No Greater Risk for Aneurysm Rupture in Pregnancy, Delivery

Pauline Anderson

Feb 26, 2013

 

A new study has found no increased risk for aneurysm rupture during pregnancy and delivery, suggesting that the relatively high rate of cesarean deliveries among women with an unruptured aneurysm that was also uncovered by the study may be unnecessary.

Further, the researchers found that when an aneurysm does rupture, prompt obliteration using surgical clipping or endovascular coiling may decrease poor outcomes.

"No one knows what the risk of rupture of a cerebral aneurysm is in a pregnant woman, or what the risk is with vaginal delivery," said study senior author, Brian Hoh, MD, the William Merz Associate Professor of Neurosurgery at the University of Florida, Gainesville. "We attempted to answer these questions using a large national hospital database."

The study appeared in the February issue of the journalNeurosurgery.

Clipping, Coiling

The researchers gathered hospital discharge data involving pregnancies or deliveries from the Nationwide Inpatient Sample (NIS) for 1988 to 2009. During that time, 2,715,161 hospitalizations were related to pregnancies; of these, 193 involved unruptured aneurysms and 714, ruptured aneurysms.

The investigators estimated the prevalence of unruptured aneurysms in the general population of women to be 3.95%, about half of that previously reported in the general population, and further estimated the rate to be 1.8% among women of child-bearing age, 45.3% as high as that among all women.

Assuming that rate of 1.8%, the researchers estimated that 48,873 of the hospitalized women had unruptured aneurysms. The estimated risk for aneurysm rupture during pregnancy was therefore 1.4% (714 of 48,873; 95% confidence interval [CI], 1.35% - 1.57%).

There were 17,340,466 hospitalizations involving deliveries, of which 218 involved unruptured and 172 ruptured aneurysms. Again, assuming a rate of 1.8%, 312,128 of these women had undetected unruptured aneurysms. This led to an estimated risk for an aneurysm rupture during delivery of 0.05% (172 of 312,128; 95% CI, 0.0468% - 0.0634%).

The study showed that the probability of a woman with an aneurysm during pregnancy receiving clipping is significantly higher than that of her receiving coiling. Of the 714 hospitalized pregnant women with a ruptured aneurysm, 2.9% received coiling, 10.5% received clipping, and 86.6% received neither. Of the 172 hospitalizations involving ruptured aneurysms with delivery, 4.7% received coiling, 12.8% received clipping, and 82.5% received neither.

The authors noted that for pregnancy, the mortality rate among patients who received no treatment was almost double that among those who received clipping or coiling (10.2% vs 5.2%).

Cesarean Deliveries

The researchers estimated a national cesarean delivery rate of 25.52% (95% CI, 25.50% - 25.54%). But among patients with unruptured aneurysm, the estimated rate was 70.18% (95% CI, 64.06% - 76.30%; P< .001).

The authors noted that there are no evidence-based recommendations for obstetric management in patients with unruptured intracranial aneurysm and no evidence to suggest that maternal or fetal outcome is improved by cesarean delivery compared with closely supervised vaginal delivery.

"Because the finding of an unruptured cerebral aneurysm in a pregnant woman is so rare, there is little evidence to guide obstetricians and neurosurgeons in the care of these patients," said Dr. Hoh.

The method of delivery for women with intracranial unruptured aneurysm should be based on obstetric considerations, he said. "Cesarean delivery would be indicated in several circumstances, such as when the clinical state of the mother is severe," for example, coma or brainstem damage, or when the aneurysm is diagnosed at labor.

The study was relatively small, which diminished its statistical power and limited the ability to incorporate covariates into the analysis, the authors note. Another limitation was that the diagnostic codes that were used may be incomplete.

Numbers Questioned

In an accompanying comment, R. Loch Macdonald, professor, surgery/neurosurgery, University of Toronto, division head, neurosurgery, St. Michael's Hospital, Toronto, Ontario, Canada, noted that the NIS is not population-based database because it includes selected patients admitted to a subset of hospitals, and that only 13% to 20% of the patients in the study who were coded as having subarachnoid hemorrhage were treated.

"There is something wrong with this number," he writes, adding that the figure is markedly lower than the percentage treated at hospitals such as his institution, St. Michael's, where the only cases not treated are those with nonaneurysmal subarachnoid hemorrhage and patients in very poor condition who are not expected to survive.

He also questioned the authors' estimates of pregnant women with unruptured and ruptured aneurysms. Patients with these aneurysms do tend to be female, but they're older and cigarette smokers, he said.

"The authors try to adjust for this and derive a 1.8% incidence of unruptured aneurysms among women 16 to 44 years of age," but this could still be an overestimation.

"Overall, this report adds to the literature, suggesting that, although intracranial hemorrhage is an important cause of obstetrical morbidity and mortality, aneurysmal cases are rare, and, if they are more likely to occur during pregnancy and the puerperium, then this increased risk is likely to be small."

The authors have disclosed no relevant financial relationships.

Neurosurgery. 2013;72:143-150. Abstract