Nephroptosis 

Updated: Jun 25, 2021
Author: Samuel G Deem, DO; Chief Editor: Bradley Fields Schwartz, DO, FACS 

Overview

Practice Essentials

Nephroptosis, also known as a floating kidney and renal ptosis, is a condition in which the kidney descends more than 2 vertebral bodies (or >5 cm) during a position change from supine to upright. The condition is often treated with nephropexy, a surgical procedure that secures the floating kidney to the retroperitoneum.[1]     

History of the Procedure

The mobile kidney was first described in the literature by Franciscus de Pedemontanus in the 13th century. In 1864, Dietl first characterized the symptoms of acute nephroptosis as episodes of acute abdominal pain and vomiting when the patient was upright.[2, 3]  Previously, the condition was often left untreated. Throughout the 1870s, nephrectomy was used as a treatment option, but it was soon abandoned owing to its excessive morbidity. In 1881, Hahn in Berlin described the first nephropexy in which he affixed the ptotic kidney to the retroperitoneum via the perirenal fat using a lumbar incision.[4] In 1882, Bassini began using fascial sutures through the renal capsule to affix the ptotic kidney to the retroperitoneum—a procedure that is still in use today.[3]

The term nephroptosis was first coined by Glenard in 1885. Since then, more than 170 various treatments have been developed for the condition.[5] Following the developments of anesthesia and antisepsis in the late 19th century, enthusiasm for kidney surgery drastically increased; at the end of the 19th century, nephropexy was the most common treatment used by urologists to manage nephroptosis. Many symptoms, including flank pain, lower urinary tract infections, weight loss, gastrointestinal issues, anxiety, palpitations, and even hysteria were attributed to nephroptosis.[5] However, because of the inconsistency of diagnosis and symptoms, nephroptosis fell out of favor as an accepted medical diagnosis.

Because of the high postoperative morbidity rate associated with the procedure and the unreliable symptomatic relief in most patients (likely resulting from the wide variation in diagnostic accuracy), nephropexy also fell out of the normal urological repertoire.[3] A study conducted by Braasch and colleagues in 1948 showed that only 50% of patients who underwent nephropexy to treat nephroptosis achieved symptom resolution. Those authors stressed that conservative therapies, such as wearing a corset or resting frequently in a supine position, should be attempted first and that surgical management should be used only in patients with objective obstruction visualized via intravenous urography. In 1984, McWhinnie and Hamilton declared nephropexy to be an "ineffective treatment for [an] imaginary disease"; misdiagnosis and overuse of the procedure had led to its relegation to the dustbin of abandoned surgical procedures.[5]

However, given modern diagnostic capabilities, it is currently recognized that surgical repair is beneficial in certain symptomatic patients with obstruction of the collecting system or renal blood flow caused by documented kidney ptosis.[6] In 1993, Urban and colleagues at Washington University successfully conducted the first laparoscopic nephropexy.[7] Subsequently, McDougall and colleagues (2000) further legitimized laparoscopic nephropexy as a valid surgical treatment for nephroptosis by showing improvement in pain conditions in a long-term outcome study.[8]

Problem

Nephroptosis, also known as floating kidney and renal ptosis, is a condition in which the kidney descends more than 2 vertebral bodies (or >5 cm) during a position change from supine to upright. In the upright position, this translocation can lead to symptoms of vomiting and acute abdominal pain due to acute obstruction or ischemia of the kidney.

Epidemiology

Frequency

Nephroptosis is a fairly rare condition, and the number of radiological diagnoses exceeds the number of patients with symptoms attributable to the condition. Many studies have estimated that nearly 20% of women have nephroptosis on routine intravenous urography, but far fewer (10%-20%) actually present with symptoms attributable to the condition.[9]

Symptomatic nephroptosis is more common in younger adult women (age 20-40), with a female-to-male ratio of 5-10:1.[10] In addition, the condition is more common on the right side (70% of cases).

Of interest, nearly 64% of patients with fibromuscular dysplasia of the renal artery also have ipsilateral nephroptosis.[3]

Etiology

The cause of nephroptosis is relatively unknown, but there are similarities among most symptomatic patients.  Most cases of nephroptosis are in thin white women, and it is theorized that a lack of perirenal fat and fascial support in those patients can lead to the downward translocation of the kidney. In addition, many patients with nephroptosis have a longer-than-normal renal vascular pedicle, which allows for displacement of the kidney in the sagittal and frontal axes.[1]  Rarely, nephroptosis may occur in a kidney transplant recipient.[11]  

The current theory attributes the pain in symptomatic nephroptosis to one or more of the following[3] :

  • Acute hydronephrosis caused by kinking of the proximal ureter following the sudden descent of the kidney
  • Transient kidney ischemia, when elongation of the renal vessels results in narrowing of their lumen
  • Visceral nerve stimulation due to traction on the renal hilum

Presentation

The typical clinical presentation of symptomatic nephroptosis involves a young (aged 20-40 y) thin woman with costovertebral, flank, or lower-quadrant abdominal pain that occurs in the upright position and is relieved by lying down and exacerbated by long periods of standing or physical activity.[6, 1] Many patients with the condition may also seek care upon palpating a lower-abdominal mass while in the upright position.[3]

Risk factors for developing symptomatic nephroptosis include extreme weight loss or frequent extreme physical activity.

The most severe manifestation of symptomatic nephroptosis is Dietl crisis, which is characterized by severe colicky flank pain, nausea, vomiting, chills, tachycardia, oliguria, and transient hematuria or proteinuria due to obstruction.[5] The pain can be relieved by upward movement of the kidney back to the renal fossa in the supine position and with the head down and feet elevated or in the knee-chest position.[3]

Pertinent questions in the medical history include the following:[1]

  • Is pain exacerbated by standing up from a supine position?
  • Does severe physical activity exacerbate the pain?
  • Is the pain alleviated by lying in a supine position?
  • Have you had significant weight loss in your lifetime?
  • Have you recently had hematuria, recurrent urinary tract infections, kidney stones, or hypertension?
  • Can you feel any masses in your lower abdomen on the same side as your pain?

Upon physical examination, at times, the ptotic kidney can be palpated in the ipsilateral lower abdomen when the patient assumes an upright position. The anterior abdominal wall may also show some minor indenting.[1]

Kidney ptosis and kidney ectopia can be included on the same differential, as both are inferior displacements of greater than 2 vertebral bodies from L2 (right kidney) and 1 cm higher than L2 (left kidney). However, ectopia is a permanent congenital displacement of the kidney to this position, and patients with this condition have shorter ureters and an ectopic renal arterial blood supply. Ptotic kidneys have normal-length ureters and renal arteries with a normal origin from the abdominal aorta, whereas an ectopic kidney has a shorter ureter, given its fixed inferior position.[12, 13]

Other differential diagnoses include the following:[1]

  • Renal colic with associated urolithiasis
  • Cholecystitis (right side)
  • Intermittent bowel obstruction
  • Spastic bowel disease
  • Hematuria
  • Pyelonephritis
  • Ovarian vein syndrome
  • "Nutcracker" syndrome (compression of the left renal vein between the superior mesenteric artery and the abdominal aorta)
  • Ovarian cystic disease and possible ruptured ovarian cyst

Indications

Nephropexy is indicated in a very small percentage of nephroptosis cases. It is reserved for symptomatic patients with flank pain (often > year in duration) in whom studies confirm kidney descent upon transition from a supine to an erect position and in whom intravenous urography, ultrasonography, or nuclear scintigraphy shows delayed excretion and hydronephrosis.[14]

Relevant Anatomy

The kidneys are paired, bean-shaped retroperitoneal organs that sit below the level of the diaphragm. The right kidney is positioned posterior to the liver, and the left is positioned posterior to the spleen. The right renal pelvis traditionally sits at the level of L2, with the left renal pelvis sitting about 1 cm higher, but its normal position can vary from vertebral bodies T12 and L3 (±2 vertebral bodies in both the superior and inferior directions). The kidneys are usually 9-13 cm in length, and the upper portions can be protected by the 11th and 12th ribs. Normally, the posterior side of the kidney contacts the diaphragm superiorly and the vertebral column muscles (psoas major and quadratus lumborum) inferiorly.

The renal parenchyma consists of the renal medulla and cortex, which is surrounded by a fibrous renal capsule. Superficial to the renal capsule that surrounds the kidney is a layer of perirenal fat, and surrounding the perirenal fat is the membranous connective-tissue layer known as the renal (Gerota) fascia. Outside of the renal fascia is the pararenal fat, which is covered by parietal peritoneum anteriorly and transversalis fascia posteriorly.

The kidneys contain a medial fissure called the renal hilum, through which renal vessels, nerves, and the renal pelvis pass. The renal calyces drain into minor infundibula and then into a major infundibulum or directly into a major infundibulum, which then drains into the renal pelvis. The renal pelvis tapers into the ureteropelvic junction inferiorly. The ureter then descends retroperitoneally (on the anterior surface of the psoas major), passing posteriorly to the testicular/ovarian vessels, anteriorly to the bifurcation of the common iliac artery, and distally into the pelvic region.

Ureteral sympathetic afferent nerves travel with the lesser, least, lumbar, and splanchnic nerves. That is why visceral ureteral pain refers to dermatomes T10 to L2.

The renal arteries arise from the abdominal aorta at the level of vertebral body L4, inferior to the origin of the superior mesenteric artery, and superior to the origin of the inferior mesenteric artery. They transverse across the crus of the diaphragm and enter the renal hilum; on the right side, the artery usually travels behind the inferior vena cava before entering the kidney.

The renal veins emerge from anterior and posterior sides of the renal pelvis and anastomose at the renal hilum before draining into the inferior vena cava. The left renal vein courses posterior to the pancreas and anterior to the abdominal aorta. The shorter right renal vein courses behind the descending duodenum and the head of the pancreas.[15]

Contraindications

Nephropexy is contraindicated in asymptomatic nephroptosis.

 

Workup

Laboratory Studies

Results of relevant laboratory studies in patients with nephroptosis are as follows:

  • Urinalysis may reveal microhematuria; however, the workup for microhematuria should be completed in a standard fashion before nephroptosis is implicated as its cause.
  • Urine culture results are typically negative.
  • Blood urea nitrogen (BUN), creatinine, and electrolyte levels are typically normal.
  • Blood lactate dehydrogenase levels may be acutely elevated, supporting the hypothesis of transient kidney ischemia. [16, 1]

Imaging Studies

Intravenous urography is the primary diagnostic tool in nephroptosis. In patients with nephroptosis, intravenous urography shows kidney descent of two or more vertebral bodies (ie, > 5 cm) when the patient moves from the supine to the upright position (see the images below). Delayed imaging may also show hydronephrosis.[1, 3]

Intravenous urogram. (A) Supine intravenous urogra Intravenous urogram. (A) Supine intravenous urogram showing the kidney in proper position with the renal pelvis opposite vertebral body L3 and no hydronephrosis. (B) Upright intravenous urogram showing descent of the kidney and malrotation, with subsequent hydronephrosis development. (Reprinted from Hoenig DM, Hemal AK, Shalhav AL, Clayman RV. Nephroptosis: a "disparaged" condition revisited. Urology. Oct 1999;54(4):590-6, with permission from Elsevier.)

In patients with nephroptosis, diuretic (furosemide) renography may show hydronephrosis and/or decreased split kidney function when scans taken in the supine position are compared with those taken in the sitting position.[1, 17]

Retrograde pyelography can demonstrate obstructive changes in the ureter, pelvis, or calyces (eg, kinking) when the kidney position is changed by tilting the operative table.[3]

Computed tomography scan findings are usually normal when the patient is in the supine position.[1]

Supine-to-upright ultrasonography and Doppler ultrasonography scans can show kidney ptosis, while the Doppler study can show diminished blood flow in the ptotic kidney when the patients is upright. This method may yield sensitivity superior to that of isotope renography (renal scanning) in detecting symptomatic nephroptosis.[18]

When scanning is performed in both a supine and sitting position, it may show decreased blood flow and reduced clearance.[19]

Grauer et al reported use of an anterograde urodynamic study, the modified Whitaker test, to diagnose nephroptosis after standard imaging was inconclusive.[10]   

 

Treatment

Medical Therapy

Nephroptosis should be treated only in the rare patients who present with a full array of symptoms and confirmation of the diagnosis with one of the imaging studies described above (see Imaging Studies).

Owing to hypochondriac behaviors that often accompany symptomatic nephroptosis, nonsurgical treatments are recommended as a first-line intervention. Some such treatments include weight gain, therapy with gastrointestinal medications, abdominal wall–strengthening exercises, abdominal wall binders (eg, corsets), and frequent rests in the supine position. Extracorporeal support of the ptotic kidney appears to be the most effective nonsurgical treatment, and abdominal binders and corsets were in common use throughout the 1900s.[3] Similar to a truss for treating a hernia, these approaches are all temporizing maneuvers.

Surgical Therapy

All surgical therapies for nephroptosis are based on the principle that the ptotic kidney must be irreversibly fixed into its normal position by securing the kidney or perinephric tissue (renal capsule, perirenal fat, Gerota fascia) to the body wall high in the retroperitoneum via either suture or subsequent adhesion formation. A few of the prominent surgical procedures are discussed below.

Nephropexy

This procedure is used to affix the kidney to the retroperitoneal tissues via open or laparoscopic surgery. The renal capsule is attached to the psoas or quadratus lumborum muscle with nonabsorbable sutures, fascial or muscle bands, and/or polyglactin mesh.[1] This procedure was pioneered by Bassini and is currently the most commonly used open surgical nephropexy technique. Using the 12th rib as a sling or skewer has generally fallen out of favor.

Endourological procedures

In the last 20 years, the endourological procedures laparoscopic nephropexy and circle (U) nephrostomy tube insertion have gained favor as surgical treatments for nephroptosis.[3]

Laparoscopic nephropexy

This is a laparoscopic procedure that closely duplicates the open nephropexy described above but that results in significantly lower morbidity. Laparoscopic nephropexy confers a significant and durable improvement in quality of life in approximately 70%-90% of patients who undergo the procedure.[20, 8, 21, 22] The technique is practiced at many centers with extensive laparoscopic experience.

In 1997, Fornara and colleagues compared open with laparoscopic nephropexy. The mean operative time was 49 minutes and 61 minutes, respectively. Postoperative analgesic control was measured to be an average of 15 mg morphine equivalents in the laparoscopic group and 38 mg in the open group. In the laparoscopic group, the average hospital stay was 3.7 days, versus 16 days in the open surgery group. In addition, split renal function improved from 38% to 47% postoperatively in the laparoscopic group.[20]

Multiple laparoscopic procedural techniques exist, including the use of absorbable mesh, fixation staples, and/or sutures placed through Gerota fascia and sutures through the renal capsule. Many studies have shown that tissue adhesives (eg, butyl cyanoacrylate) and medical devices (eg, tension-free vaginal tape) can also be used to secure the kidney high in the retroperitoneum.[23, 24, 25]  Successful kidney fixation has been reported with the sliding cup technique utilizing suture and nonabsorbable polymer clips.[26]

Multiple long-term outcome studies have proven the efficacy of laparoscopic nephropexy.[8, 9, 21, 27] These reports, with follow-up times ranging from 3.3-8.2 years, showed that, postprocedure, 71% of patients reported an improvement in quality of life and showed an 80%-91% reduction in pain.

The original laparoscopic procedure, known as the Washington University technique (transperitoneal laparoscopic retroperitoneal nephropexy), is described in detail in Intraoperative Details.

Circle (U) nephrostomy tube insertion

Note the image below.

Circle (U) nephrostomy tube treatment. The nephros Circle (U) nephrostomy tube treatment. The nephrostomy tube enters above the 12th rib, passes through the kidney through an upper pole, and exits through a middle calyx and below the 12th rib, suspending the kidney. (Reprinted from Hoenig DM, Hemal AK, Shalhav AL, Clayman RV. Nephroptosis: a "disparaged" condition revisited. Urology. Oct 1999;54(4):590-6, with permission from Elsevier.)

In this procedure, first described by Szekely and colleagues in 1997, a 14F-16F nephrostomy tube is placed through two points in the middle and upper calices, with the tube entering above the 12th rib and exiting below the 12th rib, forming a sling used to suspend the kidney to the 12th rib. The tube is then sutured to the skin with moderate tension and left in place for 2-3 weeks to allow sufficient scar formation for kidney fixation.[28]

In a long-term outcome study of 90 patients over 12 years, Szekely and colleagues were able to show a 79% long-term success rate with nephrostomy tube insertion based on pain intensity. They reported a mean operative time of 18 minutes and an average hospital stay of 3 days for the procedure. This method, although lacking in widespread application, is considered a low-morbidity, easy-to-perform, cost- and time-effective alternative to laparoscopic nephropexy by those adept in its use.[29] However, because this technique is not widespread in application, corroborating data from other institutions as to its success are absent.

Preoperative Details

Preoperative consultation includes the following:

  • Thorough medical history
  • Verification of symptoms (in the awake patient via imaging studies in both supine and upright positions) [21]
  • Perioperative antibiotics
  • Possible preoperative mechanical bowel preparation of low-sediment diet and glycerin enema for bowel decompression to facilitate laparoscopy

Intraoperative Details

Transperitoneal laparoscopic retroperitoneal nephropexy

Transperitoneal laparoscopic nephropexy. The later Transperitoneal laparoscopic nephropexy. The lateral border of the renal capsule has been sutured to quadratus lumborum fascia. In addition, the superior flap of the hepatic triangular ligament has been sutured to the anterior renal capsule. (Reprinted from Elashry OM, Nakada SY, McDougall EM, Clayman RV. Laparoscopic nephropexy: Washington University experience. J Urol. Nov 1995;154(5):1655-9, with permission from Elsevier.)

This procedure was first successfully conducted by Urban and colleagues in 1993 at Washington University in St. Louis, Missouri.[30]

A transperitoneal approach is preferred over a retroperitoneal approach because it allows for horizontal and vertical fixation of the kidney while eliminating the need for conversion from retroperitoneal to transperitoneal approach in the rare situation when the kidney is both ptotic and markedly displaced anteriorly.[16] However, more recent studies have shown success and symptom resolution in retroperitoneal approach laparoscopic nephropexy using nonabsorbable sutures placed horizontally rather than in the classic vertical distribution.[31]

Retroperitoneal laparoscopic nephropexy may be particularly indicated in patients who have undergone prior abdominal surgery.[6] Furthermore, tissue adhesives such as butyl cyanoacrylate have shown initial success in affixing the kidney to the retroperitoneum.[24, 23] In 2002, Gyftopoulos et al showed that, with a mean follow-up of 25 months, 9 patients who had undergone adhesive nephropexy had significant improvement on pain scales, as well as proper kidney fixation on follow-up radiographic studies.[32] Nonetheless, further long-term outcome studies are still needed.

The procedure described below has been used in multiple long-term outcome series of laparoscopic nephropexy and has proven to be a safe treatment associated with low morbidity that resolves symptoms due to nephroptosis.[8, 9, 21]

The patient is placed in the lateral decubitus position. A Veress needle is passed into the peritoneum, and the abdomen is subsequently insufflated to 25 mm Hg. A 12-mm umbilical port is placed, followed by insertion of a 30° 10-mm laparoscope. Three additional ports are also placed, as follows:

  • A 12-mm port subcostally at the midclavicular line (Note that a 5-mm port can be substituted, if preferred; in this case, all sutures are then passed via the 12-mm umbilical port.)
  • A 5-mm port in the anterior axillary line at the level of the umbilicus
  • A 5-mm port subcostally in the anterior axillary line

An incision is made at the line of Toldt. The right colon is mobilized and the retroperitoneum exposed. The Gerota fascia is incised, and the kidney is dissected and mobilized on the anterior, posterior, superior, inferior and lateral aspects using electrosurgical scissors and a hook electrode. The medial portion of the kidney can be left undisturbed. The posterior wall of the retroperitoneum is bluntly dissected to expose fascia overlying the psoas major and quadratus lumborum muscles.

The patient is then repositioned in a steep head-down position, allowing for cephalad displacement of the kidney. The kidney is affixed using simple or horizontal mattress sutures of 1-0, nonabsorbable, intracorporeal sutures along the lateral border of the renal capsule from the upper to lower pole of the kidney. The sutures are then placed through the fascia of the quadratus lumborum. Intracorporeal knot tying or Lapra-Ty clips can be used for suture fixation. In addition, newer technologies such as polyglactin mesh, fibrin glue, or nonabsorbable polymer clips can be used to secure the kidney in place high in the retroperitoneum or to add to the security of other types of repairs.[21, 33] A horizontal line of fixation can also be created by anastomosing the superior aspect of the incised posterior coronary hepatic ligament to the anterior renal capsule with nonabsorbable sutures.

Finally, check for hemostasis at the 5-mm port.

Postoperative Details

Patients usually resume oral intake the night of surgery and begin ambulating on the first or second postoperative day, with discharge on the second or third day. Usually, patients receive oral analgesics for pain control and return for follow-up imaging studies 2-6 months following the procedure.[16]

Complications

Potential complications of nephroptosis include the following[1] :

  • Pyelonephritis
  • Renal calculi
  • Hematuria
  • Hypertension
  • Kidney ischemia
  • Flank pain

Potential complications of nephropexy include the following[20] :

  • Urinary tract infection
  • Uncorrected ptotic kidney
  • Retroperitoneal hematoma
  • Bowel injury or puncture during trocar placement
  • Conversion to open nephropexy
  • Muscle paresthesia
  • Genitofemoral nerve injury or entrapment

Outcome and Prognosis

Laparoscopic nephropexy and circle U nephrostomy tube treatment for nephroptosis yield excellent results, with effective pain control in properly selected patients.[19, 34] Multiple long-term outcome studies have shown that patients undergoing laparoscopic nephropexy have significantly reduced morbidity, decreased postoperative discomfort, and a faster recovery time than patients undergoing open nephropexy.

A study by Hubner and colleagues (1994) showed that laparoscopic nephropexy had a mean operative time of 2.7 hours, with 10 mg of morphine required for adequate pain control following the procedure. Follow-up showed anecdotal resolution of symptoms and no significant kidney descent upon repeat intravenous pyelography.[35] However, the follow-up period in this study was only 10.5 months.

In 2000, McDougall and colleagues showed that, with an average follow-up of 3.3 years, analogue pain scales improved by 80%, with 21% of patients considered cured and 71% of patients improved. The procedure failed in only 7% (one patient). Radiographic studies showed that ptosis resolved in all patients, and renal function was unchanged as evaluated by serum creatinine levels.[8]

In 2001, Plas and colleagues published a study validating laparoscopic nephropexy with data garnered from patients with an average of 5.9 years of follow-up.[9] Patient follow-up included standing and supine intravenous pyelography to confirm permanent fixation of the kidney. Ptosis recurred in 20% of patients, while all patients reported anecdotal improvement in symptoms.

Most recently, Gozen and colleagues have shown laparoscopic nephropexy to be a suitable, established, and safe treatment for nephroptosis, with an improvement of symptoms, increased patient satisfaction, and 71% of patients reporting an improvement in quality of life over an average follow-up of 8.2 years. Pain relief was on an anecdotal basis only; 85% of patients were pain-free postprocedure.[21]

Future and Controversies

The existence of pathological nephroptosis and the necessity of its surgical treatment have been debated by urologists for more than a century. However, current knowledge suggests that, in the rare symptomatic patient, laparoscopic nephropexy can prove to be a safe and effective treatment for symptomatic nephroptosis as documented by appropriate radiographic studies.

Many other possible therapies could improve on transperitoneal or retroperitoneal laparoscopic nephropexy, such as the following:

  • Using tissue adhesives (these require further study)
  • Percutaneous suture suspension placement [36]
  • Novel surgical tools such as tension-free vaginal tape [25] and nonabsorbable polymer clips [33] for kidney fixation