Dr. Priyanka Shukla has done M.B.B.S from Kanyakumari Govt. Medical College and M.S in Obstetrics and Gynaecology from Lady Harding Medical College. She has received various distinctions and gold medals in her academic career. She also received best outgoing postgraduate student award in LHMC. This research paper is a part of her thesis dissertation with Professor Manisha Kumar as her guide.
Aim : To determine the role of antenatal parameters in predicting the outcome of bilateral fetal hydronephrosis.
Methodology : Total 50 antenatal women with bilateral antenatal fetal hydronephrosis (ANH) were included. On ultrasound, amount of liquor, kidney size, pelvic anteroposterior diameter, degree of caliectasis, bladder size, and thickness were observed at 28 and 32 weeks of gestation. For 3 months post-delivery, the babies were evaluated in terms of ultrasound renal parameters, serum creatinine levels, and need for surgery.
Results The mean gestational age at delivery was 37.4 ± 1.7. All babies were alive at birth, 48 were alive after 3 months. Surgery was done in 10/50 cases; cystoscopic fulguration was the most common procedure. There was a resolution of bilateral ANH in 27/50 cases, in 5/50 cases there was pylectasis with normal serum creatinine, and in 18/50 cases there was adverse outcome. Most of the parameters had better sensitivity and specificity at 32 weeks than at 28 weeks. At 32-week gestation, the renal pylectasis between 10 and 15 mm had the highest sensitivity (88.9%), and the presence of caliectasis had the highest specificity (90.6%) for adverse outcome.
Conclusions: Resolution of hydronephrosis took place in the majority of cases, and there was an adverse outcome in only one-third of them. Renal caliectasis was the best marker for the prediction of adverse outcome.
Keywords Pylectasis · Bilateral renal anomaly · India · Survival after birth · Hydronephrosis · Caliectasis · Prospective study
With the advent of good-quality ultrasound (US) screening
during pregnancy, there has been an increase in the recognition
of fetal hydronephrosis in recent years. The prevalence
of antenatally detected hydronephrosis (ADH) ranges from
0.6 to 5.4% [1], bilateral affection is seen in 17–54% cases
and are occasionally associated with additional abnormalities
also [2]. It has been observed in previous studies that in
the majority of cases, fetal hydronephrosis reverts back to
normal in due course, and hence, excessive concern regarding
the ultrasound finding often leads to parental anxiety and
unnecessary testing of the newborn. The prenatal management
should be directed toward identifying those in which
fetal hydronephrosis may adversely affect the health of the
infant and require antenatal and postnatal evaluation, timely
referral to a pediatric urologist if required, and possible
intervention to minimize adverse outcomes, while limiting
testing in those cases that are due to a benign, transient
condition. This prediction would be of help to fetal medicine
specialists and obstetricians who deal with these cases
antenatally.
There is reasonably large body of existing medical literature
on prenatal hydronephrosis [3, 4, 5] but, most of these
studies include fetuses with both bilateral and unilateral hydronephrosis. The bilateral hydronephrosis is different
from unilateral as it has worse prognosis due to involvement
of both kidneys and because of the presence of lung hypoplasia
as sequelae of oligohydramnios. There is paucity of
data on outcome of bilateral ANH. Although there is a relatively
robust body of work on the retrospective analysis of
prenatal hydronephrosis and its postnatal correlates [3, 4, 5],
but there is paucity of prospective research on the subject. A
prospective study provides a true picture of natural course of
the disease, and this is especially true for pylectasis as there
is a high probability of reverting to normal after delivery.
A prospective study on bilateral ANH was therefore
undertaken to observe the natural course of bilateral fetal
hydronephrosis antenatally and to track its postnatal progression
till 3 months of age. The study also intended to evaluate
the role of antenatal ultrasound parameters to predict the
outcome of bilateral ANH.
This Prospective observational study was done at from
November 2016 to April 2019 after ethical clearance from
institute’s ethical committee (IEC). The study included pregnant
women with bilateral fetal hydronephrosis on antenatal
ultrasound (US) at or before 28 weeks of gestation after
obtaining a written informed consent. Hydronephrosis was
defined as the renal APD diameter was more than 7 mm in
the bilateral kidneys at 28 weeks ultrasound [5]. All women
with unilateral hydronephrosis or with other associated
non-urinary structural anomalies were excluded as it would
impact on the amount of liquor and the outcome.
All US was done by single person, using US machine
Nemio XG (Toshiba, Japan), with 3–5 MHz probe. The
parameters amniotic fluid index (AFI), kidney length and
width, anteroposterior pelvic diameter, and caliectasis were
observed at 28 weeks and 32 weeks in all women. An amniotic
fluid index, less than the 2.5th percentile for that gestational
age was considered to be oligohydramnios [4]. The
APD was measured in transverse axial image of the renal
pelvis at level of the renal hilum. The dilatation of secondary
renal calyces was termed as caliectasis. The length of bladder,
thickness of bladder wall, dilatation of ureter was noted.
The women were followed up till delivery. At delivery, the
baby’s birth weight, APGAR were observed.
All live babies were evaluated by a team of pediatric surgeons,
the management was provided as per hospital protocol.
It included postnatal kidney and bladder US, serum
creatinine level for kidney function and urine culture tests at
the end of first week, first month and at 3 months. Other conditions
such as PUV, VUR, and UPJ obstruction were diagnosed
on voiding cystourethrogram (VCUG) and DMSA.
Serum creatinine was used to find out the status of kidney function. At the postnatal age of 3 months, all babies with
either raised serum creatinine (more than 1.1 gm/dl) or those
who underwent surgery or who died were considered as having
adverse outcome. The antenatal ultrasound parameters
in those with adverse outcome were compared with normal
outcome.
Statistical Analysis
The data were entered into MS excel and analyzed using the SPSS version 17. Descriptive statistics in the form of mean and standard deviations or proportions were used to characterize the study sample. For quantitative data, difference between the means of the two groups were compared by t test (for normal distribution) or Mann Whitney test (nonnormal distribution). For qualitative data, Chi-square or Fischer’s exact test were used to observe difference between proportions for independent groups. p value of less than 0.05 was considered statistically significant. The antenatal factors of those with poor outcome were compared to good outcome using multivariate analysis. The sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) were calculated.
Total 50 cases with antenatal diagnosed bilateral hydronephrosis
were fully followed from 28 weeks of gestation till 3
months after birth and were therefore included in the study
group.
Most of the cases were in the age-group of 19–23 years
(48%) and were nulliparous (46%) (Table 1). Among
the antenatal ultrasound parameters, the mean AFI was 11.2 ± 3.1 cm at 28 weeks, but decreased to 7.8 ± 3.4 cm
at 32 weeks. The mean renal size of bilateral kidney was
more than 95th centile in 16% and 36% cases at 28 and
32 weeks, respectively. The mean renal pelvic diameter was 9.7 ± 4.4 mm at 28 weeks, but rose to 11.3 ± 4.7 mm at
32 weeks. Caliectasis was present in 4% and 8% cases at 28
and 32 weeks respectively. The bladder size was more than
4 cm in 34% subjects at 32 weeks, and ureteric dilatation was
observed in 6% of them. (Table 2).
The mean gestational age at delivery was
37.4 ± 1.7 weeks, and Cesarean section was performed in
5/50(10%) cases. All babies were alive at birth with the
mean Apgar score of 7, the male/female ratio was 2:1. The
details of postnatal outcome and management of babies are
given in Table 3.
The flowchart of the outcome of the cases is given in
Fig. 1. The bilateral pylectasis resolved in 8 cases at
32 weeks (16%), it was < 7 mm at postnatal one week in
further 6 (12%) cases, and it came back to normal at the end
of 3 months in 13 (26%) more cases. In 5 (10%) cases, it
persisted in one or both kidneys; however, the serum creatinine
was normal. Therefore, there was no adverse outcome
in total 32 (64%) cases.
Surgical intervention was required in 10 (20%) cases.
Cystoscopic fulguration was done in 5 (10%) cases of PUV,
and these cases were stable but had poor urinary stream and
were diagnosed as PUV on DMSA scan and VCUG. In 3
(6%) cases of severe, intractable VUR and deranged kidney
function, the ureteric reimplantation was performed within
the study period. Two cases having high-grade UPJ obstruction
underwent pyloplasty. In 5 cases, there was persistent
hydronephrosis with raised serum creatinine, but surgery
was not done as there was improvement in hydronephrosis
and serum creatinine levels on follow-up. Two cases with
PUV died.
When we correlated the antenatal ultrasound parameters
and the outcome, oligohydramnios had significant correlation
with electrolyte abnormality (p = 0.049), chances of
surgery (p = 0.012) and mortality (p = 0.041). Similarly, the
increased renal size and degree of renal pelvic dilatation
correlated significantly with the persistence of hydronephrosis
(p = 0.030) and the requirement of surgery (p = 0.048).
The presence of caliectasis was associated significantly with
the need for surgery and mortality. None of the ultrasound
parameters correlated significantly with raised serum creatinine
levels. The increased bladder size and thickness did not
correlate with adverse postnatal outcome (Table 4).
To assess how much each parameter contributed to the outcome,
the multivariate regression analysis along with ROC
curves were plotted. The sensitivity, specificity, negative predictive value, and positive predictive value of these parameters
are given in Table 5. Most of the parameters had better
sensitivity and specificity at 32 weeks than at 28 weeks. At
32-week gestation, the renal pylectasis between 10 and 15 mm
had highest sensitivity (88.9%), and the presence of caliectasis
had the highest specificity (90.6%) for predicting adverse
outcome. The presence of caliectasis was the best predictor of
adverse outcome with 66.7% sensitivity and 89.4% specificity.
This prospective study provides a good data on features on
ultrasound that would predict normal outcome in cases with
fetal renal pylectasis and therefore reduce the unnecessary anxiety of the couple. All babies were alive at birth, and
most of them recovered during the 3 months of follow-up;
surgery was required in one-fifth of them only. The parameters
such as amount of liquor, degree of pylectasis, and the
presence of caliectasis had better sensitivity and specificity
at 32 weeks than at 28 weeks. Renal caliectasis emerged as
the best marker for prediction of abnormal outcome.
The classification of ANH has been controversial due to
wide spectrum of causes and anomalies associated with it [6,
7, 8]. The anterior–posterior diameter (APD) measurement
system is believed to lack the descriptive detail of the part
of renal system involved [6]. The society of fetal urinary
tract (SFU) grading system is a five-point grading system
based on renal anatomic characteristics [7]. The urinary
tract dilatation (UTD) classification system was developed
to standardize the description of hydronephrosis across specialties
and provide unified recommendations for perinatal
evaluation. It is based on six categories in US findings such
as anterior–posterior renal pelvic diameter; calyceal dilation;
renal parenchymal thickness; renal parenchymal appearance;
bladder abnormalities; and ureteral abnormalities. The classification
system is stratified based on gestational age and
whether the ANH is detected prenatally or postnatally [8].
In the study by Chalmer et al. UTD was found to have better inter- rater reliability than SFU system [5]. In the present
study, we evaluated the kidney size, pylectasis, caliectasis,
bladder and ureteral abnormalities. Our classification was
measurement based, and hence, we omitted renal parenchymal
appearance component of UTD classification.
In the present study, after delivery, there was decrease in
pylectasis, bladder size, caliectasis along with regression of
serum creatinine levels towards normal with advancement
of age. Therefore, the natural progression after birth was
in favor of recovery in most of the cases. Similar findings
have been observed in previous studies also [1, 10, 11]. In
the present study, the resolution of ANH took place in 54%
of cases. Previous studies have shown that ANH resolves by
birth or during infancy in 41–88% patients [9, 10, 11, 12].
Surgery was performed in 10/50 (20%) cases in the present
study. This was akin to previous studies by Klener et al.
and Darwish et al., in which the surgical intervention was
required in 17.9% and 20.2% cases respectively [12, 13].
On multivariate analysis, the antenatal factors such as
oligohydramnios, kidney size, degree of pylectasis and
caliectasis were significant predictors of postnatal outcome
whereas the bladder size and the bladder thickness were
not. When all significant parameter was analyzed, it was
found that prediction by all markers were better at 32 weeks compared to 28 weeks. In the study by Klener et al., at APD
cutoff of 8.3 mm, the sensitivity and specificity for possibility
of surgery were 77.8% and 85.7% respectively [12]. In
the present study, at APD cutoff of 10 mm the sensitivity
was the highest (89%), whereas at the cutoff of 15 mm, the
specificity was the highest (87.5%). The parameters such as
oligohydramnios, increased kidney size and caliectasis had
NPV of over 80%, suggesting that if the above values were
below the cutoff, the chances of having good outcome was
more than 80%. In the study by Santos et al., it was similarly
concluded that caliectasis was an important marker of
adverse outcome after birth [14].
The major limitation of the study could be the limited
sample size and only 3 months of follow-up, but the strength
of the study was that it was a prospective study done from
antenatal to postnatal period and only bilateral fetal hydronephrosis
was studied, as prospective studies are required
to know the natural progression of the disease and bilateral
hydronephrosis is a different entity than unilateral affection.
The study provides data regarding the course and outcome
of bilateral hydronephrosis. Ultrasound features at
32 weeks was better in predicting the outcome; there was
resolution of hydronephrosis in half of the cases, and there
was adverse outcome in only one third of them. Renal caliectasis
emerged as the best marker for prediction of abnormal
outcome.
Funding There is no funding from any source for the study.
