Hypertensive disorders of pregnancy and the recent increase in obstetric acute renal failure in Canada: population based retrospective cohort studyBMJ 2014; 349 doi: https://doi.org/10.1136/bmj.g4731 (Published 30 July 2014) Cite this as: BMJ 2014;349:g4731
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The Western world is experiencing well-documented epidemics of many reproductive disorders including preterm labour (PTL), preeclampsia (PET), and, postpartum haemorrhage (PPH) (1). Some of these conditions result from injuries to uterine nerves caused by straining during defaecation, surgical evacuation of the uterus, and, “difficult” (induced) first labours (2). All these antecedents of injuries to pelvic nerves are increasing in frequency in Western populations.
Impaired uterine contractility (PPH), increased sensitivity to opportunist infection (PTL), and, activation of uterorenal autonomic nerves by stretching injured uterine nerves (PET), are plausible mechanisms for the respective conditions with varying degrees of evidence for these effects. (2). In preeclampsia, injured uterine nerves may express (purinergic) mechanoreceptors that are sensitive to “stretch”, activating uterorenal nerves that cause renal cortical vasoconstriction, hypertension and proteinuria which, if sustained, may result in acute renal failure (3).
Many factors may contribute to the increase in acute renal failure observed in this Canadian study (4) including the increased incidence of preeclampsia and its antecedents, but also subtle and mundane changes such as the widespread use of automated blood pressure measurement devices that consistently under-record maternal blood pressure leading to prolonged maternal exposures to sustained hypertension (5). Disentangling the precise causes of the recent increase in acute renal failure may be difficult though reducing rates of injury to pelvic nerves may protect women and their children from many of these fearsome, obstetric complications.
(1) Kramer MS, Berg C, Abenhaim H, Dahhou M, Rouleau J, Mehrabadi A, Joseph KS.
Incidence, risk factors, and temporal trends in severe postpartum haemorrhage.
Am J Obstet Gynecol 2013; 209:449.e1-7.
(2) Quinn MJ.
Autonomic denervation and Western diseases.
Am J Med 2014 (Jan); 127(1):3-4.
(3) Quinn MJ.
Preeclampsia: two placental phenotypes, one etiology ?
Am J Obstet Gynecol. 2014 Apr 30. pii: S0002-9378(14)00389-5.
(4) Mehrabadi A, Liu S, Bartholomew S, Hutcheon JA, Magee LA, Kramer MS, Liston RM, Joseph KS; Canadian Perinatal Surveillance System (Public Health Agency of Canada).
Hypertensive disorders of pregnancy and the recent increase in obstetric
acute renal failure in Canada: population based retrospective cohort study.
BMJ. 2014 Jul 30;349:g4731. doi: 10.1136/bmj.g4731.
(5) Quinn M.
Automated blood pressure measurement devices: a potential source of
morbidity in preeclampsia? Am J Obstet Gynecol. 1994; 170(5 Pt 1):1303-7.
Competing interests: No competing interests
Re: Hypertensive disorders of pregnancy and the recent increase in obstetric acute renal failure in Canada: population based retrospective cohort study
I read with interest the study by Mehrabadi and colleagues (authors), but have reservations about their study methodology.1 The authors observed that the rates of obstetric acute renal failure rose from 1.66 to 2.68 per 10,000 deliveries, when deliveries that occurred during 2003-04 were compared to those from 2009-10.1 This temporal increase was particularly related to gestational (pregnancy related) hypertension with significant proteinuria (preeclampsia); but the prevalence of preeclampsia remained stable (1.1%) during the study period.1 Women diagnosed with a severe form of preeclampsia (uncontrolled blood pressure despite appropriate doses of anti hypertensive) are usually offered delivery with the view to minimise maternal morbidity and case fatality. The authors’ observations about temporal increase in obstetric acute renal failure may be related to increase in the proportion of women diagnosed with this severe form of preeclampsia before delivery was considered.
HELLP (Haemolysis, Elevated Liver enzymes, and Low Platelets) syndrome is a recognised risk factor for acute renal failure in women diagnosed with preeclampsia.2 The authors, however, did not report whether the prevalence of HELLP syndrome was different between the study periods (2003-4 versus 2009-10). I am of the opinion that further studies are needed in this area before firm conclusions are drawn.
1.Mehrabadi A, Liu S, Bartholomew S, Hutcheon JA, Magee MA, Kramer MS et al. Hypertensive disorders of pregnancy and the recent increase in obstetric acute renal failure in Canada: population based retrospective cohort study. BMJ 2014; 349:g4731.
2.Drakeley AJ, Le Roux PA, Anthony J, Penny J. Acute renal failure complicating severe preeclampsia requiring admission to an obstetric intensive care unit. Am J Obstet Gynecol 2002; 186: 253-6.
Competing interests: No competing interests