NEWBORN SURGERY - 1976

2. SPECIAL SECTIONS

8. Malformations of Individual Organs and Systems

Cystic Kidney Diseases

During the neonatal period, two MAIN TYPES OF cystic lesions are predominantly identified: multicystic dysplastic kidney and Polycystic Kidney Disease.

The multicystic kidney is enlarged, formed by numerous thin-walled cavities containing clear or turbid fluid, and features an uneven, lobulated surface. It is typically accompanied by ureteral involvement, manifesting as hypoplasia or aplasia of its terminal segments or maldevelopment of the ureteropelvic junction. The condition is unilateral, though congenital Anomalies of the contralateral kidney or Ureter may coexist (M. D. Javad-Zade, 1961, et al.). In Johnston's series (1966) of 19 infants with unilateral multicystic kidney, 8 were found to have Hydronephrosis and ureterohydronephrosis, and 3 had megaureter of the contralateral organ.

Multicystic kidney disease is a rare condition. According to statistics by Schröder et al. (1970), only 192 cases have been described in world literature. The most extensive experience in treating this anomaly in newborns and infants in their first months of life belongs to Pathak and Williams (1964), who analyzed 60 cases.

The origins of multicystic and polycystic kidney diseases are attributed to impaired renal development during Embryogenesis (Fig. 103).

Class="center">Fig. 103. Stages of renal embryogenesis. Polycystic kidney. Multicystic kidney.

The permanent kidney develops from two sources (a). The mesonephric duct tissue gives rise to the excretory components (collecting straight tubules, calyces, renal pelvis, ureter). The intermediate mesoderm serves as the primordium for the secretory portion (glomeruli, convoluted tubules).

Initially, an evagination of the mesonephric duct appears—the metanephric diverticulum. Its blind end expands, which subsequently leads to The formation of the renal pelvis (b). As the metanephric diverticulum grows, mesoderm (metanephrogenic tissue) gathers around its distal end. The metanephric diverticulum invades the mass of metanephrogenic tissue (b, c), proliferating to form Major and minor calyces. Each calyx gives rise to numerous outgrowths that become hollow (d) and form the straight collecting tubules of the kidney.

Mesodermal Cells of the metanephrogenic tissue cluster around the growing blind ends (ampullae) of the terminal Branches of the straight collecting tubule system (e) and subsequently transform into a uriniferous tubule. The uriniferous tubule and the collecting duct grow toward each other (f) and soon fuse (g), subsequently developing as a unified system.

If The connection between the straight collecting tubules and the uriniferous tubules fails to occur, the latter develop and begin to secrete, transforming into fluid-filled cysts. The child is born with polycystic Kidneys (i).

Multicystic kidney (j) is rooted in embryogenic disruptions during the earliest stages of organ differentiation. It is believed that this malformation stems from the absence of a normal primordium of the excretory apparatus (h).

Pathomorphological examination of the multicystic kidney reveals a complete loss of typical parenchymal architecture and an absence of functional renal tissue. Only in isolated areas, amidst the Connective Tissue surrounding the cystic cavities, are scattered clusters of rudimentary nephrons found. The cyst walls are composed of fibrous fibers and lined with a single layer of cuboidal epithelium. The fluid within the cavities represents glomerular filtrate subject to a degree of tubular reabsorption. The renal Vascular System features an abundant intercystic capillary network alongside a few thick-walled arterial and venous trunks. The renal pedicle consists of several small vessels.

Clinical presentation. Unilateral multicystic kidney is not accompanied by distinct symptoms. Typically, its sole manifestation is a mass in the corresponding half of the abdomen. The tumor is palpable upon bimanual examination; it is elastic, lobulated, and fairly mobile. Signs of intestinal compression are occasionally observed. Ascites is rarer and may result from cyst rupture into the peritoneal cavity (Knutrud, 1966). When multicystic kidney is combined with severe disease of the contralateral kidney, symptoms of renal failure—such as oliguria and azotemia—dominate the clinical picture.

Diagnosis is based on radiological imaging, beginning with excretory urography. This is performed using elevated doses of contrast media or via an infusion drip technique. Administration of a larger volume of radiopaque solution enhances its concentration within the intercystic vessels, resulting in an X-ray shadow resembling a multilocular soap bubble.

In cases of inadequate renal opacification, cystography or retrograde ureteropyelography is employed to identify associated ureteral anomalies.

Treatment. There is no specific treatment for multicystic kidney disease. A unilateral multicystic kidney must be excised due to the risk of infection or malignant transformation. Patients with bilateral involvement or disease of a solitary kidney are incurable.

Polycystic kidney disease is a prevalent renal malformation. Autopsy data indicate an incidence of 0.2 to 0.4% (A. Ya. Pytel, S. D. Goligorsky, 1968). The condition is characterized by cystic dilation of the tubules, forming cavities that permeate the entire thickness of the renal parenchyma. In 86% of cases, the process involves both kidneys (M. D. Javad-Zade, 1964). A substantial body of evidence has now accumulated, highlighting significant differences between neonatal polycystic kidney disease and that diagnosed in adults. These differences lie in the features of Pathogenesis, pathomorphology, and clinical presentation.

Macroscopically, the abnormal kidneys appear enlarged yet retain their normal contour. Their surface is smooth, rarely lobulated. Sectioning reveals cavities distributed uniformly throughout the cortex and medulla. Alongside microcysts, cavities reaching 6–8 cm in diameter are encountered. Large cysts are sometimes localized in the renal hilum and may compress the organ, disrupting its Blood supply. Such circulatory disturbances can induce nephrogenic Hypertension (M. D. Javad-Zade, 1969). Unlike multicystic kidneys, polycystic cavities lie within properly formed renal tissue, though The amount of functioning parenchyma varies widely and may be minimal. Neonatal polycystic kidney disease is typically characterized by concurrent involvement of other Organs: congenital hepatic fibrosis, cystic Dysplasia of the Pancreas and Lungs, etc.

The clinical presentation is highly polymorphic. The pathological process may remain latent and be diagnosed either during radiological evaluation prompted by the incidental discovery of an abdominal mass, or during routine screening. Complications such as Pyelonephritis, hypertension, and Nephrolithiasis often dominate the clinical picture in older patients. In contrast, neonatal polycystic disease is typically characterized by predominant signs of renal failure, which follows a malignant course and frequently results in mortality.

Diagnosis relies on correlating clinical and radiological findings. Radiographs reveal an increased height of the renal shadow and pelvicalyceal system, abnormal caliceal positioning, elongation of the caliceal infundibula, an increased number of calyces, and semilunar or spherical deformation of their origins, alongside renal ptosis. Calyces frequently acquire bizarre shapes.

These features can be identified through excretory urography. In the event of absent or severely diminished renal function, polycystic disease must be differentiated from all conditions causing a "silent" kidney. Cystography, retrograde ureteropyelography, and renal angiography are performed as indicated. Angiography serves as the concluding diagnostic step and represents one of the most objective investigative Methods. In polycystic disease, the renal artery and its branches are situated at considerable distances from one another, appearing elongated and deformed. The microvascular pattern is attenuated, and avascular zones are present.

Polycystic kidney disease can be treated surgically or conservatively. The latter involves ongoing clinical monitoring with periodic assessment of renal function and the administration of antibacterial therapy if signs of infection appear. In newborns, conservative treatment typically begins with the management of renal failure. This approach comprises a set of measures aimed at stimulating renal activity, correcting Water-electrolyte balance disorders, and restoring acid-base equilibrium. When such symptomatic therapy proves ineffective in the presence of oligoanuria and azotemia, extracorporeal renal replacement therapy is indicated. Surgical intervention is undertaken after acute manifestations of renal failure have been resolved. The surgery of choice is ignipuncture combined with omental wrapping of the kidneys (omentization), which helps improve lymphatic drainage and Blood Circulation.

Hydronephrosis

Hydronephrosis is the dilation of the renal calyces and pelvis resulting from impaired patency of the pelviureteric junction. As a rule, hydronephrosis is accompanied by secondary Atrophy of the renal parenchyma. This condition is among the most common Congenital Malformations of the Urinary System, occurring in children of all age groups. Newborn hydronephrosis has A number of specific features; in particular, strictly congenital forms predominate, in which atrophy of the renal tissue develops primarily during the intrauterine period. By the time of birth, the kidney has undergone profound pathomorphological changes and lost a significant portion of its function. Another feature is The high frequency of bilateral involvement, observed in 1 out of 7 patients (Williams, 1968). Furthermore, the clinical and radiological signs of a bilateral process may not manifest simultaneously. Hydronephrosis in one kidney frequently appears several months or years after it has been diagnosed in the contralateral organ. In such cases, it is not the disease itself that is congenital, but rather its underlying cause.

Etiology AND PATHOGENESIS. The etiological factor consists of anomalies of the pelviureteric junction that impede or completely obstruct the outflow of urine from the kidney. Congenital stenoses are of paramount importance in THE ORIGIN OF neonatal hydronephrosis. Stenosis develops during the Cytology/cytology/16.html">Early stages of embryogenesis due to the abnormal Formation of the wall in the pelviureteric region. The most severe alterations are found within its muscular layer. Histological examination reveals various patterns of muscular hypertrophy. Particularly characteristic is hypertrophy with a circular orientation of the Muscle fibers (Wandschneider, 1966; S. Ya. Doletsky, V. T. Kondakov, 1972). Rare causes of the disease include embryonic adhesions and Valves. The latter represent mucosal folds containing muscular tissue. These valves arise when The Development of the upper section of the ureter—which normally features transverse folds in the fetus—is arrested. A fold that persists into the postnatal period turns into a valve that obstructs renal emptying. Embryonic adhesions originating from the adventitia of the renal pelvis and ureter compress the pelviureteric junction and promote the formation of fixed kinks.

The pathogenesis is based on urine retention within the renal pelvis and elevated intrapelvic pressure. The compression of intrarenal vessels leads to hemodynamic disorders and ischemia of the parenchyma. These two factors play the primary role in the genesis of hydronephrotic renal atrophy. The severity and rate of atrophic changes depend on the degree of development of compensatory-adaptive mechanisms, which include various types of pyelorenal reflux. The more pronounced the obstruction to urine flow, the more intensively hydrostatic pressure rises and the faster renal tissue destruction occurs. Anatomical factors exert a specific influence on the severity of the atrophic process in newborns. With an intrarenal Location OF THE renal pelvis—which is typical for newborns—the pressure of the urine is exerted on the parenchyma surrounding the pelvis from all sides. Naturally, in this case, atrophic changes occur much faster than when the renal pelvis has an extrarenal location. This anatomical feature explains the high frequency of severe forms of hydronephrotic transformation in newborns, in which the bulk of the renal parenchyma is destroyed. The process of renal atrophy is significantly accelerated by the onset of pyelonephritis, which in newborns may present as an acute purulent disease.

The Clinical presentation of hydronephrotic transformation in newborns is largely non-specific, which complicates timely diagnosis. The presence of a palpable kidney may be its sole sign. Infants with hydronephrosis are restless and fail to gain weight properly. Vomiting and fever are observed. If pyelonephritis develops, urinary abnormalities—such as leukocyturia and, less frequently, Hematuria—come to the forefront of the clinical picture.

Radiological findings. Diagnosis is based on radiological examination data. On a plain abdominal radiograph, provided the patient is well prepared, the contour of the enlarged kidney can be visualized. Excretory urography makes it possible to assess the degree of functional Impairment of the organ and sometimes to determine the etiological factor. Insufficient visualization of the Urinary Tract during excretory urography serves as an indication for further investigation, such as cystography, retrograde ureteropyelography, or angiography. Renal angiography via the umbilical Arteries is of particular importance in newborns, as the most severe forms of hydronephrosis occur most frequently at this age, necessitating an accurate evaluation of residual renal function. The detection of a nephrographic phase on angiograms indicates the presence of functioning tissue and the feasibility of organ-sparing surgery; the absence of the nephrogram phase points to complete destruction of the kidney.

Treatment. Establishing a diagnosis of hydronephrosis is an indication for Surgical treatment (Fig. 104). Nephrectomy is performed in cases of total destruction of the renal tissue. The preservation of even minimal function provides grounds for an organ-sparing Procedure. When reconstructive-plastic surgery is impossible due to the patient's critical condition or other reasons, temporary pyelostomy or nephrostomy is employed. Pyelostomy or nephrostomy may be undertaken as The First stage of surgical intervention preceding organ-sparing surgery or nephrectomy in un-

clear cases where doubts persist regarding the complete functional failure of the kidney.

Fig. 104. Types of surgical interventions for hydronephrosis in newborns.

Pyelostomy. The drainage tube is placed subcapsularly (a).

Nephrostomy. The nephrostomy tube is introduced into the renal pelvis through the lower pole of the kidney (b).

Resection of the pelviureteric junction and renal pelvis with ureteropyeloneostomy (final appearance) (c).

The dilated part of the renal pelvis and the stenosed pelviureteric junction have been excised. A new, wide anastomosis has been created between the pelvis and the ureter — the Foley procedure (final appearance). Expansion of the stenosis was achieved by its longitudinal incision and the suturing of a triangular flap, harvested from the wall of the renal pelvis, into the lower angle of the wound (d).

Resection of the pelviureteric junction and renal pelvis combined with Kucera ureteropyeloneostomy is considered the most rational organ-sparing operation in newborns. In early stages of hydronephrotic transformation, with an extrarenal pelvis and a short stenosis (up to 1 cm), flap plasty can be performed. A necessary prerequisite for the surgery is ensuring adequate urine drainage using a nephrostomy or pyelostomy. Intubation of the pelviureteric anastomosis is not indicated in newborns.

Throughout the nephrostomy period, aggressive antibacterial therapy is recommended, since the presence of a foreign body (the tube) within the renal cavity is accompanied by organ infection. The nephrostomy tube is removed on the 6th to 8th day, after the edema of the anastomosis has resolved and the natural passage of urine has been restored, which is verified by dye excretion tests and antegrade ureteropyelography.

Reconstructive-plastic Procedures on the pelviureteric junction prevent the progression of the pathological process and promote the restoration and compensatory enhancement of the function of surviving nephrons. Destroyed renal tissue does not regenerate. Therefore, morphological recovery of the kidney is possible only in the Initial Stages of hydronephrosis. This circumstance underscores the critical importance of timely diagnosis and early organ-sparing intervention.

Terminal stages of hydronephrotic transformation are frequently complicated by pyelonephritis, which tends to become chronic and requires postoperative management. The majority of operated newborns require prolonged, sometimes multi-year, clinical follow-up and treatment for pyelonephritis, including monthly urinalysis and annual radiological monitoring of the renal status.