CASE REPORT | https://doi.org/10.5005/jp-journals-10006-1977 |
Solitary Kidney: Harbinger of Adverse Pregnancy Outcomes
1,2Department of Obstetrics and Gynaecology, King Khalid Hospital, Al-Kharj, Riyadh, Saudi Arabia
Corresponding Author: Surya Malik, Department of Obstetrics and Gynaecology, King Khalid Hospital, Al-Kharj, Riyadh, Saudi Arabia, Phone: +966572946099, e-mail: surya85.sm@gmail.com
How to cite this article: Malik S, Sheikh SA. Solitary Kidney: Harbinger of Adverse Pregnancy Outcomes. J South Asian Feder Obst Gynae 2021;13(6):438–440.
Source of support: Nil
Conflict of interest: None
ABSTRACT
Aim and objective: The aim of the article was to throw light on the potential risks associated with solitary kidney, especially in relation to maternal and fetal outcomes.
Background: Solitary kidney can be caused by three main reasons: Being born with a single kidney, losing one because of a disease, or an injury, or donating a kidney to a family member or friend who has lost one of their own.
Case description: A 38-year-old G7P4A2 patient with a 36.2-week period of gestation was admitted with antepartum hemorrhage. The patient was thoroughly examined and necessary investigations were done. On pelvic examination, there was mild spotting present. On routine investigations, she was found to be severely anemic and chronic kidney disease stage 5. According to the nephrology team’s advice, an ultrasound of kidney, ureter, and urinary bladder (KUB) was done. It was detected as a case of congenital unilateral agenesis of the kidney. She had complaints of intermittent mild loin pain and dysuria. The patient was immediately transfused four units of packed cells for correction of anemia and was given steroid cover for fetal lung maturity. The patient was taken for hemodialysis in view of end-stage renal disease. After one session of hemodialysis, the patient was taken up for Cesarean section in view of placenta previa with a deranged renal profile. A single alive female baby weighing 2200 g was extracted with an Apgar score of 8, 9. The intraoperative period was uneventful. The patient was transferred to the intensive care unit for postoperative care.
Conclusion: Solitary kidney from renal agenesis is a significant and independent risk factor for adverse maternal and fetal outcomes.
Clinical significance: As unilateral renal agenesis (URA) is associated with potential risks, hence preconception counseling, close monitoring throughout their antenatal and postpartum period, and a multidisciplinary approach are required to have good pregnancy outcomes in these patients.
Keywords: Pregnancy, Solitary kidney, Unilateral renal agenesis
BACKGROUND
Solitary kidney can be caused by three reasons: being born with a single kidney, losing one because of a disease or an injury, and donating a kidney to a family member or a friend who has lost one of their own.1,2 Unilateral renal agenesis (URA) is defined as the one-sided congenital absence of renal tissue resulting from the failure of embryonic kidney formation.3,4 URA should be discriminated from abnormal or incomplete renal development leading to the nonfunctioning kidney as can be identified in a multicystic dysplastic kidney or renal aplasia.5 The general incidence of URA is approximately 1 in 2000 and was more often identified in males and more often located on the left side.6 There is increasing evidence suggesting that either inherited or acquired nephron loss is associated with the increased risk of proteinuria and renal insufficiency. Experimental models of renal ablation have demonstrated the important role of hyperfiltration at the onset of renal impairment.7,8 Evidence shows that renal mass (i.e., the quantity of nephrons) is a major risk factor for the development of hypertension and glomerular injury. Hypertension, proteinuria, or renal failure was present in approximately two-thirds of patients with renal agenesis/dysplasia. Those with hypertension and proteinuria had a higher risk of progression to renal insufficiency.9 Hypertension, microalbuminuria, and renal functional impairment were identified in 16, 21, and 10% of URA patients, respectively.6 Hyperuricemia and increased fractional urate excretion have recently been reported in patients with solitary kidney and it is thought that these factors might be harmful to the structure and function of the remaining kidney.10 Sanna-Cherchi et al.11 demonstrated that adults with URA show a high frequency of end-stage renal disease at 30 years of age, indicating that URA should not be considered a harmless malformation.
CASE DESCRIPTION
A 38-year-old female G7P4A2 patient with a 36.2-week period of gestation was admitted with antepartum hemorrhage. The patient was thoroughly examined and necessary investigations are done: BP—110/70 mm Hg, PR—76/minute, pallor++; per abdomen—soft, nontender, fundal height corresponding to 34 weeks; and fetal heart rate—146/minute. On pelvic examination, there was a mild per-vaginal (PV) spotting of blood present. On routine investigations, she was found to be severely anemic with hemoglobin of 6.5 g%, urea—18 mmol/L, creatinine—620.17 µmol/L, uric acid—487 µmol/L, Na+—128 mmol/L, K+—5 mmol/L, Cl—110 mmol/L, RBS—3.5 mmol/L, and urine protein++. The patient was stabilized and an urgent abdominal ultrasound (USG) was done. On USG, she was diagnosed to be a case of placenta previa type II anterior. Nephrology referral was done and according to their advice ultrasound of kidney, ureter, and urinary bladder (KUB) was done. On ultrasound, only the right kidney was present with increased parenchymal echogenicity and moderate corticomedullary differentiation, a mild degree of pelvicalyceal dilatation, and bulky right suprarenal gland. There was no history of nephrectomy; hence, it was a case of congenital unilateral agenesis of the kidney. She had intermittent mild loin pain and dysuria suggestive of urinary tract infection. The patient had no history of a previous deranged renal profile. The patient’s previous pregnancies were uneventful except she had a history of pregnancy-induced hypertension in previous pregnancy for which she took treatment. She was not on any medication at present except multivitamins. The patient was immediately transfused four units of packed cells for the correction of anemia and was given steroid cover for fetal pulmonary maturity. The patient’s consent was taken for hemodialysis in view of end-stage renal disease. After one session of hemodialysis, the patient was taken up for the Cesarean section in view of placenta previa with deranged renal profile after the correction of anemia. A single alive female baby weighing 2200 g was extracted with an Apgar score (8/1 and 9/5 minutes). The intraoperative period was uneventful. The patient was transferred to the intensive care unit for postoperative care. On day 3 of the Cesarean section due to the deteriorating renal profile, hemodialysis was planned by a nephrologist; hence, she was referred to the nephrology department for further treatment and follow-up.
DISCUSSION
Kendrick et al.12 did a cohort study regarding the association of URA with adverse outcomes in pregnancy. In the cohort selected by authors, none of the women had diabetes mellitus or proteinuria at baseline and all were having a normal renal function. The primary outcomes of the study were adverse pregnancy outcomes, including preterm delivery, delivery via Cesarean section, preeclampsia/eclampsia, and length of stay at the hospital. Adverse neonatal endpoints were considered as secondary outcomes and included low birth weight babies (<2500 g) and infant death/transfer to an acute inpatient facility. It was reported that women with URA had a higher risk of preterm delivery than women with two kidneys (20.5 vs 8.5%, p <0.001). URA makes women more prone to have delivery via Cesarean section (33.5 vs 19.6%), preeclampsia/eclampsia (7 vs 3%), and a length of hospital stay of more than 3 days (18.5 vs 11.4%), as compared to women having two kidneys. In terms of neonatal outcomes, these women had a higher prevalence of low birth weight babies (16.5 vs 5.6%). In another study of adults with renal agenesis with normal kidney function, absence of proteinuria, and no structural abnormalities of the remaining kidney at the time of diagnosis, 47% developed hypertension, 13% had a decrease in glomerular filtration rate, and 4% died of kidney failure.13 These data suggest that URA is associated with subclinical defects that result in adverse renal outcomes as well as adverse pregnancy outcomes. Piccoli et al.14 also reported an increased risk of preterm delivery in mothers with single kidney even if considering only stage 1 chronic kidney disease. The chances of small for gestational age baby are also higher as compared to low-risk cohorts (p <0.001). Shekhtman and Petrova15 also reported a decline in renal function, pyelonephritis of the solitary kidney occurred more frequently in women with solitary kidney (77.8%). Obstetric complications also arose more frequently in these women with two kidneys: gestosis (toxemia of pregnancy)—28% and premature delivery—25%. Steele et al.16 also reported an increased risk of urinary tract infection (50%), preeclampsia, gestational hypertension, and gestational proteinuria (35%). Hence, patients with solitary kidney need to be counseled regarding risks of developing pyelonephritis, preeclampsia, and its associated complications during pregnancy.
CONCLUSION
In conclusion, solitary kidney from renal agenesis is a significant and independent risk factor for adverse maternal and fetal outcomes. Hence, preconception counseling; education on how to protect their single kidney; preeclampsia prophylaxis with low-dose aspirin; close monitoring for urinary tract infection, hypertension, and proteinuria with lower thresholds for pharmacological treatment; and multidisciplinary care are the strategies that can be inculcated to improve maternal and fetal outcomes and to delay the onset of chronic kidney disease.
CLINICAL SIGNIFICANCE
As women with URA are at increased risk of developing hypertension, microalbuminuria, or chronic kidney disease, a model for coordinated prepregnancy care of women with a single kidney, vigilant monitoring, and prompt treatment of complications is a prerequisite for optimizing outcomes. It emphasizes the unique opportunity we have during pregnancy to educate and engage women and clinicians about the importance of robust care of the remaining kidney and lifelong annual surveillance thereafter to ensure optimal longevity of remaining renal tissue and general health.
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