 mL/5 min per side
Pedal technique: infuse Lipiodol at 8–12 mL/h via power injector set to mL/hour
Total Lipiodol limited to 0.2 mL/kg (~20 mL in adults); substitute saline to propel column further

Primary References

Stecker MS, Fan C-M. Lymphangiography for thoracic duct interventions. Tech Vasc Interventional Rad. 2016;19:277–285. DOI: 10.1053/j.tvir.2016.10.010
Itkin M, Kucharczuk JC, Kwak A, et al. Nonoperative thoracic duct embolization for traumatic thoracic duct leak: experience in 109 patients. J Thorac Cardiovasc Surg. 2010;139(3):584–590.
Nadolski GJ, Itkin M. Feasibility of ultrasound-guided intranodal lymphangiogram for thoracic duct embolization. J Vasc Interv Radiol. 2012;23(5):613–616.
Cope C. Diagnosis and treatment of postoperative chyle leakage via percutaneous transabdominal catheterization of the cisterna chyli: a preliminary study. J Vasc Interv Radiol. 1998;9(5):727–734.