Deep Inferior Epigastric Perforator Flap: Abdominal Flap Dissection

Procedure: This video depicts the abdominal flap dissection for a delayed bilateral deep inferior epigastric perforator (DIEP) flap reconstruction in a 53-year-old female patient status post bilateral mastectomy for breast cancer. Introduction: The DIEP flap is an autologous form of breast reconstruction following mastectomy, which can allow single-stage reconstruction in contrast to tissue expander reconstruction. The procedure is often performed in a two-team approach with simultaneously dissection of the abdominal flaps and internal mammary vessel harvest / recipient site preparation. Indications/Contraindications: DIEP flap breast reconstruction is recommended in patients who wish to achieve breast reconstruction with autologous tissue and have suitable abdominal donor tissue. It is also considered a preferred method of reconstruction for patients who have undergone radiation. Absolute contraindications include previous abdominoplasty and high-risk medical comorbidities, with elevated BMI, smoking and advanced age considered relative contraindications. Materials and Methods: Upper followed by lower abdominal incisions were made while sparing the umbilicus on a healthy stalk after ensuring the abdomen would be able to close. After dissection of the superficial inferior epigastric vein, medial and lateral row perforators were identified and appropriate perforators were then selected and dissected. The course of the appropriate perforator(s) into the deep inferior epigastric artery and vein was dissected to their take-off from the external iliac system. Results: The abdominal flap was prepared with identification of the major perforator vessel(s). Once the deep inferior epigastric vessels were clipped, they were ready for microvascular anastomosis. The fascial defects were next closed, followed by abdominal closure and neo-umbilical inset. Conclusion: This report demonstrates how to perform the critical steps of abdominal flap dissection for the DIEP flap.

Purpose of technique: According to the American Cancer Society, 1 in 8 American women will develop breast cancer in their lifetime. 1 Following mastectomy, many women will consider breast reconstruction. Since the introduction of the Women’s Health and Cancer Rights Act, published trends show an increase in post mastectomy breast reconstruction among US women from 12% in 1998 to 36% in 2011. 2 The Deep Inferior Epigastric Perforator (DIEP) flap has now become the most common autologous approach to breast reconstruction. It provides a large volume of soft, malleable tissue that resembles the natural consistency of the breast and may allow patients to achieve breast augmentation in one procedure, as compared to tissue expander reconstruction. It is the flap of choice for autologous breast reconstruction because it combines a long pedicle with a relatively straightforward dissection, minimal donor site morbidity, and improves the donor site contour. Proper patient/case selection (indications): Patients considering breast reconstruction post mastectomy have choices of implant-based and autologous methods. Autologous reconstruction is typically favored in patients who have undergone mastectomy flap radiation. However, patient choice is key in the decision making process after thorough surgeon-patient discussion.  In an evaluation of patient motives when considering implant versus autologous reconstruction, women seeking implant-based reconstruction are more focused on surgical aspects including recovery time and surgical scars, while those considering autologous DIEP flap are more concerned with regaining a breast most resembling their prior breast consistency.3 A study of over 300 women who underwent breast reconstruction concluded that women who underwent autologous breast reconstruction were more likely to be younger (10 -49 years old) and overweight with no significant differences based on race, ethnicity, education or income. 4 Patient selection for DIEP flap also favors patients with minimized comorbidities who can withstand a more lengthy surgery. Contraindications (absolute and relative): Absolute contraindications to DIEP flap breast reconstruction include prior procedures that would compromise abdominal flap integrity including abdominoplasty and large transverse or oblique incisions. Prior abdominal liposuction is not an absolute contraindication, but a preoperative computed tomography should be performed to identify usable perforators. Free flap surgeries typically require a prolonged anesthesia time, therefore patients should generally be in good health and/or medically cleared for surgery by their primary care provider.  Age is not a contraindication to surgery, though patients under the age of 80 are preferred. 5 BMI >35 kg/m2 is a relative contraindication. Aspirin and herbal medications, which can inhibit platelet function and clotting, should be discontinued 3 weeks prior to surgery. 5 Active smoking is associated with an increased risk of multiple complications, including fat necrosis and abdominal wound dehiscence.  If possible, smokers should refrain from smoking for 3 months prior to surgery. In the senior author’s practice, all patients who are smokers are nicotine tested prior to surgery. Advantages and disadvantages over alternative techniques: In a study of patients who underwent postmastectomy breast reconstruction, DIEP flaps were found to have the greatest overall satisfaction when compared to tissue expanders / implants, latissimus dorsi pedicled flaps and transverse rectus abdominus muscle (TRAM) flaps.6 While implant-based and autologous reconstructions were found to have similar aesthetic outcomes short-term, autologous reconstruction was deemed more aesthetically favorable in long term outcomes (>8 years postoperatively). 7 The cost of a DIEP flap is initially higher than implant-based reconstruction, however, this cost diminishes over time with multiple clinic visits for tissue expander fills and subsequent surgery for implant exchange. Disadvantages of the DIEP flap procedure compared to implant-based reconstruction include longer operative time and initial recovery period, additional donor site morbidity and risk of flap necrosis requiring additional surgery. These disadvantages are particularly notable in high risk patients: elderly (>60 years old), advanced disease (AJCC 7th edition stage III or IV), any comorbidities (Charlson score / Deyo Modification) or use of pre- or post-mastectomy radiotherapy with a larger growth in implantation-based reconstruction in recent years. 8 Furthermore, nonirradiated chests were associated with better breast sensation post implant reconstruction, while irradiated breasts were found to have better sensation levels post DIEP flap reconstruction.9 This may change with newer resensitization techniques. Complications and risks:  DIEP flap complications include venous congestion, marginal necrosis, and partial / total flap loss. Donor site complications include delayed wound healing, abdominal hernias and abdominal wall bulging. 10

Instrumentation: Standard surgical instruments were utilized including both monopolar and bipolar electrocautery. An intraoperative Doppler was utilized for perforator identification. In addition, free tissue transfer required standard microsurgical instruments, including microsurgical scissors, forceps, and needle holders. A venous coupler was used for venous anastomosis. Depending on surgeon preference, there are various techniques that may be used for intraoperative assessment of flap perfusion, ranging in cost, from clinical assessment of capillary refill/Doppler assessment, thermal imaging, to indocyanine green angiography. Postoperative monitoring techniques also largely vary based on surgeon preference. In the senior author’s practice, clinical assessment is typically sufficient, though implanted Doppler probes and flap pulse oximetry (Vioptix) may be used at higher cost. Setup: The patient was marked preoperatively in standing position. After induction of anesthesia, the major perforators were identified on CTA imaging and marked on the abdomen. The surgical team was divided in two: (1) Abdominal Dissection and (2) Chest Dissection, working simultaneously to prepare the flap and recipient vessels. Preoperative workup: Preoperative workup included a reconstructive consultation focused on patient oncologic history and treatment plan (including but not limited to tumor biology, staging, chemotherapy, radiation), comorbidities, and desired outcomes. Physical exam evaluated mastectomy flaps, since delayed, as well as donor sites for scarring and appropriate volume. Review of patient’s prior imaging (mammography, ultrasound, MRI) may prove useful to understand prior tumor location. Further imaging such as CTA or MRA can be utilized to guide assessment of perforator location and viability.11 Patient may need initial “babysitter” tissue expander placement prior to DIEP flap reconstruction to preserve the mastectomy pocket. Anatomy and landmarks with figures as needed: Figure 1: DIEP Flap Reconstruction Illustration 12 Figure 2: Anatomy of Deep Inferior Epigastric Artery Exiting Above the Inguinal Ligament 13 Figure 3: Deep Inferior Epigastric Artery as a Trans Muscular Perforator 14 The DIEP flap has become the mainstay of autologous breast reconstruction. It allows replacing breast tissue with abdominal tissue while sparing rectus muscle and fascia (Figure 1, 0:05). 12 The deep inferior epigastric artery arises from the external iliac immediately above the inguinal ligament (Figure 2, 0:14). 13 It ascends along the medial margin of the abdominal inguinal ring, piercing the transversalis fascia, running between the rectus abdominis and its posterior sheath until it anastomoses above the umbilicus with the superior epigastric branches of the internal thoracic artery and the lower intercostal arteries. The DIEP is considered a muscle sparing perforator flap (Figure 3, 0:20) 14 which means that the vessels pass source to skin through and between deep tissues, including the rectus abdominus muscle. The DIEA usually gives 2 rows of perforators, medial and lateral, though there can be variability. Lateral perforators are often dominant and easier to dissect because they run more perpendicularly through the fascia. The medial perforators provide better perfusion to the flap as a whole but have a longer intramuscular course requiring more extensive dissection. 90% of the major perforators for the DIEP flap are located within a 6cm radius lateral and inferior to the umbilicus. 15 Detailed steps to procedure: The patient was marked in a standing position. The flaps were outlined, and perforators identified both by measuring their distance from the umbilicus on the CT, and with doppler.  The umbilicus was incised circumferentially around a healthy stalk. The upper abdominal incision was made, and closure was approximated prior to beginning the lower abdominal incision. The lower abdominal incision was made carefully not to injure the superficial inferior epigastric vein which was dissected at this time. The flap was raised from lateral to medial in a suprafascial plane. It could proceed rapidly using monopolar cautery until the lateral edge of the rectus abdominus muscle. Next the perforators were dissected, isolated, and appropriate perforator(s) were selected after applying clamps to the remaining perforator(s). Once the dominant perforator was identified, it was carefully dissected through the anterior rectus sheath and followed along its pedicle course using bipolar cautery. The pedicle can take a combination of subfascial, intramuscular and/or submuscular course until its take of near the external iliac vessels is confirmed. Once isolated, the deep inferior epigastric artery and vein were clipped and cut and oriented with a marking pen to avoid twisting of the pedicle.

The optimal DIEP flap abdominal dissection consists of negligible rectus muscle sacrifice during pedicle dissection. The perforator(s) chosen should be able to perfuse a large skin island. During abdominal closure, the incision should ideally be positioned low to conceal the scar, however, should not come at the expense of perforator sacrifice. One must be cautious to choose the appropriate perforators to ensure appropriate perfusion of the flap. Furthermore, it is typically not preferred to include a perforator near the take off of the deep inferior epigastric vessels to avoid shortening the pedicle length. With respect to the abdominal flap, the procedure should be performed similar to an abdominoplasty with central undermining to allow tension free closure and avoid devascularization of the flap. Furthermore, minimal rectus dissection could help decrease the chance of abdominal wall hernia or bulging.

Critical steps of the procedure: The critical step of this portion of the procedure is the proper identification and dissection of perforator vessels. This is facilitated through preoperative imaging (CTA), intraoperative Doppler and intra-operative perforator isolation and clamping to select the most dominant perforator(s). Selection of the appropriate perforator(s) is crucial to provide adequate perfusion of the flap as well as avoid shortening of the pedicle. Common modifications:  Some centers do not routinely CTA image the perforators preoperatively. Otherwise, flap harvest commonly follows a similar methodology, although, some select centers may perform robotic pedicle harvest to minimal fascial incision with pedicles that have a short intramuscular course. Although not visualized in the video, nerve dissection often accompanies vessel dissection. In conjunction with intercostal nerve via conduit, this may allow for slow increase of breast sensation over time. Common pitfalls: Common pitfalls include inability to dissect both hemi-abdominal flaps simultaneously due to need for midline retraction during flap harvest. Furthermore, placing the final scar as low as a typical abdominoplasty incision is often difficult. Less commonly, damage to the perforators during flap harvest could potential render the flap unusable. Troubleshooting of the technique(s): When encountering difficulties during perforator dissection, referral to a preoperative CT scan, as well as intraoperative Doppler probe assessment, are vital in identifying the course of the pedicle through the rectus muscle. Limitations of the technique: At times, multiple perforators are required to perfuse the entire flap and give the desired volume of reconstruction. This occasionally requires dividing the rectus muscle between multiple perforators which increases the risk of abdominal hernia or bulge. A technique has been described for intra-flap anastomosis which spares this division of the rectus by dividing and then re-anastomosing these perforators around the muscle during flap dissection. 16 This technique however does require an additional anastomosis and does increase operative time. Potential further applications of the technique(s): The techniques utilized in this procedure can be applied to any free flap. Knowledge of how to perform this procedure is very useful to any reconstructive or aesthetic surgeon as post-mastectomy autologous breast reconstruction continues to grow.

There was no funding for this project and the authors have no financial disclosures or conflicts of interest.

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