Kidney Imaging and Biopsy in Pregnancy
2020; Elsevier BV; Volume: 27; Issue: 6 Linguagem: Inglês
10.1053/j.ackd.2020.05.012
ISSN1548-5609
Autores Tópico(s)Pregnancy and preeclampsia studies
ResumoPhysiologic glomerular, tubular, and structural changes related to pregnancy may complicate the detection of underlying kidney disease in pregnant patients. Imaging studies may provide important clinical information to assist in the diagnosis and treatment of kidney disease during pregnancy. Furthermore, in select patients who develop new or worsening kidney disease in pregnancy, kidney biopsy may be essential to ensure the accuracy of diagnosis and guide treatment choices. This review article will discuss the risks and benefits of various modalities used to image the kidneys and urinary tract during pregnancy to aid in the judicious selection of appropriate imaging studies that are likely to maximize clinical benefit while minimizing fetal risk. It will also highlight the potential benefits and harms associated with antepartum kidney biopsy and will offer strategies for identifying patients who are most likely to benefit from kidney biopsy during pregnancy. Physiologic glomerular, tubular, and structural changes related to pregnancy may complicate the detection of underlying kidney disease in pregnant patients. Imaging studies may provide important clinical information to assist in the diagnosis and treatment of kidney disease during pregnancy. Furthermore, in select patients who develop new or worsening kidney disease in pregnancy, kidney biopsy may be essential to ensure the accuracy of diagnosis and guide treatment choices. This review article will discuss the risks and benefits of various modalities used to image the kidneys and urinary tract during pregnancy to aid in the judicious selection of appropriate imaging studies that are likely to maximize clinical benefit while minimizing fetal risk. It will also highlight the potential benefits and harms associated with antepartum kidney biopsy and will offer strategies for identifying patients who are most likely to benefit from kidney biopsy during pregnancy. Clinical Summary•Pregnancy causes multiple changes in kidney structure and function, potentially complicating the detection of kidney disease.•Kidney imaging or biopsy may be necessary for accurate diagnosis and/or management in pregnant patients.•Ultrasound is the kidney imaging modality of choice during pregnancy.•Kidney biopsy during pregnancy should be considered only in cases where less-invasive methods of diagnosis have been exhausted and/or biopsy will change management.•If deemed medically necessary, kidney biopsy should be performed before 30-week gestation. •Pregnancy causes multiple changes in kidney structure and function, potentially complicating the detection of kidney disease.•Kidney imaging or biopsy may be necessary for accurate diagnosis and/or management in pregnant patients.•Ultrasound is the kidney imaging modality of choice during pregnancy.•Kidney biopsy during pregnancy should be considered only in cases where less-invasive methods of diagnosis have been exhausted and/or biopsy will change management.•If deemed medically necessary, kidney biopsy should be performed before 30-week gestation. Diagnosing kidney disease in pregnancy can be challenging given the numerous physiologic changes in kidney function that occur with normal gestation. Glomerular hyperfiltration results in a lower serum creatinine concentration, such that an apparently normal creatinine in a pregnant patient may represent underlying kidney dysfunction.1Williams D. Davison J. Chronic kidney disease in pregnancy.BMJ. 2008; 336: 211-215Crossref PubMed Scopus (207) Google Scholar,2Maynard S.E. Thadhani R. Pregnancy and the kidney.J Am Soc Nephrol. 2009; 20: 14-22Crossref PubMed Scopus (104) Google Scholar The Modification of Diet in Renal Disease and Chronic Kidney Disease-Epidemiology Collaborative equations are widely used to correct for patient factors (age, sex, and race) that affect the interpretation of serum creatinine levels.3Levey A.S. Inker L.A. Coresh J. 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The role of imaging in the diagnosis and management of renal stone disease in pregnancy.Clin Radiol. 2015; 70: 1462-1471Abstract Full Text Full Text PDF Scopus (16) Google Scholar Urinary retention and stasis as a result of these morphologic urinary tract changes places pregnant women at higher risk of developing urinary tract infections.15Kalinderi K. Delkos D. Kalinderis M. Athanasiadis A. Kalogiannidis I. Urinary tract infection during pregnancy: current concepts on a common multifaceted problem.J Obstet Gynaecol. 2018; 38: 448-453Crossref PubMed Scopus (65) Google Scholar Moreover, symptomatic nephrolithiasis is not uncommon in pregnant women, with incidence estimates ranging from 1 in every 200 to 1 in every 1500 pregnancies.16Masselli G. Derme M. Bernieri M.G. et al.Stone disease in pregnancy: imaging-guided therapy.Insights Imaging. 2014; 5: 691-696Crossref Scopus (17) Google Scholar In particular, stone disease during pregnancy has been associated with a number of poor outcomes, including preeclampsia and preterm labor and delivery,12Masselli G. Weston M. Spencer J. The role of imaging in the diagnosis and management of renal stone disease in pregnancy.Clin Radiol. 2015; 70: 1462-1471Abstract Full Text Full Text PDF Scopus (16) Google Scholar,16Masselli G. Derme M. Bernieri M.G. et al.Stone disease in pregnancy: imaging-guided therapy.Insights Imaging. 2014; 5: 691-696Crossref Scopus (17) Google Scholar and imaging may serve an important role in determining the need for more aggressive urological intervention. Ultrasound is frequently used for anatomical kidney evaluation in nonpregnant patients. Sonography has a number of advantages in the diagnosis of kidney and urinary tract abnormalities. It is widely available in most hospitals and clinics, portable, and relatively easy to perform.17O'Neill W.C. Renal relevant radiology: use of ultrasound in kidney disease and nephrology procedures.Clin J Am Soc Nephrol. 2014; 9: 373-381Crossref PubMed Scopus (50) Google Scholar Ultrasound is the preferred imaging modality for use during pregnancy and should always be used for the initial evaluation of anatomic abnormalities in pregnant patients.16Masselli G. Derme M. Bernieri M.G. et al.Stone disease in pregnancy: imaging-guided therapy.Insights Imaging. 2014; 5: 691-696Crossref Scopus (17) Google Scholar,18Jaffe T.A. Miller C.M. Merkle E.M. Practice patterns in imaging of the pregnant patient with abdominal pain: a survey of academic centers.AJR Am J Roentgenol. 2007; 189: 1128-1134Crossref PubMed Scopus (54) Google Scholar, 19Wieseler K.M. Bhargava P. Kanal K.M. Vaidya S. Stewart B.K. Dighe M.K. 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Bhargava P. Kanal K.M. Vaidya S. Stewart B.K. Dighe M.K. Imaging in pregnant patients: examination appropriateness.Radiographics. 2010; 30 (discussion 30-33): 1215-1229Crossref PubMed Scopus (113) Google Scholar,21Patel S.J. Reede D.L. Katz D.S. Subramaniam R. Amorosa J.K. Imaging the pregnant patient for nonobstetric conditions: algorithms and radiation dose considerations.Radiographics. 2007; 27: 1705-1722Crossref PubMed Scopus (293) Google Scholar,23Richards J.R. Ormsby E.L. Romo M.V. Gillen M.A. McGahan J.P. Blunt abdominal injury in the pregnant patient: detection with US.Radiology. 2004; 233: 463-470Crossref PubMed Scopus (52) Google Scholar For example, there is a high false-negative rate for ultrasound detection of stone disease in the nonpregnant population, whereas there is a high false positive rate in pregnant women owing to the underlying physiologic changes in the urinary system.21Patel S.J. Reede D.L. Katz D.S. Subramaniam R. Amorosa J.K. 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The role of imaging in the diagnosis and management of renal stone disease in pregnancy.Clin Radiol. 2015; 70: 1462-1471Abstract Full Text Full Text PDF Scopus (16) Google Scholar Measurement of the resistive index (RI) within the kidneys using Doppler ultrasound may be useful to distinguish between benign pregnancy-related hydronephrosis and pathologic causes of urinary tract dilation.21Patel S.J. Reede D.L. Katz D.S. Subramaniam R. Amorosa J.K. Imaging the pregnant patient for nonobstetric conditions: algorithms and radiation dose considerations.Radiographics. 2007; 27: 1705-1722Crossref PubMed Scopus (293) Google Scholar RI elevations >0.70 are suggestive of underlying kidney dysfunction in pregnant patients,25Hertzberg B.S. Carroll B.A. Bowie J.D. et al.Doppler US assessment of maternal kidneys: analysis of intrarenal resistivity indexes in normal pregnancy and physiologic pelvicaliectasis.Radiology. 1993; 186: 689-692Crossref PubMed Scopus (64) Google Scholar and an RI difference of ≥0.04 between normal and abnormal kidneys is consistent with pathologic urinary tract obstruction.26Shokeir A.A. Mahran M.R. Abdulmaaboud M. Renal colic in pregnant women: role of renal resistive index.Urology. 2000; 55: 344-347Abstract Full Text Full Text PDF PubMed Scopus (111) Google Scholar There are no reported cases of fetal injury related to Doppler ultrasound, and it is considered safe to use during pregnancy,27Committee on Obstetric PracticeCommittee Opinion No. 723: guidelines for diagnostic imaging during pregnancy and lactation.Obstet Gynecol. 2017; 130: e210-e216Crossref PubMed Scopus (277) Google Scholar but Doppler evaluation carries a theoretical risk of thermal and acoustic damage and some experts recommend keeping its use to a minimum to avoid possible harm.16Masselli G. Derme M. Bernieri M.G. et al.Stone disease in pregnancy: imaging-guided therapy.Insights Imaging. 2014; 5: 691-696Crossref Scopus (17) Google Scholar Overall, ultrasound is a relatively inexpensive and safe modality of diagnostic kidney imaging in pregnant patients. Limitations from low sensitivity may be counterbalanced by high specificity23Richards J.R. Ormsby E.L. Romo M.V. Gillen M.A. McGahan J.P. Blunt abdominal injury in the pregnant patient: detection with US.Radiology. 2004; 233: 463-470Crossref PubMed Scopus (52) Google Scholar if able to detect underlying anatomic kidney abnormalities and potentially avoid more costly, invasive, or risky procedures during pregnancy. Other pathological structural findings (eg, cystic kidney disease) identified during pregnancy may require further evaluation if imaging is likely to provide a change in management, but the decision to pursue additional imaging studies should be performed cautiously with the goal of minimizing the potential for fetal risk (Fig 1). Magnetic resonance imaging (MRI) is considered second line for imaging pregnant patients if ultrasound is nondiagnostic (approximately 40%),12Masselli G. Weston M. Spencer J. The role of imaging in the diagnosis and management of renal stone disease in pregnancy.Clin Radiol. 2015; 70: 1462-1471Abstract Full Text Full Text PDF Scopus (16) Google Scholar patients fail to respond to conservative therapies, and the benefits of further imaging studies outweigh the potential risks.12Masselli G. Weston M. Spencer J. The role of imaging in the diagnosis and management of renal stone disease in pregnancy.Clin Radiol. 2015; 70: 1462-1471Abstract Full Text Full Text PDF Scopus (16) Google Scholar,18Jaffe T.A. Miller C.M. Merkle E.M. Practice patterns in imaging of the pregnant patient with abdominal pain: a survey of academic centers.AJR Am J Roentgenol. 2007; 189: 1128-1134Crossref PubMed Scopus (54) Google Scholar Similar to ultrasound, MRI does not subject the patient or fetus to ionizing radiation and its associated risks, and MRI is considered a safe modality to use for imaging the kidney and urinary tract during pregnancy.27Committee on Obstetric PracticeCommittee Opinion No. 723: guidelines for diagnostic imaging during pregnancy and lactation.Obstet Gynecol. 2017; 130: e210-e216Crossref PubMed Scopus (277) Google Scholar Its primary advantage is that it provides high-quality images of soft tissues, including the kidneys and urinary tract, and may offer clarity in the event of nondiagnostic ultrasound in pregnant patients. However, MRI sensitivity for diagnosing structural kidney disease may be affected by patient factors (ie, ability to follow breath-holding instructions and remain motionless for the duration of the examination).28Nikken J.J. Krestin G.P. MRI of the kidney-state of the art.Eur Radiol. 2007; 17: 2780-2793Crossref PubMed Scopus (112) Google Scholar MRI is more costly and less portable than ultrasound and is poorly able to detect small urinary calculi12Masselli G. Weston M. Spencer J. The role of imaging in the diagnosis and management of renal stone disease in pregnancy.Clin Radiol. 2015; 70: 1462-1471Abstract Full Text Full Text PDF Scopus (16) Google Scholar,21Patel S.J. Reede D.L. Katz D.S. Subramaniam R. Amorosa J.K. Imaging the pregnant patient for nonobstetric conditions: algorithms and radiation dose considerations.Radiographics. 2007; 27: 1705-1722Crossref PubMed Scopus (293) Google Scholar but has comparatively high sensitivity and specificity than ultrasound in diagnosing pathologic obstruction of the urinary tract.29Roy C. Saussine C. LeBras Y. et al.Assessment of painful ureterohydronephrosis during pregnancy by MR urography.Eur Radiol. 1996; 6: 334-338Crossref PubMed Scopus (79) Google Scholar As with Doppler ultrasound, concerns have been raised regarding thermal and acoustic injury to the fetus from MRI, but this risk remains theoretical.19Wieseler K.M. Bhargava P. Kanal K.M. Vaidya S. Stewart B.K. Dighe M.K. Imaging in pregnant patients: examination appropriateness.Radiographics. 2010; 30 (discussion 30-33): 1215-1229Crossref PubMed Scopus (113) Google Scholar To date, there is no evidence of increased teratogenicity or thermal injury associated with MRI performed during pregnancy.12Masselli G. Weston M. Spencer J. The role of imaging in the diagnosis and management of renal stone disease in pregnancy.Clin Radiol. 2015; 70: 1462-1471Abstract Full Text Full Text PDF Scopus (16) Google Scholar Computed tomography (CT) scans are generally avoided in pregnant patients whenever possible to minimize fetal exposure to ionizing radiation, particularly during the first trimester when there is active organogenesis, and the risks for fetal loss, malformations, and intellectual deficits as a result of exposure to radiation are highest.27Committee on Obstetric PracticeCommittee Opinion No. 723: guidelines for diagnostic imaging during pregnancy and lactation.Obstet Gynecol. 2017; 130: e210-e216Crossref PubMed Scopus (277) Google Scholar Imaging modalities that use ionizing radiation may be justified in pregnant women if medically necessary to preserve the life and health of the mother and no other imaging alternatives are available or likely to be diagnostically adequate.12Masselli G. Weston M. Spencer J. The role of imaging in the diagnosis and management of renal stone disease in pregnancy.Clin Radiol. 2015; 70: 1462-1471Abstract Full Text Full Text PDF Scopus (16) Google Scholar The risk of fetal damage from ionizing radiation varies depending on gestational age and frequency of exposure.21Patel S.J. Reede D.L. Katz D.S. Subramaniam R. Amorosa J.K. Imaging the pregnant patient for nonobstetric conditions: algorithms and radiation dose considerations.Radiographics. 2007; 27: 1705-1722Crossref PubMed Scopus (293) Google Scholar,27Committee on Obstetric PracticeCommittee Opinion No. 723: guidelines for diagnostic imaging during pregnancy and lactation.Obstet Gynecol. 2017; 130: e210-e216Crossref PubMed Scopus (277) Google Scholar,30American College of RadiologyACR-SPR Practice Parameter for Imaging Pregnant or Potentially Pregnant Adolescents and Women with Ionizing Radiation. ACR, Reston (VA)2018Google Scholar Both the American College of Obstetrics and Gynecology and the American College of Radiology recommend that, if necessary, low-dose CT scans be performed in pregnant patients, such that radiation dose is "as low as reasonably achievable" to provide quality images but minimize the potential for fetal harm.19Wieseler K.M. Bhargava P. Kanal K.M. Vaidya S. Stewart B.K. Dighe M.K. Imaging in pregnant patients: examination appropriateness.Radiographics. 2010; 30 (discussion 30-33): 1215-1229Crossref PubMed Scopus (113) Google Scholar,27Committee on Obstetric PracticeCommittee Opinion No. 723: guidelines for diagnostic imaging during pregnancy and lactation.Obstet Gynecol. 2017; 130: e210-e216Crossref PubMed Scopus (277) Google Scholar,30American College of RadiologyACR-SPR Practice Parameter for Imaging Pregnant or Potentially Pregnant Adolescents and Women with Ionizing Radiation. ACR, Reston (VA)2018Google Scholar The cumulative dose of ionizing radiation to the fetus should not exceed the threshold of 50 mGy (5 rad) throughout the gestational period.27Committee on Obstetric PracticeCommittee Opinion No. 723: guidelines for diagnostic imaging during pregnancy and lactation.Obstet Gynecol. 2017; 130: e210-e216Crossref PubMed Scopus (277) Google Scholar Nonemergent imaging of the kidneys and urinary tract using CT during pregnancy is not frequently performed in many centers across the United States owing to concerns for the potential risks being disproportionate to the benefits.18Jaffe T.A. Miller C.M. Merkle E.M. Practice patterns in imaging of the pregnant patient with abdominal pain: a survey of academic centers.AJR Am J Roentgenol. 2007; 189: 1128-1134Crossref PubMed Scopus (54) Google Scholar Nevertheless, some centers report using nonenhanced, low-dose CT to aid in diagnosis when there is a high suspicion of lower urinary tract stone disease in a pregnant patient.18Jaffe T.A. Miller C.M. Merkle E.M. Practice patterns in imaging of the pregnant patient with abdominal pain: a survey of academic centers.AJR Am J Roentgenol. 2007; 189: 1128-1134Crossref PubMed Scopus (54) Google Scholar,19Wieseler K.M. Bhargava P. Kanal K.M. Vaidya S. Stewart B.K. Dighe M.K. Imaging in pregnant patients: examination appropriateness.Radiographics. 2010; 30 (discussion 30-33): 1215-1229Crossref PubMed Scopus (113) Google Scholar In nonemergent situations where imaging modalities that use ionizing radiation are being considered, however, consultation with a medical physicist, who may provide precise estimates of total fetal radiation dose, is encouraged (Fig 1).19Wieseler K.M. Bhargava P. Kanal K.M. Vaidya S. Stewart B.K. Dighe M.K. Imaging in pregnant patients: examination appropriateness.Radiographics. 2010; 30 (discussion 30-33): 1215-1229Crossref PubMed Scopus (113) Google Scholar Microbubble contrast is sometimes used to enhance ultrasound evaluation of the kidneys and their associated vasculature. There are no known fetal risks associated with the use of ultrasound contrast agents, but at present, there are few studies evaluating their safety in pregnant women.31Puac P. Rodriguez A. Vallejo C. Zamora C.A. Castillo M. Safety of contrast material use during pregnancy and lactation.Magn Reson Imaging Clin N Am. 2017; 25: 787-797Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar Gadolinium used for MRI is administered in a chelated form and may cross the placenta.32Tirada N. Dreizin D. Khati N.J. Akin E.A. Zeman R.K. Imaging pregnant and lactating patients.Radiographics. 2015; 35: 1751-1765Crossref PubMed Scopus (118) Google Scholar The free form of gadolinium is neurotoxic, and human studies of its safety have been limited. However, animal studies demonstrate potential toxicity to the fetus from the use of gadolinium agents during pregnancy.31Puac P. Rodriguez A. Vallejo C. Zamora C.A. Castillo M. Safety of contrast material use during pregnancy and lactation.Magn Reson Imaging Clin N Am. 2017; 25: 787-797Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar,33Tremblay E. Therasse E. Thomassin-Naggara I. Trop I. Quality initiatives: guidelines for use of medical imaging during pregnancy and lactation.Radiographics. 2012; 32: 897-911Crossref PubMed Scopus (181) Google Scholar For this reason, gadolinium contrast for MRI performed in pregnant women should be only used in cases where absolutely necessary to obtain quality images and no other imaging alternative is possible.27Committee on Obstetric PracticeCommittee Opinion No. 723: guidelines for diagnostic imaging during pregnancy and lactation.Obstet Gynecol. 2017; 130: e210-e216Crossref PubMed Scopus (277) Google Scholar,33Tremblay E. Therasse E. Thomassin-Naggara I. Trop I. Quality initiatives: guidelines for use of medical imaging during pregnancy and lactation.Radiographics. 2012; 32: 897-911Crossref PubMed Scopus (181) Google Scholar Using iodinated contrast during pregnancy has raised concerns regarding its effect on fetal thyroid development.21Patel S.J. Reede D.L. Katz D.S. Subramaniam R. Amorosa J.K. Imaging the pregnant patient for nonobstetric conditions: algorithms and radiation dose considerations.Radiographics. 2007; 27: 1705-1722Crossref PubMed Scopus (293) Google Scholar At present, the potential risk thyroid dysfunction in the fetus as a result of exposure to iodinated contrast has not been supported by clinical evidence.19Wieseler K.M. Bhargava P. Kanal K.M. Vaidya S. Stewart B.K. Dighe M.K. Imaging in pregnant patients: examination appropriateness.Radiographics. 2010; 30 (discussion 30-33): 1215-1229Crossref PubMed Scopus (113) Google Scholar,21Patel S.J. Reede D.L. Katz D.S. Subramaniam R. Amorosa J.K. Imaging the pregnant patient for nonobstetric conditions: algorithms and radiation dose considerations.Radiographics. 2007; 27: 1705-1722Crossref PubMed Scopus (293) Google Scholar,31Puac P. Rodriguez A. Vallejo C. Zamora C.A. Castillo M. Safety of contrast material use during pregnancy and lactation.Magn Reson Imaging Clin N Am. 2017; 25: 787-797Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar,34Bourjeily G. Chalhoub M. Phornphutkul C. Alleyne T.C. Woodfield C.A. Chen K.K. Neonatal thyroid function: effect of a single exposure to iodinated contrast medium in utero.Radiology. 2010; 256: 744-750Crossref PubMed Scopus (103) Google Scholar Iodinated contrast is thus considered safe for use in pregnancy. However, in cases of fetal exposure to iodinated contrast in utero, neonatal thyroid screen within the first week of life is recommended.21Patel S.J. Reede D.L. Katz D.S. Subramaniam R. Amorosa J.K. Imaging the pregnant patient for nonobstetric conditions: algorithms and radiation dose considerations.Radiographics. 2007; 27: 1705-1722Crossref PubMed Scopus (293) Google Scholar,27Committee on Obstetric PracticeCommittee Opinion No. 723: guidelines for diagnostic imaging during pregnancy and lactation.Obstet Gynecol. 2017; 130: e210-e216Crossref PubMed Scopus (277) Google Scholar Kidney biopsy during pregnancy poses several unique challenges. Typical prone positioning for biopsy is frequently not possible during later stages of pregnancy, and alternate positioning (ie, lateral decubitus or seated) may cause the procedure to become more technically difficult.35Hladunewich M.A. Bramham K. Jim B. Maynard S. Managing glomerular disease in pregnancy.Nephrol Dial Transpl. 2017; 32: i48-i56Crossref PubMed Scopus (10) Google Scholar Pregnant women being considered for kidney biopsy may be at generally higher risk of maternal or fetal complications from biopsy related to their underlying comorbidities.36Piccoli G.B. Cabiddu G. Attini R. et al.Risk of adverse pregnancy outcomes in women with CKD.J Am Soc Nephrol. 2015; 26: 2011-2022Crossref PubMed Scopus (213) Google Scholar Both the mother and fetus are affected if serious complications (eg, hemorrhage) occur. On the other hand, biopsy may provide a definitive diagnosis and lead to a change in clinical management.37Day C. Hewins P. Hildebrand S. et al.The role of renal biopsy in women with kidney disease identified in pregnancy.Nephrol Dial Transpl. 2008; 23: 201-206Crossref PubMed Scopus (48) Google Scholar Therefore, the benefits of kidney biopsy for clinical diagnosis and management during pregnancy must be carefully weighed against the potential risks for harm (Table 1).Table 1Potential Complications of Kidney Biopsy in Pregnant PatientsMinor ComplicationsMajor Complications•Microscopic hematuria•Macroscopic hematuria•Minor postprocedural loin pain•Small perirenal hematoma without need for blood transfusion•Hemodynamic instability leading to escalation of care (ie, intensive care unit hospitalization)•Hematoma/hemorrhage necessitating blood transfusion(s)•Preterm labor and delivery•Fetal loss•Maternal death Open table in a new tab Studies evaluating the safety of kidney biopsy in pregnancy have largely come from single centers and are limited by small numbers, observational design, and varying indications for kidney biopsy and definitions of severe postbiopsy complications.38Piccoli G.B. Daidola G. Attini R. et al.Kidney biopsy in pregnancy: evidence for counselling? A systematic narrative review.BJOG. 2013; 120: 412-427Crossref PubMed Scopus (81) Google Scholar A study by Chen and colleagues39Chen H.H. Lin H.C. Yeh J.C. Chen C.P. Renal biopsy in pregnancies complicated by undetermined renal disease.Acta Obstet Gynecol Scand. 2001; 80: 888-893Crossref PubMed Google Scholar reported 15 primigravida women 3.5 g/1.73 m2/day, between 1990 an 1999. Kidney biopsy was diagnostic in all of the study patients. Eight had lupus nephritis, 3 had chronic glomerulonephritis, 2 had mesangial proliferative glomerulonephritis, 1 had diabetic glomerulosclerosis, and 1 had endocapillary proliferative glomerulonephritis. One patient developed gross hematuria after biopsy but did not require blood transfusion or hemodynamic support. No patients died as a direct result of the kidney biopsy. The study concluded that kidney biopsy is not contraindicated during pregnancy and is useful for clinical counseling or therapeutic management. Another more recent single-center study reported similar kidney biopsy complication rates among pregnant women to be mild and comparable with those in nonpregnant women,37Day C. Hewins P. Hildebrand S. et al.The role of renal biopsy in women with kidney disease identified in pregnancy.Nephrol Dial Transpl. 2008; 23: 201-206Crossref PubMed Scopus (48) Google Scholar whereas another center found kidney biopsy in the perinatal period to be a "morbid procedure" resulting in 7 of the 18 study patients (15 antepartum and 3 postpartum) to develop postprocedure perinephric hematomas, 2 of whom required blood transfusion (1 antepartum and 1 postpartum).40Kuller J.A. D'Andrea N.M. McMahon M.J. Renal biopsy and pregnancy.Am J Obstet Gynecol. 2001; 184: 1093-1096Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar In a study from the United Kingdom, Day and colleagues37Day C. Hewins P. Hildebrand S. et al.The role of renal biopsy in women with kidney disease identified in pregnancy.Nephrol Dial Transpl. 2008; 23: 201-206Crossref PubMed Scopus (48) Google Scholar reported on kidney biopsy in 20 women who underwent antepartum kidney biopsy and 75 with kidney disease diagnosed during pregnancy but underwent postpartum biopsy from 1983 to 2004. Median gestational age at biopsy was 20.5 weeks (range 6-31 weeks). Patients were followed up for a median of 103.3 months (range 2.5-256 months). Sixty-four percent of the patients in the antepartum biopsy cohort had a glomerular disorder, most commonly either lupus nephritis or focal segmental glomerulosclerosis. Nine of the 20 patients (40%) had subsequent initiation or escalation of medical therapy (eg, immunosuppressant medications) as a direct result of the biopsy. Only 1 patient had minor hematuria after biopsy that was managed with observation. Pregnant patients with greater severity of kidney disease (as determined by Modification of Diet in Renal Disease equation estimate of GFR) at the time of kidney biopsy were more likely to have obstetrical complications such as preeclampsia, preterm delivery, or delivery via caesarean section. A systematic review by Piccoli and colleagues38Piccoli G.B. Daidola G. Attini R. et al.Kidney biopsy in pregnancy: evidence for counselling? A systematic narrative review.BJOG. 2013; 120: 412-427Crossref PubMed Scopus (81) Google Scholar evaluated 39 studies encompassing 243 antepartum and 1236 postpartum kidney biopsies within 2 months of delivery from 1966–1981 to 2007–2008 and found no clear trend of reduced risk of kidney biopsy–related complications in pregnant women over time despite the incorporation of ultrasound guidance into routine clinical practice. Within these studies, the reported complications varied based on the timing of the biopsy (antepartum or postpartum), with a 2% (4 of 197) severe complication rate due to bleeding in patients who were biopsied during pregnancy, in comparison with a prior series from 1987 analyzing outcomes of 111 kidney biopsies in 104 pregnant women, which showed a 4.5% complication rate in women aged 20 years and older who underwent kidney biopsy in pregnancy.41Packham D. Fairley K.F. Renal biopsy: indications and complications in pregnancy.Br J Obstet Gynaecol. 1987; 94: 935-939Crossref PubMed Scopus (68) Google Scholar Overall, the recent Piccoli and colleagues38Piccoli G.B. Daidola G. Attini R. et al.Kidney biopsy in pregnancy: evidence for counselling? A systematic narrative review.BJOG. 2013; 120: 412-427Crossref PubMed Scopus (81) Google Scholar study found that there was an increased risk of all (major and minor) biopsy-related complications in those undergoing antepartum (7%) vs postpartum biopsy (1%), P = 0.001. Because of the potential risk to the mother and fetus should complications occur, kidney biopsy should not be performed simply to confirm a clinical diagnosis of preeclampsia.35Hladunewich M.A. Bramham K. Jim B. Maynard S. Managing glomerular disease in pregnancy.Nephrol Dial Transpl. 2017; 32: i48-i56Crossref PubMed Scopus (10) Google Scholar However, biopsy may be indicated in pregnant patients with a sudden, severe decrease in GFR or new development of nephrotic-range proteinuria, and in whom less-invasive means of diagnosis have failed to elucidate disease etiology.35Hladunewich M.A. Bramham K. Jim B. Maynard S. Managing glomerular disease in pregnancy.Nephrol Dial Transpl. 2017; 32: i48-i56Crossref PubMed Scopus (10) Google Scholar In particular, kidney biopsy may play a key role in the diagnosis of de novo lupus nephritis or acute lupus flare in those previously diagnosed with lupus nephritis. Clinical suspicion is not sufficient to diagnose lupus nephritis, even if supported by laboratory evaluation, because underlying histopathology is crucial to guiding treatment.42Grande J.P. Balow J.E. Renal biopsy in lupus nephritis.Lupus. 1998; 7: 611-617Crossref PubMed Scopus (68) Google Scholar,43Haladyj E. Cervera R. Do we still need renal biopsy in lupus nephritis?.Reumatologia. 2016; 54: 61-66Crossref Scopus (18) Google Scholar A study from Chen and colleagues44Chen T.K. Gelber A.C. Witter F.R. Petri M. Fine D.M. Renal biopsy in the management of lupus nephritis during pregnancy.Lupus. 2015; 24: 147-154Crossref PubMed Scopus (21) Google Scholar examined the results of kidney biopsy in 11 women with systemic lupus erythematosus at Johns Hopkins University over an 11-year period from 2001 to 2012. The decision to perform kidney biopsy was based on the clinical judgment of the attending rheumatologist and nephrologist. Patients were biopsied in prone position at a median of 16 weeks of gestation (range 9-27 weeks) using ultrasound guidance. To be eligible for kidney biopsy, all patients had to have a blood pressure of ≤160/100 mm Hg, platelet count ≥50,000, partial thromboplastin time <42.1 seconds, and international normalized ratio of <1.3. All women included in the study had at least 500 mg/24 hours proteinuria; 73% had positive anti-double stranded DNA titer and 82% had low complement levels. In 10 of 11 patients (91%), clinical management of disease was altered based on biopsy results. The study concluded that the benefits of kidney biopsy in pregnant patients with lupus nephritis outweigh the risks, especially given that untreated disease may result in maternal severe long-term organ damage and is associated with poor pregnancy outcomes.45Tedeschi S.K. Guan H. Fine A. Costenbader K.H. Bermas B. Organ-specific systemic lupus erythematosus activity during pregnancy is associated with adverse pregnancy outcomes.Clin Rheumatol. 2016; 35: 1725-1732Crossref Scopus (25) Google Scholar Nevertheless, determining the appropriateness of kidney biopsy during pregnancy depends on clinical judgment, the individual patient's clinical status, gestational age, the probability of harm from the procedure relative to the potential benefit of having a definitive diagnosis, and whether biopsy is likely to result in a significant change in clinical management (Table 2).Table 2Determining the Appropriateness of Kidney Biopsy in Pregnant Patients35Hladunewich M.A. Bramham K. Jim B. Maynard S. Managing glomerular disease in pregnancy.Nephrol Dial Transpl. 2017; 32: i48-i56Crossref PubMed Scopus (10) Google Scholar,37Day C. Hewins P. Hildebrand S. et al.The role of renal biopsy in women with kidney disease identified in pregnancy.Nephrol Dial Transpl. 2008; 23: 201-206Crossref PubMed Scopus (48) Google ScholarConsider Biopsy if•Biopsy is likely to change clinical management or enable progression of pregnancy to fetal viability•Unable to diagnose through less-invasive measures•Accurate diagnosis is necessary to preserve the life of the mother• 10 cm in size•Preeclampsia and physiologic rise in urine protein has been excluded•Active urinary sediment•Blood pressure is well controlled (ie, <160/100 mm Hg and preferably 160/100 mm Hg)•Uncorrected coagulopathy•Patient has responded to empiric therapyAbbreviation: GFR, glomerular filtration rate.∗ Asymptomatic bacteriuria should be treated with appropriate antibiotics for 3–7 days before kidney biopsy. If the biopsy cannot be delayed and asymptomatic bacteriuria is present, it is reasonable to initiate antibiotics prior to the procedure and continue treatment for a total of 3–7 days. Open table in a new tab Abbreviation: GFR, glomerular filtration rate. Women with acute worsening of kidney function or significant proteinuria during pregnancy may require further workup with imaging studies or kidney biopsy to provide accurate diagnosis and permit targeted clinical therapy. Ultrasound should be prioritized if kidney imaging is essential to diagnosis during pregnancy. In cases where ultrasound is nondiagnostic, other imaging modalities may be considered. MRI without gadolinium contrast is preferable to CT in pregnant patients. Kidney imaging modalities that require ionizing radiation should generally be avoided for routine use in pregnant patients. The decision to perform kidney biopsy in a pregnant patient should always be made with careful consideration of the risks and the benefits to both the mother and the fetus. Severe bleeding complications are relatively rare, but the risk of any complication associated with kidney biopsy is increased in the antepartum period compared with the immediate postpartum period. In patients with sudden, severe decrease in GFR, nephrotic-range proteinuria, or known or suspected lupus nephritis, however, biopsy may be the best means to determine type and extent of disease and to direct clinical therapy. Diagnosing kidney disease in pregnant patients should begin with the least invasive means of diagnosis, with more invasive or potentially risky tests or procedures being reserved for cases where absolutely necessary and where they are likely to improve clinical outcomes.
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