EXPERIMENTAL AND CLINICAL TRANSPLANTATION

Renal transplant provides improved quality of life and survival advantage to patients with end-stage renal disease.¹ Given the shortage of deceased donor kidneys, living donor kidney transplant has increased the donor pool and provides better function as well as a higher rate of graft survival.² The annual rate of living donor renal transplant is steadily increasing, and it is important to reduce harm and ensure the safety of healthy donors.^3,4 Over the past decade, the minimally invasive approach has become the standard of care for living donor nephrectomy (LDN); compared with open nephrectomy, this approach provides a reduction in postoperative complications, a shortened length of hospital stay, and a reduction in postoperative pain.⁵

Post nephrectomy chyle leak is associated with significant morbidity, including protein-calorie malnutrition and prolonged hospital stay. The reported incidence of chyle leak after laparoscopic nephrectomy ranges from 0 to 1.8%.^6,7 Data pertaining to chyle leak after robotic nephrectomy remain scarce with only 1 reported case after robotic LDN.⁸ Here, we report our experience with 2 cases of chyle leak: 1 identified after nephrectomy and 1 identified intraoperatively during robotic LDN. We review the available literature and discuss the diagnostic dilemma and management options for chyle leak after LDN.

Materials and Methods

Electronic databases were searched by 2 separate researchers, including Medline via PubMed and Google Scholar for published studies mapping to Medical Subject Heading (MeSH) terms chyle, chyle leak, chylous ascites, complication, laparoscopic, robotic, and donor nephrectomy. The data from the published articles regarding patient demographics, presentation, and management were compiled and described. We also retrospectively reviewed prospectively maintained electronic records of all robotic LDN performed at our institute from February 2016 to December 2020 to identify patients with chyle leak. This study was approved by our institutional review board (No. HM20018309).

Patient 1
A 52-year-old White woman with no significant past medical history with a body mass index (BMI, calculated as weight in kilograms divided by height in meters squared) of 21 underwent an uneventful robotic left LDN from an emotionally related donor (not a genetic relative). The donor kidney had a single renal artery and vein. No chyle leak was identified intraoperatively. No drain was placed. The patient was discharged to home on postoperative day 2. The patient did well until 4 weeks after surgery when she was readmitted with nausea, decreased oral intake, and abdominal distension. Noncontrast computed tomography (CT) imaging showed a large volume of simple abdominopelvic fluid (Figure 1) for which she underwent therapeutic paracentesis. Fluid studies showed creatinine of 0.8 mg/dL (serum, 0.95 mg/dL), albumin of 2.7 g/dL (serum, 3.0 g/dL), and triglycerides of 894 mg/dL, consistent with chyle leak. Fluid cultures and sensitivities were negative. The patient’s symptoms resolved, and she was discharged on hospital day 4 on a low-fat diet.

She reaccumulated the ascites and required readmission for a repeat paracentesis 1 week later. Total parenteral nutrition (TPN) was initiated, and the patient was maintained on home TPN for a total of 6 weeks. She required 2 more paracenteses that resulted in the resolution of her chyle leak. She was started on a general diet, and an additional ultrasonogram on postoperative day 68 confirmed the lack of appreciable ascites. The patient continued to do well 1 year after donation with a serum creatinine of 1.03 mg/dL.

Patient 2
A 44-year-old Black woman with no significant past medical history with a BMI of 24.5 underwent robotic left LDN from an emotionally related donor (not a genetic relative). The left kidney had a single left renal artery and vein. Intraoperatively, a significant lymphatic leak was identified during the dissection around the left renal artery and vein (Figure 2). Multiple clips were applied over the lymphatic channels to ensure control of any lymph leak. No drain was placed. She was discharged home on postoperative day 3. The patient was prophylactically kept on a low-fat diet for a total of 3 weeks after nephrectomy. Her course was complicated by mild COVID-19 infection at 10 days after kidney donation, from which she recovered uneventfully. The patient had no signs or symptoms of chyle leak 3 months after nephrectomy with excellent preservation of her renal function (serum creatinine, 1.2 mg/dL).

We present 2 cases of chyle leak in living kidney donors that were recognized postoperatively and intraoperatively and managed successfully. Chylous ascites results from the leakage of chyle from damaged lymphatic vessels, particularly the cisterna chyli, during surgery. Chylous ascites is more common after major abdominal surgeries such as esophagectomy and aortic surgery, given the need for extensive lymph node dissection. Only 1 case of chyle leak has been reported after robotic LDN.⁸

Ratner and colleagues reported the first laparoscopic LDN in 1995.⁹ Although laparoscopic LDN remains the gold standard, robotic LDN is gaining popularity. Chyle leak after laparoscopic LDN has variable incidence rates in the literature, ranging from 0 to 1.83%.⁶ Aerts and colleagues performed 1054 minimally invasive LDNs with a chyle leak rate of 0.3%.⁶ In one report, most cases were managed conservatively with diet modifications, whereas ~23% required invasive intervention.¹⁰ There are also a few reported cases of chyle leak after open nephrectomy for donation.¹¹ Given the rarity of the complication and lack of prospective large sample studies that compare the surgical approaches, it is difficult to determine whether robotic nephrectomy is associated with higher rates of leak than laparoscopic or open approaches.

Table 1 summarizes detailed reported cases of chylous leak after minimally invasive (both robotic and laparoscopic) donor nephrectomies in the past 10 years.^6,8,10,12-22 Presentation of chyle leak appears to be bimodal, with early diagnosis in patients with high operative drain output and late recognition in a patient presenting 2 to 3 weeks after nephrectomy. Abdominal pain and distension are the most common presenting symptoms. Seth and colleagues¹⁰ have reported higher prevalence in female patients and that all reports of chyle leak after laparoscopic LDN were after left nephrectomy except for 1 case. This is the expected result, given that more than 80% of donor nephrectomies are on the left side.¹⁰ Given the rarity of the pathology and lack of comparative studies, it is difficult to determine if the surgical approach, hand assistance, or retroperitoneoscopic versus transperitoneal approach affect the rate of chyle leak.

Definitive diagnosis of chyle leak is typically by paracentesis and fluid analysis. Chyle is cloudy white with a triglyceride level 2-fold to 8-fold greater than normal or greater than 110 mg/dL with total protein content ranging from 2.5 to 7.0 g/dL.²³ Computed tomography imaging is not specific for chylous ascites; chyle has the same density as bile, urine, and simple fluid ascites. A classification system was proposed by Ng and He to provide guidance for diagnosis and definitive treatment for chyle leak; that is, drains with leak output less than 300 mL/d indicates mild leak, 300 to 800 mL/d indicates moderate leak, and in excess of 1000 mL/d indicates large leak.²⁰

Management options are aimed at reduction of chyle formation to allow for closure of the injured lymphatic channels. Initial therapy is dietary modification with a low-fat diet with medium-chain triglycerides (MCT). Restriction of long-chain triglycerides avoids their conversion into free fatty acids, which are ultimately transported as chylomicrons into lymphatic vessels. Medium-chain triglycerides are absorbed directly into the portal vein, thus obviating the use of lymphatic vessels. If dietary modification fails to resolve drainage, then the patient may be restricted from oral intake and started on TPN. Octreotide (somatostatin analog) is an option to decrease the uptake of triglycerides and may be used in conjunction with dietary changes.¹⁷ Paracentesis or drainage catheters may provide fluid for diagnosis and symptomatic relief of abdominal distension; however, surgical intervention may be required if conservative management fails.²⁴ Large leaks exceeding >1 L/day or those with reaccumulation of ascites within 2 days of paracentesis are more likely to require invasive intervention. If the patient is a surgical candidate, then laparoscopic exploration and duct ligation may be needed. This procedure requires the identification and ligation of the leaking lymphatic vessels, which can be facilitated by giving the patient a high-fat load (such as butter or oil) preoperatively to increase duct output. If the patient is not an operative candidate or if there is doubt regarding the location of the lymphatic injury, then lymphoscintigraphy or lymphangiogram with glue embolization may be considered.¹⁷

Living kidney donors are typically healthy individuals, altruistically undergoing surgery to benefit someone with end-stage renal disease; thus, it is crucial to minimize any potential complications. We have performed about 200 living donor robotic nephrectomies in our institution, with 1 patient who developed postoperative chyle leak that required intervention; this represents a complication rate of ~0.5%. We routinely use a combination of robotic vessel sealant and bipolar cautery during our dissection, which has been reported by Simforoosh and colleagues in a randomized controlled trial to be safe and effective to prevent lymphocele formation after kidney transplant.²⁵ Chyle leak can potentially be prevented by the use of the aforementioned techniques with liberal clipping of lymphatic structures while dissecting around the abdominal aorta and the renal vasculature. Donors with multiple renal arteries or veins may need excessive dissection, and the energy devices may be unreliable in the presence of extensive lymph nodes or perivascular lymphatic vessels, especially during a left nephrectomy. Variation in the incidence of this rare complication could potentially be related to the dietary habits of the patient population, with higher fatty food intake in the perioperative period being a risk factor for postoperative chyle leak. In our experience, a high index of suspicion for chyle leak is warranted for female donors with low BMI and multiple renal vessels, especially on the left side. In donors that require extensive clipping intraoperatively, we propose a low-fat diet for 2 to 3 weeks after nephrectomy. In high-risk donors, drain placement should be considered, which may facilitate early detection and management and thereby limit the debilitating consequences of delayed diagnosis.

Chyle leak is an uncommon postoperative complication after robotic donor nephrectomy. Management options include paracentesis, diet modification, interventional radiology-guided embolization, and surgical ligation of lymphatic vessels for refractory cases. When identified intraoperatively, chyle leak can be prevented by meticulous ligation and clipping of leaking lymphatic vessels and consideration of postoperative low-fat diet.

Volume: 20 Issue: 10 October 2022

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