Gall fel, pancreatic juice, duodenal fluid, lymph, or urine infiltrating the retroperitoneal cavity under certain pathological conditions is called retroperitoneal extravasation of fluids.

bubble_chart Etiology

1. The causes of trauma to the posterior wall of the duodenum include sudden deceleration injuries in car accidents and perforation of the posterior duodenal wall or diverticula.

2. The reasons for pancreatic fluid leaking into the retroperitoneal cavity include surgical injury to the pancreas or acute pancreatitis.

3. The causes of bile leaking into the retroperitoneal cavity include surgical or accidental trauma (penetrating or blunt) leading to biliary tract injury; increased biliary pressure due to stone obstruction causing perforation. There are also reports of spontaneous biliary rupture without obvious causes.

4. Lymphatic leakage occurs in diseases involving retroperitoneal lymph nodes and lymphatic vessels or after certain surgeries, such as resection of main artery aneurysms, kidney transplantation, radical hysterectomy, gastric cancer lymph node dissection, and prostate cancer surgery. Retroperitoneal lymphatic effusion often selectively affects the retrorenal space.

5. When the urinary tract ruptures, urine (sometimes mixed with blood) leaks into the retroperitoneal space. The causes of renal pelvis and ureter rupture include penetrating or blunt trauma, surgery, instrumental manipulation, and compression or sprain due to difficult delivery. Kidney parenchymal infection or dilated renal pelvis significantly increases susceptibility to rupture due to external forces. The causes of kidney or renal pelvis rupture include renal tumors, renal subcutaneous nodules, hydronephrosis, stones (pressure necrosis), and increased urinary tract pressure due to lower urinary tract stones or tumors.

This disease usually only presents with grade I or mild pain, differing from the significant pain caused by intra-abdominal infections, and abdominal tenderness and muscle tension are also relatively mild. It often reflexively induces diarrhea or abdominal distension and fullness due to stimulation of the retroperitoneal nerve, and may also lead to intestinal obstruction, mental disorders, systemic exhaustion, or even shock. The severity and urgency of symptoms vary depending on the location, speed, and nature of fluid exudation, as well as the degree of stimulation of the retroperitoneal layer.

When duodenal fluid enters the retroperitoneal cavity due to fistula disease, if the trauma does not cause major penetrating injury, there may be a latent period of several hours before clinical symptoms appear, followed by secondary infection.

If pancreatic fluid leaks into the retroperitoneal cavity, the exudate initially remains within the fascial membrane before spreading to the retrorenal space and generally does not enter the perirenal space. When the exudate is bloody, Turner's sign and Cullen's sign may occur, manifesting as bruising of the skin on both sides of the abdomen and around the umbilicus.

In cases of urinary tract rupture, urine (sometimes mixed with blood) leaks into the retroperitoneal space. If the lesion is in the renal pelvis or ureter, the exudate is primarily urine, whereas if the renal parenchyma is damaged, it is mainly blood. Pyelography shows that as pressure increases, X-ray contrast agents in the renal pelvis may leak into lymphatic vessels, veins, perirenal or periureteral tissues. There have been rare reports of urine leaking into the retroperitoneal cavity without obvious urinary tract pathology. Urinary tract rupture can occur acutely or develop gradually. Some cases have reported spontaneous rupture weeks or months after pyeloplasty. Symptoms caused by urine extravasation vary widely, ranging from very mild to severe, including abdominal pain, the formation of tender masses, abdominal distension and fullness, nausea and vomiting, shivering, fever, exhaustion, or even shock. If the exudate consists solely of urine without bacterial infection and is limited in quantity, it may be absorbed. However, if pathogens are present in the urine, diffuse inflammation of surrounding tissues may occur, leading to suppuration and further formation of perirenal or retroperitoneal abscesses. Some cases have observed the formation and gradual enlargement of retroperitoneal stones due to magnesium ammonium phosphate precipitation. Chronic urinary extravasation can lead to aseptic inflammation and fat dissolution in the perirenal space, forming pseudocysts, often accompanied by palpable masses and varying degrees of abdominal pain. Prolonged urine extravasation may cause fibrosis around the ureter and kidneys, leading to urinary tract stenosis, but true retroperitoneal fibrosis does not occur.

B-mode ultrasound and CT can be used to determine the location and extent of effusion. The density of effusion is generally close to that of water, with some variations depending on its composition. Unless the effusion is surrounded by fascia, its margins are usually less defined compared to abscesses. Typically, the density of effusion alone is insufficient to identify its components, and it can sometimes be difficult to distinguish from abnormal soft tissue masses. Performing fine-needle aspiration under B-mode ultrasound or CT guidance for pathological, bacterial, and generation and transformation studies can be significant for diagnosis.

bubble_chart Treatment Measures

Treatment depends on the cause of the effusion, the rate of exudation, the nature of the fluid, and the amount of exudate. Surgical drainage, closure, and repair of the fistula or diseased area are often required. Some patients also respond well to catheter drainage guided by B-mode ultrasound or CT. Systemic supportive therapy is also important.