S y m p o s i u m : Pediatric Surgery-Part II i

Indian J Pediatr 1997; 64:303-312

i

Postnatal Management of Hydronephrosis Diagnosed in Utero Jayant Radhakrishnan and Gonzalo Lievano

Division of Pediatric Surgery and Urology, The University of Illinois, Chi'cago, Illinois, USA Abstract. In this review we identify the causes of antenatal hydronephrosis and detail management options. A large majority of these patients can be treated safely and effectively after birth.

Key Words: Hydronephrosis; Fetal; Neonatal The ahnost " r o u t i n e " use of obstetric ultrasonography since the mid-1970s has resulted in the recognition of congenital anomalies of the fetus with increasing frequency. Fetal h y d r o n e p h r o s i s in particular is easy to recognize and the devastating sequelae of renal damage are well known. It, therefore, appears logical to carry out a n t e n a t a l intervention to prevent postnatal complications. Howevel, as early as 1982 Michael Harrison, a pioneer in fetal treatment, stated "another major problem is how to select out of a large number of fetuses with dilated urinary tracts, only those with obstructions severe e n o u g h to c o m p r o m i s e renal and pulmonary function at birth, and yet not so severe that renal function cannot be salvaged even with decompression. This is the same p r o b l e m we face in trying to decide which n e o n a t e with a d i l a t e d urinary tract needs surgical treatment. It is

Reprint requests: Jayant Radhakrishnan, Professor of Surgery and Urology, Chief of Pediatric Surgery, The University of Illh~ois,2454 E. Dempstel; Suite 406 Des Plaines, IL 60016 USA.

obvious that the fetus with a dilated lowpressure system who continues to have good urinary output and adequate amniotic fluid volume requires no intervention. At the other end of the spectrum, the fetus with severe renal dysplasia that is not reversible even with decompression, does not warrant treatment. And the fetus with unilateral disease of any type with a normal functioning contralateral kidney can be m a n a g e d c o n s e r v a t i v e l y b e c a u s e the disease is not life threatening. It should be clear that most fetuses with urinary tract disease require no t r e a t m e n t . ''1 Fetal intervention is also not warranted when associated life threate~!~g anomalies or chromosomal abnormalili,~.s are detected. Furthermore, if hydronephrosis is detected after 33 weeks of gestation and the fetus has m a t u r e lungs, early d e l i v e r y and postnatal management rather than prenatal i n t e r v e n t i o n is i n d i c a t e d . A n t e n a t a l intervention should, therefore, only be reserved for patients with deteriorating but normal or near normal renal functions as identified by volume of amniotic fluid,

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biochemistry of fetal u r i n e and ultrasonography of the fetal kidney (Table 1). 2"4 Unfortunately, even with very careful selection, the results of fetal intervention are poor to date. 5 T a b l e 1: P r e d i c t i v e Value of Fetal Studies C o n g e n i t a l O b s t r u c t i v e U r o p a t h y 2, 3, 4 Test

Amniotic Fluid

Renal Function Poor Good

Decreased

Renal Sonography - Cortical + cysts - Cortical Increased echogenicity Sodium >100 0nEq/L) Chloride >90 (mEq/L) ~2 Microglo>2 bulin ( m q / L ) Calcium . >8 (mg/dL) Total proteins >20 (mg/dL) Osmolarity >210

in

Predictive Value Sensi-Specitivity ficity

Normal

Mild oligohydramnion has poor predictive value

Normal

44%

Normal

Poor accuracy

--

100%

<100

82%

--

64%

<90

70%

--

62%

<2

80%

--

83%

<8

53%

--

84%

<20

65%

--

89%

<210

ANTENATAL HYDRONEPHROSIS Once fetal pyeliectasis is identified one must first define whether it is physiologic or pathologic since 41% of normal fetuses may have detectable pelvic fluid and 18% m a y have pelvic distention. 6 Mild or physiologic h y d r o n e p h r o s i s appears to resolve without affecting renal functional development. 79 Arger et al ~~have suggested that a pelvic diameter >10 mm and a ratio of anteroposterior pelvic to renal diameter >50% indicates significant fetal hydronephrosis. For the fetus younger than

1997; Vol. 64: N o . 3

33 weeks of gestation, Corteville e t al 8 suggest that the t h r e s h o l d of the AP diameter should be >4 mm to achieve 100% sensitivity in identifying significant lesions. To the above criteria, Kleiner et al have a d d e d caliectasis as an i n d i c a t o r of significant hydronephrosis. 11The incidence of false p o s i t i v e d i a g n o s i s of "fetal h y d r o n e p h r o s i s r a n g e s from 9-39% of cases2218 Furthermore, a careful follow-up of all cases is imperative since minimal h y d r o n e p h r o s i s on an early scan m a y progress in a significant number of fetuses 819 and the severity of hydronephrosis may v a r y g r e a t l y d u r i n g the c o u r s e of gestation. 2~ We believe that Gloor 4 has p r o p o s e d an excellent a l g o r i t h m for managing fetuses with hydronephrosis (Fig. 1).

Classification of Lesions Resulting in Fetal Hydronephrosis Each lesion could be unilateral or bilateral 1. Cystic lesions a. Multicystic dysplastic kidney (MCK) b. Infantile polycystic kidney disease (IPKD) 2. Non-obstructive lesions a. Transient hydronephrosis b. Vesicoureteric reflux (VUR) c. Complete renal duplication 3. Possibly obstructive lesions a. C o m p l e t e renal duplication with ureterocele b. Prune belly syndrome (PBS) 4. Obstructive lesions a. Ureteropelvic junction obstruction (UPJO) b. Primary Obstructive megaureter c. Posterior urethral valves (PUV)

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Algorithm Describing Management of Fetus With Prenatally Detected Hydronephrosis. (reprinted with permission from Gloor, .IN, Mayo Clin Proc 199530:145-152)

Fetal Hydronephrosis /

N Bilateral

Unilateral

$

$

Advanced-level ultrasonography Fetal echocardiog,raphy Analysis of fetal karyotyl~

No intervention Routine obstetric care Postnatal evaluation and treatment

$ Detection of lethal abnormality / No

Yes

$

$

Oligohydramnios present

No intervention Counseling /

N No

Yes

$

$

Serial ultrasonography

$ Good prognostic group / Yes / Lungs Mature

Yes

Delivery Postnatal evaluation and treatment

V[ C-- I J

N

Fetal renal -q ultrasonography Serial fetal urinalyses ~Rate of fetal urine production

No N No intervention Counseling

No

Decompression in utero Delivery at term or pulmonary maturity Postnatal evaluation and treatment

Fig.: 1

Development of oligohydramnios

Yes

No Delivery at term Postnatal evaluation and treatment

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Postnatal Evaluation of Antenatal Hydronephrosis It is important to remember that one cannot extrapolate data from prior experience with s y m p t o m a t i c p a t i e n t s to these as)anptomatic newborns who are diagnosed by antenatal ultrasonography. Figure 2 presents an a l g o r i t h m that we use to evaluate and manage these patients after birth. The initial renal ultrasound is carried out in a well hydrated infant within 48 to 72 hours of birth. Since at birth, the infant is often oliguric with a low glomerular filtration rate, it is possible to have a normal initial postnatal ultrasound with eventual redevelopment of hydronephrosis2 ~24 If the initial ultrasonographic study is normal, we repeat it at one month and if it is again normal it is repeated at three months. Once the three-month study is normal, we repeat the next study at one year of age and if that is also normal we follow with clinical observation. If, at any time, the renal ultrasound demonstrates any degree of h y d r o n e p h r o s i s we obtain a v o i d i n g cystourethrogram (VCUG) to rule out VUR and a renal scan to determine renal function and drainage. In the neonate we usually do not carry out the initial renal scan for 3-4 weeks while we await the development of adequate renal function. We prefer the MAG 3 renal scan with a draining bladder catheter in place. This radioisotope not only identifies functioning renal tissue and is useful in determining differential function but a post-furosemide renogram is valuable in evaluating an obstruction. A T89 max of <10 minutes is considered normal whereas a T89 max of >20 minutes is considered o b s t r u c t e d . 2s All patients with hydronephrosis of any degree, whether or not t h e y h a v e VUR, are placed on

prophylactic antibiotics until the problem is resolved, either spontaneously or with the treatment. We initially use an antibiotic of the penicillin group and after 6 weeks change to sulfa drugs.

Neonatal Ultrasound

/

Normal

\

Hydronephrosis

Ultrasound 1 month

$

~VCUG and Renal Sca n

Normal

$ Ultrasound 3 mo

$ Normal

$

Obstructed

$ Surgery

Nonobstructed

$

Follow-up with scans

UltrasomM 1 year

$ Normal

$ Clinical Observation Fig. 2: Algorithm for Postnatal Management of Antenatally Diagnosed Hydronephrosis.

MANAGEMENT OF SPECIFIC LESIONS

Cystic Lesions

Multicystic dysplastic kidney (MCK): Unilateral MCK requires no intervention in the fetus. In the rare bilateral case, the fetus succumbs to the sequelae of oligohydramnios. After birth, there may be a clinically palpable lobulated flank mass. Antenatal and postnatal ultrasonography

1997; Vol.64: No. 3 demonstrate multiple fluid filled lesions in the kidney which have the appearance of a "bunch of grapes". No renal parenchyma is visualized nor is the ureter visible. A renal scan demonstrates a photopenic area on the affected side. The natural history of MCK is one of spontaneous resolution. 26 However, it is important to follow these kidneys with sequential ultrasonographic evaluations until complete resorbtion occurs since a dysplastic cystic kidney may have a similar appearance on initial ultrasonography but it will not resorb. A follow-up until complete resorbtion is als0 r e q u i r e d since the d e v e l o p m e n t of hypertension, malignancy and infection in the kidney have all been reported with MCK. If the k i d n e y has not resorbed completely in one year, then we carry out a nephrectomy.

Infantile Polycystic Kidney Disease (IPKD): The infantile form of polycystic kidney disease is almost uniformly fatal due to pulmonary and renal failure in the neonate. These fetuses develop larger, echogenic bilateral renal masses and oligohydramnios. Antenatal intervention is not indicated since the renal pathology cannot be reversed. At birth, they have firm b i l a t e r a l flank m a s s e s w h i c h on ultrasonography appear solid rather than cystic. The ureters are not visible and the bladder is empty. These infants are critically ill at birth. The u l t r a s o n o g r a p h i c appearance of IPKD is similar to that of nephroblastomatosis but in the latter the urine output is generally adequate. A renal scan generally demonstrates minimal, if any, perfusion to the kidneys. We feel that aggressive management of these children is not indicated. If one decides to treat them p o s t n a t a l r e s p i r a t o r y s u p p o r t and peritoneal dialysis are required. However,

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these massive kidneys leave very little peritoneal cavity for dialysis. Hence, bilateral n e p h r e c t o m y as a prelude to peritoneal dialysis can be carried out. 27 NON-OBSTRUCTIVE LESIONS

Transient Hydronephrosis: T r a n s i e n t hydronephrosis is postulated to be due to either a high glomerular filtration rate in the fetus which is never matched after birth or the effect of maternal hormones on urinary smooth muscles of the fetus. It could also be due to transient obstruction from renal vessels during the ascent of the kidney to its final position. However, the diagnosis of transient hydronephrosis is only made by exclusion when follow-up u l t r a s o n o g r a p h y a n d / o r renal scans continue to be normal. Vesicoureteric Reflux (VUR): Vesicoureteric reflux has been reported in as many as 40% of fetuses at birth. 28, 29 Of course, no antenatal treatment is indicated for these fetuses even if the diagnosis were made. The initial p o s t n a t a l u l t r a s o u n d m a y demonstrate hydronephrosis and the ureter can sometimes be visualized behind the bladder. The VCUG, of course, makes the diagnosis of VUR. These patients are placed on suppressive antibiotics and reflux is managed by the principles that are now well known. Complete Renal Duplication: This will be discussed with renal duplication with ureterocele. POSSIBLY OBSTRUCTIVE LESIONS

Renal Duplication with Ureterocele: Massive cystic dilation of a completely

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duplicated system occurs from time to time whether or not a ureterocele is present. To our knowledge, this has never resulted in dystocia or respiratory distress after birth. Generally, the dysplasia and dilation affect the upper pole of the kidney which drains via a dysplastic megaureter. The orifice of this ureter could be normal, ectopic or it may end in a ureterocele. Antenatal and postnatal renal ultrasonographic examinations demonstrate an extremely dilated renal pole (usually upper) with almost no renal parenchyma. The large and tortuous ureter may be visualized in the pelvis behind the bladder. If a ureterocele is present its wall can be defined within the bladder. Generally, the lower pole of the kidney is normal but its ureter tends to reflux. At birth an abdominal mass may occasionally be palpated. If the lower pole ureter refluxes the calyces will'typically have the appearance of a drooping lily on a V C U G . g~ These patients should be left on suppressive antibiotics and at 3-4 weeks a renal scan should be carried out to evaluate function of tSe affected pole of the kidney. In general, dysplasia and dilation due to dysmorphism exist in these patients rather than a true obstruction. If the ureterocele is o b s t r u c t i v e it s h o u l d be i n c i s e d cyst0scopically and adequate drainage of the renal m o i e t y ensured. In patients without obstruction a careful follow-up is r e q u i r e d . If the affected s e g m e n t demonstrates adequate function it should be preserved, g~ Prune Belly Syndrome (PBS): Patients with PBS have large thick walled bladders that m a y extend up to the umbilicus and massive m e g a u r e t e r s and d y s m o r p h i c hydron e p h ro tic kidneys along with bilaterally undescended testes. Antenatally, dilated dysmorphic kidneys with massive

tortuous megaureters visualized well into the pelvis along with a large thick walled bladder are noted. After birth the typical appearance of the child makes the diagnosis simple. Most patients with prune belly syndrome do not require acute surgical care since their depressed renal function is due to renal d y s p l a s i a r a t h e r t h a n true obstruction. Those few patients who have a true obstruction develop renal failure early and m a y require c u t a n e o u s pyelostomies to prevent rapid failure of the kidneys. If they respond well to cutaneous pyelostomies they should be undiverted after one year of age and at that time a complete reconstruction of the urinary tract can be carried out. This will help with e v e n t u a l renal t r a n s p l a n t a t i o n . Many patients with PBS have VUR or simple stasis. They are treated with suppressive antibiotics and followed carefully for deteriorating renal functions. If recurrent infections occur, total reconstruction of the urinary tract m a y be of value. In PBS patients, who do not require reconstruction of the urinary tract, bilateral orchiopexy with or without associated abdominoplasty should be carried out by two years of age.

308

OBSTRUCTIVE LESIONS

Ureteropelvic Junction Obstruction (UPJO): UPJO is the m o s t c o m m o n c a u s e of hydronephrosis in the fetus. In the past, immediate surgical correction was c o n s i d e r e d to be the t r e a t m e n t of choice.3~ However, this recommendation was based upon extrapolation of experience with symptomatic patients to asymptomatic antenatally diagnosed patients. In 1988 Dejter and Gibbons 36first demonstrated that these babies could be watched safely and operated upon at a later date. In addition,

1997; Vol.64: No. 3 they identified two patients in whom the initially obstructive pattern on renography improved to a point that they did not r e q u i r e s u r g i c a l t r e a t m e n t . Koff and Campbell in 199437 carried this evaluation further by following 104 patients with unilateral hydronephrosis for five years. They f o u n d that only seven required p y e l o p l a s t y for d e t e r i o r a t i n g renal functions. Furthermore, after pyeloplasty, renal function returned to its previous level in all the kidneys. Since then emergent surgical management of UPJO is no longer carried out and these patients are evaluated with renal scans. We have chosen to operate if a c l e a r l y o b s t r u c t i v e p a t t e r n is demonstrated at three months, on the other hand others feel that surgical correction should be delayed until differential function on the affected side drops to 35% of the total function.38 Of course, in patients with bilateral UPJO one must be more careful and most authors would agree that a clearly o b s t r u c t e d scan at three m o n t h s is indicative for of the need for surgical correction. On ultrasonography, a large renal pelvis and d i l a t e d calyces are visualized in these patients but the ureter is not visible. An abdominal mass may or may not be palpable in the neonate. After an initial VCUG to rule out VUR, the patient is evaluated with renal scans. We still carry out an IVP prior to surgery to delineate the anatomy but other authors feel that an IVP is unnecessary. Primary Obstructive Megaureter: These babies u s u a l l y do not h a v e a clearly demonstrable abdominal mass. Antenatal and postnatal ultrasonographic evaluations demonstrate not only a hydronephrotic kidney but a large tortuous ureter all the w a y d o w n into the pelvis behind the

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bladder. A VCUG will rule out reflux and a renal scan will clarify the degree of obstruction. In patients with an obstructive megaureter, the megaureter can take the brunt of the back pressure and protect the kidney. Hence, as in the case of UPJO, some patients with m e g a u r e t e r can also be watched s a f e l y . 39' 40 However, in contrast to patients with UPJO, a significant number of these patients require surgical treatment. Liu et aI4~ followed up 67 megaureters for approximately three years. Thirty-four per cent of these resolved spontaneously while 49 per cent persisted. In addition, another 11 (17%) r e q u i r e d s u r g i c a l t r e a t m e n t because of a break through infections in three and deteriorating function in eight. Obstructive megaureters also differ from UPJO since any deterioration in renal function persists after surgical correction. Liu et al f o u n d that patients with an ultrasonographic ureteric diameter <6 mm did well when watched non-operatively whereas those with a diameter >10 mm did poorly. Posterior Urethral Valves (PUV): By far the most problematic of all patients with antenatally diagnosed hydronephrosis are those with posterior urethral valves. At b i r t h m a n y of these p a t i e n t s h a v e respiratory failure and a suprapubic mass. Ultrasonography, antenatally and postnatally, will d e m o n s t r a t e bilatcral hydronephrosis and megaureters extending down into the pelvis. The bladders are thick walled but unlike those of patients w~th PBS, they have a fairly small capacity. With current u l t r a s o n o g r a p h i c techniques a dilated posterior u r e t h r a m a y also be visualized. An initial VCUG makes the diagnosis and placement of a b l a d d e r catheter per urethra almost always resolves

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the emergency. H o w e v e l , patients with very severely affected m a s s i v e atonic ureters are unable to p r o p e l the bolus of urine. Some of t h e s e p a t i e n t s r e q u i r e s u p r a v e s i c a l u r i n a r y diversion. O u r choice is to carry out bilateral c u t a n e o u s p y e l o s t o m i e s since this c o m p l e t e l y b y p a s s e s the atonic ureters, gives a large orifice for d r a i n a g e of urine and at the t i m e of u n d i v e r s i o n at a later age it is the easiest to take d o w n w i t h o u t losing the b l o o d s u p p l y of the distal ureter. .PUV patients in w h o m the s e r u m creatinine does not d r o p b e l o w one rag% i m m e d i a t e l y u p o n t r e a t m e n t generally do v e r y p o o r l y in the long run. 4~,4~ Patients with a " p o p off" m e c h a n i s m in the f o r m of unilateral VUR with renal dysplasia, a large congenital b l a d d e r d i v e r t i c u l u m or u r i n a r y e x s t r a v a s a t i o n w i t h or w i t h o u t u r i n a r y ascites g e n e r a l l y do well. 43

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CONCLUSION Thus, most patients with antenatal h y d r o n e p h r o s i s can be w a t c h e d carefully through p r e g n a n c y and treated after birth. Postnatal management commences with i m m e d i a t e e v a l u a t i o n and a careful followup w i t h i n d i v i d u a l i z e d t r e a t m e n t for each abnormality. REFERENCES

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DISEASES ON THE WAY OUT Amidst the continuing outbreaks of the dreaded diseases, a few will hopefully be eliminated from the face of the earth. Poliomyelitis is targeted for global eradication by the year 2000. There are now 145 countries completely free of the diseases. Leprosy is steadily being defeated and is not expected to be a significant public health problem in a few years' time. Guinea-worm disease (dranculiasis) is also well on the way to eradication. Since 1986 the no. of cases worlwide has fallen from 3.5 million to about 120,000. River blindness (onchocerciasis) caused by a parasite that is carried by blackflies, is being eliminated from 11 West African countries. Chagas disease, a disabling disease that can cause heart damage and death in chronic sufferers, is being eliminated from Argentina, Bolivia, Brazil, Chile, Paraguay and Uruguay. Abstracted from: World Health, Jan-Feb. 1997, pp. 28.