Lymphatic-Sparing Medial Thighplasty Using Preoperative Methylene Blue Mapping

Alfio Luca Costa; Gloria Fanton; Franco Bassetto; Vincenzo Vindigni

doi:10.20944/preprints202607.1162.v1

Submitted:

14 July 2026

Posted:

16 July 2026

You are already at the latest version

Abstract

Medial thighplasty after massive weight loss carries high rates of wound dehiscence, seroma and prolonged edema, and there is evidence that thigh lift can alter lower limb lymphatic drainage. Conventional refinements such as liposuction assistance, limited undermining and fascial anchoring still rely on the surgeon’s implicit understanding of distorted lymphatic anatomy in post bariatric tissues. Direct intraoperative visualization of lymphatic pathways is not part of routine practice. We describe a simple adjunct based on preoperative intradermal methylene blue injection to map superficial lymphatic collectors before medial thigh lift. After standard markings in the standing position, a dilute methylene blue solution is injected intradermally along the planned medial thigh resection pattern once anesthesia is induced and before skin preparation. At flap elevation, lymphatic collectors appear as fine blue channels within the dermis and immediate subdermis, running parallel to the great saphenous axis and defining a practical limit for safe depth of dissection. The surgeon maintains dissection superficial to the stained collectors and avoids transfixing them with suspension sutures or deep liposuction passes. The technique is particularly useful in massive weight loss patients with thin, inelastic skin and deep folds in whom depth perception is unreliable, and for less experienced surgeons who are still developing three dimensional familiarity with the medial thigh. Methylene blue is inexpensive and easily integrated into the operative workflow without specialized equipment or relevant time cost. This lymphatic sparing mapping strategy merits prospective evaluation regarding its effect on seroma, lymphocele and postoperative edema after medial thighplasty.

Keywords:

medial thighplasty

;

methylene blue injection

;

lymphatic collectors

;

massive weight loss

;

lymphatic sparing mapping

Subject:

Medicine and Pharmacology - Surgery

Preoperative Methylene Blue Mapping Technique

Adult massive weight loss patients undergoing vertical or combined medial thighplasty for symptomatic medial thigh redundancy are candidates for mapping. We favor its use in marked laxity, previous groin or thigh surgery or preexisting limb edema. Patients with dye hypersensitivity, known glucose 6 phosphate dehydrogenase deficiency or pregnancy are excluded.

Markings are made in the standing position, outlining a vertical excision along the medial thigh from groin to medial knee and, when needed, a horizontal limb in the inguinal crease. The skin island is drawn so that methylene blue can be injected only within tissue that will be excised.

After induction of general anesthesia and before antiseptic preparation, 1 percent methylene blue is diluted with normal saline to an approximate concentration of 0.25 percent and loaded into 1 mL syringes with 27 gauge needles. Small intradermal blebs of 0.1 to 0.2 mL are injected along the medial markings inside the resection pattern, beginning near the medial knee and progressing proximally toward the groin, with blebs spaced 3 to 4 cm apart. In combined patterns, additional microinjections are placed along the horizontal limb, again confined to the future skin island. Each injection produces a narrow intradermal wheal with visible blue discoloration and minimal subdermal spread (Figure 1).

After injection the thigh is not manipulated. Standard antiseptic preparation and draping provide an interval of roughly 7 to 10 minutes for the dye to migrate along superficial collectors. Before incision the surgeon verifies that all stained skin lies within the intended resection and incorporates any stained area outside the markings into the excision.

Thighplasty then proceeds according to the planned pattern. If liposuction is performed, tumescent solution is infiltrated and aspiration is maintained in a superficial plane above Scarpa fascia. At incision, the dermo adipose flap is elevated with scissors or electrocautery. Superficial lymphatic collectors draining the limb appear as fine blue lines within the deep dermis and immediate subdermal fat and define the safe depth of dissection (Figure 2).

When dissection approaches the blue level the surgeon maintains a superficial plane; if a stained vessel must be crossed, this is done at a single point with bipolar coagulation or fine ligature.

Fascial suspension sutures to Colles fascia or other deep anchors are placed under direct vision, avoiding transfixion of blue lymphatics. At closure methylene blue staining remains limited to deep dermal and subdermal tissue and does not interfere with assessment of flap perfusion. Patients are informed preoperatively about the off label use of methylene blue and the possibility of transient blue urine or stool.

Discussion

Medial thighplasty after massive weight loss remains a high risk contouring procedure. Large series report overall complication rates of 42.7 to 68 percent, with seroma in 8 to 25 percent of thighs and frequent prolonged edema [1,2]. Persistent limb swelling is described in a subset of patients, suggesting a lymphatic component to morbidity [1,2].

Objective data support that surgery in this region can alter lymphatic drainage. Hachul Moreno et al. used lymphoscintigraphy after crural lifting and found postoperative abnormalities in approximately one third of limbs [3]. Gentileschi and colleagues, studying post bariatric brachioplasty with a medial incision and limited undermining, found no significant impairment of upper limb lymphatic drainage when dissection remained superficial [4]. Together, these studies underline the need to preserve superficial lymphatic collectors during contouring procedures.

Current strategies to reduce fluid collections rely on liposuction assisted techniques, restricted undermining, wedge patterns and careful tension distribution [1,5,6]. These refinements do not provide real time visualization of lymphatic pathways. In post bariatric tissues, with thin inelastic skin, deep folds and prior scars, depth judgment based only on anatomy and experience is unreliable and may result in inadvertent transection of key collectors or deep placement of suspension sutures.

Preoperative intradermal methylene blue mapping addresses this limitation by making superficial lymphatic collectors visible in the operative field. The principle is borrowed from sentinel lymph node biopsy in breast and melanoma surgery, where vital dyes trace lymphatic channels in real time [7,8]. In our adaptation the dye is injected strictly within the skin island scheduled for excision. The blue channels then act as a visual reference for safe depth during flap elevation, liposuction and placement of fascial suspension sutures and provide immediate feedback to surgeons in training.

The safety of this adjunct depends on how methylene blue is used. Reports from breast surgery describe skin and fat necrosis, infection, prolonged inflammation, tattooing and rare anaphylaxis after periareolar or parenchymal injections, particularly when concentrated dye is deposited subdermally in skin that is not excised [9,10,11,12]. By confining small volume, dilute intradermal injections to the planned skin island, our technique minimizes the risk of dye related necrosis or permanent staining in preserved skin and ensures that any localized reaction is removed with the specimen. Injection outside the resection area, use of larger boluses or deeper subdermal placement would expose residual skin to these complications and should be avoided.

Alternative intraoperative lymphatic imaging modalities such as indocyanine green lymphography allow dynamic mapping but require near infrared cameras and consumables that are not widely available [13]. Methylene blue is inexpensive, widely supplied and familiar to anesthesiologists and surgeons. Its off label use for lymphatic mapping in this setting should be discussed with patients and restricted to centers able to manage infrequent hypersensitivity reactions and familiar with the pharmacology of the dye. Screening for known glucose 6 phosphate dehydrogenase deficiency is prudent because of the theoretical risk of hemolysis.

This Ideas and Innovations article does not provide quantitative outcome data. The proposed technique is a simple adjunct that can be integrated into medial thighplasty algorithms based on limited undermining and fascial anchoring, and a simple trick to avoid lymphatic damage during thighplasty, very useful for young doctors. Prospective studies should evaluate its effect on seroma, drain duration, early and late edema, lymphocele and patient reported limb heaviness. Pending such data, the low cost and plausible pathophysiologic rationale of preoperative methylene blue lymphatic mapping support its use as a lymphatic sparing strategy in selected medial thighplasty patients after massive weight loss.

Author Contibutions

Conceptualization, A.L.C., F.B. and V.V.; methodology, A.L.C., F.B. and V.V.; investigation, A.L.C. and G.F.; resources, F.B. and V.V.; writing, original draft preparation, A.L.C.; writing, review and editing, G.F., F.B. and V.V.; visualization, A.L.C. and G.F.; supervision, F.B. and V.V.; project administration, A.L.C. A.L.C. served as first author and corresponding author and takes responsibility for the overall integrity, technical accuracy and scientific content of the manuscript. Formal analysis was not applicable, as the manuscript is a technical report describing a surgical technique. All authors have read and agreed to the published version of the manuscript.

Ethical approval

This article is a Technical Note describing a variant of an established surgical technique, namely preoperative intradermal methylene blue mapping of the superficial lymphatic collectors during medial thighplasty. The manuscript describes the technique itself. It does not report patient outcome data, it involved no prospective enrollment of subjects, no allocation of patients to a study protocol, and no systematic collection of data for the purpose of generating generalizable knowledge. For this reason, the work does not meet the definition of a clinical trial or of an interventional or observational clinical study under the applicable Italian and European legislation: Italian Legislative Decree no. 211 of 24 June 2003 (implementing Directive 2001/20/EC) defines “clinical trial” (sperimentazione clinica) as a study on human beings intended to discover or verify the clinical or pharmacological effects of investigational medicinal products, and expressly does not apply to non-interventional or observational studies. Regulation (EU) no. 536/2014, Article 2, defines a clinical trial by reference to the prospective assignment of subjects to a therapeutic strategy decided in advance and outside normal clinical practice. In the present case, methylene blue was used within normal clinical practice as an accepted mapping dye, and no procedure additional to routine care was applied for study purposes. Under the definition of “research” shared by the Declaration of Helsinki (which governs medical research involving human subjects, i.e., systematic investigation intended to develop generalizable knowledge) and by 45 CFR 46.102 of the US Common Rule (research as “a systematic investigation designed to develop or contribute to generalizable knowledge”), this technical description does not reach the threshold for mandatory Ethics Committee review. This position is consistent with COPE guidance, which recognizes that the reporting of cases arising during normal clinical practice, for educational purposes and without a systematic research design, may fall outside the definition of research requiring ethics committee approval. Accordingly, no formal approval number or written exemption was issued by the competent Ethics Committee, the Comitato Etico Territoriale Area Centro-Est Veneto (formerly Comitato Etico per la Sperimentazione Clinica della Provincia di Padova), based at the Azienda Ospedale-Università di Padova, whose remit covers clinical trials on medicinal products and medical devices, pharmacological observational studies, and compassionate use programs. A purely technical description of this kind does not fall within these categories.

Informed consent

For this type of study informed consent is not required.

Financial Disclosure Statement

All authors certify that they have no financial relationships or activities that could be perceived to influence the work reported in this manuscript. No external funding, grants, material support, medical writing assistance, or article processing charges were received. No consultancies, equity interests, royalties, patent interests, paid advisory roles, board memberships, or employment relationships are reported by any author. These disclosures align with each author’s 36-month COI questionnaire.

Conflicts of Interest statement

The authors declare that they have no conflicts of interest to disclose.

Funding

This research received no external funding.

Data Availability Statement

The original contributions presented in this study are included in the article/supplementary material. Further inquiries can be directed to the corresponding author(s).

References

Gusenoff, J.A.; Coon, D.; Nayar, H.; Kling, R.E.; Rubin, J.P. Medial thigh lift in the massive weight loss population: outcomes and complications. Plast. Reconstr. Surg. 2015, 135(1), 98–106. [Google Scholar] [CrossRef] [PubMed]
Sisti, A.; Cuomo, R.; Zerini, I.; et al. Complications Associated With Medial Thigh Lift: A Comprehensive Literature Review. J. Cutan. Aesthet. Surg. 2015, 8(4), 191–197. [Google Scholar] [CrossRef] [PubMed]
Moreno, C.H.; Neto, H.J.; Junior, A.H.; Malheiros, C.A. Thighplasty after bariatric surgery: evaluation of lymphatic drainage in lower extremities. Obes. Surg. 2008, 18(9), 1160–1164. [Google Scholar] [CrossRef] [PubMed]
Gentileschi, S.; Servillo, M.; Ferrandina, G.; Salgarello, M. Lymphatic and Sensory Function of the Upper Limb After Brachioplasty in Post-Bariatric Massive Weight Loss Patients. Aesthet. Surg. J. 2017, 37(9), 1022–1031. [Google Scholar] [CrossRef] [PubMed]
Shermak, M.A.; Mallalieu, J.; Chang, D. Does thighplasty for upper thigh laxity after massive weight loss require a vertical incision? Aesthet. Surg. J. 2009, 29(6), 513–522. [Google Scholar] [CrossRef] [PubMed]
Xie, S.M.; Small, K.; Stark, R.; Constantine, R.S.; Farkas, J.P.; Kenkel, J.M. Personal Evolution in Thighplasty Techniques for Patients Following Massive Weight Loss. Aesthet. Surg. J. 2017, 37(10), 1124–1135. [Google Scholar] [CrossRef] [PubMed]
Simmons, R.M.; Smith, S.M.; Osborne, M.P. Methylene blue dye as an alternative to isosulfan blue dye for sentinel lymph node localization. Breast J. 2001, 7(3), 181–183. [Google Scholar] [CrossRef] [PubMed]
Tanis, P.J.; Nieweg, O.E.; Valdés Olmos, R.A.; Kroon, B.B. Anatomy and physiology of lymphatic drainage of the breast from the perspective of sentinel node biopsy. J. Am. Coll. Surg. 2001, 192(3), 399–409. [Google Scholar] [CrossRef] [PubMed]
Reyes, F.; Noelck, M.; Valentino, C.; Grasso-Lebeau, L.; Lang, J. Complications of methylene blue dye in breast surgery: case reports and review of the literature. J. Cancer Published. 2010, 2, 20–25. [Google Scholar] [PubMed]
Bleicher, R.J.; Kloth, D.D.; Robinson, D.; Axelrod, P. Inflammatory cutaneous adverse effects of methylene blue dye injection for lymphatic mapping/sentinel lymphadenectomy. J. Surg. Oncol. 2009, 99(6), 356–360. [Google Scholar] [CrossRef] [PubMed]
Lee, J.H.; Chang, C.H.; Park, C.H.; Kim, J.K. Methylene blue dye-induced skin necrosis in immediate breast reconstruction: evaluation and management. Arch. Plast. Surg. 2014, 41(3), 258–263. [Google Scholar] [CrossRef] [PubMed]
Jangjoo, A.; Forghani, M.N.; Mehrabibahar, M.; Sadeghi, R. Anaphylaxis reaction of a breast cancer patient to methylene blue during breast surgery with sentinel node mapping. Acta Oncol. 2010, 49(6), 877–878. [Google Scholar] [CrossRef] [PubMed]
Yamamoto, T.; Yamamoto, N.; Doi, K.; et al. Indocyanine green-enhanced lymphography for upper extremity lymphedema: a novel severity staging system using dermal backflow patterns. Plast. Reconstr. Surg. 2011, 128(4), 941–947. [Google Scholar] [CrossRef] [PubMed]

Figure 1. Schematic representation of recommended injection pattern and dissection plane for medial thighplasty with methylene blue mapping.

Figure 2. Intraoperative view of medial thigh flap elevation showing fine blue stained lymphatic collectors within the dermis and subdermal fat that define the safe depth of dissection.

Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

© 2026 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Copyright: This open access article is published under a Creative Commons CC BY 4.0 license, which permit the free download, distribution, and reuse, provided that the author and preprint are cited in any reuse.