Infected Kidney Stone in a Patient with Undiagnosed ADPKD: An Unusual Source of Postpartum Sepsis
Authors: Hartman Rachel , Colon Mercado Olga , Backstone Olivia , McConnell Nicole 
Published: July 2024

Introduction: Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common genetic diseases and has an incidence rate of 1 in 1,000-2,500. It is characterized by the development of cysts throughout the renal parenchyma and causes a progressive decline in renal function and eventually renal failure. In non-pregnant patients, common complications include hypertension, chronic pain from cysts, hematuria, urinary tract infection (UTI), and nephrolithiasis. Women who have chronic kidney disease (CKD) during pregnancy are at higher risk for both maternal and neonatal adverse outcomes including preeclampsia, worsening of renal function, preterm birth, and fetal growth restriction. Specific to ADPKD, some studies reported poor fetal outcomes and decline in maternal renal function with an increased risk of developing gestational hypertension, preeclampsia, and UTI. However, this research is not consistent and other studies suggest that there is only an increase in maternal complications if they have preexisting hypertension or elevated creatinine prior to pregnancy. This case presents a patient who was diagnosed with ADPKD as part of her workup for postpartum fever of unknown origin, and ultimately sepsis, from an infected kidney stone.

Case Report: A 29-year-old G2P0010 at 37 0/7 weeks was admitted for induction of labor for fetal growth restriction. She ruled in for preeclampsia with severe features during her intrapartum course. After her vaginal delivery, she remained in the hospital for blood pressure control. On PPD4, she ruled in for sepsis based on a fever of 102.2 F, hypotension, and tachycardia. Despite the absence of fundal tenderness or purulent lochia, patient was started on IV Gentamicin and Clindamycin empirically for endometritis. CT of the abdomen and pelvis showed severe polycystic kidney disease worse on the left and enlarged uterus with thickened endometrial echoes. Her urinalysis was positive for leukocyte esterase and white blood cells and blood cultures returned positive for gram negative rods; but still no source had been confirmed. Due to worsening sepsis, Internal Medicine (IM) was consulted, and antibiotics were changed to Cefepime and Flagyl. Nephrology was also consulted due to incidental finding of ADPKD and AKI. On PPD5, her leukocytosis worsened, and she continued to be febrile, so infectious disease (ID) was consulted. ID escalated the antibiotics to IV meropenem and suspected a gynecologic source of her sepsis. By PPD6, the blood cultures grew E. coli and by PPD7 her leukocytosis reached a peak of 30.5 103uL. She was transitioned to Cefazolin 1g IV q8hrs. On PPD 9, she was discharged home with 12 days of Ceftriaxone 2 g IV daily. On PPD 16, however, the patient was sent into the ED for evaluation after experiencing a fever of 101.3F in her obstetrician’s office and concern over retained products of conception due to a thickened endometrium noted on ultrasound. Despite undergoing dilation and curettage and continuing IV antibiotics, the fevers persisted. She began to report left sided flank pain. An MRI of the abdomen and pelvis was ordered and revealed moderate to severe left hydronephrosis due to an obstructing 6 mm stone at the left ureteropelvic junction. Urology was consulted and the patient had a cystoscopy, left retrograde pyelogram, ureteroscopy, and ureteral stent placement. During the procedure, purulence and sediment was noted in the left kidney, consistent with infected kidney stone. Urology suspected this was the source of her infection. She remained afebrile after the procedure and completed an additional week of Cefdinir. Upon discharge home, she followed up with urology and underwent an additional laser lithotripsy and basket extraction of stones.

Discussion: While UTI and nephrolithiasis are known complications of ADPKD during pregnancy, it is important to recognize early symptoms. It is estimated that women with ADPKD have a 14% increased risk of UTI. Untreated UTIs can lead to pyelonephritis, which is associated with preterm birth, low birth weight, and pregnancy loss. A less thought about complication of ADPKD, both in the pregnant and non-pregnant population, is nephrolithiasis. It is estimated that the incidence of nephrolithiasis ranges from 10 to 36% in patients with ADPKD. Nephrolithiasis can cause obstructions, worsen UTIs, and become infected, which is what occurred with the patient described above. It is thought that having large cysts, like our patient, places them at even higher risk for nephrolithiasis due to urinary statis. Our patient had multiple risk factors for nephrolithiasis. Ultimately, we had a favorable outcome, but if her infected kidney stone was diagnosed in a timelier fashion, she could have avoided worsening sepsis and a hospital readmission.

Conclusion: In patients with ADPKD and sepsis of unknown etiology, there needs to be a high suspicion for UTI, pyelonephritis, infected nephrolithiasis, and infected cysts, as all of these are associated with increased morbidity and mortality, especially during pregnancy and the post-partum period.