Catastrophic complications of urolithiasis in pregnancy

Abstract

Urolithiasis is the most common non-obstetric complication in pregnancy and has the potential to cause grave consequences resulting in pregnancy loss. We present two such cases. First, a 24-year-old woman, 5 weeks pregnant with a history of urolithiasis presented with right flank pain and fever. She was found to have a right perinephric collection and during the course of her treatment suffered an abortion. The second case was a 25-year-old woman who presented in septic shock. She underwent emergency lower segment caesarean section elsewhere 10 days ago for intrauterine death at 38 weeks of gestation. On evaluation, she was found to have bilateral stone disease with a left subcapsular haematoma. Both the cases were managed conservatively and are planned for definitive management. Thus, women of childbearing age with diagnosed urolithiasis should get themselves evaluated and be free of stone disease before planning a family to prevent increased obstetric complications during pregnancy.

Background

Maternal urolithiasis is the most common non-obstetric complication during pregnancy. The prevalence of renal stone disease in pregnancy is reported to be around 1 in 200 to 1 in 1500 pregnancies.¹ The diagnosis and management of stone disease in a gravid patient is challenging, compounded by the physiological changes that occur during pregnancy as well as the potential harm to the developing fetus. The most critical point to remember is that every decision taken regarding the appropriate diagnosis and management of urolithiasis in pregnancies affects two lives, that of the mother and the fetus. Thus, it requires multidisciplinary team management comprising primarily of the obstetrician and the urologist. From an obstetrical point of view, the main aim in such situations is to maintain a proper course of pregnancy with good maternal and fetal outcomes, and from a urological point of view, the main aim is to save the kidney unit, whose functionality may be jeopardised secondary to obstruction and uropathy.² More often than not, both these aims are difficult to achieve, requiring a careful assessment of benefits and risks both to the mother and the developing fetus.

The challenges faced in such situations are manifold. First, deciding the appropriate modality for diagnosis to minimise the radiation exposure to the fetus. Second, deciding the appropriate management strategy and timing of stone clearance and whether any temporary diversion measures are required. These decisions are complicated by the inherent complications that urolithiasis and acute renal colic carry to both the mother and the fetus, such as preterm labour, preterm premature rupture of membranes, recurrent loss of pregnancy and pre-eclampsia.³ The whole situation is further compounded by the complications that might be associated with the stone disease itself such as hydronephrosis, infected hydronephrosis, pyonephrosis, renal abscess, perinephric urinoma and perinephric abscess. In the present report of two cases, we intend to highlight two such case scenarios associated with obstructive and infectious complications of stone disease, which led to abortion in the first trimester and intrauterine death near term in the two cases, respectively. A review of pathogenesis, diagnostic modalities and management strategies and decision-making are detailed herewith.

Case presentation

Case 1

A 24-year-old woman presented to the emergency room with reports of right flank pain, vomiting and fever for the past 3 weeks. The flank pain was episodic with moderate intensity, associated with intermittent vomiting. She also had history of intermittent fever spikes associated with chills. History of passage of stones in the urine was present several months ago and also 5 days ago. She was married for 3 years with a 1½-year-old daughter. She had one previous lower segment caesarean section (LSCS) done for non-progress of labour. A thorough history revealed that she had missed her menstrual cycle (last menstrual period was 6 weeks ago) and consequently a urinary pregnancy test was done, which was positive. On examination, she was anaemic, febrile to touch and right flank tenderness was present.

An ultrasonography scan showed a dilated right pelvicalyceal system with internal echoes and debris. Also, a rent in the lower pole of the right kidney was noted with a 13×8 cm perinephric collection. The ureter could not be visualised due to excessive bowel gas. A gestational sac was noted in the uterus with fetal cardiac activity present. Blood work-up revealed a haemoglobin of 99 g/L and leucocytosis (18×10⁹/L). Serum urea and creatinine were within normal limits. With a diagnosis of right infected hydronephrosis and a perinephric collection, the patient underwent placement of a percutaneous nephrostomy (PCN) as well as a percutaneous catheter drainage (PCD) of the perinephric collection. PCN initially drained turbid urine, which was later replaced by clear urine (200 mL/day) and the PCD output was 200 mL frank pus, which dried up in the next 48 hours. The patient was conservatively managed with cephalosporins as per culture sensitivity of the pus (positive for Escherichia coli). On day 2 of her admission, she had lower abdominal pain and spotting per vaginum. A check ultrasound revealed a spontaneous abortion with no gestational sac in the uterus. There was minimal hydronephrosis of the right kidney with PCN in situ and only a minimal perinephric collection with PCD in situ.

Three days after the spontaneous abortion of the fetus, a CT urography scan was performed, which revealed a shrunken right kidney with multiple parenchymal abscesses communicating with a peripheric collection suggestive of ruptured right pyonephrosis (figure 1). The upper pole of the kidney was enhancing with excretion of contrast. No calculus was noted (recently passed out stone). The patient was discharged with PCN in situ.

Figure 1.

Contrast-enhanced CT scan in case 1 showing the shrunken right kidney with perinephric collection with percutaneous nephrostomy and percutaneous drain in situ (arrows).

Case 2

A 25-year-old woman presented to the emergency room 10 days after an emergency LSCS performed elsewhere. She had a history of bilateral flank pain since the seventh month of pregnancy with occasional vomiting episodes. At 38 weeks of gestation, an emergent LSCS was performed in view of fetal bradycardia, which had resulted in intrauterine death of the fetus. Post LSCS, the patient developed decreased urine output and febrile episodes associated with vomiting for which she was referred to our centre. On arrival, the patient was febrile, tachycardic and hypotensive (temperature 100.6°F, blood pressure 90/60 mm Hg and pulse rate 116/min). She was resuscitated with intravenous fluids and broad-spectrum antibiotics. Urine output was 20–30 mL/hour initially, which gradually rose to 50 mL/hour after successful resuscitation. On examination, abdomen was soft with a healthy LSCS wound. Blood investigations revealed a haemoglobin of 83 g/L, total leucocyte count 40.8×10⁹/L, platelet count 20 000/mm³, blood urea 267 mg/dL and a serum creatinine of 5.96 mg/dL. She also had a plain CT kidney, ureter and bladder performed elsewhere 7 days after LSCS which showed an obstructive proximal left ureteric calculus 20 mm in size causing moderate upstream left hydroureteronephrosis and multiple non-obstructive stones in the right kidney.

In the emergency room, ultrasonography revealed moderate hydronephrosis of the left kidney secondary to an obstructive calculus in the upper ureter with a large perinephric collection covering the kidneys on all the sides. The patient underwent three sessions of haemodialysis in view of oliguria due to acute kidney injury. Subsequently, she also underwent a PCN. The puerperal sepsis with the resultant acute kidney injury and thrombocytopenia was treated conservatively with intravenous meropenem in a renal modified dose. After 7 days of conservative management, the leucocyte and the platelet count normalised. Also, the acute kidney injury resolved with a serum creatinine of 1.05 mg/dL and a 24-hour urine output >2.5 L.

After stabilisation of the patient, a CT urography was done at our institute. It showed a large 22 mm left midureteric calculus causing moderate hydroureteronephrosis with a 12×8 cm perinephric haematoma (HU-65) causing compression of the left kidney. The right kidney showed multiple renal stones, largest of size 31 mm at the lower pole with mild hydroureteronephrosis. No active contrast extravasation was seen. PCN was seen in situ (figure 2). Uterus was postpartum in size with a 2.8 cm rent on its anterior wall at the lower uterine segment with multiple small collections anterior to uterus, rectouterine pouch and left paracolic gutter. A PCD tube was inserted in the subcapsular renal haematoma which drained 200 mL of collected blood. The patient was managed conservatively with aspiration of intra-abdominal collections. The drain dried up within 4 days and was removed. Check ultrasound showed no intra-abdominal collections. The patient was discharged with left PCN in situ.

Figure 2.

Contrast-enhanced CT scan in case 2 showing the right kidney stone (red arrow), left midureteric stone (blue arrow) and the left subcapsular haematoma (star).

Outcome and follow-up

Case 1 had an abortion at 6 weeks of pregnancy and was discharged with PCN in situ. On telephonic follow-up after 10 days, she is doing well with nephrostomy in situ draining 200 mL/day. Blood biochemistry is within normal limits. She is planned for a nuclear medicine scan after 4 weeks to assess the functionality and drainage of the right kidney unit. Further management will be decided based on findings of the diuretic renography.

Case 2 was diagnosed with puerperal sepsis following a LSCS for Intra uterine death (IUD) at 38 weeks of pregnancy with bilateral urolithiasis. She was managed conservatively for the same. Her condition improved and she was discharged with a left PCN. After the 4-week follow-up, the patient is doing well with nephrostomy in situ draining over 1 L a day and a check ultrasound showing resolution of the perinephric haematoma. Serum urea and creatinine are within normal limits. She is planned for a left ureteroscopic lithotripsy and a right percutaneous nephrolithotomy after 4 weeks.

Discussion

The incidence of stone disease in pregnant population is no different than that of general population; however, multiparous women tend to be affected more by urolithiasis than primiparous women.⁴ Acute renal colic secondary to stones is the leading non-obstetric cause of hospitalisation in the gravid patient, occurring most commonly in the second or third trimester.⁵ The pain caused by stones and the associated urinary tract infection and obstruction increase the risk for maternal and fetal complications, such as preterm labour, preterm premature rupture of membranes, recurrent loss of pregnancy, pre-eclampsia and placenta previa.⁶ Despite this substantially increased morbidity, the association of perinatal outcomes measured in terms of birth weight, Apgar score and perinatal mortality is not clinically significant.⁷ The aetiology, diagnosis and management of stone disease in pregnancy is detailed as follows.

Aetiology

The anatomical and physiological changes in the urinary tract that occur during pregnancy and the resultant urinary tract obstruction and stasis predispose the gravid patient to urolithiasis. The predominant factors, which are responsible for a change in the urinary milieu, include both mechanical and humoral factors. Dilatation of the pelvicalyceal system is commonly seen during pregnancy with a right side predominance seen in 90% of the pregnant women by the third trimester.⁸ The reasons include the mechanical compression of the gravid uterus as well as smooth muscle relaxation caused by progesterone, which results in decreased peristalsis and stasis. The right side is more predominantly affected due to the dextroversion of the uterus, crossing of the right ureter near the pelvic brim and protection of the left ureter by the sigmoid mesocolon.⁹ Other physiological changes promoting stone formation include an increased renal blood flow and glomerular filtration rate with increased urinary excretion of calcium, sodium and uric acid, leading to hypercalciuria and hyperuricosuria.^{10 11} Physiological changes in the urinary tract during pregnancy are summarised in table 1.

Table 1.

Physiological changes during pregnancy

Factors promoting stone formation	Factors inhibiting stone formation
1. Mechanical compression of ureters due to gravid uterus	1. Hypercitraturia due to increased glomerular filtration rate
2. Urinary stasis due to smooth muscle relaxation due to progesterone	2. Increased excretion of stone inhibitors like magnesium, uromodulin, nephrocalcin and glycosaminoglycans
3. Hypercalciuria due to increased excretion of calcium and increased vitamin D levels
4. Increased excretion of stone-forming agents like uric acid, calcium, sodium and oxalate
5. Increased urinary pH

Diagnosis

Urolithiasis usually presents as flank pain, which may be colicky in nature, if it is obstructive and might be associated with microhaematuria or macrohaematuria. However, when the patient presents with acute abdomen during the latter half of pregnancy, the list of differential diagnosis includes appendicitis, cholecystitis, pyelonephritis, abruption and preeclampsia with hepatic involvement due to relative change in position of various abdominal organs caused by the expanding gravid uterus. Blood chemistries, counts and urinary microscopic examination are important in the diagnosis of urinary tract stones.¹²

Imaging is the mainstay of diagnosis; however, due considerations are to be given to limit the amount of radiation exposure to the developing fetus. According to the American College of Gynecology (ACOG) guidelines, ultrasound and MRI are the imaging modalities of choice during pregnancy as they are associated with no radiation exposure and fetal risk. Also, the guidelines suggest that if ultrasound and MRI do not answer the clinical question, radiography, CT scan or nuclear medicine imaging techniques should not be withheld from a pregnant patient as the dose is usually lower than that associated with fetal harm.¹³ The current American Urological Association guidelines also recommend that if radiation exposure is necessary for the diagnostic or therapeutic purposes, in consultation with the obstetrician, the radiologist must take care that the total radiation exposure does not exceed the ACOG recommendation of 50 mGy.¹⁴ The various imaging modalities, their benefits and risks are summarised in table 2 and the amount of radiation exposure is outlined in table 3.

Table 2.

Various modalities used in the diagnosis of urolithiasis in pregnant patients

S.No.	Imaging modality	Remarks
1.	Ultrasonography	First-line imaging modality in pregnant patients with urolithiasis No radiation exposure Operator-dependent, difficult to distinguish physiological from pathological hydronephrosis, ureteral calculi may be obscured and missed Sensitivities range from 29% to 69%18
2.	Colour Doppler ultrasonography	a. Ureteral jets. Detection of ureteral jets rules out complete obstruction. However, absence of jets may be due to compression of the ureter by the uterus and are thus unpredictable b. RI of intrarenal blood flow. RI threshold of 0.7 (sensitivity 45% and specificity 91%) and change in RI >0.06 (sensitivity 95% and specificity 100%) are strong predictors of ureteral obstruction on the ipsilateral side, if done within 6–48 hours of presentation12
3.	Transvaginal ultrasound	Improves stone detection rates by visualising the distal ureter Ureteral jets are also visualised
4.	MRI	No use of ionising radiation or contrast medium Does not visualise calcium stones, observed as filling defects in the high signal intensity of urine Accurately differentiates physiological from pathological dilatations of the ureter Half-Fourier acquisition single-shot turbo spin-echo protocol improves the performance of MRI in detecting stones19
5.	Intravenous urography	Infrequently employed Limited intravenous urography with single shot, two or three films Limiting radiation exposure by fetal shielding, collimation and low-dose spot films20
6.	CT scan	Unenhanced CT usually avoided due to high radiation exposure Low-dose CT has emerged as high utility and low-risk technique (fetal radiation dose 4 mGy versus 25 mGy) Ultra-low-dose CT may provide even greater utility Dose reduction is performed by limiting the scan coverage area and reducing the tube voltage21

CT, contrast tomography; RI, resistive index.

Table 3.

Radiation dose associated with various imaging modalities

S.No.	Imaging technique	Effective dose (mSv)
1.	Ultrasonography	0
2.	Plain X-ray kidney, ureter and bladder	0.7
3.	Intravenous urography	3.0
4.	Non-contrast abdomen and pelvis	10.0
5.	Without and with contrast, abdomen and pelvis (two phase)	15.0
6.	Without and with contrast, abdomen and pelvis (three phase)	20.0
7.	Non-contrast CT, abdomen and pelvis (low-dose protocol)	3.0
8.	Non-contrast CT, abdomen and pelvis (ultra-low-dose protocol)	<1.0
9.	MRI	0

Management

The management of urolithiasis during pregnancy is a challenging task as it involves saving the pregnancy as well as the affected kidney unit. The rates of spontaneous expulsion of stones are high, thus expectant management with hydration and analgesics should be considered as the first-line therapy in this patient population as well.¹⁵ Good hydration increases the urine output and may help facilitate stone passage. The choice of analgesics in pregnancy is opioids, as non-steroidal anti-inflammatory drugs have the potential to cause oligohydramnios and premature closure of ductus arteriosus.¹⁶ However, in the presence of any complicating factor (figure 3), intervention might be required. The timing and choice of intervention depends on several factors, namely the period of gestation, symptomatology and the presence of associated complications of stone disease. We propose a management guideline of urolithiasis in pregnancy after a thorough review of literature as outlined in figure 3. Intervention in pregnancy could be in the form of temporising measures such as PCN or indwelling ureteral stents as well as definitive treatment of stone in the form of ureteroscopic or percutaneous methods.¹⁷

Figure 3.

Proposed management guideline of urolithiasis in pregnancy. MET, medical expulsion therapy; MRU, magnetic resonance urography.

Until recently, temporising measures were preferred over definitive treatments due to the ease of performing the procedure, quick relief of obstruction and minimum exposure to radiation. However, these stents and tubes are fraught with complications like encrustations due to hyperuricosuria and hypercalciuria, leading to recurrence of obstruction and frequent exchanges. Thus, the trend is slowly shifting towards definitive procedures.¹⁷ Ureteroscopic inspection and retrieval of stone is considered the procedure of choice whenever indicated as it can be performed under spinal anaesthesia or sedation, has high success rates and can be performed without ionising radiations. Extracorporeal shockwave lithotripsy is contraindicated in pregnancy due to fetal damage and death reported in experimental studies. Percutaneous nephrolithotomy requires a prone position, general anaesthesia as well as radiation exposure and hence is avoided during pregnancy.¹⁷

Both our index cases presented with complications due to stone disease. In case 1, there was a perinephric collection, which was managed with pigtail drainage. It was almost certain that the pregnancy loss occurred due to urolithiasis and its associated complications as cardiac activity was present during admission and spontaneous abortion occurred during the hospital stay. As with case 2 as well, the patient had a history of lithuria with documented stone disease during her pregnancy and had no other symptoms or complications of pregnancy to which the intrauterine death could be attributed to. Thus, in this case as well the pregnancy loss was a result of sepsis due to stone disease. Both the cases were managed conservatively and the mothers were the utmost priority in management. In retrospect, it is the authors point of view that complications could have been prevented if pregnancies were planned after early diagnosis and treatment of the stone disease. Management of these complicated cases is thus challenging, with two lives at risk and limited diagnostics to choose from.

Patient’s perspective.

Patient 1: It was a traumatic experience to lose my child so early in the pregnancy. I had known about my stone disease and had neglected it. I urge all the other women to not ignore any pain and get yourself tested and treated. This loss is difficult to bear. I thank my doctors for standing by me in these difficult times.

Patient 2: I would like to express my deep gratitude towards the treating team to have saved my life. This experience was very tough and had a deep effect on me and my family. Stone disease should be taken seriously, otherwise it can wreak havoc as it did in my case. I am lucky to have survived this.

Learning points.

• Women of childbearing age with diagnosed urolithiasis as well as those with a high index of suspicion should get themselves evaluated and be free of stone disease before planning a family to prevent increased obstetric complications during pregnancy, as urolithiasis has the potential to cause catastrophic events, such as pregnancy loss, which may be a source of severe mental trauma to the mother and the family.

• When diagnosed during pregnancy, urolithiasis requires an increased level of care and treatment to prevent untoward maternal and fetal complications.

• The diagnosis and management of stone disease in this patient group is challenging as many of the procedures involved have an inherent risk to the fetus.

• Ultrasound remains the first-line diagnostic modality of choice for diagnosis. Management includes temporising diversion or definitive stone removal depending on several clinical factors.

• These women thus require a multidisciplinary team effort, including obstetricians, urologists, anaesthetists, radiologists and neonatologists, for a safe maternal and fetal outcome as well as optimum preservation of the kidney unit.