Email: aditisinhaaiims gmail. Widespread antenatal screening has resulted in increased detection of anomalies of the kidneys and urinary tract. The present guidelines update the recommendations published in Antenatal hydronephrosis ANH is transient and resolves by the third trimester in almost one-half cases.
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With the increasing use of ultrasonography, congenital anomalies are often picked in utero. Antenatally detected hydronephrosis is amongst the most commonly detected abnormality.
The management of this condition has raised considerable debate amongst clinicians dealing with it. This article is written with an idea to provide comprehensive information regarding the postnatal management of antenatally detected hydronephrosis. A detailed review of the current literature on this topic is provided. Also, guidelines have been given to facilitate the management of this condition.
Core tip: This article provides practical guidelines for the postnatal management of antenatally detected hydronephrosis. The detection of renal abnormalities during prenatal ultrasonography was first reported by Garrett et al [ 1 ] in Since then routine use of ultrasonography for detection of congenital anomalies has become a part of routine care during the antenatal period.
Thus we have an increasing number of patients who are presenting to the clinician with a presumptive diagnosis rather than a symptom and that too before they are born [ 4 ]. Logic dictates that this early detection should help in improving post natal outcomes and help in better preservation of the renal function. Hence a thorough postnatal evaluation of the upper and lower tracts is mandatory postnatally. This is borne out by various studies showing that the most common cause of antenatally detected hydronephrosis is transient or non obstructive dilatation of the pelvicalyceal system [ 6 , 7 ].
Thus, postnatally, the clinician is faced with dilemma to differentiate the hydronephrosis which will resolve spontaneously from the one which will become clinically significant and would need surgery. This differentiation needs to be done by utilizing appropriate investigations using the lowest radiation and least invasive techniques so that timely surgical intervention can be done, in those who need it, to prevent renal function deterioration [ 4 ].
This article reviews the primary literature and consensus statements pertaining to antenatally detected hydronephrosis and sets forth our own recommendations regarding management of infants with this finding.
The diagnosis of fetal pelvis dilatation and its natural history postnatally is best understood if we understand that the definition of hydronephrosis has undergone a sea change. Traditionally hydronephrosis was defined as dilatation of the pelvicalyceal system due to partial or complete obstruction.
Now clinicians understand that hydronephrosis is aseptic dilatation of the collecting system and it may or may not be associated with obstruction. Investigators have proposed that the term pyelectasis be used to describe dilatation of renal pelvis whereas pyelocaliectasis and hydronephrosis include dilatation of calyces. However, all these three terms are used interchangeably and are used to describe a dilated pelvicalyceal system regardless of its etiology [ 8 ].
The antenatal ultrasound screening is most commonly performed at wk of gestation. This is the time when the renal architecture becomes visibly distinct. Normally the renal pelvis and calyces are not seen, if seen then it indicates hydronephrosis. The sonologist should be vigilant in the antenatal period to differentiate a dilated collecting system from the hypoechoic sonolucent pyramids which may mimic hydronephrosis. Once the diagnosis of a dilated collecting system is made, it should be objectively described using one of the various classification systems.
With the sophisticated ultrasound machines with better resolution detecting smaller dilatations of the renal pelvis, the cut off value of the renal pelvis dilatation necessitating cognizance and achieving clinical significance has been a matter of debate. In , Mandell proposed a classification system based on APD and gestational age that helps to categorize antenatal hydronephrosis in the mild, moderate and severe variety [ 9 ].
This was further substantiated by the work of Corteville et al [ 10 ] and should now be taken as a standard classification of antenatal hydronephrosis based on APD [ 11 , 12 ]. Recently cut off of 6 mm at 20 wk and 10 mm at 30 wk have been suggested for pyelectasis and an APD cut off of 10 mm at 20 wk and 12 mm at 30 wk for hydronephrosis [ 15 ].
An interesting feature of this study has been the effort to separate pyelectasis from hydronephrosis so that postnatal ultrasound can be avoided in a number of patients. However given the subjective nature of sonography and the factors like maternal hydration affecting the measurements, this issue has not been resolved as of today and hence clinicians should follow a standard classification and grade the dilatation as mild, moderate and severe as suggested in Table 2.
Another classification used to describe hydronephrosis is the Society of Fetal Urology classification which was first described in [ 16 ]. This system describes the renal pelvis dilatation along with the dilatation of the calyces and hence its effect on the parenchyma Table 3.
However this grading system is not universally followed and due to the ambiguity in inter and intra observer agreement especially in grade 3 and grade 4 hydronephrosis, modifications have been proposed [ 17 , 18 ]. Even these modifications have not gained universal acceptance. Given these discrepancies, it is imperative that worldwide a uniform system of classifying and grading hydronephrosis should be followed. In order to overcome these variations and negate the effect of hydration and full bladder, group from Hong Kong has proposed a Hydronephrosis Index and have given nomograms to help clinicians judge the degree of renal pelvic dilatation based on the gestational age [ 19 ].
The hydronephrosis index is defined by the APD of the fetal kidney divided by the urinary bladder volume.
It is an interesting index but its clinical usefulness and specificity in fetuses with abnormally dilated renal pelvis or gross hydronephrosis is not established. Till a reliable method is described, which overcomes the variables of maternal hydration, bladder fullness of fetuses and the operator dependency, clinicians should mention the method used to diagnose antenatal hydronephrosis and grade its findings.
If the APD is used than the presence or absence of associated calyceal dilatation should also be mentioned. These additional findings often contribute to establishing the postnatal diagnosis [ 20 ]. In cases of posterior urethral valves the level of amniotic fluid is a significant predictor of renal function and clinical outcome [ 21 ]. Currently, there is no agreed upon protocol for the antenatal evaluation and its follow up. The first anomaly scan is done usually between wk, this should reliably diagnose antenatal hydronephrosis.
The subsequent frequency of follow up ultrasound is often based on the severity of findings and the pathology suspected. There is usually no added advantage of doing very frequent ultrasound examinations for it adds very little to the diagnosis and subsequent management and only aggravates parental anxiety. Once the diagnosis is made then the next ultrasonography can be done in the third trimester between wk.
However more frequent ultrasounds, every wk, will be needed in cases having bilateral hydronephrosis, posterior urethral valves, prune belly syndrome and severe hydronephrosis in a solitary kidney.
Ultrasound findings in these clinical scenarios have an important bearing on the decision making in deciding the obstetric course of the patient. Once the diagnosis of ante natal hydronephrosis ANH is made, the parents are engulfed by a myriad of emotions.
The two important things that the clinician is often asked to answer is-Should antenatal intervention be done and what happens postnatally. Addressing the parental anxiety and concerns is as important as the clinical management of the child. Studies have shown that urinary obstruction can cause renal dysplasia and relief of that obstruction can prevent dysplasia if performed early enough [ 22 ].
The goal of fetal intervention would be to relieve this obstruction and allow for normal renal development. This in turn would maintain the amniotic fluid levels to allow for normal lung development. Currently, fetal intervention is recommended for those with documented lower tract obstruction, the commonest and most widely studied being posterior urethral valves, where intervention would significantly benefit the overall fetal and its renal function prognosis.
Open fetal surgery, vesico-amniotic shunt, renal pelvis aspiration, vesicocentesis, fetoscopic fulguration of posterior urethral valves etc have been tried. Though this sounds fascinating, its attendant problems and risks cannot be overlooked.
Also does it alter the prognosis significantly and does the benefit outweigh the risks should be evaluated diligently. At present fetal intervention is indicated in cases where the life of the fetus is at risk, typically a second trimester fetus with significant oligohydramnios, suspected good renal function and absence of other life threatening anomalies [ 21 ].
However, this is often too late to prevent renal dysplasia. The procedure is associated with significant risk of infection and also significant fetal and maternal morbidity and fetal mortality [ 23 , 24 ]. Thus, except in a select few cases fetal intervention should not be done and even these cases should be done in centres where the necessary expertise and experience is available. When the diagnosis of ANH is made the parents often have apprehension that the child will need surgery postnatally [ 25 ].
They need to be assured and often a session of counseling with the pediatric urologist who will be taking care of the child postnatally goes a long way to allay the apprehensions of the parents. What should be emphasized that though there is no cause for alarm in majority of cases, a proper and rigorous follow up is a norm in majority of the cases.
Since infants are relatively dehydrated at birth, the initial postnatal ultrasonography should be performed after 48 h of birth. Day two of life is preferred to enable adequate hydration after delivery but circumstances pertaining to early discharge following delivery may not allow this. Also breast fed neonates may not be adequately hydrated until a steady milk flow is established. Hence the first postnatal ultrasound is preferably done between d after birth [ 12 , 26 , 27 ].
The exceptions to this caveat are: 1 Suspected lower tract obstruction e. Early sonography in these situations has obvious bearing on further management. Whenever there is hydronephrosis the treating clinician is worried about two things-obstruction and infection. The obstruction needs to be established in most cases with ANH. However the clinician is worried about the possibility of infection in a dilated system with stasis of urine.
So, should neonates and infants with ANH be put on antibiotic prophylaxis? Till date there are no prospective studies providing level I evidence to support the use of prophylaxis.
The available literature is conflicting. Studies have shown that the risk of infection increases with the degree of hydronephrosis [ 28 - 31 ]. Girls appear to be at greater risk than boys [ 29 ]. However these studies are observational in nature and not standardized as regards, the method of urine collection, definition of infection, selection of patients for voiding cystourethrogram and use of prophylactic antibiotics.
More and more data is coming regarding the limited usefulness of prophylactic antibiotics and with the varying practice patterns due to variations in geographic location, clinician experience and above all variable health care practices in developing countries, as of yet, no standardized uniform guidelines have been proposed.
However undeniably patients with mild hydronephrosis are at much less risk of infection as compared to those with moderate to severe hydronephrosis [ 12 , 32 - 36 ]. Based on the available evidence we propose the following to be done within the first 48 h after birth in neonates born with antenatally diagnosed hydronephrosis Table 4. All infants detected to have ANH should be evaluated by a postnatal ultrasound, which is usually done at d after birth [ 11 , 37 ] for the reasons described above.
The following should be the aim of doing this evaluation using a tool which is easily available, provides good anatomical information, is non invasive and is not associated with any radiation: 1 Confirm the presence of hydronephrosis; 2 Grade the degree of hydronephrosis; 3 Plan further tests and evaluation and management strategies based on the ultrasound findings; and 4 Decide the need for antibiotic prophylaxis. The ultrasonography should be done with the baby being well fed.
It is the practice of one of the authors Sharma A to start the examination of these babies by scanning the bladder first. If the bladder is full, usually the baby voids and the degree of bladder emptying is known immediately giving a fair idea regarding the absence of outflow obstruction.
Also once the bladder is empty, the effect of a distended bladder on the filling and emptying of the collecting system resulting in fallacious diagnosis of pyelectasis is avoided.
The mechanism by which a full bladder causes dilatation of the renal pelvis and the maximal degree of normal dilatation is not known. However it is accepted that when urinary bladder is distended than false positive cases may occur [ 19 ]. Hence if a sonologist sees mild degree of hydronephrosis than whether it persists or disappears after bladder emptying should be looked for and mentioned in the report. Ultrasonography at d would show one of the following scenarios: 1 No hydronephrosis-Normal pelvicalyceal system; 2 Unilateral hydronephrosis; 3 Bilateral hydronephrosis; 4 Unilateral Hydronephrosis with hydroureter; and 5 Bilateral hydronephrosis with bilateral hydroureter.
Let us see each scenario and discuss its management. Why this happens is a matter of speculation. Constantinou [ 39 ] suggested that a pacemaker in the renal pelvis activates the smooth muscle of the renal pelvis to initiate peristaltic contractions.
Revised guidelines on management of antenatal hydronephrosis
With the increasing use of ultrasonography, congenital anomalies are often picked in utero. Antenatally detected hydronephrosis is amongst the most commonly detected abnormality. The management of this condition has raised considerable debate amongst clinicians dealing with it. This article is written with an idea to provide comprehensive information regarding the postnatal management of antenatally detected hydronephrosis. A detailed review of the current literature on this topic is provided.
Revised Guidelines on Management of Antenatal Hydronephrosis
Use of antenatal ultrasound for evaluation of congenital anomalies in early pregnancy has become a common practice. Hydronephrosis is the most common anomaly observed. Urologists are being referred such cases more frequently. Prenatal intervention is experimental and being done in advanced centers.
Widespread antenatal screening has resulted in increased detection of anomalies of the kidneys and urinary tract. The present guidelines update the recommendations published in Antenatal hydronephrosis ANH is transient and resolves by the third trimester in almost one-half cases. The presence of oligohydramnios and additional renal or extrarenal anomalies suggests significant pathology. Infants with VUR should receive antibiotic prophylaxis through the first year of life, and their parents counseled regarding the risk of urinary tract infections. The management of patients with pelviureteric junction or vesicoureteric junction obstruction depends on clinical features and results of sequential ultrasonography and radionuclide renography. Further studies are necessary to clarify the role of prenatal intervention, frequency of follow-up investigations and indications for surgery in these patients.
Subscription Recommendations. Correspondence to: Dr. E-mail: arvindbagga hotmail. Dilatation of the fetal urinary tract is increasingly being recognized with wide-spread use of fetal scanning, sophistication of ultrasound equipment and greater expertise. The pediatrician is often faced with managing infants with asymptomatic hydronephrosis, which was detected in utero. In most instances, mild to moderate dilatation of renal pelvis resolves after birth.