According to the present study, acute renal pain can be caused by hydroureteronephrosis, as observed in 84 cases (95.5%) in our study group. Among them, hydroureteronephrosis with secondary pyeloureteritis was observed in 65 cases (75%), renal stones were observed in 20 cases (23%), and ureteric obstruction by stones was observed in 10 cases (11.5%).
ureteric compression by uterine myoma in 1 case, a polycystic kidney disease with secondary renal stones in 1 case and acute pyelonephritis without renal back pressure changes in 3 cases.
Ultrasound can be used to assess the degree of hydronephrotic changes, to assess the size of the kidneys and the parenchymal echogenicity, to detect renal cysts or renal masses, to evaluate perinephric fat echogenicity in cases with suspected pyelonephritis and to assess the presence of perinephric collection.
It can follow the ureteric dilatation to the site of obstruction either with stones or ureteric compression by the gravid uterus (3, 5).
Evan et al and Butler et al reported that estimating the vascular renal resistive index was consistent with the current study. It can differentiate complete obstruction that shows an elevated estimated resistive index (RI) > 0.70, as observed in all our cases with obstructive uropathy (23% of cases),and incomplete obstructive dilation caused by ureteral compression that shows normal estimated RI (6, 7).
Patient with anatomical hydroureteronephrosis was frequently involved the right side as observed in 77% of our cases more than left side as observed in 11% of our cases, in agreement with studies reported by Schulman et al and Ciciu et al, due to ureteric compression by the gravid uterus and the narrow angle of the right ureter with respect to left ureter that showed a wide angle during crossing the iliac and ovarian vessels(2, 3).
The asymmetrical involvement of both the right and left upper urinary tracts makes it more likely to be caused by ureteric compression than a progesterone-related effect.
The ureteric compression is usually partial and incomplete, increasing as pregnancy progresses, and is more evident in the third trimester due to uterine enlargement (3).
In most cases, uterine compression caused by a gravid uterus resolves within a few weeks after delivery and can be managed medically without the need for surgical intervention (9).
The present study revealed that acute pyelitis was experienced by 75% of hydronephrosis cases. SAYLAM et al reported that in about 80% of pregnant, hydroureteronephrosis with secondary pyeloureteritis is a common issue that arises because of urinary stasis or cystitis ,leading to an ascending infection in the upper urinary tract. It can complicate surgical intervention with a ureteric stent and can also be found secondary to ureteral obstruction caused by stones (10).
In cases without ureteral stones, conservative management can be achieved through adequate hydration, analgesics, and antibiotic therapy, with excellent results (10, 11).
Patients who have renal stones are prone to passing stones that obstruct the ureters due to companion pyeloureteric dilation, which is associated with pregnancy and progesterone-related ureteral muscle laxity. Renal stones can pass down to the ureter spontaneously in about 70 to 80% of cases, among them about 50% of cases will expel the stones during the postpartum period (4, 6, 7)). However, some cases may not pass the stones and require further surgical intervention.
The current study revealed that 94% of cases with acute renal pain were successfully managed with medical and expectant treatment, while only 6% were managed with surgical intervention.
Predicting surgical intervention involves ureteric stones with a size > 7mm and moderate/marked pelvicalyceal dilation. Pain lasting more than 4 days and fever. Small stones less than 4mm can be treated medically and expectantly when the spontaneous passage rate reaches 50% or more (4).
An associated secondary pyelitis can be treated with antibiotic therapy.
Pregnant females with lower urinary tract irritative symptoms should be subjected to perform urine analysis to detect pyuria and abdominal ultrasound to rule out lower ureteric stones and to assess for possible cystitis.
To prevent secondary upper urinary tract infections, it is important to manage cystitis adequately.
It's crucial for patients with acute pyelonephritis to receive antibiotic therapy that is both adequate and early to prevent complications like renal abscesses, perinephric collections that need to be drained, and to prevent systemic sepsis.
Patients with a known history of polycystic kidney disease are more liable to develop renal stones that may pass to obstruct the ureter, therefore should be adequately followed during their pregnancy.